Oxygen adsorption on a single-grain, quasicrystal surface

Chang, Shinn‐Liang; Chin, Wei-Ting; Zhang, C.-M.; Jenks, Cynthia J.; Thiel, Patricia A.

doi:10.1016/0039-6028(95)00564-1

Cited by 97 publications

(48 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This observation has since been confirmed in other laboratories. [15][16][17][18] Similar observations-Al depletion upon Ar ϩ sputtering-have been reported also on two other Al-rich alloys, i-Al-Cu-Fe, ͑Refs. 19 and 20͒ and decagonal Al-Ni-Co. 21 In the bulk phase diagrams, the Al-based icosahedral alloys often have a CsCl-type structure on the Al-poor side.…”

Section: Introductionsupporting

confidence: 66%

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

et al. 1998

View full text Add to dashboard Cite

Low-energy electron diffraction patterns, produced from quasicrystal surfaces by ion sputtering and annealing to temperatures below ∼700 K, can be assigned to various terminations of the cubic CsCl structure. The assignments are based upon ratios of spot spacings, estimates of surface lattice constants, bulk phase diagrams vs surface compositions, and comparisons with previous work. The CsCl overlayers are deeper than about five atomic layers, because they obscure the diffraction spots from the underlying quasicrystalline substrate. These patterns transform irreversibly to quasicrystalline(like) patterns upon annealing to higher temperatures, indicating that the cubic overlayers are metastable. Based upon the data for three chemically identical, but symmetrically inequivalent surfaces, a model is developed for the relation between the cubic overlayers and the quasicrystalline substrate. The model is based upon the related symmetries of cubic close-packed and icosahedral-packed materials. The model explains not only the symmetries of the cubic surface terminations, but also the number and orientation of domains. Keywords Ames Laboratory, Materials Science and Engineering, Physics and Astronomy Disciplines Biological and Chemical Physics | Materials Science and Engineering | Physical Chemistry CommentsThis article is from Physical Review B 58, no. 15 (1998) Low-energy electron diffraction patterns, produced from quasicrystal surfaces by ion sputtering and annealing to temperatures below ϳ700 K, can be assigned to various terminations of the cubic CsCl structure. The assignments are based upon ratios of spot spacings, estimates of surface lattice constants, bulk phase diagrams vs surface compositions, and comparisons with previous work. The CsCl overlayers are deeper than about five atomic layers, because they obscure the diffraction spots from the underlying quasicrystalline substrate. These patterns transform irreversibly to quasicrystalline͑like͒ patterns upon annealing to higher temperatures, indicating that the cubic overlayers are metastable. Based upon the data for three chemically identical, but symmetrically inequivalent surfaces, a model is developed for the relation between the cubic overlayers and the quasicrystalline substrate. The model is based upon the related symmetries of cubic close-packed and icosahedral-packed materials. The model explains not only the symmetries of the cubic surface terminations, but also the number and orientation of domains. ͓S0163-1829͑98͒00239-2͔

show abstract

Section: Introductionsupporting

confidence: 66%

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

et al. 1998

View full text Add to dashboard Cite

show abstract

“…modification [9]. Other papers describe our methods of quasicrystalline sample preparation [10], and data acquisition and reduction in LEED [10,11]. Our method of surface preparation in ultrahigh vacuum involves ion bombardment at room temperature and annealing (to temperatures in the range 870-1100 K), and is similar to that employed by Schaub et al in the STM work [6,7].…”

mentioning

confidence: 99%

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21
Gierer
¹
,
Hove
²
,
Goldman
³

et al. 1997
Phys. Rev. Lett.
Self Cite
154
10
81
0
View full text Add to dashboard Cite

“…In all cases the grain size was typically several millimeters. We studied a Bridgman grown single grain of nominal composition close to Al 72 Pd 19 9 (sample C and fractured sample, M. Boudard/M. de Boissieu).…”

Section: Methodsmentioning

confidence: 99%

“…Because of its chemical reactivity however, AlPdMn surfaces cannot be studied adequately in air where an aluminum oxide layer covers the whole sample surface [9] but requires a surface preparation under UHV (Ultra High Vacuum). Two different possible requirements on a clean surface intrinsic to the quasicrystal can be desirable: firstly a thermodynamic equilibrium between surface and the volume and secondly a simple cut of a perfect structure [10].…”

