THE SPECIFIC-HEAT OF THE FERROELECTRIC PHASE-TRANSITION IN N(CH3)4CDBR3

The specific heat of N(CH3)4CdBr3 from 50 to 300 K has been measured b y adiabatic calorimetry, using both static and dynamic methods. The ob tained results have permitted a careful study of the ferro-paraelectri c phase transition the crystal shows at 160 K. The available spectrosc opic data have been used to generate a reliable baseline which account s for the normal lattice contribution to the specific heat. These resu lts allow for an accurate estimation of the phase transition thermodyn amic functions: DELTAH = 2620 J.mol-1 and DELTAS = 18.04 J.(mol-degree s-C)-1. These high values are in agreement with the predictions of the 6 well potential Frenkel model.