Universalities of conductivity spectra in superprotonic conductors – pressure effect and low temperature studies

Abstract: In the last 20 years, the so called universality of conductivity spectra have been studied in disordered ion conductors, such as glasses, polymers etc. [Z. Phys. Chem. 224, 1891 (2010)]. Recently, we have shown that similar electric conductivity response can be observed in highly ordered proton conductors [Solid State Ionics 225, 268 (2012); 227, 40 (2013)]. In this presentation I would like to show the results of studies of electric properties—in particular universal features of conductivity spectra—of proton conductors that experience structural phase transition. The first part of the talk is dedicated to the studies of influence of external pressure on electric properties of (NH4)3H(SeO4)2 single crystal. The studies were performed in the temperature range 250 K < T < 330 K, that covers 4 phases: I and II – superprotonic, III and IV – ferroelastic, and in the pressure range 0.1 MPa < p < 380 MPa.

In the second part, the studies of Rb3H(SeO4)2 single crystal will be presented. Results indicate existing first and second universalities of conductivity spectra in the aforementioned crystal. The former effect exists in high temperatures, while the latter is observed at sufficiently low temperatures.