文摘
Partial substitution of P by As and of Cs by NH4, leading to the solid solution Cs1-x(NH4)xH2(PO4)y(AsO4)1-y, with x = 0.45 and y = 0.39 (abbreviated as CADPA) has been shown. Two phase transitions at T1 = 204 K and T2 = 407 K were detected and studied by dielectric measurements and impedance and modulus spectroscopy. The evolution of the dielectric constant as a function of frequency and temperature revealed that the first transition (204 K) to be first order and antiferroelectric–paraelectric. The high-temperature phase transition (407 K) leads to a superionic protonic phase, characterized by an unusual high conductivity. The conductivity relaxation parameters associated with the high-disorder protonic conduction have been determined from analysis of the M″/M″max spectrum measured in a wide temperature range. Transport properties in this material appear to be due to proton hopping mechanism.