²⁹ Si MASNMR Spin‐Lattice Relaxation Study of α‐, β‐, and Amorphous Silicon Nitride

Abstract

The spin‐lattice relaxation times, T 1 , in α‐, β‐, and amorphous Si 3 N 4 have been obtained for the first time, using a multiple‐pulse saturation recovery method. The saturation recovery of the 29 Si magnetization follows exponential behavior under magic‐angle spinning conditions, within the limits of experimental error. A rather wide dispersion of T 1 values is observed for the phases of Si 3 N 4 : 284 ± 29 min (–46.686 ppm) and 260 ± 23 min (–48.812 ppm) for the α‐phase, 36 ± 4 min for the β‐phase, and 11 ± 1 min for the amorphous phase, assuming an exponential recovery. The values obtained for the exponent in the power‐law fitting are 0.599(9) (–46.686 ppm) and 0.61(1) (–48.812 ppm) for the α‐phase, 0.52(2) for the β‐phase, and 0.53(3) for the amorphous phase.