Synthesis method and substrate influence on TiO 2 films doped with low vanadium content (original) (raw)
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International Journal of Modern Physics B, 2010
Pure titania (TiO2) nanopowders and TiO2 doped with 10 mol % of vanadium ions (V3+) are synthesized by sol-gel method. The dependence of structural characteristics of nanopowders on synthesis conditions is investigated by X-ray diffraction and Raman spectroscopy. Very intensive modes observed in Raman spectra of all nanopowders are assigned to anatase phase of TiO2. Additional Raman modes of extremely
Applied Surface Science, 2010
Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO 2 thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO 2 thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO 2 thin films. The results show that the TiO 2 thin films crystallize in anatase phase between 400 and 800 • C, and into the anatase-rutile phase at 1000 • C, and further into the rutile phase at 1200 • C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO 2 thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 • C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.
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Journal of Non-Crystalline Solids, 2007
Nanocrystalline thin films of titanium dioxide have been fabricated on glass and silica substrates from partially hydrolyzed precursor solution. These films were subjected to heat treatment for 1 h at temperatures 100, 200, 300, 400, 500, 600, 700, 800 and 900°C and characterized by XRD, SEM, XPS and optical techniques. As deposited films are found to be amorphous and also contain hydroxyl and organic functional groups. Films heat treated above 100°C do not contain hydroxyl and organic functional groups. Microcrystalline behavior is observed in the films heat treated above 300°C. Crystallite size increases from $5 to 50 nm as sintering temperature is increased from 300 to 700°C. Formation of anatase phase with c-axis length 7.03 Å is observed in the films annealed up to 700°C. These films peel off from the substrate beyond 700°C annealing temperature. Density as well as refractive index of the films increases with increase in annealing temperature up to 700°C. Refractive index is found to show Cauchys behavior. Transmission better than 70% is observed in the visible range. There is a strong absorption around 370 nm, which is attributed to band gap absorption of the material.
The influence of annealing temperature on the structure, optical and electrical property of TiO 2 thin films with (101) preferential orientation were deposited on glass substrates by sol-gel technique has been studied. As-deposited films were amorphous, and the XRD studies showed that the formation of anatase phase was initiated at annealing temperature close to 400 °C. The grain size of the film annealed at 550 °C was about 22 nm. The transmission spectra, recorded in the UV visible range reveal a relatively high transmission coefficient (~70%) in the obtained films. The transmittance data analysis indicates that the optical band gap (E g ) is closely related to the annealing temperature, an indirect band gap ranging from 3.43 eV to 3.04 eV was deduced. The electrical resistivity measurement that were carried out in function of the annealing temperature showed a sharp decrease in resistivity was found to be 0.0802 .cm.
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Journal of Materials Science: Materials in Electronics, 2016
A dip-coating technique was employed to prepare anatase phase of titania thin films. Fluorine doped tin oxide substrates were used to prepare titania thin films. The samples were annealed at 550°C for 18 h. X-ray diffraction results revealed the amorphous and anatase phases of TiO 2 for as-synthesized and annealed samples, respectively. The crystallite size of anatase TiO 2 thin films was almost 25 nm for annealed samples. UV-visible confirmed the energy band gap 3.86 and 3.64 eV for as-prepared and calcinated titania thin films. The reduction in the energy band gap could be due to the change in crystallization and agglomeration of small grains after calcination. The morphology of the prepared films was investigated by field emission scanning electron microscopy which demonstrated the agglomeration of spherical particles of TiO 2 with average particle size of about 30 nm. The molecular properties (chemical bonding) of the samples were investigated by means of Fourier Transform Infrared (FTIR) spectroscopy. FTIR analysis exhibited the formation of titania, functional group OH, hydroxyl stretching vibrations of the C-OH groups, bending vibration mode of H-O-H, alkyl C-H stretch, stretching band of Ti-OH, CN asymmetric band stretching, and C=O saturated aldehyde.
Structural and Optical Properties of TiO2 Thin Films Prepared by Sol-Gel Process
Titanium oxide (TiO2) thin films were synthesized by sol–gel process: titanium tetraisopropoxide was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The resulting sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 oC (2 h). The structural, morphological and optical properties of the prepared films were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The Optical Waveguiding properties such as refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 632.8 nm by m-lines spectroscopy as a function of the elaboration parameters. The films exhibit diffraction pattern consistent with an anatase phase and the TiO2 planar waveguides are multimodes and demonstrate propagation losses as low as 0.3 dB/cm for annealing temperature 350 and 500 °C, respectively.
Optical and Microstructure behavior on Vanadium doped (V-TiO2) oxide films using magnetron reactive sputtering, 2020
Vanadium doped Titanium dioxide (V-TiO2) thin films were prepared using DC magnetron sputtering method. The samples were subjected to analysis of X-ray diffraction, SEM and optical studies. The XRD films revealed the crystallographic lattice planes such as (101), (200) etc. We report two observations, one was variation of partial O2 pressure inside the chamber and other was temperature dependent. The broad peaks were assigned to 2θ=25.313º for (101) plane, 2θ=37.684º for (112) plane and 2θ=48.084º for (200) plane and intensity of interfacial planer planes was magnified with the temperature. SEM Micrographs show that tracks of annealed metal TiO2 films were developed significantly and film phases were distributed uniformly with the temperature variation. EDAX reviled that the mean ratio of Ti:V was 52.35:47.65 and an evaluated Ti/V ratio was 1.10. The average size of the crystallite was also determined using Scherer formula and the structural parameters were determined on the basis of temperature dependent and the present work indicates the percent of transmission for electronic applications.
Vanadium Doped Sol-Gel TiO2 Coatings
Journal of Sol-gel Science and Technology, 1998
A study of the experimental conditions required to obtain vanadium doped sol-gel TiO2 coatings is presented. Tetraethyl orthotitanate was employed as the TiO2 source and VCl3, VOSO4 · H2O and VOSO4 dissolved H2SO4 where employed as vanadium sources.
2011
TiO 2 thin films were deposited on glass substrates by sol-gel method. Nanocrystalline TiO 2 thin films were prepared at ambient conditions and titanium tetraisopropoxide [C 12 H 28 O 4 Ti] was used as a Ti-precursor. The effect of annealing temperature on optical properties of nanocrystalline TiO 2 thin films was studied. The as-deposited films were dried at 100 0 C for 1 hr. The films formed were further heated in temperature between 200 and 500 0 C for 1 hr. The films were characterized by different techniques: XRD, UV-visible spectroscopy, FTIR spectroscopy and FESEM. The characterization studies revealed that the films are crystallized as anatase phase and nano-structured with better optical properties α = 0.89 as compared to reported data. The optical measurement showed the indirect band gap between 3.31 and 3.35 eV with corresponding crystallite sizes between 8.9 and 3.7 nm. The FESEM image of film annealed at 400 0 C showed spherical nanocrystalline structure of TiO 2 particles. The crystallite sizes obtained from FESEM image are found to be between 30 and 100 nm. It is also observed that refractive index of the film increases with increasing the annealing temperature. The smaller crystallite size gives larger band gap due to quantum size effects.