Journal of Applied Crystallography

    

J. Appl. Cryst. (2000). 33, 997-1005  [ doi:10.1107/S0021889800004556 ]

Anisotropic diffraction peak broadening and dislocation substructure in hydrogen-cycled LaNi₅ and substitutional derivatives

R. Cerný, J.-M. Joubert, M. Latroche, A. Percheron-Guégan and K. Yvon

Synopsis: Hydrogen absorption-desorption cycling in LaNi₅ and substitutional derivatives induces anisotropic diffraction peak broadening. The change of the anisotropy as a function of substitution (by Co, Mn, Al, Fe, Cu, Sn and Ce) is discussed in terms of various dislocation substructures.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1006-1018  [ doi:10.1107/S0021889800004696 ]

Corrections for surface X-ray diffraction measurements using the Z-axis geometry: finite size effects in direct and reciprocal space

O. Robach, Y. Garreau, K. Aïd and M. B. Véron-Jolliot

Synopsis: Two approaches to the correction of grazing-incidence X-ray diffraction data are described: one taking into account the evolution of the diffracting area during an scan; the other considering the case of finite-width rods, under the point-like sample approximation. A full numerical simulation is also presented.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1019-1022  [ doi:10.1107/S0021889800006828 ]

X-ray diffraction from perfect silicon crystals distorted by surface acoustic waves

R. Tucoulou, R. Pascal, M. Brunel, O. Mathon, D. V. Roshchupkin, I. A. Schelokov, E. Cattan and D. Remiens

Synopsis: High-resolution X-ray diffraction measurements were carried out on ZnO/Si devices under surface acoustic wave excitation and revealed some very clear satellite diffraction peaks that are obtained from the sinusoidal modulation of the near-surface region. This experiment shows that the propagation of a Rayleigh surface acoustic wave in a perfect crystal acts as a dynamical diffraction grating.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1023-1030  [ doi:10.1107/S0021889800005975 ]

X-ray topographic determination of the granular structure in a graphite mosaic crystal: a three-dimensional reconstruction

M. Ohler, M. Sanchez del Rio, A. Tuffanelli, M. Gambaccini, A. Taibi, A. Fantini and G. Pareschi

Synopsis: Section topographs recorded at different spatial locations and at different rocking angles of a highly oriented pyrolytic graphite crystal allow three-dimensional maps of the local angular-dependent scattering power to be obtained. The maps allow the extraction of information on local structural parameters such as size, form and internal mosaic spread of crystalline domains, and represent a new approach to the characterization of mosaic crystals.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1031-1036  [ doi:10.1107/S0021889800005112 ]

Novel image analysis of two-dimensional X-ray fiber diffraction patterns: example of a polypropylene fiber drawing study

S. Ran, X. Zong, D. Fang, B. S. Hsiao, B. Chu and R. Ross

Synopsis: On-line X-ray studies of structural development during continuous polypropylene fiber drawing were carried out using synchrotron radiation. A unique image analysis method was introduced to extract quantitative information on the crystal, amorphous and mesomorphic fractions.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1037-1045  [ doi:10.1107/S0021889800005124 ]

Study of disorder in a tetragonal tungsten bronze ferroelectric relaxor: a structural approach

V. Hornebecq, C. Elissalde, F. Weill, A. Villesuzanne, M. Menetrier and J. Ravez

Synopsis: Electron diffraction analysis, nuclear magnetic resonance measurements, structural determination and refinements were performed on two ferroelectric lead-containing ceramics (classical and relaxor), with tetragonal tungsten bronze structure, in order to investigate the origin of the relaxor behaviour in such compounds.

