Nuclear-magnetic-resonance evidence for a new phase induced by pressure in the superionic conductorLi3N

By investigating the ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ quadrupolar NMR spectrum in a ${\mathrm{Li}}_3$N single crystal at hydrostatic pressures up to 7 kbar we have detected a new phase which is pressure induced with a transition pressure of 4.2 kbar at 300 K. The new phase is stable at normal pressure at least for several months. Two inequivalent Li sites were found with quadrupole coupling constants 406 and 164 kHz, respectively. Spine-lattice relaxation and linewidth studies indicate that the Li mobility is higher in the pressure-induced new phase than in the normal $\frac{P6\mathrm{}}{\mathrm{mmm}}$ phase.