Journal of Applied Crystallography

Volume 31, Part 6 (December 1998)



[Issue Author Index][Volume Author Index]
[Cover illustration] Cover illustration: Powder diffraction pattern of LaB6 obtained using a 200 × 400  mm flat imaging plate mounted at an angle of 45° with the incoming X-ray beam. Experimental conditions: [lambda] = 0.8884 Å, D0 = 104 mm, exposure time 60 s. Courtesy of Poul Norby.

obituaries


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J. Appl. Cryst. (1998). 31, 829-830  [ doi:10.1107/S0021889898009182 ]

Pieter Maarten de Wolff 1919-1998

T. Janssen and F. Tuinstra

Online 1 December 1998


research papers


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J. Appl. Cryst. (1998). 31, 831-834  [ doi:10.1107/S0021889897019602 ]

Strain Determination in Epitaxic Films of Materials of Orthorhombic Symmetry by High-Resolution X-ray Diffraction

L. De Caro and L. Tapfer

Synopsis: A new expression of the X-ray incidence parameter is derived in order to evaluate the lattice strain by high-resolution X-ray diffraction rocking curves of heterostructures made of materials with different crystallographic symmetry. In particular, high-Tc perovskite superconductors deposited on substrates of cubic symmetry are considered.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 835-840  [ doi:10.1107/S0021889898005846 ]

Neutron Transmission of Single-Crystal Sapphire

D. F. R. Mildner and G. P. Lamaze

Synopsis: The thermal and cold neutron transmission characteristics of high-grade single-crystal sapphire show negligible degradation after irradiation. The results are analyzed in terms of single-photon scattering. Poorer grade sapphire has similar properties.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 841-844  [ doi:10.1107/S0021889898005858 ]

Neutron Transmission of a Single-Crystal MgO Filter

P. Thiyagarajan, R. K. Crawford and D. F. R. Mildner

Synopsis: By reducing most of the single-photon scattering, a liquid-nitrogen-cooled single-crystal magnesium oxide filter has thermal and cold neutron transmission characteristics superior to those of room-temperature single-crystal sapphire.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 845-850  [ doi:10.1107/S0021889898006773 ]

Structure Analysis of Intercalated Zirconium Phosphate Using Molecular Simulation

P. Capková, L. Benes, K. Melánová and H. Schenk

Synopsis: A combination of X-ray diffraction and molecular-mechanics simulations in the Cerius2 modelling environment has been used in the structure analysis of [alpha]-zirconium phosphate intercalated with ethanol.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 851-861  [ doi:10.1107/S0021889898006876 ]

Axial Divergence in a Conventional X-ray Powder Diffractometer. I. Theoretical Foundations

R. W. Cheary and A. A. Coelho

Synopsis: The theory is developed for generating the aberration profiles for axial divergence in a conventional diffractometer in terms of the dimensions of the X-ray source, the sample, the receiving slit and the Soller slits in the incident and/or diffracted beams.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 862-868  [ doi:10.1107/S0021889898006888 ]

Axial Divergence in a Conventional X-ray Powder Diffractometer. II. Realization and Evaluation in a Fundamental-Parameter Profile Fitting Procedure

R. W. Cheary and A. A. Coelho

Synopsis: Profiles for a conventional powder diffractometer are generated and fitted using a fundamental-parameters approach which incorporates an accurate axial divergence function. The fit and the self-consistency of the approach are evaluated for different instrument configurations and a range of reference samples.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 869-873  [ doi:10.1107/S0021889898007031 ]

Organization Modes and Electron Radiation Damage of Cardiolipin Crystals

G. Valdrè and U. Muscatello

Synopsis: Microcrystals of cardiolipin (tetraacyldiphosphatidylglycerol) prepared according to different procedures have been studied by transmission electron microscopy and selected-area electron diffraction. The radiation damage has been assessed.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 874-880  [ doi:10.1107/S0021889898007560 ]

Structure Investigations of Molecular Crystals Containing the Ring System Cyclo-tris(2,6-pyridylformamidine) by Means of X-ray Powder Diffraction and Force-Field-Constrained Rietveld Refinement

P. Friedel, J. Tobisch, D. Jehnichen, J. Bergmann, T. Taut, M. Rillich, C. Kunert and F. Böhme

Synopsis: The refinement of powder diffraction data of partly crystalline organic compounds is described. Calculation of the structural data was performed using a Rietveld algorithm, taking the results of other methods into consideration.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 881-889  [ doi:10.1107/S0021889898007699 ]

Simultaneous Rheology and Small-Angle Scattering Experiments on Block Copolymer Gels and Melts in Cubic Phases