Section: Introductionmentioning

confidence: 99%

Irreversible Structural Transformation of five fold i-AlPdMn Quasicrystals after Ion Bombardment and Annealing

et al. 2000

View full text Add to dashboard Cite

Five fold i-AlPdMn surface prepared under UHV by ion bombardment and annealing was so far considered to be bulk terminated. This result was substantially based on a quantitative LEED analyses [1]. Analysis of the specular rod in a X ray diffraction experiment at grazing incidence supported this result [2]. We present a new study of this surface by high resolution X ray diffraction at normal incidence. In this Bragg configuration the diffraction peak 18 -29 for instance is at a photon energy of 2.873keV, the 72 -116 reflection at 5.725keV. This results in an analyzed thickness of the sample surface of a few micrometers.The surface was cleaned by ion bombardment. During annealing (T≅880K), we clearly observed the progressive disappearance of the initial Bragg peak characteristic of the as cast bulk sample. Conversely a new Bragg peak grows at an energy position shifted by 1eV compared to the position of the original Bragg peak. This is a clear signature for an irreversible structural transformation which takes place on at least the micron thickness. On the transformed surface, both, a LEED pattern and a RHEED pattern, characteristic for a five fold surface were easily obtained.This high resolution experiment (the relative Bragg peak shift is 3ׁ10 −4 ) was reproduced on samples from different initial compositions. This shows that five fold i-AlPdMn surface changes after preparation by ion bombardment and annealing at 900K on a micrometer thickness. This is not consistent with the conclusion that the surface is simply terminated by a cut of the original bulk. We conclude that a reorganization process of the quasicrystalline structure during annealing proceeds in the surface vicinity (probed depth is close to a few microns). Disciplines Metallurgy CommentsThis article is from MRS Proceedings 643 (2000) ABSTRACTFive fold i-AlPdMn surface prepared under UHV by ion bombardment and annealing was so far considered to be bulk terminated. This result was substantially based on a quantitative LEED analyses [1]. Analysis of the specular rod in a X ray diffraction experiment at grazing incidence supported this result [2]. We present a new study of this surface by high resolution X ray diffraction at normal incidence. In this Bragg configuration the diffraction peak 18 -29 for instance is at a photon energy of 2.873keV, the 72 -116 reflection at 5.725keV. This results in an analyzed thickness of the sample surface of a few micrometers.The surface was cleaned by ion bombardment. During annealing (T≅880K), we clearly observed the progressive disappearance of the initial Bragg peak characteristic of the as cast bulk sample. Conversely a new Bragg peak grows at an energy position shifted by 1eV compared to the position of the original Bragg peak. This is a clear signature for an irreversible structural transformation which takes place on at least the micron thickness. On the transformed surface, both, a LEED pattern and a RHEED pattern, characteristic for a five fold surface were easily obtained.This high resolution experi...

show abstract

Oxygen adsorption on a single-grain, quasicrystal surface

Cited by 97 publications

References 34 publications

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21
Gierer
¹
,
Hove
²
,
Goldman
³

et al. 1997
Phys. Rev. Lett.
Self Cite
154
10
81
0
View full text Add to dashboard Cite

Irreversible Structural Transformation of five fold i-AlPdMn Quasicrystals after Ion Bombardment and Annealing

Contact Info

Product

Resources

About

Oxygen adsorption on a single-grain, quasicrystal surface

Cited by 97 publications

References 34 publications

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

Crystalline surface structures induced by ion sputtering of Al-rich icosahedral quasicrystals

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21Gierer1, Hove2, Goldman3 et al. 1997Phys. Rev. Lett.Self Cite15410810View full textAdd to dashboardCite

Irreversible Structural Transformation of five fold i-AlPdMn Quasicrystals after Ion Bombardment and Annealing

Contact Info

Product

Resources

About

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21
Gierer
¹
,
Hove
²
,
Goldman
³

et al. 1997
Phys. Rev. Lett.
Self Cite
154
10
81
0
View full text Add to dashboard Cite