Journal of Applied Crystallography

 

J. Appl. Cryst. (2011). 44, 441-447  [ doi:10.1107/S0021889811009617 ]

Small-angle scattering from spindle-shaped colloidal hematite particles in external magnetic fields

C. Märkert, B. Fischer and J. Wagner

Synopsis: In the presence of phosphate anions, colloidal single-crystalline hematite particles grow as spindle-shaped particles whose aspect ratio can be tuned via the phosphate concentration. Because of the canted antiferromagnetism of hematite, the particles align with the long axis perpendicular to the external field, thereby inducing an isotropic-nematic phase transition in dilute suspensions.

Online 22 April 2011

 

J. Appl. Cryst. (2011). 44, 448-453  [ doi:10.1107/S0021889811010727 ]

Advances in the EXPO2009 systematic decomposition procedure: an atom-matching-based figure of merit

A. Altomare, C. Cuocci, C. Giacovazzo, A. Moliterni and R. Rizzi

Synopsis: A new strategy is described aiming at identifying the correct structure models among a large number of feasible trials generated by the application of direct methods to structure factor moduli estimated by a powder pattern systematic decomposition procedure.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 454-461  [ doi:10.1107/S0021889811012106 ]

Quantitative texture analysis from powder-like electron diffraction data

M. Gemmi, M. Voltolini, A. M. Ferretti and A. Ponti

Synopsis: A complete texture analysis of an Al thin film and of -MnS nanocrystals deposited on a carbon film grid has been carried out using the Rietveld procedure embedded in the software MAUD working on a set of powder electron diffraction patterns taken in different orientations.

Online 22 April 2011

 

J. Appl. Cryst. (2011). 44, 462-466  [ doi:10.1107/S0021889811012532 ]

Investigation by coherent X-ray section topography of ferroelectric domain behaviour as a function of temperature in periodically poled Rb:KTP

F. Masiello, T. A. Lafford, P. Pernot, J. Baruchel, D. S. Keeble, P. A. Thomas, A. Zukauskas, G. Strömqvist, F. Laurell and C. Canalias

Synopsis: The observed evolution of ferroelectric domains in Rb-doped potassium titanyl phosphate (KTP) as the Curie temperature is approached is explained by competition between a built-in electric field and the coercive field.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 467-472  [ doi:10.1107/S0021889811013227 ]

Optimum velocity of a phase-space transformer for cold-neutron backscattering spectroscopy

M. Hennig, B. Frick and T. Seydel

Synopsis: Analytical considerations are compared with numerical simulations regarding the optimum velocity of a moving mosaic crystal used to achieve a phase-space transformation.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 473-482  [ doi:10.1107/S0021889811013343 ]

Structure of PEP-PEO block copolymer micelles: exploiting the complementarity of small-angle X-ray scattering and static light scattering

G. V. Jensen, Q. Shi, M. J. Hernansanz, C. L. P. Oliveira, G. R. Deen, K. Almdal and J. S. Pedersen

Synopsis: The structure of poly(ethylene propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer micelles is determined by combining static light and small-angle X-ray scattering. These two techniques employ different contrasts and provide information on, respectively, large and short length scales.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 483-488  [ doi:10.1107/S0021889811013124 ]

Global optimization of an entire neutron guide hall

P. M. Bentley, P. Fouquet, M. Böhm, I. Sutton, C. D. Dewhurst and K. H. Andersen

Synopsis: This paper describes how two modern computational techniques can be used together to optimize an entire neutron guide system, in this example the H5 guide system at the Institut Laue-Langevin.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 489-494  [ doi:10.1107/S0021889811012088 ]

Thermal slip sources at the extremity and bevel edge of silicon wafers

B. K. Tanner, J. Wittge, D. Allen, M. C. Fossati, A. N. Danilwesky, P. McNally, J. Garagorri, M. R. Elizalde and D. Jacques

