Journal of Applied Crystallography

Volume 44, Part 2 (April 2011)

	Cover illustration: Selected images of optical birefringence recorded during the heating of dodecasil-3C crystals. Courtesy of Lethbridge et al. [J. Appl. Cryst. (2010), 43, 168-175].

• research papers
• short communications
• computer programs
• laboratory notes
• meetings

research papers

J. Appl. Cryst. (2011). 44, 265-271  [ doi:10.1107/S0021889811001075 ] The structure factor in small-angle scattering and the effect of deviation from spherical symmetry S. Hansen Synopsis: Spherical symmetry is a frequent assumption when the structure factor is used for data analysis of small-angle scattering data. The present article suggests a correction which may be used for non-spherical scatterers at low volume fractions. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 272-280  [ doi:10.1107/S0021889810054701 ] Towards three-dimensional quantitative reconstruction of cement microstructure by X-ray diffraction microtomography L. Valentini, M. C. Dalconi, M. Parisatto, G. Cruciani and G. Artioli Synopsis: A post-processing method for X-ray diffraction computed microtomography analysis of complex materials is presented. The paper shows the potential of the method in constructing three-dimensional quantitative maps of the individual solid phases present in hydrating cement pastes. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 281-286  [ doi:10.1107/S0021889811004493 ] Measuring the linearity of X-ray detectors: consequences for absolute attenuation, scattering and absolute Bragg intensities Z. Barnea, C. T. Chantler, J. L. Glover, M. W. Grigg, M. T. Islam, M. D. de Jonge, N. A. Rae and C. Q. Tran Synopsis: How to test and verify the required linearity of X-ray detectors is discussed for a wide range of crystallographic and X-ray measurements. Online 22 February 2011

J. Appl. Cryst. (2011). 44, 287-294  [ doi:10.1107/S0021889811006522 ] Real-time synchrotron powder X-ray diffraction study of the antisite defect formation during sub- and supercritical synthesis of LiFePO4 and LiFe1-xMnxPO4 nanoparticles K. Jensen, M. Christensen, C. Tyrsted and B. Brummerstedt Iversen Synopsis: In situ synchrotron powder X-ray diffraction is used to study the formation of LiFePO4 and Li(Fe1-xMnx)PO4 (x = 0.25, 0.50 and 0.75). This technique can be used to follow the influence of time, temperature and manganese doping on the Li-Fe antisite defect concentration, and it is shown that even under supercritical conditions a reaction time of several minutes is required to suppress the defects. Online 10 March 2011

J. Appl. Cryst. (2011). 44, 295-298  [ doi:10.1107/S0021889811005498 ] The ABC of powder diffractometer detector coverage K. H. Andersen, P. M. Bentley and L. D. Cussen Synopsis: It is shown in a general optimization that for a reactor-based constant-wavelength neutron source a diffractometer should not have a large detector solid angle for the best performance. Online 10 March 2011

J. Appl. Cryst. (2011). 44, 299-312  [ doi:10.1107/S0021889811002123 ] Precision of lattice strain and orientation measurements using high-energy monochromatic X-ray diffraction J. K. Edmiston, N. R. Barton, J. V. Bernier, G. C. Johnson and D. J. Steigmann Synopsis: A systematic framework for estimating the uncertainty associated with monochromatic X-ray diffraction-based measurements of the stretch and orientation of a crystalline lattice, using a single full rotation scan, is presented. This framework is validated using a ruby single crystal, and an example application of the technique to a heavily deformed titanium alloy grain embedded in a polycrystal is described. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 313-318  [ doi:10.1107/S0021889811005140 ] Study of the influence of dopants on the crystalline perfection of ferroelectric glycine phosphite single crystals using high-resolution X-ray diffraction analysis K. Senthil Kumar, S. Moorthy Babu and G. Bhagavannarayana Synopsis: Good quality single crystals of pure and doped glycine phosphate were grown by both solvent-evaporation and temperature-cooling techniques. High-resolution X-ray diffraction results confirm the crystalline perfection of the grown crystals. Online 22 February 2011

