Science

Programme "Scientific projects"

Mechanical behaviour of two-dimensional crystals: the case of graphene

Department of Material Science, University of Patras Collaborating

2011

Graphene is a two-dimensional crystal with the thickness of one atom. This material has attracted great interest within the scientific community due to its extraordinary properties, which differ from those of three-dimensional materials. Graphene was isolated for the first time by Novoselov and Geim (University of Manchester, UK), who were awarded for their work the Nobel Prize in Physics in 2010. Professor Konstantin Novoselov is in fact a member of the research team of the current study.
The research team focused its efforts on the study of the mechanical response of both monolayer and bilayer graphene by means of suitable micro-devices. Identification of the number of layers in each graphene flake and the monitoring of its mechanical response was accomplished with the use of an inelastic scattering technique (Raman spectroscopy) through the changes occurring in certain vibrational states of the material.
The results of this study were presented in the scientific literature for the first time. It was shown that a perfect two-dimensional crystal behaves like a thin plate under a uniaxial compressive load. The splitting of the 2D Raman peak under stress as a result of a double resonance process and of the peculiar electronic band structure of graphene was observed experimentally and was explained theoretically. It was also observed that a uniaxial tensile deformation can lead to the appearance of an energy gap in bilayer graphene. The isolated graphene flakes were produced by the method of chemical vapour deposition of camphor, a technique that was developed specifically for this study, and also through mechanical exfoliation of graphite.
The results of this study are expected to contribute to the efforts made towards the fabrication of novel functional graphene-based materials and shed light on the development of new electronic devices by spatially controlled strain engineering.

PHOTO GALLERY

Coordinator:

Constantinos Galiotis, Professor, Department of Material Science, University of Patras Collaborating Faculty Member, Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology - Hellas

Project Team:

Konstantinos Papaggelis, Assistant Professor, Department of Material Science, University of Patras

John Parthenios, Researcher, Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology - Hellas

Dimitrios Tassis, Postdoctoral collaborator, Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology - Hellas

Konstantin Novoselov Professor, School of Physics and Astronomy, University of Manchester

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