J.Nelayah, Laboratoire Matériaux et Phénomènes Quantiques

Jeudi 4 Juillet 2013, 14h
Amphi Holweck, Esc C, 1ème etage

Applications of Spherical Aberration-Corrected Transmission Electron Microscopy in Material Science

J.Nelayah
Laboratoire Matériaux et Phénomènes Quantiques, University Paris Diderot/CNRS, UMR 7162, 75205 Paris, France.
jaysen.nelayah (arobase) univ-paris-diderot.fr

Nowadays, transmission electron microscopy (TEM) is well-established as a multipurpose high resolution analytical tool in material science and condensed-matter physics. Many revolutionary developments have been ongoing in the field of electron microscopy since the first TEM was invented in 1933 [1]. Among the various developments, the introduction of aberration-corrected electron optics in the 1990’s has been a major step forward [2]. The correction of the spherical aberration is now becoming a standard in high resolution electron microscopy and has lead to the development of electron microscopes with STEM probe correctors or TEM image correctors or even a combination of both. Material research in an aberration‐free and quantitative electron microscopy is presently a rapidly growing field. Indeed, sub‐Ångstrom imaging and sub‐electronvolt spectroscopic capabilities offered by aberration‐corrected microscopes enable the structural, chemical or optical properties of materials to be investigate with atomic precision.
I will highlight recent research undertaken at Paris Diderot university using a new generation TEM fitted with hexapole-correctors to compensate the spherical aberration (Cs) of the objective lens. When the Cs value of an objective lens is close to zero, the resolution is greatly improved and image artifacts, such as delocalization, disappear. I will show that it is then possible (i) to resolve the structure of materials in direct imaging with a resolution of about 50 picometers [3], sufficient to image individual atoms and (ii) to achieve chemical sensitivity in high‐resolution images [4]. I will illustrate the benefits of such chemical-sensitivity at atomic scale to the study of the structural and electronic properties multimetallic nanomaterials for magnetic storage and long-term development.

[1] From Nobel Lectures, Physics 1981-1990, Editor-in-Charge Tore Frängsmyr, Editor Gösta Ekspång,
World Scientific Publishing Co., Singapore, 1993
[2] M. Haider, H. Rose, S. Uhlemann, E. Schwan, B. Kabius and K. Urban, Towards 0.1 nm resolution with the
first spherically corrected transmission electron microscope, J. Electron Microscopy 47, 395-405, 1993
[3] C. Ricolleau, J. Nelayah, T. Oikawa, Y. Kohno, N. Braidy, G. Wang, F. Hue, I. Florea, V. Pierron Bohnes
and D. Alloyeau, Performances of an 80 - 200 kV microscope employing a cold-FEG and an
aberration-corrected objective lens, Journal of Electron Microscopy (2012), doi : 10.1093/jmicro/dfs072
[4] D. Alloyeau, T. Oikawa, J. Nelayah, G. Wang, and C. Ricolleau, Following Ostwald ripening in nanoalloys
by high-resolution imaging with single-atom chemical sensitivity, Appl. Phys. Lett. 101 (2012),121920

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