Report on the International Workshop

Crystallography at high pressures 2006

organized by the Commission on High Pressure of the International Union of Crystallography and the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research,

Dubna, Russia, September 28 – October 1, 2006

The International Workshop on Crystallography at High Pressure - 2006 followed the sequence of workshops organized on behalf of the IUCr Commission on High Pressure (ESRF, Grenoble, 1997; Argonne, USA, 1998; SPring-8, Japan, 2000; Orsay, France, 2001; Berkeley, USA, 2003; Saskatoon, Canada 2004) and also the sequence of meetings on Neutron Scattering at High Pressure organized by the FLNP JINR (NSHP-I in 1994 and NSHP-II in 1999, Dubna, Russia).

The Workshop attracted nearly 80 scientists from 10 countries. Its scientific programme contained 10 oral sessions and 2 poster sessions, covering the full range of scientific activities of the Commission on High Pressure. During three and half days, 30 oral and 35 poster presentations (including 9 poster orals) were made. A number of invited oral talks and poster orals were given by young scientists.

The participants stayed at the hotel “Dubna” and have enjoyed not only scientific sessions held in the International Conference Hall, but also walking along the picturesque banks of Volga river.

After the Welcome address of A.M.Balagurov, A.V.Belushkin presented an overview of JINR, FLNP and the pulsed reactor IBR-2. This introduction followed by the session “Simple Elements”. K.Takemura (NIMS, Japan) discussed the phase diagram of mercury and distinctions in the behavior of this unusual metal with other metallic elements. E.G.Maksimov (LPI RAS, Russia) reviewed the experimental and theoretical investigations of simple metals under pressure, giving special insight into the cases of highly compressed Li and Ca with a focus on their electrophysical properties. M.Hanfland (ESRF, France) concentrated on the structural phase transitions in Li, Na and molecular hydrogen in over 100 GPa range. J.Kohanoff (University of Belfast, UK) presented a new methodology for theoretical studies of incommensurately modulated phases, which appear at high pressures in some alkali elements and group II, V, VI and VII elements, as well as in some transition metals.

The next session “Molecular Solids” started with a talk by S.Scandolo (ICTP, Italy) on the experimental and first-principles-based theoretical investigations of the extended amorphous form of carbon dioxide. I.N.Goncharenko (LLB, France) highlighted the progress on powder and single crystal neutron diffraction experiments under very high pressures up to 40 GPa, illustrated by investigations of magnetic phase transitions in solid oxygen and broken symmetry phase transition in solid deuterium. M.I.Eremets (MPI fur Chemie, Germany) discussed the transformation of molecular nitrogen to single bonded polymeric nitrogen at megabar pressures.
The second day started with the session “Physical Properties and Magnetic Structures”. The complexity of pressure-induced magnetic phenomena in geometrically frustrated pyrochlores, with interesting examples of spin liquid, spin ice and spin glass states, was shown in the talk of I.Mirebeau (LLB, France). D.P.Kozlenko (JINR, Russia) overviewed the pressure-induced magnetic phase transitions in manganites and provided comparison with theoretical calculations. Y.Yao (University of Saskatchewan, Canada) presented the theoretical calculations on structure and properties of high pressure molecular hydrides SiH₄ and SnH₄, predicting surprisingly high superconducting critical temperatures above 45-80 K in the pressure range 60-150 GPa.

The following session “Materials Science and High Pressure Synthesis” was opened by J.E.Lowther (University of Witwatersrand, South Africa) discussed the advances in theoretical modeling of potentially important superhard materials. This talk was nicely amplified by experimental results on the synthesis of new superhard phases in B-C system, presented by V.L.Solozhenko (LPMTM-CNRS, France). E.Gregoryanz (University of Edinburgh, UK) and A.Belik (NIMS, Japan) have demonstrated very promising opportunities for the high pressure synthesis of novel technologically important materials, such as noble metal nitrides which can be alternative to traditional superhard materials, as well as ferroelectric and multiferroic oxide materials.

In the “Mineral Physics and geophysics” session, I.Yu.Kantor (BGI, Germany) discussed the complex behavior of the (Mg,Fe)O system under pressure, the most abundant non-silicate oxide in the Earth, and emphasized the importance of the interplay between structural, magnetic and electronic properties. Y.S.Genshaft (IPE RAS, Russia) and T.I.Ivankina (JINR, Russia) overviewed investigations of the physical and chemical properties and processes of texture formation of minerals from deep Earth’s litosphere, in particular, from Kola Superdeep Borehole (Kola peninsula, Russia).

The special session of the meeting was dedicated to technical developments. Y. Le Godec (PMD IMPMC, Universite P&M Curie, France) presented a new high pressure set-up for in situ angle dispersive X-ray diffraction studies in the extended pressure and temperature ranges. Y.Wang (GSECARS, USA) introduced audience to details of the new step-scan diffraction technique for collection of angle dispersive data using solid state detector and white synchrotron radiation. Y.Zhao (LANL, USA) reviewed scientific achievements and technological advances of neutron diffraction at high pressures and temperatures at LANSCE. The present capabilities of the inelastic X-ray scattering for investigations of phonons under high pressure were illustrated in the talk of M.Krisch (ESRF, France). B.P.Tolochko (INP SO RAS, Russia) described the synchrotron radiation beamline setup for in situ investigation of extreme condition of matter under shock and detonation waves compression with nanosecond resolution and overviewed recent scientific investigations.

In the session “Organic Materials” E.V.Boldyreva (NSU, Russia) reviewed high pressure studies of pharmaceutical materials. M.Podsiadlo (AMU, Poland) discussed the pressure-freezing of halogenated methanes.

During the last day of the meeting, sessions “Liquids and Amorphous Materials” and “Carbon and Nano materials” were held. New pressure-induced phenomena in liquid and glassy oxides, halogenides and chalcogenides were illustrated by V.V.Brazhkin (HPPI RAS, Russia). T.Hattori (Spring-8, Japan) provided evidence for a role of the topological disorder in the pressure-induced structural changes of covalent, ionic and metallic liquids. M.Guthrie (University of Edinburgh, UK) reported on the disorder effects in ice under pressure. A.Correa (LLNL, USA) discussed the phase diagram and electronic properties of carbon at very high pressures and temperatures, obtained from first principles calculations. The effects of pressure, radiation and temperature on carbon and carbon-based materials were overviewed by V.A.Somenkov (RRC “Kurchatov Institute”, Russia).

During the guided excursion to the IBR-2 high flux pulsed reactor facility, participants were able to familiarize themselves with capabilities for neutron scattering investigations under high pressure, available at FLNP JINR.

Meeting finances

Participants fees: 6500 USD
FLNP JINR: 10000 USD
IUCr: 5000 USD
Russian Federal Agency for Science and Innovations: 3700 USD
Russian Foundation for Basic Research: 4500 USD
Total: 29700 USD

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