LAUSR

Abstract Effect of adding WO 3 into Li 2 O–Sb 2 O 3 –PbO–GeO 2 glasses on dielectric properties viz. , dielectric constant, e′(ω), loss, tan δ, ac conductivity, σ ac , and electric moduli, M(ω), over a wide range of frequency viz., 0.01 Hz to 1 MHz and in temperature range from 303 to 523 K have been studied. Ac and dc conductivities as well as dielectric parameters exhibited the lowest values at 3.0 mol% of WO 3 . Quantum mechanical tunneling (QMT) is used for the analysis of ac conductivity. The variations of dc conductivity, analyzed by small polaron hoping model, are explained in terms of variations in the redox ratio of tungsten ions. Relaxation dynamics was investigated using electrical modulus formalism and such effects are attributed to the formation of W 5+ O 3- complexes. The structural modifications in the glass network have been quantitatively analyzed by IR, optical absorption and EPR spectroscopic studies.