Journal of Applied Crystallography
http://journals.iucr.org/j/issues/2014/02/00/isscontsbdy.html
Journal of Applied Crystallography covers a wide range of crystallographic topics from the viewpoints of both techniques and theory. The journal presents articles on the application of crystallographic techniques and on the related apparatus and computer software. For many years, Journal of Applied Crystallography has been the main vehicle for the publication of small-angle scattering articles and powder diffraction techniques. The journal is the primary place where crystallographic computer program information is published.enCopyright (c) 2014 International Union of Crystallography2014-04-01International Union of CrystallographyInternational Union of Crystallographyhttp://journals.iucr.orgurn:issn:1600-5767Journal of Applied Crystallography covers a wide range of crystallographic topics from the viewpoints of both techniques and theory. The journal presents articles on the application of crystallographic techniques and on the related apparatus and computer software. For many years, Journal of Applied Crystallography has been the main vehicle for the publication of small-angle scattering articles and powder diffraction techniques. The journal is the primary place where crystallographic computer program information is published.text/htmlJournal of Applied Crystallography, Volume 47, Part 2, 2014textyearly62002-02-01T00:00+00:002472014-04-01Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallography488urn:issn:1600-5767med@iucr.orgApril 20142014-04-01Journal of Applied Crystallographyhttp://journals.iucr.org/logos/rss10j.gif
http://journals.iucr.org/j/issues/2014/02/00/isscontsbdy.html
Still imageEnergy-dispersive X-ray diffraction mapping on a benchtop X-ray fluorescence system
http://scripts.iucr.org/cgi-bin/paper?he5629
A method for energy-dispersive X-ray diffraction mapping is presented, using a conventional low-power benchtop X-ray fluorescence spectrometer, the Seiko Instruments SEA6000VX. Hyper spectral X-ray maps with a 10 µm step size were collected from polished metal surfaces, sectioned Bi, Pb and steel shot gun pellets. Candidate diffraction lines were identified by eliminating those that matched a characteristic line for an element and those predicted for escape peaks, sum peaks, and Rayleigh and Compton scattered primary X-rays. The maps showed that the crystallites in the Bi pellet were larger than those observed in the Pb and steel pellets. The application of benchtop spectrometers to energy-dispersive X-ray diffraction mapping is discussed, and the capability for lower atomic number and lower-symmetry materials is briefly explored using multi-crystalline Si and polycrystalline sucrose.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Lane, D.W.Nyombi, A.Shackel, J.2014-02-22doi:10.1107/S1600576714000314International Union of CrystallographyA method for energy-dispersive X-ray diffraction mapping is presented, using a conventional low-power benchtop X-ray fluorescence spectrometer. Maps are presented for Bi, Pb and steel shot gun pellets and the capability for lower atomic number and lower-symmetry materials is briefly explored.ENX-ray fluorescenceX-ray diffractionenergy-dispersive X-ray diffractionmappingtextureshot gun pelletsforensic sciencemulti-crystalline siliconA method for energy-dispersive X-ray diffraction mapping is presented, using a conventional low-power benchtop X-ray fluorescence spectrometer, the Seiko Instruments SEA6000VX. Hyper spectral X-ray maps with a 10 µm step size were collected from polished metal surfaces, sectioned Bi, Pb and steel shot gun pellets. Candidate diffraction lines were identified by eliminating those that matched a characteristic line for an element and those predicted for escape peaks, sum peaks, and Rayleigh and Compton scattered primary X-rays. The maps showed that the crystallites in the Bi pellet were larger than those observed in the Pb and steel pellets. The application of benchtop spectrometers to energy-dispersive X-ray diffraction mapping is discussed, and the capability for lower atomic number and lower-symmetry materials is briefly explored using multi-crystalline Si and polycrystalline sucrose.text/htmlEnergy-dispersive X-ray diffraction mapping on a benchtop X-ray fluorescence systemtext2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers488494Sub-micrometre depth-gradient measurements of phase, strain and texture in polycrystalline thin films: a nano-pencil beam diffraction approach
http://scripts.iucr.org/cgi-bin/paper?rw5048
A single-scan approach to evaluating chemical and structural gradients in polycrystalline thin films with a resolution of tens of nanometres is reported. Thinned samples are measured in cross section in a transmission geometry with a high-energy X-ray nano-pencil beam. Powder diffraction methods can be used because of the strongly asymmetric beam shape (i.e. the large number of diffracting grains), allowing the solution of structural phases within the film thickness. For each phase, microstructural gradients such as strain, stress, texture and grain size are deduced from two-dimensional diffraction patterns. Sample preparation (i.e. sample thinning), stress release and technique throughput are evaluated. The resolution, precision and limitations are discussed. The efficiency of this approach is demonstrated on ferritic thin films, where the phase ratio and stress gradient (in each phase) have been successfully quantified with a 150 nm depth resolution.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Vaxelaire, N.Gergaud, P.Vaughan, G.B.M.2014-02-22doi:10.1107/S1600576714000557International Union of CrystallographyA single-scan approach to evaluating chemical and structural gradients in polycrystalline thin films with a resolution of tens of nanometres is reported. Thinned samples are measured in cross section in transmission geometry with a high-energy X-ray nano-pencil beam.ENnano-diffractiongradient measurementsstrainstresspolycrystalline thin filmstextureA single-scan approach to evaluating chemical and structural gradients in polycrystalline thin films with a resolution of tens of nanometres is reported. Thinned samples are measured in cross section in a transmission geometry with a high-energy X-ray nano-pencil beam. Powder diffraction methods can be used because of the strongly asymmetric beam shape (i.e. the large number of diffracting grains), allowing the solution of structural phases within the film thickness. For each phase, microstructural gradients such as strain, stress, texture and grain size are deduced from two-dimensional diffraction patterns. Sample preparation (i.e. sample thinning), stress release and technique throughput are evaluated. The resolution, precision and limitations are discussed. The efficiency of this approach is demonstrated on ferritic thin films, where the phase ratio and stress gradient (in each phase) have been successfully quantified with a 150 nm depth resolution.text/htmlSub-micrometre depth-gradient measurements of phase, strain and texture in polycrystalline thin films: a nano-pencil beam diffraction approachtext2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers495504Mini droplets to super droplets: evolution of self-assembled Au droplets on GaAs(111)B and (110)
http://scripts.iucr.org/cgi-bin/paper?rw5068
In this article, the effect of deposition amount on self-assembled Au droplets fabricated on GaAs(111)B and (110) is presented. The investigation is systematically performed by the variation of the Au deposition amount from 2 to 20 nm while fixing the other growth parameters such as annealing temperature and duration to clearly observe the effect. Under identical growth conditions, the self-assembled Au droplets show significantly different size and density depending on the amount of Au deposition: i.e. the average height varies by 436% from 21.8 to 95.5 nm and the average diameter swings by 827% from 52 to 430 nm, showing that the size increase is dominated by the lateral expansion. Meanwhile the average density varies by over two orders of magnitude from 1.24 × 108 to 4.48 × 1010 cm−2 on GaAs(111)B. With relatively low Au deposition amounts, below 3 nm, round dome-shaped mini Au droplets with high packing density can be fabricated, while super large Au droplets result with higher deposition amounts, above 10 nm, with a density two orders of magnitude lower. It is also found that the surface index has a minor effect on the fabrication of self-assembled Au droplets with the variation of deposition amount. The results are systematically analyzed and discussed in terms of atomic force microscopy and scanning electron microscopy images, line profiles, power spectrums, r.m.s. surface roughness, and size and density plots.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Sui, M.Li, M.-Y.Kim, E.-S.Lee, J.2014-02-22doi:10.1107/S1600576713034316International Union of CrystallographyUnder identical growth conditions, self-assembled Au droplets show significantly different size and density depending on the amount of Au deposition. With relatively low Au deposition amounts, below 3 nm, round dome-shaped mini Au droplets with high packing density can be fabricated, while super large Au droplets result with higher deposition amounts, above 10 nm, with a density two orders of magnitude lower.ENnanowire fabricationself-assemblyAu depositionIn this article, the effect of deposition amount on self-assembled Au droplets fabricated on GaAs(111)B and (110) is presented. The investigation is systematically performed by the variation of the Au deposition amount from 2 to 20 nm while fixing the other growth parameters such as annealing temperature and duration to clearly observe the effect. Under identical growth conditions, the self-assembled Au droplets show significantly different size and density depending on the amount of Au deposition: i.e. the average height varies by 436% from 21.8 to 95.5 nm and the average diameter swings by 827% from 52 to 430 nm, showing that the size increase is dominated by the lateral expansion. Meanwhile the average density varies by over two orders of magnitude from 1.24 × 108 to 4.48 × 1010 cm−2 on GaAs(111)B. With relatively low Au deposition amounts, below 3 nm, round dome-shaped mini Au droplets with high packing density can be fabricated, while super large Au droplets result with higher deposition amounts, above 10 nm, with a density two orders of magnitude lower. It is also found that the surface index has a minor effect on the fabrication of self-assembled Au droplets with the variation of deposition amount. The results are systematically analyzed and discussed in terms of atomic force microscopy and scanning electron microscopy images, line profiles, power spectrums, r.m.s. surface roughness, and size and density plots.text/htmlMini droplets to super droplets: evolution of self-assembled Au droplets on GaAs(111)B and (110)text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers505510Rietveld-based energy-dispersive residual stress evaluation: analysis of complex stress fields σij(z)
http://scripts.iucr.org/cgi-bin/paper?rw5069
A method for the evaluation of strongly inhomogeneous residual stress fields in the near-surface region of polycrystalline materials is introduced, which exploits the full information content contained in energy-dispersive (ED) diffraction patterns. The macro-stress-induced diffraction line shifts ΔEψhkl observed in ED sin2ψ measurements are described by modeling the residual stress state σij(z) in real space, based on Rietveld's data analysis concept. Therefore, the proposed approach differs substantially from currently used methods for residual stress gradient analysis such as the `universal plot' method, which enable access to the Laplace stress profiles σij(τ). With the example of shot-peened samples made of either 100Cr6 steel or Al2O3, it is demonstrated that the simultaneous refinement of all diffraction patterns obtained in a sin2ψ measurement with hundreds of diffraction lines provides very stable solutions for the residual stress depth profiles. Furthermore, it is shown that the proposed evaluation concept even allows for consideration of the residual stress component σ33(z) in the thickness direction, which is difficult to detect by conventional sin2ψ analysis.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Apel, D.Klaus, M.Genzel, M.Genzel, C.2014-02-22doi:10.1107/S1600576713034158International Union of CrystallographyEnergy-dispersive synchrotron diffraction was applied to analyse the near-surface residual stress state in polycrystalline materials. A Rietveld-based formalism is introduced which permits a full triaxial data evaluation and, therefore, even the detection of out-of-plane σ33(z) gradients.ENresidual stress analysistriaxial residual stress statedepth gradientsenergy-dispersive diffractionRietveld refinementA method for the evaluation of strongly inhomogeneous residual stress fields in the near-surface region of polycrystalline materials is introduced, which exploits the full information content contained in energy-dispersive (ED) diffraction patterns. The macro-stress-induced diffraction line shifts ΔEψhkl observed in ED sin2ψ measurements are described by modeling the residual stress state σij(z) in real space, based on Rietveld's data analysis concept. Therefore, the proposed approach differs substantially from currently used methods for residual stress gradient analysis such as the `universal plot' method, which enable access to the Laplace stress profiles σij(τ). With the example of shot-peened samples made of either 100Cr6 steel or Al2O3, it is demonstrated that the simultaneous refinement of all diffraction patterns obtained in a sin2ψ measurement with hundreds of diffraction lines provides very stable solutions for the residual stress depth profiles. Furthermore, it is shown that the proposed evaluation concept even allows for consideration of the residual stress component σ33(z) in the thickness direction, which is difficult to detect by conventional sin2ψ analysis.text/htmlRietveld-based energy-dispersive residual stress evaluation: analysis of complex stress fields σij(z)text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers511526Synthesis, formation mechanism and photoelectric properties of GeS nanosheets and nanowires
http://scripts.iucr.org/cgi-bin/paper?he5634
Single-crystalline GeS nanosheets and nanowires have been selectively synthesized by simply varying the reaction conditions via a convenient wet chemical approach. The formation mechanism of the nanosheets and nanowires has been proposed. The results from time-dependent reactions proved that the GeS nanowires were formed by a rolling-up mechanism. Films made of as-synthesized GeS nanosheets and nanowires were found to have an outstanding photoelectric response, suggesting their potential in solar energy applications. The structure, morphology, composition and optical absorption properties of the as-prepared samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Shi, L.Dai, Y.2014-02-22doi:10.1107/S1600576713034535International Union of CrystallographySingle-crystalline GeS nanosheets and nanowires can be selectively synthesized by changing the reaction conditions. The samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy. The growth mechanism of GeS nanowires is proposed to be via a rolling-up process.ENGeS nanosheetsGeS nanowiresX-ray powder diffractionenergy-dispersive X-ray spectrometrytransmission electron microscopyscanning electron microscopySingle-crystalline GeS nanosheets and nanowires have been selectively synthesized by simply varying the reaction conditions via a convenient wet chemical approach. The formation mechanism of the nanosheets and nanowires has been proposed. The results from time-dependent reactions proved that the GeS nanowires were formed by a rolling-up mechanism. Films made of as-synthesized GeS nanosheets and nanowires were found to have an outstanding photoelectric response, suggesting their potential in solar energy applications. The structure, morphology, composition and optical absorption properties of the as-prepared samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy.text/htmlSynthesis, formation mechanism and photoelectric properties of GeS nanosheets and nanowirestext2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers527531A symmetry-mode description of rigid-body rotations in crystalline solids: a case study of Mg(H2O)6RbBr3
