Structural study of the five-fold surface of the Al70Pd21Mn9 quasicrystal

Ledieu, J.; Munz, A.W.; Parker, Timothy M.; McGrath, R.; Diehl, Renee D.; Delaney, D.W.; Lograsso, Thomas A.

doi:10.1016/s0039-6028(99)00144-2

Cited by 51 publications

(50 citation statements)

References 14 publications

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“…On atomically resolved STM images some typical local configurations of atoms can be recognised [6,7,8]. It has been shown [2,6], that the experimentally observed features are consistent with a bulk terminated structure [9]. Several typical local arrangements of atoms were found by various groups.…”

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confidence: 90%

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Local configurations on surfaces of icosahedral quasicrystals

Kasner¹,

Papadopolos²

2006

Philosophical Magazine

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confidence: 90%

“…Clean and atomically flat surfaces [1,2,3] of icosahedral quasicrystals, in particular the stable fivefold surfaces of icosahedral Al-Pd-Mn (i-AlPdMn), exhibiting flat terraces [1,4,5], have been investigated in the last years. On atomically resolved STM images some typical local configurations of atoms can be recognised [6,7,8].…”

mentioning

confidence: 99%

Local configurations on surfaces of icosahedral quasicrystals

Kasner¹,

Papadopolos²

2006

Philosophical Magazine

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“…The clean surface was prepared using a cumulative anneal time of 19 h, as has previously been found to be required to produce a well-ordered flat surface. 20 Surface ordering and cleanliness were monitored using LEED and Auger electron spectroscopy in the preparation chamber. Bi deposition was carried out using a miniature K cell at 590°C.…”

Section: Methodsmentioning

confidence: 99%

“…At higher coverages ͑above 0.5 ML͒ it was proposed that the additional Bi atoms fill the area between the pentagons but the precise positions could not be established since atomic resolution was lost in the STM images. 13 At the monolayer deposition level, a study using lowenergy electron diffraction ͑LEED͒ and helium atom diffraction ͑HAS͒ of both Bi and Sb on the fivefold surface of i-Al 71 Pd 20 Mn 9 and on the tenfold surface of d-Al 72 Ni 11 Co 17 , indicated the formation of pseudomorphic films at 300°C.…”

Section: Introductionmentioning

confidence: 99%

Two- and three-dimensional growth of Bi oni-Al-Pd-Mn studied using medium-energy ion scattering

et al. 2010

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Recent work on the growth of thin metal films on quasicrystalline substrates has indicated the formation of so-called "magic height" islands with multiples of 4 atomic layers ͑AL͒ arising as a result of quantum size effects, which lead to enhanced stability. Here the results of a study are reported of Bi deposition on i-Al-Pd-Mn using medium-energy ion scattering to characterize the island thickness and the structural arrangement of Bi atoms within the islands. In addition, data were taken from annealed surfaces after Bi cluster desorption to leave a single aperiodic monolayer of Bi at the surface. Scattered-ion energy spectra from the Bi islands are consistent with a single Bi monolayer covered with mainly 4 AL islands for both 1.8 and 3.2 monolayer equivalent coverages but with some occupation of 2 and 8 Al islands as well. The angular dependence of the scattered-ion intensity ͑"blocking curve"͒ from Bi has been compared with simulations for various models of both rhombohedral Bi and a distorted "black-phosphorus"-like structure. The data demonstrate bilayer formation within the Bi islands. In the case of the aperiodic Bi monolayer, the blocking curves from substrate scattering are found to be inconsistent with two high-symmetry sites on the quasicrystalline surface that theory indicates are energetically favorable but do not exclude the formation of pentagonal arrangements of Bi atoms as seen in other recent experimental work.

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“…In addition, large changes in surface composition were found. These effects exist on surfaces prepared by sputter and annealing cycles [15][16][17][18][19] as well as by cleavage and subsequent annealing. [20][21][22] To date the physical origins of these effects have been attributed to preferential sputtering, preferential evaporation under Langmuir conditions, chemical inhomogeneities, and segregation.…”

Section: Introductionmentioning

confidence: 99%

Surface structure of Al-Pd-Mn quasicrystals: Existence of supersaturated bulk vacancy concentrations

et al. 2003

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We identified the presence and chemical nature of bulk vacancies in Al-Pd-Mn quasicrystals by measuring the structure and composition of two-and fivefold cleavage surfaces of different preannealed quasicrystals subjected to postcleavage heat treatments using scanning electron microscopy and Auger electron spectroscopy. A strong dependence of the surface structure from the preannealing is observed and explained by varying concentrations of bulk vacancies. The analysis of the data shows that as-grown Al-Pd-Mn quasicrystals contain Al, Pd, and Mn vacancies in supersaturated but near stoichiometric concentrations, while long-term preannealed samples contain a much lower vacancy concentration, with a tendency to have excess Al vacancies. We found that Al and Mn vacancies are more mobile at lower temperatures than Pd vacancies, and that the diffusion of Mn vacancies is directly coupled to the mobility of Al vacancies. The results demonstrate that the evolution of the surface structure is primarily affected by bulk vacancies migrating toward the surface during heat treatments and provide a new methodology to characterize the vacancies in intermetallic alloys. We identified the presence and chemical nature of bulk vacancies in Al-Pd-Mn quasicrystals by measuring the structure and composition of two-and fivefold cleavage surfaces of different preannealed quasicrystals subjected to postcleavage heat treatments using scanning electron microscopy and Auger electron spectroscopy. A strong dependence of the surface structure from the preannealing is observed and explained by varying concentrations of bulk vacancies. The analysis of the data shows that as-grown Al-Pd-Mn quasicrystals contain Al, Pd, and Mn vacancies in supersaturated but near stoichiometric concentrations, while long-term preannealed samples contain a much lower vacancy concentration, with a tendency to have excess Al vacancies. We found that Al and Mn vacancies are more mobile at lower temperatures than Pd vacancies, and that the diffusion of Mn vacancies is directly coupled to the mobility of Al vacancies. The results demonstrate that the evolution of the surface structure is primarily affected by bulk vacancies migrating toward the surface during heat treatments and provide a new methodology to characterize the vacancies in intermetallic alloys. Keywords Ames Laboratory Disciplines Physical Chemistry Comments This article is from

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Structural study of the five-fold surface of the Al70Pd21Mn9 quasicrystal

Cited by 51 publications

References 14 publications

Local configurations on surfaces of icosahedral quasicrystals

Local configurations on surfaces of icosahedral quasicrystals

Two- and three-dimensional growth of Bi oni-Al-Pd-Mn studied using medium-energy ion scattering

Surface structure of Al-Pd-Mn quasicrystals: Existence of supersaturated bulk vacancy concentrations

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