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First universality of conductivity spectra in superprotonic (NH4)3H(SO4)2 single crystal
Ist Teil von
Journal of physics. Condensed matter, 2019-06, Vol.31 (37), p.375401-375401
Ort / Verlag
IOP Publishing
Erscheinungsjahr
2019
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
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. The contribution, evidenced by a temperature study of frequency dependence of ″, presumably comes from polar ammonia and therefore does not reflect properties of the hopping motion of mobile ions. To get rid of it, the conductivity is calculated using the impedance data obtained from the fitting procedure of the Nyquist plots. The resulting scaled ac conductivity plot forms a single curve in a wide temperature range. Thus, (NH4)3H(SO4)2 meets criteria for the first universality, despite the fact that it undergoes the structural, superionic phase transition in the temperature range studied.