http://scripts.iucr.org/cgi-bin/paper?to5065
The application of rotational symmetry modes to quantitative rigid-body analysis is demonstrated for octahedral rotations in Mg(H2O)6RbBr3. Rigid-body rotations are treated as axial-vector order parameters and projected using group-theoretical methods. The high-temperature crystal structure of the Mg(H2O)6RbBr3 double salt consists of a cubic perovskite-like corner-sharing network of RbBr6 octahedra with isolated MgO6 octahedra at the perovskite A sites. A phase transition occurs at 411 K upon cooling, whereupon the MgO6 octahedra experience a substantial rigid-body rotation, the RbBr6 octahedra are translated but not rotated, and both types of octahedra become slightly distorted. The MgO6 rotation has three orthogonal components associated with the X5−, Γ4+ and X1− irreducible representations of the parent Pm{\overline 3}m space-group symmetry which, given the weakly first-order character of the transition, appear to be strongly coupled. Parametric and sequential refinements of the temperature-dependent structure were conducted using four model types: (1) traditional atomic xyz coordinates for each atom, (2) traditional rigid-body parameters, (3) purely displacive symmetry modes and (4) rigid-body rotational symmetry modes. We demonstrate that rigid-body rotational symmetry modes are an especially effective parameter set for the Rietveld characterization of phase transitions involving polyhedral rotations.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Müller, M.Dinnebier, R.E.Dippel, A.-C.Stokes, H.T.Campbell, B.J.2014-02-22doi:10.1107/S1600576713034560International Union of CrystallographyThe parametric refinement of rotational rigid-body symmetry modes is demonstrated for the cubic monoclinic phase transition in Mg(H2O)6RbBr3.ENrigid-body rotationsymmetry modeirreducible representationparametric refinementphase transitionThe application of rotational symmetry modes to quantitative rigid-body analysis is demonstrated for octahedral rotations in Mg(H2O)6RbBr3. Rigid-body rotations are treated as axial-vector order parameters and projected using group-theoretical methods. The high-temperature crystal structure of the Mg(H2O)6RbBr3 double salt consists of a cubic perovskite-like corner-sharing network of RbBr6 octahedra with isolated MgO6 octahedra at the perovskite A sites. A phase transition occurs at 411 K upon cooling, whereupon the MgO6 octahedra experience a substantial rigid-body rotation, the RbBr6 octahedra are translated but not rotated, and both types of octahedra become slightly distorted. The MgO6 rotation has three orthogonal components associated with the X5−, Γ4+ and X1− irreducible representations of the parent Pm{\overline 3}m space-group symmetry which, given the weakly first-order character of the transition, appear to be strongly coupled. Parametric and sequential refinements of the temperature-dependent structure were conducted using four model types: (1) traditional atomic xyz coordinates for each atom, (2) traditional rigid-body parameters, (3) purely displacive symmetry modes and (4) rigid-body rotational symmetry modes. We demonstrate that rigid-body rotational symmetry modes are an especially effective parameter set for the Rietveld characterization of phase transitions involving polyhedral rotations.text/htmlA symmetry-mode description of rigid-body rotations in crystalline solids: a case study of Mg(H2O)6RbBr3text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers532538Computer models of icosahedral carbon nanostructures (shungite)
http://scripts.iucr.org/cgi-bin/paper?he5636
A universal algorithm for the generation of three-dimensional models of icosahedral fullerene-like carbon nanostructures has been developed. Coordinates of atoms on their surface are calculated and three-dimensional models of fulleroids – nested icosahedra – are built. A flat model consisting of five graphite layers of varying diameters is computed in an attempt to explain the nature of the diffraction maximum (d ≃ 6.81 Å, 2θ ≃ 13°) in shungite carbon by the existence of edge effects, carbon atoms or small fragments of layers in the interlayer space, or dislocation rings.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Pleshakov, V.2014-02-22doi:10.1107/S1600576713033943International Union of CrystallographyA universal algorithm for the generation of three-dimensional models of icosahedral fullerene-like carbon nanostructures has been developed.ENcomputer modelingcarbon nanostructuresshungiteA universal algorithm for the generation of three-dimensional models of icosahedral fullerene-like carbon nanostructures has been developed. Coordinates of atoms on their surface are calculated and three-dimensional models of fulleroids – nested icosahedra – are built. A flat model consisting of five graphite layers of varying diameters is computed in an attempt to explain the nature of the diffraction maximum (d ≃ 6.81 Å, 2θ ≃ 13°) in shungite carbon by the existence of edge effects, carbon atoms or small fragments of layers in the interlayer space, or dislocation rings.text/htmlComputer models of icosahedral carbon nanostructures (shungite)text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers539543Approaches to modelling thermal diffuse scattering in triglycine sulfate, (NH2CH2COOH)3·H2SO4
http://scripts.iucr.org/cgi-bin/paper?kk5156
The thermal diffuse scattering in triglycine sulfate, (NH2CH2COOH)3·H2SO4, has been modelled by treating the intermolecular interactions that give rise to the correlated atomic displacements like Hooke's law springs. To limit the number of variables in the model, the force constants for the interactions were parameterized in a number of ways, the most successful of which was an empirical interaction potential using an exponential function of the interatomic separations.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Hudspeth, J.M.Goossens, D.J.Welberry, T.R.2014-02-22doi:10.1107/S1600576713034547International Union of CrystallographyThe displacive diffuse scattering from triglycine sulfate, (NH2CH2COOH)3·H2SO4, has been modelled using several approaches, to determine which is preferable and as a guide for analysis of similar compounds.ENthermal diffuse scatteringtriglycine sulfatemodellingThe thermal diffuse scattering in triglycine sulfate, (NH2CH2COOH)3·H2SO4, has been modelled by treating the intermolecular interactions that give rise to the correlated atomic displacements like Hooke's law springs. To limit the number of variables in the model, the force constants for the interactions were parameterized in a number of ways, the most successful of which was an empirical interaction potential using an exponential function of the interatomic separations.text/htmlApproaches to modelling thermal diffuse scattering in triglycine sulfate, (NH2CH2COOH)3·H2SO4text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers544551Modelling and quantification of intergrowth in γ-MnO2 by laboratory pair distribution function analysis
http://scripts.iucr.org/cgi-bin/paper?fs5042
γ-MnO2 is a material formed by random intergrowth of two phases, β-MnO2 and R-MnO2. It is demonstrated here on seven γ-MnO2 samples that pair distribution function analysis using a conventional X-ray diffraction setup (Bragg–Brentano geometry with a molybdenum anode) allows the quantification of this intergrowth simply via a simulation of the actual material by a mixture of β-MnO2 and R-MnO2 phases. Although this method does not take into account specifically the relaxed distances in the vicinity of the intergrowth zone, it is found to be very robust, accurate and in full agreement with the widely used quantification based on the empirical approach of Chabre & Pannetier [Prog. Solid State Chem. (1995), 23, 1–130].Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Galliez, K.Deniard, P.Petit, P.-E.Lambertin, D.Bart, F.Jobic, S.2014-02-22doi:10.1107/S1600576714000375International Union of CrystallographyThe application of the atomic pair distribution function for the purpose of obtaining the intergrowth amount of pyrolusite (β-MnO2) and ramsdellite (R-MnO2) in γ-MnO2 is demonstrated. The presented model opens the door to intergrowth quantification in numerous materials where the two structural components are clearly distinguishable.ENpair distribution functionmanganese oxidesintergrowthquantificationγ-MnO2 is a material formed by random intergrowth of two phases, β-MnO2 and R-MnO2. It is demonstrated here on seven γ-MnO2 samples that pair distribution function analysis using a conventional X-ray diffraction setup (Bragg–Brentano geometry with a molybdenum anode) allows the quantification of this intergrowth simply via a simulation of the actual material by a mixture of β-MnO2 and R-MnO2 phases. Although this method does not take into account specifically the relaxed distances in the vicinity of the intergrowth zone, it is found to be very robust, accurate and in full agreement with the widely used quantification based on the empirical approach of Chabre & Pannetier [Prog. Solid State Chem. (1995), 23, 1–130].text/htmlModelling and quantification of intergrowth in γ-MnO2 by laboratory pair distribution function analysistext2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers552560Robust structure and morphology parameters for CdS nanoparticles by combining small-angle X-ray scattering and atomic pair distribution function data in a complex modeling framework
http://scripts.iucr.org/cgi-bin/paper?nb5094
In this work, the concept of complex modeling (CM) is tested by carrying out a co-refinement of the atomic pair distribution function and small-angle X-ray scattering data from CdS nanoparticles. It is shown that, compared with either single technique alone, the CM approach yields a more accurate and robust structural insight into the atomic structure and morphology of nanoparticles. This work opens the door for the application of CM to a wider class of nanomaterials and for the incorporation of additional experimental and theoretical techniques into these studies.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Farrow, C.Shi, C.Juhás, P.Peng, X.Billinge, S. L. J.2014-03-11doi:10.1107/S1600576713034055International Union of CrystallographyA complex modeling approach that combines atomic pair distribution function and small-angle X-ray scattering data from CdS quantum dots yields more robust and accurate structural and morphological parameters when compared with either single technique alone.ENsmall-angle X-ray scatteringCdS nanoparticlescomplex modelingatomic pair distribution functionIn this work, the concept of complex modeling (CM) is tested by carrying out a co-refinement of the atomic pair distribution function and small-angle X-ray scattering data from CdS nanoparticles. It is shown that, compared with either single technique alone, the CM approach yields a more accurate and robust structural insight into the atomic structure and morphology of nanoparticles. This work opens the door for the application of CM to a wider class of nanomaterials and for the incorporation of additional experimental and theoretical techniques into these studies.text/htmlRobust structure and morphology parameters for CdS nanoparticles by combining small-angle X-ray scattering and atomic pair distribution function data in a complex modeling frameworktext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers561565Temperature-dependent optical rotatory power in the presence of birefringence of KTA and KTP crystals by the high-accuracy universal polarimeter method at 632.8 nm wavelength
http://scripts.iucr.org/cgi-bin/paper?ks5408
Temperature-dependent simultaneous measurement of birefringence and optical rotatory power (ORP) for orthorhombic crystals of potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) has been achieved by using the high-accuracy universal polarimeter method at 632.8 nm wavelength. The birefringence and ORP changes along the (110) planes for KTA and KTP crystals were found to have a nearly parabolic form for the temperature range 297–493 K. The thermal variation coefficients were found to be 0.9 (5) × 10−5 K−1 and 5.6 (3) × 10−8 K−2 for KTA and 0.9 (5) × 10−5 K−1 and 5.7 (3) × 10−8 K−2 for KTP. The ORPs at 297 K were found to be 20.0 (20) and 20.5 (15)° mm−1 for KTA and KTP, respectively. The thermal variation coefficients of the ORP were found to be 1.8 (2) × 10−3° mm−1 K−1 and 1.1 (1) × 10–5° mm−1 K−2 for KTA and 1.9 (2) × 10−3° mm−1 K−1 and 1.2 (1) × 10−5° mm−1 K−2 for KTP.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Hernández-Rodríguez, C.Fragoso-López, A.B.Herreros-Cedrés, J.Guerrero-Lemus, R.2014-03-11doi:10.1107/S1600576714000454International Union of CrystallographyTemperature-dependent optical rotatory power can give valuable information on the achiral optical properties of orthorhombic crystals of which only a few measurements are known. The high-accuracy universal polarimeter technique was successfully applied to determine the optical rotation in the presence of birefringence of potassium titanyl arsenate (KTA) and potassium titanyl phosphate (KTP) biaxial crystals.ENoptical rotatory powerorthorhombic crystalsbirefringenceTemperature-dependent simultaneous measurement of birefringence and optical rotatory power (ORP) for orthorhombic crystals of potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) has been achieved by using the high-accuracy universal polarimeter method at 632.8 nm wavelength. The birefringence and ORP changes along the (110) planes for KTA and KTP crystals were found to have a nearly parabolic form for the temperature range 297–493 K. The thermal variation coefficients were found to be 0.9 (5) × 10−5 K−1 and 5.6 (3) × 10−8 K−2 for KTA and 0.9 (5) × 10−5 K−1 and 5.7 (3) × 10−8 K−2 for KTP. The ORPs at 297 K were found to be 20.0 (20) and 20.5 (15)° mm−1 for KTA and KTP, respectively. The thermal variation coefficients of the ORP were found to be 1.8 (2) × 10−3° mm−1 K−1 and 1.1 (1) × 10–5° mm−1 K−2 for KTA and 1.9 (2) × 10−3° mm−1 K−1 and 1.2 (1) × 10−5° mm−1 K−2 for KTP.text/htmlTemperature-dependent optical rotatory power in the presence of birefringence of KTA and KTP crystals by the high-accuracy universal polarimeter method at 632.8 nm wavelengthtext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers566574A method for accurate texture determination of thin oxide films by glancing-angle laboratory X-ray diffraction