I. W. Hamley, J. A. Pople, A. J. Gleeson, B. U. Komanschek and E. Towns-Andrews

Synopsis: Small-angle X-ray scattering is combined with simultaneous rheology to yield a wealth of information on the effect of shear on block copolymer melts and gels. The focus is on cubic micellar phases formed by amphiphilic block copolymers.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 890-898  [ doi:10.1107/S0021889898007778 ]

Characterization of Local Chemistry and Disorder in Synthetic and Natural [alpha]-Al2O3 Materials by X-ray Absorption Near-Edge Structure Spectroscopy

A. Mottana, T. Murata, A. Marcelli, G. Della Ventura, G. Cibin, Z. Y. Wu and R. Tessadri

Synopsis: X-ray absorption near-edge structure (XANES) spectra taken at the Al K edge on a pure synthetic [alpha]-Al2O3 sample, a natural corundum (ruby/sapphire), and five artificial alumina made for abrasives have been interpreted quantitatively on the basis of difference spectra. Three of the artificial alumina contain [beta]-Al2O3 as an admixed phase, the tetrahedral Al of which interferes with the predominant octahedral Al, while ruby/sapphire and the remaining two artificial alumina are very pure [alpha]-phases with minor substitutions of foreign atoms for their octahedral Al.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 899-909  [ doi:10.1107/S0021889898007833 ]

Simulation and Measurement of X-ray Diffraction from Single Crystals and Evaluation of Optimized Data Collection

A. Sarvestani, A. H. Walenta, E. Busetto, A. Lausi and R. Fourme

Synopsis: A simulation program for macromolecular diffraction patterns is presented which considers all essential parameters of the source, the sample and the detector. Tests and possible applications of the program are described.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 910-916  [ doi:10.1107/S0021889898008085 ]

A New Structural Model for Nongraphitic Carbons

H. Azuma

Synopsis: Why do the current crystallite models show a larger intensity in the small-angle region than the experimental values? This paper attempts to answer this question by providing a new model of the stacking structure of disordered carbon layers.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 917-921  [ doi:10.1107/S0021889898009194 ]

On the Estimation of the Termination Effect in Fourier Synthesis in X-ray Structure Analysis

Y. Takahashi, K. Ohshima, K. Yamamoto, K. Yukino and F. P. Okamura

Synopsis: An accurate structure analysis of a spherical LaB6 single crystal has been performed with the use of short-wavelength X-rays (WK[alpha]1) in order to estimate the termination effect in Fourier synthesis on the electron-density distribution (EDD). It is concluded that the effect on the EDD is negligible if data are taken up to \sin \theta/\lambda=2.0\;Å-1, because the negative values disappear completely from the map.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 922-928  [ doi:10.1107/S0021889898008735 ]

A New Algorithm for Space-Group Determination

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

Synopsis: Two algorithms are presented that determine the translational symmetry (TRS) and space group (RGS) of a crystal structure, both for synthesized compounds and computer-generated structures.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 929-935  [ doi:10.1107/S002188989800898X ]

Calculation of Single-Crystal Elastic Constants for Cubic Crystal Symmetry from Powder Diffraction Data

T. Gnäupel-Herold, P. C. Brand and H. J. Prask

Synopsis: A method that allows the calculation of single-crystal elastic constants from the diffraction elastic constants is presented. Values for the diffraction elastic constants have been obtained from diffraction measurements on polycrystals.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 936-944  [ doi:10.1107/S0021889898008991 ]

A Microfocus X-ray Tube Used with Focusing Collimators

U. W. Arndt, J. V. P. Long and P. Duncumb

Synopsis: An X-ray tube with a focal spot diameter between 10 and 20  µm is described which can be operated at about 20  W and which is used with ellipsoidal focusing mirrors to deliver an intensity at the sample that is comparable with the intensity achieved with rotating-anode generators and non-focusing collimators.

Online 1 December 1998


cryocrystallography papers


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J. Appl. Cryst. (1998). 31, 945-953  [ doi:10.1107/S0021889898005305 ]

Macromolecular Cryocrystallography: Cooling, Mounting, Storage and Transportation of Crystals

S. Parkin and H. Hope

Synopsis: A technique for direct cooling of crystals in liquid nitrogen has been developed. A set of implements has been designed and tested.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 954-956  [ doi:10.1107/S0021889898005299 ]

Cryocrystallography: effect of cooling medium on sample cooling rate

L. J. Walker, P. O. Moreno and H. Hope

Synopsis: Cooling rates in liquid nitrogen, liquid propane and nitrogen gas have been compared. Liquid nitrogen affords the most rapid cooling, nitrogen gas the slowest.