J. Appl. Cryst. (2011). 44, 319-326  [ doi:10.1107/S0021889811004146 ] Thermal structural properties of calcium tungstate A. Senyshyn, M. Hoelzel, T. Hansen, L. Vasylechko, V. Mikhailik, H. Kraus and H. Ehrenberg Synopsis: The results of in situ temperature-resolved powder diffraction studies confirm the scheelite type of structure for calcium tungstate over a broad temperature range of 5-1773 K. The layered structure formed by two-dimensional CsCl-type arrangements of Ca cations and WO4 complexes is shown to be the primary reason for the observed anisotropy of thermal expansion in calcium tungstate. Online 11 February 2011

J. Appl. Cryst. (2011). 44, 327-336  [ doi:10.1107/S0021889811001968 ] Building and refining complete nanoparticle structures with total scattering data K. Page, T. C. Hood, Th. Proffen and R. B. Neder Synopsis: The use of two programs, DISCUS and DIFFEV, is described and demonstrated for the application of total scattering data to the structure refinement of complete nanoparticle systems. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 337-342  [ doi:10.1107/S0021889811000628 ] Comprehensive upgrade of the high-resolution small-angle neutron scattering instrument KWS-3 at FRM II G. Goerigk and Z. Varga Synopsis: An essential upgrade of the neutron optics of KWS-3 has been performed. Conceptual improvements, such as the extension of the Q range by one order of magnitude and calibration of the scattering curves by the direct-beam method, give access to important structural and quantitative parameters of large-scale structures. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 343-352  [ doi:10.1107/S0021889811003049 ] On the validity of simple precipitate size measurements by small-angle scattering in metallic systems A. Deschamps and F. De Geuser Synopsis: Simple evaluation models for particle size and particle size distribution from small-angle scattering are assessed within the framework of large data sets obtained by time-resolved or scanning experiments on metallic systems. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 353-358  [ doi:10.1107/S0021889811001439 ] X-ray diffracted intensity for double-reflection channel-cut Ge monochromators at extremely asymmetric diffraction conditions C. Ferrari, F. Germini, D. Korytár, P. Mikulík and L. Peverini Synopsis: The X-ray diffracted intensity, Bragg peak width and angular deviation due to refraction have been measured in a channel-cut Ge crystal at angles of incidence near the critical angle. The double-diffracted intensity is very high even near the critical angle. The unexpected broadening of the Bragg peak near the critical angle and the contrast seen in the topographic image of the diffracted beam could be explained by an imperfect surface planarity of the crystal. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 359-369  [ doi:10.1107/S0021889811002858 ] Off-specular data representations in neutron reflectivity F. Ott and S. Kozhevnikov Synopsis: The different methods of data acquisition and representation of off-specular neutron reflectometry measurements are discussed. This is illustrated by diffuse scattering data measured on neutron waveguides on both fixed-wavelength and time-of-flight spectrometers. Online 11 February 2011

J. Appl. Cryst. (2011). 44, 370-379  [ doi:10.1107/S0021889810053823 ] Debye-Scherrer rings from block copolymer films with powder-like order P. Busch, M. Rauscher, J.-F. Moulin and P. Müller-Buschbaum Synopsis: The distortion of Debye-Scherrer rings from powder-like lamellar domains in thin diblock copolymer films due to refraction at grazing angles is discussed within the distorted-wave Born approximation. Online 22 February 2011

J. Appl. Cryst. (2011). 44, 380-384  [ doi:10.1107/S0021889811003578 ] Near-surface relaxation structure of annealed block copolymer film on Si substrates examined by grazing-incidence small-angle scattering utilizing soft X-rays H. Okuda, K. Takeshita, S. Ochiai, S. Sakurai and Y. Kitajima Synopsis: Using grazing-incidence small-angle scattering profiles of an annealed SEBS8 triblock copolymer measured at 1.77 keV, surface-sensitive nanostructure analysis of microphase-separated lattice structures has been demonstrated. The lattice is composed of spherical cores, which are elongated in the out-of-plane direction by 25% within 50 nm from the surface. Online 11 February 2011

J. Appl. Cryst. (2011). 44, 385-391  [ doi:10.1107/S0021889811003980 ] Application of synchrotron-based reciprocal-space mapping at a fixed angular position to identification of crystal symmetry of Bi4Ti3O12 epitaxial thin films O. Sakata, T. Watanabe and H. Funakubo Synopsis: Synchrotron-based reciprocal-space mapping at a fixed angular position was applied to 50 nm-thick and 3 nm-thick Bi4Ti3O12 films that were epitaxically grown on TiO2 (101) substrates. The crystal structures of the films were determined to be monoclinic with a space group of B1a1 or a lower crystal symmetry. Online 22 February 2011

