Ionic and electronic conductivity measurements were performed on polycrystalline Ca2+-conducting β"-alumina. Two Ca2+ conductivity regions were found, such that the activation energy was equal to 13.1kcal/mol at temperatures ranging from 340 to 450C, and was equal to 9.1kcal/mol at higher temperatures. It was suggested that the higher activation energy might reflect a predominance of grain-boundary conductivity in the lower temperature region. The diffusivity of Ca2+ was found to be of the order of 10-8 cm2/s at 400C, and about 10-6cm2/s at 630C.

K.W.Semkow, A.F.Sammells: Journal of the Electrochemical Society, 1988, 135[1], 244-7

Table 15

Diffusion of H3O in Na/Kβ/β”-Al2O3