Quantum-Chemical Calculation of the Electronic Structure and Ionic Conductivity of Lead Hexaferrite with a Magnetoplumbite Structure

The ab initio linear muffin-tin orbital method in a tight binding approximation (LMTO-TB) and semiempirical extended Hückel theory (EHT) were used to study the electronic structure, chemical binding, and ion conductivity of hexaferrite PbFe₁₂O₁₉. The analysis of chemical bonds showed that Fe–O interactions play the dominant role in the chemical bonding in hexagonal ferrites, the covalent component of the Pb–O bond being insignificant. The metallic Fe–Fe bonds have been found. The predicted increased mobility of Pb²⁺ ions in the structure of magnetoplumbite agrees well with the experimental parameters of lead diffusion and ion–electron conductivity in PbFe₁₂O₁₉. The mechanism of migration of lead ions in the structure of the hexaferrite is discussed.