Journal of Applied Crystallography

Volume 32, Part 3 (June 1999)



[Issue Author Index][Volume Author Index]
[Cover illustration] Cover illustration: Simulated diffraction pattern for a two-dimensionally disordered decasil (porous SiO2) calculated using a fast recursive algorithm. The plane is perpendicular to c with the reciprocal index l = 1; the error probability is 0.5 and the intensities are scaled to 25% of the highest value. Courtesy of Peter Daniels.

research papers


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J. Appl. Cryst. (1999). 32, 381-386  [ doi:10.1107/S0021889898012898 ]

A standardless method of quantitative ceramic analysis using X-ray powder diffraction

S. Mazumdar

Synopsis: A procedure for quantitative estimation of crystalline/amorphous phases in ceramics is described. The method does not require calibration data for use as an internal/external standard.

Online June 1999


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J. Appl. Cryst. (1999). 32, 387-392  [ doi:10.1107/S0021889898012990 ]

X-ray diffraction texture analysis of cylindrical samples

R. Guillén, C. Cossu, T. Jacquot, M. François and B. Bourniquel

Synopsis: A theoretical model, based on a ray-tracing method, has been developed to take into account the effect of curvature of cylindrical samples on the X-ray diffraction peak intensities. Texture analysis of zircaloy-4 tubes (9.5  mm diameter) confirms the validity of the model.

Online June 1999


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J. Appl. Cryst. (1999). 32, 393-396  [ doi:10.1107/S0021889898015064 ]

Texture and residual-stress analysis using a kappa goniometer

R. Guillén, M. François, B. Bourniquel and E. Girard

Synopsis: A reliable and relatively inexpensive kappa goniometer has been constructed to perform texture and residual-stress analysis in both [Omega] and [chi] configurations. Validation has been achieved by checking the setting precision and the assembly reliability for the two types of configuration.

Online June 1999


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J. Appl. Cryst. (1999). 32, 397-403  [ doi:10.1107/S0021889898014290 ]

Nanoscopic unequivocal analysis of twinned crystal structures with tetragonal or orthogonal unit cells by electron microdiffraction

M. Leicht, T. Remmele, D. Stenkamp and H. P. Strunk

Synopsis: A twin structure in chalcogenides characterized by a tetragonal unit cell, lattice-parameter ratio c/a = 2 and twin-habit plane {102} is identified by electron microdiffraction at a transmission electron microscope. The analysis represents a method to analyse unambiguously electron diffraction patterns for reliable electron crystallography in nanoscopic volumes.

Online June 1999


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J. Appl. Cryst. (1999). 32, 404-408  [ doi:10.1107/S0021889898015271 ]

Natural partitioning of orientation elements and determination of the ODF from individual orientations according to the maximum-entropy principle

Y. D. Wang, A. Vadon, J. Bessières and J. J. Heizmann

Synopsis: A new method for the determination of the orientation distribution function (ODF) from individual orientations is proposed.

Online June 1999


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J. Appl. Cryst. (1999). 32, 409-412  [ doi:10.1107/S0021889898015532 ]

A real-space approach to the solution of a disordered structure of the three-dimensional coordination polymer Fe(CN)6[Sn(C4H9)3]3

X. Wang, Y.-S. Chen and W.-P. Su

Synopsis: A new real-space approach to the X-ray phase problem is applied to solve a disordered structure of a three-dimensional coordination polymer.

Online June 1999


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J. Appl. Cryst. (1999). 32, 413-416  [ doi:10.1107/S0021889898015763 ]

Determination of symmetries and idealized cell parameters for simulated structures

R. Hundt, J. C. Schon, A. Hannemann and M. Jansen

Synopsis: A robust algorithm is described for the determination of symmetries in an atomic configuration.

Online June 1999


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J. Appl. Cryst. (1999). 32, 417-420  [ doi:10.1107/S0021889898015817 ]

The structure of approximant [mu]-Al4Mn interpreted as a modulated crystal

M. Uchida and S. Horiuchi

Synopsis: The structure of the [mu]-Al4Mn phase is interpreted as a modulated crystal structure. The modulation is considered to be due to the rearrangement of atomic vacancies as a response to the occurrence of charge-density waves.

