Journal of Applied Crystallography
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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) 2019 International Union of Crystallography2019-01-10International 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 52, Part 1, 2019textweekly62002-02-01T00:00+00:001522019-01-10Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallography1urn:issn:1600-5767med@iucr.orgJanuary 20192019-01-10Journal of Applied Crystallographyhttp://journals.iucr.org/logos/rss10j.gif
//journals.iucr.org/j/issues/2019/01/00/isscontsbdy.html
Still imageQuantitative phase analysis of amorphous components in mixtures by using the direct-derivation method
http://scripts.iucr.org/cgi-bin/paper?to5185
The direct-derivation (DD) method is a new technique for quantitative phase analysis (QPA) [Toraya (2016). J. Appl. Cryst. 49, 1508–1516]. A simple equation, called the intensity–composition (IC) formula, is used to derive weight fractions of individual components (wk; k = 1–K) in a mixture. Two kinds of parameters are required as input data of the formula. One is the parameter Sk, which is the sum of observed powder diffraction intensities for each component, measured in a wide 2θ range and corrected for the Lorentz–polarization factor. The other is the parameter ak−1, defined by ak−1 = Mk−1∑nik2, where Mk is the chemical formula weight and nik is the number of electrons belonging to the ith atom in the chemical formula unit. The parameter ak−1 was originally derived by using the relationship between the peak height and the integrated value of the peak at the origin of the Patterson function, implicitly assuming the presence of periodic structures like crystals. In this study, the formula has been derived theoretically from a general assemblage of atoms resembling amorphous material, and the same expression as the original formula has been obtained. The physical meaning of ak−1, which represents `the total scattering power per chemical formula weight', has been reconfirmed in the present formulation. The IC formula has been tested experimentally by using two-, three- and four-component mixtures containing SiO2 or GeO2 glass powder. In the whole-powder-pattern fitting (WPPF) procedure, incorporated into the DD method, a background-subtracted halo pattern is directly fitted as one of the components in the mixture, together with profile models for crystalline components. In the WPPF, an interaction was observed between the parameters of the background function (BGF) and the parameter for scaling the halo pattern, and this resulted in systematic deviations of wk from weighed values. The deviations were ≤0.7% in the case of binary mixtures when the BGF was fixed at the correct background height, supporting the hypothesis that the DD method is applicable to the QPA of amorphous components.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Toraya, H.Omote, K.2019-02-01doi:10.1107/S1600576718016394International Union of CrystallographyThe direct-derivation method has been applied to the quantitative phase analysis of mixtures containing amorphous components. A theoretical basis has been given to the formula for deriving individual weight fractions from observed intensity data. The formula has been experimentally tested by whole-powder-pattern fitting to the observed patterns of mixtures containing amorphous components.ENX-ray powder diffractionquantitative phase analysisamorphous componentsdirect-derivation methodintensity–composition formulawhole-powder-pattern fittingThe direct-derivation (DD) method is a new technique for quantitative phase analysis (QPA) [Toraya (2016). J. Appl. Cryst. 49, 1508–1516]. A simple equation, called the intensity–composition (IC) formula, is used to derive weight fractions of individual components (wk; k = 1–K) in a mixture. Two kinds of parameters are required as input data of the formula. One is the parameter Sk, which is the sum of observed powder diffraction intensities for each component, measured in a wide 2θ range and corrected for the Lorentz–polarization factor. The other is the parameter ak−1, defined by ak−1 = Mk−1∑nik2, where Mk is the chemical formula weight and nik is the number of electrons belonging to the ith atom in the chemical formula unit. The parameter ak−1 was originally derived by using the relationship between the peak height and the integrated value of the peak at the origin of the Patterson function, implicitly assuming the presence of periodic structures like crystals. In this study, the formula has been derived theoretically from a general assemblage of atoms resembling amorphous material, and the same expression as the original formula has been obtained. The physical meaning of ak−1, which represents `the total scattering power per chemical formula weight', has been reconfirmed in the present formulation. The IC formula has been tested