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1

TiO2 thin films for dyes photodegradation  

International Nuclear Information System (INIS)

The aim of the present study is to investigate the influence of the TiO2 specific surface (powder, film) on the photocatalytic degradation of methyl orange. Porous TiO2 films were deposited on transparent conducting oxide substrates by spray pyrolysis deposition. The films were characterized by X-ray diffraction (XRD), Scanning Electronic Microscopy, and the UV-Vis spectroscopy. The XRD spectra of nanoporous TiO2 films revealed an anatase, crystalline structure that is known as the most suitable structure in photocatalysis. The average thickness of the films was 260 nm and the measured band gap is 3.44 eV. The influence of the operational parameters (dye concentration, contact time) on the degradation rate of the dye on TiO2 was examined. There were calculated the kinetic parameters and the process efficiency. Using thin films of TiO2 is technologically recommended but raises problems due to lowering the amount of catalyst available for the dye degradation

2007-06-04

2

Electrical characteristics of TiO2 thin films  

International Nuclear Information System (INIS)

Thin film of titanium is deposited by heating, Joule method in oxygen gas, and investigated on electrical characteristics. The target material of this study is titanium sponge. After this material is evaporated on glass slide, aluminium layer evaporated. This paper reports the conduction of titanium thin film on Schottky emission and space-charge limited-flow under various temperatures. The results are as follows: electrical current is proportionate to the exponent of the square root of voltage in D.C. electric conductibility, TiO2 thin film. Electron emission increases according to the rise of circumference temperature, but the rate of increase diminishes drastically more than 1580C on TiO2 thin film. The metal-insulator thin film TiO2 results fall into two categories on A.C. characteristics. The resistance decreases according to the rise of frequency in insulator. The resistance of transmitter in little value increases according to the rise of frequency. (author)

1980-01-01

3

Superhydrophilicity of TiO2 nano thin films  

International Nuclear Information System (INIS)

Full text: Among the several oxide semiconductors, titanium dioxide has a more helpful role in our environmental purification due to its photocatalytic activity, photo-induced superhydrophilicity, and as a result of them non-toxicity, self cleaning, and antifogging effects. After the discovery of superhydrophilicity of titanium dioxide in 1997, several researches have been performed due to its nature and useful applications. The superhydrophilicity property of the surface allows water to spread completely across the surface rather than remains as droplets, thus making the surface antifog and easy-to-clean. The distinction of photo-induced catalytic and hydrophilicity properties of TiO2 thin films has been accepted although, the origin of hydrophilicity property has not been recognized completely yet. TiO2 thin films on soda lime glass were prepared by the sol-gel method and spin coating process. The calcination temperature was changed from 100 to 550 C. XRD patterns show increasing the content of polycrystalline anatase phase with increasing the calcination temperature. The AFM results indicate granular morphology of the films, which particle size changes from 22 to 166 nm by increasing the calcination temperature. The RBS, EDX and Raman spectroscopy of the films show the ratio of Ti:O?0.5, and diffusion of sodium ions from substrate into the layer, by increasing the calcination temperature. The UV/Vis. spectroscopy of the films indicates a red shift by increasing the calcination temperature. The contact angle meter experiment shows that superhydrophilicity of the films depends on the formation of anatase crystal structure and diffused sodium content from substrate to the layer. The best hydrophilicity property was observed at 450 C calcination temperature, where the film is converted to a superhydrophilic surface after 10 minutes under 2mW/cm2 UV irradiation. TiO2 thin film on Si(111), Si(100), and quartz substrates needs less time to be converted to superhydrophilic surface rather than glass and polycrystalline Si substrates. Our results are consistent with the idea that UV-induced wetting of TiO2 surface is caused by the removal of hydrophobic layers of hydrocarbons by TiO2-mediated photo-oxidation, which leads to the attractive interaction of water with clean TiO2 surface. (authors)

2007-09-01

4

Preparation and characterization of nanocrystalline porous TiO2/WO3 composite thin films  

International Nuclear Information System (INIS)

TiO2 materials possessing not only photocatalytic but also electrochromic properties have attracted many research and development interests. Though WO3 exhibits excellent electrochromic properties, the much higher cost and water-sensitivity of WO3 as compared with the TiO2 may restrict the practical application of WO3 materials. In the present study, the feasibility of preparing nanocrystalline porous TiO2/WO3 composite thin films was investigated. Precursors of sols TiO2 and/or WO3 and polystyrene microspheres were used to prepare nanocrystalline pure TiO2, WO3, and composite TiO2/WO3 thin films by spin coating. The spin-coated thin films were amorphous and, after heat treating at a temperature of 500 oC, nanocrystalline TiO2, TiO2/WO3, and WO3 thin films with or without pores were prepared successfully. The heat-treated thin films were colorless and coloration-bleaching phenomena can be observed during cyclic voltammetry tests. The heat-treated thin films exhibited good reversible electrochromic behavior while the porous TiO2/WO3 composite film exhibited improved electrochromic properties

2006-01-03

5

Photocatalytic properties of porous TiO2/Ag thin films  

International Nuclear Information System (INIS)

In this study, nanocrystalline TiO2/Ag composite thin films were prepared by a sol-gel spin-coating technique. By introducing polystyrene (PS) spheres into the precursor solution, porous TiO2/Ag thin films were prepared after calcination at a temperature of 500 deg. C for 4 h. Three different sizes (50, 200, and 400 nm) of PS spheres were used to prepare porous TiO2 films. The as-prepared TiO2 and TiO2/Ag thin films were characterized by X-ray diffractometry (XRD) and by scanning electron microscopy to reveal structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. When PS spheres of different sizes were introduced after calcination, the as-prepared TiO2 films exhibited different porous structures. XRD results showed that all TiO2/Ag films exhibited a major anatase phase. The photodegradation of porous TiO2 thin films prepared with 200 nm PS spheres and doped with 1 mol% Ag exhibited the best photocatalytic efficiency where ? 100% methylene blue was decomposed within 8 h under UV exposure

2008-02-29

6

Structural analysis of TiO2 and TiO2-Ag thin films and their antibacterial behaviors  

Science.gov (United States)

TiO2 (rutile and anatase) thin films was first prepared using reactive sputtering, in an Ar+O2 plasma. In the 2nd stage of the experiment, various amounts (3, 7, and 10 at. %) of Ag was doped into the rutile film in order to form TiO2-Ag thin films. These films were annealed for one hour in Ar atmosphere, at 300, 400, and 500 °C. The films' structures were then examined using X-ray diffractometry. FESEM (field-emission scaning electron microscopy) was used to investigate the surface emergence of Ag particles. As for the examination of optical band gaps and absorption of these films, UV-Vis-NIR photometer was used. The results show that, in as-deposited condition, the addition of Ag might disrupt the growth of crystalline structure and cause the formation of amorphous films. After annealing, it is found that the structure tends to become anatase phase which is a metastable phase between amorphous titanium oxide and rutile. More importantly, the absorption of the Ag-doped films would be enhanced in the visible-light range. Some of the enhancement is clearly due to plasmon resonance effect. The Ag-doped samples have shown some antibacterial effect in dark. When irradiated with light, the samples show a synergistic behavior combining the bactericidal effect of Ag ions and photocatalytic effect of TiO2.

Hsieh, J. H.; Yu, R. B.; Chang, Y. K.; Li, C.

2012-01-01

7

Structural and optical properties of electrohydrodynamically atomized TiO2 nanostructured thin films  

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In this paper, we report an alternate technique for the deposition of nanostructured TiO2 thin films using the electrohydrodynamic atomization (EHDA) technique using polyvinylpyrrolidone (PVP) as a stabilizer. The required parameters for achieving uniform TiO2 films using EHDA are also discussed in detail. X-ray diffraction results confirm that the TiO2 films were oriented in the anatase phase. Scanning electron microscope studies revealed the uniform deposition of the TiO2. The purity of the films is characterized by using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), confirming the presence of Ti-O bonding in the films without any organic residue. The optical properties of the TiO2 films were measured by UV-visible spectroscopy, which shows that the transparency of the films is nearly 85% in the visible region. The current-voltage ( I- V) curve of the TiO2 thin films shows a nearly linear behavior with 45 m? cm of electrical resistivity. These results suggest that TiO2 thin films deposited via the EHDA method possess promising applications in optoelectronic devices.

Choi, Kyung-Hyun; Duraisamy, Navaneethan; Muhammad, Nauman Malik; Kim, Inyoung; Choi, Hyunseok; Jo, Jeongdai

2012-06-01

8

Photocatalytic activity of TiO2 thin film non-uniformly doped by Ni  

International Nuclear Information System (INIS)

The thin films of TiO2 doped by Ni non-uniformly were prepared by a modified dip-hoisting process of sol-gel method. The transmittance, absorbency, photocurrent and open-circuit potential of the thin films were studied by UV-vis spectrophotometer and electrochemical workstation. The activity of thin films was characterized by photocatalytic degradation of aqueous methyl orange under UV irradiation. The results showed that the photocatalytic activity of TiO2 thin films can be remarkably enhanced by Ni non-uniformly doping compared with the pure ones, while that of the uniformly doped can only be improved a little. The transmittance of the TiO2 thin films doped by Ni uniformly and non-uniformly doping showed 'blue shift' and 'red shift', respectively. The absorbency of the non-uniformly doped extended to 'red shift'. Under UV irradiation, the non-uniformly doped TiO2 thin films show higher open-circuit potential and photocurrent compared with that of the pure ones, which demonstrated that the photogenerated electron-hole pairs were effectively separated. And the electrode bias influenced the photocurrent of Ni non-uniformly doped TiO2 thin films greatly, which verified the structure of p-n junction. The photocatalytic activity mechanism of the non-uniformly doped TiO2 was discussed by p-n junction theory

2006-05-10

9

Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering  

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Full Text Available We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2 thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C. The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD, the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior.

Francisco López-Huerta

2014-05-01

10

Micro-structuring of TiO2 thin films by laser-assisted diffraction processing  

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Thin films of TiO2 are deposited by magnetron sputtering on glass substrate and are irradiated by UV radiation using a KrF excimer laser (248 nm). These thin films are patterned with a razor blade placed on the way of the radiation just in front of the TiO2 thin film. Just near the edge of the razor blade on the thin film, diffraction lines are observed, resulting in the ablation of the film. These patterns are characterized by optical microscopy, mechanical profilometry. Diffraction up to th...

2007-01-01

11

Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping  

Science.gov (United States)

Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

Liu, Zhifeng; Wang, Yun; Peng, Xinli; Li, Yabin; Liu, Zhichao; Liu, Chengcheng; Ya, Jing; Huang, Yizhong

2012-04-01

12

Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping  

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Full Text Available Hydrophilic Cu–TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

Zhifeng Liu, Yun Wang, Xinli Peng, Yabin Li, Zhichao Liu, Chengcheng Liu, Jing Ya and Yizhong Huang

2012-01-01

13

Nanostructured TiO2 thin films for field emission and sensor applications  

Science.gov (United States)

Thin films consisting TiO2 nanoparticles were synthesized by a cost effective ultrasonic spray pyrolysis technique on Si(100) and glass substrates at temperatures of 350 and 450 °C. The films were found to be anatase phase of TiO2 from GIXRD and Raman studies. Effect of substrate temperature on growth process was monitored using FESEM technique. The substrate temperature influenced the morphology of the films and also on the field emission properties. The asdeposited semi-conducting TiO2 films were investigated for the utilization of alcohol sensor at room temperature.

Raut, N. C.

2012-10-01

14

Buckle delamination of textured TiO2 thin films on mica  

International Nuclear Information System (INIS)

We present the growth of textured TiO2 thin films on muscovite mica using pulsed laser deposition. Atomic force microscopy, scanning electron microscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were used to characterize the TiO2 films. Quasi-periodic wavy and comb-like buckles were observed. Below a critical thickness of about 25 nm, TiO2 films were relatively smooth, and buckles began to form when the nominal thickness of TiO2 films was larger than 25 nm. Co-existence of wavy and comb-like quasi-periodic buckles was observed when the nominal thickness of TiO2 films was larger than 100 nm. The film stress is compressive due to the competition of the tensile stress from the lattice mismatch and the growth stress. The buckle delamination occurred when the compressive stress overcome the adhesion strength of the TiO2 films on mica. A value of adhesion strength around 0.9 MPa for TiO2 on mica is obtained. The symmetric domains of buckles are assigned to the anisotropic lattice mismatch for TiO2 on mica

2005-10-01

15

Effect of ZnFe2O4 doping on the optical properties of TiO2 thin films  

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Amorphous TiO2 thin films and ZnFe2O4-doped TiO2 composite films were deposited by radio frequency magnetron sputtering. The effect of ZnFe2O4 doping on the optical properties of TiO2 thin films was reported. Our results show that the absorption edge of TiO2 thin films and composite films exhibits a blueshift with decreasing annealing temperature. The absorption edge of composite films has moved to a visible spectrum range and a very large redshift occurs in comparison with TiO2 thin films. An enhanced photoluminescence was observed in ZnFe2O4-doped anatase TiO2 thin films at room temperature.

Li, Guang-hai; Wu, Yu-cheng; Zhang, Li-de

2001-02-01

16

Development of multilayered nanocrystalline TiO2 thin films for photovoltaic application  

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Nanocrystalline multilayered thin films of TiO2 have been prepared to achieve high transparency in the wavelength range of 400-800 nm having good adhesion to the ITO substrate. TiO2 sol is synthesized through wet chemical route for making thin films by dip coating process. The layer wise optical characterization reveals higher band gap values of 3.45 eV, 3.32 eV for 2-layered and 3-layered films respectively while further depositions of thin layers followed by annealing treatment shows that the value of band gap approaches towards the bulk TiO2 considerable decrease in band gap with increase in thickness due to successive coatings of thin film is observed because of growth in crystal size as well as improving the grain contact on successive annealing treatments. Photo-conversion efficiency of the assembled solar cell is in the order of 7%.

Usha, K.; Mondal, B.; Sengupta, D.; Das, P.; Mukherjee, K.; Kumbhakar, P.

2014-04-01

17

Photocatalytic properties of nanocrystalline TiO2 thin film with Ag additions  

International Nuclear Information System (INIS)

In the present study, nanocrystalline TiO2/Ag composite thin films were prepared by a sol-gel spin coating technique. While, by introducing polystyrene (PS) microspheres, porous TiO2/Ag films were obtained after calcining at a temperature of 500 oC. The as-prepared TiO2 and TiO2/Ag thin films were characterized by X-ray diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methylene blue under UV irradiation. After 500 oC calcination, the microstructure of PS-TiO2 film without Ag addition exhibited a sponge-like microstructure while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Meanwhile, coalescence of nanocrystalline anatase-phase TiO2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO2 doped with 1 mol% Ag exhibited the best photocatalytic efficiency where 72% methylene blue can be decomposed after UV exposure for 12 h

2006-01-03

18

Raman spectra of TiO2 thin films deposited electrochemically and by spray pyrolysis  

International Nuclear Information System (INIS)

In this paper we present our experimental results concerning the fabrication of TiO2 thin films by spray pyrolysis and electrochemical deposition method onto different substrates - Corning glass, Si and optical fibers. The surface morphology of the TiO2 thin films have been investigated by Atomic Force Microscopy. Raman shift spectra measurements have been done for the optical characterization of the fabricated titania thin films. The post-growth rapid photothermal processing (RPP) at temperatures of 100-800 degrees Celsius for 1-3 min have been applied. Our experimental results prove that by the application of post-growth RPP is possible to essentially improve the crystallinity of the deposited TiO2 films. (authors)

2013-04-18

19

Fabrication of TiO2 thin film memristor device using electrohydrodynamic inkjet printing  

International Nuclear Information System (INIS)

In this paper, we are reporting the fabrication of memristor device (Ag/TiO2/Cu) using electrohydrodynamic inkjet printing technology. The titanium oxide (TiO2) active layer was deposited using electrohydrodynamic atomization technique. The metal electrodes were patterned by using electrohydrodynamic printing technique. The crystalline nature, surface morphology and optical properties of as deposited TiO2 films were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible spectroscopic analysis respectively. XRD and SEM studies revealed that the presence of anatase TiO2 with uniform deposition. The optical transmittance of the deposited TiO2 films was observed to be 87% in the visible region. The fabricated memristor device (Ag/TiO2/Cu) exhibits bipolar resistive switching behavior within the low operating voltage (± 0.7 V). Our results ensure that the printed technology provides breakthrough solution in the electronic memory device fabrication. - Highlights: ? Electrohydrodynamic inkjet technique was used to fabricate memristor device. ? The active layer TiO2 presence in the form of anatase. ? The optical transmittance of the TiO2 films was 87% in the visible region. ? Uniform deposition of TiO2 thin film was achieved. ? The Ag/TiO2/Cu device exhibited a bipolar resistive switching behavior.

2012-05-31

20

Preparation and Photocatalytic Activity of TiO2 Thin Films on Al Alloys  

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Full Text Available Using anodized 6061 aluminum alloy and pure aluminum as the templates, TiO2 thin films were prepared through a liquid deposition method. The TiO2 thin film fabricated on the 6061 aluminum alloy substrates appears as bamboo―like structures with holes, whereas that prepared on anodized pure aluminum substrate has one―dimensional tubular structures. The main reason is that magnesium in aluminum alloy is oxidized to form magnesium oxide which has a lower volume than that of Al2O3. The photocatalytic ability of the TiO2 films prepared on the aluminum alloy is superior to that of the films fabricated on the pure aluminum. TiO2 prepared on aluminum alloy has higher specific surface area due to its bamboo―like structures with holes, leading to better performance in the degradation of methylene blue. The photocatalytic performance of the TiO2 by the degradation of aqueous methylene blue is in accordance with the first kinetic equation. TiO2 films deposited in 0.1 mol/L (NH4) TiF6 solution obtain the best photocatalytic performance at apparent reaction rate of 0.00444/min.

CAI Qian, WANG Jin-Shu, LI Hong-Yi, LIU Shao-Lin, LI Yu-Mei

2012-06-01

 
 
 
 
21

Room temperature ferromagnetism in vacuum-annealed TiO2 thin films  

International Nuclear Information System (INIS)

Thin films of pure TiO2 have been prepared using both spin-coating and sputter-deposition techniques on sapphire and quartz substrates. The structural characteristics of the films have been investigated in detail using Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). When annealed in vacuum, all films demonstrate room temperature ferromagnetism, while the air-annealed samples show much smaller, often negligible, magnetic moments. The magnetization of the vacuum-annealed sputtered samples depends on film thickness, with the volume magnetization decreasing monotonically with increasing thickness. Furthermore, the magnetization per unit area also decreases slightly with increasing film thickness. These results suggest that ferromagnetism in the vacuum-annealed TiO2 films is mediated by surface defects or interfacial effects, but does not arise from stoichiometric crystalline TiO2

2008-03-01

22

Magnetism in spin-coated pristine TiO2 thin films  

International Nuclear Information System (INIS)

Spin coated pristine TiO2 thin films show magnetic behaviors that are similar to those of pulsed laser ablated TiO2 thin films that were reported previously. It seems that in this kind of material, ferromagnetism (FM) is indeed intrinsic, and it can be achieved by various deposition techniques. The fact that oxygen annealing degrades the magnetic moment implies that the observed magnetism is likely due to defects or/and oxygen vacancies. Moreover, thick films that were deposited under the same growth conditions have the magnetic ordering degraded enormously. It is found that as for FM in undoped TiO2 films made by the chemical solution deposition, not only do defects/oxygen vacancies play a role, but also the confinement effects seem to be important

2008-04-28

23

Effects of mineral tourmaline particles on the photocatalytic activity of TiO2 thin films.  

Science.gov (United States)

Titania composite thin films (T/TiO2) containing tourmaline particles were prepared by a sol-gel method, using alkoxide solutions as precursor. The tourmaline particles and thin films were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and so on. The effects of tourmaline on the photocatalytic activity of TiO2 were measured with methyl orange as an objective photodegradation substance. The results showed that the photocatalytic degradation of methyl orange conformed to the first-order kinetic equation and the composite thin films had better photocatalytic activity due to the cooperation of polarity and the far infrared emission of tourmaline. The T/TiO2 thin films including 0.5 wt% tourmaline exhibited better photocatalytic activity when heat-treated at 250 degrees C for 3 h, than pure TiO2 thin films under the ultraviolet irradiation. PMID:18468139

Meng, Junping; Liang, Jinsheng; Ou, Xiuqin; Ding, Yan; Liang, Guangchuan

2008-03-01

24

Characterization and Electrical Properties of TiO2 Thin Films Deposited by Pulsed Laser Deposition  

Science.gov (United States)

Thin film technology is very important in today's high-tech industry. TiO2 is a high-k dielectric material. Problems with thin film deposition arise when the thickness of the thin layers approaches a few hundred nm to less than 100 nm. High quality thin films within these dimensions are difficult to obtain. Issues of adhesion, crystal mismatch, crystal orientation, surface roughness, densification, etc. are problems that need to be addressed if good quality thin films for devices are to be fabricated. These factors have a relation with the thin film technique used. As an example, spin coating technique may be a cheaper technique but may not result in dense and very smooth surfaces. Pulsed LASER deposition (PLD) is a relatively newer method used in thin film fabrication. The advantages of PLD are, capability of very thin films being deposited on different types of substrates (up to monolayers), control of crystal orientation, capability of depositing materials with complex stoichiometry and ease of methodology with high throughput. This has industrial implications as a good method for thin film preparation. This work involves the deposition of TiO2 thin films using different deposition parameters and chamber environments.

Badar, Nurhanna; Kamarulzaman, Norlida

2011-12-01

25

The study of structural and optical properties of TiO2:Tb thin films  

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Full Text Available This work presents the study of the structural and optical properties of TiO2:Tb thin films deposited on Si (100 and SiO2 substrates by magnetron sputtering from metallic Ti-Tb mosaic target. Thin films were studied by means of scanning electron microscopy with energy disperse spectrometer (SEM-EDS, atomic force microscopy (AFM, X-ray diffraction (XRD and the optical transmission method. From SEM-EDS the total amount of Tb concentration was determined. XRD analysis revealed the existence of crystalline TiO2 in the form of anatase and rutile, depending on Tb amount in the examined samples. The optical transmission method has shown that Tb doping shifts the fundamental absorption edge of TiO2 toward the longer wavelength region.

Damian Wojcieszak

2007-01-01

26

Electron beam deposited Nb-doped TiO2 toward nanostructured transparent conductive thin films  

International Nuclear Information System (INIS)

Nb-doped TiO2 (TNO) has been widely explored as an alternative transparent conductor. TNO thin films have been fabricated by various deposition methods, and here we demonstrate fabrication by evaporation of sol–gel synthesized TNO source material. A range of NbxTi1?xO2 (x = 0, 0.03, 0.06, 0.12, 0.24) compositions were synthesized, pressed into pellets, and deposited as thin films via electron beam evaporation. The thin films were characterized for composition by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy and for crystallinity by X-ray diffraction for the different Nb contents explored. Transparency, conductivity, and Haacke transparent conductor figure of merit values are reported for the evaporated TNO films as a function of Nb content, substrate heating temperature, and post deposition annealing conditions. Glancing angle deposition (GLAD) is used to demonstrate nanostructuring of evaporated TNO based on physical shadowing. Nanostructured GLAD TNO films of increased morphological complexity can be produced using this method, and could lead to unique transparent conductor device architectures. - Highlights: ? Nb-doped TiO2 sol–gel materials were electron beam evaporated into thin films. ? Thin film Nb-content was correlated with sol–gel Nb-content. ? Transparency and conductivity were related to substrate temperature and Nb-content. ? Nanopillar Nb-doped TiO2 films were fabricated by glancing angle deposition.

2012-12-15

27

Structural, optical and electrochemical properties of TiO2 thin films grown by APCVD method  

International Nuclear Information System (INIS)

Atmospheric pressure chemical vapor deposition (APCVD) of TiO2 thin films has been achieved onto glass and onto ITO-coated glass substrates, from the reaction of TiCl4 with ethyl acetate (EtOAc). The effect of the synthesis temperature on the optical, structural and electrochemical properties was studied through spectral transmittance, X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) measurements. It was established that the TiO2 films deposited onto glass substrate, at temperatures greater than 400 deg. C grown with rutile type tetragonal structure, whereas the TiO2 films deposited onto ITO-coated glass substrate grown with anatase type structure. EIS was applied as suitable method to determine the charge transfer resistance in the electrolyte/TiO2 interface, typically found in dye-sensitized solar cells.

2010-04-15

28

Effect of Au Nanoparticles Doping on The Properties of TiO2 Thin Films  

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Full Text Available In this study, pure and gold (Au nanoparticles doped TiO2 thin films (Au/Ti = 10, 20, 30, 40 and 50 at% were prepared by sol-gel method and the impact of Au nanoparticles doping on the optical, structural and morphological properties of these thin films was examined. All thin films were characterized using ultraviolet-visible-near infrared (UV-Vis-NIR spectrophotometry, X-ray diffraction (XRD, transmission electron microscopy (TEM and atomic force microscopy (AFM. The optical band gap of the thin films increases from 3.74 eV to 3.89 eV with the increase of Au nanoparticles concentrations due to the Moss-Burstein effect. XRD results show that all thin films have cubic poly-crystal structure and the intensities of peaks of the crystalline phase increased with the increase of Au nanoparticles concentrations. The AFM results indicate that the TiO2 thin ?lms are formed from the nanoparticles and the grain size of the ?lms is changed with Au doping level. Consequently, it is shown that the structural, morphological and optical properties of the TiO2 thin ?lms could be changed by Au nanoparticles-doping. DOI: http://dx.doi.org/10.5755/j01.ms.20.1.3709

Aytaç GÜLTEK?N

2014-02-01

29

Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications  

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TiO2 thin films were synthesized by sol-gel process: titanium tetraisopropoxide (TTIP) was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The as prepared sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 °C (2 h). The morphological properties of the prepared films were analyzed by Scanning Electron Microscopy (SEM) and Atomic F...

Tahar Touam; Lamia Znaidi; Dominique Vrel; Iva Ninova-Kuznetsova; Ovidiu Brinza; Alexis Fischer; Azzedine Boudrioua

2013-01-01

30

Reactive direct current magnetron sputtered TiO2 thin films with amorphous to crystalline structures  

International Nuclear Information System (INIS)

TiO2 thin films were deposited on soda-lime glass substrates by reactive direct current magnetron sputtering in a mixture of pure argon and oxygen. The influence of both the deposition time, td, and the post-annealing treatments on the films morphology, composition and structure was analyzed by scanning electron microscopy, ellipsometry, X-ray photoelectrons spectroscopy, X-ray diffraction (XRD) and Raman spectroscopy. Amorphous TiO2 was obtained for the shortest deposition time, td = 15 min. Increasing td up to 30 min, poorly crystallized anatase and rutile phases were formed together with amorphous TiO2, as was revealed by complementary XRD patterns and Raman spectra. For longer td, the growth of the anatase phase dominates that of the rutile phase. The post-annealing treatment of the films in air at 450 oC. induced the complete crystallization of the films leading to mainly anatase films for all the deposition times. All these results show the feasibility to fabricate stoichiometric TiO2 thin films with amorphous to crystalline structures by means of soft fabrication conditions: low substrate temperature and moderate annealing treatment

2008-07-31

31

Antibacterial and Photodegradative Properties of Metal Doped TiO2 thin Films Under Visible Light.  

Science.gov (United States)

Doped (Au, Ag) and undoped TiO2 thin films were prepared on soda-lime glass via the sol-gel method by dip-coating from TiCl4 precursor, followed by 30 minutes calcination at 500 °C to obtain transparent thin films with good adhesion to the substrate. XRD analysis showed that the particle size of samples heat treated at 500 °C was ~10 nm for all of the samples prepared, both doped and undoped ones. SEM images revealed that the thin film surface was homogeneous and nano-porous. The hydrophilicity of the thin films was estimated by contact angle measurements. The photodegradation rate of an aqueous solution of the azo dye Plasmocorinth B on the thin films was tested by in-situ UV-Vis spectroscopic measurements of the dye solution. The best photocatalytic activity under visible and UVA light was exhibited by undoped TiO2 thin films, whereas Au doped thin films were slightly less active. On the other hand, the best antimicrobial activity toward the E. coli strain DH5a under visible light was displayed by the Au/TiO2 thin films. PMID:24061239

Ogorevc, Jerneja Šauta; Tratar-Pirc, Elizabeta; Matoh, Lev; Peter, Bukovec

2012-06-01

32

Sputter joining of TiO2 / SiO2 thin film system  

International Nuclear Information System (INIS)

Attempt has been made to join TiO2 / SiO2 multilayer thin films at low temperature during sputter deposition. Joining strength was evaluated by haze value after abrasion test. Joining strength was found to be improved by forming Al2O3 layer of 10 nm thickness at the interface between TiO2 and SiO2. Transmission electron microscopic observation revealed the formation of disordered layer at the interfaces of SiO2 / Al2O3 and Al2O3 / TiO2. Results can be explained in terms of the formation of disordered interfacial structures without special heat treatment caused by local heat evolution at growing film surface by the deposition of kinetic energy of sputtered particles.

2011-09-19

33

Optical and hydrophilic properties of nanostructure Cu loaded brookite TiO2 thin film  

International Nuclear Information System (INIS)

Copper loaded TiO2 brookite thin films were deposited on glass substrates using the dip-coating method. The crystalline structure of the films was characterized by X-ray diffraction analysis. X-ray photoelectron spectroscopy was used to evaluate the properties of the film surfaces. The transmittance spectra of the films were obtained by the Shimadzu multi-purpose spectrophotometer. The water contact angle on the film surfaces during irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicate that Cu loading did not affect the transmittance spectra, whereas it had a significant effect on the hydrophilicity of the TiO2 film surface.

2011-11-30

34

Synthesis of photosensitive nanograined TiO2 thin films by SILAR method  

International Nuclear Information System (INIS)

Nanocrystalline TiO2 thin films are deposited by simple successive ionic layer adsorption and reaction (SILAR) method on glass and fluorine-doped tin oxide (FTO)-coated glass substrate from aqueous solution. The as-deposited films are heat treated at 673 K for 2 h in air. The change in structural, morphological and optical properties are studied by means of X-ray diffraction (XRD), selected area electron diffraction (SAED), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and UV-vis-NIR spectrophotometer. The results show that the SILAR method allows the formation of anatase, nanocrystalline, and porous TiO2 thin films. The heat-treated film showed conversion efficiency of 0.047% in photoelectrochemical cell with 1 M NaOH electrolyte.

2009-06-10

35

Natural superhydrophilic TiO2/SiO2 composite thin films deposited by radio frequency magnetron sputtering  

International Nuclear Information System (INIS)

TiO2/SiO2 composite thin films deposited on various substrates have been prepared by radio frequency magnetron sputtering from a composite target. The composite films were characterized by X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy and water contact angel measurements. XRD analysis indicates the amorphous structures of TiO2/SiO2 composite thin films. Contact angle results show that TiO2/SiO2 composite thin films represent natural superhydrophilicity without UV irradiation due to the enhanced acidity at SiO2-TiO2 interfaces. The heat treatment is necessary to promote thermal diffusion of Si4+ or Ti4+ cations within TiO2 or SiO2 hosts. In addition, radio frequency magnetron sputtering also may play a role in the formation of hydrophilic film surfaces.

2009-06-24

36

Electrochemical deposition of silver nanoparticles on TiO 2/FTO thin films  

Science.gov (United States)

Silver nanoparticles were deposited on titanium oxide IV (TiO 2) thin films supported on FTO (fluorine-doped tin oxide IV) glass using a double pulse electrochemical deposition method. A systematic study of particle nucleation and growth is presented as a function of applied potential and time. Samples were analyzed by grazing-angle X-ray diffraction (GIXRD) technique and morphology was observed using Scanning Electron Microscopy and Energy Dispersive Spectroscopy device (SEM-EDS). Our results confirm the possibility of controlled electrochemical homogeneous deposition of metallic silver particles over TiO 2 surface, which exhibit a potential application in catalytic processes.

Dávila-Martínez, Rosa E.; Cueto, Luisa F.; Sánchez, Eduardo M.

2006-09-01

37

Dynamic Adsorption of Albumin on Nanostructured TiO2Thin Films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Spectroscopic ellipsometry was used to characterize the optical properties of thin (<5 nm) films of nanostructured titanium dioxide (TiO2). These films were then used to investigate the dynamic adsorption of bovine serum albumin (BSA, a model protein), as a function of protein concentration, pH, and ionic strength. Experimental results were analyzed by an optical model and revealed that hydrophobic interactions were the main driving force behind the adsorption process, resulting in up to 3.5 ...

Wehmeyer, Jennifer L.; Synowicki, Ron; Bizios, Rena; Garci?a, Carlos D.

2010-01-01

38

Growth and characterization of anatase phase TiO2 thin films deposited by magnetron sputtering  

International Nuclear Information System (INIS)

TiO2 thin films were deposited by DC reactive magnetron sputtering on glass substrate. The effect of various deposition conditions viz. substrate temperature, gas pressure, target to substrate distance on the crystallinity and rutile/anatase phase formation is studied in details and the deposition conditions, are optimized such that good quality crystalline anatase films can be prepared with ease. The characterization by x-ray diffraction, Raman spectroscopy and AFM is described. (author)

2007-12-27

39

TiO2 nanoparticle thin film-coated optical fiber Fabry-Perot sensor.  

