Evidence for H (D) ordering in PdH/sub x/ (PdD/sub x/)

Resistivity, annealing, and neutron-diffraction studies of PdH/sub x/ and PdD/sub x/ provide evidence for ordering of the H and D atoms on the octahedral interstitial sublattice. Neutron diffraction results on a PdD/sub 0.76/ single crystal indicate that the D atoms order on the fcc interstitial lattice with every fifth (4,2,0) plane vacant and all others filled, corresponding to the Ni/sub 4/Mo structure.