Physical properties and electronic structure of a new barium titanate suboxide Ba1+δTi13-δO12 (δ = 0.11).

The structure, transport, thermodynamic properties, x-ray absorption spectra (XAS), and electronic structure of a new barium titanate suboxide, Ba_1+δTi_13-δO₁₂ (δ = 0.11), are reported. It is a paramagnetic poor metal with hole carriers dominating the transport. Fermi liquid behavior appears at low temperature. The oxidization state of Ti obtained by the XAS is consistent with the metallic Ti²⁺ state. Local density approximation band structure calculations reveal the material is near the Van Hove singularity. The pseudogap behavior in the Ti-d band and the strong hybridization between the Ti-d and O-p orbitals reflect the characteristics of the building blocks of the Ti₁₃ semi-cluster and the TiO₄ quasi-squares, respectively. [ABSTRACT FROM AUTHOR]