NMR study comparing the electronic structures of ZrHx and TiHx

The temperature and concentration dependences of the proton spin-lattice relaxation time T1, Knight shift K, and the lattice parameters were obtained for zirconium and titanium hydride samples having a wide variety of concentrations at temperatures where the relaxation rate was due primarily to interaction with the conduction electrons. A sharp peak in (T1T)-12 was found at ZrH1.80 and TiH1.92, while the tetragonal distortion occurred at lower concentrations. (T1T)-12 changed continuously across the tetragonal transition. The results are compared with recent band-structure calculations. The dominant proton hyper-fine field was attributed to core polarization and the hyperfine field was estimated to be -13.5 kG. A correlation is noted whereby the microhardness of ZrHx varies inversely with (T1T)-12.