Electronic transitions in the VBO3 single crystal at high pressures

Abstract

Optical absorption spectra of single crystals of the ferromagnetic semiconductor VBO3 are studied at high pressures up to 70 GPa achieved in a diamond-anvil cell. An electronic transition accompanied by sharp changes in the optical parameters and a decrease in the optical gap from E 0 = 3.02 eV to 2.25 eV is found at the pressure P C ∼ 30 GPa. The gap does not disappear in the high-pressure phase and its value becomes typical of semiconductors. This is indicative of a semiconductor-semiconductor transition. The transition to the metallic state may occur at the critical pressure P met ≈ 290 GPa.