http://scripts.iucr.org/cgi-bin/paper?rw5072
The present article describes a modification to the standard method of glancing-angle X-ray diffraction for accurate measurement of the texture of thin oxide films. The technique resolves the problems caused by overlapping diffraction peaks originating from multiphase materials with asymmetric unit cells and the peak broadening associated with sample tilt during glancing-angle texture measurement. The entire 2θ range of interest is recorded as a function of sample orientation, and the integrated intensities from different crystallographic planes are extracted from fitted diffraction profiles. The technique allows for pole figures to be plotted from diffraction peaks that could otherwise not be resolved and separates contributions from neighbouring peaks, leading to a more accurate representation of the existing oxide texture. The proposed method has been used for determining texture in a 3 µm layer of monoclinic/tetragonal zirconium oxide grown during aqueous corrosion testing and has been verified by additional synchrotron X-ray diffraction measurements.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Garner, A.Preuss, M.Frankel, P.2014-03-11doi:10.1107/S1600576714000569International Union of CrystallographyA method for accurate measurement of the texture of thin oxide films has been proposed. The method involves the separation of integrated intensities from complex glancing-angle diffraction spectra and leads to an improved representation of the preferred orientation present in oxide films.ENtexturethin oxide filmsglancing-angle X-ray diffractionThe present article describes a modification to the standard method of glancing-angle X-ray diffraction for accurate measurement of the texture of thin oxide films. The technique resolves the problems caused by overlapping diffraction peaks originating from multiphase materials with asymmetric unit cells and the peak broadening associated with sample tilt during glancing-angle texture measurement. The entire 2θ range of interest is recorded as a function of sample orientation, and the integrated intensities from different crystallographic planes are extracted from fitted diffraction profiles. The technique allows for pole figures to be plotted from diffraction peaks that could otherwise not be resolved and separates contributions from neighbouring peaks, leading to a more accurate representation of the existing oxide texture. The proposed method has been used for determining texture in a 3 µm layer of monoclinic/tetragonal zirconium oxide grown during aqueous corrosion testing and has been verified by additional synchrotron X-ray diffraction measurements.text/htmlA method for accurate texture determination of thin oxide films by glancing-angle laboratory X-ray diffractiontext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers575583Towards a high-throughput system for high-pressure cooling of cryoprotectant-free biological crystals
http://scripts.iucr.org/cgi-bin/paper?to5058
A prototype of a high-pressure cooling apparatus dedicated to macromolecular crystallography on synchrotrons is reported. The system allows cooling of biological crystals without the addition of penetrating or nonpenetrating exogenous cryoprotectant by transforming the aqueous solvent into high-density amorphous ice at a pressure of 200 MPa. The samples are directly fished from crystallization trays with cryopins specifically designed for the pressurizing device and which are compatible with robotized sample changers on synchrotron beamlines. Optionally, the system allows noble gas derivatization during the high-pressure cooling procedure. Some technical details of the equipment and of the method are described in this article. A representative series of test crystals shows that the system is capable of successfully cooling samples that normally require a wide variety of cryoprotection conditions. The last section focuses on pressure-induced structural modifications of these proteins, which are shown to be few but nevertheless of interest.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Linden, P. van derDobias, F.Vitoux, H.Kapp, U.Jacobs, J.Mc Sweeney, S.Mueller-Dieckmann, C.Carpentier, P.2014-03-11doi:10.1107/S1600576714000855International Union of CrystallographyA high-pressure system for cooling cryoprotectant-free biological crystals has been designed for automated data collection on synchrotrons. The apparatus and the method have been validated with a series of test samples.ENprotein crystallographyhigh-pressure crystallographycryocrystallographycryoprotectionA prototype of a high-pressure cooling apparatus dedicated to macromolecular crystallography on synchrotrons is reported. The system allows cooling of biological crystals without the addition of penetrating or nonpenetrating exogenous cryoprotectant by transforming the aqueous solvent into high-density amorphous ice at a pressure of 200 MPa. The samples are directly fished from crystallization trays with cryopins specifically designed for the pressurizing device and which are compatible with robotized sample changers on synchrotron beamlines. Optionally, the system allows noble gas derivatization during the high-pressure cooling procedure. Some technical details of the equipment and of the method are described in this article. A representative series of test crystals shows that the system is capable of successfully cooling samples that normally require a wide variety of cryoprotection conditions. The last section focuses on pressure-induced structural modifications of these proteins, which are shown to be few but nevertheless of interest.text/htmlTowards a high-throughput system for high-pressure cooling of cryoprotectant-free biological crystalstext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers584592Robust powder auto-indexing using many peaks
http://scripts.iucr.org/cgi-bin/paper?fs5064
A new powder auto-indexing method for the CONOGRAPH software [Oishi-Tomiyasu (2013). Acta Cryst. A69, 603–610] can carry out exhaustive powder auto-indexing in a short time, even if the q values of many peaks are used, with sufficient consideration given to their observational errors. This article explains that the use of many q values is essential to make powder auto-indexing robust against dominant zones and missing or false peaks in the input. Results from CONOGRAPH for 25 real diffraction patterns, including difficult cases, are presented. Owing to a sorting criterion for zones defined in the previous article, the computation times were reduced by a factor of between 18 and 250, and exhaustive powder auto-indexing was completed in 5 min at most.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Oishi-Tomiyasu, R.2014-03-11doi:10.1107/S1600576714000922International Union of CrystallographyA new algorithm, CONOGRAPH, carries out exhaustive powder auto-indexing in a short time, even if the q values of many peaks are used for robust powder auto-indexing. Some results from CONOGRAPH are presented.ENpowder auto-indexingdominant zonesalgorithmsCONOGRAPHA new powder auto-indexing method for the CONOGRAPH software [Oishi-Tomiyasu (2013). Acta Cryst. A69, 603–610] can carry out exhaustive powder auto-indexing in a short time, even if the q values of many peaks are used, with sufficient consideration given to their observational errors. This article explains that the use of many q values is essential to make powder auto-indexing robust against dominant zones and missing or false peaks in the input. Results from CONOGRAPH for 25 real diffraction patterns, including difficult cases, are presented. Owing to a sorting criterion for zones defined in the previous article, the computation times were reduced by a factor of between 18 and 250, and exhaustive powder auto-indexing was completed in 5 min at most.text/htmlRobust powder auto-indexing using many peakstext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers593598Neutron diffraction studies of a double-crystal (+n,–m) setting containing a fully asymmetric diffraction geometry of a bent perfect crystal with output beam expansion
http://scripts.iucr.org/cgi-bin/paper?kk5150
The neutron diffraction properties of a double-crystal (+n,−m) setting, which contains a bent perfect Si(311) crystal in the fully asymmetric diffraction (FAD) geometry with output beam expansion and a bent perfect Si(220) crystal in the symmetric diffraction geometry, are presented. Generally, there are two possibilities for the FAD geometry: either with output beam compression or with output beam expansion. In this case, attention has been focused on the latter. The properties of the (+n,−m) double-bent-crystal arrangement of a bent perfect crystal FAD Si(311) geometry, in combination with a bent Si(220) crystal slab in the symmetric diffraction geometry, were studied. It was found that, after beam expansion, this FAD geometry can provide a monochromatic beam of rather large cross section but very small divergence.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Mikula, P.Vrána, M.Pilch, J.Seok Seong, B.Woo, W.Em, V.2014-03-11doi:10.1107/S1600576714001964International Union of CrystallographyThis article desribes the neutron diffraction properties of a double-crystal (+n,−m) setting, which contains a bent perfect Si(311) crystal in the fully asymmetric diffraction (FAD) geometry with output beam expansion and a bent perfect Si(220) crystal in the symmetric diffraction geometry. After beam expansion, this FAD geometry provides a beam of large cross section but small divergence.ENneutron diffractionbent perfect crystalsfully asymmetric diffractionThe neutron diffraction properties of a double-crystal (+n,−m) setting, which contains a bent perfect Si(311) crystal in the fully asymmetric diffraction (FAD) geometry with output beam expansion and a bent perfect Si(220) crystal in the symmetric diffraction geometry, are presented. Generally, there are two possibilities for the FAD geometry: either with output beam compression or with output beam expansion. In this case, attention has been focused on the latter. The properties of the (+n,−m) double-bent-crystal arrangement of a bent perfect crystal FAD Si(311) geometry, in combination with a bent Si(220) crystal slab in the symmetric diffraction geometry, were studied. It was found that, after beam expansion, this FAD geometry can provide a monochromatic beam of rather large cross section but very small divergence.text/htmlNeutron diffraction studies of a double-crystal (+n,–m) setting containing a fully asymmetric diffraction geometry of a bent perfect crystal with output beam expansiontext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers599605Crystallographic effect of a high magnetic field on a solidified hypoeutectic Zn–Al alloy
http://scripts.iucr.org/cgi-bin/paper?nb5082
Hypoeutectic Zn–4.45 wt% Al solidified under a high magnetic field was investigated crystallographically. With the field, the primary zinc-rich β phase is distributed homogeneously and orients with the c axis perpendicular to the magnetic field direction. These results are attributed to the magnetic viscosity resistance force and the magnetocrystalline anisotropy of zinc, respectively. The orientation modification also leads to a preferential alignment of the flat-shaped primary β dendrites. Furthermore, with the field, the eutectic β phase shows an orientation character similar to that of the primary β phase. This arises from its continuous growth with the primary β phase. In addition, a specific crystallographic orientation relationship ({0001}β||{111}α, 〈1\overline 210〉β||〈110〉α) exists in some of the eutectics (between the eutectic zinc-rich β and aluminium-rich α phases). However, this orientation relationship is related to the distribution of primary β dendrites, which originates from the independent nucleation of the pseudo-primary α phase attached to the primary β dendrites.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Li, L.Li, Z.Zhang, Y.Esling, C.Liu, H.Zhao, Z.Zhu, Q.Zuo, Y.Cui, J.2014-03-11doi:10.1107/S1600576714001939International Union of CrystallographyCrystallographic features of a hypoeutectic Zn–Al alloy were significantly affected by the presence of a high magnetic field during the solidification process.ENhypoeutectic Zn–Alhigh magnetic fieldssolidificationelectron backscatter diffractionHypoeutectic Zn–4.45 wt% Al solidified under a high magnetic field was investigated crystallographically. With the field, the primary zinc-rich β phase is distributed homogeneously and orients with the c axis perpendicular to the magnetic field direction. These results are attributed to the magnetic viscosity resistance force and the magnetocrystalline anisotropy of zinc, respectively. The orientation modification also leads to a preferential alignment of the flat-shaped primary β dendrites. Furthermore, with the field, the eutectic β phase shows an orientation character similar to that of the primary β phase. This arises from its continuous growth with the primary β phase. In addition, a specific crystallographic orientation relationship ({0001}β||{111}α, 〈1\overline 210〉β||〈110〉α) exists in some of the eutectics (between the eutectic zinc-rich β and aluminium-rich α phases). However, this orientation relationship is related to the distribution of primary β dendrites, which originates from the independent nucleation of the pseudo-primary α phase attached to the primary β dendrites.text/htmlCrystallographic effect of a high magnetic field on a solidified hypoeutectic Zn–Al alloytext2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers606612On the assessment by grazing-incidence small-angle X-ray scattering of replica quality in polymer gratings fabricated by nanoimprint lithography
http://scripts.iucr.org/cgi-bin/paper?rg5059
Grazing-incidence small-angle X-ray scattering (GISAXS) can be used to characterize the replica quality of polymer gratings prepared by thermal nanoimprint lithography (NIL). Here it is shown using GISAXS experiments that a series of NIL polymer gratings with different line quality present characteristic features that can be associated with the level of defects per line. Both stamps and NIL polymer gratings exhibit characteristic semicircle-like GISAXS patterns. However NIL polymer gratings with defective lines exhibit GISAXS patterns with an excess of diffuse scattering as compared to those of the corresponding stamps. In a first approach, this effect is attributed to a reduction of the effective length of the lines diffracting coherently as the number of defects per line increases.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Soccio, M.Alayo, N.Martín-Fabiani, I.Rueda, D.R.García-Gutiérrez, M.C.Rebollar, E.Martínez-Tong, D.E.Pérez-Murano, F.Ezquerra, T.A.2014-03-19doi:10.1107/S160057671400168XInternational Union of CrystallographyIt is shown using grazing-incidence small-angle X-ray scattering experiments that a series of NIL polymer gratings with different line quality present characteristic features that can be associated with the level of defects per line.ENgrazing-incidence small-angle X-ray scatteringpolymer gratingsnanoimprint lithographyGrazing-incidence small-angle X-ray scattering (GISAXS) can be used to characterize the replica quality of polymer gratings prepared by thermal nanoimprint lithography (NIL). Here it is shown using GISAXS experiments that a series of NIL polymer gratings with different line quality present characteristic features that can be associated with the level of defects per line. Both stamps and NIL polymer gratings exhibit characteristic semicircle-like GISAXS patterns. However NIL polymer gratings with defective lines exhibit GISAXS patterns with an excess of diffuse scattering as compared to those of the corresponding stamps. In a first approach, this effect is attributed to a reduction of the effective length of the lines diffracting coherently as the number of defects per line increases.text/htmlOn the assessment by grazing-incidence small-angle X-ray scattering of replica quality in polymer gratings fabricated by nanoimprint lithographytext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers613618Combined fitting of small- and wide-angle X-ray total scattering data from nanoparticles: benefits and issues
