Phase diagram and dielectric properties of mixed Cs1-x(NH4)xH2PO4 crystals

Abstract

Influence of NH4 M Cs substitution has been studied in the mixed Cs 1 m x (NH 4 ) x H 2 PO 4 crystals system by means of dielectric measurements. The x-T phase diagram was determined: for ammonium concentrations up to 0.1 the system has a monoclinic paraelectric phase with a transition into a ferroelectric phase whose temperature increases with increasing ammonium concentration. For ammonium concentration 0.4 to 1.0 the system shows a tetragonal paraelectric phase and a transition into an antiferroelectric phase. No solid solutions with concentrations between 0.1 and 0.4 could be grown. The system was further studied with the quasi-one-dimensional Ising model and the three-dimensional anisotropic Ising model.