Oxygen partial pressure dependence of electrical conductivity of Sr and Ba β-alumina single crystals

Abstract

Single crystals in Sr and Ba β-alumina solid solution were prepared in the (SrO, BaO)-MgO-Al₂O₃ system by a floating zone method. The electrical conductivities were measured by a.c. impedance spectrometry at 973 K to 1573 K, 0.01 Hz to 10 MHz in air for all specimens and in CO-CO₂ mixed gas for three specimens. All the electrical conductivities for parallel (σ_//) to the cleavage plane are independent of oxygen partial pressure (Po₂), while those for perpendicular to (σ_⊥) the cleavage plane showed a more or less dependence in the low Po₂ range (Po₂ = 10^-4 ∼ 10^-13 Pa).