IUCr 1997 Report - Commission on High Pressure

This has been the first full year in the life of the Commission on High Pressure. The year has seen steady progress in establishing the framework of the Commission and clarifying the range of its responsibilities. It was created at the Congress in Seattle without prior preparation, and started out simply as the specialized High Pressure Group of the Commission on Crystallographic Apparatus, with the same membership and no specific new remit. It has seemed wise to take time to consider its new role carefully. Action has now been taken to repair two particularly evident gaps in the wider range of science it would be appropriate for the Commission to cover, by appointing consultants with special expertise in the areas of stress effects (A. K. Singh) and soft matter (S. M. Gruner). The Commission has a Secretary (J. B. Parise) and a Treasurer (W. F. Kuhs). A web page has been set up giving the names and contact addresses of all members and consultants, and details of future meetings.

The principal activity of the Commission has been to support and arrange regular workshops and other meetings. This is judged to be the most important and creative function the Commission can fulfil in a field that is experiencing a period of exceptionally rapid growth and development, particularly through the impact of third-generation synchrotron sources, improved neutron facilities, major improvements in detectors and high-pressure techniques, a steady widening of the range of experimental methods available for high-pressure studies, and a large increase in the capacity for complementary computational work.

The inaugural activity of the Commission was a one-day Symposium on Structural Study under High Pressure using X-rays and Neutrons, at the International Conference on High Pressure Science and Technology (AIRAPT-16) held in Kyoto, Japan, 25 - 29 August 1997. The organizer was O. Shimomura, who reports as follows. The Symposium was a full day of oral sessions, including also short talks on associated poster presentations. The programme aimed to provide an exchange of information on synchrotron and neutron facilities around the world, and the latest high-pressure results obtained using them. Reports on high-pressure research using synchrotron radiation in Europe, the USA and in Japan showed that activities at so-called second-generation sources remain at a remarkably high level despite the impressive power and impact of the new third-generation sources. A review of the current status of neutron scattering under pressure underlined the importance of the continuing development of this complementary technique, and showed the unique contribution it can make. In talks on science topics, the latest results on the structural systematics of semiconductors emphasized the power of image-plate techniques in solving crystal structures; the growingly important experimental and theoretical topic of deviatoric stress was comprehensively reviewed; new techniques for the study of liquid structure, developed at the Photon Factory and ESRF, were presented, based on the combined use of XAFS and density measurements; the value of high-pressure neutron diffraction studies in probing the nature of hydrogen bonding was discussed; promising new applications of the Paris-Edinburgh pressure cell for neutron-scattering studies of phonons at high pressure were illustrated with recent results; and the effectiveness of high-pressure neutron diffraction for studying magnetism was illustrated with new work on rare-earth monopnictides. There was an excellent attendance of some 50 participants throughout, despite the competition of eight other symposia for the overall 600 at the conference.

The Commission's first independent meeting was a three-day Workshop on Crystallography at High Pressure using Synchrotron Radiation: the Next Steps, held at the ESRF in Grenoble, France, 21 - 23 November 1997. The organizer was D. Häusermann, who reports as follows. The availability of very high brilliance radiation at the ESRF since 1993 has had a marked impact on high-pressure science - especially crystallography in extreme conditions of pressure and temperature. The time was right to organize a workshop focusing particularly on synchrotron-based research. 27 scientists representing the main groups active in synchrotron techniques and associated fields around the world gave invited talks on the latest results and developments. The first two sessions were concerned with non-structural techniques, and provided an overview of new work in magnetic dichroism, Mössbauer spectroscopy, inelastic scattering, X-ray absorption, EXAFS on single crystals, and combined spectroscopy and diffraction methods. Two lively sessions followed on the use of laser and resistive heating for work on iron and low-Z systems under extreme P-T conditions. After talks on liquids and large-volume presses, attention was turned to solving and refining structures - with an overview of the complementary use of neutron and X-ray techniques, a presentation of accurate work carried out recently at the ESRF on nitrogen, and a provocative comparison of the respective powers of angle-dispersive and energy-dispersive methods. After a stimulating session on strength, elasticity and kinetics - all `hot' topics, as the extended accompanying discussion demonstrated - the last two sessions concentrated on data collection and analysis in 2-D, developments in 2-D detectors, and future prospects on third-generation sources. The latter session covered highlights of the ESRF programme, the promise of extra photon power at SPring-8, the high-pressure plans for APS, and a `blue skies' forward look at the many new prospects now in view. There were over 80 participants from 18 countries. These included eleven young scientists, from nine different countries, who benefited from support provided by the IUCr. The workshop also benefited from generous financial support from the ESRF, for which the Commission records its gratitude.

During this workshop, the opportunity was taken for two meetings of the Commission. The main business covered included reports on the 1997 meetings, terms of reference, membership, web pages, an address list, and plans for future meetings and other activities. A long and careful discussion of the membership led to the recommendation to appoint two consultants, already reported above. It was agreed to develop and then maintain an up-to-date web page, and to establish as a project for the coming year the compilation of a comprehensive and accurate address list. Detailed discussion of possible plans for 1998 resulted in the choice of a workshop covering the whole breadth of the Commission's range, to be held in the USA late in the year. J. B.Parise and R. J. Hemley agreed to investigate various possibilities. Preliminary consideration of possible options for the 1999 Congress in Glasgow supported a bid for a number of coordinated microsymposia and keynote lectures, similar to the successful workshop within the 1996 Seattle Congress. A proposal from A. Katrusiak to promote high-pressure techniques and make them more widely accessible through a series of schools, starting with one in Erice, Italy, as soon as possible, was strongly supported. He undertook to make contact with the organizers of the Erice schools.

Subsequent developments have led to the choice of Argonne National Laboratory - with its twin facilities of the third-generation synchrotron source, APS, and pulsed neutron source, IPNS - as the venue for the 1998 workshop, to be held 14 - 17 November. First steps have been taken towards organizing a High Pressure School at Erice in 2002 or 2003.

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