Nuclear Magnetic Resonance Study on23Na in Sodium Nitrite in the Vicinity of the Phase Transition Temperatures

A study on 23 Na nucleus in sodium nitrite, NaNO 2 , in the vicinity of phase transition temperatures was made using nuclear magnetic resonance. Simultaneous measurements of the spectrum and the dielectric constant ε b made the one to one correspondence between them clear. The main results were as follows: A discontinuous jump of an electric field gradient tensor and thermal hysteresis were found at the transition temperature T t . The curves of quadrupole splitting versus temperature show a small kink at the transition temperature T n . Only one pair of satellite lines was observed in the sinusoidal antiferroelectric phase. The asymmetry parameter of the electric field gradient tensor, η, becomes zero at 0.3^°∼0.4^° below T t in the cooling runs.