experimentally by using two-, three- and four-component mixtures containing SiO2 or GeO2 glass powder. In the whole-powder-pattern fitting (WPPF) procedure, incorporated into the DD method, a background-subtracted halo pattern is directly fitted as one of the components in the mixture, together with profile models for crystalline components. In the WPPF, an interaction was observed between the parameters of the background function (BGF) and the parameter for scaling the halo pattern, and this resulted in systematic deviations of wk from weighed values. The deviations were ≤0.7% in the case of binary mixtures when the BGF was fixed at the correct background height, supporting the hypothesis that the DD method is applicable to the QPA of amorphous components.text/htmlQuantitative phase analysis of amorphous components in mixtures by using the direct-derivation methodtext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers00Polar and non-polar structures of NH4TiOF3
http://scripts.iucr.org/cgi-bin/paper?pd5107
Ammonium oxofluorotitanate, NH4TiOF3, is probably the best known precursor for the synthesis of anatase mesocrystals. Transformation of NH4TiOF3 into TiO2 through thermal decomposition, accompanied by hydrolysis, preserves some structural features of the precursor. Currently, any discussion of the mechanism of this transformation is difficult, as the exact crystal structure of the starting compound is not available and no intermediate structures are known. This article describes the outcome of single-crystal and powder X-ray diffraction studies, revealing the existence of two polymorphs of the parent NH4TiOF3 at different temperatures. A second-order phase transition from the polar Pca21 α phase (1), stable at room temperature, to the Pma2 β phase (2) above ∼433 K has been demonstrated. The direction of the pseudo-fourfold axis in NH4TiOF3 coincides with the orientation of the fourfold axis of anatase mesocrystals, consistent with a topotactical transformation.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Boytsova, O.Dovgaliuk, I.Chernyshov, D.Eliseev, A.O'Brien, P.Sutherland, A.J.Bosak, A.2019-02-01doi:10.1107/S1600576718016606International Union of CrystallographyThe unambiguous determination of the crystal structure of two NH4TiOF3 polymorphs is provided. NH4TiOF3 is subject to a second-order phase transition from Pca21 to Pma2 on heating at around ∼453 K.ENNH4TiOF3second-order phase transitioncrystal and powder X-ray diffractionAmmonium oxofluorotitanate, NH4TiOF3, is probably the best known precursor for the synthesis of anatase mesocrystals. Transformation of NH4TiOF3 into TiO2 through thermal decomposition, accompanied by hydrolysis, preserves some structural features of the precursor. Currently, any discussion of the mechanism of this transformation is difficult, as the exact crystal structure of the starting compound is not available and no intermediate structures are known. This article describes the outcome of single-crystal and powder X-ray diffraction studies, revealing the existence of two polymorphs of the parent NH4TiOF3 at different temperatures. A second-order phase transition from the polar Pca21 α phase (1), stable at room temperature, to the Pma2 β phase (2) above ∼433 K has been demonstrated. The direction of the pseudo-fourfold axis in NH4TiOF3 coincides with the orientation of the fourfold axis of anatase mesocrystals, consistent with a topotactical transformation.text/htmlPolar and non-polar structures of NH4TiOF3text1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers0018805141880515Scattering functions of carved-ellipsoid-shaped particles
http://scripts.iucr.org/cgi-bin/paper?aj5311
Motivated by the enriched topologies from the newly discovered nano-scaled molecular clusters, custom carved-ellipsoid models are built and their scattering functions are explored. The scattering functions of these models are derived in ellipsoidal coordinates. The theoretical scattering curves of these models can be further obtained through numerical calculation. These models have been successfully applied to the fitting of experimental scattering curves of some so-called wheel-shaped metal oxide molecular clusters.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Li, M.Yin, P.2019-02-01doi:10.1107/S1600576718016771International Union of CrystallographyCarved-ellipsoid models are built and their scattering functions are explored. These models are applied successfully to the scattering curves of newly developed nano-scaled molecular clusters.ENcarved ellipsoidssmall-angle scatteringmolecular clusterspolyoxometalatesMotivated by the enriched topologies from the newly discovered nano-scaled molecular clusters, custom carved-ellipsoid models are built and their scattering functions are explored. The scattering functions of these models are derived in ellipsoidal coordinates. The theoretical scattering curves of these models can be further obtained through numerical calculation. These models have been successfully applied to the fitting of experimental scattering curves of some so-called wheel-shaped metal oxide molecular clusters.text/htmlScattering functions of carved-ellipsoid-shaped particlestext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers00Microstrain-assisted polymorphic phase transitions in (Eu1−xLax)2O3
