Nuclear Magnetic Resonance Study on ²³Na in Sodium Nitrite in the Vicinity of the Phase Transition Temperatures

Abstract

A study on ²³Na nucleus in sodium nitrite, NaNO₂, 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.