Abstract: | Existing evidence indicates that between 248°C and the melting point at 406°C, KOH is a rotator phase. We have shown that, as might be expected, this results in enhanced proton conductivity, and a value of 2×10−3 ohms−1 cm−1 was found at 350°C, which is the highest reported for proton conducting solid electrolytes in this temperature range. Excess protons are provided by water molecules residing on the normal OH- sites, and charge compensation is provided by CO2−3 ions in the solid solution of KOH(≈ 1 m/o K2CO3, 1.3m/o H2O). The activation energy for proton hopping between adjacent H2O and OH− species probably accounts for most of the observed activation energy of 53±3 kJ mol−1. From TGA studies the isobars at 0.05 and 10 Torr were established for KOH-rich compositions in the KOH---H2O system, and it was shown that the rotator phase of KOH is stable between these vapour pressures. |