A 2ND-ORDER PHASE-TRANSITION IN NANO2 OBSERVED BY NA-23 NMR

The spin-lattice relaxation time (T1) and quadrupole splittings for Na -23 in NaNO2 have been investigated in the range of 140 - 400 K as a f unction of temperature with a pulse NMR spectrometer operating at 4.7 T. The temperature dependence of T1 was found to have an abnormal peak at 178 K. The measured quadrupole splittings as a function of tempera ture also showed a slight discontinuity at this temperature. These res ults confirm the existence of the second order phase transition at 178 K in NaNO2, previously reported by of measuring the thermal expansion and the dielectric constant.