Synopsis: Sources of thermal slip have been identified at the extremity and bevel edge of large-diameter silicon wafers. The short duration of rapid thermal annealing prevents the propagation of these dislocations in the body of the wafer, rather than suppressing nucleation.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 495-502  [ doi:10.1107/S0021889811016050 ]

Microstructural changes in porous hematite nanoparticles upon calcination

R. E. Johnsen, K. D. Knudsen and A. M. Molenbroek

Synopsis: This combined study using small-angle neutron scattering, X-ray powder diffraction, transmission electron microscopy and adsorption isotherm techniques demonstrates radical changes in the microstructure of porous hematite nanoparticles upon calcination in air.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 503-513  [ doi:10.1107/S0021889811013021 ]

Inhomogeneous dynamic nuclear polarization of protons in a lamella-forming diblock copolymer investigated by a small-angle neutron scattering method

Y. Noda, T. Kumada, T. Hashimoto and S. Koizumi

Synopsis: The inhomogeneity of proton polarization induced by dynamic nuclear polarization in a lamella-forming diblock copolymer film has been precisely evaluated by small-angle neutron scattering.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 514-525  [ doi:10.1107/S0021889811012696 ]

Back-reflection energy-dispersive X-ray diffraction: a novel diffraction technique with almost complete insensitivity to sample morphology

G. M. Hansford

Synopsis: A novel X-ray diffraction technique with remarkable insensitivity to the sample morphology is described for the first time. The technique is based on energy-dispersive X-ray diffraction in a back-reflection geometry.

Online 22 April 2011

 

J. Appl. Cryst. (2011). 44, 526-531  [ doi:10.1107/S0021889811013264 ]

Three-dimensional X-ray diffraction imaging of process-induced dislocation loops in silicon

D. Allen, J. Wittge, J. Stopford, A. Danilewsky and P. McNally

Synopsis: Utilizing freely available image processing software combined with medical tomography algorithms the three-dimensional structure of dislocation loops in silicon can be examined. The rendered images can be rotated to examine the loops from any desired projection.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 532-539  [ doi:10.1107/S0021889811001609 ]

Treatment of hydrogen background in bulk and nanocrystalline neutron total scattering experiments

K. Page, C. E. White, E. G. Estell, R. B. Neder, A. Llobet and Th. Proffen

Synopsis: A method is presented for the correction of crystalline, amorphous powder and nanoparticle neutron total scattering data with large amounts of nuclear incoherent scattering from hydrogen. The effects of correction on experimental atomic pair distribution function data sets are evaluated and the value of such corrections for several samples is demonstrated.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 540-544  [ doi:10.1107/S0021889811014208 ]

Theory of X-ray reflection broadening for textures with double-axis averaging: from semicrystalline polymers exhibiting twisted lamellar growth to discotic liquid crystals

V. Luchnikov, D. Anokhin, S. Z. D. Cheng, C.-L. Wang, G. Bar and D. A. Ivanov

Synopsis: It is shown that textures with double-axis averaging similar to the a-texture, or Keller-Machin Type I texture, are not specific to semicrystalline polymers exhibiting twisted lamellar growth; the same texture is observed in extruded fibers of a typical discotic molecule, trans-diC₆₀-Zn porphyrin. The characteristic `comma'-like azimuthal intensity profiles of the non-equatorial diffraction peaks in two-dimensional X-ray patterns are described using a simple analytical model, which shows good agreement with experiment.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 545-557  [ doi:10.1107/S0021889811011691 ]

Scattering functions of Platonic solids

X. Li, C.-Y. Shew, L. He, F. Meilleur, D. A. A. Myles, E. Liu, Y. Zhang, G. S. Smith, K. W. Herwig, R. Pynn and W.-R. Chen

Synopsis: The first systematic theoretical study regarding the small-angle scattering properties of the Platonic solids, including the tetrahedron, hexahedron, octahedron, dodecahedron and icosahedron, is presented, and the general characteristics of the single-particle spatial correlation functions corresponding to the Platonic systems with different sphericities are discussed.

