Origin of dielectric relaxations in polycrystalline RbHSeO$_{4}$ above room temperature

Abstract

In the present paper, the dielectric relaxation properties of RbHSeO$_{4}$ have been studied by means of impedance spectroscopy measurements over wide ranges of frequencies at several isotherms (T$< $415 K). The frequency dependence of the permittivity data reveal a distinct dielectric relaxation at low frequency, which is about 385 Hz at 310 K, then it shifts to higher frequencies ($\sim $40 kHz) as the temperature increases. The f$_{\max}$ vs. reciprocal T shows an activated relaxation process with an activation energy of 0.9 eV, which is in close agreement with that associated with transport of charge carriers. We suggest that the observed dielectric relaxation could be attributed to polarization induced by the proton jump and selenate tetrahedral reorientations. The displacement of mobile H$^{ + }$ proton accompanied by SeO$_4^{ - 2} $ tetrahedra reorientations create structural distortion in both sublattices which induce localized dipoles like HSeO$_4^ - $.