High Pressure Studies of Quasicrystals
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1 High Pressure Studies of Quasicrystals
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Anne Sadoc 1,3, Jean-Paul Itié , Alain Polian and Kenneth F. Kelton 1 LPMS, Université de Cergy-Pontoise, 5 Mail Gay Lussac, Neuville sur Oise, 95031 CergyPontoise Cedex, France, [email protected]. 2 LURE, Centre Universitaire Paris-Sud, BP 34, 91898 Orsay Cedex, France 3 PMS, Université P. et M. Curie, 75252 Paris Cedex 05, France 4 Department of Physics, Washington University, St. Louis, MO 63130, USA.
ABSTRACT High pressure X-ray diffraction studies of quasicrystals are presented and discussed for icosahedral Al-Cu-Ru and Ti-Zr-Ni alloys. The results in hydrogenated Ti-Zr-Ni show that TiZr-Ni may be more compressible after hydrogenation.
INTRODUCTION High pressure X-ray diffraction studies of quasicrystals (QC) have demonstrated the high stability of quasicrystals. For example, no phase transition was detected during hydrostatic compression of icosahedral Al-Cu-Fe up to 35 GPa [1,2], Al-Cu-Ru up to 31-35 GPa [3-5], AlPd-Mn up to 40 GPa [6], Ti-Zr-Ni [7,8] or decagonal Al-Ni-Co up to 40 GPa [9]. The quasicrystal structures of icosahedral Zn-Mg-Y and Al-Pd-Mn or that of decagonal Al-Ni-Co were also found to be intrinsically stable under uniaxial high pressures up to 70 GPa [10]. Moreover, these studies have allowed the study of the evolution of the six-dimensional lattice parameter as a function of pressure and the measurement of the zero-pressure bulk modulus and its pressure derivative. However, these studies are rather difficult since drastic conditions are required to obtain reliable data. This behaviour appears specific to quasicrystals. The difficulties encountered in doing such experiments will be exemplified with the study of two quasicrystals, Al-Cu-Ru and Ti-Zr-Ni, in order to point out this unusual and intriguing behaviour of quasicrystals. Moreover, some results in hydrogenated Ti-Zr-Ni, the first experimental investigation of high pressure properties of hydrogenated QCs, will be also presented.
EXPERIMENT The icosahedral Al65Cu20Ru15 alloy was produced at the Laboratoire d'Etudes des Propriétés Electroniques des Solides (LEPES, Grenoble, France). Samples of the icosahedral phase Ti53Zr27Ni20 (Ti-Zr-Ni), and icosahedral Ti45Zr38Ni17 (Ti-Zr-Ni + 0.32 H and Ti-Zr-Ni + 1.45 H), which contain approximately 0.32 and 1.45 hydrogen atoms for each metal atom (H/M = 0.32 and 1.45), were prepared at Washington University (St. Louis, MO). Small poly-
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2 quasicrystalline flakes and also fine-grained powder of the Al-Cu-Ru alloy were investigated while small flakes of Ti-Zr-Ni ribbons and some grains of Ti-Zr-Ni + H fined-grained powder were used. The X-ray diffraction experiments were carried out at the Laboratoire pour l’Utilisation du Rayonnement Electromagnétique (LURE) using the DCI synchrotron radiation facility. The experiments, recorded on the experimental station DW11, were performed in the energy dispersive mode. The incident beam was collimated down to 50 µm x 50 µm using crossed slits. The Bragg relation between the interplanar d
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