Nuclear Magnetic Relaxation ofF19in Rare-Earth-Doped LaF3

Nuclear relaxation times $T_1$ and $T_2$ have been measured for ${\mathrm{F}}^{19}$ nuclei in powdered La${\mathrm{F}}_3$ samples containing ${\mathrm{Pr}}^{3+}$ and ${\mathrm{Nd}}^{3+}$ ions. Resonance frequencies of 15.9 and 30.0 MHz were employed and sample temperatures were between 150 and 800°K. Nominal ion concentrations ranged from 0.1 to 10 at.%. The $T_2$ data confirm the two-sublattice model proposed by Goldman and Shen. The $T_1$ data indicate that spin-lattice relaxation arises from both spin diffusion and atomic diffusion to the impurity sites.