Journal of Applied Crystallography

 

J. Appl. Cryst. (1998). 31, 647-653  [ doi:10.1107/S0021889897016439 ]

Use of Image-Processing Tools for Texture Analysis of High-Energy X-ray Synchrotron Data

R. Fisker, H. F. Poulsen, J. Schou, J. M. Carstensen and S. Garbe

Synopsis: An automatic method for the estimation of the parameters of the trace of the Debye-Scherrer cones on a two-dimensional detector and for integrating the intensity along the Debye-Scherrer cones is presented.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 654-662  [ doi:10.1107/S0021889898000363 ]

Étude par Diffraction X des Modes d'Empilement de la Nacrite Hydratée et Deshydratée

A. Ben Haj Amara, J. Ben Brahim, A. Plançon and H. Ben Rhaiem

Synopsis: The structure of the 8.4  Å hydrated and dehydrated nacrite was determined by X-ray diffraction.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 663-671  [ doi:10.1107/S0021889898001629 ]

Structural Change Caused by Substitution of Nd for Sm in (Nd, Sm)AlO₃: Application of Synchrotron High-Resolution Powder X-ray Diffraction

A. Saitow, A. Yoshikawa, H. Horiuchi, T. Shishido, T. Fukuda, M. Tanaka, T. Mori and S. Sasaki

Synopsis: Synchrotron high-resolution X-ray powder diffraction was applied to analyse structural behaviour of the perovskite-type solid solution of (Nd, Sm)AlO₃. A very small change in ionic radius of R gives a remarkable effect on the structure.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 672-682  [ doi:10.1107/S0021889898002702 ]

A Wide-Bandpass Multilayer Monochromator for Biological Small-Angle Scattering and Fiber Diffraction Studies

H. Tsuruta, S. Brennan, Z. U. Rek, T. C. Irving, W. H. Tompkins and K. O. Hodgson

Synopsis: A wide-bandpass synchrotron X-ray monochromator with a pair of synthetic multilayers has been characterized and utilized for small-angle X-ray scattering studies of biological fibers, lipid and protein solutions. It provides an increase in flux by a factor of 10-30 compared with an Si(111) monochromator. The wide-bandpass monochromator produces no change in background level nor in small-angle resolution; there is an insignificant degree of diffraction peak broadening.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 683-691  [ doi:10.1107/S0021889898003550 ]

High-Order Incommensurate Modulations and Incommensurate Superstructures in Transparent Sr_0.6Ba_0.4Nb₂O₆ (SBN40) Ceramics

H.-Y. Lee and R. Freer

Synopsis: Ceramics of strontium barium niobate were investigated by transmission electron microscopy; the lowest order incommensurate superstructure (ICS) modulation was observed inall samples. Transparent ceramics which exhibited large grains were characterized by a shortened c axis and higher order ICS reflections.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 692-699  [ doi:10.1107/S0021889898003690 ]

Accurate Site Occupancies for Light Atoms from Powder X-ray Data? Oxygen/Vacancy Ordering in 6H-BaFe_0.67Ti_0.33O_3- ( = 0.08 and 0.32)

I. E. Grey, L. M. D. Cranswick and C. Li

Synopsis: The accuracy of site-occupancy results for light atoms obtained from powder X-ray data refinements was investigated for the case of the oxygen-deficient 6H-hexagonal ferrites, BaFe_0.67Ti_0.33O_{3 -} ( = 0.08 and 0.32).

Online October 1998

 

J. Appl. Cryst. (1998). 31, 700-707  [ doi:10.1107/S0021889898003227 ]

Determination of the Anomalous Scattering Factors in the Soft-X-ray Range using Diffraction from a Multilayer

L. Sève, J. M. Tonnerre and D. Raoux

Synopsis: Bragg diffraction from an Ag/Ni multilayer was used to determine independently both the real and imaginary parts of the anomalous scattering factor (ASF) around the Ni L_III and L_II edges in the soft-X-ray range. Huge resonant variations were observed with reaching 55 and decreasing to -63 at the Ni L_III edge.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 708-717  [ doi:10.1107/S0021889898004361 ]

The Use of Partial Reflections for Scaling and Averaging X-ray Area-Detector Data

R. Bolotovsky, I. Steller and M. G. Rossmann

Synopsis: The Hamilton, Rollett and Sparks procedure for scaling frames of X-ray area-detector data has been generalized to utilize partial reflections. The new scaling methods have been shown to work successfully on data-sets collected from crystals of biological macromolecules.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 718-725  [ doi:10.1107/S0021889898004324 ]

