Direct-current ionic conductivity measurements were made of composites formed between the Na+ ion conductor, NaNO3, and the dispersed insulating oxide. The enhancement of the conductivity was seen to increase with the mol% of the dispersoid. The maximum enhancement observed was more than 2 orders of magnitude, with respect to the host material. Differential scanning calorimetry and X-ray diffraction studies ruled out the formation of solid solutions between the host material and the dispersoid. Experimental data, indicating a higher conductivity in dispersed systems, was interpreted in terms of the formation of a space-charge layer between the host material and the dispersoid. Within this, the defect concentration increased and was thought to provide a possible mechanism for the conductivity enhancement. The activation energies obtained from conductivity data in the extrinsic conduction region exhibited a minimum value for systems at the threshold mole percentage.

DC Ionic Conductivity of NaNO3:γ-Al2O3 Composite Solid Electrolyte System. M.V.Madhava Rao, S.Narender Reddy, A.Sadananda Chary: Physica B, 2005, 362[1-4], 193-8