AC conductivity studies of lithium borosilicate glasses: synthesized by sol-gel process with various concentrations of nitric acid as a catalyst

摘要

Glasses of lithium borosilicate (LBS) were synthesized by sol-gel process with various concentrations (x = 0.01, 0.1, 1.0, 2.5 and 5 N) of nitric acid as a catalyst. LBS samples glass forming temperatures were monitor and optimized through XRD studies at different stages from gel to glass and to multicrystalline phases. XRD, FTIR and DSC techniques were used in the characterization of the LBS samples. Impedance measurements were made on LBS glasses, heat-treated at 698 K, synthesized with various concentrations of nitric acid at different temperatures and data were analyzed using Boukamp equivalent circuit software. The bulk conductivity was calculated from the analysis of impedance data and it is found that LBS glass synthesized with 2.5 N nitric acid concentration showed high conductivity sigma = 1.45 (+/-0.02) X 10(-7) S cm(-1) at 443 K. The activation energy (E-a) was obtained from the slopes of log(sigmaT) versus 1000/T plot in the region of 443-613 K and it is found to be 0.51 +/- 0.03 eV for high conducting (x = 2.5 N) LBS glass. The conductivity variations with LBS glasses synthesized with various concentrations of nitric acid as a catalyst is explained based on conductivity expression. AC conductivity were calculated from impedance data and analyzed using Jonscher's power law (JPL) exponent (s) for LBS glasses synthesized under various concentrations of nitric acid. The power law exponents is found to be non-linear with the concentrations of nitric acid used in the synthesis of LBS glasses. (C) 2004 Published by Elsevier B.V.