Science.gov (United States)

In this paper, a novel TiO(2) nanoparticle thin film coated optical fiber Fabry-Perot (F-P) sensor had been developed for refractive index (RI) sensing by monitoring the shifts of the fringe contrast in the reflectance spectra. Using in situ liquid phase deposition approach, the TiO(2) nanoparticle thin film could be formed on the fiber surface in a controlled fashion. The optical properties of as-prepared F-P sensors were investigated both theoretically and experimentally. The results indicated that the RI sensitivity of F-P sensors could be effectively improved after the deposition of nanoparticle thin-films. It was about 69.38 dB/RIU, which was 2.6 times higher than that of uncoated one. The linear RI measurement range was also extended from 1.333~1.457 to 1.333~1.8423. More importantly, its optical properties exhibited the unique temperature-independent performance. Therefore, owing to these special optical properties, the TiO(2) nanoparticle thin film coated F-P sensors have great potentials in medical diagnostics, food quality testing, environmental monitoring, biohazard detection and homeland security, even at elevated temperature. PMID:23481766

Jiang, Mingshun; Li, Qiu-Shun; Wang, Jun-Nan; Jin, Zhongwei; Sui, Qingmei; Ma, Yaohong; Shi, Jianguo; Zhang, Faye; Jia, Lei; Yao, Wei-Guo; Dong, Wen-Fei

2013-02-11

40

Diffraction-aided laser-induced microstructuring of thin TiO2 films on glass  

International Nuclear Information System (INIS)

Thin films of TiO2 are deposited by magnetron sputtering on glass substrate and are irradiated by ultraviolet radiation using a KrF excimer laser. These thin films are patterned with a razor blade placed in the way of the radiation. When the fluence is in the 1250-1550 mJ/cm2 range, a regular structure appears, with controlled ablation of the films. It is shown that above a critical local fluence, the ablated depth varies linearly with the local fluence. The proportionality factor is shown to be equal to two photons per evaporated molecule

2006-10-16

 
 
 
 
41

Ellipsometric studies on TiO2 thin films synthesized by spray pyrolysis technique  

International Nuclear Information System (INIS)

TiO2 thin films were synthesized on quartz substrates at substrate temperatures of 350 deg. C and 450 deg. C by thermal spray pyrolysis technique using titanium oxy-acetyl acetonate as a precursor. The optical properties of the thin films were characterized by a Spectroscopic Ellipsometer (SE). The surface morphology of the thin films was studied using Atomic Force Microscopy (AFM). The surface roughness values obtained using AFM and SE was compared. The refractive indices of the films were computed using a point by point ellipsometric data extraction procedure. The porosity of the films were modeled from the optical data by effective medium approximation and corroborated from empirical relations. Using Forouhi-Bloomer optical dispersion model, further treatment of SE data was carried out. The experimental investigations and modeling of the data were directed towards optical benchmarking of spray pyrolyzed titania thin films.

2011-06-15

42

Reaction of Ru(II) diazafluorenone compound with nanocrystalline TiO2 thin film.  

Science.gov (United States)

The Ru(II) compounds [Ru(bpy)(2)(mcbH)](2+) and [Ru(bpy)(2)(dafo)](2+), bpy is 2,2'-bipyridine where mcbH is 3-(CO(2)H)-2,2'-bipyridine and dafo is 4,5-diazafluoren-9-one, were synthesized, characterized, and anchored to nanocrystalline mesoporous TiO(2) thin films for excited state and interfacial electron transfer studies. X-ray crystallographic studies of [Ru(bpy)(2)(mcbH)](PF(6))(Cl) revealed a long Ru-N distance to the unsubstituted pyridine ligand of mcbH. Reaction of [Ru(bpy)(2)(dafo)](2+) with TiO(2) thin films resulted in interfacial chemistry. The IR, (1)H NMR, UV-vis, and photoluminescence spectral data indicated a room-temperature ring-opening reaction of the dafo ligand of [Ru(bpy)(2)(dafo)](2+) that ultimately yielded a carboxylate group in the 3-position of bipyridine anchored to TiO(2). Comparative reactions of [Ru(bpy)(2)(mcbH)](2+) with TiO(2) were performed and support this conclusion. In regenerative photoelectrochemical solar cells with 0.5 M LiI/0.05 M I(2) in acetonitrile, photocurrent action spectra were observed for both sensitized materials. The incident photon-to-current efficiency (IPCE) was significantly lower for Ru(bpy)(2)(dafo)/TiO(2), behavior attributed to a lower excited-state injection yield. PMID:20701276

Heuer, William B; Xia, Hai-Long; Abrahamsson, Maria; Zhou, Zhen; Ardo, Shane; Narducci Sarjeant, Amy A; Meyer, Gerald J

2010-09-01

43

S180 cell growth on low ion energy plasma treated TiO2 thin films  

International Nuclear Information System (INIS)

X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (2 thin films deposited by radio frequency (RF) magnetron sputter system. The low energy argon ion plasma surface modification of TiO2 in a two-stage hybrid system had increased the proportion of surface states of TiO2 as Ti3+. The proportion of carbon atoms as alcohol/ether (C-OX) was decreased with increase the RF power and carbon atoms as carbonyl (C=O) functionality had increased for low RF power treatment. The proportion of C(=O)OX functionality at the surface was decreased at low power and further increase in power has showed an increase in its relive proportion at the surface. The growth of S180 cells was observed and it seems that cells are uniformly spreads on tissue culture polystyrene surface and untreated TiO2 surfaces whereas small-localised cell free area can be seen on plasma treated TiO2 surfaces which may be due to decrease in C(=O)OX, increase in C=O and active sites at the surface. A relatively large variation in the surface functionalities with no change in the surface roughness was achieved by different RF plasma treatments of TiO2 surface whereas no significant change in S180 cell growth with different plasma treatments. This may be because cell growth on TiO2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry

2008-03-30

44

Nanocomposite thin film TiO2/CdS electrodes prepared by thermal evaporation process for photovoltaic applications  

International Nuclear Information System (INIS)

The incorporation of cadmium sulfide (CdS) into TiO2 nanoparticle thin films was investigated. The nanoparticle TiO2 thin film onto an indium doped-tin oxide (ITO) substrate was deposited by Electron Beam Deposition (EBD) combined with thermal process. Then a CdS thin film was vacuum-deposited onto the pre-deposited TiO2 film by a thermal evaporation technique. The obtained TiO2/CdS was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). The TiO2/CdS nanocomposite film was used in a photo-electrochemical (PEC) cell as a working electrode and a platinum electrode as a counter electrode. The electrolyte solution contain 1 M KCl and 0.1 M Na2S. The results show that the cell with TiO2/CdS. Composite film electrode has significantly improved photoelectric capability in comparison with that of the pure TiO2 thin films. (author)

2011-03-01

45

Synthesis and characterization of TiO2 thin films coated on metal substrate  

International Nuclear Information System (INIS)

Nanostructured titanium dioxide (TiO2) thin films have been prepared on metal substrates using a facile layer-by-layer dip-coating method. The phase structure and morphologies of preparing samples were characterized by means of X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The results confirm that films are highly crystalline anatase TiO2 and free from other phases of titanium dioxide. Scanning electron microscopy (SEM) shows that the nanoparticles are sintered together to form a compact structure. The electrical properties of samples were investigated by cutternt-voltage analysis, the result indicates that a rectifying junction between the nanocrystalline TiO2 film and metal substrate was formed. The photoelectrochemical characteristics recorded under 1.5 AM illumination indicates that the as-fabricated thin film electrode possesses the highest photocurrent density at 450 deg. C, which is 1.75 mA/cm2 at 0 V vs. Ag/AgCl.

2010-03-01

46

Nanoporous TiO2 thin film based conductometric H2 sensor  

International Nuclear Information System (INIS)

Nanoporous titanium dioxide (TiO2) based conductometric sensors have been fabricated and their sensitivity to hydrogen (H2) gas has been investigated. A filtered cathodic vacuum arc (FCVA) system was used to deposit ultra-smooth Ti thin films on a transducer having patterned inter-digital gold electrodes (IDTs). Nanoporous TiO2 films were obtained by anodization of the titanium (Ti) thin films using a neutral 0.5% (wt) NH4F in ethylene glycol solution at 5 V for 1 h. After anodization, the films were annealed at 600 oC for 8 h to convert the remaining Ti into TiO2. The scanning electron microscopy (SEM) images revealed that the average diameters of the nanopores are in the range of 20 to 25 nm. The sensor was exposed to different concentrations of H2 in synthetic air at operating temperatures between 100 oC and 300 oC. The sensor responded with a highest sensitivity of 1.24 to 1% of H2 gas at 225 oC.

2009-12-15

47

Water effect on the surface morphology of TiO2 thin film modified by polyethylene glycol  

International Nuclear Information System (INIS)

Highlights: ? TiO2 porous thin film is fabricated using polyethylene glycol 6000 (PEG-6000) as a template. ? The water molecules provide locations for the aggregation of PEG-6000, and it is demonstrated by the phase diagrams of AFM. ? The water content has an influence on the surface structure and the thin film thickness. ? The TiO2 thin film has the best photocatalytic activity when the ratio of water to Ti precursor is 2. - Abstract: Water effect on the surface morphology of TiO2 thin film was investigated by using PEG-6000 as a template to form the porous structure. The porous TiO2 thin films were characterized by thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), n and k Analyzer, UV–vis spectrophotometer, field-emission scanning electron microscopy (FE-SEM), and atomic forced microscopy (AFM) as a function of water content in the preparation of TiO2 thin film. The various water contents result in the TiO2 thin films possessing different surface structures, grain sizes, and thicknesses. The grain sizes were varied with changing the water content, and the thickness increased with increasing water content due to the enhancement of the cross-linking speed. In addition, the cratered surface structure transformed into cracked surface structure upon the water content beyond stoichiometric quantity because the excess water causes the aggregation of polyethylene glycol (PEG-6000). The photocatalysis has been performed by the degradation of methyl blue with corresponding structural characteristics of the TiO2 thin film. The best photocatalytic activity has been obtained when the ratio of water to titanium precursor is equal to 2 referred as TiO2-W2.

2013-01-01

48

Nitridation of nanocrystalline TiO2 thin films by treatment with ammonia  

International Nuclear Information System (INIS)

Nanocrystalline anatase (TiO2) thin films prepared by a physical vapour deposition method were nitrided by annealing in flowing NH3 at temperatures ranging between 650 oC and 700 oC. It was established that there was a narrow window of temperatures which allowed both incorporation of interstitial nitrogen into the films with retention of the anatase phase without chemical reduction and preservation of the characteristic nanocrystalline morphology. These optimally modified films responded to visible light in photowetting tests and showed the ability to degrade an organic dye under visible light irradiation.

2011-03-31

49

Self-Cleaning Properties of Vanadium Doped TiO2 Sol-Gel Derived Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, vanadium doped TiO2 thin films were deposited on glass substrates using a sol-gel dip-coating process. X-Ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and UV-Vis spectrophotometer were used to characterize the structural, chemical and the optical properties of the thin films. The photo-catalytic activities of films were investigated by methylene blue degradation. Water contact angle on the film surfaces was measured by a water contact angle analyzer. The results indicated that vanadium doping had a significant effect on the self-cleaning properties of TiO2 thin films.

Mehrnoush Mokhtarimehr

2013-07-01

50

Secondary ion mass spectrometry and X-ray photoelectron spectroscopy studies on TiO 2 and nitrogen doped TiO 2 thin films  

Science.gov (United States)

Anatase phase TiO 2 and nitrogen (N) doped TiO 2 thin films were synthesized by an ultrasonic spray pyrolysis technique on c-Si (100) substrates in the temperature range 300-550 °C. The former used a precursor solution of titanium oxy acetylacetonate in methanol whereas the later used a titanium oxy acetylacetonate hexamine mixture in methanol. Homogeneity across the film's thickness and the nature of the film-substrate interface were studied by dynamic depth profiling acquired using secondary ion mass spectrometry SIMS. The stoichiometry and bonding state of various species present in the films were studied using X-ray photoelectron spectroscopy (XPS). N-doping was confirmed by both SIMS and XPS. XPS studies revealed that the nitrogen content of the films synthesized at 300 °C (3.2%) is high compared to that of films made at 350 °C (1.3%).

Raut, N. C.; Mathews, T.; Rajagopalan, S.; Subba Rao, R. V.; Dash, S.; Tyagi, A. K.

2011-02-01

51

Tio2 Nanoparticles Coated With Porphyrin Dye Thin Film As Fluorescence Gas Sensor  

International Nuclear Information System (INIS)

This research explores the possibility of using fluorescence technique to detect the presence of volatile organic compounds based on a single sensing material. The material used was TiO2 nanoparticles coated with porphyrin dye. The TiO2 nanoparticles colloid is in a sol-gel form synthesized from titanium (IV) ethoxide in ethanol with addition of potassium chloride (KCl) as stabilizer. TiO2 nanoparticles were then coated with porphyrin dye, Manganese (III) 5,10,15,20 tetra (4-pyridyl)-21H, 23H porphine chloride tetrakis (meta chloride). The coated nanoparticles were deposited on quartz substrate using self-assembly through dip coating technique. The sensing properties of the thin film toward volatile organic compounds; ethanol, acetone, cyclohexane and 2-propanol were studied using luminescence spectrometer. It was found that the thin film produced different emission spectra peaks for different volatile organic compounds (VOCs). Hence, it eases chemical identification process and potentially be use as fluorescence gas sensor. (author)

2008-09-01

52

Structural and optical properties of nanocrystalline TiO2 thin films grown by RF magnetron sputtering  

International Nuclear Information System (INIS)

Full text: TiO2 exists in three different polymorphs such as anatase, rutile and brookite. The anatase phase is stable at low temperatures (upto 600 deg C) and rutile structure is stable at high temperatures (700 - 800 deg C). The anatase TiO2 thin films have applications in dye sensitized solar cells (DSSCs) and photocatalysis. TiO2 thin films were prepared using RF magnetron sputtering at room temperature. As prepared thin films were amorphous in nature and ex-situ air and oxygen annealed thin films at 500 deg C for 2 H show anatase crystallinity. The structural and morphological studies of the thin films were performed by X-ray diffraction, Raman spectroscopy and Atomic Force Microscopy (AFM). The optical properties of thin films were studied by UV-Visible spectra. The nanocrystalline TiO2 thin films were transparent in visible region (maximum ?83% for oxygen annealed and 0.03 mbar Ar pressure). The thin films annealed in air show larger crystallite size than oxygen annealed thin films. This was also confirmed by Raman, AFM and band gap calculations. The band gap of the oxygen annealed thin films were greater compared to that of air annealed thin films due to smaller crystallite size. The direct hand gap of thin films were calculated and found to be in the range 3.8 - 3.9 eV. The increase in hand gap as the crystallite size decreases indicates size dependent quantum confinement effect. The nano crystalline TiO2 thin film with such a higher band gap (3.9 eV) will be used as a buffer layer in hybrid DSSCs and also as an anode in DSSCs. Results will be presented in detail

2009-12-09

53

Characterization of sol-gel thin films of TiO2-PbO, TiO2-Bi2O3 and TiO2-CeO2 compositions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Single and multilayer sol-gel thin films of TiO2-PbO, TiO2-Bi2O3 and TiO2-CeO2 composition were deposited on glasses using the dip coating technique. The precursors included Ti(OPr(i))4 chemically modified by acetyl acetone and diluted in Pr(i)OH and sols of Pb(OAc)2, Bi(NO3)3 5H2O diluted in acetic acid. The TiO2-CeO2 sol was prepared by mixing Ce(NH4)2(NO3)6 in ethanol and then adding Ti(O-iso-C3H7)4. Structure texture and homogeneity of their main constituents was established b...

Aegerter, Michel A.; La Serra, Eliane R.; Martins Rodrigues, Ana Candida; Kordas, George; Moore, Glenn

1990-01-01

54

Water effect on the surface morphology of TiO2 thin film modified by polyethylene glycol  

Science.gov (United States)

Water effect on the surface morphology of TiO2 thin film was investigated by using PEG-6000 as a template to form the porous structure. The porous TiO2 thin films were characterized by thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), n&k Analyzer, UV-vis spectrophotometer, field-emission scanning electron microscopy (FE-SEM), and atomic forced microscopy (AFM) as a function of water content in the preparation of TiO2 thin film. The various water contents result in the TiO2 thin films possessing different surface structures, grain sizes, and thicknesses. The grain sizes were varied with changing the water content, and the thickness increased with increasing water content due to the enhancement of the cross-linking speed. In addition, the cratered surface structure transformed into cracked surface structure upon the water content beyond stoichiometric quantity because the excess water causes the aggregation of polyethylene glycol (PEG-6000). The photocatalysis has been performed by the degradation of methyl blue with corresponding structural characteristics of the TiO2 thin film. The best photocatalytic activity has been obtained when the ratio of water to titanium precursor is equal to 2 referred as TiO2-W2.

Wang, Sheng-Hung; Wang, Kuo-Hua; Dai, Yong-Ming; Jehng, Jih-Mirn

2013-01-01

55

TiO2 thin film growth using the MOCVD method  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Titanium oxide (TiO2) thin films were obtained using the MOCVD method. In this report we discuss the properties of a film, produced using a ordinary deposition apparatus, as a function of the deposition time, with constant deposition temperature (90 °C), oxygen flow (7,0 L/min) and substrate tempera [...] ture (400 °C). The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and visible and ultra-violet region spectroscopy (UV-Vis). The films deposited on Si (100) substrates showed the anatase polycrystalline phase, while the films grown on glass substrates showed no crystallinity. Film thickness increased with deposition time as expected, while the transmittance varied from 72 to 91% and the refractive index remained close to 2.6.

Bernardi, M.I.B.; Lee, E.J.H.; Lisboa-Filho, P.N.; Leite, E.R.; Longo, E.; Varela, J.A.

56

TiO2 thin film growth using the MOCVD method  

Directory of Open Access Journals (Sweden)

Full Text Available Titanium oxide (TiO2 thin films were obtained using the MOCVD method. In this report we discuss the properties of a film, produced using a ordinary deposition apparatus, as a function of the deposition time, with constant deposition temperature (90 °C, oxygen flow (7,0 L/min and substrate temperature (400 °C. The films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM and visible and ultra-violet region spectroscopy (UV-Vis. The films deposited on Si (100 substrates showed the anatase polycrystalline phase, while the films grown on glass substrates showed no crystallinity. Film thickness increased with deposition time as expected, while the transmittance varied from 72 to 91% and the refractive index remained close to 2.6.

M.I.B. Bernardi

2001-07-01

57

Preparation of TiO2 thin films from autoclaved sol containing needle-like anatase crystals  

International Nuclear Information System (INIS)

A new inorganic sol-gel method was introduced in this paper to prepare TiO2 thin films. The autoclaved sol with needle-like anatase crystals was synthesized using titanyl sulfate (TiOSO4) and peroxide (H2O2) as starting materials. The transparent anatase TiO2 thin films were prepared on glass slides from the autoclaved sol by sol-gel dip-coating method. A wide range of techniques such as Fourier transform infrared transmission spectra (FT-IR), X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopes, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrum were applied to characterize the autoclaved sol and TiO2 thin films. The results indicate that the autoclaved sol is flavescent, semitransparent and stable at room temperature. The anatase crystals of TiO2 films connect together to form net-like structure after calcined and the films become uniform with increasing heating temperature. The surface of the TiO2 films contain not only Ti and O elements, but also a small amount of N and Na elements diffused from substrates during heat treatment. The TiO2 films are transparent and their maximal light transmittances exceed 80% under visible light region

2006-11-15

58

Photocatalytic antibacterial performance of Sn(4+)-doped TiO(2) thin films on glass substrate.  

Science.gov (United States)

Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect. PMID:18656312

Sayilkan, Funda; Asiltürk, Meltem; Kiraz, Nadir; Burunkaya, Esin; Arpaç, Ertu?rul; Sayilkan, Hikmet

2009-03-15

59

Preparation and Characterization of TiO2-SiO2 Thin Films  

International Nuclear Information System (INIS)

Sol-gel, is a method being used for preperation of thin films for a very long time. Its easy application process with easily available equipments that are used and the low process temperatures are the reasons for being utilized this much. A very common thin film type, TiO2-SiO2, that has been used in optical applications for a long time, is the basic structure involved in this research. In this work, the titania (TiO2) and the silica (SiO2) solutions which had been preperated seperately, were mixed with different ratios, and the differences between these mixtures that might had been occurred were investigated. The glass substrates, which had been cleaned with a special method were dipped into the mixed solutions with a constant speed which they had exactly the same while they were being withdrawned. After being dried in mid-air for a while, they were heated to 150 degree and then were dipped again. Once the number of the layers that was required is reached with reprocesses, the substrates were heated to 600 degree. The optical and the structural properties of the films deposited on the substrates were investigated. Some differences in optical properties of these films that were produced from different ratios of solutions were observed as result

2008-08-25

60

Effect of rapid thermal annealing on nanocrystalline TiO2 thin films synthesized by swift heavy ion irradiation  

International Nuclear Information System (INIS)

Irradiation by swift heavy ions (SHI) is unique tool to synthesize nanocrystalline thin films. We have reported transformation of 100 nm thick amorphous films into nanocrystalline film due to irradiation by 100 MeV Ag ion beam. Oblate shaped nanoparticles having anatase phase of TiO2 were formed on the surface of the irradiated films. In the present investigation, these films are annealed at 350 °C for 2 min in oxygen atmosphere by Rapid Thermal Annealing (RTA) method. During RTA processing, the temperature rises abruptly and this thermal instability is expected to alter surface morphology, structural and optical properties of nanocrystalline TiO2 thin films. Thus in the present work, effect of RTA on SHI induced nanocrystalline thin films of TiO2 is studied. The effect of RTA processing on the shape and size of TiO2 nanoparticles is studied by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Glancing Angle X-ray Diffraction (GAXRD) studies are carried to investigate structural changes induced by RTA processing. Optical characterization is carried out by UV-vis spectroscopy and photoluminescence (PL) spectroscopy. The changes observed in structural and optical properties of nanocrystalline TiO2 thin films after RTA processing are attributed to the annihilation of SHI induced defects.

2012-08-01

 
 
 
 
61

Radiation effects studies on thin film TiO2 memristor devices  

Science.gov (United States)

Memristor devices have been identified as potential replacements for a variety of memory applications and may also be suitable for space applications. In this work, we present a review of radiation testing on TiO2-based memristor devices. The experimental results from three previous studies are reviewed and coupled here with modeling to gain a more complete understanding of the energy deposition and resulting effects on the electrical performance of the device. In addition, we discuss the implications of having a nanometer scaled thin film device and how that affects the energy deposition from the various radiation sources.

DeIonno, Erica; Looper, Mark D.; Osborn, Jon V.; Barnaby, Hugh J.; Tong, William M.

62

Multilevel unipolar resistance switching in TiO2 thin films  

Science.gov (United States)

We report on multilevel switching behavior in the unipolar resistance switching of TiO2 thin films. Multiple metastable states were observed during the reset process by measuring I-V curves. As observed using a conducting atomic force microscope, the multilevel resistance switching was accompanied by decreases in area and in the conductance of the top surface conducting regions. These experimental observations at both the macroscopic and microscopic levels could be explained by using the ``random circuit breaker network'' model, which is a dynamic bond percolation model.

Chae, S. C.; Lee, J. S.; Choi, W. S.; Lee, S. B.; Chang, S. H.; Shin, H.; Kahng, B.; Noh, T. W.

2009-08-01

63

Characterization of structure and distortion in the manganese ions implanted TiO2 thin films  

International Nuclear Information System (INIS)

TiO2 thin films were prepared by direct current magnetron sputtering on glass substrates, and then implanted by manganese ions, and finally annealed at different temperatures. They are identified as an anatase structure by XRD, and crystallization of the films is better and better as the annealing temperature increases. SEM images are shown that the grain size of the films will grow big and big with annealing temperature increasing. The EDX measurement indicated that the concentration of manganese was about 4.68%. The HRTEM was used to analyze the fine anatase structure of the Mn-TiO2 composite film, and edge dislocations were further found in the HRTEM image, which could be attributed to the manganese ions implantation effect.

2009-09-15

64

Dry Etching Properties of TiO2 Thin Film Using Inductively Coupled Plasma for Resistive Random Access Memory Application  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, we investigated to the etching characteristics of TiO2 thin film and the selectivity using the inductivelycoupled plasma system. The etch rate and the selectivity were obtained with various gas mixing ratios. The maximumetch rate of TiO2 thin film was 61.6 nm/min. The selectivity of TiO2 to TiN, and TiO2 to SiO2 were obtained as 2.13 and1.39, respectively. The etching process conditions are 400 W for RF power, -150 V for DC-bias voltage, 2 Pa for theprocess pressure, and 40? for substrate temperature. The chemical states of the etched surfaces were investigatedwith X-ray photoelectron spectroscopy (XPS. Its analysis showed that the etching mechanism was based on thephysical and chemical pathways in the ion-assisted physical reaction.

Young-Hee Joo

2012-06-01

65

Photocatalytic activities of TiO2 thin films prepared on Galvanized Iron substrate by plasma-enhanced atomic layer deposition  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films were prepared on Galvanized Iron (GI) substrate by plasma-enhanced atomic layer deposition (PE-ALD) using tetrakis-dimethylamido titanium and O2 plasma to investigate the photocatalytic activities. The PE-ALD TiO2 thin films exhibited relatively high growth rate and the crystal structures of TiO2 thin films depended on the growth temperatures. TiO2 thin films deposited at 200 oC have amorphous phase, whereas those with anatase phase and bandgap energy about 3.2 eV were deposited at growth temperature of 250 oC and 300 oC. From contact angles measurement of water droplet, TiO2 thin films with anatase phase and ActivTM glass exhibited superhydrophilic surfaces after UV light exposure. And from photo-induced degradation test of organic solution, anatase TiO2 thin films and ActivTM glass decomposed organic solution under UV illumination. The anatase TiO2 thin film on GI substrate showed higher photocatalytic efficiency than ActivTM glass after 5 h UV light exposure. Thus, we suggest that the anatase phase in TiO2 thin film contributes to both superhydrophilicity and photocatalytic decomposition of 4-chlorophenol solution and anatase TiO2 thin films are suitable for self-cleaning applications.

2010-06-30

66

Sol-Gel TiO2 thin films sensitized with the mulberry pigment cyanidin  

Digital Repository Infrastructure Vision for European Research (DRIVER)

TiO2 films have various applications, among them solar cells and photodegradation of pollutants. In this study, we investigated TiO2 films functionalized with the organic dye cyanidin extracted from black mulberry (Morus nigra). The TiO2 was functionalized by the sol-gel method and the film was deposited on glass substrates by dip-coating. Our aim was to investigate the interaction between the semiconductor and the dye, as well as the influence of the velocity and number of deposits on the ch...

Emerson Henrique de Faria; Alex Lemes Marçal; Eduardo José Nassar; Katia Jorge Ciuffi; Paulo Sergio Calefi

2007-01-01

67

Structural and morphological characterization of TiO2 thin films synthesized by spray pyrolysis technique.  

Science.gov (United States)

Thin films of nanocrystalline TiO2 were synthesized by spray pyrolysis technique in the temperature range 300 degrees C to 550 degrees C in steps of 50 degrees C. The films were coated on glass and quartz substrates by ultrasonic nebulization of titanium-oxy-acetyl acetonate followed by pyrolysis. The structure and morphology of the thin films were characterized by X-ray Diffraction (XRD), Raman Spectroscopy (RS) and Scanning Electron Microscopy (SEM), while the optical band gaps were measured by Spectroscopic Ellipsometry (SE) and UV-Visible spectroscopy. XRD investigations revealed distinct crystal structures of the films synthesized above and below 300 degrees C. While films grown at substrate temperature 300 degrees C were amorphous, those grown at 350 dgrees C and above showed tetragonal anatase crystal structure. The morphological investigations from SEM showed that the films deposited at 350 degrees C were porous and exhibited flower like morphology. The microstructures of the films grown on quartz at 450 degrees C were found to be uniform and dense. The nominal grain sizes evaluated from High Resolution SEM (HRSEM) studies were approximately 20 nm and compared well with the grain sizes calculated from XRD. The band gap values calculated from ellipsometry studies were approximately 3.7 eV and 3.95 eV for the films grown at 450 degrees C and 350 degrees C, respectively. This is in good agreement with those obtained from UV-Visible spectroscopy. PMID:19928217

Raut, N C; Mathews, Tom; Sundari, S Tripura; Sairam, T N; Dash, S; Tyagi, A K

2009-09-01

68

Titanium dioxide (TIO2) thin film and plasma properties in RF magnetron sputtering  

International Nuclear Information System (INIS)

Lately, titanium dioxide (TiO2) films with anatase crystalline property received numerous attentions as unique material properties. There are wide applications of TiO2 thin film such as for photocatalytic application in solar cell. In the present study, radio frequency (RF) magnetron sputtering technique has been used to produce high dense, homogeneously controllable film layer at low deposition temperature using titanium (Ti) target. The diameter of the Ti target is 3 inch with fixed discharge power of 400W. Magnetron sputtering plasma has been produced in high purity 99.99% Argon (Ar) and 99.99% Oxygen (O2) environment pressure ranging from 5 to 20 mTorr. The TiO2 were growth on silicon and glass substrates. Substrate temperature during deposition was kept constant at 400°C. The distance between target and substrate holder was maintain at 14 cm with rotation of 10 rotation-per-minutes. Our X-ray diffraction result, shows anatase crystalline successfully formed with characterization peaks of plane (101) at 2? = 25.28°, plane (202) at 2? = 48.05° and plane (211) at 2? = 55.06°. In addition, it is our interest to study the plasma properties and optical spectrum of Ti, Ti+ , O- , ArM and Ar+ in the chamber during the deposition process. Result of emission line intensities, electron density and temperature from optical spectroscope and Langmuir probe will be discuss further during the workshop. This works were supported by Graduate Incentive Scheme of Universiti Tun Hussein Onn Malaysia (UTHM) and Fundamental Research Grant Scheme of Ministry of Higher Education, Malaysia. (author)

2013-07-01

69

Structural characterisation of sprayed TiO2 films for extremely thin absorber layer solar cells  

International Nuclear Information System (INIS)

We have examined in detail the structural features of TiO2 films fabricated by spray pyrolysis. The spray solution was produced from the dissolution of Ti powder in a hydrogen peroxide and ammonium hydroxide solution. The resulting peroxo-polytitanic acid solution was diluted in water and sprayed onto heated substrates through an air-atomizing nozzle. Each sample was characterised principally by X-ray powder diffraction and scanning electron microscopy. The effect of spray solution composition and rate has been studied and a brief comparison to films produced by an alternative route ('doctor blade') provided. The films were shown to consist of almost single phase anatase and to be porous. It has been demonstrated that the growth process was uniform although the degree of preferred orientation could be controlled through the concentration of the spray solution. The lattice parameters are both shown to increase slightly with concentration and volume of solution deposited. Semi-quantitative microstructural analyses showed that the crystallites formed are consistently larger than those formed by the doctor blade process although they contain significantly more microstrain. Further, it is demonstrated that thin window layers of copper indium disulfide, also formed by spray pyrolysis, have a conformal relationship with the TiO2

2004-11-01

70

Power-law photoconductivity time decay in nanocrystalline TiO2 thin films  

International Nuclear Information System (INIS)

The sub-band-gap excited photoconductivity (PC) time decay and the film structure of rf-sputter deposited nanocrystalline TiO2 thin films have been studied. Atomic force microscopy and x-ray diffraction measurements were used to assess roughness, crystalline structure and mean grain size of the films. Samples fabricated under different deposition conditions exhibit different microstructures and absolute PC, but similar persistent PC behaviour after switching off the light source. The very slow PC decay can be well represented by a function that is nearly constant for short times and decreases as a power law for times longer than about 100 s. This function is shown to be consistent with a rate equation characterized by a relaxation time that increases linearly with time. This behaviour, in turn, agrees with predictions of a previously reported model that assumes electron-hole recombination limited by carrier-density-dependent potential barriers associated with inhomogeneities. These results may have important implications on attempts to determine distributions of trap energies from PC decay curves in TiO2

2007-12-05

71

The hybrid photocatalyst of TiO2-SiO2 thin film prepared from rice husk silica  

Science.gov (United States)

The TiO2-SiO2 thin film was prepared by self-assembly method by mixing SiO2 precursor with titanium precursor solution and aged to obtain a co-precipitation of silica and titanium crystals. Dip coating method was applied for thin film preparation on glass slide. The X-ray diffraction (XRD) of the self-assembly thin film had no characteristic property of SiO2 and even anatase TiO2 but indicated new crystal structure which was determined from the Fourier Transform Infrared Spectrophotometer (FTIR) as a hybridized Ti-O-Si bonding. The surface area and surface volume of the self-assembly sample were increased when SiO2 was incorporated into the film. The self-assembly TiO2-SiO2 thin film exhibited the enhanced photocatalytic decolorization of methylene blue (MB) dye. The advantages of SiO2 are; (1) to increase the adsorbability of the film and (2) to provide the hydroxyl radical to promote the photocatalytic reaction. The self-assembly thin film with the optimum molar ratio (SiO2:TiO2) as 20:80 gave the best performance for photocatalytic decolorization of MB dye with the overall efficiency of 81%.

Klankaw, P.; Chawengkijwanich, C.; Grisdanurak, N.; Chiarakorn, Siriluk

2012-03-01

72

Characterization of TiO2 thin films prepared by electrolytic deposition for lithium ion battery anodes  

International Nuclear Information System (INIS)

The electrolytic deposition of TiO2 thin films on platinum for lithium batteries is carried out in TiCl4 alcoholic solution and the films are subsequently annealed. The as-prepared films are amorphous TiO(OH)2·H2O, transformed into anatase TiO2 at 350 °C, and then gradually into rutile TiO2 at 500 °C. Cyclic voltammograms show oxidation and reduction peaks at 2.20 and 1.61 V, respectively, corresponding to charge and discharge plateaus at 1.98 and 1.75 V vs. Li+/Li. The specific capacity decreases with increasing current density for film of 128-nm thickness in the initial discharge. It is observed that the diffusion flux of Li+ insertion/extraction into/from TiO2 controls the reaction rate at higher current densities. Consequently, at low film thickness, high discharge capacity (per weight) is found for the initial cycle at a current density of 10 ?A cm?2. However, the capacity of prepared films in various thicknesses approach 103 ± 5 mAh g?1 after 50 cycles, since the formation of cracks for thicker films offers shorter diffusion paths for Li+. In addition, TiO2 films show electrochromic properties during lithiation and delithiation. - Highlights: ? TiO2 films have been prepared by electrolytic deposition for Li ion batteries. ? The capacity decreased with increasing film thickness at higher current density. ? TiO2 films showed electrochromic properties during lithiation and delithiation.

