DC ionic conductivity of NaNO3: γ-Al2O3 composite solid electrolyte system

We present DC ionic conductivity measurements on composites formed between Na+ ion conductor (NaNO3) and dispersed insulating oxide (alumina). Enhancement of conductivity is noticed to increase with mole percent (m/o) of the dispersoid. The maximum enhancement observed is more than two orders of magnitude with respect to the host material. X-ray diffraction and differential scanning calorimetry studies ruled out the formation of solid solutions between the host material and the dispersoid. The experimental data indicating higher conductivity in dispersed system is interpreted in terms of the formation of space charge layer between the host material and the dispersoid in which defect concentration increases and that is thought to be the possible mechanism of conductivity enhancement. Activation energies obtained from the conductivity data in the extrinsic conduction region indicated least value for the systems at threshold mole percentage.