Influence of germanium oxide addition on the electrical properties of Li2O-B2O3-P2O5 glasses

Lithium ion transport upon the addition of germanium oxide in a series of mixed glass former lithium borophosphate glasses has been investigated. The electrical and dielectric properties of (100 - x)[0.5Li(2)O-0.1B(2)O(3)-0.4P(2)O(5)]-xGeO(2) with 0-25 mol% GeO2 glasses have been studied over a wide temperature (183-523 K) and frequency range (0.01 Hz-1 MHz). The increase in dc conductivity with the addition of GeO2 is attributed to the formation of ion conducting channels arising from the structural modification and formation of the P-O-Ge linkages, resulting in an easy migration of Li+ ions along these bonds. At higher GeO2 content glass network becomes more densely packed and ionic conductivity is slightly hindered as a consequence of the increase of bonding forces inside the network. Such a decrease in the conductivity is more reflection of the stronger cross-linkage in the glass network than that of the slight decrease in the Li+ ion concentration. The electrical modulus formalism is used to describe the dielectric relaxation. The scaling of the ac conductivity results in an excellent collapse onto common master curve whereas the electrical modulus spectra showed slight deviation indicating the distribution of relaxation times caused by the presence of various structural units in the glass network. (C) 2013 Elsevier B.V. All rights reserved.