Study on the influence of heat treatment on the crystallographic phases of nanostructured TiO2 films (original) (raw)
Related papers
2018
Titanium dioxide (TiO 2 ) thin films have innumerable applications, and the preparation of nanocomposites based on TiO 2 favors the coupling of different structures that can lead to additional or enhanced properties. The aim of this chapter is to show the preparation and characterization of TiO 2 thin films and some nanocomposites based on anatase-TiO 2 , prepared by sol-gel process using the dip-coating technique. TiO 2 thin films were prepared by sol-gel process onto borosilicate glass, steel, magnet, and silicon substrates from alcoholic starting solutions containing titanium isopropoxide, isopropyl alcohol, and acids to the control of the velocity of gelation. The doped thin films, such as SiO 2 /TiO 2 , Ag/TiO 2 , and Nb/TiO 2 , were prepared adding the dopants in a form of salts or alkoxides in starting solution. The morphological, structural, and textural characterization of the films was made using X-ray diffraction (XRD), high resolution transmission electron microscopy wit...
Structural Investigation and Properties Of Tio2 Thin Film Prepared by Sol-Gel Spin Coating
INDONESIAN JOURNAL OF APPLIED PHYSICS, 2022
We report the structural properties of TiO2 (Titanium dioxide) thin films grown using sol-gel spin coating method for temperature treatment (with temperature 50 o C and without temperature) The difference in temperature is carried out to determine changes in the surface of the sample by using heating or not. Ideally, the thickness of the TiO2 layer ranges from 10-15 μm, therefore in this study it was carried out in 5 layers. Field Emission Scanning Electron Microscopy (FESEM) consist of surface morphology, Cross-section sample, and EDX images, respectively, providing the structure of the surface. The result confirm that temperature treatment can damage the surface coating, this is proven by the shape of the crack in the coating.
Journal of Materials Science: Materials in Electronics, 2013
The influence of the preparation conditions on the structural, morphological and optical properties of TiO2 thin films deposited on silicon substrate (Si), indium tin oxide coated glass (ITO) and alkali-free borosilicate glass (AFG), respectively is studied in this work. The X-ray diffraction analysis revealed that all TiO2 samples had a polycrystalline structure. The TiO2 films coated on Si showed a mixed phase of anatase and rutile while in the case of those on ITO and AFG only the pure anatase phase was observed. The crystallite size within the TiO2 thin films varied with the calcinations temperature, solvent lateral chain and catalyst type. The optical transmittance, band gap, reflective index and porosity were strongly affected by the annealing temperature, substrate nature and solvent.
Multilayer Films from Templated TiO 2 and Structural Changes during their Thermal Treatment
Chemistry of Materials, 2008
This work is focused on synthesis, characterization, and determination of main parameters of the multilayer P123 templated TiO 2 films. The mesoporous multilayer thin films consist of TiO 2 nanoparticles on the F-doped SnO 2 (FTO) conductive glass substrates. The films were grown by implementing the protocol of supramolecular templating with the amphiphilic triblock copolymer, Pluronic P123. The templated multilayer films were manufactured by repeated dip coating followed by the thermal treatment at 350°C for 2 h after deposition of each layer. It was found that the multilayer preparation technique at 350°C has serious limitations. The structure does not further increase its specific surface area (roughness factor) after deposition of more than 3-5 layers. The new surface area added by deposition of the top layer is compensated by the reduction of the surface area lost due to the sintering of the bottom layers. The careful review of the analytical data suggests that the morphology of the P123 templated TiO 2 structure is likely the tightest arrangement of randomly positioned particles of a certain size on a given pore diameter. The bulk material consists of pores evenly formed in all directions while a denser crust is formed on the surface where the fusion was restricted in one direction at the interface with the air. Subsequent thermal treatments of the multilayer films were applied to improve the anatase crystallinity while keeping the open morphology and small particle size. The morphological changes of the mesoporous structure during the subsequent thermal treatment at 425-540°C were investigated.