http://scripts.iucr.org/cgi-bin/paper?ks5611
Solid solutions, (Eu1−xLax)2O3 (0 ≤ x ≤ 1), of the rare earth sesquioxides Eu2O3 and La2O3 have been prepared by a simple soft chemistry approach. The composition and morphology of the as-synthesized oxides have been characterized using energy-dispersive spectroscopy and scanning electron microscopy. The particles are of irregular shape and submicrometre size. In order to understand the structural evolution as a function of composition, angle-dispersive X-ray diffraction measurements have been carried out and the structural parameters have been obtained through Rietveld refinement. A structural phase transition from the cubic (C-type) to the monoclinic (B-type) structure and subsequently to the hexagonal (A-type) structure was observed with an increasing substitution of La. A detailed analysis of the transition boundaries in terms of the average cationic radius, RRE, shows that the onset of the C → B transition is at RRE = 0.980 Å, whereas the B → A transition occurs at RRE = 1.025 Å. A biphasic region of cubic and monoclinic structures is observed for 0.2 ≤ x ≤ 0.4 and one of monoclinic and hexagonal structures is observed for 0.5 ≤ x ≤ 0.6. The microstrain induced by the difference in size of the rare earth cations introduces a substitutional disorder in the crystal structure, which is a plausible cause of the observed phase transitions in these oxides.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Irshad, K.A.Saikumaran, A.Srihari, V.Kalavathi, S.Chandra Shekar, N.V.2019-02-01doi:10.1107/S1600576718016989International Union of CrystallographyA structural phase transition from a cubic to a monoclinic structure and subsequently to a hexagonal structure is observed with increasing cation size in the rare earth sesquioxide (Eu1−xLax)2O3. The microstrain and substitutional disorder in the crystal structure are considered to be the causes of the observed phase transition.ENrare earth sesquioxidesX-ray diffractionRietveld refinementpolymorphic phase transitionsSolid solutions, (Eu1−xLax)2O3 (0 ≤ x ≤ 1), of the rare earth sesquioxides Eu2O3 and La2O3 have been prepared by a simple soft chemistry approach. The composition and morphology of the as-synthesized oxides have been characterized using energy-dispersive spectroscopy and scanning electron microscopy. The particles are of irregular shape and submicrometre size. In order to understand the structural evolution as a function of composition, angle-dispersive X-ray diffraction measurements have been carried out and the structural parameters have been obtained through Rietveld refinement. A structural phase transition from the cubic (C-type) to the monoclinic (B-type) structure and subsequently to the hexagonal (A-type) structure was observed with an increasing substitution of La. A detailed analysis of the transition boundaries in terms of the average cationic radius, RRE, shows that the onset of the C → B transition is at RRE = 0.980 Å, whereas the B → A transition occurs at RRE = 1.025 Å. A biphasic region of cubic and monoclinic structures is observed for 0.2 ≤ x ≤ 0.4 and one of monoclinic and hexagonal structures is observed for 0.5 ≤ x ≤ 0.6. The microstrain induced by the difference in size of the rare earth cations introduces a substitutional disorder in the crystal structure, which is a plausible cause of the observed phase transitions in these oxides.text/htmlMicrostrain-assisted polymorphic phase transitions in (Eu1−xLax)2O3text1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers00Precision lattice parameter determination from transmission diffraction of thick specimens with irregular cross sections
http://scripts.iucr.org/cgi-bin/paper?kc5086
Accurate determination of lattice parameters from X-ray diffraction requires that the diffraction angles be measured very precisely, and significant errors result if the sample–detector separation differs from that assumed. Transmission diffraction from bones, which have a complex cross section and must be left intact, is a situation where this separation is difficult to measure and it may differ from position to position across the specimen. This article describes a method for eliminating the effect of variable sample cross section. Diffraction patterns for each position on the specimen are collected before and after 180° rotation about an axis normal to the cross section of interest. This places the centroid of the diffracting mass