Growth and decay of a two‐dimensional oxide quasicrystal: High‐temperature in situ microscopy

Förster, Stefan; Flege, Jan Ingo; Zollner, Eva Maria; Schumann, Florian; Hammer, René; Bayat, Alireza; Schindler, K.‐M.; Falta, J.; Widdra, W.

doi:10.1002/andp.201600250

Cited by 22 publications

(22 citation statements)

References 31 publications

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“…Under reducing conditions, a reduced oxide layer is formed starting at a threshold temperature, which fully covers the metal substrate in‐between remaining 3D bulk‐like islands. [ 25 ] Studies of Sr–Ti–O films on Pt(111) and Ba–Ti–O films on Ru(0001) report a similar phenomenon. [ 5,21 ]…”

Section: Resultsmentioning

confidence: 88%

“…For Ba–Ti–O on Pt(111), a similar ring has been observed indicating the formation of a 2D reduced oxide wetting layer, which is initially poorly ordered. [ 25,26 ] Furthermore, a long‐range ordered structure is present that gives rise to sharp superstructure spots in LEED. This superstructure is characterized by 12 intense spots at an reciprocal distance of

1.00 Å^{- 1}

around the origin of the diffraction pattern and around each of the first‐order substrate spots.…”

Section: Resultsmentioning

confidence: 99%

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

Wührl

Krahn

Schenk

et al. 2021

Physica Status Solidi (b)

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2D oxide quasicrystals (OQCs) are unique structures arising from atoms positioned at the vertices of a dodecagonal triangle–square–rhombus tiling. The prototypical example for OQCs is derived from BaTiO3 on Pt(111). Herein, scanning tunneling microscopy (STM) and low‐energy electron diffraction (LEED) investigations of 2D oxide layers derived from BaTiO3 on Pd(111) are reported. Upon ultrahigh vacuum (UHV) annealing, different long‐range ordered structures are observed with a base of four vertex atoms forming two edge‐sharing equilateral triangles. By a periodic repetition of this base in either quadratic or rectangular unit cells, a triangle–square tiling (known as σ‐phase approximant or 32.4.3.4 Archimedean tiling) or a triangle–rhombus tiling is formed. Both structures vary strongly in their vertex density. In addition, the formation of antiphase domain boundaries in the σ phase is observed resulting in a well‐ordered incorporation of rhombuses in the triangle–square tiling. A systematic variation of the frequency of these domain boundaries is identified as a mechanism for an incremental increase in the global vertex density, mediating between pure triangle–square and triangle–square–rhombus tilings.

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Section: Resultsmentioning

confidence: 88%

1.00 Å^{- 1}

around the origin of the diffraction pattern and around each of the first‐order substrate spots.…”

Section: Resultsmentioning

confidence: 99%

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

Wührl

Krahn

Schenk

et al. 2021

Physica Status Solidi (b)

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“…Note that in soft matter systems, which we want to consider here, dodecagonal quasicrystals seem to occur more often than decagonal quasicrystals [17]. Experimentally, the growth of a dodecagonal quasicrystals has recently been studied in an oxide quasicrystal, which occurs as a wetting layer of BaTiO 3 on a Pt(111)-surface [18,19].…”

Section: Introductionmentioning

confidence: 99%

Dislocation-free growth of quasicrystals from two seeds due to additional phasonic degrees of freedom

et al. 2017

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We explore the growth of two-dimensional quasicrystals, i.e., aperiodic structures that possess long-range order, from two seeds at various distances and with different orientations by using dynamical phase-field crystal calculations. We compare the results to the growth of periodic crystals from two seeds. There, a domain border consisting of dislocations is observed in case of large distances between the seed and large angles between their orientation. Furthermore, a domain border is found if the seeds are placed at a distance that does not fit to the periodic lattice. In the case of the growth of quasicrystals, we only observe domain borders for large distances and different orientations. Note that all distances do inherently not match to a perfect domain wall-free quasicrystalline structure. Nevertheless, we find dislocation-free growth for all seeds at a small enough distance and for all seeds that approximately have the same orientation. In periodic structures, the stress that occurs due to incommensurate distances between the seeds results in phononic strain fields or, in the case of too large stresses, in dislocations. In contrast, in quasicrystals an additional phasonic strain field can occur and suppress dislocations. Phasons are additional degrees of freedom that are unique to quasicrystals. As a consequence, the additional phasonic strain field helps to distribute the stress and facilitates the growth of dislocation-free quasicrystals from multiple seeds. In contrast, in the periodic case the growth from multiple seeds most likely leads to a structure with multiple domains. Our work lays the theoretical foundations for growing perfect quasicrystals from different seeds and is therefore relevant for many applications.

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“…dodecagonal oxide quasicrystal interfaces in the BaTiO 3 /Pt(111) and SrTiO 3 /Pt(111) systems. [13][14][15][16] The driving force for these unique structural modifications, resulting from thickness reduction, are far from being fully unveiled. Reduced bonding coordinations, possible strong surface polarizations, support effects and experimental conditions are supposed to play a role, but no clear picture has yet been drawn.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional oxide quasicrystal approximants with tunable electronic and magnetic properties

et al. 2021

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Growth and decay of a two‐dimensional oxide quasicrystal: High‐temperature in situ microscopy

Cited by 22 publications

References 31 publications

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

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

Dislocation-free growth of quasicrystals from two seeds due to additional phasonic degrees of freedom

Two-dimensional oxide quasicrystal approximants with tunable electronic and magnetic properties

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