Online June 1999


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J. Appl. Cryst. (1999). 32, 421-425  [ doi:10.1107/S0021889898016501 ]

K2(NbO)2Si4O12: a new ferroelectric

M. C. Foster, D. J. Arbogast, P. Photinos, R. M. Nielson and S. C. Abrahams

Synopsis: K2(NbO)2Si4O12 satisfies the structural criteria for ferroelectricity and has an estimated Curie temperature higher than its melting point of 1476  K. The demonstration of dielectric hysteresis under both direct and alternating current, with a spontaneous polarization of about 0.2  C  m-2, provides unambiguous verification of the predicted ferroelectricity.

Online June 1999


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J. Appl. Cryst. (1999). 32, 426-435  [ doi:10.1107/S0021889898017282 ]

An improved small-angle X-ray scattering analysis of [delta]' precipitation in an Al-Li alloy for growth kinetic studies

C.-S. Tsao and T.-L. Lin

Synopsis: An improved SAXS method of analysis is examined and used to study the kinetic model of the late stage of [delta]' precipitation in an Al-Li alloy by analysing the simulated and measured SAXS data.

Online June 1999


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J. Appl. Cryst. (1999). 32, 436-441  [ doi:10.1107/S0021889898017233 ]

Ab initio structure determination of sulfathiazole polymorph V from synchrotron X-ray powder diffraction data

F. C. Chan, J. Anwar, R. Cernik, P. Barnes and R. M. Wilson

Synopsis: The crystal structure of sulfathiazole polymorph V has been determined ab initio from synchrotron powder diffraction data using direct methods. With 17 non-H atoms in the molecule and two molecules in the asymmetric unit, the structure represents the highest complexity organic structure solved to date from powder data.

Online June 1999


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J. Appl. Cryst. (1999). 32, 442-451  [ doi:10.1107/S0021889898017725 ]

Exploring reciprocal space of a quasicrystal by means of an imaging plate

M. Kopecky and R. Colella

Synopsis: A monochromatic Laue technique is used to extract information about the reciprocal lattice of a quasicrystal. A synchrotron beamline, normally available for protein crystallography, was used in this study.

Online June 1999


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J. Appl. Cryst. (1999). 32, 452-455  [ doi:10.1107/S0021889898018378 ]

Extension of three-dimensional space-group generators to the (3+1) case

K. Stróz

Synopsis: A method of building up the generators of 775 (3+1)-dimensional superspace groups from the conventional space group generators is presented.

Online June 1999


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J. Appl. Cryst. (1999). 32, 456-463  [ doi:10.1107/S0021889898018469 ]

Application of silver behenate powder for wavelength calibration of a SANS instrument - a comprehensive study of experimental setup variations and data processing techniques

U. Keiderling, R. Gilles and A. Wiedenmann

Synopsis: The wavelength calibration procedure of a small-angle neutron scattering (SANS) instrument using Bragg reflections from silver behenate powder is extensively demonstrated, and compared with the calibration procedure using time-of-flight measurements.

Online June 1999


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J. Appl. Cryst. (1999). 32, 464-471  [ doi:10.1107/S0021889898018470 ]

Diffuse scattering and Monte Carlo simulations of cyclohexane-perhydrotriphenylene (PHTP) inclusion compounds, C6H12/C18H30

S. C. Mayo, T. Proffen, M. Bown and T. R. Welberry

Synopsis: A recently developed method for fitting a Monte Carlo computer simulation model to observed single-crystal diffuse X-ray scattering has been applied to (hk0) scattering data obtained for the guest-host system (inclusion compound) cyclohexane-perhydrotriphenylene at 295  K. A simple two-dimensional model representing the projection of the structure down c was used, which allowed refinement of short-range order parameters describing the mutual orientation of guest molecules within neighbouring channels, together with a parameter describing the coupling of these orientations to distortions of the host framework.

Online June 1999


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J. Appl. Cryst. (1999). 32, 472-474  [ doi:10.1107/S002188989900165X ]

Application of the molecular replacement method to a heavy-atom problem

J. G. Arnez

Synopsis: The molecular replacement method has been applied in a case for which a heavy-atom model existed for one crystal form, and both native and derivative data were available for another crystal form of the same molecule.

Online June 1999


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J. Appl. Cryst. (1999). 32, 475-480  [ doi:10.1107/S0021889899002344 ]

Stabilization of cubic Na-modified ZrO2: a neutron diffraction study

P. Canton, G. Fagherazzi, R. Frattini and P. Riello

Synopsis: Neutron diffraction on an Na-modified ZrO2 showed the presence of both cubic plus tetragonal phases, the tetragonal phase being almost undetectable by X-ray diffraction.