Online 1 December 1998


short communications


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J. Appl. Cryst. (1998). 31, 957-959  [ doi:10.1107/S0021889898004440 ]

Silver behenate powder as a possible low-angle calibration standard for small-angle neutron scattering

R. Gilles, U. Keiderling and A. Wiedenmann

Synopsis: Silver behenate powder (AgBE), one of the very few materials featuring Bragg reflections in the angular range accessible to small-angle neutron scattering (SANS) instruments, is suggested as a possible new wavelength calibration standard.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 960-962  [ doi:10.1107/S0021889898006785 ]

Patterson-oriented automatic structure determination. Organic structures

F. Pavelcik

Synopsis: Two new and two renewed procedures for structure determination based on symmetry minimum and/or superposition functions were applied to equal-atom structures. Fourier recycling is able to extract structure from noisy superposition maps.

Online 1 December 1998


computer programs


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J. Appl. Cryst. (1998). 31, 963-964  [ doi:10.1107/S0021889898008395 ]

RES2INS: a graphical interface for the SHELX program suite

L. J. Barbour and J. L. Atwood

Synopsis: A graphical computer program for the preparation of SHELXL instruction files is described.

Online 1 December 1998


CIF applications


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J. Appl. Cryst. (1998). 31, 965-968  [ doi:10.1107/S0021889898008978 ]

CIF Applications. X. Automatic Construction of CIF Input Functions: CifSieve

J. R. Hester and F. P. Okamura

Synopsis: A software package has been developed to read user-specified data from a CIF with a single C or Fortran function call. This approach involves simple additions to a CIF dictionary and significantly reduces the effort involved in creating a CIF interface. The procedure is applicable to both DDL1 and DDL2 dictionaries.

Online 1 December 1998


laboratory notes


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J. Appl. Cryst. (1998). 31, 969  [ doi:10.1107/S0021889898007705 ]

A versatile loading device for Guinier-Hägg sample holders and capillary tubes

N. Blaton, R. Vochten and R. Huysmans

Synopsis: A simple device for preparation of Guinier-Hägg-camera samples and easy filling of capillary tubes is described.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 970-971  [ doi:10.1107/S0021889898008401 ]

An inexpensive X-ray imaging device for use in camera/diffractometer alignment

I. G. Wood and P. A. Woods

Synopsis: A simple and inexpensive system for producing video images of collimated X-ray beams is described and is suitable for use as an alignment tool.

Online 1 December 1998


computer program abstracts


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J. Appl. Cryst. (1998). 31, 972  [ doi:10.1107/S0021889898002696 ]

NOPTSUS - a program for computing nonlinear-optical susceptibilities from structure data

Ch. Schetelich

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 972-973  [ doi:10.1107/S0021889897010388 ]

PINCER: a portable data-acquisition program based on a command language interpreter

M. C Miller, G. Oszlanyi, K. S. Ackroyd, C. Marshall, S. P. Collins, D. Laundy and R. J. Cernik

Synopsis: A command interpreter for instrument control with macro file input is described. It is flexible, extensible and portable and a wide variety of experimental areas are supported.

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 973  [ doi:10.1107/S0021889898010152 ]

VRML general position/symmetry diagrams of the 80 layer groups

D. Tshudy and D. B Litvin

Synopsis: General position/symmetry diagrams of the 80 layer groups are available in VRML format for viewing on a World Wide Web browser with a VRML viewer plug-in.

Online 1 December 1998


crystallographers


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J. Appl. Cryst. (1998). 31, 973-974  [ doi:10.1107/S002188989800908X ]

Crystallographers

Online 1 December 1998


new commercial products


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J. Appl. Cryst. (1998). 31, 974  [ doi:10.1107/S0021889898015301 ]

New Books on Ceramics

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 974  [ doi:10.1107/S0021889898015295 ]

Cryo Cooler for X-ray Crystallography

Online 1 December 1998


international union of crystallography


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J. Appl. Cryst. (1998). 31, 974-976  [ doi:10.1107/S0021889898013740 ]

Prices of IUCr journals

Online 1 December 1998


books received


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J. Appl. Cryst. (1998). 31, 976  [ doi:10.1107/S0021889898005330 ]

Defect recognition and image processing in semiconductors 1997

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 976  [ doi:10.1107/S002188989800630X ]

Ternary and multinary compounds

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 976  [ doi:10.1107/S0021889898015313 ]

Simulations for solid state physics. An interactive teaching resource for students and teachers

Online 1 December 1998


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J. Appl. Cryst. (1998). 31, 976  [ doi:10.1107/S0021889898015325 ]

X-ray charge densities and chemical bonding

Online 1 December 1998


J. Appl. Cryst.. (1998). 31, 0

forthcoming meetings and short courses.


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