Formation and stability of different Na-Si phases predicted from DFT calculations using high pressure-high temperature in-situ experiments

For energy applications, there is need to develop materials made of abundant, cheap and non toxic elements such as Si and Na. In previous in-situ high pressure – high temperature (HP-HT) x-ray diffraction (XRD) experiments at the ESRF, we have observed several new and unknown Na-Si phases, some of which can be recovered at ambient conditions. From those data, we have been successful in identifying one of these new phases and have a high FoM lattice for another, which requires further work for complete resolution. These results, and that the Na-Si phase diagram is still relatively unexplored, leads to this proposal to further investigate the HP-HT Na-Si phase diagram and identify potential new materials for energy applications using in-situ HP-HT X-Ray diffraction at the ID06-LVP ESRF beamline. This forms part of an on-going ANR project, of which the in-situ element is key, between our Institutions, which supports several postdoc and PhD positions.