Highly conductive oxides, CeVO4, Ce1-xMxVO4-0.5x(M= Ca, Sr, Pb) and Ce1-yBiyVO4, with zircon-type structure prepared by solid-state reaction in air

The zircon-type phases, CeVO4, Ce1-xMxVO4-0.5x (0 less than or equal to x less than or equal to 0.41 for M = Ca, 0 less than or equal to x less than or equal to 0.21 for M = Sr, and 0 less than or equal to x less than or equal to 0.1 for M = Pb) and Ce1-yBiyVO4 (0 less than or equal to y less than or equal to 0.68), have been prepared in air by heating the stoichiometric mixture of CeO2, V2O5, CaCO3, SrCO3, PbO, and Bi2O3. During solid-state reaction, the spontaneous reduction of Ce(IV) to Ce(III) begins above 500 degrees C and proceeds rapidly at about 666 degrees C in conjunction with the melting of V2O5. All of these phases present high electrical conduction. In particular, the phases Ce1-xMxVO4-0.5x (M = Ca, Sr, and Pb) show excellently high values. The compound CeVO4 is characterized as a p-type semiconductor by the Seebeck effect. (C) 2000 Academic Press.