Phase transitions and dielectric relaxations in superionic protonic conductor HUP (H3OUO2PO4.3H2O) in the broad frequency range (10-2-1010 Hz)

Abstract
The dielectric properties of hydrogen uranyle phosphate (HUP = H3 OUO2PO4.3H2O) and its sodium homologous (NaUP = NaUO2PO4, 3 H2O) have been studied between 10-2 and 1010 Hz. The samples are dense polycrystalline pellets sintered under pressure at 25°C. Three or two dipolar relaxations are observed for HUP or NaUP respectively and assigned to protonic species reorientations (H2O, H3O+), to H3O + ions or to ions coupled water molecules jumps. Dipolar relaxation, ferroelectricity and superionic conductivity are discussed