2012-09-01

73

Metal-ion doped p-type TiO2 thin films and their applications for heterojunction devices  

International Nuclear Information System (INIS)

Highlights: ? Solution processed Al+3, Cr+3 and Ni+2 doped TiO2 thin films display p-type conductivity. ? The p-type conductivity was examined through X-ray photoelectron spectroscopy and current–voltage responses. ? The doped thin films were employed as active components in field effect transistor (FET) devices. -- Abstract: Our study revealed that wet chemically processed metal-ion (i.e., Al+3, Cr+3, Ni+2) doped TiO2 thin films could convert its conducting nature from n-type to extrinsic p-type. X-ray photoelectron spectroscopy (XPS) showed shifting of valence band edges with increasing doping concentration. The metal-ion doped TiO2 films were employed as active component in bipolar heterojunction devices, which recorded low turn-on voltage and showed rectification behavior. These results were analyzed to conclude that the doped TiO2 is p-type in nature. Temperature-dependent responses of field effect transistors (FETs) with the p-TiO2 films as channel component revealed efficient features. Conclusive results revealed that reliable and reproducible p-type conductivity could be obtained with Ni+2 doped TiO2

2013-03-15

74

Nano-scaled photocatalytic TiO2 thin films prepared by magnetron sputtering  

International Nuclear Information System (INIS)

The results obtained on the photo-catalytic TiO2 films deposited by reactive magnetron sputtering on unheated substrate in a wide range of the deposition parameters, such as the total pressure, the oxygen partial pressure and the target power will be presented. The correlation between the structure, composition, surface morphology and resulting photo-catalytic properties of nano-scaled TiO2 films is defined. The photo-catalytic behavior is characterized by the measurement of the decomposition of methylene blue and the reduction of the contact angle between water and the TiO2 surface. (Authors)

2002-09-01

75

Preparation and characterization of thin films of TiO2PbO and TiO2Bi2O3 compositions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Single and multilayer thin films of PbTiO3, PbTi4O9 and TiO2Bi2O3 compositions have been prepared on glass and amorphous silica substrates by using the dip-coating technique. After drying and densification, these films have a high optical quality. They have been characterized by the optical transmission technique and XPS. For certain values of their thickness they present almost flat transmission characteristics in the visible range and can be used as achromatic beam splitter or neutral-color...

La Serra, Eliane R.; Charbouillot, Y.; Baudry, Paul; Aegerter, Michel A.

1990-01-01

76

Effect Of Annealing On Structure, Morphology, Electrical And Optical Properties Of Nanocrystalline TiO2 Thin Films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Semi-transparent and highly conducting nanostructured titanium oxide thin films have been prepared by sol-gel method. Thin films of TiO2 deposited on glass substrates using spin coating technique and the effect of annealing temperature (400 - 700 °C) on structural, microstructural, electrical and optical properties were studied. The X-ray diffraction and Atomic force microscopy measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and ru...

Pawar, S. G.; Chougule, M. A.; Godse, P. R.; Jundale, D. M.; Pawar, S. A.; Raut, B. T.; Patil, V. B.

2011-01-01

77

X-ray absorption and emission spectroscopy of TiO2 thin films with modified anionic sublattice  

Science.gov (United States)

Crystallographic and optical properties as well as electronic structure of titanium dioxide thin films with modified anionic sublattice, i.e., non-stoichiometric, undoped and nitrogen doped thin films of TiO2-x and TiO2-x:N, were studied by means of X-ray diffraction, optical spectrophotometry, X-ray absorption and emission spectroscopy. We demonstrate that TiO2-x films undergo a gradual evolution of the crystallographic structure accompanied by the progressive change in interatomic distances with the preserved local symmetry and nearly unchanged effective 3d charge of Ti ions. At a certain degree of oxygen deficit an abrupt change in all the properties studied can be seen. Amorphisation, possible Ti precipitation and increased optical absorption over the visible range correlates well with a significantly higher 3d band occupancy derived from XES for TiO2-x. Thin films of TiO2-x:N demonstrate gradual evolution of the local structure and charge redistribution upon increased level of nitrogen doping.

Kollbek, K.; Sikora, M.; Kapusta, Cz.; Szlachetko, J.; Brudnik, A.; Kusior, E.; Zakrzewska, K.; Radecka, M.

2013-12-01

78

Optimization of TiO2 Thin Film Growth at Different Temperatures by Atomic Layer Deposition  

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In this work TiO2 films were grown on silicon substrates by atomic layer deposition (ALD) using TiCl4 and H2O as precursors. The effect of precursor pulse length and reaction temperature on the film growth rate and film uniformity was studied. The film thickness and refractive indices were measured by ellipsometry.

2011-01-01

79

Synthesis and characterisations of Au-nanoparticle-doped TiO2 and CdO thin films  

Science.gov (United States)

In the present study, pure and gold nanoparticle (Au NP)-doped titanium dioxide (TiO2) and cadmium oxide (CdO) thin film were prepared by the sol–gel method, and the effect of Au NP doping on the optical, structural and morphological properties of these thin films was investigated. The prepared thin films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet–visible–near infrared (UV–Vis–NIR) spectra. While the optical band increases from 3.62 to 3.73 for TiO2 thin films, it decreases from 2.20 to 1.55 for CdO thin films with increasing Au doping concentration. Analysis of XRD indicates that the intensities of peaks of the crystalline phase have increased with the increasing Au NP concentrations in all thin films. SEM images demonstrate that the surface morphologies of the samples were affected by the incorporation of Au NPs. Consequently, the most significant results of the present study are that the Au NPs can be used to modify the optical, structural and morphological properties of TiO2 and CdO thin films.

Gültekin, Aytaç; Karanfil, Gamze; Özel, Faruk; Ku?, Mahmut; Say, Ridvan; Sönmezo?lu, Sava?

2014-06-01

80

Study on the Resistive Switching Behaviors of TiO2 Thin Films by Pulsed Laser Deposition  

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Full Text Available The TiO2 thin films with resistive switching behaviors were grown on Pt (111/Ti/SiO2/Si substrates by pulsed laser deposition (PLD. Scanning electrical microscope (SEM and atomic force microscope (AFM were employed to characterize the as-grown films respectively. No evident diffraction peak of TiO2 is found in X-ray diffraction (XRD pattern. The films exhibit nanocrystalline or noncrystalline. The results show that the surfaces of the films are flat, smooth and dense. The results of electrical test indicate that TiO2 thin films show a unipolar resistive switching behavior, and the high-resistance to low-resistance ratio can reach 104. The electrical conduction of the films at high resistance state is controlled by the space charge limited current mechanism, and the soft-set phenomenon is found. The formation and rupture of conducting filaments in TiO2 thin films are preliminarily analyzed.ª¤

CAO Xun,LI Xiao-Min,YU Wei-Dong,ZHANG Yi-Wen

2009-01-01

 
 
 
 
81

Relationship between scaling behavior and porosity of plasma-deposited TiO2 thin films  

Science.gov (United States)

The growth of TiO2 thin films prepared by plasma enhanced chemical vapor deposition has been studied by analyzing their roughness with the concepts of the dynamic scaling theory. Differences in the growth and roughness exponents have been found depending on the composition of the plasma by using either O2 or mixtures Ar+O2 as plasma gas and titanium isopropoxide as the precursor. The slope of the representations of the film roughness against the deposition time yielded values of the exponent ? of 0.45 and 0.32 for, respectively, thin films prepared with plasmas of O2 or mixtures Ar+O2 . Meanwhile, values of the exponent ? of 1.15 and 1.89/0.35 were deduced from the power spectral density representations for the films prepared under these two experimental conditions. These values are congruent with growth processes dominated, respectively, by shadowing or diffusion processes. A columnar microstructure was observed by scanning electron microscopy for the thin films prepared with pure oxygen. Meanwhile, homogeneous films were obtained with mixtures of Ar+O2 . The open porosity of the films was determined by measuring water adsorption-desorption isotherms with a quartz crystal monitor. This analysis showed that in the samples prepared with mixtures of Ar+O2 the porosity consisted exclusively of micropores (dmeso-pores (d>2nm) . It is concluded that the different growth mechanisms found by just changing the chemistry of the plasma are responsible for the quite distinct microstructures, porosities, and optical properties obtained for the films.

Borrás, A.; Yanguas-Gil, A.; Barranco, A.; Cotrino, J.; González-Elipe, A. R.

2007-12-01

82

Preparation of cross sections of TiO2 thin films for TEM by ultramicrotomy  

International Nuclear Information System (INIS)

Full text: Considerable research is being carried out on dye-sensitised solar cells, the most extensively studied of which are based on a nanostructured titania semiconducting film deposited on a conducting glass substrate. The preparation of cross-sections of these films is essential for investigating of the shape, size and distribution of the TiO2 particles by TEM. In the present work, we have used a relatively simple and rapid procedure involving ultramicrotomy to prepare cross-sections of the films for initial TEM examination. Titania thin films were produced by screen-printing a nanoparticle titania paste onto SnO2-coated glass substrates, followed by heating in air at 500 deg C for 1 hour. The nanoporous films are optically transparent, have a high surface area, and are 7 to 8 ?m thick. The thickness could be checked with a confocal laser scanning microscope using x-z scans in reflection mode. The method for preparing cross-sections was adapted from one used with tissue culture cells on substrates, and which has also been employed with clay minerals. A BEEM capsule half filled with embedding resin was inverted over the glass substrate and TiO2 film, so that the resin was in contact with the film. After polymerisation at 60 deg C overnight, the block was pried away from the glass using a single edged razor blade, leaving the titania film in the resin. The final height of block was about 4-5 mm, and could be directly fitted into an ultramicrotome chuck for sectioning without requiring re-embedding. Ultrathin 60-80 nm sections were cut with a diamond knife, collected on 200 mesh copper grids, then coated with carbon to stabilise the unsupported resin. The sections were examined at 200kV in a Philips CM200 TEM. It was found that the film had detached fully from the glass. The TiO2 grains were observed as mixtures of tetrahedral and rhombohedral geometries with a size distribution in the range 10-25 nm. Anatase and brookite phases present could be identified by electron diffraction. A Ru-containing dye was incorporated in some films, and energy-dispersive X-ray microanalysis was then used to assess the distribution of dye in the cross-sections. Cross-section preparation by the more conventional method of ion-beam thinning can produce thinner specimens and allows the interface between the film and substrate to be studied, but the procedure is more time-consuming. However ultramicrotomy can be a useful complementary technique for relatively rapid TEM examination of thin film cross-sections. Copyright (2002) Australian Society for Electron Microscopy Inc

2002-02-01

83

LETTER TO THE EDITOR: Photoluminescence of anatase TiO2 thin films achieved by the addition of ZnFe2O4  

Science.gov (United States)

We report on the photoluminescence (PL) of anatase TiO2 thin films caused by the addition of ZnFe2O4 nanoparticles prepared by the radio-frequency sputtering method. X-ray diffraction and PL analyses illustrate that there is a very strong band of PL from the anatase TiO2 thin films caused by the addition of ZnFe2O4 at both room and low temperatures; the anatase TiO2 thin films without this addition show no PL. There is a very weak band of PL from rutile TiO2 thin films. The strong PL band for the anatase TiO2 thin films with the addition of ZnFe2O4 may be due to increased localization of impurity- and defect-trapped excitons.

Jin, Yunxia; Li, Guanghai; Zhang, Yong; Zhang, Yunxia; Zhang, Lide

2001-11-01

84

Formation of TiO2 domains in Poly (9-vinylcarbazole) thin film by hydrolysis-condensation of a metal alkoxide  

International Nuclear Information System (INIS)

New organic-inorganic hybrid thin films based on Poly (9-vinylcarbazole) (P9VK) and Dioxide titanium (TiO2) bulk-heterojunction were obtained by a hydrolysis-condensation (H-C) process of titanium (IV) isopropoxide in thin film. The TiO2 distribution in the film was investigated by scanning electron microscopy. The results indicated that homogeneous TiO2 particles around 100 nm were formed on the surface of the polymer thin film. Photoluminescence spectroscopy has been used to study the charge transfer efficiency in the photoactive layer and results were compared with a simplest elaboration route, the dispersion of TiO2 anatase in a P9VK solution before spin coating. Results showed that TiO2 elaborated by H-C exhibits a competitive quenching effect with TiO2 anatase

2007-06-04

85

The properties of metal contacts on TiO2 thin films produced by reactive magnetron sputtering  

Directory of Open Access Journals (Sweden)

Full Text Available The article deals with research on volt-ampere characteristics of metal contacts (Al, Cr, In, Mo, Ti on titanium dioxide thin films and influence of annealing in vacuum on their electric properties. Volt-ampere characteristics measurements were taken by three-probe method. There was established that indium contact on TiO2 thin films possessed sharply defined ohmic properties.

Brus V. V.

2010-10-01

86

Characterization and photocatalytic activity of boron-doped TiO2 thin films prepared by liquid phase deposition technique  

International Nuclear Information System (INIS)

Boron doped TiO2 thin films have been successfully deposited on glass substrate and silicon wafer at 30 deg C from an aqueous solution of ammonium hexa-fluoro titanate and boron trifluoride by liquid phase deposition technique. The boric acid was used as an F scavenger. The resultant films were characterized by XRD, EDAX, UV and microstructures by SEM. The result shows the deposited film to be amorphous which becomes crystalline between 400 and 500 deg C. The EDAX and XRD data confirm the existence of boron atom in TiO2 matrix and a small peak corresponding to rutile phase was also found. Boron doped TiO2 thin films can be used as photocatalyst for the photodegradation of chlorobenzene which is a great environmental hazard. It was found that chlorobenzene undergoes degradation efficiently in presence of boron doped TiO2 thin films by exposing its aqueous solution to visible light. The photocatalytic activity increases with increase in the concentration of boron. (author)

2008-10-01

87

Polythiophene thin films electrochemically deposited on sol-gel based TiO2 for photovoltaic applications  

International Nuclear Information System (INIS)

In this work, the influence of titanium dioxide (TiO2) thin films on the efficiency of organic photovoltaic devices based on electrochemically synthesized polythiophene (PT) was investigated. TiO2 films were produced by sol-gel methods with controlled thickness. The best TiO2 annealing condition was determined through the investigation of the temperature influence on the electron charge mobility and resistivity in a range between 723 K and 923 K. The PT films were produced by chronoamperometric method in a 3-electrode cell under a controlled atmosphere. High quality PT films were produced onto 40 nm thick TiO2 layer previously deposited onto fluorine doped tin oxide (FTO) substrate. The morphology of PT films grown on both substrates and its strong influence on the device performance and PT minimum thickness were also investigated. The maximum external quantum efficiency (IPCE) reached was 9% under monochromatic irradiation (? = 610 nm; 1 W/m2) that is three orders of magnitude higher than that presented by PT-homolayer devices with similar PT thickness. In addition, the open-circuit voltage (Voc) was about 700 mV and the short-circuit current density (Jsc) was 0.03 A/m2 (? = 610 nm; 7 W/m2). However, as for the PT-homolayer also the TiO2/PT based devices are characterized by antibatic response when illuminated through FTO. Finally, the Fill Factor (FF) of these devices is low (25%), indicating that the series resistance (Rs), which is strongly dependent of the PT thickness, is too large. This large Rs value is compensated by TiO2/PT interface morphology and by FTO/TiO2 and TiO2/PT interface phenomena producing preferential paths in which the internal electrical field is higher, improving the device efficiency.

2010-12-30

88

The role of TiO2 addition in ZnO nanocrystalline thin films: Variation of photoelectrochemical responsivity  

International Nuclear Information System (INIS)

Highlights: ? (TiO2)x-(ZnO)1-x systems with different x values were synthesized by sol-gel method. ? XRD showed a decrease in crystallinity of the systems by increasing x value. ? AFM analysis revealed the highest roughness and surface area for the system with x = 10%. ? This system showed highest photoresponse for water splitting and electrical resistance. - Abstract: In this study, the effects of TiO2 addition on the physical and photoelectrochemical properties of ZnO thin films have been investigated. The (TiO2)x-(ZnO)1-x nanocomposite thin films were dip-coated on both glass and indium tin oxide (ITO)-coated conducting glass substrates with various values of x, specifically 0, 0.05, 0.1, 0.25 and 0.5. Optical properties of the samples were studied by UV-vis spectrophotometry in the range of 300-1100 nm. The optical spectra of the nanocomposite thin films showed high transparency in the visible region. The optical bandgap energy of the (TiO2)x-(ZnO)1-x films increased slightly with increasing values of x. The crystalline structure of the nanocomposite films was investigated by X-ray diffraction, which indicated the formation of ZnO nanocrystals in the thin films with x 2 on the surfaces of the films. The photoelectrochemical properties of the samples were also characterized using a high-pressure xenon light source and KOH electrolyte. The addition of 10 mol% (x = 0.1) TiO2 to the ZnO thin films resulted in the best photoresponse in the visible region of the solar spectrum. In addition, the effect of TiO2 concentration on the electrical properties and the flat-band potential of the (TiO2)x-(ZnO)1-x system was studied by impedance spectroscopy; x = 0.1 exhibited the highest donor density and charge-transfer resistance.

2011-07-15

89

Structural and optical properties of TiO2 thin films grown by sol-gel dip coating process  

Science.gov (United States)

The mono and bi-layer TiO2 thin films have been prepared by sol-gel method on glass. X-Ray diffraction, Raman spectroscopy, atomic force microscopy, spectroscopic ellipsometry and m-lines spectroscopy techniques have been used to characterize the TiO2 films. The mono-layer film is found to be amorphous, while the bi-layer film shows the presence of anatase phase. The bi-layer film exhibits more homogeneous surface with less roughness. The thickness effect on the refractive index, extinction ceofficient, packing density and optical band gap is analysed. The waveguiding measurements of the bi-layer film exhibit single-guided TE0 and TM0 polarized modes from which we can measure the refractive index and the film thickness.

Bouachiba, Y.; Bouabellou, A.; Hanini, F.; Kermiche, F.; Taabouche, A.; Boukheddaden, K.

2014-01-01

90

Room temperature synthesis of compact TiO2 thin films for 3-D solar cells by chemical arrested route  

International Nuclear Information System (INIS)

Essential requirement of compact TiO2 thin films for 3-D solar cells prefers high temperature techniques (?400 deg. C) such as spray pyrolysis or sputtering. Under optimized preparative conditions, compact, uniform, adherent and pinhole free, TiO2 thin films were synthesized at room temperature by using arrested precipitation technique on ITO substrates. As-deposited and heat-treated TiO2 films were amorphous with small enlargement in grain size as evidenced from XRD and SEM studies. Small blue shift was detected due to annealing and attributed to change in grain size. As deposited and heat-treated TiO2 films were used in this study showed water contact angles 66.14 deg. and 66.44 deg., respectively. Efforts were also taken to use these films in dye-sensitized solar cells after introducing cis-dithiocyanato (4,4'-dicarboxylic acid-2,2'-bipyridide) ruthenium (II) (N3) dye but no significant improvement due to low contact angle in photo-electrochemical cell performance was observed due to high compactness

2005-06-15

91

Structural, morphological and local electric properties of TiO2 thin films grown by pulsed laser deposition  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (? = 266 nm, ?FWHM ? 5 ns, ? = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters

2007-09-07

92

Role of oxygen vacancies in anodic TiO2 thin films  

International Nuclear Information System (INIS)

Defects play an important role in the electronic and optical properties of amorphous solids in general. Here we present both experimental and theoretical investigations on the nature and origin of defect states in anodic rutile TiO2 thin films (of thickness 5nm to 20nm). There is experimental evidence that the observed gap state at 0.7eV below the edge of conduction-band is due to an oxygen vacancy. For this reason, oxygen vacancies are used in our model. A comparison of the calculated bulk-photoconductivity to photospectroscopy experiment reveals that the films have bulk-like transport properties. On the other hand a fit of the surface density of states to the scanning tunneling microscopy (STM) on the (001) surfaces has suggested a surface defect density of 5% of oxygen vacancies. To resolve this discrepancy, we calculated the dc-conductivity where localization effects are included. Our results show an impurity band formation at about pc=9% of oxygen vacancies. We concluded that the gap states seen in STM are localized and the oxygen vacancies are playing the role of trapping centers (deep levels) in the studied films. (author). 15 refs, 5 figs

1992-01-01

93

Ferromagnetism and structure of epitaxial Cr-doped anatase TiO2 thin films  

Energy Technology Data Exchange (ETDEWEB)

The materials and magnetic properties of Cr-doped anatase TiO2 thin films deposited on LaAlO3(001) and SrTiO3(001) substrates by oxygen-plasma-assisted molecular beam epitaxy have been studied in detail to elucidate the origin of ferromagnetic ordering. Cr substitution for Ti in the anatase lattice, with no evidence of Cr interstitials, segregation, or secondary phases, was independently confirmed by transmission electron microscopy (TEM) with energy dispersive x-ray (EDX) spectroscopy, extended x-ray absorption fine structure (EXAFS), and Rutherford backscattering spectrometry (RBS) in the channeling geometry. Epitaxial films deposited at ~0.1 Å/s were found to have a highly defected crystalline structure, as quantified by high resolution x-ray diffraction (XRD). These films were also ferromagnetic at room temperature with a moment of ~0.5 ?B/Cr, Curie temperatures in the range of 400 – 700°C, and exhibited shape and in-plane magnetocrystalline anisotropy. However, no free carrier spin polarization was observed by Hall effect measurements, raising questions about the mechanism of magnetism. Films deposited slowly (~0.015 Å/s) possessed a nearly perfect crystalline structure as characterized by XRD. Contrary to expectations, these films exhibited negligible ferromagnetism at all Cr concentrations. Annealing in vacuum to generate additional oxygen defects and free carrier electrons did not significantly increase the ferromagnetic ordering in either fast- or slow-grown films. These results contradict both oxygen-vacancy-derived free-carrier-mediated exchange and F-center-mediated bound magnetic polaron exchange mechanisms, and instead indicate the primary role of extended structural defects in mediating the ferromagnetic ordering in doped anatase films.

Kaspar, Tiffany C.; Droubay, Timothy; Shutthanandan, V.; Heald, Steve M.; Wang, Chong M.; McCready, David E.; Thevuthasan, Suntharampillai; Bryan, J. D.; Gamelin, Daniel R.; Kellock, A. J.; Toney, Michael F.; Hong, X.; Ahn, Charles; Chambers, Scott A.

2006-04-01

94

Synthesis, phase to phase deposition and characterization of rutile nanocrystalline titanium dioxide (TiO2) thin films  

International Nuclear Information System (INIS)

Highlights: ? Nanocrystalline rutile TiO2 thin film has been deposited by e-beam physical vapor deposition (EBPVD) method. ? A vacuum compatible target material (TiO2) was indigenously prepared for such deposition. ? A phase to phase (rutile to rutile) transformation was observed employing various characterization tools (XRD, RAMAN, UV–vis, FTIR and AFM). ? A process induced self annealing phenomenon shows a strong effect on the structural, morphological and optical properties of deposited thin films. ? The deposited film has sufficient possibility to realize a novel thin film material in the fabrication of active devices. - Abstract: In this work the preparation, deposition and structural properties of titanium oxide (TiO2) thin films were investigated. The films were deposited by means of the e-beam physical vapor deposition (EBPVD) method in high vacuum (10?7 Torr). A controlled deposition rate in the range of 0.1–0.3 ?/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (1 0 0) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV–visible Spectroscopy (UV–vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO2 layer between TiO2 and the substrate and the minor anatase crystalline phase of TiO2 was also identified in FTIR analysis. Grain size was found to be in the range of 100–125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO2 target to thin film.

2013-01-01

95

Electrical property measurements of Cr-N codoped TiO2 epitaxial thin films grown by pulsed laser deposition,  

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The temperature dependent resistivity and thermo-electric power of Cr-N codoped TiO2 were compared with that of single element N and Cr doped and undoped TiO2 using epitaxial anatase thin films grown by pulsed laser deposition on (100) LaAlO3 substrates. The resistivity plots and especially the thermoelectric power data confirm that codoping is not a simple sum of single element doping. However, the negative sign of the Seebeck coefficient indicates electron dominated transport independent of...

Jacimovic, Jacim; Gaal, Richard; Magrez, Arnaud; Forro?, La?szlo?; Regmi, Mauri; Eres, Gyula

2013-01-01

96

Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization  

Science.gov (United States)

Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities.

Ni, Jiahua; Frandsen, Christine J.; Noh, Kunbae; Johnston, Gary W.; He, Guo; Tang, Tingting; Jin, Sungho

2014-01-01

97

A spectroscopic ellipsometry study of TiO2 thin films prepared by dc reactive magnetron sputtering: annealing temperature effect  

International Nuclear Information System (INIS)

TiO2 thin films are obtained by dc reactive magnetron sputtering. A target of titanium (99.995%) and a mixture of argon and oxygen gases are used to deposit TiO2 films on to silicon wafers (100). The crystalline structure of deposited and annealed film are deduced by variable-angle spectroscopic ellipsometry (VASE) and supported by x-ray diffractometry. The optical properties of the films are examined by VASE. Measurements of ellipsometry are performed in the spectral range O.72-3.55 eV at incident angle 75 degree. Several SE models, categorized by physical and optical models, are proposed based on the 'simpler better' rule and curve-fits, which are generated and compared to the experimental data using the regression analysis. It has been found that the triple-layer physical model together with the Cody-Lorentz dispersion model offer the most convincing result. The as-deposited films are found to be inhomogeneous and amorphous, whereas the annealed films present the phase transition to anatase and futile structures. The refractive index of TiO2 thin films increases with annealing temperature. A more detailed analysis further reveals that thickness of the top sub-layer increases, whereas the region of the bottom amorphous sub-layer shrinks when the films are annealed at 300 degree C. (authors)

2007-06-01

98

S180 cell growth on low ion energy plasma treated TiO 2 thin films  

Science.gov (United States)

X-ray photoelectron spectroscopy (XPS) was used to characterise the effects of low energy (S180 cell growth with different plasma treatments. This may be because cell growth on TiO 2 was mainly influenced by nano-surface characteristics of oxide films rather than surface chemistry.

Dhayal, Marshal; Cho, Su-In; Moon, Jun Young; Cho, Su-Jin; Zykova, Anna

2008-03-01

99

Structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique  

Science.gov (United States)

In this work, we report the structural, morphological, and optical properties of TiO2 thin films synthesized by the electro phoretic deposition technique. The TiO2 film was formed on a doped fluorine tin oxide (SnO2:F, i.e., FTO) layer and used as a photo electrode in a dye solar cell (DSC). Using spectroscopic ellipsometry measurements in the 200 to 800?nm wavelengths domain, we obtain a thickness of the TiO2 film in the range of 70 to 80?nm. Characterizations by X-ray diffraction and atomic force microscopy (AFM) show a polycrystalline film. In addition, AFM investigation shows no cracks in the formed layer. Using an ultraviolet–visible near-infrared spectrophotometer, we found that the transmittance of the TiO2 film in the visible domain reaches 75%. From the measured current–voltage or I-V characteristic under AM1.5 illumination of the formed DSC, we obtain an open circuit voltage Voc?=?628?mV and a short circuit current Isc?=?22.6??A, where the surface of the formed cell is 3.14?cm2.

2012-01-01

100

Structural and magnetic properties of epitaxial CrO2 thin films grown on TiO2 (001) substrates  

Science.gov (United States)

The structural and magnetic properties of epitaxial CrO2 thin films grown on (001)-oriented TiO2 substrates by atmospheric pressure chemical vapor deposition are investigated. Due to the competition between demagnetization and a relatively weak perpendicular magnetocrystalline anisotropy, the deposited CrO2 (001) films exhibit magnetic properties that are significantly different from CrO2 (100) and CrO2 (110) films grown on TiO2 substrates. Based on the thickness dependence of M-H curves, a surface anisotropy is confirmed to exist, likely originating from strain in the film. The out-of-plane hysteresis curves can be well described by a distribution of effective anisotropy that may be due to a varying local demagnetizing field and a distribution of strain across the film. For the in-plane magnetization, the hysteresis curves are consistent with stripe or vortex domain structures of an almost closed flux configuration at remanence.

Zhang, Xueyu; Zhong, Xing; Visscher, P. B.; LeClair, Patrick R.; Gupta, Arunava

2013-04-01

 
 
 
 
101

TiO2 nanocrystals - MEH-PPV composite thin films as photoactive material  

International Nuclear Information System (INIS)

The optoelectronic processes occurring in colloidal anatase TiO2 nanocrystals/MEH-PPV conjugated polymer blends are reported. Composite films were prepared by spin-coating an homogeneous solution of low molecular weight MEH-PPV and surfactant-capped TiO2 nanocrystals onto low resistivity ITO substrates. Both nearly spherical and rod-like titania nanoparticles were used in the hybrid structures and the resulting blends comparatively examined, as a function of TiO2 nanoparticle morphology. The photoinduced charge transfer and recombination processes at the interface between the two components were studied by steady-state optical spectroscopy and photoelectrochemical experiments. A significant fluorescence quenching of the polymer occurred in MEH-PPV/TiO2 nanorods hetero-junctions and higher photoactivity of as prepared blends compared to the single components was observed and explained

2004-03-22

102

Effects of LP-MOCVD prepared TiO2 thin films on the in vitro behavior of gingival fibroblasts  

International Nuclear Information System (INIS)

We report on the in vitro response of human gingival fibroblasts (HGF-1 cell line) to various thin films of titanium dioxide (TiO2) deposited on titanium (Ti) substrates by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The aim was to study the influence of film structural parameters on the cell behavior comparatively with a native-oxide covered titanium specimen, this objective being topical and interesting for materials applications in implantology. HGF-1 cells were cultured on three LP-MOCVD prepared thin films of TiO2 differentiated by their thickness, roughness, transversal morphology, allotropic composition and wettability, and on a native-oxide covered Ti substrate. Besides traditional tests of cell viability and morphology, the biocompatibility of these materials was evaluated by fibronectin immunostaining, assessment of cell proliferation status and the zymographic evaluation of gelatinolytic activities specific to matrix metalloproteinases secreted by cells grown in contact with studied specimens. The analyzed surfaces proved to influence fibronectin fibril assembly, cell proliferation and capacity to degrade extracellular matrix without considerably affecting cell viability and morphology. The MOCVD of TiO2 proved effective in positively modifying titanium surface for medical applications. Surface properties playing a crucial role for cell behavior were the wettability and, secondarily, the roughness, HGF-1 cells preferring a moderately rough and wettable TiO2 coating.

2011-02-15

103

Synthesis and characterization of the Pd/InVO4-TiO2 co-doped thin films with visible light photocatalytic activities  

International Nuclear Information System (INIS)

Novel Pd/InVO4-TiO2 thin films with visible light photocatalytic activity were synthesized from the Pd and InVO2 co-doped TiO2 sol via sol-gel method. The photocatalytic activities of Pd/InVO4-TiO2 thin films were investigated based on the oxidative decomposition of methyl orange in aqueous solution. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis absorption spectroscopy (UV-vis). The results indicate that the Pd/InVO4-TiO2 thin films are compact, uniform and consist of sphere nanoparticles with diameters about 80-100 nm. The UV-vis spectra show that the Pd/InVO4-TiO2 thin films extend the light absorption spectrum toward the visible region. XPS results reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photocatalytic activities of InVO4-TiO2 thin films in decomposition of aqueous methyl orange under visible light irradiation. It has been confirmed that Pd/InVO4-TiO2 thin films could be excited by visible light (E 4 doped in the films

2006-12-15

104

Preparation and characterization of nanocrystalline TiO2 thin films  

International Nuclear Information System (INIS)

Nanocrystalline anatase TiO2 films have been prepared using sol-gel spin coating method. The sol has been prepared by mixing titanium isopropoxide with absolute ethanol and acetic acid at room temperature. The structural studies carried out revealed that the pristine films are amorphous in nature. The annealed films have been observed to be nanocrystalline in nature and the crystallinity has been observed to improve on annealing. The films are found to exhibit anatase phase with grain size of 19 nm and 22 nm for 450 deg. C and 550 deg. C annealed films. The high-resolution transmission electron microscope (HRTEM) image showed lattice fringes corresponding to the anatase phase of TiO2. The Raman spectra of the prepared films has been observed to be distinct without overlapping peaks suggesting that the prepared films have low level of impurity sites. The vibration peaks present in the spectra at 145 cm-1, 394 cm-1, 513 cm-1 and 635 cm-1 has been observed to unambiguously correspond to the Raman active modes of the anatase phase of TiO2.

2010-10-25

105

DIRECT PHOTODEPOSITION OF NANOSTRUCTURED TIO2 THIN FILMS FROM B-DIKETONATE COMPLEXES, AND THEIR PHOTOCATALYTIC BEHAVIOUR  

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Full Text Available Amorphous Titania thin films have been photochemically obtained by direct UV irradiation (254 nm of an amorphous TiO(C6H5COCHCOCH3 2 film spin-coated on Si(100 and borosilicate glass. These materials were characterized by scanning electron microscopy (SEM, X-ray diffraction spectroscopy (XRD and Auger electron spectroscopy (AES. SEM analysis showed a porous film with irregular morphology (diameter < 300 nm, whereas the XRD spectrum showed that the as-deposited film was completely amorphous and was transformed by annealing under nitrogen into polycrystalline TiO2. Subsequently, amorphous Titania deposited on borosilicate glass was used in the photocatalytic decomposition of aniline in water. The photoreaction of aniline was monitored by UV in the presence of air and nitrogen, and the product was characterized by infrared spectroscopy (IR. The results showed that aniline can be photooxidized efficiently by the TiO2/ borosilicate system in the presence of oxygen

M TEJOS

2004-12-01

106

Improved Energy Conversion Efficiency of TiO2 Thin Films Modified with Ta2O5 in Dye-Sensitized Solar Cells  

Science.gov (United States)

Tantalum-doped TiO2 thin films [(TiO2)1-x(Ta2O5)x, x=0{--}0.8%] were prepared on fluorine-doped tin oxide (FTO)-coated substrates by sol--gel technology for uses in dye-sensitized solar cells (DSSCs). The effects of Ta content on the growth and properties of the TiO2 thin films were investigated. The crystallization and microstructures of the thin films were examined by X-ray diffraction, scanning electron microscopy, and Brunauer--Emmett--Teller analyses. The performance of DSSCs based on Ta-doped TiO2 thin films was also studied. From the obtained results, the increases in Jsc and Voc may be due to the increased electron concentration of TiO2 thin film and the flat-band potential of the TiO2 shifted by tantalum doping, respectively. The optimum properties of DSSCs of Voc=0.68 V, Jsc=7.84 mA/cm2, FF=45.1%, and ?=2.4% were obtained using the Ta-doped TiO2 thin film with x=0.5%.

