.
CINaM - Centre Interdisciplinaire de Nanoscience de Marseille

Partenaires

CINaM
CNRS
Logo tutelle
UMI



Rechercher

Sur le Web du CNRS


  • CINaM
  • Campus de Luminy
  • Case 913
  • 13288 Marseille Cedex 9
  •  
  • Tel : +33(0)4 91 17 28 00
  • Fax : +33(0)4 91 41 89 16

Accueil du site > Séminaires > A venir ...

A venir ...

 
Jeudi 09 Mars 2017
Fabio Ronci
CNR - Istituto di Struttura della Materia Via del Fosso del Cavaliere, 100 00133 Roma

Jeudi 16 Mars 2017
Jean-Marie DUBOIS
Institut Jean Lamour, Nancy
Push-Pull Alloys and the Legacy of Dan Shechtman
With his famous discovery of quasicrystalline order in 1982-84, Dan Shechtman, the 2011 Nobel Laureate for Chemistry, has granted us with a fascinating field in materials science that has nowadays spread out to a variety of domains in metallurgy, geology, polymer science, artificial nanostructured materials, low temperature physics, and art. Push-pull alloys stand at the heart of the heritage and teach us a lot about the roots of order in Nature, its influence on properties, and by the way open new niches for applications. A short review of the most salient features of this domain will be given. We will begin with a simplified view at the way atomic order may be described in complex intermetallics and quasicrystals. The talk will continue with electron transport properties, which provide a signature of the breakdown of periodic order in those systems made of metals. We will then examine surface properties, with a view at the potential application niches and one, yet commercially available, application will be addressed. The talk will merely draw attention to A-B-C ternary alloys, in which the elemental constituents A, B and C are chosen in such a way that B-C interactions are repulsive, but A-B and A-C are attractive in the respective binary systems. I call such alloys “push-pull alloys” in reminiscence of push-pull amplifiers that are designed to amplify an electric signal. Push-pull alloys amplify complexity, forming complex intermetallics with tens to thousands atoms per unit cell. Few of them lead to the ultimate degree of complexity, when quasiperiodic order substitutes for crystal periodicity, which opens the way to discovering unprecedented properties such as heat insulation in Al62Cu25Fe13 (at. %). Many more compounds are known today, which share the same elemental characteristics (the picture may be extended to specific binary alloys). The results will be interpreted in terms of self-organized criticality [1]. In order to promote discussion about the essence of the quasicrystalline state (“why are the atoms where they are?”), a preliminary model will be suggested. It is based on the assumption that d-like electrons, facing the energy gaps opened at the boundaries of the Jones zone via Mizutani’s interference rule [2], impose a second wavelength to the scattering mechanism that is different from the one characteristic of the (orthogonal) s-p wave functions. Appropriate tuning of the two interference systems may cancel periodicity as predicted by the Lifshitz-Petrich model [3]. 1. P. Bak, How Nature works: the science of self-organized criticality (Copernicus Press, New York, 1996). 2. U. Mizutani et al., Chem. Soc. Rev. 41 (2012) 6799-6820. DOI: 10.1039/c2cs35161g. 3. R. Lifshitz and D.M. Petrich, Phys. Rev. Lett. 79-7 (1997) 1261-1264.

Jeudi 23 Mars 2017
Emmanuel Clouet
Service de Recherches de Métallurgie Physique, CEA Saclay, DEN, 91 191 Gif-sur-Yvette, France

Jeudi 06 Avril 2017
Patrick TABELING
Groupe Microfluidique, MEMS, Nanostructures (MMN), ESPCI, Paris

Jeudi 27 Avril 2017
Pavel JELINEK

Jeudi 18 Mai 2017
Anna KRIVOSHEEVA
Center of Nanoelectronics and Novel Materials (CNN), Belarusian State University of Informatics and Radioelectronics
State of the Art on DFT modelling and experimental synthesis of 2D dichalcogenides