Crystallinity control of flame generated composite nanoparticles by laser irradiation

Continuous wave CO2 laser was irradiated on SiO2/TiO2 composite nanoparticles generating in a flame to in-situ control the crystalline phase. The laser irradiation was not only shown to transform originally amorphous composite nanoparticles into the crystalline ones, but also to control the crystallite size of TiO2 embedded in SiO2 nanoparticles by altering the irradiating laser power. X-ray diffraction analysis and transmission electron microscope analysis confirmed that the size of TiO2 anatase crystallites in silica nanoparticle increased with increasing the irradiation laser power. It was shown that the corresponding absorption edge of SiO2/TiO2 composite nanoparticles could be controlled by changing the crystallite size of TiO2 inside SiO2 nanoparticles.

Graphical abstractWe demonstrate that laser irradiation on composite nanoparticles while they are generating in a flame could not only transform originally amorphous one into crystallized one, but also control the size of crystallites depending on laser power.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Laser irradiation on particle generating flame controls nanoparticle crystallinity. ► Crystallite sizes inside host nanoparticles were controlled depending on laser power. ► Optical absorption property was tuned corresponding to the change of crystallinity.