Kao, Ming-Cheng; Chen, Hone-Zern; Young, San-Lin

2013-01-01

107

Hysteretic current-voltage characteristics in RF-sputtered nanocrystalline TiO2 thin films  

International Nuclear Information System (INIS)

We have measured the current-voltage characteristics at room temperature of a nanocrystalline TiO2 thin film fabricated by reactive RF-sputtering deposition and sandwiched between ITO (indium-tin-oxide)-buffered glass substrate and an indium top electrode. The I-V characteristics are ohmic for low voltages and become non-linear, hysteretic and asymmetric as the voltage is increased. The system is shown to be well represented by two distinct resistance states in the non-ohmic region. Current transient evolutions were also measured for constant voltage excitations. The resistance is stable in time for voltages in the ohmic regime. In contrast, for voltages in the non-ohmic regime, the resistance has a small variation for a short period of time (order of tens seconds) and then increases with time. For those transients, long characteristic times (on the order of tens of minutes up to hours) were found. The behavior of the system is discussed on the basis of experimental results reported in the literature for similar systems and existing models for electric-field induced resistive switching

2007-09-01

108

Localised modifications of anatase TiO2 thin films by a Focused Ion Beam  

International Nuclear Information System (INIS)

A Focused Ion Beam (FIB) has been used to implant micrometer-sized areas of polycrystalline anatase TiO2 thin films with Ga+ ions using fluencies from 1015 to 1017 ions/cm2. The evolution of the surface morphology was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the chemical modifications of the surface were followed by X-ray photoelectron spectroscopy (XPS). The implanted areas show a noticeable change in surface morphology as compared to the as-deposited surface. The surface loses its grainy morphology to gradually become a smooth surface with a RMS roughness of less than 1 nm for the highest ion fluence used. The surface recession or depth of the irradiated area increases with ion fluence, but the rate with which the depth increases changes at around 5 x 1016 ions/cm2. Comparison with implantation of a pre-irradiated surface indicates that the initial surface morphology may have a large effect on the surface recession rate. Detailed analysis of the XPS spectra shows that the oxidation state of Ti and O apparently does not change, whereas the implanted gallium exists in an oxidation state related to Ga2O3.

2010-10-01

109

Co-doped rutile TiO2-? thin films studied by XANES and first principles calculations  

International Nuclear Information System (INIS)

The x-ray absorption near-edge structure (XANES) and first-principles calculations were employed to study the local structure and magnetic origin of Co-doped rutile TiO2 thin film. It is found that the experimental Co K-edge XANES can be reproduced by the calculated spectrum of substitutional Co (CoTi) with O vacancy (VO), suggesting the coexistence of CoTi and VO in this system. First-principles total energy calculations further reveal that the O vacancy prefers to reside near the Co ion and substantially facilitates the impurity doping. The electronic structure analysis indicates that the O vacancy can mediate the ferromagnetic interaction between the CoTi ions and thus is responsible for the observed room-temperature ferromagnetism in the Co-doped TiO2-? thin films.

2009-11-01

110

Effect of thermal annealing on the structural properties of TiO2 thin film prepared by RF sputtering  

International Nuclear Information System (INIS)

It was presented the structural properties of a titanium dioxide thin film which is prepared by RF magnetron sputtering system on p-type (100) Si substrate with Ar (70 percent) and O (30 percent) atmosphere. The film was conventionally thermal annealed at 500 degrees Celsius, 800 degrees Celsius, 1000 degrees Celsius during 1 hour and 1000 degrees Celsius during 2 hours under air atmosphere. The structural properties of films were investigated by using high resolution x-ray diffraction system and Fourier transform infrared spectroscopy in range from 375 to 8000 sm-1 for as-deposited films and annealed films. Also, chemical bonding structures of the thin film were explained. As-deposited film has anatase phase. However, in annealed films anatase and rutile phases coexist as revealed by XRD and infrared spectroscopy. Also, it is observed that during growth and the annealing of the TiO2 film, thin SiO2 layer was formed at the TiO2 and Si interface

2010-06-01

111

Laser damage properties of TiO2/Al2O3 thin films grown by atomic layer deposition  

International Nuclear Information System (INIS)

Research on thin film deposited by atomic layer deposition (ALD) for laser damage resistance is rare. In this paper, it has been used to deposit TiO2/Al2O3 films at 110 deg. C and 280 deg. C on fused silica and BK7 substrates. Microstructure of the thin films was investigated by x-ray diffraction. The laser-induced damage threshold (LIDT) of samples was measured by a damage test system. Damage morphology was studied under a Nomarski differential interference contrast microscope and further checked under an atomic force microscope. Multilayers deposited at different temperatures were compared. The results show that the films deposited by ALD had better uniformity and transmission; in this paper, the uniformity is better than 99% over 100 mm ? samples, and the transmission is more than 99.8% at 1064 nm. Deposition temperature affects the deposition rate and the thin film microstructure and further influences the LIDT of the thin films. As to the TiO2/Al2O3 films, the LIDTs were 6.73±0.47 J/cm2 and 6.5±0.46 J/cm2 at 110 deg. C on fused silica and BK7 substrates, respectively. The LIDTs at 110 deg. C are notably better than 280 deg. C.

2011-08-20

112

Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2–Cu2O thin films  

Science.gov (United States)

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO2–Cu2O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ?172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO2, the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required.

Aytug, Tolga; Bogorin, Daniela F.; Paranthaman, Parans M.; Mathis, John E.; Simpson, John T.; Christen, David K.

2014-06-01

113

TRANSPARENT SUPERHYDROPHILIC SiO2/TiO2/SiO2 TRI-LAYER NANOSTRUCTURED ANTIFOGGING THIN FILM  

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Full Text Available SiO2/TiO2/SiO2 thin films were deposited on glass substrates using an electron beam physical vapor deposition technique. The structure, morphology, surface composition, surface roughness, optical properties, and hydrophilic properties of the thin film were investigated. The structure measurement shows that only anatase phase was exhibited in the thin film. In the TiO2 thin film, the crystals nucleated from the thin films was homogeneous and the average crystalline sizes were 35 nm. The transmittance spectra of the films revealed transparency in the visible region of the spectrum. SiO2/TiO2/SiO2 thin film showed better hydrophilicity under irradiation and storage in comparison to SiO2/TiO2 thin film. SiO2/TiO2/SiO2 tri-layer thin film showed superhydrophilicity which greatly encourages the antifogging function of the film.

Eshaghi A.

2013-09-01

114

Microwave-assisted synthesis and characterization of poly(acrylic)/SiO2-TiO2 core-shell nanoparticle hybrid thin films  

International Nuclear Information System (INIS)

In this study, poly(acrylic)/SiO2-TiO2 core-shell nanoparticle hybrid thin films were successfully synthesized by microwave-assisted polymerization. The coupling agent 3-(trimethoxysilyl) propyl methacrylate (MSMA) was hydrolyzed with colloidal SiO2-TiO2 core-shell nanoparticles, and then polymerized with two acrylic monomers and initiator to form a precursor solution. The results of this study showed that the spin-coated hybrid films had relatively good surface planarity, high thermal stability, a tunable refractive index (1.525 2-TiO2 core-shell nanoparticle hybrid thin films, for potential use in optical applications.

2011-05-31

115

Semiconductor TiO2-Ga2O3 thin film gas sensors derived from particulate sol-gel route  

International Nuclear Information System (INIS)

Nanostructured and mesoporous TiO2-Ga2O3 thin films with various Ti:Ga atomic ratios were prepared by a new straightforward particulate sol-gel route. Titanium isopropoxide and gallium (III) nitrate hydrate were used as precursors, and hydroxypropyl cellulose (HPC) was used as a polymeric fugitive agent (PFA) in order to increase the specific surface area (SSA). XRD and TEM analysis of the powders revealed that the Ga2O3 formed from the nitrate precursor retarded anatase-to-rutile transformation, crystallization and crystal growth. The average crystallite size of pure TiO2 powder annealed at 600-1000 deg. C were in the range 4-10 nm; the values that could be decreased to 2-6 nm for TiO2-Ga2O3 powders. Furthermore, one of the highest SSA was obtained by introducing Ga2O3 into TiO2, being 305 m2 g-1 for TG11 (Ti:Ga = 50:50 atomic ratio) binary oxide annealed at 600 deg. C. Thin films produced under optimized conditions showed excellent microstructural properties for gas sensing applications. They exhibited a remarkable response towards low concentrations of CO and NO2 gases at low operating temperature of 200 deg. C, resulting in increased thermal stability of sensing films as well as a decrease in their power consumption. TG11 sensor showed the highest response towards all CO and NO2 concentrations operated at 200 deg. C. The response magnitude of 13.7 and 4.3 with response times of 30 s and 108 s were achieved for TG11 sensor towards 400 ppm CO and 10 ppm NO2, respectively. Furthermore, calibration curves revealed that TiO2-Ga2O3 sensors follow the power law (S = A[gas] B) (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration) for the two types of gases, and they have excellent capability for the detection of low gas concentrations (25 ppm CO and 0.5 ppm NO2). The maximum response of TiO2-Ga2O3 sensors towards CO and NO2 was measured at 450 and 400 deg. C, respectively. The sensor response decreased with increasing film annealing temperature owing to sintering of the particles. The response magnitude and response time of the sensors obtained in this work is superior to TiO2-based sensors reported in previous studies

2007-08-01

116

An electrochemical strategy to incorporate nitrogen in nanostructured TiO2 thin films: modification of bandgap and photoelectrochemical properties  

Science.gov (United States)

We describe a simple and facile electrochemical method to introduce anionic dopants into TiO2. N-doped thin films with chemical composition TiO2-xNx, up to x = 0.23, were fabricated by anodic oxidation of a pure titanium sheet in electrolyte solutions containing ammonium ions, nitrate ions and fluoride ions enabling simultaneous nanostructuring and doping of the growing anodic oxide. Analysis by x-ray photoelectron spectroscopy (XPS) indicates that nitrogen atoms substitute for oxygen sites within the TiO2. F atoms were present in the amorphous, as-anodized samples but were resubstituted by O atoms upon annealing in oxygen at temperatures higher than 600 °C. For nitrogen doped films UV-vis spectroscopy indicates a shift in the primary absorption threshold as well as significant optical absorption in the visible wavelength range from 400 to 530 nm. The concentration of the incorporated anionic dopants, and the morphology of the doped thin film are strong functions of electrolyte chemistry and anodization time. Longer anodization periods resulted in a well-developed nanotube-array structure but smaller amounts of incorporated nitrogen. XPS depth profiling reveals the nitrogen doping to be inhomogeneous, with maximum nitrogen incorporation occurring near the oxide-electrolyte interface at the surface of the anodized film.

Shankar, Karthik; Chhay Tep, Kong; Mor, Gopal K.; Grimes, Craig A.

2006-06-01

117

Enhancement of photoelectric and photocatalytic activities: Mo doped TiO2 thin films deposited by sputtering  

International Nuclear Information System (INIS)

TiO2 thin films doped with different contents of Mo were deposited by DC reactive magnetron sputtering. Surface morphology, crystal structure, elements' valence states and absorption edge of each sample were characterized by atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet–visible spectrometer. Cyclic voltammetry was utilized to study the photoelectric properties while the photocatalytic activity was evaluated by the degradation rate of methylene blue. The result indicates that an appropriate concentration of Mo could extend the absorption edge of TiO2 film to visible range remarkably. When the content reached 0.9 at.%, with a xenon lamp we observed the strongest photocurrent as well as the best photocatalytic property while under the illumination of strong visible light, a photocurrent 10 times the undoped sample appeared. The electrochemical impedance spectroscopy observed the fastest speed of carrier transfer as doping content increased to 0.9 at.%, while higher doping amount would precipitate carrier recombination due to a large number of lattice defects. - Highlights: ? Mo-doped TiO2 thin films were deposited by DC reactive magnetron sputtering. ? Doped films present high specific area and well-grown crystals. ? Proper content of Mo accelerates charge separation and inhibits the recombination. ? Enhanced photocatalytic activity under ultraviolet light is attained by doping. ? Under visible light, the strongest photocurrent after doping increases tenfold!

2012-11-01

118

An electrochemical strategy to incorporate nitrogen in nanostructured TiO2 thin films: modification of bandgap and photoelectrochemical properties  

International Nuclear Information System (INIS)

We describe a simple and facile electrochemical method to introduce anionic dopants into TiO2. N-doped thin films with chemical composition TiO2-xNx, up to x = 0.23, were fabricated by anodic oxidation of a pure titanium sheet in electrolyte solutions containing ammonium ions, nitrate ions and fluoride ions enabling simultaneous nanostructuring and doping of the growing anodic oxide. Analysis by x-ray photoelectron spectroscopy (XPS) indicates that nitrogen atoms substitute for oxygen sites within the TiO2. F atoms were present in the amorphous, as-anodized samples but were resubstituted by O atoms upon annealing in oxygen at temperatures higher than 600 deg. C. For nitrogen doped films UV-vis spectroscopy indicates a shift in the primary absorption threshold as well as significant optical absorption in the visible wavelength range from 400 to 530 nm. The concentration of the incorporated anionic dopants, and the morphology of the doped thin film are strong functions of electrolyte chemistry and anodization time. Longer anodization periods resulted in a well-developed nanotube-array structure but smaller amounts of incorporated nitrogen. XPS depth profiling reveals the nitrogen doping to be inhomogeneous, with maximum nitrogen incorporation occurring near the oxide-electrolyte interface at the surface of the anodized film

2006-06-07

119

Electrical and optical properties of the hybrid TiO2 nanocrystals - MEH-PPV thin films  

International Nuclear Information System (INIS)

Recently, the conjugated polymer-inorganic nanocomposites have been increasingly studied because of their enhanced optical and electronic properties as well as their potential application in developing optoelectronic devices. In this study nanocomposite materials thin films based on poly [2-methoxy-5-(2-ethyl-hexyloxy) - 1,4- phenylene vinylene] (MEH-PPV) and nanocrystalline TiO2 (nc-TiO2) have been fabricated. The photoluminescence (PL) spectra of pure MEN-PPV and nanohybrid films have shown that the excitation at a 377 nm wavelength leads to the strongly enhanced performance in photoluminescent intensity due to the compositions of TiO2 component. Current-voltage (I-V) characteristics of multi-layer device Al/ /MEH-PPV; nc-TiO2/ /PEDOT: PSS/ /ITO/ /glass were investigated. the results show that the hybrid MEH-PPV: nc-TiO2 materials with high concentrations of TiO2 (>25 %) can be expected to be a good candidate for photovoltaic solar cell applications whereas hose with lower concentrations of TiO2 are more suitable for organic light-emitting diodes (OLEDs). (author)

2009-12-01

120

Microstructure and optical properties of TiO2 thin films prepared by low pressure hot target reactive magnetron sputtering  

International Nuclear Information System (INIS)

Thin films of TiO2 were deposited onto (1 0 0) oriented silicon and glass substrates using modified magnetron sputtering method. The method, among the others, consisted in employing low pressure of reactive gas (-1 Pa), hot target (additional heating of the target) and low deposition rate (about 0.1 nm/s). X-ray diffraction, X-ray photoelectron spectroscopy and optical transmission measurements have been applied to study the influence of film thickness, substrate type and post annealing process on the microstructure, composition, and optical properties of prepared thin films. It was found that the lattice spacings were a bit smaller than those of bulk material what indicated the contraction of the thin film. Optical examinations have shown that the fundamental absorption edge was shifted toward longer wavelength region (from 330 to 351 nm) as the thickness of the film increased. It was stated that thin films of TiO2 were almost stoichiometric after additional annealing

2006-08-14

 
 
 
 
121

CrO2 thin films epitaxially grown on TiO2 (001): Electronic structure and magnetic properties  

Science.gov (United States)

CrO2 thin films epitaxially grown on the rutile TiO2 (001) substrate are studied via density function theory. Due to the strain from the substrate, a semiconductor to half-metal transition with the film growth is observed. It is found that, as the film is thicker than three atomic layers, the half-metallic property can be retained with an antiferromagnetic feature which reduces the total magnetic moment. With the help of ionic and the double exchange picture, the physics behind the half-metallic rebuilding process is revealed.

Huang, Xing; Yan, X. H.; Zhu, Z. H.; Yang, Y. R.; Guo, Y. D.

2011-03-01

122

Anisotropic laser-induced damage threshold and residual stress of TiO2 sculptured thin films.  

Science.gov (United States)

The residual stress and laser-induced damage threshold (LIDT) of TiO2 sculptured thin films prepared by glancing angle electron beam evaporation were studied. UV-Vis-NIR spectra and optical interferometer were employed to characterize the optical and mechanical properties, respectively. Optical microscopy and Raman spectra were used to observe damage morphology and analyze damage microstructure, respectively. It was found that the residual stress changed from compressive into tensile with increasing deposition angle. The LIDT was anisotropic with p- and s-polarization light, which was due to the anisotropic nanostructure and optical properties. Simultaneously, an optimum deposition angle for the maximum threshold of TiO2 film was about 60 degrees. The mechanism of laser-induced damage was thermal in nature. The process of thermal damage with crystallization is proved by Raman spectra. PMID:23646523

Xiao, Xiudi; Miao, Lei; Zhang, Ming; Xu, Gang; Shao, Jianda; Fan, Zhengxiu

2013-02-01

123

Third-order optical nonlinearities in anatase and rutile TiO2 thin films  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) films have been fabricated on fused quartz and Si(001) substrates by pulsed laser deposition technique and the single-phase anatase and rutile films were obtained under the optimal conditions. The surface images and optical transmission spectra were investigated by scanning electron microscopy and double beam spectrophotometer, respectively. The values of optical band-gap and linear refractive index of the anatase and rutile films were determined. The optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50 fs) at the wavelength of 800 nm. Through the open-aperture and closed-aperture Z-scan measurements, the real and imaginary parts of the third-order nonlinear optical susceptibility were calculated and the results show that the anatase phase TiO2 films exhibit larger nonlinear refractive effects compared with rutile phase. The figure of merit, T, defined by T = ??/n2, was calculated to be 0.8 for anatase films, meeting the requirement of T < 1 and showing potential applications in all-optical switching devices.

2009-08-03

124

Determination of thermo-optic properties of atomic layer deposited thin TiO2 films for athermal resonant waveguide gratings by spectroscopic ellipsometry  

Science.gov (United States)

We report on variation in the refractive index of amorphous and isotropic TiO2 thin films grown by Atomic Layer Deposition (ALD) in nano optical devices. ALD-TiO2 films of thicknesses ALD-TiO2 films with thicknesses > 200 nm show positive TOC due to the predominance of TiO2 thickness over the very thin surface porosity region. The negative TOC of thin TiO2 films was controlled by depositing thin ALD-Al2O3 diffusion barrier films that showed impermeable behavior to block the evaporation of adsorbed water molecules on TiO2 surfaces in thermal environments. This approach turns negative sign of TOC of TiO2 thin films to positive one which is necessary to stabilize the central resonance peak of a guided mode resonance filter (GMRF). The ALD-TiO2 and ALDAl2O3 bi-layer stack was modeled by VASE analysis of spectroscopic ellipsometry using Cauchy Model to extract refractive indices at various temperatures, measured at two different angle of incidence (65° and 75°), covering a wide spectral range 380 <= ? <= 1800. The temperature dependent index and density of TiO2 films were calculated from ellipsometric measured data using Lorentz-Lorenz relation.

Saleem, Muhammad Rizwan; Ali, Rizwan; Honkanen, Seppo; Turunen, Jari

2014-05-01

125

An In-situ Real-Time Optical Fiber Sensor Based on Surface Plasmon Resonance for Monitoring the Growth of TiO2 Thin Films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in r...

Yu-Chia Tsao; Woo-Hu Tsai; Wen-Ching Shih; Mu-Shiang Wu

2013-01-01

126

The antibacterial and hydrophilic properties of silver-doped TiO2 thin films using sol-gel method  

Science.gov (United States)

Ag-TiO2 composite thin films were deposited on glass slides by sol-gel spin coating technique. The surface structure, chemical components and transmittance spectra were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectrophotometer. The TiO2 thin films with silver molar ratio from 0 to 10% were tested for its antibacterial property by using Escherichia coliform (E. coli) under irradiation of UV light. The concentration of E. coli was evaluated by plating technique. The influences of different molar ratio of Ag on hydrophilicity and long-term durability of the films were also investigated by measuring the water contact angle. The results showed that the antibacterial ability was significantly improved by increasing silver content comparing with pure TiO2 thin film, and the best molar ratio of Ag was 5%. While the hydrophilicity of films increased with increasing silver content, and the best molar ratio of Ag was 1%.

Wang, Xuemin; Hou, Xinggang; Luan, Weijiang; Li, Dejun; Yao, Kun

2012-08-01

127

Angle dependence of the O K edge absorption spectra of TiO2 thin films with preferential texture  

International Nuclear Information System (INIS)

O K and Ti L2,3 edge X-ray absorption spectra have been recorded for TiO2 thin films (?100 nm thickness) prepared by ion beam induced CVD at room temperature. The as prepared films were amorphous but they crystallize into the anatase structure of TiO2 after annealing at T>650 K. In the amorphous films, the magnitude of the crystal field, determined from the evaluation of the spectra, was smaller than in the well crystallized anatase samples. In these latter samples the O K edge spectra show a strong dependence on the angle of incidence of the radiation with respect to the sample surface. This dependence rises some concerns about the use of the O K edge spectra of oxide materials for a universal 'fingerprint' characterization of thin films. A preliminary theoretical evaluation of the evolution of the t2g/eg intensity ratio with the relative orientation of the electric field of the radiation and the surface normal of the samples is carried out. For this evaluation, the texture of the thin film (i.e. the preferential growth of certain crystallographic planes parallel to the surface) and the existence of surface modifications of the environment around the Ti are taken into account

2003-01-01

128

TiO2 thin film encapsulated ZnO nanorod and nanoflower dye sensitized solar cells  

International Nuclear Information System (INIS)

The performance of dye-sensitized solar cells based on ZnO nanorods and nanoflowers coated with thin shells of TiO2 thin film prepared by sol-gel deposition are described. It is found that shells act as insulating barriers that improve cell open-circuit voltage and short-circuit current density. The superior performance of the ZnO-TiO2 core-shell cells is a result of a radial electron transport within each ZnO nanorods and nanoflowers that decreases the rate of recombination and percolation of the electron in these devices.

2011-01-01

129

Influence of TiO2 particles on PVB foils used in silicon based thin film photovoltaic modules  

Science.gov (United States)

Transparent PVB lamination foils are widely used in thin-film solar modules. The application of a pigmented load composed by TiO2 particles in the foil formulation does not only influence the reflectance properties of this material, it has also a remarkable impact on other material parameters like resistivity and adhesion. The main objective of this study is to illustrate the properties of white lamination films based on polyvinyl butyral materials. A special insight will be on adhesion, foil resistivity and activation energies. Some performance results on modules will be also presented.

Sinicco, Ivan; Gossla, Mario; Krull, Stefan; Rakusa, Fabia; Roth, Florian

2010-08-01

130

Nanoindentation of TiO2 thin films with different microstructures  

International Nuclear Information System (INIS)

A series of nanoindentation tests has been carried out with TiO2 films produced by physical vapour deposition (PVD) under different conditions. Films with different microstructures and crystallographic structures have been prepared by changing experimental parameters such as the temperature of the substrate, the deposition angle (by the so-called glancing angle physical vapour deposition, GAPVD) or by exposing the growing film to a beam of accelerated ions. The obtained results of hardness and Young's modulus depict interesting correlations with the microstructure and structure of the films providing a general picture for the relationships between these characteristics and their mechanical properties. Different models have been used to extract Young's modulus and hardness parameters from the experimental nanoindentation curves. The obtained results are critically discussed to ascertain the ranges of validity of each procedure according to the type of sample investigated.

2009-07-21

131

X-ray spectroscopic methods in the studies of nonstoichiometric TiO2-x thin films  

Science.gov (United States)

X-ray spectroscopic techniques have been used in the studies of electronic and structural properties of nonstoichiometric TiO2-x thin films obtained by reactive sputtering from Ti target. Films characterisation has been completed by means of X-ray diffraction in grazing incidence, GID, UV Raman and impedance spectroscopy, optical spectrophotometry, 1s3p Resonant X-ray Emission Spectroscopy, RXES, and X-ray Photoelectron Spectroscopy, XPS. Stoichiometric thin films of TiO2 are composed of a well-crystallised anatase-rutile mixture with the predominance of anatase while the films with higher oxygen deficit are amorphous to larger extent. Oxidation state changes from Ti4+ in stoichiometric films towards Ti3+ upon increasing departure from stoichiometric composition. This change is accompanied by the significant decrease in the electrical resistivity. The comparison of band gap energies, determined independently from optical and valence band X-ray absorption/emission spectra is good assuming direct allowed transitions.

Kollbek, K.; Sikora, M.; Kapusta, Cz.; Szlachetko, J.; Zakrzewska, K.; Kowalski, K.; Radecka, M.

2013-09-01

132

Preparation and characterization of Fe2O3-TiO2 thin films on glass substrate for photocatalytic applications  

International Nuclear Information System (INIS)

Fe2O3-TiO2 coatings were successfully prepared on glass slide substrates using sol-gel method for photocatalytic applications. The phase structure, thermal, microstructure and surface properties of the coatings were extensively characterized by using X-ray diffractometry (XRD), differential thermal analysis/thermograviometry (DTA/TG), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Their adhesion and absorbance properties were investigated by a scratch tester and UV-vis spectroscopy. Four different solutions were prepared by changing Fe/Ti molar ratios. Glass substrates were coated by solutions of Ti-alkoxide, Fe-chloride, glaciel acetic acid and isopropanol. The obtained gel films were dried at 300 deg. C for 10 min and subsequently heat-treated at 500 deg. C for 5 min in air. The oxide thin films were annealed at 600 deg. C for 60 min in air. The influence of Fe3+ concentration and number of layers on structure of the films was established. In addition, XRD results revealed that Fe2O3-TiO2 films composed of TiO2, Fe2Ti3O9, Ti3O5 and Fe3O4 phases. According to DTA/TG result, it was determined that endothermic and exothermic reactions were formed at temperatures between 80 and 650 deg. C due to solvent removal, combustion of carbon based materials and oxidation of Fe and Ti. SEM observations exhibited that the coating structure becomes more homogeneous depending on an increase of Fe/Ti molar ratios and thus a regular surface morphology forms with increasing Fe/Ti ratio. It was also seen that as the Fe/Ti ratio increases the surface roughness of the films increases. Critical adhesion force of thin films with Fe/Ti ratio of 0, 0.07, 0.18 and 0.73 were found to be 9, 25, 28 and 21 mN, respectively. The methylene blue solutions photocatalyzed by TiO2 based thin films shows characteristic absorption bands at 420 nm

2006-04-15

133

Fabrication and Characterization of Hydrophilic TiO2 Thin Films on Unheated Substrates Prepared by Pulsed DC Reactive Magnetron Sputtering  

International Nuclear Information System (INIS)

TiO2 thin films were deposited on unheated silicon wafers (100) and glass slides by a pulsed DC reactive magnetron sputtering in an ultrahigh vacuum (UHV) system. The effects of both an operating pressure and deposition time on film structure, surface morphology, and optical property were studied. The film structure and microstructure were characterized by grazing-incidence X-ray diffraction (GIXRD) technique and transmission electron microscopy (TEM). The surface morphology was investigated by field emission scanning electron microscopy (FE-SEM). The optical property of the TiO2 thin films was determined by spectroscopic ellipsometry (SE). The water contact angle measurement was also used to determine hydrophilicity of the films after exposed to UV light. The results suggested that the TiO2 thin film at less than 40?nm was amorphous. As the thickness was increased, the mixture of anatase and rutile phases of TiO2 began to form. By reducing the operating pressure during the film deposition, the rutile phase component can also be enhanced. Both the increased film thickness and decrease operating pressure were the critical factors to improve the hydrophilicity of the TiO2 thin films.

1212-01-00

134

Fabrication and Characterization of Hydrophilic TiO2 Thin Films on Unheated Substrates Prepared by Pulsed DC Reactive Magnetron Sputtering  

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Full Text Available TiO2 thin films were deposited on unheated silicon wafers (100 and glass slides by a pulsed DC reactive magnetron sputtering in an ultrahigh vacuum (UHV system. The effects of both an operating pressure and deposition time on film structure, surface morphology, and optical property were studied. The film structure and microstructure were characterized by grazing-incidence X-ray diffraction (GIXRD technique and transmission electron microscopy (TEM. The surface morphology was investigated by field emission scanning electron microscopy (FE-SEM. The optical property of the TiO2 thin films was determined by spectroscopic ellipsometry (SE. The water contact angle measurement was also used to determine hydrophilicity of the films after exposed to UV light. The results suggested that the TiO2 thin film at less than 40?nm was amorphous. As the thickness was increased, the mixture of anatase and rutile phases of TiO2 began to form. By reducing the operating pressure during the film deposition, the rutile phase component can also be enhanced. Both the increased film thickness and decrease operating pressure were the critical factors to improve the hydrophilicity of the TiO2 thin films.

M. Horprathum

2010-01-01

135

Thickness-dependent electron transport performance of mesoporous TiO2 thin film for dye-sensitized solar cells  

International Nuclear Information System (INIS)

Anatase titania (TiO2) nanocrystals with an average size of 12 nm were synthesized by combining sol–gel method and hydrothermal crystallization technology. Mesoporous TiO2 thin film electrodes (MTTFEs) were prepared by variations in layer of screen-printed TiO2 nanocrystals pastes, and dye-sensitized solar cells (DSCs) based on different thickness of MTTFEs were fabricated with dye C106. Under the irradiation of 100 mW cm?2 air mass 1.5 global (AM1.5G) sunlight, the short-circuit photocurrent density (Jsc) and overall conversion efficiency (?) was improved when the thickness of MTTFEs increased from 2.1 ?m to 9.8 ?m, and obvious decreases of the Jsc and ? were found when the film thickness was further increased over 9.8 ?m. The kinetic parameters of electron transport were investigated by the transient photoelectrical and electrical impedance measurements, and then the influence of MTTFEs thickness on electron transport performance in DSCs were further discussed. The results showed that the density of states (DOS) and recombination rate (Kr) increased with the MTTFEs thickness increasing. Furthermore, when the thickness of MTTFEs was in the range of 2.1–9.8 ?m, the electron lifetime (?n), the electron diffusion coefficient (Dn), and the electron diffusion length (Ln) of devices increased, but these parameters decreased gradually with the further increased thickness of MTTFEs, which influenced the electronic transport performance of DSCs

2013-12-30

136

Angle-resolved photoemission spectroscopy for VO2 thin films grown on TiO2 (0 0 1) substrates  

International Nuclear Information System (INIS)

We present the results of angle-resolved photoemission spectroscopy (ARPES) measurements of metallic VO2 thin films. The VO2 thin films have been grown on TiO2 (0 0 1) single crystal substrates using pulsed laser deposition. The films exhibit a first-order metal-insulator transition (MIT) at 305 K. In the ARPES spectra of the metallic phase for the films, the O 2p band shows highly dispersive feature in the binding energy range of 3-8 eV along the ?-Z direction. The periodicity of the dispersive band is found to be 2.2 A-1 which is almost identical with the periodicity expected from the c-axis length of the VO2 thin films. The overall feature of the experimental band structure is similar to the band structure calculations, supporting that we have succeeded in observing the dispersive band of the O 2p state in the metallic VO2 thin film. The present work indicates that the ARPES measurements using epitaxial thin films are promising for determining the band structure of VO2.

2010-08-01

137

Apatite formation from simulated body fluid on various phases of TiO2 thin films prepared by filtered cathodic vacuum arc deposition  

International Nuclear Information System (INIS)

Hydroxyl (OH-)-free TiO2 thin films with amorphous and crystalline phases were deposited onto (100) silicon substrates using filtered cathodic vacuum arc deposition in order to investigate the in vitro apatite formation in simulated body fluid (SBF). The surface morphology, composition and structure of the TiO2 thin films were characterized. The X-ray photoelectron spectroscopy results confirmed the presence of calcium and phosphorus on all TiO2 thin film surfaces after immersion in SBF at 37 oC. Fourier transform infra red results showed the presence of carbonated apatite on the surface of these films. Amorphous structured TiO2 thin film showed poor ability to form apatite on its surface in SBF. Apatite formation was more pronounced on the surfaces of the anatase films in comparison to those of rutile. The carbonated apatite deposition rate increased significantly when the TiO2 film was illuminated with UV light prior to immersing in the SBF. In particular, the UV-treated anatase and rutile films showed increased rates of carbonated apatite formation on their surfaces in comparison to samples not treated with radiation. The increase in hydrophilicity due to UV treatment appears beneficial for the apatite growth on these surfaces.

2010-12-01

138

Degradation of gas-phase trichloroethylene over thin-film TiO2 photocatalyst in multi-modules reactor  

International Nuclear Information System (INIS)

The present paper examined the photocatalytic degradation (PCD) of gas-phase trichloroethylene (TCE) over thin-film TiO2. A large-scale treatment of TCE was carried out using scale-up continuous flow photo-reactor in which nine reactors were arranged in parallel and series. The parallel or serial arrangement is a significant factor to determine the special arrangement of whole reactor module as well as to compact the multi-modules in a continuous flow reactor. The conversion of TCE according to the space time was nearly same for parallel and serial connection of the reactors.

2009-07-30

139

Femto- to Millisecond Photophysical Characterization of Indole-Based Squaraines Adsorbed on TiO2 Nanoparticle Thin Films  

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In this paper, we address femto- to millisecond transient absorption studies of TiO2 nanoparticle (NP) thin films sensitized with four squaraine (SQ) molecules, with and without a deaggregating agent, chenodeoxycholic acid (CDCA). On the femto- to picosecond time scale, we determined the presence of three transient species by using singular value decomposition (SVD) analysis, i.e., S-1 of the SQ monomers, S-1 of the SQ H-aggregates, and the SQ radical cation formed after the electron injectio...

2012-01-01

140

Synthesis of TiO2 thin films using single molecular precursors by MOCVD method for dye-sensitized solar cells application and study on film growth mechanism  

International Nuclear Information System (INIS)

For dye-sensitized solar cells application, in this study, we have synthesized TiO2 thin films at deposition temperature in the range of 300–750 °C by metalorganic chemical vapor deposition (MOCVD) method. Titanium(IV) isopropoxide, (TIP, Ti(OiPr)4) and Bis(dimethylamido)titanium diisopropoxide, (BTDIP, (Me2N)2Ti(OiPr)2) were used as single source precursors that contain Ti and O atoms in the same molecule, respectively. Crack-free, highly oriented TiO2 polycrystalline thin films with anatase phase were deposited on Si(1 0 0) with TIP at temperature as low as 450 °C. XRD and TED data showed that below 500 °C, the TiO2 thin films were dominantly grown in the [2 1 1] direction on Si(1 0 0), whereas with increasing the deposition temperature to 700 °C, the main film growth direction was changed to [2 0 0]. Above 700 °C, however, rutile phase TiO2 thin films have only been obtained. In the case of BTDIP, on the other hand, only amorphous film was grown on Si(1 0 0) below 450 °C while a highly oriented anatase TiO2 film in the [2 0 0] direction was obtained at 500 °C. With further increasing deposition temperatures over 600 °C, the main film growth direction shows a sequential change from rutile [1 0 1] to rutile [4 0 0], indicating a possibility of getting single crystalline TiO2 film with rutile phase. This means that the precursor together with deposition temperature can be one of important parameters to influence film growth direction, crystallinity as well as crystal structure. To investigate the CVD mechanism of both precursors in detail, temperature dependence of growth rate was also carried out, and we then obtained different activation energy of deposition to be 77.9 and 55.4 kJ/mol for TIP and BTDIP, respectively. Also, we are tested some TiO2 film synthesized with BTDIP precursor to apply dye-sensitized solar cell.

