Dielectric relaxation and ion transport in silver–boro-tellurite glasses

Abstract

Glass systems of composition xAg₂SO₄–20Ag₂O–(80−x) [0.50 B₂O₃–0.50 TeO₂], where x = 5, 10, 15, 20, 25 and 30 mol% have been prepared by melt-quenching technique. Frequency- and temperature-dependent conductivity measurements have been carried out in the frequency range 10 Hz to 10 MHz and at a temperature range of 303–353 K, respectively. DC conductivities exhibit Arrhenius behavior over the entire temperature range with a single activation barrier. Addition of Ag₂SO₄ expands the glass network and, consequently, conductivity increases. This suggests that the structure and network expansion are the key parameters for enhancing conductivity. Impedance spectra of these glasses show a single semicircle, indicating one type of conduction. AC conductivity behavior of the glasses was analyzed using both single power law and Kolhrauh–William–Watts (KWW) stretched exponential relaxation function. The power law exponent (s) is temperature-dependent, while the stretched exponent (β) is insensitive to temperature. Scaling behavior has also been carried out using reduced plots of conductivity with frequency, which suggests the ion transport mechanism remains unaffected by temperature and composition.

Keywords:

• ion conductivity
• boro-tellurite glass
• glass network
• silver salt
• scaling behavior
• dielectric properties
• activation energy

Acknowledgements

The authors are grateful to Professor K.J. Rao, SSCU, Indian Institute of Science, Bangalore 560012, for encouragement and useful discussions. Dr RPSC thanks Dr H.S. Maiti, Director, CGCRI and Dr Ranjan Sen, Head, GTL Laboratory, CGCRI for their support and encouragement.