Mean-field Equation Of State Research Articles

Ferroelectric Behavior of Triglycine Fluoberillate nearTc

Dielectric-constant and hysteresis-loop measurements have been performed on single crystals of triglycine fluoberillate (TGFB) in the vicinity of the critical point to characterize the second-order transition and to compare the results with previous data on its isomorph triglycine sulfate (TGS). The mean-field critical exponents and the mean-field equation of state are shown to give a good description of the ferroelectric behavior of TGFB as expected. The parameters entering in the statistical dipolar theory of ferroelectrics are derived, in some cases independently, from the dielectric-constant and hysteresis-loop measurements, allowing a distinction between dipolar and atomic (mainly ionic) polarization. The numerical values of parameters obtained in this way for TGFB, as well as for TGS, are discussed.