Online 27 April 2011

 

J. Appl. Cryst. (2011). 44, 558-568  [ doi:10.1107/S0021889811007527 ]

Modernization of the small-angle neutron scattering spectrometer SANS-U by upgrade to a focusing SANS spectrometer

H. Iwase, H. Endo, M. Katagiri and M. Shibayama

Synopsis: The small-angle neutron scattering spectrometer SANS-U has been successfully upgraded from a conventional pinhole small-angle neutron scattering spectrometer to a focusing small-angle neutron scattering spectrometer.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 569-573  [ doi:10.1107/S0021889811013744 ]

The first find of dodecagonal quasiperiodic tiling in historical Islamic architecture

E. Makovicky and N. M. Makovicky

Synopsis: The entrance to the Zaouïa Moulay Idriss II in Fez, Morocco, contains the only known example of a dodecagonal quasiperiodic cartwheel pattern in Islamic art. Its geometry satisfies the dodecagonal Ammann quasilattice and is close to the geometry of a diffraction pattern from a dodecagonal quasicrystal.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 574-584  [ doi:10.1107/S0021889811012908 ]

Real-time microstructure of shock-compressed single crystals from X-ray diffraction line profiles

S. J. Turneaure and Y. M. Gupta

Synopsis: X-ray diffraction and associated analysis methods are described for examining the real-time microstructure of shock-compressed single crystals. The methods are demonstrated for an Al(100) crystal shock compressed to 7.1 GPa.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 585-594  [ doi:10.1107/S0021889811013458 ]

The ferroelectric properties of Cd₂Nb₂O₇: a Monte Carlo simulation study

T. Malcherek

Synopsis: The order-disorder contributions to the ferroelectric properties of Cd₂Nb₂O₇ have been studied by Monte Carlo simulation of a 12-state modified Potts model on the pyrochlore lattice.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 595-602  [ doi:10.1107/S0021889811012131 ]

Triclinic and monoclinic structures of SrLaCuNbO₆ and SrLaCuTaO₆ double perovskites

D. V. West and P. K. Davies

Synopsis: The crystal structures are reported for SrLaCuNbO₆ and SrLaCuTaO₆, refined from neutron and synchrotron X-ray powder diffraction data at variable temperatures. Profile analysis and electron diffraction indicate significant local-scale behavior in these materials.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 603-609  [ doi:10.1107/S0021889811012635 ]

Diffuse scattering from the lead-based relaxor ferroelectric PbMg_1/3Ta_2/3O₃

A. Cervellino, S. N. Gvasaliya, O. Zaharko, B. Roessli, G. M. Rotaru, R. A. Cowley, S. G. Lushnikov, T. A. Shaplygina and M. T. Fernandez-Diaz

Synopsis: The relaxor ferroelectric PbMg_1/3Ta_2/3O₃ was studied by single-crystal neutron and synchrotron X-ray diffraction, and its detailed atomic structure modelled in terms of static Pb displacements that lead to the formation of polar nanoregions.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 610-617  [ doi:10.1107/S0021889811012829 ]

A uniaxial tensile stage with tracking capabilities for micro X-ray diffraction applications

P. A. Lynch, D. Parry, D. Liang, R. Kirkham, P. Davey, A. W. Stevenson, C. J. Bettles, M. A. Gibson and D. Tomus

Synopsis: The development of a uniaxial tensile loading stage with optical tracking capabilities for X-ray microdiffraction experimentation is detailed. Stage testing was carried out using a polycrystalline commercial-purity Ti sample. Synchrotron X-ray microdiffraction results indicated that the elastic-plastic response of individual grains could be measured with submicrometre spatial resolution.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 618-624  [ doi:10.1107/S0021889811008223 ]

Incoherent neutron scattering from multi-element materials

C. J. Glinka

Synopsis: The differences and distinguishing characteristics of incoherent scattering vis-à-vis diffuse coherent scattering due to atomic disorder are delineated and demonstrated experimentally.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 625-627  [ doi:10.1107/S0021889811012404 ]

Initial elemental analysis by X-ray crystallography

J. Feng

Synopsis: It is shown that atom species of a crystal can be quantitatively retrieved from X-ray diffraction data.

