Pressure-Induced Structural transformations of the Zintl phase sodium silicide

Raul Quesada Cabrera (1, 2) , Ashkan Salamat (1, 2, 3) , Oleg I. Barkalov (1, 2, 4) , Olivier Leynaud (5) , Peter T. Hutchins (1, 2) , Dominik Daisenberger (1, 2, 6) , Denis Machon (7) , Andrea Sella (1, 2) , Dewi W. Lewis (1, 2, 8) , Paul F. Mcmillan (1, 2)

1 Department of Chemistry, UCL
2 Centre for Materials Research, UCL
3 ESRF - European Synchrotron Radiation Facility
4 Institute for Solid State Physics
5 NEEL - X'Press - X'Press : diffraction et hautes pressions
6 Membrane Protein Laboratory, Diamond Light Source
7 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
8 UCL - University College of London [London]

The high-pressure behaviour of NaSi has been studied using Raman spectroscopy and angle-dispersive synchrotron X-ray diffraction to observe the onset of structural phase transformations and potential oligomerisation into anionic Si nanoclusters with extended dimensionality. Our studies reveal a first structural transformation occurring at 8-10 GPa, followed by irreversible amorphisation above 15 GPa, suggesting the formation of Si-Si bonds with oxidation of the Si(-) species and reduction of Na(+) to metallic sodium. We have combined our experimental studies with DFT calculations to assist in the analysis of the structural behaviour of NaSi at high pressure.

Mots clés: Pressure-induced amorphisation; Raman spectroscopy; Density functional calculation; Sodium silicide; Zintl phase; High-pressure transition; Synchrotron X-ray diffraction

Domaines: Matériaux

Raul Quesada Cabrera, Ashkan Salamat, Oleg I. Barkalov, Olivier Leynaud, Peter T. Hutchins, et al.. Pressure-Induced Structural transformations of the Zintl phase sodium silicide. Journal of Solid State Chemistry, 2009, 182 (9), pp.2535-2542. ⟨10.1016/j.jssc.2009.06.037⟩. ⟨hal-00993262⟩