IUCr 1994 Report - Commission on Powder Diffraction

During 1994, the Commission on Powder Diffraction (CPD) was involved in the organization of two very successful powder diffraction Meetings in Russia and South Africa, and assisted with the preparation for three Meetings scheduled for 1995 in England and Slovakia. Planning also continued for the CPD's involvement in the IUCr Congress in Seattle in 1996, together with the associated Satellite Meeting on Powder Diffraction in Denver. The results of Part II of the Rietveld Refinement Round Robin were published, and a grant was provided in support of the continued development of the World Directory of Powder Diffraction Programs. Direct communication with powder diffractionists continued with the issuing of two further CPD Newsletters in April and October.

The International Workshop on Advanced Powder Diffraction Techniques in Mineral and Materials Processing was held in Pretoria, South Africa, in October 1994, and was co-organized by the Crystallographic Society and Mineralogical Association of South Africa. CPD member Dr Lynne McCusker was an invited speaker and served as Chairman of the Scientific Programme Committee, member Dr Ian Langford was also an invited speaker, while CPD Chairman Dr Rod Hill contributed to the Programme Committee. The Meeting was an outstanding success, with participants from many countries in Southern Africa gaining valuable experience from a series of carefully crafted lectures, tutorials and hands-on Workshop sessions on all aspects of powder diffraction analysis, including sessions presented by the ICDD.

The Intenational Conference on Powder Diffraction and Crystal Chemistry was held in St Petersburg, Russia, in July 1994, co-organized by the Russian Association of Powder Crystallography, the Department of Crystallography of St Petersburg University and the CPD. Lectures and posters were presented to 165 participants from 20 countries, including a Workshop run by the ICDD, and a 211-page book of abstracts was produced. St Petersburg's strong past and current links with crystallography, dating from Federov's discovery of the 230 space groups in 1890, along with its geographic beauty, provided a very appropriate and delightful backdrop for a most successful Conference.

The CPD lent its support to the EPDIC IV Meeting in Chester in July 1995 and the International Conference on X-ray Powder Diffraction Analysis of Size/Strain, Macrostress and Texture in Slovakia in August 1995; CPD member Dr Jaroslav Fiala and the CPD Chairman served on the Programme Committees for both of these Meetings, Dr Fiala as Chairman for the Slovakia Meeting. Preparations for a CPD-organized Microsymposium on powder diffraction at the Seattle Congress commenced, including nominations for a session Chairman and possible topics. Similarly, arrangements were put in place for a Satellite Meeting on Powder Diffraction to be held in Denver in August 1996, in conjunction with the 45th Meeting of the Denver X-ray Conference.

Two CPD Newsletters were issued in April and October, edited by CPD members Professor Deane Smith of the Pennsylvania State University, USA, and Dr Bob Cernik of Daresbury Laboratory, England, respectively. Feature articles included the explanation, establishment and use of crystallographic news groups on the world-wide Internet (by Lachlan Cranswick of CSIRO in Melbourne, Australia), use of synchrotron diffraction information from single powder grains for structure solution prior to Rietveld refinement using bulk powder diffraction data (by Bob Cernik of Daresbury Laboratory, England), description and use of CIF for powder diffraction (by Brian Toby, Terrytown, USA), introduction to the SPring-8 project (by Hideo Toraya, Nagoya, Japan) and the new high-resolution neutron powder diffractometer at the high-flux isotope reactor, Oak Ridge, USA (by Brian Chakoumakos, Oak Ridge National Laboratory, USA).

The CPD remained active in the execution of its existing projects and in the initiation of new ones. Part II of the Rietveld Refinement Round Robin Project was published in J. Appl. Cryst. (1994), 27, 802-844. This part of the project provided outcomes of the analysis of Rietveld refinements of the monoclinic zirconia crystal structure based on X-ray and neutron powder diffraction data collected on a `standard' sample with a wide spectrum of instruments located in 12 countries around the world. Work on Part III commenced during the year - this part will focus on a multivariate analysis of the results obtained from the zirconia refinements.

The CPD confirmed its on-going support for the World Directory of Powder Diffraction Programs, co-produced by CPD member Professor Deane Smith from the USA and Dr Syb Gorter from The Netherlands, through the provision of a grant for the purchase of computer hardware. Organization of a new round robin project on Phase Quantification by Diffraction Methods, coordinated by Deane Smith, continued during the year with a call for expressions of interest and suggestions for the type of tests and samples that might be used. Also, arrangements continued for a survey of methods and models in use for the determination of crystallite size and microstrain from powder diffraction data under the auspices of a Task Group co-chaired by Dr Jaroslav Fiala and Professor Bob Snyder of the USA.

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