at the center of rotation and provides the absolute lattice parameters from the average apparent lattice parameters at the two rotation angles. Diffraction patterns were collected across the cross section of three specimens: a 3D-printed elliptical cylinder of Hyperelastic Bone (HB), which is composed primarily of synthetic hydroxyapatite (hAp), a 3D-printed HB model of the second metacarpal bone (Mc2), and a modern human Mc2 containing nanocrystalline carbonated apatite (cAp). Rietveld refinement was used to determine precise unit-cell parameters aapparent and capparent for each pattern of each scan, and these values determined the actual average 〈a〉 and 〈c〉 for each sample. The results indicate that the 0°/180° rotation method works well enough to uncover variations approaching 1 × 10−3 Å in cAp unit-cell parameters in intact bones with irregular cross sections.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Stock, S.R.Laugesen, M.Birkedal, H.Jakus, A.Shah, R.Park, J.-S.Almer, J.D.2019-02-01doi:10.1107/S1600576718017132International Union of CrystallographyThis article describes a novel but simple and rapid transmission X-ray diffraction method for determining precise unit-cell parameters from thick samples whose mass is irregularly distributed along the beam direction. The approach is demonstrated on two phantoms containing hydroxyapatite and on a human second metacarpal bone which contains carbonated hydroxyapatite.ENX-ray diffractionboneRietveld refinementunit-cell parametershydroxyapatitehuman second metacarpal boneAccurate determination of lattice parameters from X-ray diffraction requires that the diffraction angles be measured very precisely, and significant errors result if the sample–detector separation differs from that assumed. Transmission diffraction from bones, which have a complex cross section and must be left intact, is a situation where this separation is difficult to measure and it may differ from position to position across the specimen. This article describes a method for eliminating the effect of variable sample cross section. Diffraction patterns for each position on the specimen are collected before and after 180° rotation about an axis normal to the cross section of interest. This places the centroid of the diffracting mass at the center of rotation and provides the absolute lattice parameters from the average apparent lattice parameters at the two rotation angles. Diffraction patterns were collected across the cross section of three specimens: a 3D-printed elliptical cylinder of Hyperelastic Bone (HB), which is composed primarily of synthetic hydroxyapatite (hAp), a 3D-printed HB model of the second metacarpal bone (Mc2), and a modern human Mc2 containing nanocrystalline carbonated apatite (cAp). Rietveld refinement was used to determine precise unit-cell parameters aapparent and capparent for each pattern of each scan, and these values determined the actual average 〈a〉 and 〈c〉 for each sample. The results indicate that the 0°/180° rotation method works well enough to uncover variations approaching 1 × 10−3 Å in cAp unit-cell parameters in intact bones with irregular cross sections.text/htmlPrecision lattice parameter determination from transmission diffraction of thick specimens with irregular cross sectionstext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers00Optimization of reflectometry experiments using information theory
http://scripts.iucr.org/cgi-bin/paper?ge5055
A framework based on Bayesian statistics and information theory is developed to optimize the design of surface-sensitive reflectometry experiments. The method applies to model-based reflectivity data analysis, uses simulated reflectivity data and is capable of optimizing experiments that probe a sample under more than one condition. After presentation of the underlying theory and its implementation, the framework is applied to exemplary test problems for which the information gain ΔH is determined. Reflectivity data are simulated for the current generation of neutron reflectometers at the NIST Center for Neutron Research. However, the simulation can be easily modified for X-ray or neutron instruments at any source. With application to structural biology in mind, this work explores the dependence of ΔH on the scattering length density of aqueous solutions in which the sample structure is bathed, on the counting time and on the maximum momentum transfer of the measurement. Finally, the impact of a buried magnetic reference layer on ΔH is investigated.