It was noted that the (111) surface of VC0.8 formed a 1 x 1 structure after Ar ion bombardment, and annealing at temperatures of up to 1000K. Low-energy electron diffraction methods were used to study this structure, and to determine the relaxation and composition of a 4-layer slab within the surface. The slab terminated with a V layer in vacuum and was essentially stoichiometric. The interlayer spacing of the V-C double-layer which was next to the vacuum was found to be contracted by 10% with respect to the (111) spacing of the bulk. Such a marked contraction, which was not observed on the (111) surfaces of metals, was attributed to the effect of a compensating charge which gave rise to a meta-stabilization of the polar (111) surfaces of the present carbide.

J.Rundgren, Y.Gauthier, R.Baudoing-Savois, Y.Joly, L.I.Johansson: Physical Review B, 1992, 45[8], 4445-53