Hydrogen in nanocrystalline Pd: a nuclear magnetic resonance study

Abstract The proton spin–lattice relaxation times T 1 and the magnetic susceptibility χ have been measured in nanocrystalline PdH 0.037 with the average grain size of 19 nm in the temperature ranges 164–345 K ( T 1 ) and 78–293 K (χ). The results are consistent with the picture of strongly inhomogeneous hydrogen distribution, most of the H atoms being located in grain boundary regions. In these regions the mobility of H atoms is found to be considerably higher than in coarse-grained Pd. The anomalous behavior of T 1 and the amplitude of the free-induction decay below 230 K is attributed to the effects of the α → β phase transformation.