Quasicrystals and their Approximants in 2D Ternary Oxides

Abstract

2D oxide quasicrystals (OQCs) are recently discovered aperiodic, but well‐ordered oxide interfaces. In this topical review, an introduction to these new thin‐film systems is given. The concept of quasicrystals and their approximants is explained for and derived OQCs and related periodic structures in these 2D oxides. In situ microscopy unravels the high‐temperature formation process of OQCs on Pt(111). The dodecagonal structure is discussed regarding tiling statistics and tiling decoration based on the results of atomically resolved scanning tunneling microscopy and various diffraction techniques. In addition, angle‐resolved ultraviolet photoemission spectroscopy and X‐ray photoelectron spectroscopy results prove a metallic character of the 2D oxide.

Two-dimensional square and hexagonal oxide quasicrystal approximants in SrTiO3 films grown on Pt(111)/Al2O3(0001)

“…Simulated STM images based on density functional theory (DFT) calculations are found in excellent agreement with the experimental data. Contrary to the literature, 16 the results indicate that the STM contrast mainly originates from Sr atoms slightly protruding above the mean surface plane. Total energy calculations show that the adhesion of the oxide layers is similar for the square and hexagonal complex structures, attributed in both cases to electronic interactions – charge transfer and hybridization – between the adlayer and the substrate.…”

Two-dimensional binary metal-oxide quasicrystal approximants

“…Similar systems based on Sr were also reported [19]. Interestingly, those Ba-derived systems were found to exhibit a metallic character [20] (for a topical review see [21]).…”

Antiphase Domain Boundary Formation in 2D Ba–Ti–O on Pd(111): An Alternative to Phase Separation

“…The observed behavior is typical for ultrathin ternary oxide films on metal support and has been characterized in 2D Ba–Ti–O films on Pt(111) before, see ref. [24]. The fully oxidized ternary oxide tends to form 3D perovskite islands upon annealing and, therefore, to dewet the metal surface between the islands.…”