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Journal logoJOURNAL OF
ISSN: 1600-5767

June 2009 issue

Highlighted illustration

Cover illustration: Three-dimensional reconstructed crystal (purple), loop (yellow) and solvent (transparent pink) for a native DNA sample. Courtesy of Brockhauser, Di Michiel, McGeehan, McCarthy & Ravelli [J. Appl. Cryst. (2008), 41, 1057-1066].

research papers

J. Appl. Cryst. (2009). 42, 369-375
doi: 10.1107/S0021889809009145
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Grazing-incidence X-ray diffraction is combined with a two-dimensional pixel detector to obtain three-dimensional reciprocal-space maps of InAs nanowires grown by molecular beam epitaxy.

J. Appl. Cryst. (2009). 42, 376-384
doi: 10.1107/S0021889809008784

J. Appl. Cryst. (2009). 42, 385-391
doi: 10.1107/S0021889809008450
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A modification to the usual least-squares analysis is implemented, to refine structural parameters from powder diffraction data containing an unmodeled impurity. The method is characterized using known materials, and two new structures are refined using the method.

J. Appl. Cryst. (2009). 42, 392-400
doi: 10.1107/S0021889809011492
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The use of high-energy X-rays as a tool to map the diffuse scattering in reciprocal space is discussed. Particular emphasis is put on the influence of multiple scattering effects on the measured intensity distributions.

J. Appl. Cryst. (2009). 42, 401-410
doi: 10.1107/S0021889809006888
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For ideal specimens, thin-film thickness values obtained from high-resolution X-ray diffraction techniques have accuracies of about 1 nm and precisions one or two orders of magnitude smaller. The use of multiple X-ray techniques is required to ensure reliable thickness determination.

J. Appl. Cryst. (2009). 42, 411-415
doi: 10.1107/S002188980901036X
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The etch figures of three forms ({11\overline 20}, {2\overline 1\overline 10} and {10\overline 11}) of the self-frequency-doubling crystal Yb:YAl3(BO3)4 were observed and the point group 32 was displayed. Etch figures of faces or sections with the same indices in Yb:YAl3(BO3)4 and quartz are very similar, although their crystal structures are very different.

J. Appl. Cryst. (2009). 42, 416-428
doi: 10.1107/S0021889809011807
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Supposing the Hill grain-interaction model, it is demonstrated that X-ray elastic constants can be used to determine mechanical elastic constants of cubic fibre-textured thin films. The new approach is demonstrated by the experimental characterization of out-of-plane moduli of fibre-textured Cu and CrN thin films.

J. Appl. Cryst. (2009). 42, 429-432
doi: 10.1107/S0021889809015349
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Hard synchrotron X-ray microdiffraction is used to quantify the orientation distribution of ettringite crystals [Ca6Al2(OH)12(SO4)3·26H2O], which cause cracking and loss of strength in concrete structures.

J. Appl. Cryst. (2009). 42, 433-441
doi: 10.1107/S0021889809015702
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The enantiomorphs of an ambient-pressure superconductor κ-(BEDT-TTF)2Cu(NCS)2 [BEDT-TTF is bis­(ethyl­ene­dithio)­tetra­thia­fulvalene] have been successfully identified using the method of convergent-beam electron diffraction. This indicates that a micrometre-sized small crystallite is enough to identify its enantiomorphs even in an organic crystal. Stacking faults in κ-(BEDT-TTF)2Cu(NCS)2 have also been found, the existence of which has not been noted from conventional X-ray diffraction methods.

J. Appl. Cryst. (2009). 42, 442-447
doi: 10.1107/S0021889809012412
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The decrease of average atomic coordination number with size in nanocrystals is evaluated using calculations based on ideal spherical crystals.

J. Appl. Cryst. (2009). 42, 448-456
doi: 10.1107/S0021889809011947
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The size distribution and morphology of silicon nanoparticles have been studied using small-angle X-ray scattering and transmission electron microscopy. Milled particles exhibit surface fractal characteristics and a high size dispersion, whereas particles produced by silane pyrolysis are smooth with a monodisperse distribution.

J. Appl. Cryst. (2009). 42, 457-460
doi: 10.1107/S0021889809010036
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The development of a prototype environmental gas cell, capable of allowing a single crystal to be exposed to different gas mixtures and/or a vacuum whilst in situ on the single-crystal diffractometer, is reported along with an initial case study.

J. Appl. Cryst. (2009). 42, 461-468
doi: 10.1107/S0021889809007456
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Small-angle neutron scattering (SANS) studies of glucose/xylose isomerase indicate that the structure of this protein in solution is very stable and very similar to that in the crystal, in a broad pressure range up to 150 MPa. This enzyme can be used as a secondary standard for SANS measurements.

