STUDY OF SLOW MOTION OF WATER MOLECULES IN ROCHELLE SALT AND IN AMMONIUM ROCHELLE SALT BY SPIN-LATTICE RELAXATION OF PROTONS IN ROTATING FRAME

Abstract

Abstract. - Temperature and frequency dependence of spin-lattice relaxation time in rotating frame Tlr of protons in Rochelle salt and in ammonium Rochelle salt was measured. Two groups of water molecules, called by Bjorkstam [I] A, B, C, D and a, D,y, S water molecules were studied and the correlation time zc was determined for both groups. No direct contribution of water molecules to ferroelectric dipoles was found. Measurements of Tlr of protons in 7.8 mol% ammonium Rochelle salt were performed to check our conclusions, obtained for Rochelle salt. Comparison is made with the dielectric measurements on Rochelle salt at 298 OK. Introduction. - The first known ferroelectric Rochelle salt [2] (R. S.) NaKC,H,O,. 4 H,O is still interesting since there are several open questions in the dynamics of crystal lattice, in particular at both ferro- electric transitions. R. S. is one of the few ferro- electrics with two transition temperatures and with the ferroelectric phase between the transition tempera- tures : 24 OC and