N-15 AND CS-133 SOLID NMR-STUDIES ON IONIC DYNAMICS IN PLASTIC CSNO2

The temperature dependence of the N-15 and Cs-133 NMR spin-lattice rel axation times, the N-15 spin-spin relaxation time, and the N-15 and Cs -133 spectra of CsNO2 was observed in the plastic phase (209.2 < T < 6 73 K (m.p.)) and the low-temperature phase (Phase II). In Phase II we found the NO2- 180 degrees-flip, which could be attributed to the anom alous increase of the heat capacity curve, and determined the activati on energy of this motion to be 8.7-11.7 kJ mol(-1). The N-15 and Cs-13 3 spectra in this phase are inconsistent with the reported crystal str ucture R(3) over barm$ and can be explained by lower crystal symmetry. In the plastic phase we detected a new anionic motion with 11 kJ mol( -1), an isotropic NO2- reorientation with 8.5-9 kJ mol(-1), and ionic self-diffusion with 47 kJ mol(-1). The presence of ionic self-diffusio n was confirmed by measuring the electrical conductivity.