Cristallogenèse de matériaux aux propriétés physiques originales sous conditions extrêmes de pression et de température – CrystalPress

Title: Crystal growth of materials with original physical properties in extreme conditions of pressure and temperature: from in-situ characterization of mechanisms involved to the understanding and full control of elaborated compounds The 'CrystalPress' project concerns the study of crystal growth under high pressure and high temperature. This domain of material science is still little investigated because of experimental difficulties, yet it is undoubtedly a very promising subject for future discoveries. The exploration or re-exploration of new and previously studied phase diagrams at high pressure and high temperature (HP-HT) is an important tool for the discovery of new interesting phases in the future. In-situ HP-HT studies are so far rather scarce; they are limited to experiments in synchrotron sources (or neutron sources) or sometimes HP-HT laboratory syntheses with post mortem (or ex-situ) analysis. Therefore in-situ characterization in laboratory experiments would be a very precious research tool. This project is proposed by Pierre Toulemonde from SPM-CE group (MCMF Dept., Institut Néel, Grenoble); he is 'Maître de Conferences' (5th year) at Joseph Fourier University, Grenoble, since September 2006 after 4 years in Claude-Bernard University (Lyon I). This project is reinforced by the recognized competences of chemists (C. Darie and P. Strobel), physicists (P. Bordet), engineers (C. Goujon, Luc Ortega, Alain Prat) and technicians (Rémy Bruyère and Murielle Legendre) in the SPM-CE team and in the instrumentation group of MCMF department. It includes also as external partner Mohamed Mezouar, responsible of ID27 high-pressure beamline at ESRF, Grenoble. The basic objectives of this project is the study of formation and crystal growth conditions of materials with interesting intrinsic physical properties by in-situ characterization at HP-HT, and their elaboration in single crystal form in large volume presses. The success of this project is linked to 2 specific high pressure apparatus: the Paris-Edinburgh cell and the already available Conac cell. This project is built in two parts: 1. scientific part: search and in-situ study (under HP-HT) of new compounds with original physical properties by more systematic investigation of P,T phase diagrams The typical compounds will be: (i) high pressure oxide phases which interest to the french physics community and particularly the physicists of Grenoble: multiferroic compounds (ex : BiMnO3, BiCrO3), magnetic frustrated compounds (GeCu2O4), new superconductors (ii) new hypothetical compounds with spinel (LiCr2O4, GeCu2O4 et SiM2O4) or pyrochlore structure (M2Si2O7, M2Nb2O7, pyrochlores based on noble metals : Rh, Os, Re, Ru) In all cases, it is important to focus on obtaining single crystals, to allow detailed and comprehensive studies of physical properties In a second stage, this part of the project could be extended to the study of other classes of materials: intermetallics, covalent compounds etc. 2. instrumental part, by 2 routes: a) the installation in the MCMF department of a Paris-Edinburgh (PE) cell coupled to a laboratory x-ray generator with an image plate detector b) the development of in-situ measurements (thermdynamics measurements by thermocouple) in the Conac cell already installed in our laboratory The financial aid asked in this project is mostly devoted to the purchase of a PE cell with complete P and T regulation system, anvil pairs for PE and Conac cells, various parts for the two HP systems, special thermocouples required for in-situ thermodynamics measurements in the Conac cell. Also included in the budget is a financial aid for the recruitement of a post-doctoral student who will work in the different high pressure systems of the project. In conclusion, this project fits very well in the scientific topics developed in the SPM-CE group of the laboratory; it should contribute to give young scientists means to develop an original research tool. It will contribute to make Grenoble as a pole of excellence of the french research in the topic of elaboration at HP-HT of new materials, in particular in their single crystal form, and in their related in-situ studies.