Differential scanning calorimetry, X-ray diffraction, and alternating-current and direct-current conductivity methods were used to show that melt-grown samples had a tetragonal structure at room temperature. It was also shown that other phases existed at high temperatures. All of the samples exhibited conductive properties which suggested the occurrence of anionic vacancy diffusion. The room-temperature conductivity was equal to 2.62 x 10-9S/cm.

T.A.Kuku, A.M.Salau: Solid State Ionics, 1987, 25[1], 1-7