Critical Behavior of Heat Capacity in the Vicinity of Phase Transitions in [NH[sub 2](CH[sub 3])[sub 2]][sub 5]Cd[sub 3]Cl[sub 11

Abstract

The heat capacity of a [NH2(CH3)2]5Cd3Cl11 crystal was studied calorimetrically in the temperature interval 100–300 K. The Cp(T) dependence indicates that, as the temperature is lowered, phase transitions occur at temperatures T1 = 176.5 K and T2 = 123.5 K. The thermodynamic characteristics of this crystal were determined. It is shown that the transition at T2 = 123.5 K is an incommensurate-commensurate phase transformation and that the transition at T1 = 176.5 K is a normal-incommensurate phase transition.