Journal of Applied Crystallography

Volume 31, Part 2 (April 1998)


Cover illustration Cover illustration: Powder diffraction pattern of LaB6 obtained using a 200 x 400 mm flat imaging plate mounted at an angle of 45 degrees with the incoming X-ray beam. Experimental conditions: lambda = 0.8884 angstroms, D0 = 104 mm, exposure time 60 s. Courtesy of Poul Norby.

research papers



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J. Appl. Cryst. (1998). 31, 113-120    [doi:10.1107/S0021889897006560]

Determination of the Deformation State of (Zn,Mn)Se/ZnSe Multilayers

P. Schäfer, H. D. Le Thi and R. Köhler

Synopsis: A method is presented that links the measured peak separations in X-ray rocking curves to the strain tensor of the epilayer. Different critical thicknesses for the relaxation in the [110] and [110] directions are determined for (Zn,Mn)Se on ZnSe buffer on GeAs substrate.



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J. Appl. Cryst. (1998). 31, 121-127    [doi:10.1107/S0021889897006936]

An Easy Method for the Determination of Debye Temperature from Thermal Expansion Analyses

F. Sayetat, P. Fertey and M. Kessler

Synopsis: The phonon contributions to the thermal expansion of solid crystals are studied. The Debye temperature and the values of the lattice parameters exptrapolated to 0 K are determined so that extra contributions (electronic or magnetic) are displayed.



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J. Appl. Cryst. (1998). 31, 128-135    [doi:10.1107/S0021889897007802]

On the Analysis of Reversible Light-Induced Changes in Molecular Crystals

Y. Ozawa, M. R. Pressprich and P. Coppens

Synopsis: Methods and algorithms are described for the measurement and analysis of the response of crystals to irradiation by pulsed laser light. They are tested in a 40 K study of the 2.44 ms lifetime excited state of [RhBr2(pyridine-d5)]Br.



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J. Appl. Cryst. (1998). 31, 136-148    [doi:10.1107/S002188989700825X]

The Ill-Posedness of the Inverse Problem of Texture Goniometry: the Variation Width of Feasible Orientation Density Functions Revisited

H. Schaeben, H. Siemes and J.-J. Fundenberger

Synopsis: Considering the forward problem of deriving and evaluating pole density functions from given crystallographic orientation density functions, it is shown that the corresponding inverse problem is mathematically ill posed. Very different orientation density functions, differing in both even and odd terms of their harmonic series expansion, result in very similar pole density functions.



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J. Appl. Cryst. (1998). 31, 149-153    [doi:10.1107/S0021889897008789]

On the Retrieval of Particle Size Distributions from Small-Angle Scattering Data: the Influence of Statistical Data Dispersion

M. Mulato, D. Tygel and I. Chambouleyron

Synopsis: The problem of the retrieval of the particle size distribution of scatterers from small-angle scattering experiments with noisy data is addressed.



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J. Appl. Cryst. (1998). 31, 154-162    [doi:10.1107/S0021889897008868]

Diffuse X-ray Scattering and Short-Range Order in Thallium Antimonyl Germanate, TlSbOGeO4

T. R. Welberry and S. C. Mayo

Synopsis: Diffuse scattering has been recorded for the KTP analogue material TlSbOGeO4, and a preliminary interpretation made using Monte Carlo simulation. The diffuse scattering originates predominantly from the disorder of the thallium cations between alternative sites Tl and Tl', and the occupancy of these sites tends to alternate along the b crystal direction.



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J. Appl. Cryst. (1998). 31, 163-168    [doi:10.1107/S002188989700900X]

Extinction and Grain-Size Anisotropy Correction of Texture Data Obtained Using Neutron Diffraction

M. Birsan and J. A. Szpunar

Synopsis: When neutron diffraction is used, texture measurements are affected by extinction and anisotropy of grain size. A method of correction is proposed and tested.



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J. Appl. Cryst. (1998). 31, 169-175    [doi:10.1107/S0021889897009084]

Diffuse Scattering Investigations with a Graphite Double Monochromator for X-ray Synchrotron Radiation: YBa2Cu3O6.5 and KNbO3

E. Straube, D. Hohlwein and Th. Zeiske

Synopsis: A graphite double monochromator has been built and tested. With a Weissenberg camera and an image plate, diffuse superstructure reflections and diffuse planes have been recorded.



