XAS-INVESTIGATION OF LOCAL DISORDER IN METALLIC NICKEL AND RANEY-NICKEL CATALYST

EXAFS measurements have been carried out at the Ni-K-edge both on a Ra ney-nickel sample and on a metallic nickel foil in the temperature ran ge from 20 to 320 Kelvin using synchrotron radiation from the storage ring ELSA in Bonn. A cumulant data analysis shows that the first-shell distance distribution in nickel foil can be considered as nearly gaus sian within the considered temperature range. In Raney-nic;el catalyst , the non-negligible value of the third cumulant suggests an asymmetri c distribution instead. The first-shell coordination number is much lo wer (N similar or equal to 6) than for metallic nickel. The MSRD is si milar to that of metallic nickel, suggesting a low degree of static di sorder.