PECULIARITIES OF SPECIFIC-HEAT OF A LAYER ED FERROELECTRIC TLINS2

A Landau-type theory of homogeneous - inhomogeneous - homogeneous phas e transition in layered crystals with the coexisting ferro-antiferroel ectric order is developed. The critical exponent of specific heat is d efined: alpha = 2/3 in homogeneous phases, alpha = 0 and alpha = 1 in inhomogeneous phases near homogeneous - inhomogeneouse and inhomogeneo us - honogeneous phase transitions, respectively. The qualitative comp arison of theoretical results with experimental data for layered cryst als of TlInS2 is performed.