Equation of State for Pressure and Temperature Induced Transitions in Uniaxial Ferroelectrics TAAP and TGSe

Abstract

Experimental investigations of phase transitions induced by temperature and by pressure in uniaxial ferroelectrics: TAAP, (telluric acid ammonium phosphate), with ordinary critical point and TGSe, (triglycine selenate), which shows a quasi-tricritical point, have been performed. The combined pressure and temperature dependences of polarization versus electric field are shown to scale well using the generalized scaling variable [1−(T/T_C + p/p_C)] which involves temperature (T) and pressure (p), being T_C the transition temperature at zero pressure and p_C, the transition pressure at zero absolute temperature.