Anomalous Larmour Frequency Dependence of Proton Spin–Lattice Relaxation Time (T1) in the Ferroelectric Glycine Phosphite

We report here the results of our $^{1}H$ NMR spin lattice relaxation time $(T_1)$ studies in glycine phosphite which is ferroelectric below 224 K. The experiments have been carried out in the temperature range from 200 to 419 K and at two Larmour frequencies of 11.40 and 23.56 MHz. We have noticed a Larmour frequency dependence of $T_1$ on the high-temperature side of the $T_1$ minimum. A model is proposed based on the BPP theory to explain the observation.