Conductivity studies on microwave synthesized glasses using complex impedance spectroscopy

Microwave Synthesis of fast ion conducting glasses offers advantage of efficient transformation of energy and heating throughout the volume efficiently in a short time. Lithium ion transport process in a modified glass network doped with lithium salt have been studied in a wide range of compositions with a general formula xLi₂SO₄ - (100-x) [0.80 LiPO₃ : 0.20 MoO₃] where x ranges from 0 to 25 mol%. Frequency and temperature dependent conductivity measurements have been carried out in the frequency range of 10 Hz to 10 MHz and a temperature range of 313K - 353K. Conductivity in these glasses is governed by the incorporation of lithium salt in the macromolecular structure, which results in the expansion of the network structure of glass. Impedance spectra of these glasses show a single semicircle and dc conductivities are extracted from it. Activation energies (E_dc) calculated using regression analysis of Arrhenius plots decreases while conductivity (σ_dc) increases with increasing LiSO₄ mol%. Increased conductivity is due to gross structural changes initiated by the network modification and incorporation of SO₄^2-ions. The complex impedance data have been analyzed using dielectric modulus formalism to study the relaxation dynamics of the charge carriers in the investigated glasses. The observed ac conductivity spectra follow Almond-West´s single power law σ(ω) = σ(0) + Aω^s and the relaxation mechanism in these glasses are analyzed using Kohlrausch-Williams-Watts (KWW) stretched exponential function. Dynamic conductivity spectra, σ(ω) convey information about the ion dynamics occur in a time window given by the inverse angular frequency.