2012-10-01

 
 
 
 
141

Enhancement in the Sensing Properties of Methyl Orange Thin Film by TiO2 Nanoparticles  

Science.gov (United States)

This paper reports the enhancement in the sensing properties of organic dye methyl orange (MO) by introducing TiO2 nanoparticles. For this purpose, two surface type Ag/MO/Ag and Ag/MO:TiO2/Ag multifunctional sensors were fabricated by spin coating a 3.0 wt.% solution of MO and 3.0:0.3 wt.% of MO:TiO2 composite on pre-patterned silver (Ag) electrodes. The gap between Ag electrodes was 40 ?m. The Ag/MO/Ag and Ag/MO:TiO2/Ag structures were characterized to investigate their response towards humidity and temperature variations. The Ag/MO:TiO2/Ag sensor exhibited better sensitivity and response time than Ag/MO/Ag sensor. The large surface to volume ratio of TiO2 nanoparticles is the primary reason for the higher sensitivity of Ag/MO:TiO2/Ag sensor. The sensors can be used to detect humidity variations from 30% to 95% RH and temperature variation from 30°C to 200°C with good stability. Surface morphologies of the film were investigated by scanning electron microscope (SEM).

Tahir, Muhammad; Hassan Sayyad, Muhammad; Wahab, Fazal; Ahmad Khalid, Fazal; Aziz, Fakhra; Naeem, Shazia; Naeem Khalid, Muhammad

2014-12-01

142

Oxygen vacancy induced phase formation and room temperature ferromagnetism in undoped and Co-doped TiO2 thin films  

International Nuclear Information System (INIS)

TiO2 and Co-doped TiO2 (CTO) thin films deposited at various oxygen partial pressures by pulsed laser deposition exhibit room temperature ferromagnetism (RTFM) independent of their phase. Films deposited at 0.1 mTorr oxygen partial pressure show a complete rutile phase confirmed from glancing angle x-ray diffraction and Raman spectroscopy. At the highest oxygen partial pressure, i.e. 300 mTorr, although the TiO2 film shows a complete anatase phase, a small peak corresponding to the rutile phase along with the anatase phase is identified in the case of CTO film. An increase in O to Ti/(Ti+Co) ratio with increase in oxygen partial pressure is observed from Rutherford backscattering spectroscopy. It is revealed from x-ray photoelectron spectroscopy (XPS) that oxygen vacancies are found to be higher in the CTO film than TiO2, while the valency of cobalt remains in the +2 state. Therefore, the CTO film deposited at 300 mTorr does not show a complete anatase phase unlike the TiO2 film deposited at the same partial pressure. We conclude that RTFM in both films is not due to impurities/contaminants, as confirmed from XPS depth profiling and cross-sectional transmission electron microscopy (TEM), but due to oxygen vacancies. The magnitude of moment, however, depends not only on the phase of TiO2 but also on the crystallinity of the films. (paper)

2012-08-15

143

Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition  

International Nuclear Information System (INIS)

Nitrogen-doped titanium dioxide (TiO2) thin films were grown on (001) SiO2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (? = 248 nm, ?FWHM ? 10 ns, ? = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO2. The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

2010-12-01

144

Change in photoluminescence from Er-doped TiO2 thin films induced by optically assisted reduction  

International Nuclear Information System (INIS)

Erbium-doped TiO2 (TiO2:Er) thin films with the anatase structure have been prepared on Si substrate by laser ablation. Sharp and intense Er-related emission in the visible region as well as in the IR region has been observed under over-band-gap excitation. The broad photoluminescence (PL) peaking at about 530 nm newly appears at low temperature. It has been understood that the broad PL is induced by an optically assisted reduction effect that is caused by both the H2O adsorption and the reduction process of TiO2 to Ti2O3 by UV illumination. In the IR region, Er-related emission consisted of one main peak located at 1.534 ?m and many subpeaks located at around 1.54 ?m can be observed even at room temperature. The drastic thermal quenching of the Er-related 1.54 ?m emission is also considered due to the optically assisted reduction effect

2002-12-16

145

Photocatalytic activity of Al2O3-doped TiO2 thin films activated with visible light on the bacteria Escherichia coli  

International Nuclear Information System (INIS)

Al2O3-doped TiO2 thin films were prepared by combining electrophoretic deposition (EPD) with sputtering. A Corning* glass was used as a substrate, in which a titanium film was deposited by sputtering. Then, a precursor sol was prepared with Ti(n-OBu)4 and Al(s-OBu)3 and used as the medium for EPD. Next, the thin films were sintered and, finally, characterised by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Several cultures of Escherichia coli, strain XL1-Blue, were prepared. Nine experiments were carried out. In three of them, an inoculum (a low amount of a product that contains bacteria) was prepared without a film; in the other six Al2O3-doped TiO2 film-coated glass substrates were irradiated with visible light before they were introduced in the inoculum. The SEM and EDS results showed that TiO2-Al2O3 films were obtained, covering all the glass substrate and with uniform size of particles forming them, and that the aluminium was distributed uniformly on the film. XRD results showed that rutile phase was obtained. By TEM, the structure of TiO2 was demonstrated. Al2O3-doped TiO2 thin films were successful at eliminating E. coli.

2010-10-25

146

Properties of Sn-doped TiO2 nanotubes fabricated by anodization of co-sputtered Ti–Sn thin films  

International Nuclear Information System (INIS)

Self-organized Sn-doped TiO2 nanotubes (nts) were fabricated for the first time, by anodization of co-sputtered Ti and Sn thin films. This nanostructured material was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, UV–vis spectroscopy and transmission electron microscopy. Due to their remarkable properties, Sn-doped TiO2nts can find potential applications in Li-ion microbatteries, photovoltaics, and catalysis. Particularly, the electrochemical performance as an anode material for Li-ion microbatteries was evaluated in Li test cells. With current density of 70 ?A cm?2 (1 C) and cut-off potential of 1 V, Sn-doped TiO2nts showed improved performance compared to simple TiO2nts, and differential capacity plots revealed that the material undergoes full electrochemical reaction as a Rutile-type TiO2.

2012-02-15

147

Photocatalytically active TiO2 thin films produced by surfactant-assisted sol-gel processing  

International Nuclear Information System (INIS)

Thin TiO2 films were prepared from a titanium isopropoxide precursor by sol-gel processing with or without various nonionic surfactant molecules (Brij 56, Triton X-100 or Pluronic F-127). The photocatalytic efficiency of the transparent films obtained by a dip-coating technique was found to depend strongly on the use of and type of surfactant added. Titania/Pluronic sols resulted in homogeneous and crack-free TiO2 anatase films with a thickness as much as 300 nm after one dipping and heat-treatment (500 deg. C) cycle. Optical properties of the films were characterized by UV-Vis spectroscopy and crystalline structures by X-ray diffraction. A surfactant-assisted sol-gel process retarded crystallization of the anatase titania films, which resulted in smaller grain sizes (down to 10 nm) and presumably a larger active surface area. The morphology of the film surfaces as obtained by SEM techniques could be also correlated with the results of our photodegradation studies. The photocatalytic activity of the films was enhanced by first coating the glass substrate with a SiO2 protective layer prior to the deposition of the titania film. For our in situ studies of photodegradation we chose the monoazo dye Plasmocorinth B as a model compound as it is stable under environmental conditions and its degradation products are not coloured. The highest photobleaching rate was found for films deposited from the sol with addition of the Pluronic surfactant and it was almost twice as high as that for films deposited from sols without the surfactant

2006-01-20

148

Preparation, Structure and Properties of VOx and TiO2 Thin Films by MOCVD.  

Science.gov (United States)

Titanium and vanadium oxide thin films have been prepared in a cold wall low pressure MOCVD system for the study of MOCVD processing of epitaxial oxide films. Films were deposited on Si(111) and sapphire (0001) and (1120) at temperatures from 400 to 800(d...

H. L. M. Chang J. C. Parker H. You J. J. Xu D. J. Lam

1989-01-01

149

Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium  

Science.gov (United States)

We have investigated the structural and band alignment properties of nanoscale titanium dioxide (TiO2) thin films deposited on epitaxial crystallographic oriented Ge layers grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy. The TiO2 thin films deposited at low temperature by physical vapor deposition were found to be amorphous in nature, and high-resolution transmission electron microscopy confirmed a sharp heterointerface between the TiO2 thin film and the epitaxially grown Ge with no traceable interfacial layer. A comprehensive assessment on the effect of substrate orientation on the band alignment at the TiO2/Ge heterointerface is presented by utilizing x-ray photoelectron spectroscopy and spectroscopic ellipsometry. A band-gap of 3.33 ± 0.02 eV was determined for the amorphous TiO2 thin film from the Tauc plot. Irrespective of the crystallographic orientation of the epitaxial Ge layer, a sufficient valence band-offset of greater than 2 eV was obtained at the TiO2/Ge heterointerface while the corresponding conduction band-offsets for the aforementioned TiO2/Ge system were found to be smaller than 1 eV. A comparative assessment on the effect of Ge substrate orientation revealed a valence band-offset relation of ?EV(100) > ?EV(111) > ?EV(110) and a conduction band-offset relation of ?EC(110) > ?EC(111) > ?EC(100). These band-offset parameters are of critical importance and will provide key insight for the design and performance analysis of TiO2 for potential high-? dielectric integration and for future metal-insulator-semiconductor contact applications with next generation of Ge based metal-oxide field-effect transistors.

Jain, N.; Zhu, Y.; Maurya, D.; Varghese, R.; Priya, S.; Hudait, M. K.

2014-01-01

150

Synthesis of TiO2(110) ultra-thin films on W(100) and their reactions with H2O  

Science.gov (United States)

We present a study of the growth and reactivity of ultra-thin films of TiO2 grown on W(100). Three approaches to film growth are investigated, each resulting in films that show order in low-energy diffraction (LEED) and a low level of non-stoichiometry in X-ray photoelectron spectroscopy (XPS). H2O is used as a probe of the reactivity of the films, with changes in the Ti 2p and O 1s core levels being monitored by XPS. Evidence for the dissociation of H2O on the TiO2(110) ultra-thin film surface is adduced. These results are discussed with reference to related studies on native TiO2(110).

Matharu, J.; Cabailh, G.; Thornton, G.

2013-10-01

151

Ab-initio calculations of the Optical band-gap of TiO2 thin films  

CERN Multimedia

Titanium dioxide has been extensively studied in recent decades for its important photocatalytic application in environmental purification. The search for a method to narrow the optical band-gap of TiO2 plays a key role for enhancing its photocatalytic application. The optical band gap of epitaxial rutile and anatase TiO2 thin films deposited by helicon magnetron sputtering on sapphire and on SrTiO3 substrates was correlated to the lattice constants estimated from HRTEM images and SAED. The optical band-gap of 3.03 eV for bulk-rutile increased for the thin films to 3.37 on sapphire. The band gap of 3.20 eV for bulk-anatase increases to 3.51 on SrTiO3. In order to interpret the optical band gap expansion for both phases, ab-initio calculations were performed using the Vienna ab-initio software. The calculations for rutile as well anatase show an almost linear increase of the band gap width with decreasing volume or increasing lattice constant a. The calculated band gap fits well with the experimental values. T...

Wunderlich, W; Tanemura, M; Tanemura, S; Jin, P; Kaneko, K; Terai, A; Nabatova-Gabin, N; Belkada, R; Wunderlich, Wilfried; Miao, Lei; Tanemura, Masaki; Tanemura, Sakae; Jin, Ping; Kaneko, Kenji; Terai, Asuka; Nabatova-Gabin, Nataliya; Belkada, Rachid

2004-01-01

152

Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2-Cu2O thin films.  

Science.gov (United States)

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO2-Cu2O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie-Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ?172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO2, the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. PMID:24857856

Aytug, Tolga; Bogorin, Daniela F; Paranthaman, Parans M; Mathis, John E; Simpson, John T; Christen, David K

2014-06-20

153

Synthesis and characterization of beta barium borate thin films obtained from the BaO-B2O3-TiO2 ternary system  

International Nuclear Information System (INIS)

This work reports on the synthesis and the structural and optical characterization of beta barium borate (?-BBO) thin films containing 4, 8 and 16 mol% of titanium oxide (TiO2) deposited on fused silica and silicon (0 0 1) substrates using the polymeric precursor method. The thin films were characterized by X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy techniques. The optical transmission spectra of the thin films were measured over a wavelength range of 800-200 nm. A decrease was observed in the band gap energy as the TiO2 content was raised to 16 mol%. Only the ?-BBO phase with a preferential orientation in the (0 0 l) direction was obtained in the sample containing 4 mol% of TiO2 and crystallized at 650 deg. C for 2 h

2004-06-15

154

Photocatalytic thin films containing TiO2:N nanopowders obtained by the layer-by-layer self-assembling method  

International Nuclear Information System (INIS)

In this work, TiO2-N powders were synthesized by high-energy ball milling, using commercial titanium dioxide (TiO2) in the anatase phase and urea to introduce nitrogen into TiO2 in order to enhance their photocatalytic properties in the visible spectral region. Several samples were prepared by milling a mixture of TiO2-urea during 2, 4, 8, 12 and 24 h and characterized by spectroscopic and analytical techniques. X-ray diffraction (XRD) results showed the coexistence of anatase and high-pressure srilankite TiO2 crystalline phases in the samples. Scanning electron microscopy (SEM) revealed that the grain size of the powder samples decreases to 200 nm at 24 h milling time. UV-Vis diffuse reflectance spectroscopic data showed a clear red-shift in the onset of light absorption from 387 to 469 nm as consequence of nitrogen doping in the samples. The photocatalytic activity of the TiO2-N samples was evaluated by methylene blue degradation under visible light irradiation. It was found that TiO2-N samples had higher photocatalytic activity than undoped TiO2 samples, which could be assigned to the effect of introducing N atoms and XPS results confirm it. Using polyethylenimine (PEI), transparent thin films of TiO2-N nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO2 and PEI after each dip cycle. The adsorption of both TiO2 and PEI showed a saturation dip time of 15 min.

2012-01-01

155

Characterization and hydrogen gas sensing properties of TiO2 thin films prepared by sol–gel method  

International Nuclear Information System (INIS)

Highlights: ? Preparation and characterization of hydrogen sensing TiO2 thin films by sol–gel method. ? The annealing effect on the structure, electrical, optical and sensing properties was studied. ? The best sensitivity show the films composed of rutile with grain size of ?100 nm. - Abstract: Thin films of titanium dioxide with thickness of about 150 nm were deposited by spin coating method on a sapphire substrate from a sol–gel and annealed at various temperatures (from 600 °C to 1000 °C). Structural, optical and hydrogen gas sensing properties of the films were investigated. The annealing temperatures from 600 to 800 °C led to anatase phase with grain size in the range of 14–28 nm. Further increase of the annealing temperature resulted in transformation to rutile phase with larger grain size of about 100–120 nm. The optical band gap tended to decrease with increasing annealing temperature. The estimated values of activation energy for charge transport were in the range of 0.6–1.0 eV for films annealed at temperatures from 600 °C to 800 °C and 0.37–0.38 eV for films annealed at 900 °C and 1000 °C. The films annealed at 900 °C and 1000 °C showed better hydrogen sensitivity, what can be at least partially caused by their higher surface roughness.

2012-10-15

156

Effect of spin polarization on the optical properties of Co-doped TiO2 thin films  

International Nuclear Information System (INIS)

A non-linear variation of bandgap energy with Co doping is observed in sputter deposited Co-doped TiO2 thin films. This peculiar behavior is explained on the basis of mechanical stress in the films together with spin polarization due to s,p-d exchange interaction between the localized Co 3d electrons and delocalized electrons. Quantitative analyses of mechanical stress and grain boundary barrier potential due to spin polarization are performed from the below bandgap absorption tail. Furthermore, anomalous variations in both the refractive indices and extinction coefficients with Co doping are noted and are explained on the basis of ab-initio calculations based on density functional theory.

2011-04-01

157

Andreev spectroscopy of CrO2 thin films on TiO2 and Al2O3  

Science.gov (United States)

Here we analyse the spectroscopic information gathered at a number of single CrO2/Pb interfaces. We examine thin films requiring additional interfacial layers to generate long-range spin triplet proximity effect superconductivity (CrO2/TiO2) or not (CrO2/Al2O3). We analyse the data using two theoretical models and explore the use of a parameter-free method to determine the agreement between the models and experimental observations, showing the necessary temperature range that would be required to make a definitive statement. The use of the excess current as a further tool to distinguish between models is also examined. The analysis of the spectra demonstrates that the temperature dependence of the normalised zero-bias conductance is independent of the substrate onto which the films are grown. This result has important implications for the engineering of interfaces required for the long-range spin triplet proximity effect.

Yates, K. A.; Anwar, M. S.; Aarts, J.; Conde, O.; Eschrig, M.; Löfwander, T.; Cohen, L. F.

2013-09-01

158

Photochromic and self-cleaning properties of TiO2-AgCl/TiO2-xCu thin film.  

Science.gov (United States)

The TiO2-AgCl/TiO2-xCu thin films were prepared by sol-gel method and dip coated on glass slide. The prepared films were synthesized at the temperature of 400 degrees C for 2 h with a heating rate of 10 degrees C/min. The microstructure and properties of synthesized TiO2-AgCl/TiO2-xCu thin films were characterized by X-ray diffraction, scanning electron microscopy, atomic forced microscope and UV-vis diffuse reflectance spectroscopy. Finally, the hydrophilic property was evaluated by means of contact angle of water droplet on the films. The results show all samples have film thickness in range of 400-500 nm and their surfaces are dense and strong with a large surface area according to the image of atomic forced microscope. It can be noted that TiO2-AgCl/TiO2-5Cu thin films exhibit the highest photochromic (or the lowest capability of light transmittance) at 250-400 nm. The TiO2-AgCl/TiO2-xCu thin films can block UV C, UV B and UV A rays and exhibit self-cleaning effect (small contact angle, 3.9 degrees ) under UV irradiation. PMID:23646658

Sangchay, Weerachai; Sikong, Lek; Kooptarnond, Kalayanee

2013-02-01

159

Chemical bath deposition of thin TiO2-anatase films for dielectric applications  

International Nuclear Information System (INIS)

Titania thin films were prepared on bare Si and Pt/Ti/SiO2/Si substrates by chemical bath deposition (CBD) from solutions of a titanium peroxo complex and subsequent calcinations at 350 and 700 deg. C, respectively. The CBD process allowed deposition on both uncoated and metal-coated Si substrates with the same deposition rate. Optimization of the annealing process yielded uniform and crack-free nanocrystalline anatase films. The influence of the film thickness, irradiation of visible light, measuring frequency, temperature and substrate on the dielectric properties will be discussed in the paper. Films with a final thickness of about 600 nm showed comparably high relative permittivity of 31.8 on silicon and of 52.7 on Pt/Ti/SiO2/Si substrates, respectively. The present route provides anatase thin films with higher dielectric constants than classical sol-gel routes and is therefore a promising candidate for potential applications in large scale integration

2008-09-01

160

RAPID COMMUNICATION: Fine structures of photoluminescence spectra of TiO2 thin films with the addition of ZnFe2O4  

Science.gov (United States)

The fine structures of low-temperature photoluminescence (PL) spectra of TiO2 thin films with addition of ZnFe2O4 (ZnFe2O4/TiO2 composite films) are firstly reported. The films were deposited on quartz substrates by radio-frequency magnetron sputtering method. It is shown that different phase structures are developed for the pure TiO2 and composite films at different annealing temperatures. There is a very strong broad PL band in the composite films, which consists of some minor peaks besides the main PL peak. It is considered that the main PL peak originates from the transition of the impurity-related centres and the minor peaks come from transition, assisted by phonon replicas, of impurity- and oxygen-related defects in TiO6 octahedra.

Li, Guanghai; Jin, Yunxia; Zhang, Yong; Zhang, Yunxia; Zhang, Lide

2002-06-01

 
 
 
 
161

Hydrophilicity and formation mechanism of large-pore mesoporous TiO2 thin films with tunable pore diameters  

International Nuclear Information System (INIS)

Using n-butanol released in situ as the cosurfactant, transparent large-pore mesoporous nanocrystalline anatase (meso-nc-TiO2) thin films with narrow pore size distribution have been successfully synthesized in a Ti(OBun)4-P123-EtOH-HCl system. Furthermore, the mesopore size can be easily controlled in the range of 8.3-14.0 nm through adjusting the quantities of Ti(OBun)4, corresponding to the amount of n-butanol released in situ. X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption were used to investigate the relationship between the amount of Ti(OBun)4 and the structural parameters of the obtained meso-nc-TiO2 thin films. A reasonable mechanism is also proposed here to explain the formation of large-pore mesoporous TiO2 with tunable pore diameters. The hydrophilicity of our obtained films was evaluated by water contact angle measurement in air. It was found that, in the absence of ultraviolet (UV) illumination, the presented transparent large-pore meso-nc-TiO2 thin films exhibit high hydrophilicity

2006-08-14

162

TiO2:polymer bulk-heterojunction thin films made from a miscible new carbazole based TiO2 precursor with poly(N-vinylcarbazole) for enhanced charge transfer properties  

International Nuclear Information System (INIS)

TiO2:polymer bulk-heterojunctions (BHJ) have been elaborated from hydrolysis-condensation reactions of a TiO2 precursor in contact to the surrounding air humidity in a polymer thin film. A new precursor: tetrakis(9H-carbazole-9-yl-ethyl-oxy) titanium [Ti(OeCarb)4], has been synthesized as a TiO2 precursor to form a blend with Poly(N-vinylcarbazole) (PVK) which is the archetype of non-conjugated photoconducting polymer with strong electron-donor properties. This new precursor is expected to enhance the materials miscibility because of the chemical structure of the ligand close to the PVK repetitive unit and to inhibit premature hydrolysis by a strong steric hindrance. Commercial titanium isopropoxide [Ti(iOPr)4] was used as a reference to study the influence of the chemical structure of the precursor on BHJ properties. Photoluminescence studies have shown charge transfer enhancement when Ti(OeCarb)4 is used. In order to understand this ligand effect, photoluminescence (PL) responses were correlated with surface chemical composition (XPS) and topography (AFM) of thin films. Results have shown that Ti(OeCarb)4 allows a better miscibility between TiO2 and PVK. The lower reactivity of Ti(OeCarb)4 to hydrolysis and its chemical structure close to the repetitive unit structure of the polymer are believed to play a main role in the BHJ property improvement

2009-05-15

163

Investigation of Inhomogeneity of TiO2 Thin Films Using Spectroscopic Ellipsometry  

International Nuclear Information System (INIS)

Titanium dioxide thin films have been deposited on silicon wafers (100) substrates by pulse DC reactive magnetron sputtering. The spectroscopic ellipsometry is the method use to determine the degree of inhomogeneity of titanium dioxide thin films. The effect of operating pressure on the micro-structural and optical properties of inhomogenity Titanium dioxide thin films were characterized by grazing-incidence X-ray diffraction, spectroscopic ellipsometry, field emission scanning electron microscope and high resolution transmission electron microscopy. The optical properties of the films were examined by variable-angle spectroscopic ellipsometer. Several spectroscopic ellipsometry models, categorized by physical models, were proposed based on the 'simpler better' rule and curve-fits, which were generated and compared to experimental data using regression analysis. It has been found that the triple-layer physical model with the Cody-Lorentz dispersion model offered the most convincing result. Titanium dioxide thin film was found inhomogeneous and a more detailed analysis of high resolution transmission electron microscopy and field emission scanning electron microscope are discussed.

2013-03-01

164

Preparation and photo-induced superhydrophilicity of composite TiO2-SiO2-In2O3 thin film  

International Nuclear Information System (INIS)

In this work, TiO2-SiO2-In2O3 composite thin films on glass substrates were prepared by the sol-gel dip coating process. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the structural and chemical properties of the films. UV-vis spectrophotometer was used to measure the transmittance spectra of thin films. The water contact angle (WCA) of thin films during UV/vis irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicated that fabrication of composite film has a significant effect on transmittance and superhydrophilicity of TiO2 films.

2010-09-15

165

Alternative to classic annealing treatments for fractally patterned TiO2 thin films  

Science.gov (United States)

Titanium dioxide thin films have been deposited by reactive magnetron sputtering on glass and subsequently irradiated by UV radiation using a KrF excimer laser. The influence of the laser fluence (F) on the constitution and microstructure of the deposited films is studied for 0.05fractally textured films presenting characteristics of high porosity and high specific surface area. Finally, contact angle analysis suggests hydrophobic or wetting behavior depending on F. In order to explain the laser-induced structuration mechanisms, we have successfully applied a fractal as well as the nucleation theories. We propose that electronics effects could be responsible for the observed crystallization.

van Overschelde, O.; Guisbiers, G.; Hamadi, F.; Hemberg, A.; Snyders, R.; Wautelet, M.

2008-11-01

166

Effect of sputtering pressure and post-annealing on hydrophilicity of TiO2 thin films deposited by reactive magnetron sputtering  

International Nuclear Information System (INIS)

A series of TiO2 thin films was deposited onto glass substrates without intentional heating or biasing by magnetron sputtering of a titanium target using Ar/O2 reactive mixtures over a broad range of total sputtering pressures from 0.12 Pa to 2.24 Pa. Each of the film types was deposited by the threshold poisoned mode at a specific given oxygen flow rate monitored in-situ by optical emission spectroscopy. Both the sputtering pressure and thermal annealing are the key factors for the TiO2 films to yield fast-response superhydrophilicity with a water contact angle of 5o. The mechanism of superhydrophilicity for the TiO2 films deposited by high-pressure sputtering will be discussed based on empirical studies of X-ray diffractometry, high-resolution scanning microscopy and atomic force spectroscopy.

2010-10-01

167

ZrO2-TiO2 thin films and resonators for mid-infrared integrated photonics  

Science.gov (United States)

Mid-infrared (MIR, 2-6 ?m wavelength) transparent metal oxides are attractive materials for planar integrated photonic devices for sensing applications. In this study, we present reactive sputtering deposited ZrO2-TiO2 (ZTO) thin films as a new material candidate for integrated MIR photonics. We demonstrate that amorphous ZTO thin films can be achieved with Ti concentration of 40 at.%. With increasing Ti concentration, the optical band gap decreases monotonically from 4.34 eV to 4.11 eV, while the index of refraction increases from 2.14 to 2.24 at 1 ?m wavelength. MIR micro-disk resonators on MgO substrates are demonstrated using Ge23/Sb7S70/Zr0.6Ti0.4O2 strip-loaded waveguides with a loaded quality factor of ~11,000 at 5.2 ?m wavelength. By comparing with a reference device of Ge23Sb7S70 resonator on MgO and simulating the optical confinement factors, the ZTO thin film loss is estimated to be below 10 dB/cm. Single mode shallow ridge waveguides with a ridge height of 400 nm and a slab height of 1.7 ?m are also demonstrated using ZrO2 thin films on MgO substrates. The low loss, relatively high index of refraction, superior stability and proven CMOS compatibility of ZTO thin films make them highly attractive for MIR integrated photonics.

Jiang, Feipeng; Duan, Ningyuan; Lin, Hongtao; Li, Lan; Hu, Juejun; Bi, Lei; Lu, Haipeng; Weng, Xiaolong; Xie, Jianliang; Deng, Longjiang

2014-03-01

168

Modifications in structural and electronic properties of TiO2 thin films using swift heavy ion irradiation  

International Nuclear Information System (INIS)

We report on the structural and electronic properties of swift heavy ion (SHI) irradiated pristine TiO2 thin films, deposited by radio frequency magnetron sputtering on sapphire substrates. The high resolution x-ray diffraction and Raman measurements show a structural phase transition from anatase to admixture of brookite and rutile phases of TiO2 with increasing SHI fluence followed by a significant distortion in the TiO6 octahedra. The modification in the electronic structure stimulated by SHI irradiation has been investigated using x-ray absorption (XAS) experiments at the O K and Ti L3,2 absorption edges. The O K edge spectra clearly indicate the splitting of the pre-edge spectral features having t2g and eg symmetry bands due to structural disorder/distortion induced by irradiation. The intensity of the SHI generated components at the O K edge increases monotonically, which can be correlated to the modification in unoccupancies associated with O 2 p orbitals hybridized with Ti 3 d states. The XAS spectra at the Ti L3,2 edge further authenticate that SHI creates a controlled structural disorder/distortion in the TiO6 octahedra.

2011-10-15

169

Influences of the iron ion (Fe3+)-doping on structural and optical properties of nanocrystalline TiO2 thin films prepared by sol-gel spin coating  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films doping of various iron ion (Fe3+) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 deg. C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO2 thin films comprised only the anatase TiO2, but the crystallinity decreased when the Fe3+ content increased from 0% to 20%. During the Fe3+ addition to 20%, the phase of TiO2 thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (Eg) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe3+ content.

2011-10-01

170

Influences of the iron ion (Fe 3+)-doping on structural and optical properties of nanocrystalline TiO 2 thin films prepared by sol-gel spin coating  

Science.gov (United States)

Titanium dioxide (TiO 2) thin films doping of various iron ion (Fe 3+) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 °C. The structure, surface morphology and optical properties, as a function of the doping, have been studied by X-ray diffractometer (XRD), Raman, ultraviolet-visible (UV-vis) and Spectroscopic Ellipsometry (SE). XRD and Raman analyzes of our thin films show that the crystalline phase of TiO 2 thin films comprised only the anatase TiO 2, but the crystallinity decreased when the Fe 3+ content increased from 0% to 20%. During the Fe 3+ addition to 20%, the phase of TiO 2 thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap ( Eg) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe 3+ content.

Naceur, J. Ben; Mechiakh, R.; Bousbih, F.; Chtourou, R.

2011-10-01

171

Correlation between structure and semiconductor-to-metal transition characteristics of VO2/TiO2/sapphire thin film heterostructures  

International Nuclear Information System (INIS)

This study focuses on the role of strain and thin film epitaxy on the semiconductor-to-metal transition (SMT) characteristics of single crystalline VO2 thin films. The VO2/TiO2 heterostructures of controlled orientations were epitaxially grown on m-cut, r-cut and c-cut sapphire substrates. Detailed structural investigations were performed using high-resolution X-ray diffraction (2?–? and ? scans) and high-resolution transmission electron microscopy techniques to correlate SMT properties with microstructural characteristics. Monoclinic (M1) VO2 thin films with (1 0 0), (0 0 1) and (2¯01) out-of-plane orientations were grown on TiO2(1 0 1)/r-sapphire, TiO2(1 0 0)/c-sapphire and TiO2(0 0 1)/m-sapphire platforms, respectively. The in-plane alignments across the interfaces were established to be [0 1 0](1 0 0)VO2||[0 1 0](1 0 1)TiO2, [1 0 0](0 0 1)VO2||[0 0 1](1 0 0)TiO2 and [010](2¯01)VO2?[010](001)TiO2 for r-sapphire, c-sapphire and m-sapphire substrates, respectively. We were able to tune the SMT temperature of VO2 epilayers from ?313 K to 354 K (bulk Tc ? 340 K). The SMT characteristics were interpreted based upon the residual strain in the VO2 lattice, particularly along the c-axis of tetragonal VO2. This research introduces the VO2-based single crystalline heterostructures as a potential candidate for a wide range of applications where different transition temperatures are required

2013-12-01

172

Quantum size effects in TiO2 thin films grown by atomic layer deposition.  

Science.gov (United States)

We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier transport and separation, and increase the efficiency of energy conversion systems. PMID:24605275

Tallarida, Massimo; Das, Chittaranjan; Schmeisser, Dieter

2014-01-01

173

Molecular Interaction of Thin Film Photosensitive Organic Dyes on TiO2 Surfaces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The photosensitive molecule adsorption on titanium dioxide (TiO2) forms the so-called “dye sensitized TiO2” system, a typical organic/oxide heterojunction, which is of great interest in catalysis and energy applications, e.g. dye-sensitized solar cell (DSSC). Traditionally, the transition metal complex dyes are the focus of the study. However, as the fast development of the organic semiconductors and invention of new pure organic dyes, it is necessary to expand the research horizon to cov...

