Nuclear Magnetic Resonance in Vanadium Chromium Hydride

The Knight shift $K$ and the spin-lattice relaxation time $T_1$ of the nuclear magnetic resonance of ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$ are measured in the system ${\mathrm{V}}_{1-x}{\mathrm{Cr}}_x{\mathrm{H}}_y$. Values of $K_{\mathrm{V}}$ and ${\left(T_1\right)}_{\mathrm{V}}$ in the binary systems ${\mathrm{V}}_{1-x}{\mathrm{Cr}}_x$ and $\mathrm{V}{\mathrm{H}}_x$ are compared with present measurements in the ternary system using a rigid-band model. Both $K_{\mathrm{V}}$ and ${\left(T_1\right)}_{\mathrm{V}}$ depend, to a good approximation, upon the electron-per-atom ratio of the alloy, $\mathfrak{z}=5+x+y$, and are independent of relative concentrations of Cr and H. Data are consistent with the screened positive-ion model for hydrogen in the metal in which the hydrogen atom contributes its electron to the conduction band of the system. No Knight shift of the ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ spins has been detected. The temperature dependence of $T_1$ for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ was measured in several alloys. A minimum in ${\left(T_1\right)}_{\mathrm{H}}$ is attributed to thermally activated diffusion of protons. Activation energies measured range from 1.5 to 8 kcal/mole.