AC impedance analysis of CsNO3:Al2O3 composite solid electrolyte systems

Complex impedance spectroscopic studies were carried out on CsNO3 and CsNO3–Al2O3 dispersed solid electrolyte systems (DSES) in the temperature range of 100–350 °C and the frequency 50 kHz–1 MHz. Dielectric constant, loss tangent, ac conductivity and dc ionic conductivity (obtained from CIS) in these systems are presented. DC ionic conductivity is noticed to increase with temperature in the extrinsic region in pure and dispersed systems. The enhancement of conductivity in DSES was observed to be about two orders of magnitude over its pure form in the extrinsic region. This enhancement of conductivity was attributed to the formation of space charge layer between the host material and the dispersoid. Enhancement in conductivity is found to increase with m/o up to 40 m/o where as it decreased for 80 m/o. Dielectric constant, dielectric loss and ac conductivity are also found to increase with temperature, and with mole percent it maintained the similar behavior as that of dc conductivity. These dielectric properties are interpreted in terms of space charge polarization and increased concentration of defects in the interfacial layer formed between the host and the dispersoid.