RF-microwave dielectric relaxations and phase transitions in superionic protonic acid sulphates (selenates)
Abstract The complex dielectric properties of CsHSO 4 (CsHS), CsHSeO 4 (CsHSe), CsDSeO 4 (CsDSe) and NH 4 HSeO 4 (AHSe) have been studied between 100 KHz and 8 GHz. The samples are dense polycrystalline pellets sintered under pressure and annealed at various temperatures. Three and four dipolar relaxations are observed for caesium and ammonium acid selenate (sulfate) respectively and assigned to protonic species reorientations (HSO - 4 , HSeO - 4 , NH + 4 ) and to proton jump relaxation. Relaxation times, ferroelectricity, superionic conductivity and incommensurability are discussed.