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Treece, B.W.Kienzle, P.A.Hoogerheide, D.P.Majkrzak, C.F.Lösche, M.Heinrich, F.2019-02-01doi:10.1107/S1600576718017016International Union of CrystallographyA framework for the optimization of neutron reflectometry experiments based on Bayesian statistics and information theory is presented.ENneutron reflectometryinformation contentexperimental optimizationA framework based on Bayesian statistics and information theory is developed to optimize the design of surface-sensitive reflectometry experiments. The method applies to model-based reflectivity data analysis, uses simulated reflectivity data and is capable of optimizing experiments that probe a sample under more than one condition. After presentation of the underlying theory and its implementation, the framework is applied to exemplary test problems for which the information gain ΔH is determined. Reflectivity data are simulated for the current generation of neutron reflectometers at the NIST Center for Neutron Research. However, the simulation can be easily modified for X-ray or neutron instruments at any source. With application to structural biology in mind, this work explores the dependence of ΔH on the scattering length density of aqueous solutions in which the sample structure is bathed, on the counting time and on the maximum momentum transfer of the measurement. Finally, the impact of a buried magnetic reference layer on ΔH is investigated.text/htmlOptimization of reflectometry experiments using information theorytext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyresearch papers00Fabrication and characterization of ZnMgO nanowalls grown on 4H-SiC by molecular beam epitaxy
http://scripts.iucr.org/cgi-bin/paper?aj5309
Control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic devices. This paper reports the growth conditions and structural properties of ZnMgO nanowalls grown on the Si face of 4H-SiC substrates by molecular beam epitaxy without catalysts and buffer layers. Images from scanning electron microscopy revealed that the ZnMgO nanowalls are arranged in parallel rows following the stripe morphology of the SiC surface, and their thickness is around 15 nm. The crystal quality of the structures was evaluated by X-ray diffraction measurements.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Pietrzyk, M.A.Wierzbicka, A.Stachowicz, M.Jarosz, D.Kozanecki, A.2019-02-01doi:10.1107/S1600576718016850International Union of CrystallographyThe crystal quality of ZnMgO nanowalls grown on 4H-SiC substrates has been investigated by X-ray diffraction.ENsemiconductorsluminescenceX-ray diffractionzinc oxidemolecular beam epitaxyMBEControl of nanostructure growth is a prerequisite for the development of electronic and optoelectronic devices. This paper reports the growth conditions and structural properties of ZnMgO nanowalls grown on the Si face of 4H-SiC substrates by molecular beam epitaxy without catalysts and buffer layers. Images from scanning electron microscopy revealed that the ZnMgO nanowalls are arranged in parallel rows following the stripe morphology of the SiC surface, and their thickness is around 15 nm. The crystal quality of the structures was evaluated by X-ray diffraction measurements.text/htmlFabrication and characterization of ZnMgO nanowalls grown on 4H-SiC by molecular beam epitaxytext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographyshort communications00Mag2Pol: a program for the analysis of spherical neutron polarimetry, flipping ratio and integrated intensity data
http://scripts.iucr.org/cgi-bin/paper?in5014
Mag2Pol is a graphical user interface program which is devoted to the treatment of data from polarized neutron diffractometers with spherical polarization analysis. Nuclear and magnetic structure models can be introduced using space-group symbols and individual symmetry operators, respectively, and viewed in an OpenGL widget. The program calculates nuclear/magnetic structure factors, flipping ratios and polarization matrices for magnetic Bragg reflections, taking into account structural twins and magnetic domains. Spherical neutron polarimetry data can be analyzed by refining a magnetic structure model including magnetic domain populations in a least-squares fit and can also be correlated with an integrated intensity data set in a joint refinement. Further features are the simultaneous refinement of nuclear and magnetic structures with integrated intensity data and the analysis of flipping ratios either with tabulated magnetic form factors or using a multipole expansion of the magnetization density.