RB-87 NMR-STUDY OF THE LOW-TEMPERATURE PHASE OF RB2ZNCL4

The Rb-87 1/2 --> 1/2 NMR spectra and spin-lattice relaxation rates T-1(1) are studied in the high temperature paraelectric phase, the incommensurate phase, the ferroelectric commensurate phase, and the low temperature commensurate phase of Rb2ZnCl4 between 325 and 6 K. The changes in thc Rb-87 NMR spectra on going into the low temperature commensurate phase are compatible with the proposed crystal structure of this phase, whereas the observed T1 anomaly reflects the condensation of the soft mode inducing this transition.