http://scripts.iucr.org/cgi-bin/paper?to5066
Simultaneous fitting of small- (SAS) and wide-angle (WAS) X-ray total scattering data for nanoparticles has been explored using both simulated and experimental signals. The nanoparticle types included core/shell metal and quantum-dot CdSe systems. Various combinations of reciprocal- and real-space representations of the scattering data have been considered. Incorporating SAS data into the fit consistently returned more accurate particle-size distribution parameters than those obtained by fitting the WAS data alone. A popular method for fitting the Fourier transform of the WAS data (i.e. a pair-distribution function), in which the omitted SAS part is represented using a parametric function, typically yielded significantly incorrect results. The Pareto optimization method combined with a genetic algorithm proved to be effective for simultaneous SAS/WAS analyses. An approach for identifying the most optimal solution from the Pareto set of solutions has been proposed.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Gagin, A.Allen, A.J.Levin, I.2014-03-19doi:10.1107/S1600576714001046International Union of CrystallographySimultaneous fitting of small- and wide-angle neutron/X-ray total scattering data for nanoparticles has been evaluated using both simulated and experimental signals. ENsmall- and wide-angle X-ray scatteringnanoparticlesSimultaneous fitting of small- (SAS) and wide-angle (WAS) X-ray total scattering data for nanoparticles has been explored using both simulated and experimental signals. The nanoparticle types included core/shell metal and quantum-dot CdSe systems. Various combinations of reciprocal- and real-space representations of the scattering data have been considered. Incorporating SAS data into the fit consistently returned more accurate particle-size distribution parameters than those obtained by fitting the WAS data alone. A popular method for fitting the Fourier transform of the WAS data (i.e. a pair-distribution function), in which the omitted SAS part is represented using a parametric function, typically yielded significantly incorrect results. The Pareto optimization method combined with a genetic algorithm proved to be effective for simultaneous SAS/WAS analyses. An approach for identifying the most optimal solution from the Pareto set of solutions has been proposed.text/htmlCombined fitting of small- and wide-angle X-ray total scattering data from nanoparticles: benefits and issuestext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers619629Moroccan ornamental quasiperiodic patterns constructed by the multigrid method
http://scripts.iucr.org/cgi-bin/paper?sc5069
The similarity between the structure of Islamic decorative patterns and quasicrystals has aroused the interest of several crystallographers. Many of these patterns have been analysed by different approaches, including various kinds of ornamental quasiperiodic patterns encountered in Morocco and the Alhambra (Andalusia), as well as those in the eastern Islamic world. In the present work, the interest is in the quasiperiodic patterns found in several Moroccan historical buildings constructed in the 14th century. First, the zellige panels (fine mosaics) decorating the Madrasas (schools) Attarine and Bou Inania in Fez are described in terms of Penrose tiling, to confirm that both panels have a quasiperiodic structure. The multigrid method developed by De Bruijn [Proc. K. Ned. Akad. Wet. Ser. A Math. Sci. (1981), 43, 39–66] and reformulated by Gratias [Tangente (2002), 85, 34–36] to obtain a quasiperiodic paving is then used to construct known quasiperiodic patterns from periodic patterns extracted from the Madrasas Bou Inania and Ben Youssef (Marrakech). Finally, a method of construction of heptagonal, enneagonal, tetradecagonal and octadecagonal quasiperiodic patterns, not encountered in Moroccan ornamental art, is proposed. They are built from tilings (skeletons) generated by the multigrid method and decorated by motifs obtained by craftsmen.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Aboufadil, Y.Thalal, A.Raghni, M.A.E.I.2014-03-19doi:10.1107/S1600576714001691International Union of CrystallographyQuasiperiodic tilings constructed by the multigrid method and decorated by rosettes constructed by craftsmen are studied.ENquasiperiodic patternsIslamic artmultigrid methodscraftsmen's methodsThe similarity between the structure of Islamic decorative patterns and quasicrystals has aroused the interest of several crystallographers. Many of these patterns have been analysed by different approaches, including various kinds of ornamental quasiperiodic patterns encountered in Morocco and the Alhambra (Andalusia), as well as those in the eastern Islamic world. In the present work, the interest is in the quasiperiodic patterns found in several Moroccan historical buildings constructed in the 14th century. First, the zellige panels (fine mosaics) decorating the Madrasas (schools) Attarine and Bou Inania in Fez are described in terms of Penrose tiling, to confirm that both panels have a quasiperiodic structure. The multigrid method developed by De Bruijn [Proc. K. Ned. Akad. Wet. Ser. A Math. Sci. (1981), 43, 39–66] and reformulated by Gratias [Tangente (2002), 85, 34–36] to obtain a quasiperiodic paving is then used to construct known quasiperiodic patterns from periodic patterns extracted from the Madrasas Bou Inania and Ben Youssef (Marrakech). Finally, a method of construction of heptagonal, enneagonal, tetradecagonal and octadecagonal quasiperiodic patterns, not encountered in Moroccan ornamental art, is proposed. They are built from tilings (skeletons) generated by the multigrid method and decorated by motifs obtained by craftsmen.text/htmlMoroccan ornamental quasiperiodic patterns constructed by the multigrid methodtext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers630641Small-angle scattering from polydisperse particles with a diffusive surface
http://scripts.iucr.org/cgi-bin/paper?fs5059
Particles with a diffusive surface, characterized by a deviation from the Porod power-law asymptotic behavior in small-angle scattering towards an exponent below −4, are considered with respect to the polydispersity problem. The case of low diffusivity is emphasized, which allows the description of the scattering length density distribution within spherically isotropic particles in terms of a continuous profile. This significantly simplifies the analysis of the particle-size distribution function, as well as the change in the scattering invariants under contrast variation. The effect of the solvent scattering contribution on the apparent exponent value in power-law-type scattering and related restrictions in the analysis of the scattering curves are discussed. The principal features and possibilities of the developed approach are illustrated in the treatment of experimental small-angle neutron scattering data from liquid dispersions of detonation nanodiamond. The obtained scattering length density profile of the particles fits well with a transition of the diamond states of carbon inside the crystallites to graphite-like states at the surface, and it is possible to combine the diffusive properties of the surface with the experimental shift of the mean scattering length density of the particles compared with that of pure diamond. The moments of the particle-size distribution are derived and analyzed in terms of the lognormal approximation.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Tomchuk, O.V.Bulavin, L.A.Aksenov, V.L.Garamus, V.M.Ivankov, O.I.Vul', A.Y.Dideikin, A.T.Avdeev, M.V.2014-03-19doi:10.1107/S1600576714001216International Union of CrystallographySmall-angle scattering from polydisperse non-homogeneous particles with a diffusive interface is considered for the case of low diffusivity. The deduced simplifications in the analysis of both the polydispersity and the inner structure (contrast variation) of the particles are used in the treatment of small-angle neutron scattering data from liquid dispersions of detonation nanodiamond.ENsmall-angle neutron scatteringpolydisperse systemsdiffusive interfacescontrast variationdetonation nanodiamondnanocrystallitesliquid dispersionsParticles with a diffusive surface, characterized by a deviation from the Porod power-law asymptotic behavior in small-angle scattering towards an exponent below −4, are considered with respect to the polydispersity problem. The case of low diffusivity is emphasized, which allows the description of the scattering length density distribution within spherically isotropic particles in terms of a continuous profile. This significantly simplifies the analysis of the particle-size distribution function, as well as the change in the scattering invariants under contrast variation. The effect of the solvent scattering contribution on the apparent exponent value in power-law-type scattering and related restrictions in the analysis of the scattering curves are discussed. The principal features and possibilities of the developed approach are illustrated in the treatment of experimental small-angle neutron scattering data from liquid dispersions of detonation nanodiamond. The obtained scattering length density profile of the particles fits well with a transition of the diamond states of carbon inside the crystallites to graphite-like states at the surface, and it is possible to combine the diffusive properties of the surface with the experimental shift of the mean scattering length density of the particles compared with that of pure diamond. The moments of the particle-size distribution are derived and analyzed in terms of the lognormal approximation.text/htmlSmall-angle scattering from polydisperse particles with a diffusive surfacetext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers642653Absolute scale calibration with use of excess scattering length for small-angle X-ray scattering
http://scripts.iucr.org/cgi-bin/paper?he5637
For small-angle X-ray scattering (SAXS) in solution, absolute intensity calibration is an important step to estimate the number of electrons of the sample. In this study, the excess scattering length of 1-bromododecane dispersed in dodecane was determined using that of 1-chlorododecane in the same solvent. The deviation of the experimental values from theoretical calculations obtained using atomic factors was around 1%. It is suggested that the 1-chlorododecane–dodecane system constitutes a new calibration approach that is applicable to various materials over a large energy range generally used in SAXS measurements, and could be less complex and more reliable than conventional methods.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Ohta, N.Sekiguchi, H.Sasaki, Y.C.Yagi, N.2014-03-19doi:10.1107/S1600576714002210International Union of Crystallography1-Chlorododecane dispersed in dodecane is proposed as an absolute scale calibration standard substance for small-angle X-ray scattering.ENsmall-angle X-ray scatteringSAXSabsolute scale calibration1-chlorododecane1-bromododecanedodecaneFor small-angle X-ray scattering (SAXS) in solution, absolute intensity calibration is an important step to estimate the number of electrons of the sample. In this study, the excess scattering length of 1-bromododecane dispersed in dodecane was determined using that of 1-chlorododecane in the same solvent. The deviation of the experimental values from theoretical calculations obtained using atomic factors was around 1%. It is suggested that the 1-chlorododecane–dodecane system constitutes a new calibration approach that is applicable to various materials over a large energy range generally used in SAXS measurements, and could be less complex and more reliable than conventional methods.text/htmlAbsolute scale calibration with use of excess scattering length for small-angle X-ray scatteringtext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers654658Simultaneous determination of several crystal structures from powder mixtures: the combination of powder X-ray diffraction, band-target entropy minimization and Rietveld methods
http://scripts.iucr.org/cgi-bin/paper?to5064
Crystal structure determination is the key to a detailed understanding of crystalline materials and their properties. This requires either single crystals or high-quality single-phase powder X-ray diffraction data. The present contribution demonstrates a novel method to reconstruct single-phase powder diffraction data from diffraction patterns of mixtures of several components and subsequently to determine the individual crystal structures. The new method does not require recourse to any database of known materials but relies purely on numerical separation of the mixture data into individual component diffractograms. The resulting diffractograms can subsequently be treated like single-phase powder diffraction data, i.e. indexing, structure solution and Rietveld refinement. This development opens up a host of new opportunities in materials science and related areas. For example, crystal structures can now be determined at much earlier stages when only impure samples or polymorphic mixtures are available.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Schreyer, M.Guo, L.Thirunahari, S.Gao, F.Garland, M.2014-03-19doi:10.1107/S1600576714003379International Union of CrystallographyBy collecting multiple mixture powder diffractograms and deconvoluting them into the individual components using the band target entropy minimization algorithm, single-phase powder diffractograms are obtained. From these, structure solutions and refinements are achieved with standard crystallographic techniques.ENpowder X-ray diffractionband target entropy minimizationmixture analysisstructure solutionpolymorphismCrystal structure determination is the key to a detailed understanding of crystalline materials and their properties. This requires either single crystals or high-quality single-phase powder X-ray diffraction data. The present contribution demonstrates a novel method to reconstruct single-phase powder diffraction data from diffraction patterns of mixtures of several components and subsequently to determine the individual crystal structures. The new method does not require recourse to any database of known materials but relies purely on numerical separation of the mixture data into individual component diffractograms. The resulting diffractograms can subsequently be treated like single-phase powder diffraction data, i.e. indexing, structure solution and Rietveld refinement. This development opens up a host of new opportunities in materials science and related areas. For example, crystal structures can now be determined at much earlier stages when only impure samples or polymorphic mixtures are available.text/htmlSimultaneous determination of several crystal structures from powder mixtures: the combination of powder X-ray diffraction, band-target entropy minimization and Rietveld methodstext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers659667986780986781986782986783986784986785986786986787986788LCDiXRay: a user-friendly program for powder diffraction indexing of columnar liquid crystals
