Structures on clean (110) and (111) surfaces were studied using angle-resolved XPS, ISS and LEED. The (110) clean surface had a relaxed and reconstructed c(2 x 2) structure where the surface lanthanum atoms were displaced towards the surface and a c(2 x 2) overlayer structure was caused by displacement of the surface lanthanum atoms. The (111) clean surface had a relaxed (1 x 1) structure where the surface lanthanum atoms were displaced towards the surface. The work functions of the (100), (110) and (111) surfaces were measured from the width of UPS spectra and were ~2.3, ~2.5 and ~3.3eV, respectively. The anisotropy of the work functions was correlated with the surface structures. The origin of the unusually low work functions of the clean (100) and (110) surfaces in refractory materials was explained in terms of electric dipole moments produced by positive charges of surface lanthanum ions.

Surface Structures and Work Functions of the LaB6 (100), (110) and (111) Clean Surfaces. Nishitani, R., Aono, M., Tanaka, T., Oshima, C., Kawai, S., Iwasaki, H., Nakamura, S.: Surface Science, 1980, 93[2-3], 535-49