Journal of Applied Crystallography

Contents of Volume 28, Part 5 (1 October 1995)

Cover illustration: The observed X-ray diffuse scattering in the (h0l) section of 1,3-dibromo-2,5-diethyl-4,6-dimethylbenzene. Courtesy of T. R. Welberry and B. D. Butler.

RESEARCH PAPERS

J. Appl. Cryst. (1995). 28, 461

Quantitative Analysis of Synchrotron Laue Diffraction Patterns in Macromolecular Crystallography

Z. Ren and K. Moffat

Synopsis

Accurate and complete structure-factor amplitudes can be obtained from synchrotron Laue diffraction patterns by a series of novel approaches to Laue pattern integration and data scaling.

J. Appl. Cryst. (1995). 28, 482

Deconvolution of Energy Overlaps in Laue Diffraction

Z. Ren and K. Moffat

Synopsis

Energy overlaps in Laue diffraction can be resolved to yield complete and accurate sets of structure-factor amplitudes even at very low resolution.

J. Appl. Cryst. (1995). 28, 494

Determination of the Cation Distribution in NiFe₂(PO₄)₂ using Resonant X-ray and Neutron Powder Diffraction

J. K. Warner, A. K. Cheetham and D. E. Cox

Synopsis

The distribution of divalent iron and nickel over two metal sites in the solid solution NiFe₂(PO₄)₂, sarcopside, has been investigated by resonant X-ray and time-of-flight neutron powder diffraction. The appropirate value of f^' for iron was measured by diffraction from a chemically similar compound, Fe₃(PO₄)₂.

J. Appl. Cryst. (1995). 28, 503

Time-of-Flight Texture Analysis of Limestone Standard: Dubna Results

K. Walther, J. Heinitz, K. Ullemeyer, M. Betzl and H.-R. Wenk

Synopsis

The texture of a deformed limestone sample has been investigated by neutron time-of-flight diffraction. The results obtained are compared with the results from other facilities for the same sample.

J. Appl. Cryst. (1995). 28, 508

Thermal Expansion and Crystal Chemistry of (Sr_1-x, K_2x)Zr₄(PO₄)₆ Ceramic

D.-M. Liu, L.-J. Lin and C.-J. Chen

Synopsis

The coefficient of thermal expansion and lattice structure of (Sr_1-x, K_2x)Zr₄(PO₄)₆ ceramic have been characterized using a dilatometer and a high-temperature X-ray diffractometer.

J. Appl. Cryst. (1995). 28, 513

The Performance of the Australian Powder Diffractometer at the Photon Factory, Japan

T. M. Sabine, B. J. Kennedy, R. F. Garrett, G. J. Foran and D. J. Cookson

Synopsis

A Debye-Scherrer powder camera, with image plates instead of film, has been installed on a synchrotron source. Its performance has been tested with data taken over a range of wavelengths from a rutile specimen.

J. Appl. Cryst. (1995). 28, 518

Direct Fitting of Grazing-Incidence Neutron and X-ray Reflectivity Profiles using the Kinematic Approximation

E. M. Lee and J. E. Milnes

Synopsis

A new method of directly fitting combinations of X-ray and neutron grazing-incidence reflection profiles based on the kinematic approximation is described, demonstrated and compared with existing methods.

J. Appl. Cryst. (1995). 28, 527

Improvements in the Quantitative Evaluation of Three-Dimensional Texture. I. The Nature of the Information Obtained from Pole Figures

L.-G. Yu, H. Guo, B. C. Hendrix, K.-W. Xu and J.-W. He

Synopsis

The evaluation of three-dimensional orientation distribution functions from two-dimensional pole figures is re-examined. A practical relationship between pole-figure accuracy and the number of useful pole figures is determined.

