Specific heat at a first-order phase transition: SbSI

The temperature dependence of the specific heat of SbSI at zero $E$ field and atmospheric pressure has been measured accurately from 83 to 330 K using an ac calorimetric method. It is confirmed that the first-order paraelectric-ferroelectric phase transition close to 290 K is in the neighborhood of a tricritical point. The measured curves show excellent agreement with Landau theory except for a small deviation within ± 1 K around the transition temperature. Close to $T_c$ we see an additional contribution which on the high-temperature side varies with an exponent with values from 0.8 to 1.5 for different runs.