Proton magnetic relaxation in lanthanum hydrides

The proton magnetic relaxation in LaHsub(2.08+-0.03) and LaHsub(2.98+-0.03) lanthanum hydrides was investigated by the pulse NMR method on a frequency of 16 MHz in the temperature range from -180 deg C to 400 deg C. An analysis of the temperature dependence of the times of spin-lattice Tsub(1) and spin-spin T2 proton relaxations helped establish that in the hydrides investigated the principal contribution to relaxation is due to the modulation of dipole-dipole interactions in hopping diffusion of hydrogen. An appreciable contribution to relaxation is made by interaction of protons with conduction electrons. The data obtained support the anion model of lanthanum trihydride, which, along with the proton model, explains well the transition lanthanum hydride to the semiconductor state on attaining the ratio H/La = 3