Online June 1999


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J. Appl. Cryst. (1999). 32, 481-488  [ doi:10.1107/S0021889899002423 ]

Isomorphism and mixed crystals in 2-R-naphthalenes: evidence of structural subfamilies and prediction of metastable forms

Y. Haget, N. B. Chanh, A. Meresse, L. Bonpunt, F. Michaud, P. Negrier, M. A. Cuevas-Diarte and H. A. J. Oonk

Synopsis: The variations of the unit-cell parameters measured as a function of composition for a number of binary systems of the series of 2-R-naphthalenes are shown to be consistent with the division of the series into two structural subfamilies, corresponding to two slightly different types of packing in crystals of the high-temperature form.

Online June 1999


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J. Appl. Cryst. (1999). 32, 489-496  [ doi:10.1107/S002188989900240X ]

Contrast in X-ray section topographs of perfect silicon crystals using the Laue-Laue three-beam case of diffraction

F. Heyroth, H.-R. Höche and C. Eisenschmidt

Synopsis: Section topographs taken in three-beam diffraction geometry and in the neighbourhood of this geometric position are presented. They show new contrast phenomena which are discussed in terms of the dynamical diffraction theory, the effective structure factor and the dispersion surface.

Online June 1999


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J. Appl. Cryst. (1999). 32, 497-504  [ doi:10.1107/S0021889899002411 ]

Adaptation of the Rietveld method to the characterization of the lamellar microstructure of polymers. 2. Influence of a tilt of chain axes versus the normal to basal planes of crystalline lamellae

O. Dupont, D. A. Ivanov, A. M. Jonas and R. Legras

Synopsis: The possibility of determining the dimensions of lamellar crystals and the angle between chain axes and lamellar surfaces from X-ray powder diffractometry performed on semicrystalline polymers, using a variant of Rietveld method, is assessed.

Online June 1999


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J. Appl. Cryst. (1999). 32, 505-509  [ doi:10.1107/S0021889899002678 ]

A method to stabilize reduced and/or gas-treated protein crystals by flash-cooling under a controlled atmosphere

X. Vernède and J. C. Fontecilla-Camps

Synopsis: A customized glove box for protein crystallization under a controlled atmosphere is described along with a cryogenic technique adapted to flash-cool crystals inside the glove box and a device for studying gas-protein complexes in crystals at cryogenic temperatures.

Online June 1999


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J. Appl. Cryst. (1999). 32, 510-515  [ doi:10.1107/S0021889899002721 ]

Diffractometric crystal centering

P. Dera and A. Katrusiak

Synopsis: A general formalism for centering a single-crystal on a four-circle diffractometer, based on the setting angles of reflections, is presented.

Online June 1999


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J. Appl. Cryst. (1999). 32, 516-524  [ doi:10.1107/S0021889899002939 ]

Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image

X. R. Huang, M. Dudley, W. M. Vetter, W. Huang, W. Si and C. H. Carter Jr

Synopsis: A geometrical diffraction simulation model is developed to provide understanding of direct dislocation images on synchrotron white-beam X-ray topographs, and is successfully applied to illustrate the contrast formation mechanisms involved in images of superscrew dislocations in silicon carbide crystals.

Online June 1999


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J. Appl. Cryst. (1999). 32, 525-529  [ doi:10.1107/S0021889899003192 ]

An elastically bent silicon monochromator for a neutron diffractometer

I. Tanaka, N. Niimura and P. Mikula

Synopsis: A new type of elastically bent perfect Si (EBP-Si) monochromator for a neutron diffractometer dedicated to protein crystallography has been developed and its distinctive features are summarized.

Online June 1999


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J. Appl. Cryst. (1999). 32, 530-535  [ doi:10.1107/S0021889899003209 ]

Positioning a protein molecule in the asymmetric unit using very low order reflections and packing restraints

K. M. Andersson

Synopsis: A translation and packing algorithm, using a spherical model, for positioning a protein molecule in the asymmetric unit using about ten of the lowest order reflections has been applied to a number of protein structures. The packing algorithm is used to check if the positions determined from the translation search are within the allowable packing regions. The calculated phases for these reflections are in excellent agreement with the true phases calculated from the entire protein.

Online June 1999


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J. Appl. Cryst. (1999). 32, 536-542  [ doi:10.1107/S0021889899003453 ]

Zeolite structure determination from powder diffraction data: applications of the FOCUS method

R. W. Grosse-Kunstleve, L. B. McCusker and C. Baerlocher

Synopsis: The FOCUS approach to zeolite structure determination from powder diffraction data has been applied to data from four different zeolitic materials. Taken together, the four examples give an overview of the practical aspects of the FOCUS method and illustrate its potential and its limitations.

Online June 1999


short communications


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J. Appl. Cryst. (1999). 32, 543-545  [ doi:10.1107/S0021889899000990 ]

An improved low-power-consumption heating stage for X-ray powder diffraction

G. Valdrè

Synopsis: An easy-to-operate simple heating stage with very low power consumption for use in an X-ray powder diffractometer is described and discussed. The stage allowed the study of structural transformations with temperature and was successfully used for the characterization of very different materials, such as hyaloclastite, montmorillonites, various smectites and chlorocadmates with perovskite-like structures.

Online June 1999


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J. Appl. Cryst. (1999). 32, 546-548  [ doi:10.1107/S0021889899002071 ]

Size distribution of single-crystal nanoparticles by Monte Carlo fitting of wide-angle X-ray scattering peak shape

P. E. Di Nunzio and S. Martelli

Synopsis: Particle size distribtions determined by a Monte Carlo algorithm for X-ray peak shape cutting are compared with those directly observed by transmission electron microscopy. The X-ray diffraction technique can be confidently used for particle dimensions below about 60  nm.

Online June 1999


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J. Appl. Cryst. (1999). 32, 549-550  [ doi:10.1107/S002188989900271X ]

X-ray diffraction in disordered paraelectric crystal structures with polar clusters and the g parameter

K. Lukaszewicz

Synopsis: As a result of the peculiar features of X-ray diffraction in disordered structures, additional information on the range of order can be obtained by introducing the g parameter into the structure-factor equation.

Online June 1999


computer programs


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J. Appl. Cryst. (1999). 32, 551-553  [ doi:10.1107/S0021889898013375 ]

CPRL: a program to plot the cylindrically projected reciprocal lattice for fiber diffraction patterns

V. L. Finkenstadt, J. L. van der Plas and R. P. Millane

Synopsis: The program CPRL plots the positions of reflections on diffraction patterns from complex polycrystalline fibers. The results from the program are useful for interpreting fiber diffraction patterns from complex systems.

Online June 1999


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J. Appl. Cryst. (1999). 32, 554-562  [ doi:10.1107/S0021889898015350 ]

LSCALE - the new normalization, scaling and absorption correction program in the Daresbury Laue software suite

S. Arzt, J. W. Campbell, M. M. Harding, Q. Hao and J. R. Helliwell

Synopsis: LSCALE, a new program in the Daresbury Laue software suite, includes the derivation and application of an absorption correction, not previously available in any Laue package, and an improved wavelength normalization procedure. Both procedures require redundancy of observations in the Laue data set.

Online June 1999


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J. Appl. Cryst. (1999). 32, 563-571  [ doi:10.1107/S0021889899002666 ]

Modeling hydroxyl and water H atoms

M. Nardelli

Synopsis: The coordinates of hydroxyl and water H atoms are obtained by combined geometric and force-field calculations.

Online June 1999


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J. Appl. Cryst. (1999). 32, 572-575  [ doi:10.1107/S0021889899003532 ]

PDFFIT, a program for full profile structural refinement of the atomic pair distribution function

T. Proffen and S. J. L. Billinge

Synopsis: PDFFIT is a program for the full profile structural refinement of the atomic pair distribution function. Structural parameters such as atomic positions, anisotropic temperature factors and occupancies can be refined. The program is controlled by a powerful command language and allows the simultaneous refinement of multiple data sets and/or multiple structural phases.

Online June 1999


laboratory notes


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J. Appl. Cryst. (1999). 32, 576-578  [ doi:10.1107/S002188989801406X ]

A hinge goniometer head

A. Katrusiak

Synopsis: A stable lightweight goniometer head for mounting heavy crystal-environment attachments on diffractometers has been designed.

Online June 1999


J. Appl. Cryst.. (1999). 32, 0

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