Electrical and optical properties of AVO4(A = Fe, Cr, Al) compounds

Measurements of the electrical resistivity, the Seebeck effect and the UV/VIS absorption were carried out for samples of AVO4 (A = Fe, Cr, Al) compounds. It was observed that: 1) chromium and aluminum vanadates are insulators at room temperature and they have p and n-type electrical conductivity at higher temperatures, respectively, 2) the shift of the absorption edge to lower wavelengths in iron and aluminum vanadates and to higher ones in chromium vanadate in comparison with their constituents is connected with the type of the crystal structure, 3) the charge transport occurs via anion-deficient centers in iron and aluminum vanadates and via cation-deficient centers in chromium vanadate.