An investigation of the YB 66(100) surface

Abstract

Scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and impact collision ion scattering spectroscopy (ICISS) studies were performed on the YB 66(100) surface. By varying the scanning conditions in STM we were able to identify two different surface structures: a regular square lattice with a lattice constant of 11.5 Å for 4 V positive sample bias and a more complex structure most likely consisting of interconnected B 12 icosahedra for a negative 2 V sample bias. A closer investigation of vacancies and dislocations in the surface square lattice imaged with 4 V positive sample bias indicates that this regular structure does not reflect the ordering of the B 156 supericosahedra. In this context, a surface structure model is offered in which the channels between the giant B 156 supericosahedra, that is, the yttrium atom sites, form the regular square lattice and decomposed B 156 units compose the irregular structure imaged with a −2 V sample bias.