A new O-deficient Aurivillius-like phase was synthesized, and its ionic conductivity was measured by using alternating current impedance spectroscopy. It was found that the O-ion conductor exhibited a discontinuity in the Arrhenius plots of the ionic conductivity. A phase transition, which was confirmed by means of differential thermal analysis, was consistent with an O vacancy order-disorder transition. At 900C, the conductivity was 0.031S/cm.

K.R.Kendall, J.K.Thomas, H.C.Zur Loye: Solid State Ionics, 1994, 70-71, 221-4