Characterization of phase transition in new ferroelectric 2‐aminopyridine phosphate crystal

Abstract

The dielectric properties of 2-APP, a new ferroelectric crystal, were investigated around the ferroelectric phase transition at 103.5 K. The temperature dependence of electric permittivity was measured at dc electric fields up to 1000 kV/m. The electric permittivity was also measured in the paraelectric phase at constant temperature as a function of electric field intensity up to 150 kV/m. The results are discussed in the framework of the classical dielectric state equation and expansion coefficients A, B and C were estimated. It is found that the phase transition is of second order.

Structural Ferroelectric Phase Transition and Polymorphism in 2-Aminopyridine Dihydrogen Phosphate

“…A ferroelectric phase transition in R-2APP at 103 K was detected and characterized by electric permittivity and spontaneous polarization measurements. 3,13 Temperature dependencies of these quantities have indicated this to be a continuous second-order phase transition. We have performed variable temperature diffraction studies of this material by both single crystal and powder methods, in order to gain insight into the structural aspects of this ferroelectric transition.…”