Electronic Structure of Sr2AlNbO6: Dielectric and X-ray Photoemission Spectroscopy Study

Abstract

The dielectric property and the electronic structure of double perovskite oxide strontium aluminium niobate, Sr2AlNbO6 (SAN), synthesised by a solid state reaction technique are investigated. The Rietveld refinement of the X-ray diffraction data of the sample shows the cubic phase with the Fm3m structure (lattice parameter, a ¼ 7:7789A˚ ). The compound shows significant frequency dispersion in its dielectric properties. The Cole– Cole model is used to study the dielectric relaxation of SAN. The scaling behavior of loss tangent suggests that the relaxation describes the same mechanism at various temperatures. The electronic structure of SAN is studied by the first principles full potential linearized augmented plane wave method. Its valence band consists mainly of the O 2p states hybridised with the Nb 4d states. The calculated density of states is used to compare the valence band X-ray photoemission spectra of the sample.