Yu, Shun

2011-01-01

174

Effect of solution contents on the evolution of microstructure and photoluminescence of laser-annealed rutile TiO2 thin films  

International Nuclear Information System (INIS)

Highlights: •The titanium dioxide (TiO2) material has attracted great attentions to wide applications. •The microstructure and photoluminescence (PL) of TiO2 are related to annealing methods. •The laser-annealed rutile TiO2 films were prepared using various sol gel solutions. •The tetraisopropyl orthotitanate content is the primary factor affecting rutile formation. •The PL emission of our rutile TiO2 can be extended from ultraviolet to visible range due to residual organics. -- Abstract: The titanium dioxide (TiO2) material has attracted great attentions because of its wide application in photocatalyst and optoelectronics devices. The microstructure and photoluminescence behavior of TiO2 thin films are related to the fabrication and annealing methods. In this article, the amorphous titanium oxide thin films were prepared by sol gel process with a mixture of tetraisopropyl orthotitanate, acetonylacetone, distilled water and alcohol at various molar ratios and then spin-coated on the p-Si(1 0 0) substrate. Subsequently, the CO2 laser irradiation at a power of 1.5 W was utilized for annealing treatment to form crystalline rutile TiO2 instead of conventional furnace annealing. The evolution of microstructure, bonding and photoluminescence (PL) of TiO2 films were characterized by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy, Fourier transform infrared spectrometer and PL spectrometer. GIXRD showed that the crystalline phase of TiO2 after 1.5 W laser annealing was rutile. The PL spectra of annealed films covered broad wavelengths of 350–800 nm which extends conventional ultraviolet range. They can be deconvoluted into three peaks at about 411, 441 and 534 nm which were attributed to the lattice emission, deep-level emissions from oxygen vacancies and defect states from bonding of extra impurities of Ti, O and C in rutile TiO2 together with residual organics. The relationship between the process parameters, microstructure, bonding and PL behavior were further discussed and established

2013-10-15

175

The photocatalytic application and regeneration of anatase thin films with embedded commercial TiO2 particles deposited on glass microrods  

International Nuclear Information System (INIS)

Anatase thin films (2 were prepared by sol-gel method. TiO2-anatase thin films were deposited on a fiberglass substrate and then ground to obtain glass microrods containing the composite films. The film structure was characterized using Raman spectroscopy, atomic absorption and UV-vis spectrophotometry, and atomic force microscopy. The photocatalytic activity of the composite films, calcined at 450 deg. C, and the regeneration of the activity under the same experimental conditions, were assessed using gas chromatography to study the photodegradation of phenol, an industrial pollutant, in water under 365 nm irradiation. The film with 15.0 wt.% of P25 TiO2 was found to be more photoactive (54 ppm of degraded phenol at 6 h of illumination) than the other ones

2006-03-15

176

Photo(electro)catalytic Activity of Cu2+-Modified TiO2 Nanorod Array Thin Films under Visible Light Irradiation  

Science.gov (United States)

In the present study, a two-step method was applied to synthesise Cu2+-modified TiO2 nanorod array thin films for photocatalytic processes. TiO2 nanorod array thin films were synthesised by a hydrothermal method and then modified with an ultrasonic-assisted sequential cation adsorption method. The samples were characterised by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy and inductively coupled plasma mass spectroscopy (ICP-MS) analysis. The photoelectrochemical properties of the samples were evaluated by linear sweep voltammetry and Mott-Schottky analysis; photocatalytic activities were tested by methylene blue degradation under visible light. The photocurrent density of the TiO2/FTO sample modified with 50 mM Cu2+ solution was 26 times higher than that of the unmodified TiO2/FTO sample. Additionally, methylene blue degradation efficiency under visible light was increased 40% with respect to the efficiency of the unmodified sample. The mechanism of the photocatalytic activity enhancement of Cu2+-modified TiO2 nanorod films was discussed.

Kerkez, Özge; Boz, ?smail

2014-05-01

177

Fabrication and Characterization of Hydrophilic TiO2 Thin Films on Unheated Substrates Prepared by Pulsed DC Reactive Magnetron Sputtering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

TiO2 thin films were deposited on unheated silicon wafers (100) and glass slides by a pulsed DC reactive magnetron sputtering in an ultrahigh vacuum (UHV) system. The effects of both an operating pressure and deposition time on film structure, surface morphology, and optical property were studied. The film structure and microstructure were characterized by grazing-incidence X-ray diffraction (GIXRD) technique and transmission electron microscopy (TEM). The surface morphology was investigated ...

Horprathum, M.; Chindaudom, P.; Limnonthakul, P.; Eiamchai, P.; Nuntawong, N.; Patthanasettakul, V.; Pokaipisit, A.; Limsuwan, P.

2010-01-01

178

An in-situ real-time optical fiber sensor based on surface plasmon resonance for monitoring the growth of TiO2 thin films.  

Science.gov (United States)

An optical fiber sensor based on surface plasmon resonance (SPR) is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings. PMID:23881144

Tsao, Yu-Chia; Tsai, Woo-Hu; Shih, Wen-Ching; Wu, Mu-Shiang

2013-01-01

179

An In-situ Real-Time Optical Fiber Sensor Based on Surface Plasmon Resonance for Monitoring the Growth of TiO2 Thin Films  

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Full Text Available An optical fiber sensor based on surface plasmon resonance (SPR is proposed for monitoring the thickness of deposited nano-thin films. A side-polished multimode SPR optical fiber sensor with an 850 nm-LD is used as the transducing element for real-time monitoring of the deposited TiO2 thin films. The SPR optical fiber sensor was installed in the TiO2 sputtering system in order to measure the thickness of the deposited sample during TiO2 deposition. The SPR response declined in real-time in relation to the growth of the thickness of the TiO2 thin film. Our results show the same trend of the SPR response in real-time and in spectra taken before and after deposition. The SPR transmitted intensity changes by approximately 18.76% corresponding to 50 nm of deposited TiO2 thin film. We have shown that optical fiber sensors utilizing SPR have the potential for real-time monitoring of the SPR technology of nanometer film thickness. The compact size of the SPR fiber sensor enables it to be positioned inside the deposition chamber, and it could thus measure the film thickness directly in real-time. This technology also has potential application for monitoring the deposition of other materials. Moreover, in-situ real-time SPR optical fiber sensor technology is in inexpensive, disposable technique that has anti-interference properties, and the potential to enable on-line monitoring and monitoring of organic coatings.

Wen-Ching Shih

2013-07-01

180

Reactive sputtering deposition of photocatalytic TiO2 thin films on glass substrates  

International Nuclear Information System (INIS)

Titania polycrystalline thin films with high photocatalytic activity were produced by dc reactive magnetron sputtering. X-ray diffraction experiments revealed that the as-deposited films are amorphous and thus unable to deliver an optimum photocatalytic efficiency. By annealing the deposited coatings for 2 h at 500 deg. C a competitive crystallographic phase growth of anatase and rutile was observed. The anatase titania developed a very high photocatalytic activity. When immersed in a rhodamine B solution and irradiated with ultra-violet light for different periods of time, one could monitor the degradation rate of the dye concentration with time from the decay of its absorption spectra. Several deposition parameters dictate the optimum performance of the titania coatings, such as their relative oxygen and argon partial pressure, cathode current, bias voltage, external magnetic field and post-annealing temperature

2007-03-25

 
 
 
 
181

PVD-Grown photocatalytic TiO2 thin films on PVDF substrates for sensors and actuators applications  

International Nuclear Information System (INIS)

Titanium dioxide's self-cleaning effect has been broadly used in textiles, paints, windows, residual water treatment, amongst various other photocatalytic applications. Polymer substrates have found their way in the semiconductor industry as a base layer for flexible electronics, as well as in sensor and actuator applications. The optimum performance of these systems may be affected by dirt adsorbed on its surface, which can also originate mechanisms for the degradation of the polymer. These thin films have been deposited on electroactive poly(vinilidene fluoride) - PVDF - polymer substrates by unbalanced reactive magnetron sputtering. Rutherford Backscattering experiments evidenced that these coatings have a TiO2 stoichiometry. Raman spectroscopy experiments revealed that the as-deposited coatings on polymer substrates are mostly amorphous, however evidence of anatase and rutile nano-crystalline phases can be found. The photocatalytic behavior of the titanium dioxide coatings was determined by combined ultra-violet irradiation and absorption measurements of a particular dye in the presence of the catalyst. In order to assess the mechanical behavior of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. The stress-strain curves were analyzed and correlated with photocatalytic efficiency along these curves, as well as with the structural data

2008-12-01

182

Fabrication and characterization of metal/insulator/semiconductor structures based on TiO2 and TiO2/SiO2 thin films prepared by low-temperature arc vapor deposition  

Science.gov (United States)

The present work involves the fabrication and characterization of two different metal/insulator/semiconductor (MIS) structures: Pd/TiO2/Si and Pd/TiO2/SiO2/Si. The TiO2 thin films on the n-type Si substrate were deposited using low-temperature arc vapor deposition process. The electrical characterizations of MIS structures were investigated using capacitance-voltage and current density-voltage measurements. The effects of annealing on the properties of the films were also studied. Furthermore, the structural, surface morphological, and electrical properties of the devices were compared with those obtained using other deposition techniques.

Shubham, Kumar; Chakrabarti, P.

2014-05-01

183

TiO2 nanotubes manufactured by anodization of Ti thin films for on-chip Li-ion 2D microbatteries  

International Nuclear Information System (INIS)

The use of self-organized TiO2 nanotube arrays electrochemically grown onto Si is investigated for the fabrication of an alternative electrode dedicated to on-chip Li-ion 2D microbatteries. Discharge/charge curves and cycling performance are studied in lithium-anode electrochemical test cells for both amorphous and crystalline titania nanotubes. At 5 ?A cm-2 amorphous TiO2 nanotube layers onto Si deliver a maximum areal capacity of 89 ?Ah cm-2 in the first reversible discharge and 56 ?Ah cm-2 over 50 cycles. We demonstrate that these nanostructured thin film electrodes showing such electrochemical performances are compatible with IC technology.

2009-07-01

184

Photocatalytic activity of Pd-Doped TiO2 thin films by using a RF magnetron Co-sputtering method  

International Nuclear Information System (INIS)

Pd/TiO2 thin films on quartz glass were prepared by using a RF magnetron co-sputtering process, and the calcination effects on their physical and chemical properties were investigated. The films were in the anatase phase at 300 - 600 .deg. C and the rutile phase at 900 .deg. C. The crystallite sizes of Pd/TiO2 thin films were slightly larger than those of the TiO2 thin films. The secondary particle sizes of Pd/TiO2 thin films at 600 .deg. C were about 20 - 60 nm, and the secondary particles were more uniform and less agglomerated. The deposited films calcined at 300 - 600 .deg. C had high transparency in the visible range. The transmittances of the films calcined at 900 .deg. C were significantly reduced in the wavelength range of 300 - 800 nm due to the absorption and the scattering of light resulting from agglomerates of the primary particles. The Pd/TiO2 thin films showed better photocatalytic activity than the TiO2 thin films.

2005-10-01

185

Optical-Refractometric Synthesis of Transmission Spectra and Optical Parameters of 0.5TiO2*0.5Nd2O3 Thin Films  

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Full Text Available An original method for determining the optical parameters of thin films with the optical-refractometric synthesis of their transmission spectra is suggested. The proper choice of dispersion relation for refractive indices is substantiated. Experimental studies and computer simulations are performed for the quartz-glass optical element with 0.5TiO2*0.5Nd2O3 film. The advantages of the suggested method are discussed.

I.P. Studenyak

2003-09-01

186

Evolution of structural and optical properties of rutile TiO2 thin films synthesized at room temperature by chemical bath deposition method  

Science.gov (United States)

Nanocrystalline thin films of TiO2 were prepared on glass substrates from an aqueous solution of TiCl3 and NH4OH at room temperature using the simple and cost-effective chemical bath deposition (CBD) method. The influence of deposition time on structural, morphological and optical properties was systematically investigated. TiO2 transition from a mixed anatase-rutile phase to a pure rutile phase was revealed by low-angle XRD and Raman spectroscopy. Rutile phase formation was confirmed by FTIR spectroscopy. Scanning electron micrographs revealed that the multigrain structure of as-deposited TiO2 thin films was completely converted into semi-spherical nanoparticles. Optical studies showed that rutile thin films had a high absorption coefficient and a direct bandgap. The optical bandgap decreased slightly (3.29-3.07 eV) with increasing deposition time. The ease of deposition of rutile thin films at low temperature is useful for the fabrication of extremely thin absorber (ETA) solar cells, dye-sensitized solar cells, and gas sensors.

Mayabadi, A. H.; Waman, V. S.; Kamble, M. M.; Ghosh, S. S.; Gabhale, B. B.; Rondiya, S. R.; Rokade, A. V.; Khadtare, S. S.; Sathe, V. G.; Pathan, H. M.; Gosavi, S. W.; Jadkar, S. R.

2014-02-01

187

Effects Of Tin Doping On Ethanol And Isopropyl Alcohol Sensing Properties Of Sol-Gel Derived TiO2 Thin Films  

International Nuclear Information System (INIS)

In this work, ethanol and isopropyl alcohol sensing properties of Sn-doped TiO2 thin films were investigated. Sn-doped titanium dioxide (TiO2) films were prepared by sol-gel dipping technique using titanium (IV) n-butoxide and tin (IV) chloride pentahydrate as starting materials. The starting materials were dissolved in ethanol separately. Mixture of the solutions was stirred for 1 h. Sn-doped and undoped TiO2 thin films were deposited onto glass substrate patterned with interdigitated electrodes (IDT) by a sol-gel dipping process. Final curing were performed at 820 K in air for 2 h. The structure of the films was studied by X-ray diffraction. Sn:Ti ratio (wt.) was kept between the values of 5% and 11%. Response characteristics of the films were determined in the gas concentrations range of 10%-30%. Gas concentrations were controlled by mass flow controller. Gas sensing characteristics were obtained by recording the current values of the films versus time as a function of gas concentration at the temperatures of 300 and 525 K. The results showed that sensitivity of the films increases with increasing tin doping. We can conclude that tin doping to SnO2 films improve the sensing parameters.

2009-09-24

188

Structural and dielectric properties of TiO2 thin films deposited by the sol-gel method on Si substrates  

Science.gov (United States)

Titanium dioxide thin films with good dielectric properties were obtained on Si substrates using the sol-gel method. The metal oxide films were deposited by spin coating from sol solution and additionally annealed at 600 °C and 850 °C. XRD analysis, FTIR and Raman spectroscopy were used for revealing the film structure, the crystal phases and the formation of a polycrystalline material. The electrical measurements on metal-insulator-silicon (MIS) structures showed good dielectric properties. An optimal regime for high temperature annealing (850°C/15 min) was found, for which no effects related to the thermal instability of TiO2 film on Si were observed. The leakage current density of a 38-nm thick TiO2 film annealed at 850°C/15 min/O2 was approximately 1.95×10-9 A/cm2 at 1.6×10-6 V/cm.

Vitanov, P.; Harizanova, A.; Ivanova, T.

2012-03-01

189

Co distribution in ferromagnetic rutile Co-doped TiO$_2$ thin films grown by laser ablation on silicon substrates  

CERN Document Server

Pure rutile Co-doped TiO$_2$ films were fabricated successfully by the conventional pulsed laser deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the synthesized target, and films under various conditions all are ferromagnetic well above room temperature. Even though Rutherford backscattering spectroscopy measurements show that Co atoms seem to be mostly localized near the surface of the films and less exist in deeper levels, other experimental evidences show that the ferromagnetism does not come from Co segregations but from the Co-doped TiO$_2$ matrix. Rutile Ti$_1-x$Co$_x$O$_2$ thin films grown by a very simple technique on low-price silicon substrates showing Curie temperature (TC) above 400 K appear to be very attractive to applications.

Hong, N H; Prellier, W; Hassini, A; Hong, Nguyen Hoa; Sakai, Joe; Hassini, Awatef

2003-01-01

190

Co distribution in ferromagnetic rutile Co-doped TiO2 thin films grown by laser ablation on silicon substrates  

International Nuclear Information System (INIS)

Pure rutile Co-doped TiO2 films were fabricated by the pulsed-laser-deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the target, and films under various conditions all are ferromagnetic well above room temperature. Even though Rutherford backscattering spectroscopy measurements show that Co atoms mostly localize near the surface of the films and exist less in deeper levels, other experimental evidence shows that the ferromagnetism does not come from Co segregations, but from the Co-doped TiO2 matrix. Rutile Ti1-xCoxO2 thin films grown by a very simple technique on low-cost silicon substrates showing a Curie temperature (TC) above 400 K appear to be very attractive to applications

2003-10-13

191

Light-emitting diode applications of colloidal CdSe/ZnS quantum dots embedded in TiO2-? thin film  

International Nuclear Information System (INIS)

We report the light-emitting diode (LED) characteristics of colloidal core-shell CdSe/ZnS nanocrystal quantum dots (QDs) embedded in TiO2-? thin films on Si substrate. High-quality CdSe/ZnS QDs were synthesized via a pyrolysis in the range of 220-280 C. The QDs were embedded in TiO2-? thin film at 200 C by plasma-enhanced metallorganic chemical vapor deposition. The diode structure of n-TiO2-?/QDs/p-Si showed electroluminescence characteristics, indicating the possibility of LED applications of colloidal CdSe/ZnS nanocrystal QDs embedded in oxide films on large-area Si wafer. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

2009-04-01

192

Nanostructured columnar heterostructures of TiO2 and Cu2O enabled by a thin-film self-assembly approach: Potential for photovoltaics  

International Nuclear Information System (INIS)

Graphical abstract: Display Omitted Highlights: ? Material self-assembly in phase-separated oxides is exploited. ? Three-dimensionally nanostructured epitaxial films are grown using sputtering. ? Films are composed of well-ordered oriented nanopillars of n-type TiO2 and p-type Cu2O. ? Observed interfaces at adjacent TiO2–Cu2O columns are nearly atomically distinct. ? Absorption profile of the composite film captures a wide range of the solar spectrum. -- Abstract: Significant efforts are being devoted to the development of multifunctional thin-film heterostructures and nanostructured material architectures for components with novel applications of superconductivity, multiferroicity, solar photocatalysis and energy conversion. In particular, nanostructured assemblies with well-defined geometrical shapes have emerged as possible high efficiency and economically viable alternatives to planar photovoltaic thin-film architectures. By exploiting phase-separated self-assembly, here we present advances in a vertically oriented two-component system that offers potential for future development of nanostructured thin film solar cells. Through a single-step deposition by magnetron sputtering, we demonstrate growth of an epitaxial, composite film matrix formed as self-assembled, well ordered, phase segregated, and oriented nanopillars of n-type TiO2 and p-type Cu2O. The composite films were structurally characterized to atomic resolution by a variety of analytical tools, and evaluated for preliminary optical properties using absorption measurements. We find nearly atomically distinct TiO2–Cu2O interfaces (i.e., needed for possible active p–n junctions), and an absorption profile that captures a wide range of the solar spectrum extending from ultraviolet to visible wavelengths. This high-quality materials system could lead to photovoltaic devices that can be optimized for both incident light absorption and carrier collection.

2013-02-01

193

Controlling the Al-Doping Profile and Accompanying Electrical Properties of Rutile-Phased TiO2 Thin Films.  

Science.gov (United States)

The role of Al dopant in rutile-phased TiO2 films in the evaluation of the mechanism of leakage current reduction in Al-doped TiO2 (ATO) was studied in detail. The leakage current of the ATO film was strongly affected by the Al concentration at the interface between the ATO film and the RuO2 electrode. The conduction band offset of the interface increased with the increase in the Al dopant concentration in the rutile TiO2, which reduced the leakage current in the voltage region pertinent to the next-generation dynamic random access memory application. However, the Al doping in the anatase TiO2 did not notably increase the conduction band offset even with a higher Al concentration. The detailed analyses of the leakage conduction mechanism based on the quantum mechanical transfer-matrix method showed that Schottky emission and Fowler-Nordheim tunneling was the dominant leakage conduction mechanism in the lower and higher voltage regions, respectively. The chemical analyses using X-ray photoelectron spectroscopy corroborated the electrical test results. PMID:24749990

Jeon, Woojin; Rha, Sang Ho; Lee, Woongkyu; Yoo, Yeon Woo; An, Cheol Hyun; Jung, Kwang Hwan; Kim, Seong Keun; Hwang, Cheol Seong

2014-05-28

194

Photooxidation of dibenzothiophene on TiO(2)/hectorite thin films layered catalyst.  

Science.gov (United States)

A new titanium(IV) oxide-hectorite nanofilm photocatalyst was prepared on quartz slides. It was evaluated in the photooxidation of dibenzothiophene (DBT) in nonpolar organic solution (tetradecane), as a model for diesel fuel. A removal regimen was developed consisting of catalytic photooxidation followed by adsorption of products on silica gel. Photooxidation of DBT was performed with and without catalyst, at 254 and 300 nm. Comparison was made with a commercially available TiO(2) catalyst, Degussa P25. The catalyst was analyzed by nitrogen adsorption, XRD, SEM, and TGA-DTA. DBT concentrations were measured by HPLC and UV spectrophotometry. Preliminary qualititative analysis of products was performed by UV and HPLC. Results indicated that the outlined process was effective in reducing sulfur levels to below 10 ppm sulfur. PMID:16600276

Robertson, Jamie; Bandosz, Teresa J

2006-07-01

195

Study on the Electrical and Thermal Conductivity of Ordered Mesoporous TiO2 Thin Film Incorporated with Pt Nanoparticles  

Science.gov (United States)

Ordered mesoporous TiO2 films with incorporated Pt nanoparticles were prepared using titanium tetraisopropoxide, hexachloroplatinic acid hexahydrate, and Pluronic P-123 as a titania precursor, a Pt precursor, and a structure-directing agent, respectively. Pt nanoparticles were introduced to enhance the electrical properties of the mesoporous films, which have excellent thermal insulation properties. We confirmed that the synthesized composite films with Pt nanoparticles had an ordered pore structure with anatase phase TiO2 by both small-angle and wide-angle X-ray diffraction analyses. Although the porosity of the composite film decreased from 37.6 to 29.3% when Pt nanoparticles were included, the conductivity ratio (?/?) of the film increased greatly, up to approximately 1370 K V-2, due to the greater increase in electrical conductivity than thermal conductivity. Based on our results, we conclude that by incorporating Pt nanoparticles into ordered mesoporous TiO2 film, the thermoelectric properties of the mesoporous films can be improved.

Ha, Tae-Jung; Choi, Yong-June; Jung, Sin-Young; Seo, Won-Seon; Lim, Young Soo; Shin, Sangwoo; Cho, Hyung Hee; Park, Hyung-Ho

2011-07-01

196

Optimizing preparation of the TiO2 thin film reactor using the Taguchi method  

International Nuclear Information System (INIS)

In this study, titanium dioxide thin film was prepared using the modified chemical vapor deposition. The parameters employed to control the preparation of the catalyst include the temperature of water bath, the Ti(OC3H7)4/H2O ratio, the flow rate of carrier gas, the oxidation temperature, the oxidation time, the calcination temperature, the rotating speed of furnace, and the speed of geared motor. The orthogonal arrays in the design of experimental method proposed by Taguchi were adopted to conduct the multiple-factor experiment. The conversion rate of salicylic acid in the aqueous or heterogeneous phase photocatalysis experiment was employed to identify the optimal conditions for assembly. The results indicated that a higher conversion ratio of the organic substance could be achieved under catalytic oxidation temperature of 400 oC, calcination temperature of 550 oC, and spraying speed of 30 rpm and the optimal experimental conditions obtained in this study were irradiation with intensity of 2.9 mW cm-2 on salicylic acid at concentration of 250 mg L-1 by both agitation and aeration processes (dissolved oxygen level = 8.2 mg O2 L-1) at pH 5, which could achieve optimal hydroxyl radical yield of 5.1 x 10-17 M.

2010-04-01

197

The fabrication of visible light responsive Ag-SiO2 co-doped TiO2 thin films by the sol–gel method  

International Nuclear Information System (INIS)

In this study we have successfully deposited Ag-SiO2 co-doped TiO2 thin films on glass substrates by the sol–gel method. After being coated by a dip coating method, the film was transparent, smooth and had strong adhesion on the glass surface. The deposited film was characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–Vis), a scanning electron microscope (SEM) and atomic force microscope (AFM) to investigate its crystallization, transmittance and surface structure. The antifogging ability is explained by the contact angle of water on the surface of the glass substrates under visible-light. The obtained results show that Ag-SiO2 co-doped TiO2 film has potential applications for self cleaning and anti-bacterial ceramic tiles

2010-03-01

198

Optical and crystallisation behaviour of TiO2 and V/TiO2 thin films prepared by plasma and ion beam assisted methods  

International Nuclear Information System (INIS)

This paper reports the synthesis of TiO2 and V/TiO2 thin films, prepared by plasma enhanced and ion beam induced chemical vapour deposition procedures. Thin films with different contents of vanadium from a few to some tenth percents of this element have been prepared. Vanadium oxide thin films were also prepared for comparison. Morphological, structural and chemical characterisation of the samples was carried out by means of several techniques including scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Optical properties of these samples were studied by ellipsometry and ultraviolet-visible absorption spectroscopy. It has been shown that the absorption threshold of V/TiO2 thin films shifts continuously towards the visible by increasing the V content. On the basis of this behaviour it is proposed the use of these thin films as optical filters in the UV-vis region of the spectrum. In the 'as prepared' samples vanadium is homogeneously distributed within an amorphous Ti-O structure. After annealing in air at T>673 K, both segregation of vanadium as vanadium oxide and crystallisation of the TiO2 into the rutile structure take place. It is realised that infrared spectroscopy can be a complementary technique of XRD to determine the crystallisation behaviour of the samples. The observed structural modifications are accompanied by a change in the light absorption properties of the films that can now be interpreted as due to the superposition of the absorption spectra of TiO2 and vanadium oxide. In the ion beam assisted films, only slight changes in their refraction index (n) are found as a function of the vanadium content and/or the annealing treatments. The changes were greater for the less compact films obtained by plasma deposition, indicating that the main parameter controlling the value of n is the density of the films

2003-04-01

199

Effect of synthesis temperature on structure, optical and photovoltaic properties of TiO2 nanorod thin films  

International Nuclear Information System (INIS)

Highlights: ? Nanorods of TiO2 have been synthesized by a single step hydrothermal technique. ? The nanorods have tetragonal rutile structure. ? The Raman bands at 447.68 cm?1 and 613.98 cm?1 are Eg and A1g modes of rutile TiO2. ? Maximum light to electricity conversion efficiency for nanorod DSSC was 3.7%. ? The electron life time in the dye sensitized solar cell is as high as 0.19 s. - Abstract: We report a facile hydrothermal method for epitaxial growth of TiO2 nanorods directly on fluorine doped tin oxide substrates without any seed layer. The diameter, density, length and the phase of the nanorods depended on synthesis temperature. We observed a systematic increase in the width of the nanorod with increase in growth temperature. Single crystalline nanorods having tetragonal rutile structure were deposited at 150 °C whereas the nanorod film deposited at higher temperatures had polycrystalline nature. The absorption spectra of a typical nanorod film showed direct and indirect optical transitions at 3.28 eV and 2.66 eV, respectively. The Raman spectra contained two characteristic bands at 447.68 cm?1 and 613.98 cm?1 corresponding to rutile tetragonal TiO2. A light to electricity conversion efficiency of 3.7% could be achieved with a 2 ?m-thick TiO2 nanorod film photoanode dye sensitized solar cell. The electrochemical impedance spectroscopy result suggested that the internal resistances of the solar cells changed remarkably with variation in the growth temperatures of the photoanodes. The cell with minimum internal resistance and maximum carrier life time had maximum power conversion efficiency.

2012-03-30

200

Thin-film photo-catalytic TiO2 phase prepared by magnetron sputtering deposition, plasma ion implantation and metal vapor vacuum arc source  

International Nuclear Information System (INIS)

This study utilizes three methods, magnetron sputtering deposition (MSD), plasma ion implantation (PIII), and metal vapor vacuum arc (MeVVA), to prepare a thin-film TiO2. The formation of stoichiometrical TiO2-polymorphs as a layer is regularly relevant to the characteristic of the photo-catalytic effect. TiO2-polymorphs created at the outermost surface and initiated by efficient photons are still capable to produce superficial hydroxyl groups for subsequent photo-catalytic reactions. The MSD-treated surface with the majority of TiO2-anatase (101) surface is presently photo-catalytic. The PIII or MeVVA treatment results in an ion-implanted layer of different Ti / O ratios along with the detecting depths, whereas the Ti and O elements in TiO2 phase at the outermost surface of the layer can be distinguished. Although the PIII- or MeVVA-treated surface is relatively insignificant in photo-catalytic reactions assessed by water droplet contact angle, the consumption of methylene blue in water and antibacterial test, it is still potential to adjust their surface chemistry by improving the quality of the ion-implanted layer, roughening the contact surface area, and increasing the efficiency to regenerate the photo-catalytic reactions. In addition, the ion implantation methods do not alter the size and dimension of a substrate that is a great advantage to employ them for various advanced applications

2006-09-25

 
 
 
 
201

Hole-mediated Photodecomposition of Trimehtyl Acetate on a TiO2(001) Anatase Epitaxial Thin Film Surface  

Energy Technology Data Exchange (ETDEWEB)

Surfaces of titanium dioxide in both rutile and anatase polymorphs have attracted significant attention in catalysis and photochemistry. The (110) orientation of rutile, and to a lesser extent other rutile orientations, have been studied on an atomic scale, yielding information on surface structure and chemical reactivity. In contrast, the thermal and photochemistry of well-defined, single-crystal anatase surfaces had not been investigated, largely because of the metastable nature of anatase , as well as the lack of availability of high-quality surfaces. Here we describe a study of the adsorption and photoreactivity of an organic adlayer, trimethyl acetate (TMA), on structurally-excellent anatase (001) epitaxial thin films grown by oxygen plasma assisted molecular beam epitaxy (OPAMBE). High-resolution scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), and photodesorption spectrometry have been used to study the chemisorptions and ultraviolet (UV) light-induced photodecomposition of TMA in ultrahigh vacuum. UV light promotes hole-mediated photodecomposition of TMA, resulting in decarboxylation to yield tert-butyl radical and CO2. The photochemical rate constant is equal to that measured for OPAMBE grown rutile TiO2(110) surfaces.

Ohsawa, Takeo; Lyubinetsky, Igor; Henderson, Michael A.; Chambers, Scott A.

2008-12-18

202

Effect of deposition methods on the properties of photocatalytic TiO2 thin films prepared by spray pyrolysis and magnetron sputtering  

International Nuclear Information System (INIS)

Titanium dioxide thin films were deposited by DC reactive magnetron sputtering and spray pyrolysis methods onto glass and glass coated with fluorine doped tin oxide (FTO). The films were characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-visible spectroscopy. For films deposited by the sputtering technique we have studied the effect of the total pressure of an Ar-O2 mixture on the substrate properties, on the deposition rate, phase composition, crystallinity, surface morphology and on the photocatalytic properties. Also transparent TiO2 thin films have been prepared by spray pyrolysis using a low concentration of titanium precursor with different substrate temperatures. At higher substrate temperatures the films were polycrystalline in the anatase phase; at lower substrate temperatures the films presented an amorphous configuration. The photocatalytic properties of TiO2 thin films were tested with the degradation methylene blue under UV light irradiation. The higher degradation rates were reached for films prepared by spray pyrolysis with a substrate temperature close to 400 deg. C, and for a high total pressure (16 mTorr) for films deposited by DC magnetron sputtering

2004-06-09

203

Site-specific and patterned growth of TiO2 nanotube arrays from e-beam evaporated thin titanium film on Si wafer  

International Nuclear Information System (INIS)

Growth of TiO2 nanotubes on thin Ti film deposited on Si wafers with site-specific and patterned growth using a photolithography technique is demonstrated for the first time. Ti films were deposited via e-beam evaporation to a thickness of 350–1000 nm. The use of a fluorinated organic electrolyte at room temperature produced the growth of nanotubes with varying applied voltages of 10–60 V (DC) which remained stable after annealing at 500?°C. It was found that variation of the thickness of the deposited Ti film could be used to control the length of the nanotubes regardless of longer anodization time/voltage. Growth of the nanotubes on a SiO2 barrier layer over a Si wafer, along with site-specific and patterned growth, enables potential application of TiO2 nanotubes in NEMS/MEMS-type devices. (paper)

2012-09-28

204

Preparation of anatase TiO2 thin films for dye-sensitized solar cells by DC reactive magnetron sputtering technique  

International Nuclear Information System (INIS)

Anatase titanium dioxide (TiO2) thin films are prepared by DC reactive magnetron sputtering using Ti target as the source material. In this work argon and oxygen are used as sputtering and reactive gas respectively. DC power is used at 100 W per 1 h. The distance between the target and substrate is fixed at 4 cm. The glass substrate temperature value varies from room temperature to 400 oC. The crystalline structure of the films is determined by X-ray diffraction analysis. All the films deposited at temperatures lower than 300 oC were amorphous, whereas films obtained at higher temperature grew in crystalline anatase phase. Phase transition from amorphous to anatase is observed at 400 oC annealing temperature. Transmittances of the TiO2 thin films were measured using UV-visible NIR spectrophotometer. The direct and indirect optical band gap for room temperature and substrate temperature at 400 oC is found to be 3.50, 3.41 eV and 3.50, 3.54 eV respectively. The transmittance of TiO2 thin films is noted higher than 75%. A comparison among all the films obtained at room temperature showed a transmittance value higher for films obtained at substrate temperature of 400 oC. The morphology of the films and the identification of the surface chemical stoichiometry of the deposited film at 400 oC were studied respectively, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface roughness and the grain size are measured using AFM.

2010-11-30

205

Crystallization of BaTiO3 thin film at 140 .deg. C by metalorganic decomposition hydrothermal method using TiO2 precursor  

International Nuclear Information System (INIS)

BaTiO3 thin films with perovskite structure have been prepared on Pt/Ti/SiO2/Si substrate using a combined process of conventional MOD process and a hydrothermal treatment using TiO2 precursor. The BaTiO3 thin films were crystallized on silicon by hydrothermal treatment at temperature of 140 .deg. C. The structure development, stoichiometry, spectroscopic, and dielectric properties of BaTiO3 thin films have been systematically investigated. X-ray diffraction patterns show that well-developed crystallites with perovskite phase have been formed. BaTiO3 thin film obtained by the mono-treatment process shows (100) preferred orientation, but TiO2 peak still exists which indicated that the reaction is not completed. The stoichiometric BaTiO3 thin films with a (110) preferred orientation were obtained by the multi-treatment process. AFM observation shows that the roughness of surface is improved with the multi-treatment process. The electric properties of the sample prepared by the multi-treatment process is better than that prepared by the mono-treatment process

2003-04-01

206

Role of energy in low-temperature high-rate formation of hydrophilic TiO2 thin films using pulsed magnetron sputtering  

International Nuclear Information System (INIS)

The article reports on low-temperature high-rate deposition of hydrophilic TiO2 thin films using dc pulse dual magnetron (DM) sputtering in an Ar+O2 mixture on unheated glass substrates. DM is operated in a bipolar asymmetric mode and is equipped with Ti (99.5%) targets 50 mm in diameter. Main attention is concentrated on the investigation of the effect of an energy delivered to the TiO2-x film, growing on unheated and heated substrates, by the ion bombardment on its structure. The effect of the length and shape of the pulse on the structure and deposition rate aD of the film is investigated in detail. It is shown that (1) the shortening of the pulse length to about ?2 ?s strongly enhances the ion bombardment of electrically insulating film which makes it possible to form nanocrystalline strongly hydrophilic TiO2 films at low (?100 deg. C) values of the substrate temperature Ts and (2) the increase of a repetition frequency fr of pulses results in a strong increase of aD; aD increases almost two times when fr is increased from 100 to 300 kHz. It was found that (1) hydrophilic TiO2 films several hundred nanometers thick are crystalline and can be sputtered on unheated glass substrates with a high deposition rate aD=80 nm/min at substrate surface temperatures Tsurf?180 deg. C when fr=350 kHz is used and (2) hydrophilic TiO2-x films sputtered at low values of the substrate surface temperature Tsurf?100 deg. C exhibit nanocrystalline structure and can be formed if much lower deposition rates aD?5 nm/min are used. Correlations between the hydrophilicity of TiO2-x film, its structure, Tsurf, process parameters, and the film deposition rate aD are given. A summary of the present state of knowledge in this field is presented

2007-07-01

207

Preparation of platinum- and silver-incorporated TiO2 coatings in thin-film photoreactor for the photocatalytic decomposition of o-cresol.  

