Structure analysis of the TiC(001) surface with transition metal impurities (Zr, Nb, Mo)

The surface structures of TiC(001) crystals with dilute transition metal impurities heated up to around 2000 K (0.6 wt.% of Zr, Nb and Mo) have been investigated by an Li+ impact collision ion scattering spectroscopy combined with a three dimensional three-atom computer simulation. The TiC(001) surface shows the 1×1 structure before and after segregation of the impurities and the impurity atom of these metals substitutes for the Ti atom at the topmost surface layer. The group VIa impurity, such as Mo, is segregated at the TiC(001) surface with carbon vacancies in their nearest neighbors, but the group IVa and Va metal (Zr and Nb) impurities are segregated without the carbon vacancies. The segregated impurity atoms are located at levels shifted somewhat from the TiC(001) surface.