Dynamical Diffraction and X-Ray Standing Waves from Atomic Planes Normal to a Twofold Symmetry Axis of the Quasicrystal AlPdMn

Jach, Terrence; Zhang, Yanbao; Colella, R.; Boissieu, M. de; Boudard, Michel; Goldman, A. I.; Lograsso, Thomas A.; Delaney, D.W.; Kycia, S.

doi:10.1103/physrevlett.82.2904

Cited by 46 publications

(12 citation statements)

References 25 publications

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“…Here R 0 = −iπχ h /(λ sin θ B ), q(θ) = (4π/λ) cos θ B ∆θ, f (z) = exp(−W (z)) is the static Debye-Waller factor and ϕ(z) = hu(z). According to expression (109), outside the region of the total reflection the scattering amplitude R(θ) is the Fourier transform of the complex function F (z). This function and thus the structure of the surface layer can be reconstructed directly by the use of the inverse Fourier transform.…”

Section: Phase Problemmentioning

confidence: 99%

Theory and applications of x-ray standing waves in real crystals

Vartanyants¹,

Kovalchuk

2001

Rep. Prog. Phys.

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Theoretical aspects of x-ray standing wave method for investigation of the real structure of crystals are considered in this review paper. Starting from the general approach of the secondary radiation yield from deformed crystals this theory is applied to different concreate cases. Various models of deformed crystals like: bicrystal model, multilayer model, crystals with extended deformation field are considered in detailes. Peculiarities of x-ray standing wave behavior in different scattering geometries (Bragg, Laue) are analysed in detailes. New possibilities to solve the phase problem with x-ray standing wave method are discussed in the review. General theoretical approaches are illustrated with a big number of experimental results. * present address:

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Section: Phase Problemmentioning

confidence: 99%

Theory and applications of x-ray standing waves in real crystals

Vartanyants¹,

Kovalchuk

2001

Rep. Prog. Phys.

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“…The incident beam energy was scanned using a standard Si (111) channel cut monochromator leading to an intrinsic energy resolution of about 4 10 E E − ≈ ∆ . A grazing incidence geometry was used for the X ray reflectivity measurements and X ray surface diffraction experiments.…”

Section: Methodsmentioning

confidence: 99%

“…Thanks to the possibility to produce icosahedral AlPdMn quasicrystal single grains at the cm scale with an almost perfect long range order [3][4][5][6][7] and short range order [8] this compound serves today also in surface science as a model system. 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).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2000

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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...

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“…X-ray related methods like X-ray reflectivity (XRR), 2,5-7 X-ray absorption or X-ray standing waves (XSW) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] are techniques that are suitable for a wide range of thin film and multilayer samples, and that have the potential to overcome some of the existing limitations. They do not require external standards, little or no sample preparation, and have short measuring times if they are used in combination with a synchrotron radiation source.…”

Section: Introductionmentioning

confidence: 99%