The effect of the cubic BaTiO3 content of a surface layer upon the ionic conductivity of Na4Zr2Si3O12 was investigated. The cubic content increased with increasing applied stress before firing, and also with increasing cooling rate during BaTiO3 processing. An enhancement of the conductivity depended upon the cubic content.

T.Takeuchi, K.Ado, Y.Saito, M.Tabuchi, C.Masquelier, O.Nakamura: Solid State Ionics, 1995, 79, 325-30