Online 22 April 2011

 

J. Appl. Cryst. (2011). 44, 628-634  [ doi:10.1107/S0021889811011058 ]

CIFXML: a schema and toolkit for managing CIFs in XML

N. E. Day, P. Murray-Rust and S. M. Tyrrell

Synopsis: A toolkit for conversion of CIF documents into complete semantic XML documents is presented.

Online 14 May 2011

 

J. Appl. Cryst. (2011). 44, 635-640  [ doi:10.1107/S0021889811009009 ]

Fast computation of scattering maps of nanostructures using graphical processing units

V. Favre-Nicolin, J. Coraux, M.-I. Richard and H. Renevier

Synopsis: Scattering calculations from atomistic models using graphical processing units are presented and compared with the speed achieved using normal central processing unit calculations. An open-source software toolbox (PyNX) is presented, with a few examples showing the fast calculation of scattering maps from strained nanostructures, including grazing-incidence conditions.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 641-646  [ doi:10.1107/S0021889811012064 ]

StressTextureCalculator: a software tool to extract texture, strain and microstructure information from area-detector measurements

C. Randau, U. Garbe and H.-G. Brokmeier

Synopsis: The software StressTextureCalculator (STeCa) was designed to facilitate fast, easy and automated access to area-detector data. Its outstanding features are direct calculation of diffraction patterns from different types of area-detector measurements, automatic data treatment and peak fitting using several implemented fit options.

Online 22 April 2011

 

J. Appl. Cryst. (2011). 44, 647-650  [ doi:10.1107/S0021889811009393 ]

RPS: Repeats in Protein Sequences

V. Babu, M. Uthayakumar, M. Kirti Vaishnavi, R. Senthilkumar, M. Shankar, C. Archana, S. Sathya Priya and K. Sekar

Synopsis: A computing resource (a web server and a database), Repeats in Protein Sequences (RPS), has been created. Using RPS, users can obtain useful information regarding identical, similar and distant repeats in protein sequences, check the frequency of occurrence of the repeats in several sequence databases, and view the three-dimensional structure of the repeats using the Java visualization plug-in Jmol.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 651-654  [ doi:10.1107/S0021889811008387 ]

BSSB: BLAST Server for Structural Biologists

M. Uthayakumar, G. Sowmiya, R. Sabarinathan, N. Udayaprakash, M. Kirti Vaishnavi and K. Sekar

Synopsis: The Basic Local Alignment Search Tool (BLAST) is one of the most widely used sequence alignment programs, but none of the existing tools for processing BLAST output provide three-dimensional structure visualization. This shortcoming has been addressed in the proposed tool BLAST Server for Structural Biologists (BSSB), which maps a BLAST output onto the three-dimensional structure of the subject protein.

Online 2 April 2011

 

J. Appl. Cryst. (2011). 44, 655-658  [ doi:10.1107/S0021889811012301 ]

Four-circle single-crystal neutron diffractometer at the High Flux Isotope Reactor

B. C. Chakoumakos, H. Cao, F. Ye, A. D. Stoica, M. Popovici, M. Sundaram, W. Zhou, J. S. Hicks, G. W. Lynn and R. A. Riedel

Synopsis: The upgraded single-crystal neutron diffractometer at the High Flux Isotope Reactor, Oak Ridge National Laboratory, is well suited for nuclear and magnetic structural studies. Both high-intensity and high-resolution modes are possible by changing the horizontal bending of the monochromator.

Online 6 May 2011

 

J. Appl. Cryst. (2011). 44, 659  [ doi:10.1107/S0021889811017043 ]

The mystery of the giant crystals

Online 14 May 2011