Spectroscopy and modeling applied to the understanding of material properties

 

In order to analyze and better characterize the materials synthesized in the group (or in the context of collaborations), we have chosen to invest ourselves in forefront and complementary spectroscopies. We have associated them to calculation methods allowing us to interpret the often complex spectra. With the X-ray absorption spectroscopy (XAS) using synchrotron radiation, we can study samples which are sometimes thick such as Li-ion batteries during cycling ("operando" mode), and with a very interesting temporal resolution.

Electron energy-loss spectroscopy (EELS) is itself privileged when high spatial resolution is needed or low energy levels such as the lithium K-edge have to be measured. As for Nuclear Magnetic Resonance (NMR), it allows us, for example, to identify crystallographically inequivalent sites in a structure or study charge transfer phenomena.

In addition to these spectroscopic measurements, electronic structure calculations based on first principles (mainly DFT) help us to simulate the experimental spectra and interpret the changes both in terms of modifications in the chemical bonding and in the atomic structure (as in the case of lithium intercalation). These same calculations are also very useful to complement structural studies obtained via X-ray diffraction. We present in the following our research into four sub-themes that actually interact extensively with each other.