Order-Disorder Phase Transition and Dielectric Constant of Ice Ic

A theoretical study is made of the order-disorder transition of cubic ice Ic, where interaction energies between water molecules are considered, seven order parameters are used, and Takagi's method is employed. The ordered phase is ferroelectric when the interaction energies between neighbouring molecules are assumed to be the same as that in ice Ih. The transition is of the first order. The Curie-Weiss temperature θ C is the same as that of Ih in the c -axis and the transition temperature is 1.29θ C =59 K. The phase transition from ice Ic to Ih is discussed.