Journal of Applied Crystallography

Volume 28, Part 2 (April 1995)

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
• teaching and education in crystallography
• short communications
• computer programs
• laboratory notes
• computer program abstracts
• crystallographers
• new commercial products
• books received

research papers

J. Appl. Cryst. (1995). 28, 69-77    [doi:10.1107/S0021889894008812]

The Number of Reflections of a Neutron Beam Transmitted by a Capillary Fiber

D. F. R. Mildner, V. A. Sharov and H. Chen

Synopsis: 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]

Determination of the Gyration Tensor Components of Ammonium Rochelle Salt

Z. Brozek, K. Stadnicka, R. J. Lingard and A. M. Glazer

Synopsis: 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]

The `Seed-Skewness' Method for Integration of Peaks on Imaging Plates

R. Bolotovsky, M. A. White, A. Darovsky and P. Coppens

Synopsis: 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]

Structural Study of Crystalline Approximants of the Al-Cu-Fe-Cr Decagonal Quasicrystal

X. Z. Li, C. Dong and J. M. Dubois

Synopsis: 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]

Instrumental Smearing Effects in Radially Symmetric Small-Angle Neutron Scattering by Numerical and Analytical Methods

J. G. Barker and J. S. Pedersen

Synopsis: 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]

X-ray Rietveld Analysis with a Physically Based Background

P. Riello, G. Fagherazzi, D. Clemente and P. Canton

Synopsis: 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]

Determining the Degree of Crystallinity in Semicrystalline Materials by means of the Rietveld Analysis

P. Riello, G. Fagherazzi, P. Canton, D. Clemente and M. Signoretto

Synopsis: 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]

Preferred-Orientation Correction and Normalization Procedure for Ab Initio Structure Determination from Powder Data

R. Peschar, H. Schenk and P. Capková

Synopsis: 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]

Vacancy Ordering in -Fe₂O₃: Synchrotron X-ray Powder Diffraction and High-Resolution Electron Microscopy Studies

A. N. Shmakov, G. N. Kryukova, S. V. Tsybulya, A. L. Chuvilin and L. P. Solovyeva

Synopsis: The structure refinement and estimation of various models of vacancy ordering in -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]

A Monte Carlo Estimate of Crystallite-Size and Microstrain Distribution Functions from X-ray Line Broadening

P. E. Di Nunzio, S. Martelli and R. Ricci Bitti

Synopsis: 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]

Structural Parameters of Multilayers from X-ray Reflectivity: an Easy-to-Handle Approach

M. Manciu, L. Dudas, C. Sürgers and R. Manaila

Synopsis: 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]

An X-ray Topographic Study of the Paraelectric-to-Ferroelectric Phase Transformation in Nearly Perfect Single Crystals of Ammonium Sulfate

H. L. Bhat, H. Klapper and K. J. Roberts

Synopsis: 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]

Determination of Liquid Structures of the Primary Alcohols Methanol, Ethanol, 1-Propanol, 1-Butanol and 1-Octanol by X-ray Scattering

K. S. Vahvaselkä, R. Serimaa and M. Torkkeli

Synopsis: 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]

A Large-Format High-Resolution Area X-ray Detector Based on a Fiber-Optically Bonded Charge-Coupled Device (CCD)

M. W. Tate, E. F. Eikenberry, S. L. Barna, M. E. Wall, J. L. Lowrance and S. M. Gruner

Synopsis: 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]

Re-investigation of Yttria-Tetragonal Zirconia Polycrystal (Y-TZP) by Neutron Powder Diffraction - a Cautionary Tale

D. N. Argyriou and C. J. Howard

Synopsis: 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]

The Three-Dimensional Resolution Function for Small-Angle Scattering and Laue Geometries

P. Harris, B. Lebech and J. S. Pedersen

Synopsis: 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 in crystallography

J. Appl. Cryst. (1995). 28, 223    [doi:10.1107/S0021889894010137]

Three-dimensional periodicity and inversion axes in crystals

B. D. Sharma

Synopsis: 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]

A novel device for the recovery of frozen crystals

F. Mancia, C. Oubridge, C. Hellon, T. Woollard, J. Groves and K. Nagai

Synopsis: 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]

DS - a 3D graphics simulation program for single-crystal diffractometry

C. Zheng, M. Yao and I. Tanaka

Synopsis: A brief description of a 3D graphics simulation program for single-crystal diffractometry is presented. The program displays both - and -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]

LAUEGEN, an X-windows-based program for the processing of Laue diffraction data

J. W. Campbell

Synopsis: 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]

XDL VIEW, an X-windows-based toolkit for crystallographic and other applications

J. W. Campbell

Synopsis: 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]

The multi-drop approach: more efficient screening of crystallization conditions

C. M. Bruns and P. A. Karplus

Synopsis: 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]

A helium-flushed beam tunnel

S. Parkin and B. Rupp

Synopsis: 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]

FHKL - a program to compute rocking curves and crystallographic data of interest for the dynamical theory of X-rays

A. Soyer

Synopsis: 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]

BREADTH - a program for analyzing diffraction line broadening

D. Balzar

Synopsis: The program BREADTH calculates coherent domain sizes and lattice strains according to the `simplified' and `double-Voigt' integral-breadth methods.

crystallographers

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

Crystallographers

new commercial products

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

New Commercial Products

books received

J. Appl. Cryst. (1995). 28, 246    [doi:10.1107/S0021889895099614]

Modern crystallography, Vol. 1, Fundamentals of crystals. Symmetry, and methods of structural crystallography by B. K. Vainshtein

J. Appl. Cryst. (1995). 28, 246    [doi:10.1107/S0021889895099602]

Crystallographic computing 6. A window on modern crystallography. (IUCr Crystallographic Symposia No. 6) edited by H. D. Flack, L. Párkányi and K. Simon

Copyright © International Union of Crystallography
IUCr Webmaster