Study of AC conductivity and dielectric relaxation in Bi${}_2$O${}_3$ modified lithium lead silicate glasses

In this research work, we have prepared lithium lead silicate glasses with varying concentrations of bismuth by following the melt-quench technique. The prepared samples are investigated by ac conductivity and electric modulus formalisms in the frequency and temperature ranges of 10${}^{-1}$-10${}^7$ Hz and 433-533 K, respectively. To check the applicability of various charge transport mechanisms in these prepared samples, the experimental data of ac conductivity was fitted with Jonscher's power law. It was found to be satisfied in the studied range of temperature and frequency. AC conductivity helps to calculate all the parameters viz.; dc conductivity, activation energy, frequency exponent parameter, and the cross over frequency. The value of ac conductivity increases with Bi${}_2$O${}_3$ concentration up to 30 mol% due to mobile lithium ions and the network modifier BiO${}_6$ unit. Thereafter, when the ratio of Bi${}_2$O${}_3$/Li${}_2$O becomes greater than unity, the conductivity values decrease due to the blocking effect of the bismuth ions in the network, forming the BiO${}_3$ pyramidal unit. In the current research, the correlated barrier hopping model is found to be suitable for explaining the ac conduction mechanism.