HYDROGEN IN NANOCRYSTALLINE PD - A NUCLEAR-MAGNETIC-RESONANCE STUDY

The proton spin-lattice relaxation times TI and the magnetic susceptib ility chi have been measured in nanocrystalline PdH0.037 With the aver age grain size of 19 nm in the temperature ranges 164-345 K (T-1) and 78-293 K (chi) The results are consistent with the picture of strongly inhomogeneous hydrogen distribution, most of the H atoms being locate d in grain boundary regions. In these regions the mobility of H atoms is found to be considerably higher than in coarse-grained Pd. The anom alous behavior of T1 and the amplitude of the free-induction decay bel ow 230 K is attributed to the effects of the alpha --> beta phase tran sformation. (C) 1998 Elsevier Science Ltd. All rights reserved.