Synthesis of New Materials Under High Pressure Conditions.
Résumé
High pressures appear an important tool for the synthesis of new materials. Different routes are possible. -Through volume contraction, new phases can be prepared (ΔV<0). -The stabilization of thermally unstable materials can open the investigation of new diagrams. -The preparation of the highest oxidation states of transition metals through the development of high oxygen pressures is an important challenge for understanding the correlations between the covalency of the M-O bonds and the resulting physico-chemical properties of the corresponding oxides. -Recently, the development of solvothermal reactions has allowed the synthesis of new materials (as phyllosiloxides) and the development of original processes. Several examples will be selected for illustrating the different abilities of high pressure synthesis through the different routes described. A discussion will propose, for the future, some routes for developing pressures in Materials Science.