Crystal Structures and Electronic States of High-Pressure-Synthesized (1-x)PbVO₃-xBiCrO₃ Solid Solutions

Abstract

Electronic states in solid-solution transition metal oxides may differ from those in their parent compounds, and this results in interesting electronic properties. In this study, the valence states and electronic properties of solid solutions of (1 − x)PbVO 3 − xBiCrO 3 are reported. The solid solutions are successfully synthesized under high-pressure and high-temperature conditions of 5 GPa or 7 GPa and 1273 K, respectively. A change in the crystal structure from centrosymmetric monoclinic (C2/c), as in BiCrO 3 , to polar tetragonal (P4mm), as in PbVO 3 , is observed. A tetragonal-to-cubic phase transition, which results in a negative thermal expansion, was observed in 7/8PbVO 3 -1/8BiCrO 3 at approximately 700 K. X-ray absorption spectroscopy and magnetic studies reveal that the Cr and V atoms are in the valence states 3+ and 4+, respectively, which are the same as those of the parent compounds. Thus, it was concluded that the valence state of V 4+ /Cr 3+ and the electron localization in the (1 − x)PbVO 3 − xBiCrO 3 solid solutions are considerably robust.