SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 92: Oxide and Insulator Surfaces II: Structure, Epitaxy and Growth

O 92.1: Vortrag

Freitag, 31. März 2023, 10:30–10:45, CHE 91

Growth of ultrathin silica films on Pt(111) and Rh(111): Influence of intermixing with the support — •Florian Kraushofer1, Matthias Krinninger1, Nils Refvik2, Friedrich Esch1, and Barbara Lechner11TU Munich, Germany — 2University of Alberta, Canada

Silica is a widely used catalyst support material for clusters and nanoparticles. Understanding the relationship between these clusters and the support is challenging, however, because SiO2 is insulating, and in most applications not crystalline, which limits the use of diffraction-based experimental techniques. Several previous studies have investigated ultrathin, quasi-2D silica films on a variety of metal supports [1], which can then be measured by scanning tunneling microscopy (STM). Previous work on Pt(111) did not result in closed films, which was attributed to lattice mismatch [2]. We show that closed films can in fact be grown on Pt(111) when silica is deposited in excess, likely due to formation of a platinum silicide layer with a slightly expanded lattice constant at the interface. We also report results of film growth on Rh(111), which is a near-perfect match to the lattice constant of freestanding SiO2 films as calculated by theory. However, no high-quality films were achieved, which we attribute to a different balance of the formation energies for silicide and oxide.

[1] C. Büchner, M. Heyde, Two-dimensional silica opens new perspectives, Prog. Surf. Sci., 92 (2017) 341-374.

[2] X. Yu, B. Yang, J. A. Boscoboinik, S. Shaikhutdinov, and H.-J. Freund, Appl. Phys. Lett. 100 (2012), 151608.

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