Pressure Induced Amorphization of Pb²⁺ and Pb⁴⁺ in Perovskite PbFeO₃

Abstract

Perovskite-type oxides have been the subject of intense research due to their various fascinating physical properties stemming from their charge degree of freedom. PbFeO 3 has an unusual Pb 2+ 0.5 Pb 4+ 0.5 Fe 3+ O 3 charge distribution with a long-ranged ordering of Pb 2+ and Pb 4+ and two inequivalent Fe 3+ sites in a perovskite structure. Combined synchrotron X-ray diffraction and Mossbauer spectroscopy revealed a change to an orthorhombic GdFeO 3 structure with a unique Fe 3+ site and randomly distributed Pb 2+ and Pb 4+ at 29.0 GPa, namely, pressure-induced amorphization of Pb 2+ and Pb 4+ . The absence of a charge transfer transition to the Pb 2+ Fe 4+ O 3 phase, which was expected from the comparison with PbCrO 3 and PbCoO 3 , was verified using ab initio density functional theory calculations in the range of 0−70 GPa.