Refinement of the Ferri- and Paramagnetic Phases of Magnetite from Neutron Multiple Diffraction Data

V. L. Mazzocchi and C. B. R. Parente

Synopsis: Structural parameters for the ferri- and paramagnetic phases of magnetite have been refined from neutron multiple diffraction (NMD) data. The refinements were done by comparing experimental NMD patterns, obtained with a single crystal of this compound, at room temperature for the ferrimagnetic phase and at 976  K for the paramagnetic phase, with corresponding simulated patterns.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 726-732  [ doi:10.1107/S0021889898004403 ]

Two- and Three-Beam X-ray Diffraction Imaging of Domains in Magnetite

C. Medrano, F. Heyroth, M. Schlenker, J. Baruchel and J. Espeso

Synopsis: High angular sensitivity is obtained in white-beam topographs made on a weak reflection when it is enhanced through Umweganregung by strong reflection.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 733-741  [ doi:10.1107/S0021889898004439 ]

Focusing Mirrors for Use with Microfocus X-ray Tubes

U. W. Arndt, P. Duncumb, J. V. P. Long, L. Pina and A. Inneman

Synopsis: The focusing mirrors described here used with low-power microfocus X-ray tubes in single-crystal diffractometry can produce a flux at the sample which is comparable with that obtained with conventional X-ray sources at a power 100 times greater.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 742-747  [ doi:10.1107/S0021889898004956 ]

High-resolution Neutron Diffraction using Larmor Precession

W. H. Kraan, C. T. Kaiser and M. Th. Rekveldt

Synopsis: A novel technique for obtaining neutron spectra is described. It is applied in a simultaneous diffraction experiment at 32 positions over the thickness of a sample. Comparison of the results with those of a reference experiment with a slightly different geometry reveals the lattice deformation over the sample thickness.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 748-757  [ doi:10.1107/S0021889898004968 ]

Anisotropy of Intermolecular Interactions from the Study of the Thermal-Expansion Tensor

J. Salud, M. Barrio, D. O. López, J. L. Tamarit and X. Alcobé

Synopsis: The anisotropy of the intermolecular interactions in the low-temperature ordered phases has been studied for three chemically and structurally related compounds: (CH₃)₂C(CH₂OH)₂, (CH₃)₃C(COOH) and (CH₃)₃C(CH₂OH). The volume expansivity and the packing coefficient have also been studied, both as a function of temperature, in the low- and in the high-(orientationally disordered)-temperature phases of these compounds.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 758-766  [ doi:10.1107/S0021889898005287 ]

New Developments in Instrumentation for X-ray and Neutron Fibre Diffraction Experiments

M. W. Shotton, L. H. Pope, V. T. Forsyth, R. C. Denny, J. Archer, P. Langan, H. Ye and C. Boote

Synopsis: Experimental and data reduction procedures that optimize sample environment and data collection are described. These procedures are structured to the CCP13 standard and are of general applicability in X-ray and neutron fibre diffraction experiments.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 767-776  [ doi:10.1107/S0021889898005317 ]

Twinning in Natural Diamond. I. Contact Twins

A. Yacoot, M. Moore and W. G. Machado

Synopsis: Growth histories of various kinds of (111) contact twins in natural diamond have been deduced from X-ray topographic studies.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 777-782  [ doi:10.1107/S0021889898005329 ]

Twinning in Natural Diamond. II. Interpenetrant Cubes

W. G. Machado, M. Moore and A. Yacoot

Synopsis: Interpenetrant cubes of natural diamond have been formed by fibrous growth upon a twin origin.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 783-788  [ doi:10.1107/S0021889898005640 ]

Structural Evolution of Ag-Co and Ag-Ni Alloys Studied by Anomalous Small-Angle X-ray Scattering

C. Revenant-Brizard, J. P. Simon, J. R. Regnard, I. Manzini and B. Rodmacq

Synopsis: Anomalous small-angle X-ray scattering revealed the microstructure of the transition metal particles in co-sputtered Ag-20 (and 35)  at.% Co and Ag-20 (and 35)  at.% Ni in the as-deposited state and after different anneals for 10  min at 573, 623 and 723  K.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 789-797  [ doi:10.1107/S0021889898006293 ]

