AC conductivity and dielectric studies of modified Li4SiO4 ceramic electrolytes

AC conductivity of modified Li4SiO4 (Li3.94Cr0.02SiO4, Li4Zr0.06Si0.94O4 and Li3.94Cr0.02Zr0.06Si0.94O4) was measured as a function of frequency in the range between 1 Hz to 1000 Hz and in temperature range between 303 K to 773 K. The frequency dependence of conductivity for these ceramic electrolytes followed the universal power law variation, σAC (ω)=σo+Aωs. The plots of pre-exponent s versus temperature of all systems suggested that the conduction mechanism in all systems can be described using correlated barrier hopping model. Meanwhile, the charge carrier concentration and mobile ion concentration in all samples was found to be constant over the temperature range of this study while mobility of ion increased with temperature implying that the increase in conductivity with temperature was due to the increase in ion mobility. The experimental results also revealed that the dielectric constant and dielectric loss decreased with frequency. The double substituted sample, Li3.94Cr0.02Zr0.06Si0.94O4 showed the highest dielectric constant and dielectric loss at low frequencies. The increase in temperature also increased the dielectric constant and dielectric loss values in all samples.