Development of the TKD method in a new configuration for orientation mapping at a nanometer scale.
Keywords: Transmission Kikuchi Diffraction in SEM (TKD), Electron Microscopy, Orientation Imaging Microscopy, Nanomaterials.
You will join the 3TAM group in the LEM3 and work on a research topic selected by the Laboratory of Excellence DAMAS. The 3TAM group is involved in the development of innovative methods for characterizing microstructure and crystallographic texture of materials and is expert to relate their evolution during thermo-mechanical treatments to the mechanical properties.
The TKD technique has been recently introduced as a SEM based method capable of giving orientation maps as the EBSD method but with a spatial resolution improved by up to one order of magnitude . The technique requires a specimen thin enough to be transparent to the electron beam. In the current configuration, it uses hardware and software developed for the EBSD technique.
We proposed a new configuration of the TKD where the detector is disposed horizontally on the axis of the microscope instead of being vertically positioned as in the conventional configuration. This achieves better spatial resolution and angular resolution than the ones of the current TKD configuration [2, 3, 4]. Moreover, acquisition times are shorter than in the conventional technique, because the intensity of the forward scattered electrons is much higher than that of the large angle scattered electrons.
The work will consist in two main tasks.
- The first concerns the spatial resolution of the TKD method: the lateral spatial resolution and the depth spatial resolution. In order to estimate these ones, it is essential to know where the detectable diffraction mainly occurs within the specimen thickness. First experiments on bilayer specimens have shown that it is mainly the bottom part of the specimen which contributes to the detected diffraction pattern. To analyze that more quantitatively, you will have to do Monte Carlo simulations of the electron trajectories through the specimen. It should allow to estimate what is the effect of the specimen thickness on the spatial resolution? Is there an influence to use our configuration or the conventional one? Could a change of voltage modify it?
- The second concerns the applications. As this method is new, the field of possible applications is not yet well defined. You will have to explore it. Due to its spatial resolution of few nanometers, it is well suited to study nano-structured materials. For example, ultrafine structure of metallic alloys obtained by Strong Plastic Deformation (SPD) can be characterized in order to better understand the mechanisms of grain subdivision during SPD. Another type of application concerns the electron damage sensitive materials because low voltage and low electron probe current can be used.
 R.R. Keller, R.H. Geiss, J. Microsc.245 (2012) 245-251.
 J.J. Fundenberger, E. Bouzy, D. Goran, J. Guyon, A. Morawiec, H. Yuan, Microsc. Microanal. 21 (S3) (2015) 1101-1102.
 J.J. Fundenberger, E. Bouzy, D. Goran, J. Guyon, H. Yuan, A. Morawiec, Ultramicroscopy 161 (2016) 17-22.
Requirements: Ph.D. in Materials Science or in Physics. Experimental skills and theoretical knowledge in material characterization by electron microscopy, particularly in SEM + EBSD and TEM. Experience in preparation of TEM specimens by FIB and Monte-Carlo simulations would be appreciated. A good level of written English is essential.
Deadline: June 30 2016. The following documents must be sent by e-mail to Prof. Emmanuel Bouzy : cover letter describing your research interest and why you are suitable for this position (maximum 1 page) – CV and list of publications – Names, e-mail addresses, and telephone numbers for two academic references.
Expected start date and duration: as soon as possible from March 2016 for one year. (possible extension for one year)
Net salary: 2200 Euros.
Further information : E. Bouzy firstname.lastname@example.org Tel : +33 (0)3 87 31 53 96
J.-J. Fundenberger email@example.com Tel : +33 (0)3 87 31 53 27
LEM3 UMR CNRS7239 – Université de Lorraine – Ile du Saulcy – 57012 METZ Cedex 01 – France.