Science.gov (United States)

Platinum-incorporated TiO2 (Pt-TiO2) and silver-incorporated TiO2 (Ag-TiO2) coatings on sapphire tubes of a thin-film photoreactor were prepared using a photoreduction process. Results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) revealed that the Ag-TiO2 coatings consisted of a mixture of Ag2O, Ag and TiO2 particles, owing to the partial oxidization of silver particles on the TiO2 coatings, while the Pt-TiO2 coating contained a mixture of Pt and TiO2 particles. Diffuse reflectance UV-Vis spectra (DRS) showed that metal particles (Ag or Pt) incorporated into the TiO2 coatings promoted optical absorption in the visible region and made it possible for the coatings to be excited by visible light. Photoluminescence (PL) spectra showed that the PL intensity of the Pt-TiO2 coating was lower than that of the Ag-TiO2 and TiO2 coatings, indicating that the Pt-TiO2 coating had a higher efficiency of charge carrier trapping, immigration and transfer, which subsequently promoted the pseudo-first-order rate constants after the UV/TiO2 process. The Pt-TiO2 coatings for the photocatalytic decomposition of o-cresol under UV light irradiation corresponded to a higher pseudo-first-order rate constant (k) of 0.02 min(-1) when compared with the photocatalytic decomposition rates of pure TiO2 coatings (k = 0.0062 min(-1)) and Ag-TiO2 coatings (k = 0.01 min(-1)). The experimental results also indicated that the photodegradation rate of the Pt-TiO2 coating under visible light irradiation was significantly higher than the photodegradation rates of the Ag-TiO2 and pure TiO2 coatings. PMID:22439567

Kuo, Yu-Lin; Su, Te-Li; Chuang, Kai-Jen; Chen, Hua-Wei; Kung, Fu-Chen

2011-12-01

208

TiO2 and Al2O3 ultra thin nanolaminates growth by ALD; instrument automation and films characterization  

Directory of Open Access Journals (Sweden)

Full Text Available We report on the development of a fully operational atomic layer deposition (ALD system. This system is computer controlled and can deposit multilayered systems without user intervention. We describe the design of manifold, reaction chamber and exhaust. Additionally we give some features of the automatization software and electronics. To evaluate the ALD performance we used as precursor trymethyl aluminum (TMA and tetrakis (dimethylamino titanium (TDMAT to deposit Al2O3 and TiO2, respectively, in nanolaminated film structures. The thicknesses and composition of the films are precisely controlled, as determined by spectroscopic ellipsometry, and the nanolaminates have a sharp interface as indicated by Auger depth profile.

R. Machorro

2012-01-01

209

Understanding of gas phase deposition of reactive magnetron sputtered TiO2 thin films and its correlation with bactericidal efficiency  

International Nuclear Information System (INIS)

Highlights: ? Influence of O2 flow rates on the gas phase plasma during TiO2 film deposition was studied. ? The plasma parameters were determined and correlated with the film properties. ? O2 flow rate affects crystallinity, surface bonding, hydrophilicity, band gap and particle size of TiO2 films. ? These were found to be decisive factors for antibacterial property. ? These were found to be decisive factors for antibacterial property. - Abstract: Nanostructured TiO2 thin films were deposited using RF reactive magnetron sputtering at different O2 flow rates (20, 30, 50 and 60 sccm) and constant RF power of 200 W. In situ investigation of the nucleation and growth of the films was made by Optical Emission Spectroscopy (OES). The nano amorphous nature as revealed from X-ray diffraction (XRD) of the as deposited films and abundance of the Ti3+ surface oxidation states and surface hydroxyl group (OH?) in the films deposited at 50 sccm as determined from X-ray photo electron spectroscopy (XPS) was explained on the basis of emission spectra studies. The increase in band gap and decrease in particle size with O2 flow rate was observed from transmission spectra of UV–vis spectroscopy. Photoinduced hydrophilicity has been studied using Optical Contact Angle (OCA) measurement. The post irradiated films showed improved hydrophilicity. The bactericidal efficiency of these films was investigated taking Escherichia coli as model bacteria. The films deposited at 50 sccm shows better bactericidal activity as revealed from the optical density (OD) measurement. The qualitative analysis of the bactericidal efficiency was depicted from Scanning Electron Microscope images. A correlation between bactericidal efficiency and the deposited film has been established and explained on the basis of nucleation growth, band gap and hydrophilicity of the films.

2012-10-01

210

Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights  

International Nuclear Information System (INIS)

Sn-doped and undoped nano-TiO2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO2 thin film

2007-02-09

211

On the optical, structural, and morphological properties of ZrO2 and TiO2 dip-coated thin films supported on glass substrates  

International Nuclear Information System (INIS)

This article reports the optical and morphological properties of dip-coated TiO2 and ZrO2 thin films on soda-lime glass substrates by metal-organic decomposition (MOD) of titaniumIV and zirconiumIV acetylacetonates respectively. Thermogravimetric and differential thermal analysis (DTA-TG) were performed on the precursor powders, indicating pure TiO2 anatase and tetragonal ZrO2 phase formation. Phase crystallization processes took place in the range of 300-500 deg. C for anatase and of 410-500 deg. C for ZrO2. Fourier Transform Infrared Spectroscopy (FT-IR) was used to confirm precursor bidentate ligand formation with keno-enolic equilibrium character. Deposited films were heated at different temperatures, and their structural, optical and morphological properties were studied by grazing-incidence X-ray Diffraction (GIXRD) and X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet Visible Spectroscopy (UV-Vis), and Atomic Force Microscopy (AFM) respectively. Film thinning and crystalline phase formation were enhanced with increasing temperature upon chelate decomposition. The optimum annealing temperature for both pure anatase TiO2 and tetragonal ZrO2 thin films was found to be 500 deg. C since solid volume fraction increased with temperature and film refractive index values approached those of pure anatase and tetragonal zirconia. Conditions for clean stoichiometric film formation with an average roughness value of 2 nm are discussed in terms of material binding energies indicated by XPS analyses, refractive index and solid volume fraction obtained indirectly by UV-Vis spectra, and crystalline peak identification provided by GIXRD

2005-11-01

212

Atomic Layer Deposition, Characterization, and Growth Mechanistic Studies of TiO2 Thin Films.  

Science.gov (United States)

Two heteroleptic titanium precursors were investigated for the atomic layer deposition (ALD) of titanium dioxide using ozone as the oxygen source. The precursors, titanium (N,N'-diisopropylacetamidinate)tris(isopropoxide) (Ti(O(i)Pr)3(N(i)Pr-Me-amd)) and titanium bis(dimethylamide)bis(isopropoxide) (Ti(NMe2)2(O(i)Pr)2), exhibit self-limiting growth behavior up to a maximum temperature of 325 °C. Ti(NMe2)2(O(i)Pr)2 displays an excellent growth rate of 0.9 Å/cycle at 325 °C while the growth rate of Ti(O(i)Pr)3(N(i)Pr-Me-amd) is 0.3 Å/cycle at the same temperature. In the temperature range of 275-325 °C, both precursors deposit titanium dioxide in the anatase phase. In the case of Ti(NMe2)2(O(i)Pr)2, high-temperature X-ray diffraction (HTXRD) studies reveal a thickness-dependent phase change from anatase to rutile at 875-975 °C. X-ray photoelectron spectroscopy (XPS) indicates that the films have high purity and are close to the stoichiometric composition. Reaction mechanisms taking place during the ALD process were studied in situ with quadrupole mass spectrometry (QMS) and quartz crystal microbalance (QCM). PMID:24896967

Kaipio, Mikko; Blanquart, Timothee; Tomczak, Yoann; Niinistö, Jaakko; Gavagnin, Marco; Longo, Valentino; Wanzenböck, Heinz D; Pallem, Venkateswara R; Dussarrat, Christian; Puukilainen, Esa; Ritala, Mikko; Leskelä, Markku

2014-07-01

213

Photocatalytic performance of Sn-doped TiO2 nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights  

International Nuclear Information System (INIS)

Sn-doped and undoped nano-TiO2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO2 based thin films, contain at different solid ratio of TiO2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

2008-01-08

214

Schottky junction/ohmic contact behavior of a nanoporous TiO2 thin film photoanode in contact with redox electrolyte solutions  

Directory of Open Access Journals (Sweden)

Full Text Available The nature and photoelectrochemical reactivity of nanoporous semiconductor electrodes have attracted a great deal of attention. Nanostructured materials have promising capabilities applicable for the construction of various photonic and electronic devices. In this paper, a mesoporous TiO2 thin film photoanode was soaked in an aqueous methanol solution using an O2-reducing Pt-based cathode in contact with atmospheric air on the back side. It was shown from distinct photocurrents in the cyclic voltammogram (CV that the nanosurface of the mesoporous n-TiO2 film forms a Schottky junction with water containing a strong electron donor such as methanol. Formation of a Schottky junction (liquid junction was also proved by Mott–Schottky plots at the mesoporous TiO2 thin film photoanode, and the thickness of the space charge layer was estimated to be very thin, i.e., only 3.1 nm at ?0.1 V vs Ag/AgCl. On the other hand, the presence of [Fe(CN6]4? and the absence of methanol brought about ohmic contact behavior on the TiO2 film and exhibited reversible redox waves in the dark due to the [Fe(CN6]4?/3? couple. Further studies showed that multiple Schottky junctions/ohmic contact behavior inducing simultaneously both photocurrent and overlapped reversible redox waves was found in the CV of a nanoporous TiO2 photoanode soaked in an aqueous redox electrolyte solution containing methanol and [Fe(CN6]4?. That is, the TiO2 nanosurface responds to [Fe(CN6]4? to give ohmic redox waves overlapped simultaneously with photocurrents due to the Schottky junction. Additionally, a second step photocurrent generation was observed in the presence of both MeOH and [Fe(CN6]4? around the redox potential of the iron complex. It was suggested that the iron complex forms a second Schottky junction for which the flat band potential (Efb lies near the redox potential of the iron complex.

Masao Kaneko

2011-02-01

215

Facile solution-controlled growth of CuInS2 thin films on FTO and TiO2/FTO glass substrates for photovoltaic application  

International Nuclear Information System (INIS)

This paper reports on the preparation of two thin films (CuInS2/FTO and CuInS2/TiO2/FTO) by a facile solvothermal method and their photovoltaic properties. Instrumental measurements including X-ray diffraction (XRD), inductively coupled plasma emission spectroscopy (ICP), scanning electron microscopy (SEM), and UV-vis spectra have been used to characterize the obtained CuInS2 thin films. The results show that the CuInS2 films deposited on fluorine-doped tin oxide-coated (FTO) conductive glass substrates are composed of nanoplates and microspheres. The thickness of the CuInS2/FTO films can be adjusted from 1 ?m to 8 ?m by controlling the solution concentration of the reactants. While, the prepared 10 ?m-thick CuInS2 film on the TiO2 film substrate consists of nanoplates. The UV-vis absorption spectra reveal that the CuInS2 thin films have a strong absorption around 400-850 nm and the band-gap energy is tunable in the range of 1.45-1.61 eV with the variation of Cu/In ratio from 1.20 to 0.90. Furthermore, two types of thin film solar cells, which have an effective area of 0.25 cm2 and possess separately the top-down composition of Ag/CdS/CuInS2/FTO and FTO/TiO2/CuInS2/Au, were fabricated after heat-treatment to evaluate their photovoltaic properties and the corresponding conversion efficiency is 0.33% and 0.29% under AM 1.5 irradiation (100 mW cm-2), respectively.

2009-07-29

216

Surface characterization of poly(methylmethacrylate) based nanocomposite thin films containing Al2O3 and TiO2 nanoparticles  

International Nuclear Information System (INIS)

Poly(methylmethacrylate) (PMMA) based nanocomposite electron beam resists have been demonstrated by spin coating techniques. When TiO2 and Al2O3 nanoparticles were directly dispersed into the PMMA polymer matrix, the resulting nanocomposites produced poor quality films with surface roughnesses of 322 and 402 nm respectively. To improve the surface of the resists, the oxide nanoparticles were encapsulated in toluene and methanol. Using the zeta potential parameter, it was found that the stabilities of the toluene/oxide nanoparticle suspensions were 7.7 mV and 19.4 mV respectively, meaning that the suspension was not stable. However, when the TiO2 and Al2O3 nanoparticles were encapsulated in methanol the zeta potential parameter was 31.9 mV and 39.2 mV respectively. Therefore, the nanoparticle suspension was stable. This method improved the surface roughness of PMMA based nanocomposite thin films by a factor of 6.6 and 6.4, when TiO2 and Al2O3 were suspended in methanol before being dispersed into the PMMA polymer.

2010-03-01

217

Al2O3/TiO2 Nanolaminate Thin Film Encapsulation for Organic Thin Film Transistors via Plasma-Enhanced Atomic Layer Deposition.  

Science.gov (United States)

Organic electronic devices require a passivation layer that protects the active layers from moisture and oxygen because most organic materials are very sensitive to such gases. Passivation films for the encapsulation of organic electronic devices need excellent stability and mechanical properties. Although Al2O3 films obtained with plasma enhanced atomic layer deposition (PEALD) have been tested as passivation layers because of their excellent gas barrier properties, amorphous Al2O3 films are significantly corroded by water. In this study, we examined the deformation of PEALD Al2O3 films when immersed in water and attempted to fabricate a corrosion-resistant passivation film by using a PEALD-based Al2O3/TiO2 nanolamination (NL) technique. Our Al2O3/TiO2 NL films were found to exhibit excellent water anticorrosion and low gas permeation and require only low-temperature processing (relative humidity of 90% and a temperature of 38 °C)) were fabricated. PMID:24712401

Kim, Lae Ho; Kim, Kyunghun; Park, Seonuk; Jeong, Yong Jin; Kim, Haekyoung; Chung, Dae Sung; Kim, Se Hyun; Park, Chan Eon

2014-05-14

218

Low-temperature atomic layer deposition of TiO2, Al2O3, and ZnO thin films  

International Nuclear Information System (INIS)

We studied low-temperature atomic layer deposition (LT-ALD) of TiO2, Al2O3, and ZnO thin films at temperatures down to room temperature, mainly focusing on the growth characteristics and the film's properties. Here, two kinds of ALD deposition systems were introduced. Initially, for the thermal ALD (T-ALD) process using a commercial ALD system, a very long purging time of up to ?300 s was required to entirely evacuate the remaining H2O vapors at room temperature due to the large volume and the complicated inner structure of the commercial ALD chamber. For the realization of LT-ALD with a short process time, a plasma-enhanced ALD (PE-ALD) process using O2 plasma was employed, which enabled us to effectively remove the residual reactants at temperatures down to room temperature. As another method, we specifically designed a homemade ALD system with a small volume and a simple inner structure, thereby being able to use T-ALD to synthesize TiO2, Al2O3, and ZnO thin films by using H2O with very short H2O purging times even at room temperature, which reveals that the chamber size and design are the critical factors enabling LT-ALD with a short process time. The LT-ALD processes produced highly-pure Al2O3, TiO2, and ZnO films without any C and N impurities by complete elimination of ligands and exhibited excellent conformality in 3-dimensional nanoscale via holes.

2011-08-01

219

Preparation and characterization of increased-efficiency photocatalytic TiO2-2xNx thin films  

International Nuclear Information System (INIS)

We report here on the characteristics of RF-sputtered 300 nm thick films of TiO2-2xNx prepared on glass substrates at 350 deg. C, by adjusting the N2:Ar partial pressure ratio in the deposition chamber between 0.00 and 0.33. XRD, XPS, AFM and contact angle data were used to derive film structure, elemental composition and oxidation state of Ti, surface morphology and hydrophilicity, respectively. The band gap was derived from spectral data in the 350-450 nm range. Film structure and composition were changed by adjusting the partial pressure of the reactive gases during sputtering and by post-deposition annealing at 400 deg. C in air, for 90 min. The values of the contact angle of films' surface with de-ionized water and of surface free energy per unit area show that films are super-hydrophilic for high-nitrogen content. Correlations are made between film structure, elemental composition, electronic and wettability properties

2007-10-15

220

Real-time identification of the evolution of conducting nano-filaments in TiO2 thin film ReRAM.  

Science.gov (United States)

Unipolar resistance switching (RS) in TiO2 thin films originates from the repeated formation and rupture of the Magnéli phase conducting filaments through repeated nano-scale phase transitions. By applying the Johnson-Mehl-Avrami (JMA) type kinetic model to the careful analysis on the evolution of transient current in a pulse-switching, it was possible to elucidate the material specific evolution of the Magnéli phase filament. This methodology was applied to the two types of TiO2 films grown by plasma-enhanced atomic layer deposition (PEALD) and sputtering. These two samples have structurally and electrically distinctive properties: PEALD film exhibited high variability in switching parameters and required an electroforming while sputtered film showed higher uniformity without distinct electroforming process. The JMA-type kinetic analysis of the RS behaviors revealed that the rejuvenation of the filament is accomplished by repeated one-dimensional nucleation followed by a two-dimensional growth in PEALD samples, whereas one-dimensional nucleation-free mechanism dominates in sputtered films. PMID:24309421

Song, Seul Ji; Seok, Jun Yeong; Yoon, Jung Ho; Kim, Kyung Min; Kim, Gun Hwan; Lee, Min Hwan; Hwang, Cheol Seong

2013-01-01

 
 
 
 
221

Preparation and characterization of hydrophobic organic-inorganic composite thin films of PMMA/SiO2/TiO2 with low friction coefficient  

International Nuclear Information System (INIS)

Organic-inorganic polymethacrylate (PMMA)/SiO2/TiO2 composite thin films with controlled thickness and hydrophobicity have been synthesized. The precursor solution of hybrid systems based on 3-trimethoxysilyl propyl methacrylate (TMSM), tetramethylorthosilicate (TMOS), methyl methacrylate (MMA), and tetrabutyl titanate (TBT) were prepared by sol-gel processes. The in situ derivatization of the precursor solution by perfluoroalkylsulfonyl alkyl triakoxy silane C8F17SO2NHC3H6Si(OCH3)3 (trade name: FC-922) effectively increases the hydrophobicity of the film with a contact angle for water of more than 100 deg. . The structure and properties of the hybrid composite thin film were investigated using TG/DTA, FT-IR, XRD, XPS, and AFM. The thickness of the thin film was less than 120 nm which was measured by cross-sectional scanning electron microscopy. The tribological behavior of the thin film was examined. The friction coefficient of the film prepared is very low (0.09-0.11), and the anti-wear behavior is good, with a lack of failure even after 8000 sliding passes. These films are meeting practical lubricant and protection process requirements, including low processing temperature, high thermal stability, and reliable mechanical properties

2004-01-15

222

Effect of Diethanolamine on Property of Thin Film TiO2 in Treating Hexavalent Chromium from Aqueous Solution  

International Nuclear Information System (INIS)

In this research titanium dioxide thin film was synthesized from hydrolysis and condensation process by sol-gel method. Titanium alkoxide was used as initial substrate. The solvent was ethanal and the additive substance was diethanolamine. All substances are mixed altogether in different ratios. To study the effect of diethanolamine on properties of titanium dioxide thin film, various film analysis were performed which included mass weighing, adhesive test, corrosion test using acid and alkali, surface morphology analysis with scanning electron microscope (SEM), thin film structure analysis using X-ray diffraction (XRD), and photo activity by chromium removal test. It was found that diethanolmine enhanced the film strength and improved the adhesive property. The smooth surface was obtained. This thin film showed the effectiveness in chromium removal with high photo activity. Even tough the developed thin film can remove chromium (VI) efficiently, the reaction rate constant (k) was slightly reduced from that using the normal thin film titanium dioxide (without adding diethanolamine). In addition, the reaction time is required little longer to accomplish the chromium (VI) removal with the same performance

2006-04-01

223

Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights  

International Nuclear Information System (INIS)

Nanostructure Sn4+-doped TiO2 based mono and double layer thin films, contain 50% solid ratio of TiO2 in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn4+-doped nano-TiO2 particle a doping ratio of about 5[Sn4+/Ti(OBu n)4; mol/mol%] has been synthesized by hydrotermal process at 225 deg. C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

2007-06-01

224

Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights.  

Science.gov (United States)

Nanostructure Sn(4+)-doped TiO(2) based mono and double layer thin films, contain 50% solid ratio of TiO(2) in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn(4+)-doped nano-TiO(2) particle a doping ratio of about 5[Sn(4+)/Ti(OBu(n))(4); mol/mol%] has been synthesized by hydrotermal process at 225 degrees C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO(2) particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property. PMID:17118537

Sayilkan, F; Asiltürk, M; Tatar, P; Kiraz, N; Arpaç, E; Sayilkan, H

2007-06-01

225

Derivation and Optical Properties of Co, Mn, Nd Doped SiOand SiO2-TiO2 Thin Films  

International Nuclear Information System (INIS)

In this research, SiO2-TiO2 and Co, Mn, Nd doped SiO2 thin films were prepared by the sol-gel-dip coating method on glass substrates using Si(OC2H5)4 (TEOS, tetraethylorthosilicate) and Ti(OBu)4 (tetrabutylorthotitanate) as starting materials. Precursor solutions were prepared by dissolving Si(OC2H5)4 and Ti(OBu)4 in ethanol. Various layers of coatings were obtained at room temperature by sol-gel dip-coating process at a withdrawal speed of 10 mm/sec. The coated substrates were exposed to heat treatment at 650 degree. The effect of chemistry of the precursor solution on the microstructure and optical properties of the films were examined by UV-VIS, AFM (Atomic Force Microscopy) and SE (Spectroscopic Ellypsometry). Band gaps of the films were determined by using absoption spectrum

2008-08-25

226

Research on TiO2-Based Photocatalyst Thin Film and Its Application in a Pilot-Scale Supply Water Treatment System  

Directory of Open Access Journals (Sweden)

Full Text Available In order to utilize the abundant natural sunlight in Hochiminh City for energy-saving purpose, the application of TiO2-based photocatalyst thin film coated on ceramic beads in a pilot-scale supply water treatment system of 2 m3/day was studied in this present work. The photocatalyst thin film was prepared by sol-gel and spray coating methods. The derived photocatalyst thin film presented high BET specific surface area of more than 160 m2/g while it also maintained good crystallinity. These superior physicochemical properties of the photocatalyst were well consistent with its strong photoactivity in the pilot-scale supply water treatment system. Groundwater after passed through ferric removal and sandfilter systems was treated in the pilot-scale supply water treatment system using the photocatalyst thin film. The COD, TOC and coliform removal efficiencies were measured at 63%, 51% and 100%, respectively by using the above system under natural sunlight in Hochiminh City.

The-Vinh Nguyen

2009-01-01

227

TiO2 thin layers with controlled morphology for ETA (extremely thin absorber) solar cells  

International Nuclear Information System (INIS)

The paper presents the synthesis process of dense and nanoporous TiO2 anatase films obtained via Spray Pyrolysis Deposition (SPD). The deposition of dense and nanostructured TiO2 films uses ethanol solutions of titaniumtetraisopropoxid and acetilacetonate. The influence of the precursor's concentration and deposition parameters (temperature, pressure of the carrier gas and distance of spraying) in tailoring the TiO2 morphology is presented. The films are tested via X-ray Diffraction and Scanning Electron Microscopy. The photoelectrical properties are tested by current-voltage (I-V) experiments in dark, at room temperature. According to the results, SPD proves to be a reliable technique in obtaining thin layers of TiO2 with controlled morphology

2006-07-26

228

DIRECT PHOTODEPOSITION OF NANOSTRUCTURED TIO2 THIN FILMS FROM B-DIKETONATE COMPLEXES, AND THEIR PHOTOCATALYTIC BEHAVIOUR  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Amorphous Titania thin films have been photochemically obtained by direct UV irradiation (254 nm) of an amorphous TiO(C6H5COCHCOCH3) 2 film spin-coated on Si(100) and borosilicate glass. These materials were characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD) an [...] d Auger electron spectroscopy (AES). SEM analysis showed a porous film with irregular morphology (diameter

M, TEJOS; G.E., BUONO-CUORE; F.R., DÍAZ; M.A., DEL VALLE; J, PALOMARES.

229

Thin films of a self-assembling peptide on TiO2 and Au studied by NEXAFS, XPS and IR spectroscopies  

International Nuclear Information System (INIS)

EAK16 is a 16 amino acid peptide consisting of an alternation of polar and non-polar pending groups and of positively and negatively charged residues, that makes this material capable of self-assembling, producing an extended ordered structure. Thin films of EAK16 were prepared on TiO2 and Au surfaces and investigated by surface-sensitive techniques such as XPS (X-ray photoelectron spectroscopy), NEXAFS (near edge X-ray absorption fine structure) and IR spectroscopies. XPS analysis allowed to check the chemical structure of the samples and to determine the film thickness. IR experiments yielded evidence of the ?-sheet conformation of the peptide backbone. Polarization dependent NEXAFS measurements allowed estimating the angle between the axis of the peptide backbone and the sample surface

2006-07-01

230

Novel Method of Preparation of Gold-Nanoparticle-Doped TiO2 and SiO2 Plasmonic Thin Films: Optical Characterization and Comparison with Maxwell-Garnett Modeling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

SiO2 and TiO2 thin films with gold nanoparticles (NPs) are of particular interest as photovoltaic materials. A novel method for the preparation of spin-coated SiO2-Au and TiO2-Au nanocomposites is presented. This fast and inexpensive method, which includes three separate stages, is based on the in situ synthesis of both the metal-oxide matrix and the Au NPs during a baking process at relatively low temperature. It allows the formation of nanocomposite thin films with a higher concentration of...

2011-01-01

231

Optical and structural properties of nanocrystalline anatase (TiO2) thin films prepared by non-aqueous sol-gel dip-coating  

International Nuclear Information System (INIS)

Anatase (TiO2) thin films were grown by non-aqueous sol-gel dip-coating using titanium (IV) n-butoxide as precursor and 1-butanol as solvent. High withdrawal speed of 4.7 mm/s in dip-coating resulted in defect free films of 100 nm average film thickness after subsequent heat treatments. According to scanning electron microscope and X-ray diffraction measurements, the films consisted of nanocrystalline anatase with 30 nm mean crystallite size. Refractive index n(?) and extinction coefficient k(?) were determined over the wavelength range from 200 to 1650 nm. The optical band gap of the film material was approximately 3.2 eV. The results showed very similar optical characteristics to those that are accomplished with chemically more reactive aqueous sol-gel processes. Furthermore, it was found that in addition to porosity, coordination number of Ti atoms to nearest oxygen neighbors is likely to have a significant role in explaining differences of optical properties between bulk anatase and thin film materials of the present work.

2011-07-01

232

Raman scattering and x-ray diffractometry studies of epitaxial TiO2 and VO2 thin films and multilayers on ?-Al2O3(11 bar 20)  

International Nuclear Information System (INIS)

Epitaxial thin films of TiO2 and VO2 single layers and TiO2/VO2 multilayers were grown on (11 bar 20) sapphire (?-Al2O3) substrates using the metalorganic chemical vapor deposition technique and were characterized using Raman scattering and four x-ray diffractometry. X-ray diffraction results indicate that the films are high quality single crystal material with well defined growth plane and small in-plane and out-of-plane mosaic. Single-layer films are shown to obey the Raman selection rules of TiO2 and VO2 single crystals. The close adherence to the Raman selection rules indicates the high degree of orientation of the films, both parallel and perpendicular to the growth plane. Selection rule spectra of two and three layer TiO2/VO2 multilayers are dominated by the VO2 layers with only minimal signature of the TiO2 layers. Due to the low band gap of semiconducting vanadium dioxide, we attribute the strong signature of the VO2 layers to resonant enhancement of the VO2 Raman component accompanied with absorption of the both the incident and scattered laser light from the TiO2 layers

1993-03-15

233

TiO2/CdS nanocomposite films: fabrication, characterization, electronic and optical properties  

International Nuclear Information System (INIS)

In this work, TiO2 nanocrystalline thin films were obtained through evaporating Ti films by electron beam deposition (EBD) followed by thermal treatment. The results show that after annealing at 300, 400 and 450?°C for 8?h, the obtained TiO2 thin films have nanoparticle and nanorod structures of 15–30?nm diameter and 100–300?nm length. At 750?°C for 8?h, the rutile phase was formed. The incorporation of cadmium sulfide (CdS) into TiO2 nanoparticle thin films was investigated. A CdS thin film was vacuum deposited onto the pre-deposited TiO2 film by a thermal evaporation technique. The obtained TiO2 and TiO2/CdS nanocomposite films were characterized by x-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The TiO2/CdS composite film was used in a photo-electrochemical (PEC) cell as a working electrode and in a platinum electrode as a counter electrode. The electrolyte solution contains 1?M KCl and 0.1?M Na2S. The results show that the cell with the TiO2/CdS composite film electrode has significantly improved photoelectric capability in comparison with that of pure TiO2 thin films, and the best thickness of the CdS thin film deposited on the ITO/TiO2 substrates is 70–140?nm

2010-03-01

234

Impact of water quality on removal of carbamazepine in natural waters by N-doped TiO2 photo-catalytic thin film surfaces  

International Nuclear Information System (INIS)

Highlights: ? N-doped TiO2 thin films have been deposited by sol–gel dip-coating. ? CBZ removal improved with increasing medium pH in the range of 5–9. ? DOC at a concentration of 5 mg/L resulted in an ?20% reduction in CBZ removal. ? Alkalinity values of 100 mg/L as CaCO3 resulted in a 40% decrease in CBZ removal. ? Complete suppression of the photocatalytic process in wastewater effluent. -- Abstract: Photocatalytic experiments on the pharmaceutical pollutant carbamazepine (CBZ) were conducted using sol–gel nitrogen-doped TiO2-coated glass slides under a solar simulator. CBZ was stable to photodegradation under direct solar irradiation. No CBZ sorption to the catalyst surface was observed, as further confirmed by surface characterization using X-ray photoelectron spectroscopic analysis of N-doped TiO2 surfaces. When exposing the catalyst surface to natural organic matter (NOM), an excess amount of carbon was detected relative to controls, which is consistent with NOM remaining on the catalyst surface. The catalyst surface charge was negative at pH values from 4 to 10 and decreased with increasing pH, correlated with enhanced CBZ removal with increasing medium pH in the range of 5–9. A dissolved organic carbon concentration of 5 mg/L resulted in ?20% reduction in CBZ removal, probably due to competitive inhibition of the photocatalytic degradation of CBZ. At alkalinity values corresponding to CaCO3 addition at 100 mg/L, an over 40% decrease in CBZ removal was observed. A 35% reduction in CBZ occurred in the presence of surface water compared to complete suppression of the photocatalytic process in wastewater effluent

2013-01-15

235

Characterization of thin TiO2 films prepared by plasma enhanced chemical vapour deposition for optical and photocatalytic applications  

International Nuclear Information System (INIS)

Thin titanium oxide films were deposited using a radio frequency (RF) plasma enhanced chemical vapour deposition method. Their optical properties and thickness were determined by means of ultraviolet-visible absorption spectrophotometry. Films of the optical parameters very close to those of titanium dioxide have been obtained at the high RF power input. Their optical quality is high enough to allow for their use in a construction of stack interference optical filters. At the same time, these materials exhibit strong photocatalytic effects. The results of structural analysis, carried out by Raman Shift Spectroscopy, show that the coatings posses amorphous structure. However, Raman spectra of the same films subjected to thermal annealing at 450 oC disclose an appearance of a crystalline form, namely that of anatase. Surface morphology of the films has also been characterized by Atomic Force Microscopy revealing granular, broccoli-like topography of the films.

2009-07-31

236

Clustering of impurity atoms in Co-doped anatase TiO2 thin films probed with soft x-ray fluorescence  

International Nuclear Information System (INIS)

The electronic structure of Co-doped anatase TiO2 epitaxial thin films grown at different partial oxygen pressures is investigated using soft x-ray emission spectroscopy. The resonantly excited Co L2,3 x-ray emission spectra of ferromagnetic Ti0.96Co0.04O2 samples for the oxygen-deficient regime show that the ratio of integral intensities for Co L2 and L3 emission lines significantly decreases with respect to nonmagnetic samples in the oxygen-rich regime. This is due to L2L3M4,5 Coster-Kronig transitions and suggests that ferromagnetic Ti0.96Co0.04O2 samples have n-type charge carriers and Co-Co bonds between substitutional and interstitial Co atoms are present while Co-O bonds are dominant in nonmagnetic Ti0.96Co0.04O2 samples in the oxygen-rich regime. Electronic structure calculations show that the presence of free charge carriers and Co segregation play a crucial role in strong ferromagnetism at room temperature in Co-doped TiO2

2006-05-03

237

Nanostructured columnar heterostructures of TiO2 and Cu2O enabled by a thin-film self-assembly approach: Potential for photovoltaics  

Energy Technology Data Exchange (ETDEWEB)

Significant efforts are being devoted to the development of semiconductor thin film and nanostructured material architectures as components of solar energy harvesting and conversion devices. In particular, nanostructured assemblies with well-defined geometrical shapes have emerged as possible highly efficient and economically viable alternatives to planar junction thin film architectures , , , . However, fabrication of inorganic nanostructures generally requires complicated and multiple step processing techniques, making them less suitable for large-scale manufacturing. Hence, innovative cell architectures and materials processing schemes are essential to large-scale integration and practical viability in photovoltaic devices. Here we present here a new approach towards nanostructured thin film solar cells, by exploiting phase-separated self-assembly , . Through a single-step deposition by rf magnetron sputtering, we demonstrate growth of an epitaxial, composite film matrix formed as self-assembled, well ordered, phase segregated, and oriented p-n type interfacial nanopillars of Cu2O and TiO2. The composite films were structurally characterized to atomic resolution by a variety of analytical tools, and evaluated for preliminary optical properties using absorption measurements. We find nearly atomically distinct Cu2O-TiO2 interfaces (i.e. a p-n junction), and an absorption profile that captures a wide range of the solar spectrum extending from ultraviolet to visible wavelengths. This work opens a novel avenue for development of simple and cost-effective optically active thin film architectures, and offers promise for significantly increased photovoltaic device efficiencies using nanostructured cells that can be optimized for both incident light absorption and carrier collection.

