Proton Ordering and Conduction in TIH2PO4 with a Paraelectric-antiferroelectric Mixed Order

Abstract

We have studied proton ordering and proton conduction in a TIH2PO4 single crystal associated with the recently identified intermediate paraelectric-antiferroelectric mixed phase with a phase boundary temperature T-s = 327 K. According to the H-1 nuclear magnetic resonance rotating-frame spin-lattice relaxation measurements, proton ordering takes place at T-s rather than at the structural phase transition temperature T-c = 230 K. Distinct temperature dependencies of the electrical conductivity were observed below and above T-s, indicating that proton conduction in the system is dictated by the proton and the electric dipole orders.