http://scripts.iucr.org/cgi-bin/paper?nb5093
The formulation of a standard computerized procedure for the indexing of powder X-ray diffraction (PXRD) patterns of columnar liquid crystals, with the determination of all structural information extracted from a properly indexed PXRD spectrum and the attribution of the columnar mesophase symmetry, is presented. In particular, the proposed program notably accelerates the identification of columnar mesophases together with the in situ determination of their structural parameters such as mesophase type, space group, cell parameters, cross-section area, intermolecular stacking distance between consecutive discoids and, in the case of ordered mesophases, the estimation of the number of molecules constituting each discoid.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Godbert, N.Crispini, A.Ghedini, M.Carini, M.Chiaravalloti, F.Ferrise, A.2014-03-19doi:10.1107/S1600576714003240International Union of CrystallographyLCDiXRay, a user-friendly program for the indexing of powder X-ray diffraction patterns of columnar liquid crystals, is presented. The program allows straightforward determination of structural parameters of columnar mesophases.ENcolumnar liquid crystalsdiscoticspowder X-ray diffractioncomputer programsThe formulation of a standard computerized procedure for the indexing of powder X-ray diffraction (PXRD) patterns of columnar liquid crystals, with the determination of all structural information extracted from a properly indexed PXRD spectrum and the attribution of the columnar mesophase symmetry, is presented. In particular, the proposed program notably accelerates the identification of columnar mesophases together with the in situ determination of their structural parameters such as mesophase type, space group, cell parameters, cross-section area, intermolecular stacking distance between consecutive discoids and, in the case of ordered mesophases, the estimation of the number of molecules constituting each discoid.text/htmlLCDiXRay: a user-friendly program for powder diffraction indexing of columnar liquid crystalstext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers668679Patterson analysis for layer profile determination by neutron or X-ray reflectometry. II
http://scripts.iucr.org/cgi-bin/paper?ks5386
A data analysis technique based on the Patterson function is tested with simulated X-ray reflectometry data. In comparison to the case for neutron reflectometry, additional data manipulation is required because the scattering-length density of materials is generally much higher for X-rays than for neutrons. With this extra step duly performed, the technique yields a model layer profile accurate enough for least-squares refinement.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Tun, Z.2014-03-19doi:10.1107/S1600576714004464International Union of CrystallographyA way of determining layer structure in terms of Patterson analysis is demonstrated for a simulated X-ray reflectometry measurement. This article is the sequel to a recent publication where the technique was demonstrated for neutron reflectometry.ENX-ray reflectometrylayer profile determinationPatterson analysisA data analysis technique based on the Patterson function is tested with simulated X-ray reflectometry data. In comparison to the case for neutron reflectometry, additional data manipulation is required because the scattering-length density of materials is generally much higher for X-rays than for neutrons. With this extra step duly performed, the technique yields a model layer profile accurate enough for least-squares refinement.text/htmlPatterson analysis for layer profile determination by neutron or X-ray reflectometry. IItext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers680683Metastable adaptive orthorhombic martensite in zirconia nanoparticles
http://scripts.iucr.org/cgi-bin/paper?ks5381
Reported here are observations of isolated orthorhombic (o) ZrO2 nanoparticles (NPs) in the Pbca space group under atmospheric conditions. These NPs are composed of o domains separated by internal semi-coherent boundaries. They are identified to transform from lamellar-twinned tetragonal (t) NPs. The constraining effect of the twin boundaries impedes a direct martensitic transformation to the monoclinic (m) phase but favours a transformation to the o phase. The internal boundaries are considered to evolve from the lamellar-twinning boundaries, playing an important role in the stabilization of the o structure under atmospheric conditions. The observed o structure should be an adaptive martensite transformed from the t phase, different from the general consideration of the o phase as an intermediate stage. A new lattice correspondence (LC) relationship of (011)o||(100)t and [100]o||[001]t is determined for the t-to-o transformation. A possible transformation path is proposed to be t (space group P42/nmc) to o (Pbcm or Pbc21, named oA) to o (Pbca, named oB), and the LC relationship is identified to be (100)t||(100)oA||(011)oB and [001]t||[010]oA||[100]oB.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Liu, S.Hu, W.Zhang, Y.Xiang, J.Wen, F.Xu, B.He, J.Yu, D.Tian, Y.Liu, Z.2014-03-19doi:10.1107/S1600576714003331International Union of CrystallographyOwing to the constraint of the twinning interface in tetragonal zirconia nanoparticles, the martensitic transformation induces an adaptive Pbca orthorhombic phase before finally transforming to the monoclinic phase.ENzirconia nanoparticlesconstrained martensitic transformationorthorhombic phasesinterfacestwinningReported here are observations of isolated orthorhombic (o) ZrO2 nanoparticles (NPs) in the Pbca space group under atmospheric conditions. These NPs are composed of o domains separated by internal semi-coherent boundaries. They are identified to transform from lamellar-twinned tetragonal (t) NPs. The constraining effect of the twin boundaries impedes a direct martensitic transformation to the monoclinic (m) phase but favours a transformation to the o phase. The internal boundaries are considered to evolve from the lamellar-twinning boundaries, playing an important role in the stabilization of the o structure under atmospheric conditions. The observed o structure should be an adaptive martensite transformed from the t phase, different from the general consideration of the o phase as an intermediate stage. A new lattice correspondence (LC) relationship of (011)o||(100)t and [100]o||[001]t is determined for the t-to-o transformation. A possible transformation path is proposed to be t (space group P42/nmc) to o (Pbcm or Pbc21, named oA) to o (Pbca, named oB), and the LC relationship is identified to be (100)t||(100)oA||(011)oB and [001]t||[010]oA||[100]oB.text/htmlMetastable adaptive orthorhombic martensite in zirconia nanoparticlestext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers684691Protein crystal harvesting using the RodBot: a wireless mobile microrobot
http://scripts.iucr.org/cgi-bin/paper?fs5060
A new micro-agent is proposed to assist in automated protein crystal harvesting. The microrobot, named the RodBot, is a wireless mobile device driven by rotating magnetic fields (field strength 5–10 mT). When the RodBot rolls on a substrate in a low Reynolds number liquid environment, it generates flows to lift up and trap crystals in a vortex above itself. The gentle fluidic force acting on the crystals is in the range of a few nanonewtons to tens of nanonewtons and is spread over the whole surface of the crystal. The RodBot is capable of trapping protein crystals ranging from a few micrometres to sub-millimetre size. The trapped crystal can be transported to and deposited onto a loop positioned to accept it, obviating the need for more complicated `fishing' systems dependent on particular motions of the loop, the presence of further manipulators or the use of mechanical grippers. The RodBot can be driven in 24- and 96-well plates or in a crystal soaking dish, making the system compatible with existing crystallization hardware.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Tung, H.-W.Sargent, D.F.Nelson, B.J.2014-03-19doi:10.1107/S1600576714004403International Union of CrystallographyA new wireless microdevice manipulates protein crystals using gentle fluid flow. The microrobot is capable of selecting a single crystal from a group and transporting it onto a loop.ENcrystal harvestingwireless microrobotsmicromanipulationA new micro-agent is proposed to assist in automated protein crystal harvesting. The microrobot, named the RodBot, is a wireless mobile device driven by rotating magnetic fields (field strength 5–10 mT). When the RodBot rolls on a substrate in a low Reynolds number liquid environment, it generates flows to lift up and trap crystals in a vortex above itself. The gentle fluidic force acting on the crystals is in the range of a few nanonewtons to tens of nanonewtons and is spread over the whole surface of the crystal. The RodBot is capable of trapping protein crystals ranging from a few micrometres to sub-millimetre size. The trapped crystal can be transported to and deposited onto a loop positioned to accept it, obviating the need for more complicated `fishing' systems dependent on particular motions of the loop, the presence of further manipulators or the use of mechanical grippers. The RodBot can be driven in 24- and 96-well plates or in a crystal soaking dish, making the system compatible with existing crystallization hardware.text/htmlProtein crystal harvesting using the RodBot: a wireless mobile microrobottext2472014-03-19Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers692700Parameterization of the coupling between strain and order parameter for LuF[SeO3]
http://scripts.iucr.org/cgi-bin/paper?ks5402
The high-temperature phase transition of LuF[SeO3] has been characterized by time-resolved high-resolution synchrotron powder diffraction. On heating, a second-order structural phase transition was found at 393 K, while on cooling the same phase transition occurs at 371 K, showing a large hysteresis typical for a first-order phase transition. Detailed analysis using sequential and parametric whole powder pattern fitting revealed that the coupling between the strain and the displacive order parameter determines the behaviour of the material during the phase transition. Different possible coupling mechanisms have been evaluated and the most probable rationalized.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Magdysyuk, O.V.Müller, M.Dinnebier, R.E.Lipp, C.Schleid, T.2014-03-28doi:10.1107/S1600576714002192International Union of CrystallographyThe high-temperature phase transition of LuF[SeO3] has been characterized by time-resolved high-resolution synchrotron powder diffraction, and the coupling between the strain and the displacive order parameter has been analysed by parametric refinement using different models.ENphase transitionssynchrotron powder diffractionstraindisplacive order parameterThe high-temperature phase transition of LuF[SeO3] has been characterized by time-resolved high-resolution synchrotron powder diffraction. On heating, a second-order structural phase transition was found at 393 K, while on cooling the same phase transition occurs at 371 K, showing a large hysteresis typical for a first-order phase transition. Detailed analysis using sequential and parametric whole powder pattern fitting revealed that the coupling between the strain and the displacive order parameter determines the behaviour of the material during the phase transition. Different possible coupling mechanisms have been evaluated and the most probable rationalized.text/htmlParameterization of the coupling between strain and order parameter for LuF[SeO3]text2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers701711An iterative method to extract the size distribution of non-interacting polydisperse spherical particles from small-angle scattering data
http://scripts.iucr.org/cgi-bin/paper?he5645
In this article, an iterative method for estimating the size distribution of non-interacting polydisperse spherical particles from small-angle scattering data is presented. It utilizes the iterative addition of relevant contributions to an instantaneous size distribution, as obtained from the fractional difference between the experimental data and the simulated profile. An inverse relation between scattering vector and real space is assumed. This method does not demand the consideration of any basis function set together with an imposed constraint such as a Lagrange multiplier, nor does it depend on the Titchmarsh transform. It is demonstrated that the method works quite well in extracting several forms of distribution. The robustness of the present method is examined through the successful retrieval of several forms of distribution, namely monomodal, bimodal, trimodal, triangular and bitriangular distributions. Finally, the method has also been employed to extract the particle size distribution from experimental small-angle X-ray scattering data obtained from colloidal dispersions of silica.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Sen, D.Das, A.Mazumder, S.2014-03-28doi:10.1107/S1600576714003835International Union of CrystallographyA new iterative method can extract the size distribution of non-interacting polydisperse spherical particles from a small-angle scattering profile. This method does not demand the consideration of any basis function or depend on any numerical transform.ENparticle size distributionsmall-angle scatteringiterative methodspolydisperse systemsIn this article, an iterative method for estimating the size distribution of non-interacting polydisperse spherical particles from small-angle scattering data is presented. It utilizes the iterative addition of relevant contributions to an instantaneous size distribution, as obtained from the fractional difference between the experimental data and the simulated profile. An inverse relation between scattering vector and real space is assumed. This method does not demand the consideration of any basis function set together with an imposed constraint such as a Lagrange multiplier, nor does it depend on the Titchmarsh transform. It is demonstrated that the method works quite well in extracting several forms of distribution. The robustness of the present method is examined through the successful retrieval of several forms of distribution, namely monomodal, bimodal, trimodal, triangular and bitriangular distributions. Finally, the method has also been employed to extract the particle size distribution from experimental small-angle X-ray scattering data obtained from colloidal dispersions of silica.text/htmlAn iterative method to extract the size distribution of non-interacting polydisperse spherical particles from small-angle scattering datatext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers712718Therapy modifies cystine kidney stones at the macroscopic scale. Do such alterations exist at the mesoscopic and nanometre scale?