Densification and Microstructural Evolution of TiO 2 Films Prepared by Sol−Gel Processing
Chemistry of Materials, 2006
Soluble precursor powders for TiO 2 -coating solutions were prepared and dissolved in solvent mixtures containing ethanol and 1,5-pentanediol in different ratios. Materials isolated by rotational evaporation of the sols (sol powders) and scraping of films deposited by dip-coating (film powders) were annealed at different temperatures and thoroughly characterized in order to investigate the influence of solvent composition and drying conditions on the film densification. Organic groups present in the precursor are partially exchanged during solvent evaporation. The chemical composition of these materials has a significant influence on the respective densification behavior and properties such as surface area and porosity. This observation can be correlated to the evolution of the crystalline polymorphs of TiO 2 , anatase, and rutile. The large area-to-volume ratio and the presence of air moisture during film drying cause significant chemical and microstructural differences between film powders and sol powders prepared by rotational evaporation. The rapid solvent evaporation in films leads to a fast densification and the inclusion of organic groups, which cause the transient presence of CO 2 entrapped in closed pores upon sintering. The conclusions drawn from the characterization of the different powders are the basis to understanding and avoiding the formation of defects on a microscopic level.
Characterization of TiO2 powders and thin films prepared by non-aqueous sol–gel techniques
Journal of Sol-Gel Science and Technology, 2009
Stable TiO 2 sols were prepared using two nonaqueous sol-gel processes with titanium n-butoxide and titanium isopropoxide, respectively. Crystallization and phase transitions of powders and thin films were studied by ex situ and in situ X-ray diffraction. For both methods, TiO 2 began to crystallize around 320°C in air. Using helium instead of air during heat treatment slowed down the crystallization and substoichiometric powders were formed. TiO 2 thin films were obtained by spin coating. The morphology of the films was evaluated using scanning electron microscopy. The films were homogeneous and transparent in the visible range. The effect of the heating atmosphere and the type of substrate was investigated.
The TiO 2 thin films have been deposited onto ultrasonically cleaned glass substrates by sol gel spin coating technique. Titanium tetra isopropoxide (TTIP), HCl and ethanol was used as a Titania (TiO 2) precursor , catalyst and solvent respectively. The spin coated films were annealed at 300 o C and 400 o C for 2h. The influence of annealing temperature on structural and optical properties of TiO 2 thin films has been studied. XRD analysis confirms that the film was found to be orthorhombic brookite structure at annealing temperature of 400 o C. Crystallite size was calculated by using Scherrer formula and it was found to be 67nm.Energy-dispersive X-ray analysis confirmed the presence of Ti and O elements in the deposited films. The SEM image of the TiO 2 films showed highly uniform, crack free and nano spherical particles of average diameter around 68nm. Optical transmittance was found to decrease with an increase in annealing temperature. The direct optical band gap of film was calculated by using Tauc's method at different annealing temperatures and was found to be in the range of 3.3eV to 3.46eV. The Urbach energy of the film annealed at different temperatures was calculated. The TiO 2 film shows high refractive index 2.52 at a wavelength of 335nm.
Elaboration and characterization of thin films of TiO2 prepared by sol–gel process
Thin Solid Films, 2002
Sol-gel TiO thin films have been obtained by a dip-coating method on a silicon substrate. Very stable sols of this oxide were 2 synthesized using the alkoxide Ti(O-nBu) in the presence of acetic acid and using acetylacetone as a chelating agent. The film 4 thickness varied from 20 to 100 nm depending on the concentration of the sol for a monolayer thin film. The structural characterization of this film on substrate Si(100) shows that the titanium oxide anatase phase is formed after heating at 400 8C for 2 h. The appearance of the rutile phase depends on the substrate used. For example, the rutile phase appeared at 700 8C in the xerogel while the presence of substrate Si(100) stabilizes the anatase phase up to 800 8C. The influence of the annealing temperature on grain size has been evidenced. Indeed, the size of the particles found equal to 4 nm for films annealed at 400 8C, increasing to around 40 nm at 800 8C.