Electrical characterization of lithium bismuth borate glasses containing cobalt/vanadium ions

Abstract

The present work reports the frequency, temperature and composition dependence of ac & dc conductivity, dielectric constant and impedance spectroscopic parameters for glass system having composition x(2CoO·V2O5)·(30−x)Li2O·20Bi2O3·50B2O3 (x=0.0, 2.0, 5.0, 7.0 and 10.0mol%), 7CoO·23Li2O·20Bi2O3·50B2O3 and 7V2O5·23Li2O·20Bi2O3·50B2O3 synthesized through melt-quench route. The investigations are carried out overwide ranges of frequency (1kHz–5MHz) and temperature (100°C–400°C). The effects of mixed-transition metal ions (i.e. Co and/or V-ions) on ac conductivity and dielectric properties have been investigated using impedance spectroscopy. Jonscher power law (JPL) is observed to be followed by all synthesized glass compositions. A synergic change in values of all electric and dielectric parameters at 7.0mol% confirms the structural modification due to mixed transition metal ion effect in present glass system. Electric modulus of prepared glass samples exhibits an asymmetric peak for the imaginary part (M″) reflecting a non-Debye type relaxation. The complex impedance curves (Z′ (ω) vs. Z″ (ω)) for all glass samples were plotted and found to exhibit good single well-shaped semi circles over the studied temperature range which depicts a single conduction mechanism. Dc conductivity at constant applied voltage (10Volts) is also measured. Conductivity plots and electric modulus spectra were scaled according to the Summerfield Scaling Model. Both scaling behavior reflected the time temperature superposition principal and temperature independent conduction mechanism in the present glass system.