Stoichiometric reconstruction of the Al<sub>2</sub>O<sub>3</sub>(0001) surface.
basic_science · Level V
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- Record sourced from PubMed, PMID 39265005.
- Also identified by DOI 10.1126/science.adq4744.
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Abstract
Macroscopic properties of materials stem from fundamental atomic-scale details, yet for insulators, resolving surface structures remains a challenge. We imaged the basal (0001) plane of α-aluminum oxide (α-Al<sub>2</sub>O<sub>3</sub>) using noncontact atomic force microscopy with an atomically defined tip apex. The surface formed a complex ([Formula: see text] × [Formula: see text])<i>R</i>±9° reconstruction. The lateral positions of the individual oxygen and aluminum surface atoms come directly from experiment; we determined with computational modeling how these connect to the underlying crystal bulk. Before the restructuring, the surface Al atoms assume an unfavorable, threefold planar coordination; the reconstruction allows a rehybridization with subsurface O that leads to a substantial energy gain. The reconstructed surface remains stoichiometric, Al<sub>2</sub>O<sub>3</sub>.