Effect of nanocrystalline alumina on ionic conductivity of rubidium nitrate solid electrolyte system

Complex impedance spectroscopic studies were carried out on RbNO3 single crystal and polycrystalline samples in the temperature range between 50 and 300 °C. The ionic conductivity in polycrystalline sample is higher, about one order of magnitude, than that of single crystals. The increase in the value of conductivity in pellets could be due to increase in the concentration of defects at the grain boundaries, which can arise normally due to surface space charge and surface conduction of the sample. RbNO3-Al2O3 composite solid electrolyte system has been characterized by DSC. Maximum enhancement of conductivity observed was more than two orders of magnitude at 140 °C in the RbNO3-40 m/o Al2O3 system as against that in pure system. The enhanced conductivity in dispersed solid electrolyte system (DSES) was attributed to the formation of a space charge layer between the host material and the dispersoid.