title: SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition.
abstract: Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 degrees C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10(7) particles cm(-3).
authors: Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455, USA.
authors: Adam M
authors: AM
authors: Boies
authors: Jeffrey T
authors: JT
authors: Roberts
authors: Steven L
authors: SL
authors: Girshick
authors: Bin
authors: B
authors: Zhang
authors: Toshitaka
authors: T
authors: Nakamura
authors: Amane
authors: A
authors: Mochizuki
mesh_terms: D004867:Equipment Design; D005740:Gases; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D010777:Photochemistry / Q000379:methods*; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014466:Ultraviolet Rays; D014618:Vacuum; D014835:Volatilization
chemical_list: D005740:Gases; D012821:Silanes; D012834:Silver; C040733:tetraethoxysilane; D012822:Silicon Dioxide