Pressure-induced chemical decomposition of copper orthovanadate (α-Cu3V2O8)

Abstract

The high pressure stability of α-Cu₃V₂O₈ has been investigated via complementary high pressure synchrotron X-ray diffraction experiments and theoretical density functional theory calculations. The results of both experiment and theory are in close agreement. The main result of this work is that α-Cu₃V₂O₈ undergoes a pressure-induced chemical decomposition into CuO and V₂O₅ at a modest pressure of ∼1.35 GPa according to the experimental observations, and at ∼2.45 GPa according to the calculations. The decomposition is investigated with enthalpy calculations and one of the main driving factors is the stability of the octhedral oxygen-coordination of the metal atoms in the decompositon products. Additionally, we determine the bulk modulus of α-Cu₃V₂O₈ to be the lowest of all known vanadates, at 52(2) GPa, due to its crystal structure, and determine the corresponding isothermal compressibility tensor.