IMPEDANCE AND H-2-NMR STUDIES OF STOICHIOMETRIC ALKALINE HYDROXIDE HYDRATES

Hydrates of the alkaline hydroxides LiOH, NaOH, KOH and CsOH in their liquid and solid states were investigated using impedance spectroscopy. KOH . 4H2O was studied using deuteron NMR. From the impedance measurements the electrical conductivity of the hydrate was evaluated. It is an important result of these measurements that the lithium and sodium hydroxide hydrates exhibit a poor conductivity in the solid state; the activation energies of conductivity exceed 3 eV. The potassium and cesium hydroxide hydrates, however, are considerably more conductive in the solid state, especially at low temperatures with activation energies around 0.7 eV. Linewidths and T1 and T2 relaxation times were determined as a function of temperature in the liquid and solid hydrate. The NMR measurements indicate that the protons (deuterons) are the mobile species. The differences in conductivity may be due to a size effect of the cation in that large cations with a single charge favor an extended water network which maybe of clathrate-like structure.