Segregation of Carbon to the (100) Surface of Nickel

Abstract

The reversible segregation of carbon to the (100) surface of nickel has been observed. The surface was studied at temperature through measurements of work function changes and observations of LEED patterns and Auger spectra. The work function increases with temperature by about 0.63 eV in the temperature range 500°–800°K. This difference is close to that obtained from reported values of the work function for Ni (100) and for carbon. Below about 650°K the diffraction pattern contains rings characteristic of a graphite layer with its basal plane parallel to the substrate. In contrast with previous LEED observations of graphite precipitation at single‐crystal surfaces, the segregation described here is reversible under temperature cycling.