ABSTRACT
Nanocrystalline titanium dioxide (TiO2) thin films on silicon wafer substrates were prepared by sol-gel spin coating process. The prepared thin films were treated with electron beam (1.1 MeV, 300 kGy) at air atmosphere. The effects of electron-beam (EB) irradiation on the structural and optical properties of the TiO2 thin films were investigated. The structures of all the TiO2 thin films by XRD analysis showed an anatase phase, and the phase remained unchanged within the investigating range of EB treatment. The thickness of the titania thin film decreased slightly with EB treatment whereas the porosity increased. The EB treatment of TiO2 thin film can increase the proportion of Ti3+ in Ti2p at the thin film surface. The optical transmittance of the film in the wavelength ranges of above 380 nm increased after the EB treatment while its refractive index decreased with increasing EB dose. Therefore, improvement of the optical properties could be due to the change in both surface chemistry and morphology of the TiO2 thin films affected by EB irradiation.
ABSTRACT
Pt nanoparticle-doped titanium dioxide (Pt/TiO2) thin films were prepared on a silicon wafer substrate by sol-gel spin coating process. The prepared thin films were treated with electron beam (EB at 1.1 MeV, 100, 200, 300 kGy) at air atmosphere. The effect of EB-irradiation on the composition of the treated thin films, optical properties and morphology of thin films were investigated by various analytical techniques such as X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The crystal structure of the TiO2 layer was found to be an anatase phase and the size of TiO2 particles was determined to be about 13 nm. Pt nanoparticles with diameter of 5 nm were observed on surface of the films. A new layer (presumed to be Pt-Ti complex and/or PtO2 compound) was created in the Pt/TiO2 thin film treated with EB (300 kGy). The transmittance of thin film decreased with EB treatment whereas the refractive index increased.
ABSTRACT
Silver-polyphenylsilane nanocomposites have been effectively prepared by the dehydrocoupling reaction of phenylsilane (PS, PhSiH3) to polyphenylsilane (PPS, [PhSiH]n) in the presence of silver nitrate. The one-step reduction of Ag(+1) nitrate to stable Ag(0) nanoparticles is mediated by PS, resulting in the formation of Ag-PPS composites. The Ag-PPS nanocomposites were characterized by various analytical techniques such as XRD, TEM, FE-SEM, and solid-state UV-vis. TEM and FE-SEM data clearly show that the silver nanoparticles with the size of < 20 nm are well dispersed throughout the PPS matrix in the nanocomposites. XRD patterns are consistent with those for fcc crystalline silver. The size of silver nanoparticles increased with increasing the relative molar concentration of silver salts added. It was found that in the absence of PS, most of the silver nanoparticles undergo macroscopic precipitation by aggregation, indicating that PPS is essential to stabilize the silver nanoparticles by the complexation of Si-H to the silver metal centers.