http://scripts.iucr.org/cgi-bin/paper?ks5391
With an incidence of 1:7000 births, cystinuria, the most frequent cause of stone formation among genetic diseases, represents a major medical problem. Twenty-five cystine stones randomly selected from cystinuric patients were investigated. From a crystallographic point of view, cystine stones are composed of micrometre size crystallites, which are made up of an aggregation of nanocrystals. Through scanning electron microscopy, the morphology and size of the crystallites have been described, while the size of the nanocrystals was investigated by means of powder neutron diffraction. Powder neutron diffraction analysis and/or scanning electron microscopy examination of cystine stones provide evidence that usual alkalinization by sodium bicarbonate associated with high diuresis significantly reduces the size of both nanocrystals and crystallites, while for other treatments, including alkalinizing drugs and thiol derivatives, the data suggest mainly changes in the topology of crystallites. Alkalinization with sodium bicarbonate affects cystine kidney stones at the mesoscopic and nanoscopic scales, while other medical treatments only alter their surface. Such an approach may help to assess the interaction between drugs and cystine stones in cystinuric patients.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Bazin, D.Daudon, M.André, G.Weil, R.Véron, E.Matzen, G.2014-03-28doi:10.1107/S1600576714004658International Union of CrystallographyWith an incidence of 1:7000 births, cystinuria is the most frequent genetic disease inducing nephrolithiasis. It is shown that alkalinization with sodium bicarbonate affects cystine kidney stones at the mesoscopic and nanoscopic scales, while other medical treatments only alter their surface, a result which may help to assess the interaction between drugs and cystine stones in cystinuric patients.ENcystinuriacystine stonesscanning electron microscopypowder neutron diffractionalkalinizationthiol derivativesWith an incidence of 1:7000 births, cystinuria, the most frequent cause of stone formation among genetic diseases, represents a major medical problem. Twenty-five cystine stones randomly selected from cystinuric patients were investigated. From a crystallographic point of view, cystine stones are composed of micrometre size crystallites, which are made up of an aggregation of nanocrystals. Through scanning electron microscopy, the morphology and size of the crystallites have been described, while the size of the nanocrystals was investigated by means of powder neutron diffraction. Powder neutron diffraction analysis and/or scanning electron microscopy examination of cystine stones provide evidence that usual alkalinization by sodium bicarbonate associated with high diuresis significantly reduces the size of both nanocrystals and crystallites, while for other treatments, including alkalinizing drugs and thiol derivatives, the data suggest mainly changes in the topology of crystallites. Alkalinization with sodium bicarbonate affects cystine kidney stones at the mesoscopic and nanoscopic scales, while other medical treatments only alter their surface. Such an approach may help to assess the interaction between drugs and cystine stones in cystinuric patients.text/htmlTherapy modifies cystine kidney stones at the macroscopic scale. Do such alterations exist at the mesoscopic and nanometre scale?text2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers719725On identification of symmetric and improperly quasi-symmetric grain boundaries
http://scripts.iucr.org/cgi-bin/paper?rw5063
Symmetric and improperly quasi-symmetric grain boundaries have special geometric features. They are important reference boundaries in quantitative studies of boundary networks. Methods for identification of symmetric and improperly quasi-symmetric boundaries used so far, which are based on distance functions defined in the space of boundary parameters, are computationally complex and inefficient. In this article, new parameters that approximate the distances to the nearest symmetric and improperly quasi-symmetric boundaries are defined to simplify and speed up the analyses. Very strong correlations between the new parameters and the corresponding distances validate these new parameters to be a suitable replacement for the distances. Distributions of the introduced parameters may serve as characteristics of boundary networks. As an example, the new parameters are applied to the studies of symmetric and improperly quasi-symmetric characters of boundaries in three-dimensional microstructure data collected from a nickel-based superalloy.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Glowinski, K.2014-03-28doi:10.1107/S160057671400435XInternational Union of CrystallographyNew parameters approximating the accurate distances to the nearest symmetric and improperly quasi-symmetric boundaries are defined to speed up analyses of grain boundary networks. The new parameters are used for studies of symmetric and improperly quasi-symmetric boundaries in three-dimensional data of a nickel-based superalloy.ENgrain boundariessymmetric boundariesquasi-symmetric boundariesmacroscopic boundary parametersmicrostructureSymmetric and improperly quasi-symmetric grain boundaries have special geometric features. They are important reference boundaries in quantitative studies of boundary networks. Methods for identification of symmetric and improperly quasi-symmetric boundaries used so far, which are based on distance functions defined in the space of boundary parameters, are computationally complex and inefficient. In this article, new parameters that approximate the distances to the nearest symmetric and improperly quasi-symmetric boundaries are defined to simplify and speed up the analyses. Very strong correlations between the new parameters and the corresponding distances validate these new parameters to be a suitable replacement for the distances. Distributions of the introduced parameters may serve as characteristics of boundary networks. As an example, the new parameters are applied to the studies of symmetric and improperly quasi-symmetric characters of boundaries in three-dimensional microstructure data collected from a nickel-based superalloy.text/htmlOn identification of symmetric and improperly quasi-symmetric grain boundariestext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers726731Characterization of phase-transition-induced micro-domain structures in vanadium dioxide
http://scripts.iucr.org/cgi-bin/paper?ks5405
The displacive structural phase transition of vanadium dioxide (VO2) from the high-temperature tetragonal rutile (R) phase to the low-temperature monoclinic M1 or M2 phase may induce the formation of a variety of domain structures. Here, all possible types of phase-transition-induced domain structures of the M1 and M2 phases have been theoretically formulated by using a general space group method. The predicted domain structures of the M1 phase, including mirror or rotation twins and antiphase domains, have been confirmed by transmission electron microscopy observation of VO2 powders and films, while the antiphase domains have never been involved in previous studies. The changes undergone by domain structures during a thermal or electron-beam-induced phase transition have been investigated. These results may suggest the potential influence of domain structures on the nucleation and progress of phase transitions, which unambiguously affect the hysteresis behavior of the first-order transition of VO2.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Lu, P.Zhou, J.Liu, X.Zhang, Z.Xu, F.Zhang, L.Mou, X.Feng, J.Gao, Y.Zhao, J.2014-03-28doi:10.1107/S1600576714002854International Union of CrystallographyAll the possible kinds of phase-transition-induced domain structures in the insulating M1 and M2 phases of vanadium dioxide were theoretically predicted using a general space group method and characterized by transmission electron microscopy.ENphase transitionsdomain structuresvanadium dioxideThe displacive structural phase transition of vanadium dioxide (VO2) from the high-temperature tetragonal rutile (R) phase to the low-temperature monoclinic M1 or M2 phase may induce the formation of a variety of domain structures. Here, all possible types of phase-transition-induced domain structures of the M1 and M2 phases have been theoretically formulated by using a general space group method. The predicted domain structures of the M1 phase, including mirror or rotation twins and antiphase domains, have been confirmed by transmission electron microscopy observation of VO2 powders and films, while the antiphase domains have never been involved in previous studies. The changes undergone by domain structures during a thermal or electron-beam-induced phase transition have been investigated. These results may suggest the potential influence of domain structures on the nucleation and progress of phase transitions, which unambiguously affect the hysteresis behavior of the first-order transition of VO2.text/htmlCharacterization of phase-transition-induced micro-domain structures in vanadium dioxidetext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers732738High-temperature Raman spectroscopy of microstructure around the growing β-BaB2O4 crystal in the BaO–B2O3–Na2O system
http://scripts.iucr.org/cgi-bin/paper?ks5393
High-temperature Raman spectroscopy has been applied to study in situ the microstructure of the solution near the β-BaB2O4 crystal–solution interface in the BaO–B2O3–Na2O growth system. A boundary layer near the crystal–solution interface was observed. In accordance with the high-temperature Raman spectroscopy and first principles calculations, a boron–oxygen structural model is proposed to explain the microstructure of the solution and growth habit. The results show that the growth solution contains a special group, [BO2ØBOØB=O]3− (Ø = bridging oxygen), which transformed to the growth unit [B3O6]3− near the interface.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Liu, S.Zhang, G.Wan, S.Jiang, X.Wang, Y.Lin, Z.Wu, Y.2014-03-28doi:10.1107/S160057671400377XInternational Union of CrystallographyHigh-temperature Raman spectroscopy was applied to study the microstructure of the BaO–B2O3–Na2O solution for β-BaB2O4 crystal growth. The Raman spectrum of the growth solution was calculated, and the calculated result coincided well with the experimental result.ENhigh-temperature Raman spectroscopyβ-BaB2O4boundary layersmicrostructureHigh-temperature Raman spectroscopy has been applied to study in situ the microstructure of the solution near the β-BaB2O4 crystal–solution interface in the BaO–B2O3–Na2O growth system. A boundary layer near the crystal–solution interface was observed. In accordance with the high-temperature Raman spectroscopy and first principles calculations, a boron–oxygen structural model is proposed to explain the microstructure of the solution and growth habit. The results show that the growth solution contains a special group, [BO2ØBOØB=O]3− (Ø = bridging oxygen), which transformed to the growth unit [B3O6]3− near the interface.text/htmlHigh-temperature Raman spectroscopy of microstructure around the growing β-BaB2O4 crystal in the BaO–B2O3–Na2O systemtext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers739744Structure evolution with Sr content of the perovskite-like materials La2−xSrxCoTiO6 (0 ≤ x ≤ 0.5)
http://scripts.iucr.org/cgi-bin/paper?rw5065
The oxide series La2−xSrxCoTiO6 (0 ≤ x ≤ 1.0) belong to the perovskite family with general formula ABO3. The evolution of the room-temperature structure as a function of the Sr content was studied using complementary techniques by applying the symmetry-adapted modes formalism (AMPLIMODES). In the compositional range presented in this article (0 ≤ x ≤ 0.5), the compounds adopt distorted perovskite structures of monoclinic (space group P21/n) or orthorhombic (space group Pnma) symmetry, both with octahedral tilting scheme (a−a−c+) (out of phase along two perovskite main directions and in phase along the third direction). The main difference between these structures is the existence of rock-salt order of B ions in the monoclinic symmetry, which is lost for x ≥ 0.30. As the Sr content increases, a better matching of the A—O and B—O distances occurs. This is produced by an elongation of the A—O distance as La3+ is replaced by the larger ion Sr2+, and the shortening of the B—O distance due to the oxidation of Co2+ to Co3+ induced by the aliovalent substitution. As a result, the cuboctahedral A-site cavity becomes less and less distorted; the A ion tends to occupy its ideal positions, increasing its coordination and giving rise to a more symmetrical structure. In the whole compositional range, the symmetry-adapted atomic displacements (modes) responsible for the out-of-phase tilting of the BO6 octahedra remain active but those associated with the in-phase tilting become negligible, anticipating for x ≥ 0.6 a transition to a new structure with tilting scheme either (a0a0c−) (space group I4/mcm) or (a−a−a0) (space group Imma) or (a−a−a−) (space group R\overline 3c).Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Gómez-Pérez, A.Pérez-Flores, J.C.Ritter, C.Boulahya, K.Castro, G.R.García-Alvarado, F.Amador, U.2014-03-28doi:10.1107/S1600576714004907International Union of CrystallographySubstitution in the perovskite A site releases internal structural stress as a result of a better matching of the A—O and B—O distances, leading to less distorted phases (transition from monoclinic to orthorhombic). Symmetry-adapted mode decomposition revealed that the out-of-phase tilt of BO6 octahedra slightly varies with Sr content, whereas the in-phase tilt strongly decreases to almost vanish for x > 0.5, anticipating a transition to a more symmetric structure.ENperovskitesphase transitionsneutron diffractionsynchrotron X-ray diffractionAMPLIMODEScobaltiteThe oxide series La2−xSrxCoTiO6 (0 ≤ x ≤ 1.0) belong to the perovskite family with general formula ABO3. The evolution of the room-temperature structure as a function of the Sr content was studied using complementary techniques by applying the symmetry-adapted modes formalism (AMPLIMODES). In the compositional range presented in this article (0 ≤ x ≤ 0.5), the compounds adopt distorted perovskite structures of monoclinic (space group P21/n) or orthorhombic (space group Pnma) symmetry, both with octahedral tilting scheme (a−a−c+) (out of phase along two perovskite main directions and in phase along the third direction). The main difference between these structures is the existence of rock-salt order of B ions in the monoclinic symmetry, which is lost for x ≥ 0.30. As the Sr content increases, a better matching of the A—O and B—O distances occurs. This is produced by an elongation of the A—O distance as La3+ is replaced by the larger ion Sr2+, and the shortening of the B—O distance due to the oxidation of Co2+ to Co3+ induced by the aliovalent substitution. As a result, the cuboctahedral A-site cavity becomes less and less distorted; the A ion tends to occupy its ideal positions, increasing its coordination and giving rise to a more symmetrical structure. In the whole compositional range, the symmetry-adapted atomic displacements (modes) responsible for the out-of-phase tilting of the BO6 octahedra remain active but those associated with the in-phase tilting become negligible, anticipating for x ≥ 0.6 a transition to a new structure with tilting scheme either (a0a0c−) (space group I4/mcm) or (a−a−a0) (space group Imma) or (a−a−a−) (space group R\overline 3c).text/htmlStructure evolution with Sr content of the perovskite-like materials La2−xSrxCoTiO6 (0 ≤ x ≤ 0.5)text2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers745754989515989516989517989518989519989520989521989522989523989524Hierarchical O(N) computation of small-angle scattering profiles and their associated derivatives
