Proton conductivity and phase transition in potassium hydroxide monohydrate

The ionic conductivity of a proton conductor, namely, potassium hydroxide monohydrate, has been studied in the temperature range of 200–410 K. It has been established that the temperature dependence of the conductivity has the Arrhenius form with an activation enthalpy of ～0.4 eV. The pre-exponential factors for the intervals above and below room temperature differ by a factor of ～2.5. The anomalous temperature behavior observed in the range of 285–345 K indicates a phase transition with T _c ～ 295 K. The mechanism of proton transport has been discussed.