Nuclear-magnetic-resonance study of the electronic structure of the Ti-H system

The proton spin-lattice relaxation time $T_1$ of hydrogen in titanium hydride was measured as a function of temperature and hydrogen concentration in the temperature range where the overriding relaxation mechanism is the interaction with the conduction electrons. The hydrogen-concentration dependence and the temperature dependence of ${\left(T_{1e}T\right)}^{-\frac{1}{2}}$ is presented. A break in the temperature dependence curve of ${\left(T_{1e}T\right)}^{-\frac{1}{2}}$ was found for hydrogen concentrations having atomic ratios greater than 1.8. This is associated with a tetragonal deformation which is known to occur for the hydride. A phenomenological model of the electronic structure based on a semirigid band is proposed to explain the data. The concentration and temperature dependence of the susceptibility, hyperfine interactions, and transport properties are discussed in terms of the proposed model as well as the cause of the tetragonal deformation and the low-hydrogen-concentration limit of the hydride.