http://scripts.iucr.org/cgi-bin/paper?nb5097
The need for fast approximate algorithms for Debye summation arises in computations performed in crystallography, small/wide-angle X-ray scattering and small-angle neutron scattering. When integrated into structure refinement protocols these algorithms can provide significant speed up over direct all-atom-to-all-atom computation. However, these protocols often employ an iterative gradient-based optimization procedure, which then requires derivatives of the profile with respect to atomic coordinates. This article presents an accurate, O(N) cost algorithm for the computation of scattering profile derivatives. The results reported here show orders of magnitude improvement in computational efficiency, while maintaining the prescribed accuracy. This opens the possibility to efficiently integrate small-angle scattering data into the structure determination and refinement of macromolecular systems.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Berlin, K.Gumerov, N.A.Fushman, D.Duraiswami, R.2014-03-28doi:10.1107/S1600576714004671International Union of CrystallographyStructure refinement protocols based on small-angle X-ray scattering iteratively adjust the posited positions of atoms in a structure via a gradient-based constrained optimization to ensure that experimental scattering profile data are matched. This requires computation of the profile and its gradient with respect to atomic coordinates at every step. The fast algorithms proposed in this article reduce these to a cost that is linear in the number of atoms for any specified accuracy.ENsmall-angle scatteringwide-angle scatteringJacobiangradientsThe need for fast approximate algorithms for Debye summation arises in computations performed in crystallography, small/wide-angle X-ray scattering and small-angle neutron scattering. When integrated into structure refinement protocols these algorithms can provide significant speed up over direct all-atom-to-all-atom computation. However, these protocols often employ an iterative gradient-based optimization procedure, which then requires derivatives of the profile with respect to atomic coordinates. This article presents an accurate, O(N) cost algorithm for the computation of scattering profile derivatives. The results reported here show orders of magnitude improvement in computational efficiency, while maintaining the prescribed accuracy. This opens the possibility to efficiently integrate small-angle scattering data into the structure determination and refinement of macromolecular systems.text/htmlHierarchical O(N) computation of small-angle scattering profiles and their associated derivativestext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers755761Imaging of strain and lattice orientation by quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping
http://scripts.iucr.org/cgi-bin/paper?rg5061
Numerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X-ray diffraction microscopy has become a routine technique, giving access to structural properties with sub-micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline (ESRF, Grenoble). A structural scanning probe microscope with intriguing imaging qualities is obtained. The technique consists in a two-dimensional quick continuous mapping with sub-micrometre resolution of a sample at a given reciprocal space position. These real space maps are made by continuously moving the sample while recording scattering images with a fast two-dimensional detector for every point along a rocking curve. Five-dimensional data sets are then produced, consisting of millions of detector images. The images are processed by the user-friendly X-ray strain orientation calculation software (XSOCS), which has been developed at ID01 for automatic analysis. It separates tilt and strain and generates two-dimensional maps of these parameters. At spatial resolutions of typically 200–800 nm, this quick imaging technique achieves strain sensitivity below Δa/a = 10−5 and a resolution of tilt variations down to 10−3° over a field of view of 100 × 100 µm.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Chahine, G.A.Richard, M.-I.Homs-Regojo, R.A.Tran-Caliste, T.N.Carbone, D.Jacques, V.L.R.Grifone, R.Boesecke, P.Katzer, J.Costina, I.Djazouli, H.Schroeder, T.Schülli, T.U.2014-03-28doi:10.1107/S1600576714004506International Union of CrystallographyA new quick continuous mapping technique that comes together with a software package (XSOCS) for automatic data analysis for strain and lattice orientation is presented as a novel type of scanning probe microscope.ENreciprocal space mappingstrainlattice orientationdata analysis softwarescanning X-ray diffraction microscopyscanning probe microscopyNumerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X-ray diffraction microscopy has become a routine technique, giving access to structural properties with sub-micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline (ESRF, Grenoble). A structural scanning probe microscope with intriguing imaging qualities is obtained. The technique consists in a two-dimensional quick continuous mapping with sub-micrometre resolution of a sample at a given reciprocal space position. These real space maps are made by continuously moving the sample while recording scattering images with a fast two-dimensional detector for every point along a rocking curve. Five-dimensional data sets are then produced, consisting of millions of detector images. The images are processed by the user-friendly X-ray strain orientation calculation software (XSOCS), which has been developed at ID01 for automatic analysis. It separates tilt and strain and generates two-dimensional maps of these parameters. At spatial resolutions of typically 200–800 nm, this quick imaging technique achieves strain sensitivity below Δa/a = 10−5 and a resolution of tilt variations down to 10−3° over a field of view of 100 × 100 µm.text/htmlImaging of strain and lattice orientation by quick scanning X-ray microscopy combined with three-dimensional reciprocal space mappingtext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers762769Crystallographic study of grain refinement of Al by Nb addition
http://scripts.iucr.org/cgi-bin/paper?ks5416
The grain refinement of Al by the addition of a small amount of peritectic-forming solute, Nb, has been studied from the crystallographic point of view. Combining the observations of optical microscopy and scanning electron microscopy with the results of energy-dispersive X-ray spectroscopy and X-ray diffraction, it is confirmed that the particles observed at or near the grain centres of refined Al alloys are pro-peritectic Al3Nb particles. The crystallographic matching between the Al3Nb particles and Al grains has also been evaluated using an edge-to-edge matching model and further verified using electron backscatter diffraction and transmission electron microscopy. It is found that there are reproducible crystallographic orientation relationships between the Al3Nb particles and Al grains, and the experimental results are consistent with the predictions of the edge-to-edge matching model. This implies that the pro-peritectic Al3Nb particles are favourable nucleation sites for Al grains from the crystallographic point of view. Furthermore, the analysis of the size distribution of Al3Nb particles reveals that the Al3Nb particles at the grain centres have relatively large particle size, which also corroborates the high potency of Al3Nb according to the free growth model. It is therefore concluded that the significant grain refinement resulting from the addition of Nb is predominantly attributed to the in situ formed Al3Nb particles which promote grain refinement via enhanced heterogeneous nucleation.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Wang, F.Qiu, D.Liu, Z.-L.Taylor, J.A.Easton, M.A.Zhang, M.-X.2014-03-28doi:10.1107/S1600576714004476International Union of CrystallographyUsing the edge-to-edge matching model, electron backscatter diffraction and transmission electron microscopy, good crystallographic matching and reproducible orientation relationships have been identified between refined Al grains and in situ formed pro-peritectic Al3Nb particles. These particles are therefore suggested to account for the considerable grain refinement in the Al alloys with addition of Nb solute.ENAl alloysgrain refinementperitecticcrystallographyThe grain refinement of Al by the addition of a small amount of peritectic-forming solute, Nb, has been studied from the crystallographic point of view. Combining the observations of optical microscopy and scanning electron microscopy with the results of energy-dispersive X-ray spectroscopy and X-ray diffraction, it is confirmed that the particles observed at or near the grain centres of refined Al alloys are pro-peritectic Al3Nb particles. The crystallographic matching between the Al3Nb particles and Al grains has also been evaluated using an edge-to-edge matching model and further verified using electron backscatter diffraction and transmission electron microscopy. It is found that there are reproducible crystallographic orientation relationships between the Al3Nb particles and Al grains, and the experimental results are consistent with the predictions of the edge-to-edge matching model. This implies that the pro-peritectic Al3Nb particles are favourable nucleation sites for Al grains from the crystallographic point of view. Furthermore, the analysis of the size distribution of Al3Nb particles reveals that the Al3Nb particles at the grain centres have relatively large particle size, which also corroborates the high potency of Al3Nb according to the free growth model. It is therefore concluded that the significant grain refinement resulting from the addition of Nb is predominantly attributed to the in situ formed Al3Nb particles which promote grain refinement via enhanced heterogeneous nucleation.text/htmlCrystallographic study of grain refinement of Al by Nb additiontext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers770779Phase-sensitive small-angle neutron scattering
http://scripts.iucr.org/cgi-bin/paper?to5061
A method is described for determining the neutron scattering length density distribution of a molecular-scale object directly from phase-sensitive small-angle neutron scattering (SANS). The structure factor amplitude is obtained through the use of a reference structure for a collection of randomly oriented, identical objects in the dilute solution limit (negligible interparticle correlations). This work extends some of the techniques developed in recent years for phase-sensitive specular neutron reflectometry to SANS, although the approach presented here is applicable only within the range of validity of the Born approximation. The scattering object is treated as a composite consisting of an `unknown' part of interest plus a reference component, the real-space structure of the latter being completely known. If, for example, the reference part of the object is composed of a ferromagnetic material (the magnetization of which is saturated), then polarized neutron beams can be employed to extract the information required for an unambiguous inversion of the scattering data without chemical substitution. The angular averaging over all possible relative orientations of the composite object does not result in a cancellation of the phase information since the reference and unknown parts of each object have a fixed spatial relationship. The new approach proposed here is not simply another type of isomorphic substitution, but also involves a reformulation of the underlying mathematical analysis of this particular scattering problem.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Majkrzak, C.F.Krycka, K.Krueger, S.Berk, N.F.Kienzle, P.Maranville, B.2014-03-28doi:10.1107/S1600576714004956International Union of CrystallographyA method is proposed for determining the scattering length density distribution of a molecular-scale object directly from phase-sensitive small-angle neutron scattering. The structure factor amplitude is obtained through the use of a reference structure for a collection of randomly oriented, identical objects in the dilute solution limit.ENneutron scattering length densitysmall-angle neutron scatteringA method is described for determining the neutron scattering length density distribution of a molecular-scale object directly from phase-sensitive small-angle neutron scattering (SANS). The structure factor amplitude is obtained through the use of a reference structure for a collection of randomly oriented, identical objects in the dilute solution limit (negligible interparticle correlations). This work extends some of the techniques developed in recent years for phase-sensitive specular neutron reflectometry to SANS, although the approach presented here is applicable only within the range of validity of the Born approximation. The scattering object is treated as a composite consisting of an `unknown' part of interest plus a reference component, the real-space structure of the latter being completely known. If, for example, the reference part of the object is composed of a ferromagnetic material (the magnetization of which is saturated), then polarized neutron beams can be employed to extract the information required for an unambiguous inversion of the scattering data without chemical substitution. The angular averaging over all possible relative orientations of the composite object does not result in a cancellation of the phase information since the reference and unknown parts of each object have a fixed spatial relationship. The new approach proposed here is not simply another type of isomorphic substitution, but also involves a reformulation of the underlying mathematical analysis of this particular scattering problem.text/htmlPhase-sensitive small-angle neutron scatteringtext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers780787Characterization of TEMPO-oxidized cellulose nanofibers in aqueous suspension by small-angle X-ray scattering
