Local Structures in High Pressure Phases of V₂O₅

The high-pressure behavior of layered V 2 O 5 is investigated using in situ Raman spectroscopy in a diamond anvil cell. Upon compression, the mode associated with the vanadyl V O double bond at 997 cm - 1 softens and vanishes at about 10 GPa. Above 7 GPa, additional modes appear in the V−O stretching region, at lower wavenumbers than the V O stretching oscillation. Such a behavior is interpreted as a pressure-induced five-to-six coordination change around the V 5+ cations, leading to a three-dimensional V 2 O 5 lattice. Upon decompression, intermediate phases are recovered.