Journal of Applied Crystallography

Contents of Volume 30, Part 4 (1 August 1997)

Cover illustration: A crystal of the protein phosphorylase b flash-cooled to 100 K in a 1 mm-diameter mohair loop prior to collection of X-ray diffraction data. Courtesy of Elspeth Garman and Stephen Lee, University of Oxford.

RESEARCH PAPERS

J. Appl. Cryst. (1997). 30, 421 - 426

Outlier Treatment in Data Merging

R. H. Blessing

Synopsis

Routines employed in the SORTAV program for identifying and downweighting mismeasured outliers in merging multiply measured data sets are described.

J. Appl. Cryst. (1997). 30, 427 - 430

The Use of the Pseudo-Voigt Function in the Variance Method of X-ray Line-Broadening Analysis

F. Sánchez-Bajo and F. L. Cumbrera

Synopsis

This study presents a new technique for calculating the mean crystallite size and root-mean-square strain combining the variance method and the fit of the diffraction profiles by a pseudo-Voigt function.

J. Appl. Cryst. (1997). 30, 431 - 442

Small-Angle Scattering of Interacting Particles. I. Basic Principles of a Global Evaluation Technique

J. Brunner-Popela and O. Glatter

Synopsis

Basic principles of a global evaluation technique for small-angle scattering data of interacting particles are presented.

J. Appl. Cryst. (1997). 30, 443 - 448

Quantitative Texture Analysis from X-ray Diffraction Spectra

Y. D. Wang, L. Zuo, Z. D. Liang, C. Laruelle, A. Vadon and J. J. Heizmann

Synopsis

A method to obtain the orientation distribution function of a polycrystalline material diractly from X-ray diffraction spectra is presented. It uses the maximum-texture-entropy assumption to reduce the diffraction data needed for the quantitative texture analysis.

J. Appl. Cryst. (1997). 30, 449 - 455

Diffraction Peak Displacement in Residual Stress Samples Due to Partial Burial of the Sampling Volume

S. Spooner and X.-L. Wang

Synopsis

Analytic calculation and Monte Carlo simulation of peak-shift effects due to the partial burial of the diffracting gage volume are successful in showing the origins of anomalous peak shifts in neutron strain measurements. The Monte Carlo simulation fits experimental measurements of such shifts in a nickel powder sample.

J. Appl. Cryst. (1997). 30, 456 - 460

The pi/2 Side-Reflection Laue Technique and the New Chart

Y.-H. Park, H.-Y. Yeom, H.-G. Yoon and K.-W. Kim

Synopsis

A new Laue technique, recommended for the real-time observation of structural changes of crystals in an environment of heat or an electric or magnetic field, is presented.

J. Appl. Cryst. (1997). 30, 461 - 466

The Use of Quartz as an Internal Pressure Standard in High-Pressure Crystallography

R. J. Angel, D. R. Allan, R. Miletich and L. W. Finger

Synopsis

The equation of state of quartz has been determined with high precision to a maximum pressure of 8.9 GPa by high-pressure single-crystal diffraction. The new equation of state can be used to determine pressure to a precision of 0.009 GPa at 9 GPa.

J. Appl. Cryst. (1997). 30, 467 - 475

The Quantification of Different Forms of Cristobalite in Devitrified Alumino-Silicate Ceramic Fibres

M. A. Butler and D. J. Dyson

Synopsis

A method for quantifying two forms of alpha-cristobalite in devitrified alumino-silicate fibres is given. The different natures of these two forms of alpha-cristobalite were examined by X-ray diffraction and differential scanning calorimetry.

J. Appl. Cryst. (1997). 30, 476 - 486

Freeze-Trapping Isomorphous Xenon Derivatives of Protein Crystals

O. Sauer, A. Schmidt and C. Kratky

Synopsis

A method is described to diffuse rare gases into protein crystals at elevated pressure and to shock-freeze these crystals without loss of the protein-associated rare gas.

J. Appl. Cryst. (1997). 30, 487 - 493

Two-Dimensional Small-Angle X-ray Scattering Investigation of Stretched Borosilicate Glasses

S. Polizzi, P. Riello, G. Fagherazzi, M. Bark and N. F. Borrelli

Synopsis

Glasses containing Ag(Cl, Br) or Ag needlelike particles are studied by fitting of a two-dimensional model to small-angle X-ray scattering data obtained at the HASYLAB (DESY) synchrotron source.

See also Erratum : J. Appl. Cryst. (1996). 30, 1159.

J. Appl. Cryst. (1997). 30, 495 - 501

Ba₆CoNb₉O₃₀ and Ba₆FeNb₉O₃₀: Two New Tungsten-Bronze-Type Ferroelectrics. Centrosymmetry of Ba_5.2K_0.8U_2.4Nb_7.6O₃₀ at 300 K

M. C. Foster, G. R. Brown, R. M. Nielson and S. C. Abrahams

Synopsis

The calorimetrically and dielectrically observed phase transitions close to 675 K in Ba₆CoNb₉O₃₀ and 590 K in Ba₆FeNb₉O₃₀, together with the dielectric hysteresis that each exhibits, verify the structural prediction that the materials are new ferroelectrics.

See also Erratum: J. Appl. Cryst. (1996). 30, 1159.

J. Appl. Cryst. (1997). 30, 502 - 506

Statistical Analysis and Modelling of Crystallization Outcomes

J. Sedzik and U. Norinder

Synopsis

The work describes a novel application of a recently developed statistical partial least-squares regression technique for the problem of establishing relationships between experimental variables in crystallization trials and the experimental results.

SHORT COMMUNICATIONS

J. Appl. Cryst. (1997). 30, 507 - 509

Equipment for controlling nucleation and tailoring the size of solution-grown single crystals

O. König, P. Rechsteiner, B. Trusch, C. Andreoli and J. Hulliger

Synopsis

Application of local temperature control to DeltaT-grown single crystals allows tailoring of the size.

J. Appl. Cryst. (1997). 30, 510 - 511

Diffraction elastic constants of a cubic polycrystal

R. de Wit

Synopsis

New expressions for the diffraction elastic constants are presented for a cubic polycrystal that is statistically homogeneous, isotropic, and disordered.

LABORATORY NOTES

J. Appl. Cryst. (1997). 30, 512

Crystallization in a chamber furnace

B. Cabric, M. Kovacevic and T. Pavlovic

Synopsis

A model of an air cooler in a laboratory chamber furnace, for simultaneous regulation of different crystallization rates in a series of test tubes with the purpose of obtaining crystals, is presented.

J. Appl. Cryst. (1997). 30, 513

Simple device for mounting crystals for single-crystal diffractometry

R. Vochten, R. Huysmans, N. Blaton and O. M. Peeters

Synopsis

This work describes a micrometric manipulating device for easy mounting of small crystals on a needle along a preferred orientation.

FAST COMMUNICATIONS

J. Appl. Cryst. (1997). 30, 514 - 516

lambda/2 Contamination in charge-coupled-device area-detector data

K. Kirschbaum, A. Martin and A. A. Pinkerton

Synopsis

A method is proposed to estimate and correct for the amount of lambda/2 contamination inherent in area-detector data. The method has been tested on data obtained with a charge-coupled-device detector using Mo Kalpha radiation. For routine data sets, the correction is shown to be insignificant.

J. Appl. Cryst. (1997). 30, 517

Quantitative texture analysis by Rietveld refinement

R. B. Von Dreele

Synopsis

A generalized spherical harmonic description of the texture for polycrystalline materials has been implemented in a multiple phase/multiple data set Rietveld refinement code and is demonstrated with an example.

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