http://scripts.iucr.org/cgi-bin/paper?fs5073
Cellulose nanofibers, extracted from wood pulps using the (2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO)-mediated oxidation method, are low-cost, sustainable and high-performance materials with potential usage in many applications. The structural information of these cellulose nanofibers in aqueous suspension was characterized by synchrotron small-angle X-ray scattering (SAXS). A simplified ribbon model having a near rectangular cross section was found to give the best fit to the SAXS results. The analytical expression of the ribbon model also led to a higher calculation efficiency compared with the more conventional parallelepiped model. The extracted structural information included the cross-section size and size distribution of the cellulose nanofibers. For example, for nanofibers prepared from the dried pulp of the maritime pine, the size-weighted averages of thickness and width were 3.2 and 12.7 nm, respectively, and the corresponding standard deviations were 2.2 and 5.5 nm, respectively. The scattering results of the size-weighted average of the nanofiber width are also consistent with those determined directly from transmission electron microscopy.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Su, Y.Burger, C.Hsiao, B.S.Chu, B.2014-03-28doi:10.1107/S1600576714005020International Union of CrystallographyThe morphology, dimensions and polydispersity of cellulose nanofibers, extracted from wood pulps using the (2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO)-mediated oxidation method, were characterized by the solution small-angle X-ray scattering technique. A simplified ribbon model was derived to fit the scattering profile with high quality and computational efficiency, and the fitting results were consistent with transmission electron microscopy data.ENcellulose nanofiberTEMPO-mediated oxidationsmall-angle X-ray scatteringribbon modeltransmission electron microscopyCellulose nanofibers, extracted from wood pulps using the (2,2,6,6-tetramethylpiperidine-1-yl)oxyl (TEMPO)-mediated oxidation method, are low-cost, sustainable and high-performance materials with potential usage in many applications. The structural information of these cellulose nanofibers in aqueous suspension was characterized by synchrotron small-angle X-ray scattering (SAXS). A simplified ribbon model having a near rectangular cross section was found to give the best fit to the SAXS results. The analytical expression of the ribbon model also led to a higher calculation efficiency compared with the more conventional parallelepiped model. The extracted structural information included the cross-section size and size distribution of the cellulose nanofibers. For example, for nanofibers prepared from the dried pulp of the maritime pine, the size-weighted averages of thickness and width were 3.2 and 12.7 nm, respectively, and the corresponding standard deviations were 2.2 and 5.5 nm, respectively. The scattering results of the size-weighted average of the nanofiber width are also consistent with those determined directly from transmission electron microscopy.text/htmlCharacterization of TEMPO-oxidized cellulose nanofibers in aqueous suspension by small-angle X-ray scatteringtext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyresearch papers788798High-efficiency focusing of hard X-rays exploiting the quasi-mosaic effect in a bent germanium crystal
http://scripts.iucr.org/cgi-bin/paper?ks5404
A germanium crystal was bent through a grid of superficial grooves, manufactured on the sample surface. The resulting diffraction planes were bent thanks to quasi-mosaicity, which is an effect of mechanical anisotropy in crystals. High integrated diffraction efficiency was achieved in symmetric Laue geometry with a monochromatic X-ray beam set at 150 and 300 keV. It is demonstrated that the sample is capable of efficiently focusing X-rays. Such crystals can be used as optical components to focalize X- and γ-rays in a high-resolution Laue lens.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Camattari, R.Paternò, G.Battelli, A.Bellucci, V.Bastie, P.Guidi, V.2014-03-28doi:10.1107/S1600576714005056International Union of CrystallographyA germanium crystal has been bent through a grid of superficial grooves manufactured on the sample surface. High diffraction efficiency was achieved for a monochromatic X-ray beam at 150 and 300 keV and focusing capability has been demonstrated.ENA germanium crystal was bent through a grid of superficial grooves, manufactured on the sample surface. The resulting diffraction planes were bent thanks to quasi-mosaicity, which is an effect of mechanical anisotropy in crystals. High integrated diffraction efficiency was achieved in symmetric Laue geometry with a monochromatic X-ray beam set at 150 and 300 keV. It is demonstrated that the sample is capable of efficiently focusing X-rays. Such crystals can be used as optical components to focalize X- and γ-rays in a high-resolution Laue lens.text/htmlHigh-efficiency focusing of hard X-rays exploiting the quasi-mosaic effect in a bent germanium crystaltext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographyshort communications799802WinCSD: software package for crystallographic calculations (Version 4)
http://scripts.iucr.org/cgi-bin/paper?to5068
The fourth version of the program package WinCSD is multi-purpose computer software for crystallographic calculations using single-crystal and powder X-ray and neutron diffraction data. The software environment and the graphical user interface are built using the platform of the Microsoft .NET Framework, which grants independence from changing Windows operating systems and allows for transferring to other operating systems. Graphic applications use the three-dimensional OpenGL graphics language. WinCSD covers the complete spectrum of crystallographic calculations, including powder diffraction pattern deconvolution, crystal structure solution and refinement in 3 + d space, refinement of the multipole model and electron density studies from diffraction data, and graphical representation of crystallographic information.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Akselrud, L.Grin, Y.2014-03-11doi:10.1107/S1600576714001058International Union of CrystallographyThe fourth version of the program package WinCSD is multi-purpose computer software for crystallographic calculations using single-crystal and powder X-ray and neutron diffraction data. WinCSD covers the complete spectrum of crystallographic calculations, including powder diffraction pattern deconvolution, crystal structure solution and refinement in 3 + d space, reconstruction of electron density from diffraction data, and graphical representation of crystallographic information.ENcrystallographic calculationscomputer programscrystal structure solutionrefinementThe fourth version of the program package WinCSD is multi-purpose computer software for crystallographic calculations using single-crystal and powder X-ray and neutron diffraction data. The software environment and the graphical user interface are built using the platform of the Microsoft .NET Framework, which grants independence from changing Windows operating systems and allows for transferring to other operating systems. Graphic applications use the three-dimensional OpenGL graphics language. WinCSD covers the complete spectrum of crystallographic calculations, including powder diffraction pattern deconvolution, crystal structure solution and refinement in 3 + d space, refinement of the multipole model and electron density studies from diffraction data, and graphical representation of crystallographic information.text/htmlWinCSD: software package for crystallographic calculations (Version 4)text2472014-03-11Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographycomputer programs803805An idealized molecular geometry library for refinement of poorly behaved molecular fragments with constraints
http://scripts.iucr.org/cgi-bin/paper?kk5167
An idealized molecular geometry library with 40 geometries of molecules and ions optimized by density functional theory methods has been created. All geometries are accessible through a web site. The library entries are tailored for constrained (also known as rigid body) refinements of problematic small-molecule structures with the OLEX2 and SHELXL software packages. The library application is demonstrated with the refinement of a Pd complex, trans-Pd(dimethyl sulfoxide)(OH2)(trifluoroacetate)2, that co-crystallizes in a 2:1 ratio with a solvent molecule of ethyl acetate disordered over an inversion center. Alternative approaches to constrained refinements are discussed.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Guzei, I.A.2014-03-28doi:10.1107/S1600576714004427International Union of CrystallographyAn idealized molecular geometry library has been created as a web site to be used for refinement of difficult structures with constrained fragment geometries. The library application is illustrated with a practical example.ENidealized molecular geometrydensity functional theoryAn idealized molecular geometry library with 40 geometries of molecules and ions optimized by density functional theory methods has been created. All geometries are accessible through a web site. The library entries are tailored for constrained (also known as rigid body) refinements of problematic small-molecule structures with the OLEX2 and SHELXL software packages. The library application is demonstrated with the refinement of a Pd complex, trans-Pd(dimethyl sulfoxide)(OH2)(trifluoroacetate)2, that co-crystallizes in a 2:1 ratio with a solvent molecule of ethyl acetate disordered over an inversion center. Alternative approaches to constrained refinements are discussed.text/htmlAn idealized molecular geometry library for refinement of poorly behaved molecular fragments with constraintstext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographycomputer programs806809Two practical Java software tools for small-angle X-ray scattering analysis of biomolecules
http://scripts.iucr.org/cgi-bin/paper?he5640
Small-angle X-ray scattering has established itself as a common technique in structural biology research. Here, two novel Java applications to aid modelling of three-dimensional macromolecular structures based on small-angle scattering data are described. MolScat is an application that computes small-angle scattering intensities from user-provided three-dimensional models. The program can fit the theoretical scattering intensities to experimental X-ray scattering data. SAFIR is a program for interactive rigid-body modelling into low-resolution shapes restored from small-angle scattering data. The program has been designed with an emphasis on ease of use and intuitive handling. An embedded version of MolScat is used to enable quick evaluation of the fit between the model and experimental scattering data. SAFIR also provides options to refine macromolecular complexes with optional user-specified restraints against scattering data by means of a Monte Carlo approach.Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Hofmann, A.Whitten, A.E.2014-03-28doi:10.1107/S1600576714004737International Union of CrystallographyMolScat is an application that computes small-angle scattering intensities from user-provided three-dimensional models. The program can fit the theoretical scattering intensities to experimental X-ray scattering data. SAFIR is a program for interactive rigid-body modelling into low-resolution shapes restored from small-angle scattering data.ENmolecular modellingrigid-body fittingsmall-angle X-ray scatteringsoftwareSmall-angle X-ray scattering has established itself as a common technique in structural biology research. Here, two novel Java applications to aid modelling of three-dimensional macromolecular structures based on small-angle scattering data are described. MolScat is an application that computes small-angle scattering intensities from user-provided three-dimensional models. The program can fit the theoretical scattering intensities to experimental X-ray scattering data. SAFIR is a program for interactive rigid-body modelling into low-resolution shapes restored from small-angle scattering data. The program has been designed with an emphasis on ease of use and intuitive handling. An embedded version of MolScat is used to enable quick evaluation of the fit between the model and experimental scattering data. SAFIR also provides options to refine macromolecular complexes with optional user-specified restraints against scattering data by means of a Monte Carlo approach.text/htmlTwo practical Java software tools for small-angle X-ray scattering analysis of biomoleculestext2472014-03-28Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographycomputer programs810815Electron Crystallography. Electron Microscopy and Electron Diffraction. By Xiaodong Zou, Sven Hovmöller and Peter Oleynikov. Oxford University Press, 2011. Price (hardcover) GBP 52.50. ISBN-13: 978-0-19-958020-0.
http://scripts.iucr.org/cgi-bin/paper?pf0115
Copyright (c) 2014 International Union of Crystallographyurn:issn:1600-5767Hadermann, J.2014-02-22doi:10.1107/S1600576714002726International Union of CrystallographyENbook reviewtext/htmlElectron Crystallography. Electron Microscopy and Electron Diffraction. By Xiaodong Zou, Sven Hovmöller and Peter Oleynikov. Oxford University Press, 2011. Price (hardcover) GBP 52.50. ISBN-13: 978-0-19-958020-0.text2472014-02-22Copyright (c) 2014 International Union of CrystallographyJournal of Applied Crystallographybook reviews816818