Abstract
(1) D. C. conductivity of Mg(PO3)2 glasses at room temperature was drastically enhanced from -1015S·cm-1 to -5×10-4S·cm-1 and the activation energy of the conduction was greatly reduced from 1.1eV to 0.18eV upon implantation of 120keV H+ to a fluence of 1×1018cm-2. Almost the same changes in conductivities and the activation energy were obtained for the glasses implanted with 100keV D+ (the calculated depth, -1μm, corresponds to that of 120keV H+) to the same fluence. No high proton conduction (>10-8S·cm-1 at room temperature) was observed for SiO2 glasses implanted with 120keV H+ to a fluence of 1×1018cm-2.
(2) The observed conductivity in the H+ (1×1018cm-2)-implanted Mg(PO3)2 glasses was higher by 8 orders of magnitude than the conductivity calculated using an empirical relation which was obtained for various oxides glasses containing residual X-OH groups (H2O-free). The activation energy (-0.2eV) of the conduction was close to that in fast proton conducting crystals of hydrated heteropolyacids containing POH and H2O such as H3Mo12PO4⋅29H2O. These results indicate that coexistence of acidic X-OH such as P-OH and molecular water is a structural requirement for the emergence of fast proton conduction in oxide glasses.
