Hide/Show Apps

Specific heat of NH4Br and NH4BrxCl1-x crystals close to the antiferroelectric transition

We calculate the specific heat C-VI of NH4Br and mixed crystals of NH4BrxCl1-x using the Ising model for the transition between the disordered (D) and antiferro- (AF) electric phases in these crystalline systems. Our C-VI values, which we calculated for x(Br)=1, 0.26, and 0.51 are in good agreement, both below and above T-C, with the observed C-P data from the literature. Our value of congruent to 0.1 (T < T-C and T>T-C) for the critical exponent of the specific heat agrees with the value of 0.125 predicted by a three-dimensional Ising model.