Original paper

Electronic state of oxygen in oxide minerals: an XAS study on the influence of cationic environment

Figueiredo, Maria Ondina; Mirão, José

Abstract

The results are reported here of a XAS study of the O K-edge in oxide minerals, focused on triangular (C2v site symmetry) and tetrahedral (Td, C2v and C1) environments involving diverse coordinating cations within four crystal structure types: rutile-type (rutile, pyrolusite and cassiterite), fluorite-type (thorianite), spinel-type (spinel s.s.) and garnet-type (andradite). Full multiple-scattering calculations are compared to actual spectra with the aim of interpreting pre-edge peaks and post-edge features. Comments are presented on the role of combinations between O 2p and metal valence bands. It is concluded that the details and the energy of the O K-edge are influenced by the electronic state and coordination geometry of the surrounding cations in connection with the site symmetry constraints of the coordinated oxygen atoms within the host crystal structure.

Keywords

oxygenxasmultiple-scatteringmineralsbondingk-edge