AC conductivity and mobile transport pathways in 0.45Li2O-(0-55- x)P2O5-xB2O3 glasses

Abstract

Lithium borophosphate glasses 0.45Li2O-(0.55-x)P 2O5-xB2O3 (0 ≤ x ≤ 0.40) were investigated focusing on the influence of cation mobility changes due to mixed glass former effect. Glass transition temperature (Tg) increases and molar volume decreases with B2O3 addition. Deconvolution of XPS spectra revealed that P-O-B bonds increase and non-bridging oxygens decrease with the B2O3 content. Analyses of impedance data in the conductivity formalism as a function of temperature and frequency lead to a common super master curve for ac conductivity scaling at all temperatures and all compositions indicating the relaxation mechanism is a temperature independent universal process. Molecular dynamics (MD) simulations for the same systems have been performed with an optimized potential, fitted to match bond lengths, coordination numbers and ionic conductivity (σdC). Structural effects on ion transport as the origin of the mixed glass former effect can be quantified by applying Bond valence (BV) approach to the equilibrated MD trajectories. ©The Electrochemical Society.