The electronic structure of the mixed valence compound Pb3O4

Ab initio self-consistent calculations of the electronic structure of Pb3O4 are presented. The calculations show that Pb3O4 is a semiconductor. The calculated bandgap of 1.1 eV is smaller than the observed gap of 2.1-2.2 eV. The calculations show strong hybridization between Pb(6s) and O(2p) states. For one type of lead atom, this leads to a distribution of Pb(6s) states over two occupied energy bands, similar to the situation in PbO. For the other type of lead atom in Pb3O4 the Pb(6s) states are distributed over an occupied and an unoccupied band, similar to the situation in beta-PbO2. This clearly demonstrates that Pb3O4 is a mixed valence compound, i.e. Pb(II)(2)Pb(IV)O-4. According to the calculations, the conductivity of p-type Pb3O4 is due to holes in a Pb(II)(6s) valence band and the conductivity in n-type Pb3O4 is due to electrons in a Pb(IV)(6s) conduction band. (C) 1997 Elsevier Science Ltd.