Phase segregation in binary SiO_2/TiO_2 and SiO_2/Fe_2O_3 nanoparticle aerosols formed in a premixed flame

摘要

Binary SiO_2/TiO_2 and SiO_2/Fe_2O_3nanoparticle (diameter < 100 nm) aerosols of varying mole ratiosof Ti or Fe to Si were generated in a premixed Bunsen-type aerosolflame reactor. The distribution of species within the particles wasinvestigated using transmission electron microscopy, electronenergy loss spectrometry, x-ray diffraction, and Fourier transforminfrared spectroscopy. Phase segregation was observed to varyingdegrees in qualitative agreement with segregation expected frombinary phase diagrams for the bulk systems. Differences betweenthe SiO_2/TiO_2 and SiO_2/Fe_2O_3 systems can be explainedby considering the variation in the thermodynamically stableliquid-phase solubility and differences in the ability of iron andtitanium ions to substitute for silicon ions in the network structure.