issue contents

Journal logoJOURNAL OF
ISSN: 1600-5767

April 1995 issue

Highlighted illustration

Cover illustration: The observed X-ray diffuse scattering in the (h0l) section of 1,3-dibromo-2,5-diethyl-4,6-dimethylbenzene. Courtesy of T. R. Welberry and B. D. Butler.

research papers

J. Appl. Cryst. (1995). 28, 69-77
doi: 10.1107/S0021889894008812
link to html
An approximation is found for the number of reflections for trajectories that are transmitted by a cylindrical channel illuminated by a beam with a square angular divergence from a rectangular neutron guide. The results are compared with those for a numerical simulation.

J. Appl. Cryst. (1995). 28, 78-85
doi: 10.1107/S0021889894009222
link to html
The gyration components of ammonium Rochelle salt are measured using a universal polarimeter. The dispersion of the gyration is given over the wavelength range 350-650 nm.

J. Appl. Cryst. (1995). 28, 86-95
doi: 10.1107/S0021889894009696
link to html
A new procedure is described for the integration of diffraction peaks on imaging plates. The new `seed-skewness' method is shown to lead to more reliable intensities, especially for the weaker reflections.

J. Appl. Cryst. (1995). 28, 96-104
doi: 10.1107/S0021889894009714
link to html
The crystal structure of an approximant quasicrystal with a giant unit cell is refined.

J. Appl. Cryst. (1995). 28, 105-114
doi: 10.1107/S0021889894010095
link to html
Numerical and analytical methods are used for determining the resolution function for small-angle neutron scattering. Effects of beam-stop shadowing are also considered.

J. Appl. Cryst. (1995). 28, 115-120
doi: 10.1107/S002188989401037X
link to html
A Rietveld X-ray analysis is developed where the background scattering is described with equations based on physical principles.

J. Appl. Cryst. (1995). 28, 121-126
doi: 10.1107/S0021889894010381
link to html
The degree of crystallinity in semicrystalline materials has been determined with a Rietveld analysis with an internal approach based on Rietveld's method.

J. Appl. Cryst. (1995). 28, 127-140
doi: 10.1107/S0021889894010629
link to html
A preferred-orientation analysis for powder diffraction data is proposed based on an extension of the Wilson-plot intensity analysis in order to correct integrated intensities for structure determination.

J. Appl. Cryst. (1995). 28, 141-145
doi: 10.1107/S0021889894010113
link to html
The structure refinement and estimation of various models of vacancy ordering in γ-Fe2O3 were performed. Attention is paid to the superstructure orientation with respect to well developed planes of microcrystals that depend on the precursor.

J. Appl. Cryst. (1995). 28, 146-159
doi: 10.1107/S0021889894009027
link to html
The method described, based on the `column-like' crystal model, can be applied to both single-and multiple-order reflections. The experimental diffraction peak is fitted by a sum of elementary components represented by interference functions.

J. Appl. Cryst. (1995). 28, 160-167
doi: 10.1107/S0021889894010071
link to html
An analytical approximation is derived for easy calculation of the X-ray reflectivity pattern in low-reflectance multilayers. It allows the identification of pattern features most sensitive to certain structural parameters (average layer thicknesses and external and internal roughness).

J. Appl. Cryst. (1995). 28, 168-188
doi: 10.1107/S0021889894010083
link to html
X-ray topographic methods are used to examine the influence of the paraelectric-to-ferroelectric phase transformation on the crystal perfection of single crystals of ammonium sulfate.

J. Appl. Cryst. (1995). 28, 189-195
doi: 10.1107/S0021889894010149
link to html
X-ray scattering intensities of the primary alcohols were measured with transmission and reflection methods. The radial distribution functions were calculated and a fitting procedure was used to obtain individual atomic distances and coordination numbers.

J. Appl. Cryst. (1995). 28, 196-205
doi: 10.1107/S0021889894007867
link to html
An efficient two-dimensional X-ray detector based on direct imaging of an X-ray-sensitive phosphor with a high-resolution (1024 × 1024) charge-coupled device (CCD) array has been constructed and characterized. High detective quantum efficiency is obtained without an intensification stage.

J. Appl. Cryst. (1995). 28, 206-208
doi: 10.1107/S0021889894011015
link to html
Yttria-tetragonal zirconia polycrystal (Y-TZP), which has sometimes been assumed to be single-phase tetragonal, is shown to contain substantial (10-20%) quantities of cubic zirconia as the phase diagram predicts. The conclusions from previous studies have been examined in the light of this result.

J. Appl. Cryst. (1995). 28, 209-222
doi: 10.1107/S0021889894010617
link to html
An analytical calculation of the three-dimensional resolution function for a small-angle neutron scattering set-up has been performed by application of phase-space analysis and Gaussian approximations.

teaching and education

J. Appl. Cryst. (1995). 28, 223
doi: 10.1107/S0021889894010137
link to html
A rigorous proof of restrictions on rotation, inversion and roto-reflection axes in crystals in three dimensions is presented using transformation matrices, also that the traces of similar matrices are identical.

short communications

J. Appl. Cryst. (1995). 28, 224-225
doi: 10.1107/S0021889894010125
link to html
A device is described that is useful for the recovery and re-exposure of frozen crystals and for data collection from frozen crystals at different orientations.

computer programs

J. Appl. Cryst. (1995). 28, 225-227
doi: 10.1107/S002188989401277X
link to html
A brief description of a 3D graphics simulation program for single-crystal diffractometry is presented. The program displays both χ- and κ-type diffractometers with a zero-dimensional (conventional) counter or a two-dimensional area detector and simulates the process of data collection.

J. Appl. Cryst. (1995). 28, 228-236
doi: 10.1107/S002188989400991X
link to html
LAUEGEN is an X-windows-based program for carrying out the initial data-processing stages for Laue X-ray diffraction data. It has facilities for Laue simulations, image display and crystal orientation determination and refinement.

J. Appl. Cryst. (1995). 28, 236-242
doi: 10.1107/S0021889894009908
link to html
XDL_VIEW is an easy-to-use X-windows-based toolkit for crystallographic and more general applications. It has interfaces for both Fortran and C.

laboratory notes

J. Appl. Cryst. (1995). 28, 242-243
doi: 10.1107/S0021889894011891
link to html
A simple innovation that allows convenient parallel crystallization trials of multiple samples using hanging drops is described.

J. Appl. Cryst. (1995). 28, 243
doi: 10.1107/S0021889894012653
link to html
A modification to a standard X-ray beam tunnel that eliminates absorption of X-rays by air is described.

computer program abstracts

J. Appl. Cryst. (1995). 28, 244
doi: 10.1107/S0021889894013397
link to html
FHKL is a menu-driven X-windows program to compute structure factors, dielectric susceptibilities, absorption coefficients and crystal rocking curves, taking into account dispersion corrections, thermal agitation and polarization.

J. Appl. Cryst. (1995). 28, 244-245
doi: 10.1107/S0021889894014172
link to html
The program BREADTH calculates coherent domain sizes and lattice strains according to the `simplified' and `double-Voigt' integral-breadth methods.


J. Appl. Cryst. (1995). 28, 245-246
doi: 10.1107/S0021889895000999

new commercial products

J. Appl. Cryst. (1995). 28, 246
doi: 10.1107/S0021889895099626

books received

Follow J. Appl. Cryst.
Sign up for e-alerts
Follow J. Appl. Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds