Journal of Applied Crystallography

Volume 32, Part 4 (August 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, 579-589  [ doi:10.1107/S0021889899000618 ]

Direct analysis of small-angle smeared intensity tails. I. General results

S. Ciccariello and R. Sobry

Synopsis: The asymptotic leading terms of small-angle scattering smeared intensities are discussed and numerically analysed. The smeared oscillatory contributions in practice coincide with those smeared by an ideal slit.

Online August 1999


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J. Appl. Cryst. (1999). 32, 590-599  [ doi:10.1107/S0021889899002927 ]

Direct analysis of small-angle smeared intensity tails. II. Applications

S. Ciccariello and R. Sobry

Synopsis: The shape and particle sizes of two triblock copolymers are obtained from the analysis of the tails of the smeared small-angle X-ray intensities. In one of the samples, particles are found to be organized as in a dense hard-sphere fluid.

Online August 1999


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J. Appl. Cryst. (1999). 32, 600-613  [ doi:10.1107/S0021889899000692 ]

A maximum entropy method for determining column-length distributions from size-broadened X-ray diffraction profiles

N. Armstrong and W. Kalceff

Synopsis: This paper discusses the application of a twofold maximum entropy method for determining specimen profiles and crystallite size distributions, and their corresponding uncertainties, from size-broadened X-ray diffraction profiles. Simulated size-broadened profiles are used to demonstrate the application of the method.

Online August 1999


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J. Appl. Cryst. (1999). 32, 614-623  [ doi:10.1107/S0021889899001223 ]

Angle calculations for a `4S+2D' six-circle diffractometer

H. You

Synopsis: Angle calculations are derived for the operation of a `4S+2D' six-circle X-ray or neutron diffractometer. Four sample-orienting and two detector-orienting degrees of freedom are used to control the scattering vector and a reference vector in the laboratory frame of reference.

Online August 1999


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J. Appl. Cryst. (1999). 32, 624-633  [ doi:10.1107/S0021889899002393 ]

Measurement of single-crystal elastic constants by neutron diffraction from polycrystals

C. J. Howard and E. H. Kisi

Synopsis: Expressions are developed relating the diffraction elastic constants for a polycrystalline material to the single-crystal elastic constants for crystal systems with orthorhombic and higher symmetry. It is shown that these expressions may be used to extract single-crystal elastic constants from measurements on polycrystals or, alternatively, may be used to provide insight into the stress-strain state in polycrystalline samples by a comparison of measured and calculated diffraction elastic constants.

Online August 1999


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J. Appl. Cryst. (1999). 32, 634-640  [ doi:10.1107/S0021889899003222 ]

Flat-specimen effect as a convolution in powder diffractometry with Bragg-Brentano geometry

T. Ida and K. Kimura

Synopsis: Mathematical formulae of the flat-specimen effect in powder diffractometry with Bragg-Brentano geometry are examined.

Online August 1999


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J. Appl. Cryst. (1999). 32, 641-653  [ doi:10.1107/S0021889899003441 ]

Optimization of resolution-intensity balance in angular-dispersive powder diffractometry at a synchrotron radiation source

B. Grabcev and A. Tirziu

Synopsis: A unique resolution function of angular-dispersive powder diffractometers, properly parametrized to be valid for any multicrystal variant of the instrument, has been derived. A computer simulation method offers reliable information, useful for designing diffractometers and conducting experiments.

Online August 1999


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J. Appl. Cryst. (1999). 32, 654-663  [ doi:10.1107/S0021889899003428 ]

On the number of independent reflections in a powder diffraction pattern

W. I. F. David

Synopsis: The number of independent reflections in a powder diffraction pattern is derived from the eigenvalues of the integrated intensities covariance matrix obtained from a Pawley analysis.

Online August 1999


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J. Appl. Cryst. (1999). 32, 664-670  [ doi:10.1107/S0021889899003416 ]

Difference structure-factor normalization for heavy-atom or anomalous-scattering substructure determinations

R. H. Blessing and G. D. Smith

Synopsis: Procedures are described for preparing single-derivative isomorphous replacement and single-wavelength anomalous scattering difference-magnitude data for probabilistic direct-methods phasing.

Online August 1999


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J. Appl. Cryst. (1999). 32, 671-682  [ doi:10.1107/S002188989900374X ]

Fourier modelling of the anisotropic line broadening of X-ray diffraction profiles due to line and plane lattice defects

P. Scardi and M. Leoni

Synopsis: A new model of line-profile broadening due to the effect of linear and planar lattice defects has been incorporated into the conventional Rietveld algorithm for the structural refinement and whole-pattern fitting of powder data. Theory is presented along with examples of applications to face-centred cubic structures.

Online August 1999


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J. Appl. Cryst. (1999). 32, 683-691  [ doi:10.1107/S0021889899003817 ]

Deconvolution of the two-dimensional point-spread function of area detectors using the maximum-entropy algorithm

H. Graafsma and R. Y. de Vries

Synopsis: The maximum entropy algorithm is used to deconvolute the point-spread function of two-dimensional area detectors. This results in significant image enhancement.

Online August 1999


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J. Appl. Cryst. (1999). 32, 692-703  [ doi:10.1107/S0021889899002861 ]

Simulations of femtosecond X-ray diffraction from unperturbed and rapidly heated single crystals

J. S. Wark and R. W. Lee

Synopsis: Simulations are presented of the dynamical diffraction of femtosecond pulses of X-rays from crystals whose structures are modified on similar time scales. Such simulations are of relevance to experiments in which short pulses of X-rays from synchrotron or laser sources are diffracted from rapidly laser-heated crystals.

Online August 1999


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J. Appl. Cryst. (1999). 32, 704-715  [ doi:10.1107/S0021889899004215 ]

Quantitative phase analysis of [alpha]- and [beta]-silicon nitrides. I. Estimation of errors

H. Toraya

Synopsis: Errors in the quantitative phase analysis (QPA) of [alpha]- and [beta]-silicon nitrides (Si3N4) using the mean normalized intensity method and the Rietveld method were estimated in theory and experiments.

Online August 1999


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J. Appl. Cryst. (1999). 32, 716-729  [ doi:10.1107/S0021889899004227 ]

Quantitative phase analysis of [alpha]- and [beta]-silicon nitrides. II. Round robins

H. Toraya, S. Hayashi and T. Nakayasu

Synopsis: Two round robins of the quantitative phase analysis of silicon nitrides using the mean normalized intensity method and the Rietveld method were conducted as one of the projects for establishing standard methods of characterizing advanced ceramic materials.

Online August 1999


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J. Appl. Cryst. (1999). 32, 730-735  [ doi:10.1107/S0021889899004288 ]

A Gaussian-Hermite polynomials function for X-ray diffraction profile fitting

F. Sánchez-Bajo and F. L. Cumbrera

Synopsis: This work proposes a new peak-shape function for modelling X-ray powder diffraction profiles, based on the use of the Gaussian function and a Hermite polynomials series expansion.

Online August 1999


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J. Appl. Cryst. (1999). 32, 736-743  [ doi:10.1107/S0021889899004380 ]

On the problem of overlapping [omega] scans measured on thin films deposited on monocrystal substrates

D. Machajdík, A. Pevala, A. Rosová, K. Fröhlich, J. Souc, F. Weiss and A. Figueras

Synopsis: An experimental study on the nature of extremely narrow overlapped maxima on X-ray diffraction [omega] scans is presented.

Online August 1999


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J. Appl. Cryst. (1999). 32, 744-754  [ doi:10.1107/S002188989900480X ]

Second-order neutron optics of three-axis spectrometers. I. Quasielastic scattering

A. D. Stoica, M. Popovici and W. B. Yelon

Synopsis: Second-order aberrations in bent-crystal three-axis spectrometers have been derived and verified experimentally. Substantial improvement of resolution was achieved through control of second-order effects.

Online August 1999


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J. Appl. Cryst. (1999). 32, 755-760  [ doi:10.1107/S0021889899005221 ]

High-resolution transmission electron microscopy study of the [varphi]'- and [delta]-AlON spinel phases of the pseudo-binary section AlN-Al2O3

P. Tabary, C. Servant and M. Guymont

Synopsis: High-resolution electron-microscopy observations support the previous structural model proposed for the [varphi]'- and [delta]-AlON spinel phases which allows for the double modulation of composition and displacement of the anions and cations.

Online August 1999


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J. Appl. Cryst. (1999). 32, 761-769  [ doi:10.1107/S0021889899005233 ]

Structure of sodium para-hydroxybenzoate, NaO2C-C6H4OH by powder diffraction: application of a phenomenological model of anisotropic peak width

R. E. Dinnebier, R. Von Dreele, P. W. Stephens, S. Jelonek and J. Sieler

Synopsis: The structure of sodium para-hydroxybenzoate has been solved ab initio by high-resolution X-ray powder diffraction; the quality of the powder data permits the detection of the position of the H atom connected to the phenolate. The sample shows extreme anisotropic peak broadening which could be satisfactorily modelled by a recently developed function.

Online August 1999


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J. Appl. Cryst. (1999). 32, 770-778  [ doi:10.1107/S0021889899005506 ]

A self-consistent method for X-ray diffraction analysis of multiaxial residual-stress fields in the near-surface region of polycrystalline materials. I. Theoretical concept

C. Genzel

Synopsis: The theoretical background of a new formalism in X-ray stress analysis (XSA) is derived. It allows the self-consistent evaluation of steep multiaxial residual-stress gradients in the near-surface region of polycrystalline materials from the strain data, which are measured in the scattering-vector mode of the XSA.

Online August 1999


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J. Appl. Cryst. (1999). 32, 779-787  [ doi:10.1107/S0021889899005518 ]

A self-consistent method for X-ray diffraction analysis of multiaxial residual-stress fields in the near-surface region of polycrystalline materials. II. Examples

C. Genzel, M. Broda, D. Dantz and W. Reimers

Synopsis: A newly developed formalism for the analysis of steep residual-stress gradients in the near-surface region of polycrystalline materials is applied to several practical cases. It yields the in-plane stresses, [sigma]11([tau]) and [sigma]22([tau]), the strain-free lattice spacing, d0(hkl), and, for well pronounced lattice-spacing depth profiles, even the out-of-plane stress, [sigma]33([tau]), in a self-consistent way.

Online August 1999


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J. Appl. Cryst. (1999). 32, 788-798  [ doi:10.1107/S002188989900549X ]

Automatic orientation determination from Kikuchi patterns

A. Morawiec

Synopsis: Formal aspects of automatic crystal orientation determination from Kikuchi patterns are discussed. Reliability of automatically obtained results and their sensitivity to experimental errors are investigated.

Online August 1999


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J. Appl. Cryst. (1999). 32, 799-807  [ doi:10.1107/S0021889899005737 ]

Laboratory X-ray powder diffraction: a comparison of different geometries with special attention to the usage of the Cu K[alpha] doublet

M. Oetzel and G. Heger

Synopsis: It is shown how measurements using the K[alpha] doublet influence evaluation procedures such as stripping, single-line analysis and Rietveld refinement. Moreover, a detailed description of the line-shape behaviour for different geometrical arrangements of powder diffractometers is given.

Online August 1999


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J. Appl. Cryst. (1999). 32, 808-813  [ doi:10.1107/S0021889899005853 ]

X-ray powder diffraction quantitative analysis performed in situ at high temperature: application to the determination of NiO in ceramic pigments

A. F. Gualtieri, E. Mazzucato, P. Venturelli, A. Viani, P. Zannini and L. Petras

Synopsis: This is the first report of the application of in situ high-temperature quantitative phase analysis. The application to NiO in ceramic pigments is described.

Online August 1999


cryocrystallography papers


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J. Appl. Cryst. (1999). 32, 814-820  [ doi:10.1107/S0021889899005026 ]

Use of an open-flow helium cryostat for macromolecular cryocrystallography

B. L. Hanson, A. Martin, J. M. Harp, D. A. Parrish, C. G. Bunick, K. Kirschbaum, A. A. Pinkerton and G. J. Bunick

Synopsis: A helium cryostat developed at the University of Toledo has been used to flash-cool and collect data from crystals of lysozyme and myoglobin, including flash-cooled crystals large enough for neutron diffraction purposes. The liquid-He consumption of the device is sufficiently low to allow the acquisition of complete diffraction data from a crystal on a single tank of He, and should expand He-temperature data-collection opportunities.

Online August 1999


teaching and education


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J. Appl. Cryst. (1999). 32, 821-823  [ doi:10.1107/S002188989900446X ]

Pepinsky's Machine: an interactive graphics-based Fourier synthesis program with applications in teaching and research

N. M. Glykos

Synopsis: A computer program has been developed which can be used both as a teaching aid to illustrate the principles and the application of the Fourier series in crystallography, and as a research tool to permit the systematic calculation of permutation syntheses for all centrosymmetric plane groups.

Online August 1999


short communications


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J. Appl. Cryst. (1999). 32, 824-826  [ doi:10.1107/S0021889899004471 ]

An improved goniometer head for high-temperature single-crystal X-ray diffraction

P. Delarue and M. Jannin

Synopsis: A reliable and inexpensive goniometer head has been designed and a high-temperature version has been tested at 973 K on a K0.88Rb0.12TiOPO4 crystal.

Online August 1999


computer programs


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J. Appl. Cryst. (1999). 32, 827-832  [ doi:10.1107/S0021889899004859 ]

DATPROC9: a data-processing program based on a new extension of the learnt-profile method

E. Galdecka

Synopsis: Computer modelling based on the extended learnt profile is used to refine the calculated net intensities. The user may select the learnt-profile model, from three available, in order to obtain a name.hkl file for crystal structure determination or to view the intensity plots of the measured profiles and their models.

Online August 1999


laboratory notes


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J. Appl. Cryst. (1999). 32, 833-836  [ doi:10.1107/S0021889899006032 ]

A high-temperature furnace for X-ray diffraction with directly machined [alpha]-Al2O3 ceramic parts

M. Estermann, H. Reifler, W. Steurer, F. Filser, P. Kocher and L. J. Gauckler

Synopsis: A high-temperature furnace, operating between ambient temperature and 1500 K, is described for the automatic collection of X-ray diffraction data on the Mar345 imaging-plate detector system. The complex ceramic parts were produced from presintered [alpha]-Al2O3 precompacts.

Online August 1999


computer program abstracts


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J. Appl. Cryst. (1999). 32, 837-838  [ doi:10.1107/S0021889899006020 ]

WinGX suite for small-molecule single-crystal crystallography

L. J. Farrugia

Synopsis: WinGX is a suite of Microsoft Windows™ programs for the processing, solution, refinement and publication of single-crystal diffraction data.

Online August 1999


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J. Appl. Cryst. (1999). 32, 838  [ doi:10.1107/S0021889899003039 ]

PowderX: Windows-95-based program for powder X-ray diffraction data processing

C. Dong

Synopsis: A Windows-95-based program for powder X-ray diffraction data processing, PowderX, is presented.

Online August 1999


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J. Appl. Cryst. (1999). 32, 838-839  [ doi:10.1107/S0021889899004860 ]

DISCUS, a program for diffuse scattering and defect structure simulations - update

Th. Proffen and R. B. Neder

Synopsis: An update of the program DISCUS for diffuse scattering and defect structure simulations is presented.

Online August 1999


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J. Appl. Cryst. (1999). 32, 839-840  [ doi:10.1107/S0021889899007451 ]

XFPA98: a program for automatic structure determination and automatic refinement

F. Pavelcik

Synopsis: XFPA98 is a versatile tool for direct Patterson solution and preliminary refinement of crystal structures.

Online August 1999


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

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