Possible Dual-Charge-Carrier Mechanism of Surface Conduction on γ-Alumina

We cast a dual-charge-carrier model of surface conductance on γ-alumina in mathematical form. We then carry out first-principles calculations for various possible atomic-scale structures of the low- and high-temperature charge-carrier interactions with the γ-alumina surface to estimate the values of the energy parameters in the dual-charge-carrier model. By comparing the values of these energy parameters as determined by first-principles calculations to those obtained by fitting the mathematical form of the dual-charge-carrier model to experimental data, new insight is gained into the nature of the charge-carrier species. The results support the hypothesis that the intrinsic hydrogen content and surface moisture of γ-alumina provide a possible explanation of the observed thermal dependence of surface conductance.