Bismuth and vanadate activators in BiMVO5 (M=Ca, Mg, Cd) phases: Structural, electronic and optical specificities

Abstract

In the BiMVO5 series, only three representatives were found to show photoluminescence (PL) at room temperature, namely the compounds with M = Mg, Ca and Cd. Their optical properties are complex, but understood on the basis of the calculated electronic structures. Indeed, two antagonist behaviors are distinguishable by the existence (Mg, Ca) or not (Cd) of a broad area (∼0.9 eV above the bottom of the conduction band) allowing for non-radiative electronic transitions at room temperature. In spite of the existence of the two structural polytypes of a cis- (Ca, Cd) and trans-like (Mg) connectivity to the oxygen bridges, the structural topology is not directly related to the two contrasted PL processes. It seems rather correlated to the degree of the distortion of the VO43− tetrahedra and the splitting of the 3d levels that favor a violation of forbidden transitions.