J. Appl. Cryst. (2009). 42, 469-479
doi: 10.1107/S0021889809008802
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The design and operation of a versatile ultra-small-angle X-ray scattering instrument at the Advanced Photon Source at Argonne National Laboratory are presented.

J. Appl. Cryst. (2009). 42, 480-484
doi: 10.1107/S0021889809008310
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The recent interpretation in the literature of the diffraction pattern of top-seeded BaTiO3 as a hybrid structure of monoclinic and tetragonal phases is dismissed in favour of a twinning model, which has been derived from single-crystal CCD diffraction data and confirmed by simulations. BaTiO3 at room temperature is proved conclusively to be a single phase of tetragonal symmetry.

J. Appl. Cryst. (2009). 42, 485-489
doi: 10.1107/S0021889809008966
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A new high-performance diffracted-beam analyzer consisting of multiple pieces of a perfect crystal in the form of a simple and compact device is proposed. The X-ray intensity diffracted from the analyzer can be increased by, for example, one order of magnitude compared with that obtained with an ordinary single-crystal analyzer.

J. Appl. Cryst. (2009). 42, 490-495
doi: 10.1107/S0021889809010085
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An approach to correct for the effect of sample displacement from the Bragg plane on peak position is described for reflection-mode Debye–Scherrer geometry and applied to determine the relationship between composition and lattice parameter in Smx/2Ndx/2Ce1−xO2−δ ceramics.

J. Appl. Cryst. (2009). 42, 496-501
doi: 10.1107/S0021889809010747
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Measuring the anisotropic properties of materials, such as phonon densities of states, is possible on an anisotropic polycrystal with a well known orientation distribution function (ODF). With this purpose, the ODF is characterized by Rietveld and Mössbauer texture analysis.

J. Appl. Cryst. (2009). 42, 502-512
doi: 10.1107/S0021889809008681
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Energy-dispersive diffraction data from the Synchrotron Radiation Source at Daresbury Laboratories have been analysed using crystal-structure-based Rietveld refinement. A standardless quantification method has been developed to analyse directly in energy space rather than in d space. Standard mixtures have been quantified to verify the method which has then been applied to a tomographic study of an electrochemical cell.

J. Appl. Cryst. (2009). 42, 513-518
doi: 10.1107/S0021889809013727
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An analytic expression has been derived which connects the degree of preferred orientation in a polycrystalline material to the March parameter. The latter defines the spread of angular distribution of crystallite inclinations in the March–Dollase approach.

J. Appl. Cryst. (2009). 42, 519-524
doi: 10.1107/S0021889809013107
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A general method to determine the surface crystallography and therefore the shape of faceted nanoparticles by transmission electron microscopy is proposed.

cryocrystallography papers

J. Appl. Cryst. (2009). 42, 525-530
doi: 10.1107/S0021889809011315
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The minimal concentrations of three common cryoprotectants were determined for high-pressure cryocooling of water in thick-walled plastic capillaries. The substantial reduction in the minimal concentrations by high-pressure cryocooling can be of significant use in high-throughput X-ray protein structure determination.

short communications

J. Appl. Cryst. (2009). 42, 531-534
doi: 10.1107/S0021889809009157
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This paper describes the design of various sample cells providing a controlled environment for small single crystals or epitaxial thin films during diffraction experiments.

J. Appl. Cryst. (2009). 42, 535-537
doi: 10.1107/S0021889809013430
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A novel method that enables single-crystal diffraction data to be obtained from a powder sample is presented.

computer programs

J. Appl. Cryst. (2009). 42, 538-539
doi: 10.1107/S0021889809008309
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The ReX software provides a user-friendly environment for structural analysis using powder diffraction data.

J. Appl. Cryst. (2009). 42, 540-544
doi: 10.1107/S0021889809012370
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HATODAS II, which provides comprehensive suggestions for the heavy-atom derivatization of protein crystals, is described.

laboratory notes

J. Appl. Cryst. (2009). 42, 545-546
doi: 10.1107/S0021889809014149
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A model of an air cooler in a laboratory furnace is presented. The setup allows for simultaneous regulation of different crystallization fronts and rates in crucible columns, enabling rapid acquisition of crystals in an undergraduate laboratory.

addenda and errata

J. Appl. Cryst. (2009). 42, 547
doi: 10.1107/S0021889809015660


J. Appl. Cryst. (2009). 42, 548
doi: 10.1107/S002188980901139X

J. Appl. Cryst. (2009). 42, 549
doi: 10.1107/S0021889809017270

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