A-Site and B-Site Charge Orderings in an s-d Level Controlled Perovskite Oxide PbCoO 3 .

Perovskite PbCoO3 synthesized at 12 GPa was found to have an unusual charge distribution of Pb2+ Pb4+ 3 Co2+ 2 Co3+ 2 O12 with charge orderings in both the A and B sites of perovskite ABO3 . Comprehensive studies using density functional theory (DFT) calculation, electron diffraction (ED), synchrotron X-ray diffraction (SXRD), neutron powder diffraction (NPD), hard X-ray photoemission spectroscopy (HAXPES), soft X-ray absorption spectroscopy (XAS), and measurements of specific heat as well as magnetic and electrical properties provide evidence of lead ion and cobalt ion charge ordering leading to Pb2+ Pb4+ 3 Co2+ 2 Co3+ 2 O12 quadruple perovskite structure. It is shown that the average valence distribution of Pb3.5+ Co2.5+ O3 between Pb3+ Cr3+ O3 and Pb4+ Ni2+ O3 can be stabilized by tuning the energy levels of Pb 6s and transition metal 3d orbitals.