J. Appl. Cryst. (2011). 44, 392-397  [ doi:10.1107/S0021889811006765 ] CYCLOPS - a reciprocal-space explorer based on CCD neutron detectors B. Ouladdiaf, J. Archer, J. R. Allibon, P. Decarpentrie, M.-H. Lemée-Cailleau, J. Rodríguez-Carvajal, A. W. Hewat, S. York, D. Brau and G. J. McIntyre Synopsis: The new single-crystal neutron Laue diffractometer CYCLOPS at the Institut Laue-Langevin combines a large solid angle of detection with the fast readout of CCD detectors to offer a unique instrument for real-time exploration of reciprocal space and rapid data collection through phase transitions. Online 10 March 2011

J. Appl. Cryst. (2011). 44, 398-408  [ doi:10.1107/S0021889811006455 ] Deduction of the single-myosin-filament transforms from partially sampled layer lines in the X-ray diffraction pattern from vertebrate striated muscle K. Oshima, Y. Sugimoto and K. Wakabayashi Synopsis: The single-myosin-filament transform from lattice-sampled layer lines in the X-ray diffraction pattern from vertebrate striated muscle was deduced by the cylindrically averaged difference Patterson function. Online 15 March 2011

J. Appl. Cryst. (2011). 44, 409-413  [ doi:10.1107/S0021889811005115 ] X-ray strain analysis of {111} fiber-textured thin films independent of grain-interaction models D. Faurie, P.-O. Renault, E. Le Bourhis, T. Chauveau, O. Castelnau and P. Goudeau Synopsis: Elastic anisotropy of thin polycrystalline films is difficult and time consuming to approach experimentally and theoretically with available scale transition models. This article proposes an original physical analysis of synchrotron X-ray diffraction data obtained under two particular geometries for {111} fiber texture; this approach allows the accurate determination of single-crystal elastic compliances of thin films. Online 22 February 2011

short communications

J. Appl. Cryst. (2011). 44, 414-417  [ doi:10.1107/S0021889811006790 ] Three-dimensional spatially resolved neutron diffraction from a disordered vortex lattice X. Wang, H. A. Hanson, X. S. Ling, C. F. Majkrzak and B. B. Maranville Synopsis: A novel slicing neutron diffraction technique using atypical collimation and an areal detector is reported. It allows for observing the three-dimensional disorder of the vortex matter inside an as-grown Nb single crystal. Online 10 March 2011

computer programs

J. Appl. Cryst. (2011). 44, 418-423  [ doi:10.1107/S0021889811007102 ] CrystalPlan: an experiment-planning tool for crystallography J. Zikovsky, P. F. Peterson, X. P. Wang, M. Frost and C. Hoffmann Synopsis: This paper describes CrystalPlan, a software program for the automatic creation of crystallography experiment plans for time-of-flight diffractometers. Online 10 March 2011

J. Appl. Cryst. (2011). 44, 424-428  [ doi:10.1107/S0021889811004481 ] Abstractions, algorithms and data structures for structural bioinformatics in PyCogent M. Cieslik, Z. S. Derewenda and C. Mura Synopsis: Flexible abstractions, algorithms and data structures for protein structure analysis have been developed and integrated into the PyCogent bioinformatics software, thereby extending the scope of this sequence-based toolkit to enable combined sequence/structure-based bioinformatic studies. Online 11 February 2011

laboratory notes

J. Appl. Cryst. (2011). 44, 429-432  [ doi:10.1107/S0021889811000525 ] A flow-through reaction cell that couples time-resolved X-ray diffraction with stable isotope analysis A. J. Wall, P. J. Heaney, R. Mathur, J. E. Post, J. C. Hanson and P. J. Eng Synopsis: A design for a non-metallic flow-through sample cell is described. It is useful for combining powder X-ray diffraction with aqueous analysis of mineral-fluid reactions. Online 2 February 2011

J. Appl. Cryst. (2011). 44, 433-436  [ doi:10.1107/S0021889811000045 ] Trimethylamine N-oxide as a versatile cryoprotective agent in macromolecular crystallography C. Mueller-Dieckmann, B. Kauffmann and M. S. Weiss Synopsis: Trimethylamine N-oxide has been applied successfully for cryoprotecting various macromolecular crystals. Online 2 February 2011

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