Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant.
Quasicrystals are long-range-ordered materials that lack translational invariance, so the study of their physical properties remains a challenging problem. Here, we have carried out inelastic-X-ray- and neutron-scattering experiments on single-grain samples of the Zn-Mg-Sc icosahedral quasicrystal and of the Zn-Sc periodic cubic 1/1 approximant, with the aim of studying the respective influence of the local order and of the long-range order (periodic or quasiperiodic) on lattice dynamics. Besides the overall similarities and the existence of a pseudo-gap in the transverse dispersion relation, marked differences are observed, the pseudo-gap being larger and better defined in the approximant than in the quasicrystal. This can be qualitatively explained using the concept of a pseudo-Brillouin-zone in the quasicrystal. These results are compared with simulations on atomic models and using oscillating pair potentials, and the simulations reproduce in detail the experimental results. This paves the way for a detailed understanding of the physics of quasicrystals.
de Boissieu
Marc
M
Sciences et Ingénierie des Matériaux et Procédés, INPGrenoble CNRS UJF, BP 75 38402 St Martin d'Hères Cedex, France. Marc.de-boissieu@ltpcm.inpg.vr
Francoual
Sonia
S
Mihalkovic
Marek
M
Shibata
Kaoru
K
Baron
Alfred Q R
AQ
Sidis
Yvan
Y
Ishimasa
Tsutomu
T
Wu
Dongmei
D
Lograsso
Thomas
T
Regnault
Louis-Pierre
LP
Gähler
Franz
F
Tsutsui
Satoshi
S
Hennion
Bernard
B
Bastie
Pierre
P
Sato
Taku J
TJ
Takakura
Hiroyuki
H
Currat
Roland
R
Tsai
An-Pang
AP