Online 1 August 2000

    

J. Appl. Cryst. (2000). 33, 1046-1050  [ doi:10.1107/S0021889800005318 ]

High-energy X-ray diffuse scattering using Weissenberg flat-cone geometry

B. D. Butler, D. R. Haeffner, P. L. Lee and T. R. Welberry

Synopsis: A description of a diffuse X-ray scattering measurement technique using high-energy X-rays in Weissenberg flat-cone geometry is presented.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1051-1058  [ doi:10.1107/S0021889800004222 ]

Double-crystal diffraction imaging with a small effective divergence source: application to the magneto-acoustic vibrations in FeBO₃

I. Matsouli, V. V. Kvardakov and J. Baruchel

Synopsis: Ultrasonic standing waves, excited in FeBO₃ (111) crystal plates through magneto-elastic coupling, have been visualized using monochromatic Bragg diffraction imaging (topography) employing synchrotron radiation. The images depend strongly on whether diffraction by the sample occurs in the same plane as in the double-crystal monochromator, or in the perpendicular plane.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1059-1066  [ doi:10.1107/S0021889800004258 ]

New methods for diffraction stress measurement: a critical evaluation of new and existing methods

J.-D. Kamminga, T. H. de Keijser, E. J. Mittemeijer and R. Delhez

Synopsis: New methods of diffraction stress analysis of polycrystalline materials, consisting of cubic elastically anisotropic crystallites, are proposed and compared with existing methods. The new methods do not require diffraction elastic constants.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1067-1074  [ doi:10.1107/S0021889800004611 ]

The crystal neutron diffractometer resolution function, spatial effects included

I. Ionita and A. D. Stoica

Synopsis: A procedure for computing the resolution function for a crystal neutron diffractometer, taking into account the spatial configuration of the experimental setup and the monochromator curvature, is presented.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1075-1081  [ doi:10.1107/S0021889800004878 ]

Etude structurale d'un hydrate 10 Å instable de kaolinite

S. Jemai, A. Ben Haj Amara, J. Ben Brahim and A. Plançon

Synopsis: The treatment of KGa-1 kaolinite with dimethyl sulfoxide and ammonium fluoride heated at 383 K provides an unstable hydrated phase characterized by a 10 Å basal distance; when air-dried, this hydrate gives a dehydrated phase at 7.15 Å. This hydrate has been structurally characterized via a comparison between experimental and calculated X-ray diffraction profiles.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1082-1087  [ doi:10.1107/S0021889800005343 ]

Using a prism to reject or select harmonic reflections in an X-ray monochromator

Z. Zhong

Synopsis: X-ray refraction by a prism has been used to discriminate between different harmonic orders of a two-crystal monochromator. Rejection of higher-order harmonics and selection of specific harmonic order is demonstrated.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1088-1101  [ doi:10.1107/S0021889800005951 ]

Global least-squares determination of Eulerian angles from single electron diffraction patterns of tilted crystals

E. Dimmeler and R. R. Schröder

Synopsis: A least-squares procedure is used to determine the orientation of a crystal in a tilted diffraction geometry from a single electron diffraction pattern. The scheme can be universally applied to crystals with one, only a few, or many crystallographic layers and yields highly accurate Eulerian angles of the diffraction geometry.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1102-1112  [ doi:10.1107/S0021889800005963 ]

Determination of lattice-transform density profiles for multilayered three-dimensional microcrystals in electron crystallography

E. Dimmeler, O. Vossen and R. R. Schröder

Synopsis: Applying least-squares and correlation methods it is possible to separate the shape of the reciprocal lattice from the molecular transform using a single electron diffraction pattern. This separation is one crucial step in the structure determination of beam-sensitive multilayered three-dimensional microcrystals.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1113-1118  [ doi:10.1107/S0021889800006300 ]

Contrast analysis of the composition of ribosomes extracted with different purification procedures

G. Briganti, R. Giordano, P. Londei and F. Valle

Synopsis: The composition and hydration of E. coli ribosomes isolated with different purification protocols has been analysed by combining two experimental techniques: measurements of small-angle neutron scattering, for two different isotopic solvent compositions, and refractive index increments.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1119-1121  [ doi:10.1107/S0021889800006567 ]

