Noble Gas adsorption in quasicrystals surfaces (Al_73Ni_10Co_17)
Investigators: S. Curtarolo (Duke), W. Setyawan (Duke), R. Diehl (PSU), N. Ferralis (PSU), M. Cole (PSU).
Description.
The discovery of quasicrystalline structures in 1984 changed the
scientific community's view about crystals. The new structures were found to be
aperiodic but still preserving a long-range order and to have
symmetries forbidden by translational invariance (as 5-fold, 8-fold and 10-fold
symmetry). As a result of this discovery, the IUCr commision on
Aperiodic Crystals proposed a new definition in 1992: A crystal is any solid
with an essentially discrete diffraction diagram; the symmetry of a crystal is
implied by its diffraction image. However, the question of why do atoms form a
complex, quasiperiodic pattern rather than a regularly-repeating crystal is
still open. Besides this fundamental question, quasicrystals revealed other
unexpected properties as high resistivity, low surface friction and stickiness,
which are not yet clearly understood.
This research explores the adsorption of noble gases on quasicrystal surfaces.
19.
S. Curtarolo, W. Setyawan, R. D. Diehl, N. Ferralis, M. W. Cole,
Evolution of order in Xe films on a quasicrystal surface,
Phys. Rev. Lett. 95, 136104 (2005).
[pdf]
We report results of the first computer simulation studies of a
physically adsorbed gas on a quasicrystalline surface, Xe on
decagonal Al-Ni-Co.
The grand canonical Monte Carlo method is employed,
using a semi-empirical gas-surface interaction, based on conventional combining rules, and
the usual Lennard-Jones Xe-Xe interaction. The resulting adsorption isotherms and calculated
structures are consistent with the results of LEED experimental data.
The evolution of the bulk film begins in the second layer, while the low coverage behavior is epitaxial.
This transition from epitaxial 5-fold to bulk-like 6-fold ordering is temperature dependent,
occurring earlier (at lower coverage) for the higher temperatures.
ANIMATIONS
Animation of an adsorption isotherms at T=77K: isotherm_T77K_big.mpg. (big movie, 15MB), MPEG format.
Animation of an adsorption isotherms at T=77K: isotherm_T77K_small.mpg. (small movie, 4.5MB), MPEG format.
Animation of an experimental LEED isobar at P=1.6 10^-6 mbar isobar_experimental_LEED.mov. (6.9 MB), MOV format.
OTHER PUBLICATIONS IN THIS FIELD
23.
W. Setyawan, N. Ferralis, R. D. Diehl, M. W. Cole, and S. Curtarolo,
Xe films on a decagonal Al-Ni-Co quasicrystal surface,
in preparation (2005).
22.
R. D. Diehl, N. Ferralis, K. Pussi, M. W. Cole, W. Setyawan, and S. Curtarolo,
The ordering of a Xe monolayer on a quasicristal Al-Ni-Co surface,
in press Philosophical Magazine, (2005).
[pdf]
ext.
N. Ferralis, R. D. Diehl, K. Pussi, M. Lindroos, I. Fisher and C. J. Jenks,
Low-energy Electron Diffraction Study of Xe Adsorption on the Ten-fold Decagonal Al-Ni-Co Quasicrystal Surface,
Phys. Rev. B 69, 075410 (2004).
[pdf]
ext.
N. Ferralis, K. Pussi, M. Gierer, E. J. Cox, J. Ledieu, I. Fisher, C. J. Jenks, M. Lindroos, R. McGrath and R. D. Diehl,
Structure of the ten-fold d-Al-Ni-Co quasicrystal surface,
Phys. Rev. B 69, 153404 (2004).
[pdf]
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