Proton dynamics in superprotonic RbH(SeO)crystal by broadband dielectric spectroscopy.

Broadband dielectric and AC conductivity spectra (1 Hz to 1 THz) of the superprotonic single crystal RbH(SeO)(RHSe) along theaxis were studied in a wide temperature range 10 K << 475 K that covers the ferroelastic (< 453 K) and superprotonic (> 453 K) phases. A contribution of the interfacial electrode polarization layers was separated from the bulk electrical properties and the bulk DC conductivity was evaluated above room temperature. The phase transition to the superprotonic phase was shown to be connected with the steep but almost continuous increase in bulk DC conductivity, and with giant permittivity effects due to the enhanced bulk proton hopping and interfacial electrode polarization layers.

First universality of conductivity spectra in superprotonic (NH)H(SO) single crystal.

We present the frequency study of electric conductivity in the superprotonic single crystal in a wide temperature range covering the superprotonic phase I and the low conducting, ferroelastic phase II. The data below microwave frequencies are analyzed using the Summerfield scaling method to check for presence of the first universality. The scaled conductivity obtained from the raw experimental data plotted versus scaled frequency do not show the universality because it contains, in a low temperature range, steps related to relaxational dielectric contribution.

Uncommon first universality of conductivity in superprotonic (NH)H(SeO) single crystals.

The proton conducting crystal (NH4)3H(SeO4)2 is examined to check whether the first universality of conductivity spectra is sensitive to subtle changes in the crystal structure and proton dynamics caused by external pressure. The ac conductivity was measured along the trigonal c axis by means of impedance spectroscopy, in the frequency range from 100 Hz to 1 MHz, at temperatures 250 K < T < 330 K and pressures 0.1 < p < 380 MPa.