Solar preparation of SiOx (x ≈ 1) nanopowders from silicon vaporisation on a ZrO2 pellet. XPS and photoluminescence characterisation

SiOx nanoparticles were prepared by vaporisation and condensation of melted silicon droplets put on zirconia pellets in a solar reactor at the focus of a 2 kW solar furnace. The size of the grains were nanometric, generally included in the range 20-40 nm, and the O/Si atomic ratio values were close to stoichiometry (O/Si ≈ 1 ± 0.2). XPS, DRX and TEM analyses show that these nanoparticles are amorphous with various silicon chemical environments which can be described as constituted with polysubstituted Si-(O4−nSin) tetrahedral configurations. The estimated oxygen atomic concentrations for these nanoparticles was in good agreement with thermodynamic equilibrium calculations for the system ZrO2-Si at high temperature. The predominant gaseous species is the SiO molecule. The SiOx nanoparticles present photoluminescence property similar to those currently reported for electrolytic porous silicon.