H+-ion conductivity and ferroelectric properties of rubidium ammonium hydrogen sulphate

Electric and dielectric measurements have been used to study the superionic conductivity and the ferroelectricity respectively in Rb-0.8(NH4)(0.2)HSO4 single crystal. This material presents a high level of conductivity at hig h temperature. Activation energies were determined from the temperature dep endence of the alternating-current conductivity in the regions 440-560 K an d beyond 560 K; they are respectively 0.15 and 0.10 eV, The dielectric meas urements show an intense anomaly at 285 K indicating a ferroelectric-parael ectric phase transition. This phase transition is accompanied by a signific ant dispersion of the real part of the dielectric constant in the frequency region investigated, in accordance with the high level of conductivity of this material.