Multipulse NMR investigation of band structure in titanium hydride: proton Knight shift and spin-lattice relaxation

The proton spin-lattice relaxation time T₁ and Knight shift K in TiH_x (0.44<or=x<or=2.00) were measured as a function of temperature and hydrogen concentration using several kinds of multipulse NMR technique. For interpretation of the experimental data, the customary scheme of electronic band structure for transition metals in the tight-binding approximation was assumed. The main contribution to K and (T_1eT)^-1/2 was found to be given by the interaction of protons with the titanium 3d spins; these two quantities are thus proportional to the 3d electron density of states at the Fermi level N_d(E_F). N_d(E_F) depends strongly upon hydrogen concentration and decreases with increasing tetragonal distortion for x>or=1.77. It was found that the character of the 3d states at E_F changes with both hydrogen concentration and tetragonal distortion. N_d(E_F) data were determined for some values of x both in the FCC and in the FCT phases.