Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Phys Rev E Stat Nonlin Soft Matter Phys ; 74(3 Pt 1): 031605, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17025641

RESUMO

Quasicrystal growth remains an unsolved problem in condensed matter. The dynamics of the process is studied by means of synchrotron live imaging all along the solidification of icosahedral AlPdMn quasicrystals. The lateral motion of ledges driving faceted growth at the solid-melt interface is conclusively shown. When the solidification rate is increased, nucleation and free growth of new faceted grains occur in the melt due to the significant interface recoil induced by slow attachment kinetics. The detailed analysis of the evolution of these grains reveals the crucial role of aluminum rejection, both in the poisoning of their growth and driving fluid flow.

2.
Phys Rev Lett ; 95(25): 256105, 2005 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-16384478

RESUMO

We demonstrate that icosahedral Al-Pd-Mn quasicrystals can have nonicosahedrally ordered thermodynamic equilibrium overlayers. The formation of orthorhombic or decagonal equilibrium surface structures is determined by the phase equilibrium of the ternary alloy at given composition and temperature as well as by the surface acting as nucleation site. Nonequilibrium steady-state orthorhombic and hexagonal structures can also be derived with the same methodology when taking preferential evaporation into account. The results describe consistently all presently observed surface structures.

3.
Phys Rev Lett ; 88(25 Pt 1): 255901, 2002 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-12097101

RESUMO

We present low-temperature measurements, between 20 mK and 20 K, of the sound velocity variations in a single grain of the decagonal quasicrystal Al-Ni-Co. We have used acoustic shear waves of frequency 70 MHz propagating in the quasicrystalline planes with two different polarizations: parallel and perpendicular to the quasicrystalline planes. Our results show the presence of tunneling states (TSs) with a strong difference of the phonon-TS coupling for the two polarizations, which reveals a strong anisotropy of distribution of the orientations of the TSs in the sample. This result gives direct evidence that TSs are generated by the quasicrystalline structure itself.

5.
Phys Rev Lett ; 72(12): 1937-1940, 1994 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-10055742
6.
Phys Rev B Condens Matter ; 45(6): 3119-3121, 1992 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-10001868
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA