Porous silica nanoparticles are considering good systems for drug cargo and liquid separation. In this work we studied the release of rhodamine 6G (Rh6G) from solid and porous silica nanoparticles. Solid and porous SiO2 spheres were prepared by sol-gel method. Nanoporous channels were produced by using a surfactant that was removed by chemical procedure. Rh6G was incorporated into the channels by impregnation. The hexagonal structure of the pores was detected by XRD and confirmed by HRTEM micrographs. Rh6G released from the particles by stirring them in water at controlled speed was studied as function of time by photoluminescence. Released ratio was faster in the solid nanoparticles than in the porous ones. In the last case, a second release mechanism was observed. It was related with rhodamine coming out from the porous.
Amorphous and crystalline TiO2 and TiO2:Eu3+ thin films were synthesized by the sol–gel process at room temperature. The films were spin-coated on glass substrates. The samples were calcined at 400°C, 500°C for 2h to produce crystalline films. The films were characterized using X-ray diffraction, infrared spectroscopy, scanning
electron microscopy and transmission electronic microscopy and UV-Vis absorption spectroscopy. An anatase phase
was determined in the samples calcined at 500°C. Film thickness was calculated by SEM. Absorption peaks were
located between 293-298 nm which are due to the titania host. It can be observed that this peak position depends of
the calcination temperature. Band gap was calculated, and it indicates a non-linear behavior of the samples.
Photoconductivity studies were performed on amorphous and crystalline films. The experimental data were fitted with
curve lines to order square at darkness and under illumination (310 nm and 515 nm). This indicates a non-ohmic
behavior. Transport parameters, photovoltaic and photoconductive; were calculated for both samples.
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