Calculation of the specific heat for the first order, tricritical and second order phase transitions in NH4C1

Abstract

Abstract This work presents our calculation for the specific heat C v under an Ising model that uses our Raman frequencies of the 1/7TA (93cm 1) and 1/5TO (144cm−1) modes for NH4C1. The specific heat calculation has been performed for first-order (P = 0kbar), tricritical (P=1.6kbar) and second-order (P = 2.8kbar) phase transitions in the NH4C1 crystal. Our calculated C v values are in good agreement with the experimentally observed Cp data from the literature for NH4C1. This indicates that the NH4C1 crystal can be adequately described in the lattice region by means of the Ising model studied here.