Synthesis of photoluminescent Si/SiO x core/shell nanoparticles by thermal disproportionation of SiO: structural and spectral characterization

摘要: Core/shell Si/SiO x nanoparticles (Si/SiO -NP) having bright red-infrared photoluminescence were obtained by a three-stage synthesis based on the thermal disproportionation of microdispersed SiO. Transformation patterns structure and spectroscopic properties material during passage through all process stages (starting from initial SiO microparticles up to -NP sols) have been revealed using Raman, ESR spectroscopy, XPS, XRD, electron microscopy. Thermal annealing (stage I) results in formation amorphous-crystalline Si nanophase matrix SiO2, as well generation paramagnetic Pb centres with concentration 4 × 1018 particles/g. At temperature, T an > 900 °C, rapid growth nanocrystal sizes takes place, and, simultaneously, centre occurs. Elimination SiO2 annealed sample etching HF II) stimulates further crystallization core, caused stress relaxation inside core when removing matrix. Functionalization nanoparticle surface III) allows obtaining core/shell their sols. Average size crystalline increases 4.7 11.1 nm an at stage I rises 350 1100 °C. relatively low an = 350 °C, monocrystalline cores are mainly formed, while an > 1100 °C, large number polycrystalline also observed. Our TEM images existence significantly different contrast even comparable sizes. We attribute that both bulk (with high contrast) flat (2D) nanocrystals course annealing.