Metal-semiconductor-insulator transitions in R3Ni compounds induced by hydrogenation

Electrical resistivity and ac magnetic susceptibility measurements of R3Ni and their hydrides R3NiHx were carried out. It is shown that the conductivi ty of R3NiHx compounds with a large amount of hydrogen have semiconductor a nd insulator conductivity type as compared with metallic conduction in the original compounds R3Ni. The resistivity of the original compounds is discu ssed on the basis of a conduction electron scattering model. Strongly modif ied transport processes of the hydrides are discussed on basis of a 'hoppin g' model. (C) 2001 Elsevier Science B.V. All rights reserved.