Analysis of the Specific Heat of P-Azoxyanisole (Paa) Near the Phase Transitions

Abstract

The analysis of the experimental data for the specific heat Cp at various temperatures is given here near the nematic-isotropic liquid (TNI = 133.9 degrees C) and the solid-nematic (TSN = 117.6 degrees C) transitions in p-azoxyanisole (PAA). The analysis of the specific heat Cp is performed according to a simple power-law formula and a renormalisation-group expression. The values of the critical exponent are extracted above and below the transition temperatures of TNI and TSN for this liquid crystalline material. Our exponent values are compared with the predictions of a three-dimensional Ising model and XY model for liquid crystals. Using the specific heat Cp, the temperature dependence of the enthalpy H and the entropy S is calculated in the nematic phase (T TSN) of p-azoxyanisole.