Nuclear spin-lattice relaxation in solid cuprous halides

Measurements have been made by pulsed NMR of the spin-lattice relaxation times T 1 of 63 Cu, 65 Cu and 81 Br nuclei in three polycrystalline cuprous halides of zinc blende structure from 78 to 300 K. The temperature dependence of T 1 is well described by Van Kranendonk's temperature function and testifies to a two-phonon quadrupolar relaxation mechanism. The ratio of values of T 1 for 63 Cu and 65 Cu is in all cases in good agreement with the inverse square of their quadrupole moments. The fivefold increase in T 1 for copper nuclei on proceeding from CuCl through CuBr to CuI is attributed predominantly to its dependence on the thirteenth power of the lattice parameter. Values of gamma , the parameter characterizing antishielding and other effects, of order 10 3 are required to account for absolute values of T 1 .