Dielectric behaviour of adsorbed water. Part 1.—Measurement at room temperature on TiO2

Abstract

The dielectric behaviour in the TiO₂–H₂O adsorption system has been investigated at frequencies from 0.1 Hz to 5 MHz at room temperature. A large dielectric dispersion has been found from 0.1 to 10⁴ Hz, which shifts to a higher frequency region when the coverage of physisorbed H₂O increases. A simultaneous increase in conductance has been observed when the coverage increases. Thus, the dielectric relaxation observed at room temperature has been interpreted in terms of the interfacial polarization, which obeys the two-layer model and increases with increasing conductance. A mechanism is postulated for an enhancement of the conductance which takes place when H₂O is adsorbed on TiO₂.