J. Appl. Cryst. (1995). 28, 532

Improvements in the Quantitative Evaluation of Three-Dimensional Texture. II. The Pole-Figure-Multiplying Method

L.-G. Yu, H. Guo, B. C. Hendrix, K.-W. Xu and J.-W. He

Synopsis

A new simple method is proposed for determination of the orientation distribution function of texture analysis.

J. Appl. Cryst. (1995). 28, 534

Simulation of Powder Diffraction Diagrams from Disordered and Imperfect Graphitic Layers

Yu. G. Andreev and T. Lundström

Synopsis

X-ray diffraction patterns from distorted graphitic particles and finite honeycomb carbon layers are calculated using the Debye equation and real-space models of atomic arrangements.

J. Appl. Cryst. (1995). 28, 540

Lattice Parameters of Boron Nitride Polymorphous Modifications as a Function of Their Crystal-Structure Perfection

A. V. Kurdyumov, V. L. Solozhenko and W. B. Zelyavski

Synopsis

The fundamental reference values of lattice parameters for all crystalline modifications of BN have been established.

J. Appl. Cryst. (1995). 28, 546

A Small-Angle X-ray Scattering Study of the Binding of Cyclosporin A to Cyclophilin

R. B. Knott, M. Capel, S. Hansen and R. E. Handschumacher

Synopsis

The small-angle X-ray scattering technique has been used to investigate structural characteristics in solution of (i) the protein cyclophilin and (ii) the cyclosporin-A/cyclophilin complex. Results indicate that cyclophilin has a compact spherical shape with a radius of gyration of 16.3 Å.

J. Appl. Cryst. (1995). 28, 553

Small-Angle X-ray Scattering Size Parameters and Higher Moments of the Particle-Size Distribution Function in the Asymptotic Stage of Ostwald Ripening

J. Möller, R. Kranold, J. Schmelzer and U. Lembke

Synopsis

A method is presented that allows the applicability of the Lifshitz-Slyozov-Wagner theory of Ostwald ripening to be proved for phase-separating systems. The method is based on experimental SAXS data that characterize the size-distribution type established.

J. Appl. Cryst. (1995). 28, 561

Simultaneous Position-Resolved Determination of Phase and Stress Distributions by means of an X-ray Diffractometer with a Two-Dimensional Position-Sensitive Detector

D. Stephan, G. Grosse and K. Wetzig

Synopsis

A diffractometer system with an area detector and a suitable Soller plate collimator allows efficient position-resolved and visualized phase and stress analysis simultaneously for a sample straight line in the centimetre scale. The principal application possibilities are demonstrated with examples.

J. Appl. Cryst. (1995). 28, 568

Mixing Symmetric and Oblique Bragg Reflections in Rigid Channel-Cut Crystals

M. Hart, T. Koga and Y. Takano

Synopsis

Oblique and symmetric Bragg reflections can in some cases (e.g. 220 from germanium) be mixed in a channel-cut monochromator without loss of intensity.

J. Appl. Cryst. (1995). 28, 571

Determination of the Orientation of a Parent beta Grain from the Orientations of the Inherited alpha Plates in the Phase Transformation from Body-Centred Cubic to Hexagonal Close Packed

M. Humbert, F. Wagner, H. Moustahfid and C. Esling

Synopsis

From the orientation of three differently oriented alpha plates inherited from the b.c.c.-h.c.p. phase transformation, it is possible to determine the orientation of the parent beta grain.

J. Appl. Cryst. (1995). 28, 577

Determination of the Space Group of Ceramic BaO.Pr₂O₃.4TiO₂ by Electron Diffraction

F. Azough, P. E. Champness and R. Freer

Synopsis

Ceramic specimens of BaO.Pr₂O₃.4TiO₂ were prepared by a classical mixed-oxide route. Transmission-electron-microscope electron diffraction studies showed that the dielectric has orthorhombic symmetry with the space group Pnam, one of the two possible space groups previously identified for Ba_3.75Ln_9.5Ti₁₈O₅₄.

