A new way to make solid state chemistry: Spark plasma synthesis of copper or silver vanadium oxide bronzes

摘要

The spark plasma sintering technique for various materials, oxides, nitrides, carbides, metals, composites, etc. is undergoing a rapid development following pioneering work in Japan. Here, the technique is used to create a new route to make solid state chemistry. The M-V-O system (M = Cu, Ag, Zn) was selected and direct interaction of M with vanadium pentoxide was performed. Remarkable syntheses have been achieved within minutes, paving the way for new materials. The M_xV_2O_5 phases formed with Cu and Ag belong to the mixed valence metal-vanadium oxide bronzes whose structures and electric properties are of interest for applications as electrode materials in lithium batteries. Their formation may also be used as a model for further investigations in order to follow the diffusion mechanisms of atoms in solids and to get a better understanding of the SPS process. In this experiment M atoms penetrate micro-crystals of V_2O_5 oxide at a high speed, shearing their crystal network and rebuilding simultaneously in the mean time the crystal structure of the prototype structures beta, beta', epsilon or delta M_xV_2O_5.