Measurement of the fine structure factors and extinction distance by convergent-beam electron diffraction in Co₃Ti with and without B doping

M.-Y. Wu, J. Zhu, S.-Y. Li, Z.-H. Du and S.-L. Li

Synopsis: Using convergent-beam electron diffraction (CBED), the fine structure factors of Co₃Ti alloys have been measured and the effects of boron microalloying on the fine structure factors have been studied. The extinction distances of Co₃Ti have been obtained by both Kelly's method and the CBED simulation method.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1122-1127  [ doi:10.1107/S0021889800006750 ]

Calculation of diffraction line profiles from specimens with dislocations. A comparison of analytical models with computer simulations

J.-D. Kamminga and R. Delhez

Synopsis: A method is proposed to calculate diffraction line profiles from specimens with dislocations. Calculated results are compared to results obtained from analytical models.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1128-1135  [ doi:10.1107/S0021889800006932 ]

Data smoothing and distortion of X-ray diffraction peaks. I. Theory

H. Wang and J. Zhou

Synopsis: Smoothing distortions of an X-ray diffraction peak are theoretically analysed and formulae to calculate the smoothing-induced changes of all parameters of a peak are derived.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1136-1142  [ doi:10.1107/S0021889800006944 ]

Data smoothing and distortion of X-ray diffraction peaks. II. Application

H. Wang and J. Zhou

Synopsis: Based on the analysis of geometric relations, it is found that the amplitude of the distortion of the full width at half-maximum (FWHM) of a peak after smoothing is the largest among the distortions of the seven parameters of a peak: maximum intensity, FWHM, shape, asymmetry, integral intensity, peak position and integral width. It is found that the smoothing-induced distortions of an actual X-ray diffraction peak trend towards those of ideal curves.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1143-1148  [ doi:10.1107/S0021889800007184 ]

Reporting and evaluating absolute-structure and absolute-configuration determinations

H. D. Flack and G. Bernardinelli

Synopsis: Detailed practical and numerical information is provided for undertaking and evaluating absolute-structure and absolute-configuration determinations.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1149-1153  [ doi:10.1107/S0021889800007743 ]

Periodically poled KTA crystal investigated using coherent X-ray beams

P. Pernot-Rejmánková, P. A. Thomas, P. Cloetens, F. Lorut, J. Baruchel, Z. W. Hu, P. Urenski and G. Rosenman

Synopsis: The distribution of inverted ferroelectric domains on the surface and within the bulk of a periodically poled KTA single crystal has been observed using a simple synchrotron X-ray diffraction imaging setup. This technique allows one to reveal the phase difference between the waves that are Bragg diffracted from adjacent domains via free-space propagation (Fresnel diffraction).

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1154-1161  [ doi:10.1107/S002188980000697X ]

Computing in macromolecular crystallography using a parallel architecture

K. Diederichs

Synopsis: Calculations in macromolecular crystallography inherently have a high degree of parallelism. The OpenMP programming interface can be used in crystallographic programs to reduce computation times on multiprocessor computers.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1162-1174  [ doi:10.1107/S0021889800007251 ]

Experimental determination of the instrumental transparency function of texture goniometers

K. Moras, A. H. Fischer, H. Klein and H. J. Bunge

Synopsis: The instrumental transparency functions of five commercially available texture goniometers were measured with highly perfect, monocrystalline silicon samples. The transparency function is the fundamental characteristic of a texture goniometer, defining its angular resolving power.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1175-1176  [ doi:10.1107/S0021889800007275 ]

High-pressure studies of the cubic to rhombohedral transformation in NbO₂F

S. Carlson

Synopsis: A detailed study of the cubic to rhombohedral high-pressure transition of NbO₂F has been performed by powder diffraction using synchrotron X-ray radiation and diamond anvil cells, showing that the transition starts at 0.28 and is complete at 0.65 GPa.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1177-1179  [ doi:10.1107/S0021889800006622 ]

