NMR Studies of 7Li in Polycrystalline Lithium Nitride

The ⁷Li NMR spectrum for polycrystalline lithium nitride has been examined as a function of both temperature and magnetic field. Two central m=½ to m=—½ transitions and two pairs of $\mathrm{m=\pm }\frac{3}{2}$ to m=±½ satellite transitions have been observed; these results are consistent with the presence of the two nonequivalent lithium sites in the known crystal structure of Li₃N. The quadrupole coupling constants for the two lithium sites, as determined from the frequency separation of the satellite transitions, are 288±4 and 584±6 kc/sec at room temperature. These values are in good agreement with those determined from the field dependence of the second‐order quadrupolar widths of the two m=½ to m=—½ transitions. The central transitions have been examined as a function of temperature at a resonant frequency of 16 Mc/sec, where the linewidth is determined primarily by dipolar effects. As the temperature is increased from 77°K, the linewidths remain relatively constant at low temperatures but narrow abruptly between roughly −75°C and room temperature. The observed narrowing is attributed to the diffusion of lithium ions.