Field ion microscope observations of the reconstruction of platinum and iridium surfaces

Abstract

The thermal reconstruction of various Pt and Ir single-crystal surfaces has been studied in atomic detail with the field ion microscope. Unreconstructed surfaces, which were produced by low-temperature field evaporation, were induced to reconstruct by heating the field-ion samples under field-free conditions. As previously reported for Pt, the (110) surface of Ir was observed to reconstruct from a bulk-terminated structure to a structure consisting of missing rows of atoms. The transition took place at a temperature of 500 K, almost 200 K higher than that found for Pt. The (311), (511), and (211) planes of Pt also reconstructed to missing rows at temperatures above 400 K. Transitions from field-evaporated structures to new structures (identified as reconstructed) were also observed on Pt(100) and Ir(100) at temperatures of 270 and 470 K, respectively, but the field ion images did not exhibit sufficient resolution to identify the atomic structure of the reconstructed surfaces.