LAPODS: a computer program for refinement of lattice parameters using optimal regression

C. Dong and J. I. Langford

Synopsis: LAPODS is an upgraded version of the program LAPOD for the refinement of lattice parameters. It has several new features, including automatic determination of significant systematic errors, based on statistical considerations.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1180-1186  [ doi:10.1107/S0021889800006427 ]

New techniques for indexing: N-TREOR in EXPO

A. Altomare, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, R. Rizzi and P.-E. Werner

Synopsis: New techniques are described for indexing a powder pattern. The program, an evolution of TREOR90, has been integrated into the package EXPO.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1187-1188  [ doi:10.1107/S0021889800005732 ]

BEAM-ish: a graphical user interface for the physical characterization of macromolecular crystals

J. Lovelace, E. H. Snell, M. Pokross, A. S. Arvai, C. Nielsen, N.-H. Xuong, H. D. Bellamy and G. E. O. Borgstahl

Synopsis: BEAM-ish is a graphical user interface that manages the processing of multiple super-fine -sliced diffraction images and seamlessly integrates several programs for mosaicity calculations.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1189  [ doi:10.1107/S0021889800005410 ]

Development of a graphical interface for the Rietveld refinement program DBWS

L. Bleicher, J. M. Sasaki and C. O. Paiva Santos

Synopsis: The program DBWS Tools is an application for DBWS users that compiles input control files for versions 9411 and 9807 and manages program execution using a Windows 95/98/NT interface.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1190-1191  [ doi:10.1107/S0021889800007135 ]

SUBGROUPGRAPH: a computer program for analysis of group-subgroup relations between space groups

S. Ivantchev, E. Kroumova, G. Madariaga, J. M. Pérez-Mato and M. I. Aroyo

Synopsis: The main aim of SUBGROUPGRAPH is a detailed study of a group-subgroup relation between two space groups, G > H, including the construction of chains of maximal subgroups for G > H for a specified/non-specified index i = |G:H| (the so-called G-H graph), the determination of the number of the different H_k < G, H_k H, and their distribution into classes of conjugate subgroups relative to G, etc.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1192  [ doi:10.1107/S0021889800007123 ]

PDFgetN: a user-friendly program to extract the total scattering structure factor and the pair distribution function from neutron powder diffraction data

P. F. Peterson, M. Gutmann, Th. Proffen and S. J. L. Billinge

Synopsis: This program allows S(Q) and the pair-distribution function to be determined from a variety of time-of-flight neutron powder diffractometers. Features are a graphical user interface and permanent storage of processing parameters.

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1193  [ doi:10.1107/S0021889800007202 ]

TOPOS3.2: a new version of the program package for multipurpose crystal-chemical analysis

V. A. Blatov, A. P. Shevchenko and V. N. Serezhkin

Synopsis: The program package TOPOS is intended for the automation of all stages of crystal-chemical analysis.

Online 1 August 2000

    

J. Appl. Cryst. (2000). 33, 1194  [ doi:10.1107/S0021889800008323 ]

Comment on CRUNCH: a phase refinement program for high-resolution macromolecular structures by Langs, Blessing & Smith (2000)

R. A. G. de Graaff and R. de Gelder

Synopsis: Comment on Langs, Blessing & Smith [J. Appl. Cryst. (2000), 33, 174-175].

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1194  [ doi:10.1107/S0021889800008335 ]

Response to de Graaff & de Gelder's comment on CRUNCH: a phase refinement program for high-resolution macromolecular structures

D. A. Langs, R. H. Blessing and G. D. Smith

Synopsis: Response to comment on Langs, Blessing & Smith [J. Appl. Cryst. (2000), 33, 174-175].

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1195  [ doi:10.1107/S0021889899016660 ]

Jerry B. Cohen

Online 1 August 2000

 

J. Appl. Cryst. (2000). 33, 1195  [ doi:10.1107/S0021889800008281 ]

European Crystallography Prize

Online 1 August 2000