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Qureshi, N.2019-02-01doi:10.1107/S1600576718016084International Union of CrystallographyMag2Pol is a graphical user interface program which is devoted to the treatment of data from polarized neutron diffractometers with spherical polarization analysis. A magnetic structure model including magnetic domain populations can be refined in a least-squares fit and can also be correlated with an integrated intensity data set in a joint refinement.ENneutron scatteringmagnetic structuresspherical neutron polarimetrycomputer programsMag2Pol is a graphical user interface program which is devoted to the treatment of data from polarized neutron diffractometers with spherical polarization analysis. Nuclear and magnetic structure models can be introduced using space-group symbols and individual symmetry operators, respectively, and viewed in an OpenGL widget. The program calculates nuclear/magnetic structure factors, flipping ratios and polarization matrices for magnetic Bragg reflections, taking into account structural twins and magnetic domains. Spherical neutron polarimetry data can be analyzed by refining a magnetic structure model including magnetic domain populations in a least-squares fit and can also be correlated with an integrated intensity data set in a joint refinement. Further features are the simultaneous refinement of nuclear and magnetic structures with integrated intensity data and the analysis of flipping ratios either with tabulated magnetic form factors or using a multipole expansion of the magnetization density.text/htmlMag2Pol: a program for the analysis of spherical neutron polarimetry, flipping ratio and integrated intensity datatext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographycomputer programs00Implementation of software for data processing of X-ray optical measurements for the analysis of structural parameters
http://scripts.iucr.org/cgi-bin/paper?te5037
The development of semiconductor nanoelectronic technology requires the use of new approaches to metrological control of critically important stages of device structure formation. The development and use of complex measurement methods based on various physical principles allowing one to obtain exhaustive information about the features of real structures, including the existence of hidden and unaccounted layers in transition areas, are of special interest. This paper presents the idea of implementing a complex approach to X-ray optical studies for a two-wavelength measurement scheme, including the methods of relative X-ray reflectometry, refractometry and diffuse X-ray scattering, and its application to the analysis of dimensional parameters of thin-film structures. The study was carried out with the help of a software package for analysing TiN diffusion-barrier layers. A comparison of the results obtained with the results of one-wavelength methods shows the high efficiency of the implemented approach for performing various tasks of metrological control of nanoelectronic devices.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Petrakov, D.S.Smirnov, D.I.Gerasimenko, N.N.Medetov, N.A.Jikeev, A.A.2019-02-01doi:10.1107/S1600576718016837International Union of CrystallographyA software package for thin-film analysis implemented on the combined basis of two-wavelength X-ray reflectometry, refractometry and diffuse X-ray scattering is proposed.ENsimultaneous complex approachtwo-wavelength X-ray optical methodsthin-film structurescomputer programsThe development of semiconductor nanoelectronic technology requires the use of new approaches to metrological control of critically important stages of device structure formation. The development and use of complex measurement methods based on various physical principles allowing one to obtain exhaustive information about the features of real structures, including the existence of hidden and unaccounted layers in transition areas, are of special interest. This paper presents the idea of implementing a complex approach to X-ray optical studies for a two-wavelength measurement scheme, including the methods of relative X-ray reflectometry, refractometry and diffuse X-ray scattering, and its application to the analysis of dimensional parameters of thin-film structures. The study was carried out with the help of a software package for analysing TiN diffusion-barrier layers. A comparison of the results obtained with the results of one-wavelength methods shows the high efficiency of the implemented approach for performing various tasks of metrological control of nanoelectronic devices.text/htmlImplementation of software for data processing of X-ray optical measurements for the analysis of structural parameterstext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographycomputer programs00refnx: neutron and X-ray reflectometry analysis in Python
http://scripts.iucr.org/cgi-bin/paper?rg5158