J. Appl. Cryst. (1995). 28, 582

Estimation of the Minimum Grain Number for the Orientation Distribution Function Calculation from Individual Orientation Measurements on Fe-3%Si and Ti-4Al-6V Alloys

T. Baudin, J. Jura, R. Penelle and J. Pospiech

Synopsis

The calculation of characteristics describing the texture as well as relations between orientations and morphological features of the microstructure are based on single orientation measurements. For such experimental data, it is essential to estimate the number of necessary measurements of single orientations for a statistically significant representation of the investigated quantity, which in the present paper is the orientation distribution function.

J. Appl. Cryst. (1995). 28, 590

Corrections to Equations for Estimating the Counting-Statistical Errors in Diffraction Stress Measurements

R. A. Winholtz

Synopsis

Two corrections are made to equations for estimating counting-statistical errors in diffraction stress measurements and compared to a Monte Carlo simulation.

J. Appl. Cryst. (1995). 28, 594

Cu(OH)₂: a New Ferroelectric

S. C. Abrahams, J. Ravez, A. Simon, A. Reller and H. R. Oswald

Synopsis

Cu(OH)₂ is predicted to be ferroelectric on the basis of its recently redetermined crystal structure. Calorimetric and dielectric permittivity measurements have verified the prediction, with the predicted T_{c =} 343 K and the measured Curie temperature in the range 325-335 K.

J. Appl. Cryst. (1995). 28, 599

Space-Group Determination of the Orthorhombic Form of NaV₆O₁₁

Y. Kanke, H. Shigematsu, K. Ohshima and K. Kato

Synopsis

The orthorhombic low-temperature form of ferromagnetic NaV₆O₁₁ (T_{C =} 64.2 K) is found to crystallize in the noncentrosymmetric space group Cmc2₁ with no superstructure by an X-ray single-crystal diffraction study performed at 300, 100 and 20 K.

J. Appl. Cryst. (1995). 28, 604

A High-Temperature Furnace for In Situ Small-Angle Neutron Scattering during Ceramic Processing

H. M. Kerch, H. E. Burdette and G. G. Long

Synopsis

The design and operation of a new small-angle neutron scattering furnace are presented. An example drawn from a kinetic study of materials processing is given.

SHORT COMMUNICATIONS

J. Appl. Cryst. (1995). 28, 611

A computer-simulation study of the `white-line effect' in diffraction patterns of mixed charge-transfer salts

T. R. Welberry and N. J. Fox

Synopsis

Computer simulations have been carried out which confirm that the unusual diffraction effect known as the `white-line effect', which is observed in diffraction patterns of some mixed charge-transfer salts, is caused by the pinning of charge-density waves to defects.

J. Appl. Cryst. (1995). 28, 614

Lysozyme solubility in H₂O and D₂O solutions as a function of sodium chloride concentration

I. Broutin, M. Riès-Kautt and A. Ducruix

Synopsis

Results showing increased solubility of lysozyme in H₂O compared to D₂O are presented.

J. Appl. Cryst. (1995). 28, 618

A quantitative measure for the goodness of fit in profile refinements with more than 20 degrees of freedom

J. Ihringer

Synopsis

The novel quality indicator N_igma exhibits the significance level of the result of a least-squares refinement, independent of the number nu of degrees of freedom. For all nu > 20, \vertN_{igma \vert <} 3 indicates conformity of data, weights and model.

J. Appl. Cryst. (1995). 28, 620

On-line processing of pharmaceutical materials using in situ X-ray diffraction

M. L. MacCalman, K. J. Roberts, C. Kerr and B. Hendriksen

Synopsis

In situ X-ray diffraction is applied on-line to optimize crystallization conditions for the preparation of a pharmaceutical compound.

J. Appl. Cryst. (1995). 28, 623

Thermal expansion of caesium halides with the CsCl structure. Erratum

K. Wang and R. Reeber

Synopsis

Correction to J. Appl. Cryst. (1995). 28, 306-313.

