Epitaxy as a route to understanding quasicrystallinity

Lead Research Organisation: University of Liverpool
Department Name: Physics

Abstract

One of the emerging research fields in solid-state physics is quasicrystal. Quasicrystals are alloys of specific stoichiometry, which differ from other two known states, crystal and amorphous. They possess aperiodic long range order often associated with crystallographically forbidden rotational symmetries and exhibit many outstanding physical properties. However, the important question are these properties solely related to quasicrystallinity? remains unresolved.This Fellowship proposal aims to resolve this intriguing question by a method of surface science. The surface of quasicrystals will be used as a template to grow pseudomorphic films of a single element. Such films will have quasiperiodic structure but with a reduced chemical complexity compared to the bulk quasicrystals. Thus, these films could potentially be used to study the influence of quasicrystallinity on the associated physical properties, independently of the complex alloy-composition.A promising application of quasicrystals is in catalysis. Because of the complex nature of real world catalysts, it has not been possible to achieve systematic information on the parameters influencing the activity. This proposal plans to study simple and well-defined model catalysts formed by depositing catalytically active metals on single-grain quasicrystal surfaces. Using these systems, catalytic activity can be studied as a function of various parameters on atomic scale in a control way.In addition to the concerns outlined above, use of quasicrystal surface has another interest. Since quasicrystals differ from conventional crystals in various regards such as structure, symmetry, and electronic properties, these parameters of the substrate could result in the development of exotic structures.

Publications

10 25 50
 
Description Quasicrystals, materials with aperiodic long-range order, have been found in intermetallics, soft materials such as colloids and supermolecules, and also in two-dimensional monolayer
films. Here we have found the first example of three-dimensional growth of a single-element quasicrystalline film.
Exploitation Route The finding of quasicrystalline thin films of single elements opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.
Sectors Education

URL https://www.liverpool.ac.uk/physics/staff/hem-sharma/publications/
 
Description CMAC Network 
Organisation European Dynamics
Country Luxembourg 
Sector Private 
PI Contribution Knowledge and personnel excahnge
Collaborator Contribution Knowledge and personnel excahnge
Impact Knowledge and personnel excahnge
Start Year 2007
 
Description Collaboration with various institutes in Japan 
Organisation Tohoku University
Country Japan 
Sector Academic/University 
PI Contribution We have characterized the surface structure and thin films on complex metallic alloys.
Collaborator Contribution Samples used in research were grown by the partners
Impact All of these collaborations have led to over dozen publications in international journals, including recent publications in renounced nature group journal and Nano Letters.
 
Description European COST Network 
Organisation European Cooperation in Science and Technology (COST)
Country European Union (EU) 
Sector Public 
PI Contribution We are also members of the European COST Network "Intermetallic compounds as catalysts for the steam reforming of methanol".
Collaborator Contribution Knowledge and personnel exchange
Impact Two publications and one PhD
Start Year 2009