Enhanced ionic conduction in NaNO3 by dispersed oxide inclusions

The composite solid electrolytes, NaNO3 dispersed with Al2O3, CeO2, ZrO2 and SiO2 have been prepared by melt quenching method and investigated through XRD, DSC and electrical conductivity techniques. Typical increase in conductivity is about two orders of magnitude for 10 mol% of Al2O3 at 200degreesC. The electronic transference number evaluated through do polarization method was found out to be 1 X 10(-2) at 200degreesC. The dependence of conductivity on concentration of dispersoids and particle size is in accordance with the space charge theory of conduction. The enhanced conductivity of NaNO3 homogenously doped by Ca(NO3)(2) was further enhanced by heterogeneous doping of Al2O3. By the contribution of these doping processes, the conductivity is enhanced by three orders of magnitude at 200degreesC. The experimental and theoretically calculated values of conductivity using Maier's space charge layer model are in reasonable agreement. (C) 2003 Elsevier Science Ltd. All rights reserved.