issue contents

Journal logoJOURNAL OF
ISSN: 1600-5767

June 2002 issue

Highlighted illustration

Cover illustration: The crystal structure of titanite, CaTiOSiO4, viewed down the direction of the octahedral TiO6 chains. The full green lines indicate a unit cell of the two-dimensional Ising model, used to predict diffuse scattering intensity observable in layers normal to the chain direction. Ti atoms are shown in green, Ca in light grey, O in blue. The thinner red lines are Si-O bonds, the thick red lines Ti-O1 bonds. Courtesy of T. Malcherek, C. Paulmann, M. C. Domeneghetti & U. Bismayer [J. Appl. Cryst. (2001), 34, 108-113].

research papers

J. Appl. Cryst. (2002). 35, 291-295
doi: 10.1107/S0021889802002273
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The structure of KMgF3 has been determined by high-resolution neutron powder diffraction at 4.2 K, room temperature and at 10 K intervals from 373 K to 1223 K, and is found to remain cubic at all temperatures. Thermal expansion was fitted using a second-order Grüneisen approximation to the zero-pressure equation of state, while the atomic displacement parameters were found to increase smoothly with temperature and could be fitted using Debye models.

J. Appl. Cryst. (2002). 35, 296-303
doi: 10.1107/S0021889802002844
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The crystal structure of the red polymorph of tetrahexylsexithiophene is solved from X-ray powder diffraction data, using a combination of direct-space Monte Carlo simulated annealing, DFT lattice-energy minimization and Rietveld refinement.

J. Appl. Cryst. (2002). 35, 304-313
doi: 10.1107/S0021889802003035
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The application of the anisotropic Porod law is illustrated for the case of ellipsoidal particles.

J. Appl. Cryst. (2002). 35, 314-318
doi: 10.1107/S0021889802003692
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Propagation of X-ray coherence through dynamical diffraction of a perfect crystal is discussed based on time-dependent Takagi–Taupin equations.

J. Appl. Cryst. (2002). 35, 319-326
doi: 10.1107/S0021889802003837
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A microspectrophotometer is described that allows one to probe protein crystals both in absorption and in fluorescence mode. The results highlight the interest in fluorescence microspectrophotometry for future studies in structural enzymology and protein dynamics.

J. Appl. Cryst. (2002). 35, 327-337
doi: 10.1107/S0021889802004168
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It is shown that the orientation distribution of the fibres in a composite can be determined by deconvolution of the crystallographic texture of the fibre phase in the composite with the crystallographic texture internal to the fibres.

J. Appl. Cryst. (2002). 35, 338-346
doi: 10.1107/S0021889802004156
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The size-broadened profile is modelled in terms of lognormal and gamma distributions of spherical crystallites. The method is applied to two ceria powders, which illustrates shortcomings of the current representation of the size-broadened profile in Rietveld refinement.

J. Appl. Cryst. (2002). 35, 347-355
doi: 10.1107/S0021889802004351
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A novel free-form fit method for unbiased analysis of neutron and X-ray reflectivity data by an evolution strategy cancels out unsystematic features in scattering length density profiles, while it accentuates reliable details.

J. Appl. Cryst. (2002). 35, 356-359
doi: 10.1107/S0021889802005770
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It is shown that incomplete absorption of the X-ray beam in the phosphor of an area detector causes an incident-angle dependence of the recorded X-ray intensities.

J. Appl. Cryst. (2002). 35, 360-363
doi: 10.1107/S0021889802003278
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An instrument for applying strong electric fields to crystal samples during diffraction measurements is described.

short communications

J. Appl. Cryst. (2002). 35, 364-367
doi: 10.1107/S0021889802006027
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Fractional coordinates for structures with known type can be modelled from first principles to about the accuracy of coordinates in routine powder diffraction studies. Powder patterns recalculated from published X-ray cell data and ab initio atom coordinates can then be used for identification of materials just as well as those recalculated from structure results coming from routine X-ray powder studies.

computer programs

J. Appl. Cryst. (2002). 35, 368-370
doi: 10.1107/S0021889802002789
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A procedure is described that will match two or more sets of peaks or atoms related by different origins, enatiomorphs or symmetry elements.

J. Appl. Cryst. (2002). 35, 371-373
doi: 10.1107/S0021889802003230
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WinXPRO, working under the Windows operating system, enables the calculation of crystal and molecular properties using multipole parameters of the electron density.

J. Appl. Cryst. (2002). 35, 374-376
doi: 10.1107/S0021889802005782
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The SnB interface provides users with several multiprocessing options for increasing throughput.

computer program abstracts

J. Appl. Cryst. (2002). 35, 377
doi: 10.1107/S0021889802001449
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The general formalism for diffraction by crystals containing translational or rotational stacking faults is implemented in the program CALCIPOW.

J. Appl. Cryst. (2002). 35, 378
doi: 10.1107/S0021889802003412
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A PC program that checks the symmetry properties of the unit cell and its contents has been added to the package Oscail.

J. Appl. Cryst. (2002). 35, 379
doi: 10.1107/S002188980200506X
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The aim of the program is to generate a complete list of order parameters, both primary and secondary, associated with a given group-subgroup pair of space groups.


J. Appl. Cryst. (2002). 35, 380
doi: 10.1107/S0021889802006805

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