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J. Appl. Cryst. (1998). 31, 176-180    [doi:10.1107/S0021889897009795]

The (hkl) Dependence of Diffraction-Line Broadening Caused by Strain and Size for all Laue Groups in Rietveld Refinement

N. C. Popa

Synopsis: Models for the anisotropic broadening of the Bragg peaks caused by microstrain and crystallite size are derived for all Laue groups. The models are suitable for implementation in the Rietveld refinement programs.



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J. Appl. Cryst. (1998). 31, 181-184    [doi:10.1107/S002188989700928X]

In Situ Fixed-Angle X-ray Reflectivity Measurement of Thin-Film Roughness and Thickness during Deposition

C.-H. Lee and S.-Y. Tseng

Synopsis: An oscillating reflective intensity was measured with the sample and detector at fixed specular angles during the thin-film growth. This oscillating intensity carries the information of thin-film thickness and roughness.



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J. Appl. Cryst. (1998). 31, 185-197    [doi:10.1107/S0021889897009643]

Diffractometer Noise Characteristics: Experimental Determination and Application to Statistical Rocking-Curve Analysis

T. W. Staley and R. J. Matyi

Synopsis: This paper examines the dependence of experimental noise in an X-ray rocking curve and develops a procedure for the use of this noise characteristic as a weight function for the optimization and analysis of calculated fits of the rocking curve.



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J. Appl. Cryst. (1998). 31, 198-203    [doi:10.1107/S0021889897009990]

A (2+3)-Type Surface Diffractometer: Mergence of the z-Axis and (2+2)-Type Geometries

E. Vlieg

Synopsis: The addition of an azimuthal detector rotation to a (2+2)-type diffractometer makes it fully equivalent to a z-axis type. The geometric correction factors for this (2+3)-type diffractometer, which are needed to obtain structure factors from measured integrated intensities, are derived.



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J. Appl. Cryst. (1998). 31, 204-211    [doi:10.1107/S0021889897010005]

Minimum-Angle versus Low-Index Axis Rotations for Representing Small- and Large-Angle Grain Boundary Misorientations in Cubic Lattices

S. Gourdet, J. J. Jonas and F. Montheillet

Synopsis: Some new properties of the least-angle rotation between two cubic crystals are derived. The extent to which a misorientation may alternatively be described by some low-index axis rotation is also examined.



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J. Appl. Cryst. (1998). 31, 212-222    [doi:10.1107/S002188989701011X]

Nanoscale Hardening Precipitiation in AlMgSi Alloys: A Transmission Electron Microscopy and Small-Angle Neutron Scattering Study

P. Donnadieu, F. Carsughi, A. Redjaimia, C. Diot and G. Lapasset

Synopsis: Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) have been used to study hardening precipitation in a 6056 Al-Mg-Cu-Si alloy at peak ageing. TEM gives the precipitate morphology and structure while the SANS data analysis yields their distribution and mean size.



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J. Appl. Cryst. (1998). 31, 223-234    [doi:10.1107/S0021889897011771]

Neutron Storage in a Longitudinally Vibrating Silicon Crystal

R. Hock, K. D. Liss, A. Magerl, O. G. Randl and A. Remhof

Synopsis: The storage of cold neutrons in a longitudinally vibrating silicon crystal is demonstrated by time-resolved transmission experiments on a high-resolution backscattering spectrometer. The experimental results are compared with Monte Carlo simulations.



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J. Appl. Cryst. (1998). 31, 235-240    [doi:10.1107/S0021889897014581]

Surface-Induced Parasitic Scattering in Bonse-Hart Double-Crystal Diffractometers

M. Agamalian, D. K. Christen, A. R. Drews, C. J. Glinka, H. Matsuoka and G. D. Wignall

Synopsis: Surface-induced scattering from Si(111) crystal has been studied and attributed to the network of cracks produced by cutting. This scattering can be significantly reduced by deep etching of the crystal.



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J. Appl. Cryst. (1998). 31, 241-251    [doi:10.1107/S0021889897009096]

Extended Kinematic Approach to the Simulation of High-Resolution X-ray Diffraction Spectra. Application to Structures with Buried Amorphous Layers

E. Zolotoyabko

Synopsis: A new approach to the simulation of high-resolution X-ray diffraction spectra is developed using direct summation of scattered waves. The simulation procedure permits the introduction of short-range variations of structural and geometrical parameters of multilayered systems.


cryocrystallography papers



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J. Appl. Cryst. (1998). 31, 252-257    [doi:10.1107/S0021889897009229]

Cooling Rates During Flash Cooling

T.-Y. Teng and K. Moffat

Synopsis: Measurements of cooling rates were made for different cryoprotectants with different sample volumes and cooling agents. Approaches by which the increase in mosaic spread during flash cooling of macromolecular crystals might be minimized are discussed.