refnx is a model-based neutron and X-ray reflectometry data analysis package written in Python. It is cross platform and has been tested on Linux, macOS and Windows. Its graphical user interface is browser based, through a Jupyter notebook. Model construction is modular, being composed from a series of components that each describe a subset of the interface, parameterized in terms of physically relevant parameters (volume fraction of a polymer, lipid area per molecule etc.). The model and data are used to create an objective, which is used to calculate the residuals, log-likelihood and log-prior probabilities of the system. Objectives are combined to perform co-refinement of multiple data sets and mixed-area models. Prior knowledge of parameter values is encoded as probability distribution functions or bounds on all parameters in the system. Additional prior probability terms can be defined for sets of components, over and above those available from the parameters alone. Algebraic parameter constraints are available. The software offers a choice of fitting approaches, including least-squares (global and gradient-based optimizers) and a Bayesian approach using a Markov-chain Monte Carlo algorithm to investigate the posterior distribution of the model parameters. The Bayesian approach is useful for examining parameter covariances, model selection and variability in the resulting scattering length density profiles. The package is designed to facilitate reproducible research; its use in Jupyter notebooks, and subsequent distribution of those notebooks as supporting information, permits straightforward reproduction of analyses.Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Nelson, A.R.J.Prescott, S.W.2019-02-01doi:10.1107/S1600576718017296International Union of CrystallographyThe refnx Python modules for neutron and X-ray reflectometry data analysis are introduced. A sample analysis illustrates a Bayesian approach using a Markov-chain Monte Carlo algorithm to understand the confidence in the fit parameters.ENneutron reflectometryX-ray reflectometryBayesian analysiscomputer modellingrefnxrefnx is a model-based neutron and X-ray reflectometry data analysis package written in Python. It is cross platform and has been tested on Linux, macOS and Windows. Its graphical user interface is browser based, through a Jupyter notebook. Model construction is modular, being composed from a series of components that each describe a subset of the interface, parameterized in terms of physically relevant parameters (volume fraction of a polymer, lipid area per molecule etc.). The model and data are used to create an objective, which is used to calculate the residuals, log-likelihood and log-prior probabilities of the system. Objectives are combined to perform co-refinement of multiple data sets and mixed-area models. Prior knowledge of parameter values is encoded as probability distribution functions or bounds on all parameters in the system. Additional prior probability terms can be defined for sets of components, over and above those available from the parameters alone. Algebraic parameter constraints are available. The software offers a choice of fitting approaches, including least-squares (global and gradient-based optimizers) and a Bayesian approach using a Markov-chain Monte Carlo algorithm to investigate the posterior distribution of the model parameters. The Bayesian approach is useful for examining parameter covariances, model selection and variability in the resulting scattering length density profiles. The package is designed to facilitate reproducible research; its use in Jupyter notebooks, and subsequent distribution of those notebooks as supporting information, permits straightforward reproduction of analyses.text/htmlrefnx: neutron and X-ray reflectometry analysis in Pythontext1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographycomputer programs00Scattering Methods and their Application in Colloid and Interface Science. By Otto Glatter. Elsevier, 2018. Paperback pp. 404. Price USD 225. Paperback (ISBN 9780128135808), ebook (ISBN 9780128135815).
http://scripts.iucr.org/cgi-bin/paper?xo0121
Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Bras, W.Hammel, M.2019-02-01doi:10.1107/S1600576718016023International Union of CrystallographyBook reviewENbook reviewssmall-angle X-ray and neutron scatteringstatic and dynamic light scatteringtext/htmlScattering Methods and their Application in Colloid and Interface Science. By Otto Glatter. Elsevier, 2018. Paperback pp. 404. Price USD 225. Paperback (ISBN 9780128135808), ebook (ISBN 9780128135815).text1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographybook reviews00Structures on Different Time Scales. Edited by T. Woike and D. Schaniel. De Gruyter, 2018. Pp. 272. Hardcover, price EUR 99.95, USD 114.99, GBP 91.00. ISBN 978-3-11-044209-0.
http://scripts.iucr.org/cgi-bin/paper?xo0118
Copyright (c) 2019 International Union of Crystallographyurn:issn:1600-5767Elsaesser, T.2019-02-01doi:10.1107/S1600576718017004International Union of CrystallographyBook reviewENbook reviewsdiffuse scatteringdensity functional theorystructural dynamicsphotocrystallographytext/htmlStructures on Different Time Scales. Edited by T. Woike and D. Schaniel. De Gruyter, 2018. Pp. 272. Hardcover, price EUR 99.95, USD 114.99, GBP 91.00. ISBN 978-3-11-044209-0.text1522019-02-01Copyright (c) 2019 International Union of CrystallographyJournal of Applied Crystallographybook reviews00