Dielectric and Spectroscopic properties of CuO doped multi-component Li2O-PbO-B2O3-SiO2-Bi2O3-Al2O3 glass system

Multi-component silicate glasses of the chemical composition 19.4Li(2)O-20PbO-20B(2)O(3)-30SiO(2)-(10 - x) Bi2O3-0.6 CuO: x Al2O3 with x ranging from 0 to 5 mol% have been synthesized. A variety of spectroscopic (optical absorption, IR, Raman and ESR) and dielectric properties (over a range of frequency and temperature) of these glasses have been investigated as a function of Al2O3 concentration. The results of optical absorption and ESR spectral studies have indicated that a part of copper ions do exist in Cu+ state in addition to Cu2+ state especially in the samples containing low concentration of Al2O3. The IR and Raman spectral studies have revealed that there is a decreasing degree of disorder in the glass network with increase in the concentration of Al2O3 upto 3.0 mol%. The values of dielectric parameters viz., dielectric constant, loss and ac conductivity at any frequency and temperature are observed to decrease as the concentration of Al2O3 is increased up to 3.0 mol%. Such changes have been attributed to increase of redox ratio or increasing proportions of Cu+ ions that take part in the glass network with CuO4 structural units The quantitative analysis of the results of ac conductivity and dielectric properties have indicated a decrease in the insulating character of the glasses when the concentration of Al2O3 is raised beyond 3.0 mol% in the glass network. This has been attributed to adaption of aluminium ions from tetrahedral co-ordination to octahedral co-ordination and also due to declustering influence of copper ions by aluminium ions in the glass network. (C) 2013 Elsevier B.V. All rights reserved.