ELECTRICAL AND OPTICAL-PROPERTIES OF AVO(4) (A=FE,CR,AL) COMPOUNDS

Measurements of the electrical resistivity, the Seebeck effect and the UV/VIS absorption were carried out for samples of AVO(4) (A = Fe, Cr, Al) compounds. It was observed that: 1) chromium and aluminum vanadat es are insulators at room temperature and they have p and n-type elect rical conductivity at higher temperatures, respectively, 2) the shift of the absorption edge to lower wavelengths in iron and aluminum vanad ates and to higher ones in chromium vanadate in comparison with their constituents is connected with the type of the crystal structure, 3) t he charge transport occurs via anion-deficient centers in iron and alu minum vanadates and via cation-deficient centers in chromium vanadate.