Oxygen stoichiometry, conductivity and gas sensing properties of BaSnO3

Abstract

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 BaSnO_2.9999. 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.