Erratum: Formation of a well ordered ultrathin aluminum oxide film on icosahedral AlPdMn quasicrystal [Phys. Rev. B76, 094203 (2007)]

Abstract

If the pentagonal surface of the icosahedral AlPdMn quasicrystal is exposed to oxygen, atomically thin oxide domains are formed at the surface involving predominantly Al-O bonds. The lack of Al in the alloy due to this process can adversely affect the stoichiometry and hence the structure of the quasicrystal. In fact, the shift of the concentration towards Al 50 ͑PdMn͒ 50 results in a known crystalline structure.͓3͔ In this case, the oxide layer is surprisingly similar to that observed on the ͑110͒ surface of the ordered NiAl alloy. 1 In order to avoid this formation, oxidation is performed at 700-800 K that promotes segregation of Al from the bulk to the surface and maintains the quasicrystalline stoichiometry. The elevated temperature further promotes the formation of an ordered oxide layer. Similar to the temperature effect, any improper treatment of the surface, e.g., ion bombardment during or after the oxidation process, or improper surface preparation of the quasicrystal prior to oxidation both result in oxide layers typical of those grown on crystalline surfaces.The model shown in Fig. 3 was proposed as a single domain structure in real-space for the oxide layer on the quasicrystal which was adopted from the oxide structure grown on NiAl͑110͒ ͑see, e.g., Ref. ͓22͔͒. In accordance with the global rotational symmetry of the pentagonal surface, there are five degrees of freedom for the rotational alignment of the single domain structure on the pentagonal surface. Consequently, the oxide layer is composed of five distinct twin domains each rotated by multiples of 2 / 5 with respect to the others.Here, we claim that this surface structure is based on unjustified speculations, since ͑i͒ the twin-domain structure is a consequence of the twofold symmetry of the NiAl͑110͒ surface. The pentagonal surface of i-AIPdMn, on the other hand, is fivefold symmetric. ͑ii͒ The twin-domain model delivers considerably more diffraction spots with the composite pattern than detected in LEED experiments ͑not shown͒, and ͑iii͒ was derived from the LEED pattern shown in Fig. 2c, which was obtained after a brief sputtering of the oxidized surface with Ar + ions and subsequent reoxidation. Thus, it represents a surface structure, which most likely differs significantly from the structure shown in Fig. 2b, as mentioned above. Ar + ion bombardment was found to shift the structural stability of the quasicrystalline alloy towards the cubic crystal ͓3,5͔, therefore, it is not surprising that an oxide layer forms on the sputtered surface which is almost identical to the oxide grown on the ͑110͒ surface of the NiAl alloy. The reproduction of the LEED pattern obtained from the Ar + ion-bombarded surface using the twin model is very convincing ͑the reader is referred to Figs. 1c and 1d͒ and confirms the crystalline interface structure. 1 S. Burkardt and M. Erbudak ͑unpublished͒.

CdTe and PbTe nanostructures on the oxidized pentagonal surface of an icosahedral AlPdMn quasicrystal

“…2a displays a LEED pattern of the pentagonal surface of i-AlPdMn obtained after cycles of Ar + sputtering and annealing at 700 K. The quality of the pattern indicates a well-established quasicrystalline order at the surface [16]. As previously reported [12], exposure of a well-prepared quasicrystalline surface kept at 700 K to O 2 leads to the formation of a 5 Å thick, well-ordered Al-ox film, which consists of five pairs of '-domains rotated by 72°w ith respect to each other. The corresponding LEED pattern is displayed in Fig.…”

“…Recently, we have reported the formation of a new kind of crystal-quasicrystal interface by oxidation of the pentagonal surface of the i-AlPdMn quasicrystal. A 5 Å thick, wellordered aluminum-oxide (Al-ox) film is formed, which consists of five pairs of '-domains rotated by 72°with respect to each other and of a size of about 35 ± 2 Å [12]. The alignment of one pair of '-Al-ox domains along a twofold-symmetry direction of the pentagonal surface of iAlPdMn is illustrated in Fig.…”

Oxygen-induced surface faceting of the threefold-symmetry surface of icosahedral AlPdMn quasicrystal

“…The small size of the oxide domains is determined by a large interfacial strain energy, which is usually encountered in quasicrystal-crystal interfaces [5]. Further, the oxide layers grown on icosahedral AlPdMn reconstruct in order to lower the interfacial strain energy [7], while the layers grown on decagonal AlCoNi are strongly influenced by the topology of the decagonal surface ordering [8].…”

“…Recent studies [7,8] on the oxidation behavior of the pentagonal surface of icosahedral AlPdMn and the decagonal surface of AlCoNi quasicrystals facilitate the interpretation of the oxide layers in terms of a hexagonal domain structure. The results show that, compared to single crystals, the quasicrystalline atomic ordering on the surface alters the oxide domain structure during formation such that the domains remain in the nanometer-size and locally commensurate with the quasicrystal substrate symmetry.…”

“…Recently, the selective oxidation of quasicrystals has contributed a further interesting surface phenomenon [4][5][6][7][8]. Metal oxide interfaces are of great interest for many technological applications, in particular, are ideally suited as model catalysts [9].…”