Pressure-induced amorphization and decomposition in ZrV2O7:: A Raman spectroscopic study

In situ high-pressure Raman spectroscopic studies on ZrV2O7 suggest growth of disorder in the high-pressure orthorhombic phase, inferred from the excessive broadening of Raman peaks, and the sample gradually turns amorphous above 4 GPa. The samples pressure cycled from 10 GPa exhibit irreversible amorphization. On the other hand, the spectrum of the sample pressure cycled from 4 GPa is found to have all the characteristic peaks of V2O5 indicating a possible decomposition of the compound into a mixture of simple oxides. A partial decomposition is indeed confirmed from the x-ray-diffraction pattern of the recovered sample. A large decrease of the intensity of the VO4 tetrahedral stretching modes is consistent with the possible coordination change of vanadium, from fourfold in ZrV2O7 to fivefold in V2O5. Nucleation of nano-/poorly crystallized grains of the daughter phase even at ambient temperature is understood as due to the existence of the fivefold coordinated crystalline phase, V2O5.