Structural properties of PbVO3 perovskites under hydrostatic pressure conditions up to 10.6 GPa

Abstract

High-pressure synchrotron x-ray powder diffraction experiments were performed on PbVO3 tetragonal perovskite in a diamond anvil cell under hydrostatic pressures of up to 10.6 GPa at room temperature. The compression behavior of the PbVO3 tetragonal phase is highly anisotropic, with the c-axis being the soft direction. A reversible tetragonal to cubic perovskite structural phase transition was observed between 2.7 and 6.4 GPa in compression and below 2.2 GPa in decompression. This transition was accompanied by a large volume collapse of 10.6% at 2.7 GPa, which was mainly due to electronic structural changes of the V4+ ion. The polar pyramidal coordination of the V4+ ion in the tetragonal phase changed to an isotropic octahedral coordination in the cubic phase. Fitting the observed P–V data using the Birch–Murnaghan equation of state with a fixed of 4 yielded a bulk modulus K0 = 61(2) GPa and a volume V0 = 67.4(1) Å3 for the tetragonal phase, and the values of K0 = 155(3) GPa and V0 = 58.67(4) Å3 for the cubic phase. The first-principles calculated results were in good agreement with our experiments.