The Role of Lorentz Factors in Rochelle Salt

Mitsui's local field model of phase transitions in Rochelle salt is reexamined. The region for β and β', Lorentz factors, which yield spontaneous polarization only in intermediate temperatures, is extended. The cases that Mitsui treated where β and β' are both positive are included as a part of the present result. It has turned out that the sum of β and β' must be positive in order that a ferroelectric phase should appear either at low temperature side or at some intermediate temperatures.