The Application of Resonant Scattering Techniques to Ab Initio Structure Solution from Powder Data using SrSO₄ as a Test Case

K. Burger, D. Cox, R. Papoular and W. Prandl

Synopsis: With only a powder sample available, resonant (anomalous) scattering of X-rays from a synchrotron source can be used to determine phases of structure factors directly and thus can be used for the ab initio structure determination of unknown crystal structures. The method is described in detail using the orthorhombic structure of SrSO₄ as an example.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 798-805  [ doi:10.1107/S0021889898006645 ]

Phase Improvement by Multi-Start Simulated Annealing Refinement and Structure-Factor Averaging

L. M. Rice, Y. Shamoo and A. T. Brünger

Synopsis: A method using multi-start simulated annealing refinement followed by structure-factor averaging is presented. Electron-density maps calculated using the average structure factor show less model bias than those computed from individual models.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 806-811  [ doi:10.1107/S0021889898004166 ]

Applications of Polycapillary X-ray Optics in Protein Crystallography

P.-W. Li and R.-C. Bi

Synopsis: A kind of polycapillary X-ray optics has been applied to data collection for protein crystals, and much better quality intensities could be obtained than those achieved with Supper double focusing mirrors on the same laboratory X-ray source.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 812-814  [ doi:10.1107/S0021889898003513 ]

A cell for producing xenon-derivative crystals for cryocrystallographic analysis

K. Djinovic-Carugo, P. Everitt and P. A. Tucker

Synopsis: A pressure cell is described for binding xenon to protein crystals mounted in freely suspended thin films prior to flash cooling, thus trapping the xenon in the crystals.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 815-817  [ doi:10.1107/S0021889898003537 ]

An open-flow helium cryostat for single-crystal X-ray diffraction experiments

M. J. Hardie, K. Kirschbaum, A. Martin and A. A. Pinkerton

Synopsis: An open-flow helium cryostat for single-crystal X-ray diffraction experiments capable of reaching 14  K has been developed using off-the-shelf components.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 818-819  [ doi:10.1107/S0021889898003914 ]

A note on mean orientation

A. Morawiec

Synopsis: A new method of calculating the mean orientation is presented.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 820-822  [ doi:10.1107/S0021889898004683 ]

Harmonic composition of synchrotron white-beam X-ray topographic back-reflection images of basal-cut silicon carbide single-crystal wafers

W. M. Vetter and M. Dudley

Synopsis: The harmonic content of back-reflection X-ray topographs of SiC single crystals taken using synchrotron white-beam radiation is analyzed with respect to the origins of the contrast of this kind of topograph.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 823-825  [ doi:10.1107/S002188989800538X ]

A neutron diffraction cell for studying lithium-insertion processes in electrode materials

Ö. Bergstöm, A. M. Andersson, K. Edström and T. Gustafsson

Synopsis: An electrochemical cell has been constructed for in situ neutron diffraction studies of lithium insertion/extraction processes in electrode materials for Li-ion batteries.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 826  [ doi:10.1107/S0021889897012715 ]

POWDIS and POWUTL - PC programs for the display and simulation of X-ray powder patterns

P. McArdle and D. Cunningham

Synopsis: PC programs for the display and simulation of X-ray powder patterns are presented.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 826-827  [ doi:10.1107/S0021889897012739 ]

VALMAP 1.0 - a program for the calculation and visualization of contour maps of bond-valence sums

J. González-Platas and C. González-Silgo

Synopsis: A graphical program for maps of bond-valence sums is presented.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 827-828  [ doi:10.1107/S0021889897019468 ]

CARAT - a package for mathematical crystallography

W. Plesken, J. Opgenorth and T. Schulz

Synopsis: A software package for mathematical crystallography is presented.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 828  [ doi:10.1107/S0021889897011035 ]

DECA-ZONAX: a program for indexing zone-axis patterns of decagonal quasicrystals

S. Weber and A. Singh

Synopsis: A program for indexing zone-axis patterns of decagonal quasicrystals is presented. It is based on the algorithms of Singh and Ranganathan.

Online October 1998

 

J. Appl. Cryst. (1998). 31, 828  [ doi:10.1107/S0021889898009091 ]

International Centre for Diffraction Data -Officers and Directors for 1998

Online October 1998

 

J. Appl. Cryst. (1998). 31, 828  [ doi:10.1107/S0021889898004865 ]

Inorganic materials

Online October 1998