Nanocrystalline titanium oxide thin films prepared by sol-gel process

Abstract

Crystalline films of pure titanium oxide have been prepared on soda lime slide glasses by sol-gel process and dip-coating. The definition of various parameters such as chemical concentration, viscosity, catalyst type and withdrawal speed led to the preparation of transparent, crystalline and adherent coatings with hydrophobic characteristics. Their crystalline structure was evaluated as anatase phase by low angle X-ray diffraction. Thicknesses were measured by perfilometry, and the refractive indices were determined from transmittance spectrum taking into consideration the layers deposited onto the two sides of the substrate. Porosity was also estimated by UV-visible spectroscopy by using the Lorentz -Lorenz equation. The average grain size was evaluated by atomic force microscopy. The thicker and denser films presented hydrophobicity, which decreased when the film porosity increased.

Thin layer photocatalysts of TiO2-Ag composites

“…This difference could also be observed in the colour of the samples: TiO 2 -Ag coatings were almost completely transparent, while TiO 2 /Ag coatings showed a deeper grey colour. The TiO 2 /Ag samples also show a peak around 506 nm, which can be attributed to the surface plasmon absorption of Ag particles [27]. The effective refractive index (n), layer thickness (d) and porosity (P) values of the coatings determined from the transmittance data can be seen in Table 1.…”

Voltammetric sensor for theophylline using sol–gel immobilized molecularly imprinted polymer particles

“…Though signal intensity was seen to be related to the final gel thickness, an optimised deposited volume of 10 μL on the graphiteepoxy composite electrode was chosen as larger deposition volumes were seen to increase the instance of crack formation on the gel surface, a finding consistent with the literature [35]. Though it is possible to negate the instance of crack altogether as well as to achieve extremely high film uniformity via multiple layered depositions [36], the signal augmentation that was seen with the single deposition was not replicated when multiple layers were built up on the electrode surface. The use of high-potential voltammetric cycling or sustained high voltage pre-treatments were seen to be detrimental to the structural integrity of the sol-gel and thus obliged the subtraction of interfering background currents prior to each measurement.…”

Thickness and annealing effects on thermally evaporated InZnO thin films for gas sensors and blue, green and yellow emissive optical devices

“…Annealing temperature or heat treatment is very effective to improve the electrical and optical properties [6e9]. Also, annealing effect can enhance the film properties, such as crystal quality, electric and luminescence behavior by improvement of crystallinity of the films and increase in grain sizes [10,11]. Poor crystalline quality may cause a reduction in the relaxation time and mobility as a result of increased point defects, grain boundaries and lattice distortion [12,13].…”