The monohydrate phase exhibited a conductivity of 0.00014S/cm at 100C, and an activation energy of 57kJ/mol. When alumina particles were dispersed in the material, the conductivity was increased by almost an order of magnitude while the activation energy remained the same. It was concluded that the data were consistent with a space-charge model for the enhancement of conductivity by dispersed particles. Moreover, they did not support a model which involved the formation of higher hydrates.

O.Nakamura, J.B.Goodenough: Solid State Ionics, 1982, 7[2], 119-23