Origin of the Temperature Dependence of Proton Conductivity in Phosphate Glass Prepared by Alkali-Proton Substitution Technique

The temperature dependence of proton conductivity in 36HO 1/2 −4NbO 5/2 −2BaO-4LaO 3/2 −4GeO 2 −1BO 3/2 −49PO 5/2 glasses prepared through the alkali-proton substitution method was investigated in this study. The activation energy of proton conduction, E a , was found to exhibit an non-Arrhenius type temperature dependence. The origin of the temperature dependence of the proton conductivity caused by thermal expansion of the glass structure was discussed in terms of the effect of changes in the local environment surrounding the protons. These changes were elucidated using Raman spectroscopy, 1 H- and 31 P-NMR, infrared spectroscopy, and molecular modeling. Because protons form O-H bonds, they are sensitive to changes in the distance between two oxygen atoms, which affects the strength of the hydrogen bond, and concluded that there is a temperature dependence as observed.