IUCr 1999 Triennial Report - Commission on Powder Diffraction

The Commission had an ambitious programme of events and projects during the triennium. The mailing list for the Newsletter has expanded from just over 800 to 1,346 indicating strong and expanding worldwide interest. The Newsletter has become almost self funding from advertising revenue. The Commission has recommended support for a large number of workshops and schools to encourage worldwide teaching of powder methods. It has recommended that the powder community be re-integrated with the body of the crystallographic community for the Glasgow Congress. It was felt that the subject had made such progress in the last decade that it was now appropriate that this achievement be recognised by the mainstream crystallographic community. Led by Commission member L.B. McCusker on the Glasgow Programme Committee, the whole Commission has worked very hard on the programme for Glasgow. A major point of emphasis here was the collaboration with other Commissions. This has been especially successful with the Commissions on Electron Diffraction, XAFS, Small-Angle Scattering and Synchrotron Radiation (via a satellite meeting). The result has been an unprecedented expansion in the microsymposia dedicated to materials science and powder methods. The establishment of the ECA and associated Special Interest Groups (SIGs) has raised interesting new ways of interacting with the European powder community. A committee has been formed to represent the EPDIC series of meetings. At least four Commission members, including the Chair, now sit on that committee to ensure maximum co-operation and dialogue between EPDIC and the Commission.

Meetings/workshops/schools

The largest meetings covering the areas of interest for the Commission were the European Powder Diffraction Conferences held in Parma, Italy, and Budapest, Hungary. These were excellent meetings organised by G. Artioli and T. Ungar. Both conferences covered structure solution; refinement; QPA; in situ kinetics; catalysis; disordered structures; instruments; size/strain; accuracy; thin films and general materials. The focus of the Budapest meeting was more strongly concentrated on practical applications of the method. The Commission held business meetings in Parma (1995) and Budapest (1998). There was Commission involvement in the 17th Conference on Applied Crystallography and the 3rd Rietveld Summer School organised by D. Stroz (1997) and at the workshop to discuss the possibility of a Spanish powder beamline at the ESRF (1998). Commission member S. Sen-Gupta organised a meeting in Calcutta, India (1998), which included a wide variety of presentations, mostly practical. This meeting was very popular and included the President of the IUCr among the attendees. Shao Fan Lin obtained funding for visiting speakers to a powder workshop to be held in Kunming, People's Republic of China (1999). The Commission was also represented at the Stockholm School on Electron and Powder Diffraction (1998) organised by S. Hovmöller. Throughout the triennium there was a significant number of people participating in Commission events and the Denver meetings. In 1996, M. Delgago organised a powder diffraction course in Merida, Venezuela, and there was a School on Polycrystalline Diffraction in Frascati, Italy (1996), organised by G. Cappuccio.

Projects

Quantitative phase analysis

Four samples of carefully constituted multiple composition have been distributed to those people who volunteered for the study. All the results are back and have been analysed. The participants have all been informed of the real composition of the test samples. The original chemical specification has changed slightly since the original specification and is now better defined. The samples are (1) corundum + zincite + fluorite; (2), as (1) but with preferred orientation and brucite; (3), as (1) but with amorphous glass; (4) corundum + magnetite + zircon. Thanks are due to I.C. Madsen particularly but also to Commission consultant R.J. Hill, and to Commission member D.K. Smith. I.C. Madsen will present the results of the study in full at the Glasgow Congress.

Rietveld guidelines

Commission member L.B. McCusker has led the project to publish advice and guidelines for Rietveld refinement [J. Appl. Cryst. (1999). 32, 36—50]. The paper has the endorsement of the Commission and we hope that it will spread better working practices amongst the powder community. This was felt to be necessary after the results of the first Commission round robin were published by Hill & Cranswick [J. Appl. Cryst. (1994). 27, 802—844]. A copy has been distributed with the Spring Newsletter.

Industrial application notes

Commission member P. Scardi has begun research into the possibility of the Commission making further inroads towards industrial application notes. The aim would be to publish good practice in certain common industrial situations in a variety of languages. This project is not finished but has attracted a good deal of interest.

Software and the web

The Commission web site has been used to direct interested parties to freely available software in powder diffraction. Links now exist to the CCP14 and programme exchange banks. Further links on the Commission web site can easily lead the reader to all the most readily accessible crystallography sites in the world. Mirror sites have been set up in Australia and the USA.

Newsletters

There have been five Newsletters published in this period edited by Commission members L.B. McCusker, R. Delhez, P. Scardi, S. Sen-Gupta and guest editor L.M.D. Cranswick. All editions have appeared on the web (http://www.iucr.org/iucr-top/comm/cpd/index.html).

R.J. Cernik, Chair

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Updated 6th December 1999