Coexistence of (011) facets with (112) facets on w(111) induced by ultrathin films of pd

Abstract

The faceting of Pd/W(111) to form nanoscale three-sided pyramids with (011) facets has been observed using a scanning tunneling microscope (STM). In contrast to the well-documented (112) faceting, which can transform the entire Pd/W(111) surface to a morphology composed completely of pyramidal (112) facets, the (011) faceting of Pd/W(111) occurs in coexistence with (112) faceting upon prolonged annealing. While (112) facets are found to grow in size (ranging from (Formula presented) to 15 nm) with increasing annealing temperatures, the dimensions of (011) facets appear to be limited to (Formula presented) The coexistence of two types of pyramidal facets is consistent with energetic considerations based on first-principles calculations. The difference in their typical sizes is, on the other hand, interpreted as an evidence for kinetic factors in the faceting processes. © 1999 The American Physical Society.