Abstract
Specific heat measurements of CsH2 ASO4 (CDA) near the ferroelectric phase transition have been conducted, and the data show that the transition is of first order, with latent heat of 254.6 ± 1.3 J/mole. The total entropy associated with the transition is found to be 0.53R, which is equal to the values found in KH2ASO4 and KD2ASO4. The spontaneous polarization data, derived from the specific heat measurements, show a discontinuous jump at Tc of 62.5%. The results are discussed in terms of the order-disorder (SUS) and the tunneling models, indicating that tunneling is important in CDA.