Theory of Possible Incommensurate Phases, Their Ferroelectricity and Their Effect on the Real Commensurate Transition in Ammonium Rochelle Salt

抄録

The new thought that has been developed for explaining the incommensurate transitions in K₂SeO₄ and NaNO₂ is applied to ammonium Rochelle salt, although there are several points of difference between ammonium Rochelle salt and the former two. As the directions of incommensurate modulation, all the x, y and z axes are taken into account. The thermodynamic potential function is logically determined. Possible ferroics are deduced, which include the real commensurate one. Some of them are found to be incommensurate and yet ferroelectric. The conditions determining which of the possible ferroics the prototypic phase should change to by a first order transition are found out.