The role of chromium ions on dielectric and spectroscopic properties of Li2O-PbO-B2O3-P2O5 glasses

Li2O-PbO-B2O3-P2O5 glasses containing different concentrations of Cr2O3 ranging from 0 to 1 mol% were synthesized by melt quenching technique. The amorphous nature of the glasses was asserted by X-ray diffractometry. The dielectric properties i.e., dielectric constant (epsilon'), loss factor (tan delta) and a.c. conductivity (sigma(ac)) over a range of frequency 10(3)-10(6) Hz in the temperature range 303-573 K have been carried out on these samples. The results have been analyzed in the light of different oxidation states of chromium ions with the help of data on infrared, optical absorption and ESR spectra. The analysis of the results indicates that when the concentration of Cr2O3 is increased in the glass matrix the Cr3+ ions which act as modifiers with CrO6 structural units increase. The Cr6+ ions which enter the network as glass formers with CrO42- structural units decrease with increase in dopant concentration. (C) 2014 Elsevier B.V. All rights reserved.