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Indexed by:期刊论文

Date of Publication:2018-05-01

Journal:SURFACE SCIENCE

Included Journals:SCIE、EI、Scopus

Volume:671

Page Number:11-16

ISSN No.:0039-6028

Key Words:Hartree-Fock simulation; Surface relaxation; Surface energy; Wulff-Gibbs construction; Hematite

Abstract:The structure and surface energy of a series of low-index surfaces of stoichiometric alpha-Fe2O3 (hematite) are investigated using the periodic HartreeFock approach with an a posteriori correction of the correlation energy. The simulations show that, amongst the modeled facets, (01 (1) over bar2) and (0001) are the most stable surfaces of hematite, which is consistent with the fact that the latter are the dominant growth faces exposed on natural alpha-Fe2O3. The Fe-terminated (0001) surface is shown to exhibit a large relaxation of the surface atoms. It is argued that this arises mainly due to the fact that the surface cations are located opposite empty cation sites in the filled-filled-unfilled cation sequence along the c-axis. In contrast, the (01 (1) over bar2) plane cuts the crystal through a plane of empty cation sites, thus giving rise to relatively small relaxations and surface energies. The small relaxations and concomitant exposure of five-coordinate cation sites may be important for the catalytic activity of hematite. The simulations also show that the relative stability of the investigated surfaces changes after a full lattice relaxation with the (0001) and (11 (2) over bar6) facets relaxing disproportionately large. Wherever possible, the simulations are compared with previous simulation data and experimental results. A Wulff-Gibbs construction is also presented. (C) 2018 Elsevier B.V. All rights reserved.