Oxygen stoichiometry, conductivity and gas sensing properties of BaSnO3

BaSnO3 powder loses a small amount of oxygen in air at high temperatures leading to significant changes in its electronic conductivity. At 1300 degrees C, it has the stoichiometry BaSnO2.9999. The oxygen deficiency can be preserved by quenching to room temperature but the oxygen loss is reversible and reoxidation commences above about 300 degrees C. The n-type conductivity of the quenched material at 300 degrees C, 1 x 10(-5) ohm(-1) cm(-1), is four orders of magnitude higher than that of the same fully oxidised, slow-cooled material. Oxygen-deficient BaSnO3 shows rapid sensitivity to an increase in oxygen partial pressure; it is also sensitive to moisture and then shows proton conductivity.