We investigated atomically resolved interface microstructures of vacuum-deposited Pt on SnO2(hkl) (hkl = 110, 101, 111; Pt/SnO2(hkl)) substrate surfaces. The Pt/SnO2(hkl) samples were prepared by electron-beam deposition of a 1.6-nm-thick Pt layer on SnO2(hkl) at room temperature under ultrahigh vacuum (∼10−8 Pa) followed by thermal annealing. Cross-sectional structural analysis was conducted by scanning transmission electron microscopy combined with x-ray energy dispersive spectroscopy and x-ray photoelectron spectroscopy. The Pt/SnO2(101) and Pt/SnO2(111) samples clearly showed Pt(111) epitaxial growth on the SnO2(101) and (111) substrate surfaces, whereas an islandlike Pt growth was observed on SnO2(110). Increasing the annealing temperature of the samples from 473 to 673 K resulted in alloying of the deposited Pt with Sn atoms from the substrate in the case of Pt/SnO2(110). In comparison, for Pt/SnO2(101) and Pt/SnO2(111), the interfaces were atomically steep, and no Pt–Sn alloys were generated even on 673 K annealing. The results clearly showed that the morphologies of the deposited Pt and the thermal diffusion behaviors of the Pt and substrate Sn atoms, i.e., the Pt/SnO2 interface microstructure, are determined by the lattice matching of the deposited Pt and SnO2 substrate interface.

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