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 Lechner¹ — ¹TU 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.