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 °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 °C. The n-type conductivity of the quenched material at 300 °C, 1 × 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.