Surface study of the (100) and (010) faces of the quasicrystalapproximant Al₄(Cr, Fe)

Abstract

Complex metallic alloy / Structure / Surface / LEED / STM Abstract. Low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) results are used to study the pseudo-6-fold nature of the (100) surface of the orthorhombic quasicrystal approximant Al 4 (Cr, Fe). LEED patterns are also presented from the pseudo-10-fold (010) surface of this material. In each case the results are compared with the known bulk structure of this complex metallic alloy.

Surfaces of Al-based complex metallic alloys: atomic structure, thin film growth and reactivity

“…In parallel to the previous studies, experimental works have been performed on the (100) and (010) surfaces of the Al(Cr,Fe) crystal [37]. This orthorhombic decagonal approximant has the following unit cell parameters: a = 1.250 nm, b = 1.262 nm and c = 3.065 nm [38].…”

“…The step height is measured at 5.8 ± 0.2 Å. (b) Structural model demonstrating the inversion symmetry of adjacent terraces [37]. (Figure reproduced from [37] with permission from Oldenbourg Wissenschaftsverlag, München).…”

“…The LEED patterns exhibit the surface unit mesh along with the expected pseudo-tenfold symmetry. However, none of the preparations used has led to a terrace-step surface morphology suitable for STM analysis [37]. …”

Real space crystallography of a complex metallic alloy: high-angle annular dark-field scanning transmission electron microscopy of o-Al4(Cr,Fe)

“…The enhanced corrosion resistance of this phase is ascribed to the passivating effect given by Cr. The reactivity of this intermetallic has been the subject of a detailed study under ultra high vacuum (UHV) as well as in ambient conditions, and the material has been found to exhibit an ordered oxide growth during the first stage of oxidation in UHV and an anisotropic behavior of the oxidation and of the corrosion properties relative to the three low-index [100], [010] and [001] surface terminations (Parle et al, 2013;Smerdon et al, 2009). Nevertheless, the absence of an accurate bulk structural model with all the split occupancies resolved is hindering the development of a representation for the surface structure and a detailed mechanism of its oxidation/corrosion.…”

Ordering and growth of Xe films on the 10-fold quasicrystalline approximant Al13Co4(100) surface

“…However, their long-range order is periodic rather than aperiodic, and this periodicity greatly facilitates their structure determination. Since samples have only recently become available in large enough sizes for most surface techniques [17][18][19][20][21] , there are very few studies of growth on these surfaces 22 . In this study, we have performed adsorption studies of Xe on the pseudo-10-f surface of orthorhombic Al 13 Co 4 (100) 23 , which is an approximant of the 10-fold surface of the decagonal Al-Co-Ni quasicrystal, which was studied earlier 9-11, 24, 25 .…”