COMPUTER PROGRAMS

J. Appl. Cryst. (1995). 28, 624

EDPDB: a multifunctional tool for protein structure analysis

X.-J. Zhang and B. W. Matthews

Synopsis

EDPDB is a multifunctional computer program for the analysis of protein structures, both individually and in crystals.

J. Appl. Cryst. (1995). 28, 630

A program package for preprocessing of two-dimensional detector data

M. Lorenzen, C. Ferrero, O. Diat, C. Riekel and U. Mayerhofer

Synopsis

A program package for interactive preprocessing of two-dimensional detector data has been developed based on CERN's program package PAW. The main use of the package is in analyzing X-ray small-and wide-angle scattering data.

J. Appl. Cryst. (1995). 28, 632

XPLCHK - an extensible program for checking and validating X-PLOR input files

P. B. Laub

Synopsis

The program XPLCHK aids adaptation or development of new X-PLOR input files by scanning these files for common errors and listing parameter assignments.

J. Appl. Cryst. (1995). 28, 635

The Laue Data Module (LDM) - a software development for Laue X-ray diffraction data processing

J. W. Campbell, I. J. Clifton, M. M. Harding and Q. Hao

Synopsis

A Laue Data Module (LDM) and related functions have been defined and implemented in Fortran for use in the initial stages of Laue X-ray diffraction data processing.

J. Appl. Cryst. (1995). 28, 640

GAMATCH - a genetic algorithm-based program for indexing crystal faces

K. Y. Tam and R. G. Compton

Synopsis

A genetic algorithm-based program indexes crystal planes using a set of interplanar angles.

J. Appl. Cryst. (1995). 28, 646

Two computer programs for the automatic analysis of powder diffraction patterns

S. M. Clark

Synopsis

Real-time powder diffraction studies at the Daresbury Laboratory Synchrotron Radiation Source produce many hundreds of powder diffraction patterns every day. Computer programs have been developed for the automatic reduction of these patterns to lists of peak parameters using both multiple peak fitting to selected ranges of each pattern and full pattern fitting.

LABORATORY NOTES

J. Appl. Cryst. (1995). 28, 650

A simple device for increasing the accessibility of reciprocal space in low-temperature area-detector experiments

M. R. Pressprich, B.-J. Fransen, A. Darovsky and P. Coppens

Synopsis

A device is described for the collection of oscillation-method data in two different orientations of a cryostat-mounted sample crystal.

J. Appl. Cryst. (1995). 28, 651

A near-ambient-temperature-control cell for use with synchrotron X-ray powder diffraction

R. J. Cernik, S. R. Craig, K. J. Roberts and J. N. Sherwood

Synopsis

High-resolution powder diffraction has been applied in this study of wax material close to 273 K. Details of the cell construction are given.

J. Appl. Cryst. (1995). 28, 653

An easy technique for making fiber loops for cryocrystallography

L. Blond, S. Pares and R. Kahn

Synopsis

A versatile system for making calibrated loops for cryo-cooling has been designed.

FAST COMMUNICATIONS

J. Appl. Cryst. (1995). 28, 655

Remarks on the geometric parameters in describing diffraction optics of asymmetric Bragg crystals

H.-H. Hung

Synopsis

Darwin's parameter Y defined on the dispersion surface and the associated deviation parameter etaY given by the Takagi-Taupin equations are proposed to characterize the angular deviation from the exact resonance of Bragg diffraction.

Computer Program Abstracts

J. Appl. Cryst. (1995). 28, 659

PARST95 - an update to PARST: a system of Fortran routines for calculating molecular structure parameters from the results of crystal structure analyses

M. Nardelli

Synopsis

An update to PARST, PARST95, is presented.

J. Appl. Cryst.(1995). 28, 660

Notes and News

J. Appl. Cryst.(1995). 28, 660

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Copyright © 1995 International Union of Crystallography