short communications



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J. Appl. Cryst. (1998). 31, 258-261    [doi:10.1107/S0021889897011795]

On the divergence of rays Bragg diffracted by perfect stationary crystals illuminated with collimated polychromatic radiation

A. R. Lang

Synopsis: Among the various diffraction geometries possible with the incident illumination specified, symmetric Bragg-case reflection has the valuable special property of invariant direction of reflected rays, independent of wavelength and the extinction distance of the reflection.


computer programs



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J. Appl. Cryst. (1998). 31, 262-269    [doi:10.1107/S002188989700811X]

BEARTEX: a Windows-based program system for quantitative texture analysis

H.-R. Wenk, S. Matthies, J. Donovan and D. Chateigner

Synopsis: This report introduces a software package for quantitative texture analysis, applicable to all crystal symmetries. The 20 computer programs provide for processing of experimental data, calculation of the orientation distribution and anisotropic properties as well as various graphic representations.



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J. Appl. Cryst. (1998). 31, 270-274    [doi:10.1107/S0021889897013253]

Automated and graphical methods for locating heavy-atom sites for isomorphous replacement and multiwavelength anomalous diffraction phase determination

J. Badger and R. Athay

Synopsis: A new program for automatically determining heavy-atom derivative sites from SIR data and anomalous-scatterer sites from MAD-FA coefficients is described. The program is deployed with a set of interactive graphical tools for checking and editing the heavy-atom sites against difference Patterson and cross-difference Fourier maps.



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J. Appl. Cryst. (1998). 31, 275-277    [doi:10.1107/S0021889897010558]

Program to generate and evaluate three-phase structure-invariant [omega] estimates from single-wavelength anomalous dispersion data

D. A. Langs

Synopsis: A direct-methods computer program to evaluate Hauptmann's three-phase triple-invariant estimates for single-wavelength anomalous dispersion data is described.


cif applications



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J. Appl. Cryst. (1998). 31, 278-281    [doi:10.1107/S0021889897007280]

CIF Applications. VII. CYCLOPS2: extending the validation of CIF data names

H. J. Bernstein and S. R. Hall

Synopsis: CYCLOPS2 is a major revision of the program CYCLOPS, which is used, in conjunction with Crystallographic Information File (CIF) dictionaries, to validate names in an ASCII file.



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J. Appl. Cryst. (1998). 31, 282-295    [doi:10.1107/S0021889897007309]

CIF Applications. VIII. pdb2cif: translating PDB entries into mmCIF format

H. J. Bernstein, F. C. Bernstein and P. E. Bourne

Synopsis: pdb2cif is a new version of an awk script originally written by P. E. Bourne in 1993 to translate from the 1992 Protein data Bank (PDB) format to the macromolecular Crystallographic Information File (mmCIF) definition. This new version of pdb2cif translates all current PDB formats.


laboratory notes



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J. Appl. Cryst. (1998). 31, 296-298    [doi:10.1107/S0021889897009199]

A device for low-temperature crystal reorientation in data collection with the oscillation method

A. Darovsky and P. Coppens

Synopsis: A device that allows reorientation of a crystal at low temperature, without remounting or warming to ambient temperature, is described.



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J. Appl. Cryst. (1998). 31, 299-301    [doi:10.1107/S002188989701056X]

A high-transmission furnace insert for neutron powder diffraction studies at high temperatures under a pressurized reactive atmosphere

J. A. Rollings, D. C. Tennant and I. P. Swainson

Synopsis: A new furnace insert has been devised in which a sample can be studied using neutron scattering techniques in situ under several atmospheres of gas pressure and temperatures up to 1350 K.


fast communications



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J. Appl. Cryst. (1998). 31, 302-304    [doi:10.1107/S0021889897018062]

On the correction of reflection intensities recorded on imaging plates for incomplete absorption in the phosphor layer.

J. Zaleski, G. Wu and P. Coppens

Synopsis: The use of imaging plates as detectors in X-ray crystallography requires a correction for oblique incidence of the diffracted beam on the plate. The correction becomes important for wavelengths less than about 1 Å.



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J. Appl. Cryst. (1998). 31, 305-307    [doi:10.1107/S0021889898002714]

Moving median filters for area-detector data

J. H. Reibenspies

Synopsis: Moving median filters have been employed to remove impulse noise from two-dimensional area-detector data. The median filters are compared to generalized moving mean filters.


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