A-Site and B-Site Charge Orderings in an s-d Level Controlled Perovskite Oxide PbCoO3

Perovskite PbCoO3 synthesized at 12 GPa was found to have an unusual charge distribution of Pb(2+)Pb(3)(4+)Co(2+)2Co(2)(3+)O(12) with charge orderings in both the A and B sites of perovskite ABO(3). 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+Pb34+Co22+Co23+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.