Spectroscopic Studies of Sulfite-Based Polyoxometalates at High Temperature and High Pressure

Structural changes occurring within non-conventional Dawson-type [α/β-Mo18O54(SO3)2]4− polyanions in the form of tetrapentylammonium salts were studied by a combination of IR, Raman and visible spectroscopy at high temperature and high pressure. Evidence of the formation of bronze-type materials above 400K and also upon pressurization to 8GPa is presented. This conclusion is suggested to be a general result for polyoxometalate compounds subjected to extreme conditions and it opens opportunities for the design of new materials with interesting optical and electronic properties.