ST2E - Enseignant Chercheur
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Lecturer (Maître de Conférences) in Chemistry at the University of Nantes
Diplôme Ingénieur ENSIC 1991 (Nancy, France); Ph.D. 1994 (Nantes, France) ; Cavendish 1996-1998 (Cambridge, UK)
ST2E group - Institut des Matériaux Jean Rouxel - University of Nantes - Centre de MicroCaractérisation (Microscopy Center) - CNRS
Philippe Moreau is a graduate of the Ecole Nationale Supérieure des Industries Chimiques (ENSIC in Nancy, France : "Grande Ecole" specialised in Chemical Engeneering). During his PhD, his focus became redirected towards the study of materials. The subject was "Interactions in mercury intercalated TiS2 and TaS2" under the supervision of Prof. G. Ouvrard at the Institut des Materiaux Jean Rouxel in 1994. While at the Cavendish Laboratory (Cambridge, England) in his postdoctoral position under the supervision of Prof. A. Howie, he got involved in Electron Energy Loss Spectroscopy and still is involved in this field to date. He became Maître de Conférences (lecturer) at the University of Nantes in 1998 and teaches inorganic chemistry, electron microscopy and, photon and electron based spectroscopies. His current interests are in the study of lithium battery materials using EELS and electron microscopy, the development of the understanding of the low energy loss region in EELS spectra and the optimised comparison of experimental spectra with ab initio calculations.
Research Interests Statement
The powerful balance between chemistry and physics becomes increasingly obvious with each passing day, especially as far as the study of materials is concerned. Their macroscopic physical properties are often linked to their more local chemistry, i. e. the "chemical bond", which was very dear to late Prof. Jean Rouxel (founder of the Institut bearing his name). This "chemical bond" results directly from the electronic structure of the material. The determination of which, is thus a major challenge in order to get a better understanding of the material properties. In the context of the ever-growing miniaturisation of devices and the tremendous development of nanomaterials, a localised probe of this electronic structure becomes essential and Electron Energy Loss Spectroscopy in a Transmission Electron Microscope is the ideal tool (see our Microscopy Centre site). With an energy resolution of less than an eV and a probe smaller than 1 nm, EELS has revealed unrivalled possibilities See D. Muller papers . If one wants to go beyond the "finger print" analysis of the EELS spectra obtained, ab initio calculations of the spectra are necessary. These calculations, within the Density Functional Theory (DFT), are also essential tools in the visualisation of the electron density in the materials. Consequently, performing the experimental EELS technique and the theoretical DFT calculations in parallel, constitutes one of the most promising research paths in view of understanding structures and properties of new materials.
Current research interests are :
- Study of lithium batteries, using Electron Energy Loss Spectroscopy and with a special interest in the lithium K-edge
- Development of new methods of characterisation using VEELS/ our understanding of Low Energy-Loss Spectra (plasmons)
- Identification of phases, containing essentially light elements, using EELS and ab initio calculations (DFT codes, WIEN2k, ...)
Current Research Projects :
- Analysis of Lithium battery materials (different cathode composite electrodes/ anodes)
- Low energy loss spectroscopy as a structural tool of analysis of AMO3 perovskite phases
- Materials showing colossal electro resistance for non volatile memory (RRAM) (collaboration with E. Janod, L.Cario, B. Corraze)
- Study of low energy-loss spectroscopy and plasmons in nanorods (Collaboration with Jean-Luc Duvail)
- Simulation of Lithium K edges via DFT calculations taking Local Field Effects into account
Selected Publications :
- P. Moreau, N. Brun, C.A. Walsh, C. Colliex et A. Howie, "Relativistic effects in electron-energy-loss-spectroscopy observations of the Si/SiO2 interface plasmon peak", Physical Review B 56, 6774 (1997)
- P. Moreau and M.C. Cheynet, "Improved comparison of low energy loss spectra with band structure calculations : the example of BN filaments", Ultramicroscopy, 94, 293-303 (2003)
- M. Launay, F. Boucher and P. Moreau, "Evidence of a rutile-phase characteristic peak in low-energy loss spectra", Physical Review B 69, 035101 (2004)
- P. Moreau, F. Boucher, G. Goglio, D. Foy, V. Mauchamp and G. Ouvrard, "Electron Energy-Loss Spectra calculations and experiments as a tool for the identification of a lamellar C3N4 compound", Phys. Rev. B 73 195111 (2006).
- V. Stolojan, P. Moreau, M. J. Goringe, and S. Silva, "Subnanometer-resolved measurement of the tunnelling effective mass using bulk plasmons", Appl. Phys. Lett., 88, 122109 (2006)
- V. Mauchamp, F. Boucher, G. Ouvrard, and P. Moreau, "Ab initio simulation of the electron energy-loss near-edge structures at the Li K edge in Li, Li2O, and LiMn2O4", Phys. Rev. B 74, 115106 (2006).
- V. Mauchamp, P. Moreau, L. Monconduit, M-L. Doublet, F. Boucher, and G. Ouvrard, "Determination of Lithium Insertion Sites in LixTiP4 (x=2-11) by Electron Energy-Loss Spectroscopy", J. Phys. Chem. C, 111, 3996 (2007)
The high spatial resolution of EELS in a transmission electron microscope allowed us to record spectra as a function of the probe position on a BN nanofilament. Thanks to band structure calculations within the DFT as well as improved formulae, including anisotropy, thickness and relativistic effects, we managed to explain the observed evolution of the spectra. More
|Electron density plot at the A point for band n°22 in TiO2 rutile. The Ti3O unit shown above is characteristic of the rutile arrangement and can be found in other similar compounds. The low energy loss spectra of these compounds all present a peak in the 13-17 eV range, whereas the anatase phase does not. More|
|Imaginary part of the dielectric function compared to the loss function for Li and LiMn2O4. These calculations demonstrate the influence of polarisation effects when a transition metal edge is situated in the vicinity of the lithium K edge. From Vincent Mauchamp PhD thesis. More|