Motional States of Protons and Dielectric Dispersion of Hexammine Nickel Chloride

Dielectric losses have been measured in hexammine nickel chloride crystals, which contain a system of protons (${\mathrm{H}}^{+}$ ions) that is responsible for a motional phase transition. The losses are well approximated by Debye curves, both above and below the transition temperature. Since this transition is not accompanied by the onset of a dipolar moment, long-range forces may be neglected, as in the similar but more complex case of hydrogen-bonded ferroelectrics, and the present results may shed light on the dynamical model of this class of substances.