Polat, Ozgur [ORNL; Aytug, Tolga [ORNL; Lupini, Andrew R [ORNL; Paranthaman, Mariappan Parans [ORNL; Ertugrul, Memhet [Ataturk University; Bogorin, Daniela Florentina [ORNL; Meyer III, Harry M [ORNL; Wang, Wei [ORNL; Pennycook, Stephen J [ORNL; Christen, David K [ORNL

2013-01-01

238

Effect of Sn ratio on the photocatalytic degradation of methylene blue and soot of ink by TiO2-SnO2 nanostructured thin films  

International Nuclear Information System (INIS)

The photocatalytic performance of rutile-, anatase- and mixed-phases of nanocomposite TiO2-SnO2 thin films, with different Sn ratios was tested. The absorption spectra of the prepared films show enhancement of high absorbance in the visible region for samples with Ti to Sn ratios of 3:1. Degradation of both methylene blue (MB) and soot of ink (SI) was examined by transmittance change under UV-vis irradiation. Sn doping improved the photocatalytic activity of the films. The results reveal that the smoother the sample surface and smaller the particle size; the highest the photocatalytic activity. Moreover, thin films doped with Ti to Sn ratios of 50:1 and 3:1 photocatalyst could more readily photodegrade MB and SI under visible-light irradiation. The high visible-light catalytic activity of the prepared photocatalyst resulted from the high absorbance in the visible-light range and also the reduced electron-hole recombination rate.

2010-05-15

239

Enhancement of NMP Degradation Under UV Light by Nitrogen-Doped TiO2 Thin Films Using a Design of Experiment  

Directory of Open Access Journals (Sweden)

Full Text Available Doping nitrogen within TiO2 is an effective way to enhance visible light photocatalysis due to a direct electron excitation from the N2p states within the band gap. However, nitrogen doping is not always efficient for UV photocatalytic activity. Here, different structures of N-doped TiO2 (TiOxNy have been prepared by reactive RF (13.56 MHz magnetron sputtering. The morphological, optical, structural, and photocatalytic properties of the films have been studied in order to investigate the competitive effect of the morphology and the chemical composition on the efficiency of the photocatalytic activity. The variation of surface wettability of the film over time in the dark and under visible and UV irradiation was also studied. The reduction in wettability by dark storage can be explained by the adsorption of hydrocarbon contamination on the thin film’s surface. Additionally, from water contact angle experiments, it was found that these films developed hydrophilic properties upon UV and visible illumination. The photoinduced change in the contact angle of water was due to the removal of hydrocarbon contamination on the surface and also the photo-oxidation of the water droplet. Samples prepared at high pressure gave the best photocatalytic activity, even though the deposition rate was lower at higher pressures (lower film thicknesses, due to the high specific surface area and the optimal presence of TiOxNy crystals in the lattice. However, at low pressure, the TiN crystals became more predominant, and acted as recombination centers for the photo-generated charge carriers. A design of experiments was used in order to optimize the deposition parameters to have the best photocatalytic activity. The high photocatalytic activity under UV light was found to be due to the introduction of discrete energy levels within the band gap, the increased sample wettability, and the higher specific surface area. However, the post annealing process did not effect the activity under UV irradiation. Using the response surface methodology, RSM, based on a design of experiment, DOE, we are able to achieve a good understanding of the complex processes involved in the deposition of the thin films and their effect on the photocatalytic activity.

F. Arefi-Khonsari

2011-01-01

240

Structural and electrochromic properties of TiO2 thin films prepared by metallorganic chemical vapor deposition  

International Nuclear Information System (INIS)

Titanium dioxide thin films were deposited by Metallorganic Chemical Vapor Deposition at substrate temperatures ranging from 250 oC to 450 oC over soda lime glass and indium tin oxide coated glass substrates. X-ray diffraction studies show that films have a crystalline anatase structure at all the deposition temperatures. Particle size decreases and texture changes with the increase in substrate temperature. X-ray photoelectron spectroscopy confirms the appearance of a new well resolved state in the core level of Ti 2p spectrum shifted by 1.16 eV to lower binding energy due to the reduction of Ti+4 to Ti+3 upon litheation. Chronoamperometery, cyclic voltammetery and in situ UV-Vis spectrophotometeric studies were carried out on the prepared samples. Particle size and crystallinity control the electrochromic performance. The 350 oC film shows the highest ion storage capacity and the highest optical modulation along with an appreciable band gap broadening.

2010-07-30

 
 
 
 
241

Methylene blue photoelectrodegradation under UV irradiation on Au/Pd-modified TiO2 films  

International Nuclear Information System (INIS)

In this work TiO2 thin films were modified with gold/palladium (Au/Pd) bimetallic paticles by sputtering method. TiO2 films were deposited on ITO (SnO2:In) by Doctor Blade method and post-anneling. The properties of the films were studied through measurements of XRD (X-ray diffraction) and AFM (atomic force microscopy). The degradation of methylene blue was studied by UV-irradiated pure TiO2 and Au/Pd-modified TiO2 in aqueous solution. Langmuir-Hinshelwood model was used to obtain kinetic information. Photocatalytic study indicated that Au/Pd-modified TiO2 photocatalytic activity was better than TiO2 pure; the best half-life time for Au/Pd-modified TiO2 in photodegradation was 2.8 times smaller than TiO2 pure; finally the efficiency in methylene blue photodegradation was improved from 23% to 43% when Au/Pd-modified TiO2 films were used.

2010-11-01

242

A simple spectrophotometric method for determination of the optical constants and band gap energy of multiple layer TiO2 thin films  

International Nuclear Information System (INIS)

Using sol-gel processing, TiO2 films have been prepared on microscopic glass slides by dip-coating technique. From X-ray diffractometric (XRD) and X-ray photoelectron spectroscopic (XPS) measurements, it has been confirmed that the deposited films are an anatase form of stoichiometric TiO2. Using either normal incidence transmittance or normal incidence reflectance data, a simple method for determining both film refractive index, n(?), and film thickness, d, has been proposed for a transparent film on a non-absorbing flat substrate. At same wavelength within visible region, a correlation between TS and TB has been established and verified. TS and TB represent the transmittances of single side and both sides coated films of same thickness, respectively, prepared at identical conditions. Average film thickness per coating at various withdrawal speeds (58-146 mm min-1) has been estimated. An empirical dispersion equation that describes the variation of n(?) of TiO2 films in the wavelength (?) range of ?390-800 nm has been deduced. Band gap energy (Eg) has also been estimated for these films. It has been observed that Eg changes from ?3.35 to 3.16 eV as the film thickness varies from ?100 to 300 nm and it does not depend significantly upon film withdrawal speeds in the range 58-146 mm min-1

2004-01-15

243

Ultrathin-layer chromatography on SiO(2), Al(2)O(3), TiO(2), and ZrO(2) nanostructured thin films.  

Science.gov (United States)

We explored four different inorganic oxides and determined their merits in miniaturized planar chromatography. Despite progression of chromatographic techniques over several decades, such alternatives to traditional planar silica gel stationary phases have not been fully evaluated. Glancing angle deposition(GLAD) provided an excellent platform for engineering nanostructured thin films in these materials for ultrathin-layer chromatography (UTLC). Separations of carotenoids and synthetic food dyes were used to investigate the attributes of SiO(2), Al(2)O(3), TiO(2), and ZrO(2)GLAD UTLC media. These anisotropic high surface area thin films possessed similar channel-like features but different chromatographic properties.TiO(2)and ZrO(2)media were especially interesting since analyte retention could be modified through sim-ple oxidation heat treatments and UV irradiation. Generally, oxidation reduced analyte retention while UV exposure increased retention. Changes in retention factor as large as ?hRF? 40 (for Acid Red 14 on titanium oxide) were achieved. Food dye mixtures were applied using consumer inkjet printers as per the Office Chromatography concept and separation performance was quantified using advanced video instrumentation designed for miniaturized plates. Enhanced time-resolved UTLC methods were used to calculate figures of merit from recorded dye separation videos. Small theoretical plate heights (<4 ?m)and low limits of detection (<2 ng per zone for the food dye tartrazine) were measured. The combination of engineered GLAD UTLC plates, inkjet application of analyte spots, time-resolved UTLC, and custom analysis algorithms enabled some of the best performance achieved on GLAD UTLC layers. Separations on the inorganic oxide thin films were also successfully hyphenated with electrospray ionization mass spectrometry for the first time. This investigation demonstrates the utility of alternative inorganic oxide GLADUTLC media and probes avenues of expanding the capabilities of miniaturized planar chromatography. PMID:24354005

Wannenmacher, Julia; Jim, Steven R; Taschuk, Michael T; Brett, Michael J; Morlock, Gertrud E

2013-11-29

244

TiO2/Au/TiO2 multilayer thin films: Novel metal-based transparent conductors for electrochromic devices  

International Nuclear Information System (INIS)

Transparent conductors based on Au films, with thicknesses in the 2.6 8 nm, as seen from electron microscopy, electrical resistance, and spectrophotometric transmittance and reflectance. Optical data for uniform films were given a consistent interpretation within the Drude model. Optimized TiO2/Au/TiO2 films, with a luminous transmittance of 80%, were found to have good electrochemical durability and may be useful for applications in electrochromic devices.

2009-12-15

245

Synthesis and Annealing of Nanostructured TiO2 Films by Radio-Frequency Magnetron Sputtering  

Directory of Open Access Journals (Sweden)

Full Text Available In this investigation, anatase TiO2 thin films were deposited on glass substrates at room temperature by RF magnetron sputtering at an elevated sputtering pressure of 3 Pa. The TiO2 films deposited at room temperature were annealed at different temperatures up to 873°K for 1 h. The TiO2 films were characterized by X-Ray Diffraction (XRD, Field-Emission Scanning Electron Microscopy (FESEM, Atomic Force Microscopy (AFM and UV-visible-NIR spectrophotometry. The XRD results reveal that the as-deposited film possess the anatase structure. Annealed TiO2 films show an insignificant change in crystallinity except of the fact that there is a slight increase for the film annealed at 600°C. The crystallite size increases from 44.5 to 48 nm with the increase of the annealing temperature. As-grown TiO2 film exhibits high visible transmittance with enhanced refractive index of 2.31 at a wavelength of 550 nm. The indirect optical band gaps of the as-deposited and annealed films have been estimated to be in the range of 3.39-3.42 eV. AFM observations reveal the compact and dense morphology of the as-deposited and annealed TiO2 thin films.

M.M. Hasan

2009-01-01

246

Poly(vinyl chloride)-g-poly(2-(dimethylamino)ethyl methacrylate) graft copolymers templated synthesis of mesoporous TiO2 thin films for dye-sensitized solar cells  

International Nuclear Information System (INIS)

A poly(vinyl chloride) (PVC) main chain was grafted with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) containing a quaternary amine group using atom transfer radical polymerization. The successful synthesis of a PVC-g-PDMAEMA graft copolymer was confirmed by Fourier transform infrared, nuclear magnetic resonance, thermogravimetric analysis, and transmission electron microscopy. The PVC-g-PDMAEMA graft copolymer was used as a structure-directing agent (SDA) for the fabrication of a mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of SDA to TTIP as well as the concentration of the sol–gel was varied. The structure and porosity of the mesoporous film were characterized by XRD and SEM analysis. The mesoporous TiO2 film fabricated on the FTO surface was used as a photoanode for the dye-sensitized solar cell (DSSC). DSSC performance was the greatest when using TiO2 film with a higher porosity and lower interfacial resistance. The highest energy conversion efficiency reached 3.2 % at 100 mW/cm2, which was one of the highest reported values for a quasi-solid-state DSSC with 600-nm-thick TiO2 film.

2012-07-01

247

Preparation of regularly structured nanotubular TiO2 thin films on ITO and their modification with thin ALD-grown layers  

International Nuclear Information System (INIS)

Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films. (paper)

2012-03-30

248

Morphology control of cathodically deposited TiO2 films  

International Nuclear Information System (INIS)

This work demonstrates that the microstructure of TiO2 film can be designed and controlled by adjusting the temperature and cycle number of cathodic deposition in a solution containing TiCl3 and NaNO3. The redox interactions between TiCl3 and NO3- are investigated by in situ ultraviolet-visible (UV-vis) absorption spectroscopy. Linear sweep voltammetry (LSV) is employed to study the NO3- reduction and to clarify the deposition behavior of TiO2 in the designed plating solution. The decrease in TiO2 deposition rate with the TiO2 thickness may be due to the poor electron conductivity of TiO2 depressing the generation rate of OH- from the NO3- reduction. The morphology and size of TiO2 aggregates are strongly influenced by varying the deposition temperature from 5 to 50 oC and a maximal rate of TiO2 deposition is obtained at 25-35 oC. TiO2 deposited at 25 oC is the roughest with a roughness factor (Ra) of ca. 67 nm. This study provides a useful method to control the morphology and deposition rate of TiO2 film for practical photoelectrochemical applications.

2010-09-30

249

Investigation of a broadband TiO2/SiO2 optical thin-film filter for hybrid solar power systems  

International Nuclear Information System (INIS)

Highlights: ? We present a new optical filter to get optimal performance of PV power system. ? The experimental results of the filter fabrication match well with numerical design. ? The measured results of a typical Si cell show efficiency increase using the filter. ? A proposed model for hybrid PV–TEG system demonstrates the benefits of the filter. -- Abstract: Using the technology of spectral selectivity to integrate different solar power generators in a hybrid system is a feasible way to improve the optical-electric efficiency. This paper presents an 82-layer broadband optical interference thin-film filter matching with crystalline silicon photovoltaic cells, which using TiO2 and SiO2 as fabrication materials and can be used in hybrid solar power systems like photovoltaic–thermoelectric generator (PV–TEG) systems. The design, optimization and fabrication process of the filter is described, high reflectance from 400 nm to 1100 nm as well as high transmittance from 1100 nm to 2500 nm over the broadband of solar spectrum are obtained. The classical electron beam evaporation plant is used to fabricate the filter. Four different incidence angles’ optical performances of the sample filter are measured which agree well with the numerical simulation results. The electrical characteristics of a typical Silicon photovoltaic cell using the fabricated sample filter are measured. An average efficiency increase of 3.24% for the solar cell with respect to the solar energy it receives can be obtained due to the filter. A calculation model for a hybrid PV–TEG system using this thin-film filter is proposed and the benefits of the filter for hybrid solar power systems are demonstrated.

2012-04-01

250

Tin-diffused glass slab waveguides locally covered with tapered thin TiO2 films for application as a polarimetric interference sensor with an improved performance.  

Science.gov (United States)

Common soda lime slide glass substrates made by floating molten glass on the surface of molten tin contain a tin-diffused layer that is demonstrated to be a low-loss polarization-insensitive slab optical waveguide. In this study, such a tin-diffused waveguide was locally covered with a tapered thin TiO2 film to form a composite structure in which the zeroth-order transverse electric (TE0) and magnetic (TM0) modes are spatially separated from each other. This feature enables the composite structure to serve as a highly sensitive polarimetric interferometer. Moreover, a negligible modal birefringence of tin-diffused waveguides offers the polarimetric interferometer an improved performance relative to those fabricated earlier using single-mode potassium ion-exchanged glass waveguides. In situ detection of both the protein adsorption and a small change in refractive index of liquid was accomplished using the tin-diffused waveguide-based polarimetric interferometer. With horse heart myoglobin, adsorption from aqueous solution less than 0.125 monolayer coverage can cause the interferometer to yield a phase-difference change of delta phi = 2pi. PMID:15859000

Qi, Zhi-mei; Honma, Itaru; Zhou, Haoshen

2005-02-15

251

Nanoscale oxygen nonstoichiometry in epitaxial TiO2 films grown by pulsed laser deposition  

Science.gov (United States)

Nanoscale control of oxygen nonstoichiometry in oxide thin films has become more and more important as the characteristic sizes of oxide devices have been reduced to the nanometer scale. We propose a new in situ electrochemical approach for nanoscale characterization of oxygen stoichiometry in epitaxial oxide thin films. For this purpose, we have developed a pulsed laser deposition system equipped with an electrochemical analysis cell. In situ characterization of homoepitaxial TiO2 thin films by a combination of reflection high-energy electron diffraction and Mott-Schottky analysis has revealed that the lattice oxygen in the TiO2 film subsurface region up to a depth of about 10 nm can be easily lost or gained, depending on temperature and the ambient oxygen pressure. This unavoidably results in a nanoscale inhomogeneous distribution of oxygen vacancies in TiO2 films.

Takata, Shintaro; Tanaka, Ryohei; Hachiya, Atsushi; Matsumoto, Yuji

2011-11-01

252

A corrosion-resistance superhydrophobic TiO2 film  

International Nuclear Information System (INIS)

A superhydrophobic TiO2 film with water contact angle greater than 170° on Hastelloy substrate was fabricated through simply dip-coating method from TiO2 precursor solution containing TiO2 nanoparticles with the average diameter 25 nm, followed by heat-treatment and modification with fluoroalkylsilane (FAS) molecules. The as-obtained sample was characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement respectively. Moreover, the dynamic light scattering (DLS) size distribution of TiO2 aggregated particles in the TiO2 precursor solution containing P25 particles was evaluated by Laser Particle Sizer. It is found that the TiO2 nanoparticles in TiO2 precursor solution play a crucial role to form high superhydrophobicity. Simultaneously, the superhydrophobic TiO2 film still showed great superhydrophobicity after corroded with strong acid or alkali solutions and protected the substrate from corrosion which should be critical to the potential application in industry.

2012-07-15

253

Deposition of a thin film of TiOx from a titanium metal target as novel blocking layers at conducting glass/TiO2 interfaces in ionic liquid mesoscopic TiO2 dye-sensitized solar cells.  

Science.gov (United States)

In dye-sensitized TiO2 solar cells, charge recombination processes at interfaces between fluorine-doped tin oxide (FTO), TiO2, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. From this point of view, a high work function material such as titanium deposited by sputtering on FTO has been investigated as an effective blocking layer for preventing electron leakage from FTO without influencing electron injection. X-ray photoelectron spectroscopy analysis indicates that different species of Ti (Ti4+, Ti3+, Ti2+, and a small amount of Ti0) exist on FTO. Electrochemical and photoelectrochemical measurements reveal that thin films of titanium species, expressed as TiOx, work as a compact blocking layer between FTO and TiO2 nanocrystaline film, improving Voc and the fill factor, finally giving a better conversion efficiency for dye-sensitized TiO2 solar cells with ionic liquid electrolytes. PMID:17165966

Xia, Jiangbin; Masaki, Naruhiko; Jiang, Kejian; Yanagida, Shozo

2006-12-21

254

Heterogeneous photocatalytic decomposition of benzene on lanthanum-doped TiO2 film at ambient temperature.  

Science.gov (United States)

Lanthanum-doped anatase TiO2 thin films on glass prepared via a sol-gel process have been shown to have much higher photocatalytic activity for the degradation of gaseous benzene than pure anatase TiO2 thin film. The photodecomposition of benzene on both types of TiO2 films follows the first-order kinetics while the CO(2) and CO formation followed the zero-order kinetics. GC/MS identification of the intermediates produced during the photodegradation of benzene revealed that doping lanthanum into TiO2 thin film favors a cleavage of benzene ring. An optimal lanthanum amount with respect to photocatalytic activity was about 2.5 wt% (La2O3/TiO2). PMID:16814365

Zhang, Shicheng; Zheng, Zhijian; Wang, Jinhe; Chen, Jianmin

2006-12-01

255

TiN and TiO2:Nb thin film preparation using hollow cathode sputtering with application to solar cells  

International Nuclear Information System (INIS)

Titanium nitride (TiN) is well known for its excellent conductivity, inertness, and good optical reflectivity at long wavelengths. These properties make it a potential IR-reflective back contact material suitable for ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. Using a pulsed power, 12 cm linear hollow cathode source fitted with Ti targets and with N2 as the reactive gas, TiN films were deposited on Mo-coated glass. The static deposition rate was 50 nm/min for a sputtering power of only 500 W. The high deposition rate indicates the advantage of the reactive environment, hollow cathode sputtering method, i.e., the reactive gas is excluded from the target. Electrical, optical, and physical properties of the films were measured. Resistivities in the range of 50-60 ?? cm were achieved. Reflectance and x-ray diffraction measurements were conducted, and the effects of deposition parameters such as substrate bias and substrate temperature were studied. The optical emission from N and Ti atoms in the plasma was also studied. CIGS solar cells were successfully fabricated on TiN and a conversion efficiency of 12.3% was achieved. Transparent and moderately conductive TiO2 films doped with Nb were also prepared. The electrical and optical properties of these films are reported, and the reflectance of a-Si solar cells was reduced via incorporation of a TiO2:Nb layer

2006-07-01

256

Silver Doped TiO2 Nanostructure Composite Photocatalyst Film Synthesized by Sol-Gel Spin and Dip Coating Technique on Glass  

Digital Repository Infrastructure Vision for European Research (DRIVER)

New composite films (P25SGF-MC-Ag, MPC500SGF-MC-Ag, and ANPSGF-MC-Ag) have been synthesized by a modified sol-gel method using different particle sizes of TiO2 powder and silver addition. Nanostructure TiO2/Ag composite thin films were prepared by a sol-gel spin and dip coating technique. while, by introducing methyl cellulose (MC) porous, TiO2/Ag films were obtained after calcining at a temperature of 500Co. The as-prepared TiO2 and TiO2/Ag films were characterized by X-ray diffractometr...

Mojtaba Nasr-Esfahani; Mohammad Hossein Habibi

2008-01-01

257

Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO 2 / ZrO 2 films  

Directory of Open Access Journals (Sweden)

Full Text Available Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements. Enhancing of photocatalytic activity of zirconia-doped films relative to pure TiO 2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO 2 and TiO 2 / ZrO 2 ( 5 –50% of ZrO 2 films in the processes of Cr VI to Cr III photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples.

2006-01-01

258

Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO2/ZrO2 films  

Directory of Open Access Journals (Sweden)

Full Text Available Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin film photocatalysts were fabricated by sol-gel technique, using nonionic amphiphilic block copolymer Pluronic P123 as template. The structural and optical properties of these films were characterized using SEM, low-angle XRD, and UV/Vis spectroscopy, hexane adsorption investigation. Band gap energy and the position of flatband potentials were estimated by photoelectrochemical measurements. Enhancing of photocatalytic activity of zirconia-doped films relative to pure TiO2 originates from an anodic shift of the valence band edge potential. Catalytic activity of mesoporous TiO2 and TiO2/ZrO2 (5–50% of ZrO2 films in the processes of CrVI to CrIII photoreduction and 2,4-dinitroaniline photooxidation correlates with crystalline size and growth with increasing of specific surface area of the samples.

Olga Linyucheva

2006-02-01

259

Enhanced visible light absorption by TiO2 film patterned with Ag nanoparticles arrays  

Science.gov (United States)

Well patterned Ag nanoparticle (NP) arrays were fabricated on TiO2 thin film (TF). Scanning electron microscopy shows Ag NPs distribution on the TiO2 TF surface. The overall Raman scattering intensity increased for the Ag/TiO2 TF system. The enhanced Raman scattering of Ag/TiO2 TF was due to the formation of strong electromagnetic field around the Ag NPs under photon excitation. Optical absorption measurement shows three times enhancement in visible light absorption for the Ag NPs containing samples as compared to bare TiO2 TF. The photoluminescence emission intensity from the Ag NPs/TiO2 TF sample reduced due to the formation of Ag-O complex on the TiO2 surface.

Ganguly, Aparna; Mondal, Aniruddha; Dhar, Jay Chandra; Singh, Naorem Khelchand; Choudhury, Sushabhan

2013-12-01

260

Double light-scattering layer film based on TiO2 hollow spheres and TiO2 nanosheets: Improved efficiency in dye-sensitized solar cells  

International Nuclear Information System (INIS)

Highlights: ? A novel TiO2 double-layer composite film is successfully fabricated. ? The TiO2-hollow spheres overlayer exhibited intense scattering ability. ? The TiO2-nanosheets underlayer can enlarge the contact area and increase the contact points between TiO2 photoelectrode and FTO glass. ? TiO2-double light-scattering layer film cells have the maximum conversion efficiency. -- Abstract: A novel TiO2 double light-scattering layer (TiO2-DLL) film consisting of TiO2 hollow spheres (TiO2-HS) as overlayer and TiO2 nanosheets (TiO2-NS) as underlayer was designed as the photoelectrode of dye-sensitized solar cells (DSSCs). The photoelectric conversion performances of DSSCs based on TiO2-HS film, TiO2-NS film, and TiO2-DLL film were investigated. It was found that the TiO2-DLL film cell achieved the highest conversion efficiency and reached up to a maximum value of 5.08%, which is 23.3% higher than that of TiO2-HS film cell (? = 3.62%) and 8.3% higher than that of TiO2-NS film cell (? = 4.31%) under identical film thickness at a constant irradiation of 100 mW cm?2. The enhanced efficiency of TiO2-DLL film can be attributed to its relatively high specific surface area and enhanced light-scattering capability. Furthermore, the TiO2-NS underlayer ensures good electronic contact between TiO2 film and the F-doped tin oxide (FTO) conducting glass

2013-10-25

 
 
 
 
261

Characterisation of samarium and nitrogen co-doped TiO2 films prepared by chemical spray pyrolysis  

International Nuclear Information System (INIS)

Highlights: ? The TiO2:N:Sm thin films deposited by chemical spray pyrolysis have anatase structure. ? According to XPS, N is incorporated into the TiO2 matrix. ? N-doping increases and Sm-doping reduces the crystallite size of the TiO2:N:Sm films. ? Incorporation of N strongly suppresses the Sm3+ PL emission. - Abstract: The sol–gel chemical spray pyrolysis method was used to deposit samarium and nitrogen co-doped TiO2 films onto a quartz substrate at a growth temperature of 450 °C using pulsed spray solution feed, followed by annealing at 500 °C for 2 h in air. The obtained films exhibited anatase structure independent of the doping level. According to XRD analysis, the mean crystallite size of the undoped TiO2, TiO2:N(25) and TiO2:N(5):Sm(5) films was 32, 38 and 20 nm, respectively. According to AFM, the undoped TiO2 film consisted of agglomerates with a size of 30–200 nm. N-doping (25 at%) transformed the agglomerates into individually distinctive grains with a size of ca. 30 nm, while Sm doping (5 at%) caused a significant decrease in the average diameter of the agglomerates to ca. 100 nm. The RMS roughness of the undoped TiO2 film was 1.7 nm; doping resulted in the formation of smoother films with RMS roughness of 0.9–1.4 nm. XPS data indicated that the Sm and N dopants were incorporated into the TiO2 crystal lattice and/or adsorbed on the surface of the film. An increasing nitrogen concentration in the spray solution correlates to a systematic suppressing of the photoluminescence intensity of Sm3+.

2012-11-15

262

Thermal properties of TiO2 films grown by atomic layer deposition  

International Nuclear Information System (INIS)

We study the thermal properties of amorphous TiO2 thin films of various thicknesses t, grown by atomic layer deposition. The thermo-optic coefficient dn/dT and the temperature coefficient d?/dT of film density ? are determined from ellipsometric data in wavelength range 380 ?5 °C?1 and d?/dT = ? 4.8 × 10?5g cm?3° C?1. - Highlights: ? We study thermal properties of TiO2 films grown by atomic layer deposition (ALD). ? dn/dT is negative for thin films and takes positive values for relatively thicker ones. ? Films are denser than ones grown by other techniques such as evaporation.

2012-06-01

263

TiO2/polyaniline nanocomposite films prepared by magnetron sputtering combined with plasma polymerization process  

International Nuclear Information System (INIS)

Radiofrequency plasma polymerization in combination with direct current reactive magnetron sputtering is utilized for the synthesis of TiO2/plasma polymerized aniline nanocomposite thin films. In the composite film, X-ray diffraction measurements reveal formation of nanocrystalline rutile TiO2 of crystallite size 3.6 nm. Due to continuous bombardment of plasma species during simultaneous magnetron sputtering and plasma polymerization, the precursors of polymerization are broken and few functional groups are retained in the composite film. The plasma polymerized aniline has the direct optical band gap of 3.55 eV and the nanocrystalline rutile TiO2 is wide gap semiconductor with indirect gap of 3.20 eV which suggests the existence of an energy barrier at the interface in the composite form. The ac conductivity of composite film shows significant improvement as compared to plasma polymerized aniline film and sputtered rutile TiO2 film. The composite film may find potential application as antistatic coatings.

2011-11-15

264

Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island  

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In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron...

Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

2012-01-01

265

Dye-sensitized solar cells with TiO2 nanocrystalline films prepared by conventional and rapid thermal annealing processes  

International Nuclear Information System (INIS)

Titanium oxide (TiO2) thin films are prepared by the sol-gel method and annealed at 600 oC by conventional (CTA) and rapid thermal annealing (RTA) processes on fluorine-doped tin oxide-coated glass substrates for application as the work electrode for the dye-sensitized solar cells (DSSC). TiO2 thin films are crystallized using a conventional furnace and the proposed RTA process at annealing rates of 5 oCmin-1 and 600 oCmin-1, respectively. The TiO2 thin films are characterized by X-ray diffraction, scanning electron microscopy and Brunauer-Emmett-Teller analysis. Based on the results, the TiO2 films crystallized by RTA show better crystallization, higher porosity and larger surface area than those of CTA. The short-circuit photocurrent and open-circuit voltage values increased from 5.2 mAcm-2 and 0.6 V for the DSSC with the CTA-derived TiO2 films to 8.3 mAcm-2 and 0.68 V, respectively, for the DSSC containing RTA-derived TiO2 films.

2011-03-01

266

Ion-beam modification of TiO2 film to multilayered photocatalyst  

International Nuclear Information System (INIS)

We report a dry process to produce a multilayered TiO2 film which has the rutile phase on an anatase substrate, for highly activated photocatalysis. Ar ion beam irradiation changes the anatase surface into rutile at 500 deg. C, which is less than the crystallization temperature of rutile from anatase (600 deg. C). The ion beam modification makes it possible to form rutile thin film on anatase. The multilayered structure should be a promising photocatalyst, theoretically

1999-01-02

267

Wet Etching of TiO2-Based Precursor Amorphous Films for Transparent Electrodes  

Science.gov (United States)

We investigated wet etching of Nb-doped anatase TiO2 (TNO) transparent conducting thin films and their precursors in an amorphous phase deposited by rf sputtering on glass substrates. The polycrystalline TNO films showed a very low etching rate of less than 0.06 nm/min in concentrated sulfuric acid (H2SO4) even at elevated temperatures up to 95 °C. In contrast, H2SO4 etched the precursor films at a rate of 1.4 nm/min at 95 °C. The etching rate of the amorphous films followed the Arrhenius equation, leading us to conjecture that a much higher etching rate of ˜230 nm/min can be achieved at 170 °C. These results indicate that wet-etching of precursor amorphous films prior to crystallization represents a practical and low-cost lithographic technique for patterning TiO2-based transparent electrodes.

Ohkubo, Junpei; Hirose, Yasushi; Sakai, Enju; Nakao, Shoichiro; Hitosugi, Taro; Hasegawa, Tetsuya

2011-01-01

268

Third-generation biosensors based on TiO2 nanostructured films  

International Nuclear Information System (INIS)

The functionalisation of solid electrodes with thin films of biocompatible materials revealed very attractive for the development of biosensors on miniaturized platforms, since this configuration could provide a rapid translation of the biological processes occurring on the surface to electronic outputs. In this study, the realization of functionalised TiO2 thin films on Si substrates for the immobilization of several enzymes and biological molecules is reported. Deposition parameters were found to affect the chemical and microstructural features of the films, which influenced the protein immobilization. Glucose oxidase and horseradish peroxidase immobilized onto TiO2-based nanostructured surfaces exhibited a pair of well-defined and quasi-reversible voltammetric peaks. The electron exchange between the enzyme and the electrodes was greatly enhanced in the TiO2 nanostructured environment. The electrocatalytic activity of HRP and GOD embedded in TiO2 electrodes toward H2O2 and glucose, respectively, may have a potential perspective in the fabrication of third-generation biosensors based on direct electrochemistry of enzymes

2006-07-01

269

Preparation and characterization of whey protein film incorporated with TiO2 nanoparticles.  

Science.gov (United States)

Biodegradable titanium dioxide (TiO(2))/whey protein isolate (WPI) blend films were made by casting denatured WPI film solutions incorporated with TiO(2) nanoparticles. X-ray diffraction, UV-vis spectra, and fluorescence spectra of the films showed the successful incorporation of TiO(2) nanoparticles into the WPI matrix and indicated the interactions between TiO(2) and WPI. Mechanical tests revealed the antiplasticizing effect of TiO(2) nanoparticles on the WPI/TiO(2) film. Small amounts (1 wt%) of TiO(2) improves moisture barrier properties but lowers the tensile properties of the film. Microstructural evaluation confirmed the aggregation and distribution of TiO(2) nanoparticles within the WPI matrix and validated the results of functional properties of the WPI/TiO(2) film. PMID:19895492

Zhou, J J; Wang, S Y; Gunasekaran, S

2009-09-01

270

p-NITROPHENOL PHOTOCATALYSIS ON NANOSTRUCTURED TiO2 FILMS  

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The photocatalytic activity of supported TiO2 nanostructures (nanotubes and nanoparticles) was evaluated kinetically during the p-nitrophenol oxidation. The results were compared with those obtained using nanoparticles in suspension and a thin film of catalyst respectively. The nanotubes were synthesized electrochemically by titanium anodization in HF electrolyte; the nanoparticles were synthesized in microemulsion by TiCl4 chemical oxidation. The degradation was carried out in a flow reactio...

2011-01-01

271

The resistive switching in TiO2 films studied by conductive atomic force microscopy and Kelvin probe force microscopy  

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Full Text Available The resistive switching characteristics of TiO2 thin films were investigated using conductive atomic force microscopy (CAFM and Kelvin probe force microscopy (KPFM. The as-prepared TiO2 thin films were modulated into higher and lower resistance states by applying a local electric field. We showed that the resistive switching results from charge injection and release assisted by electro-migration of oxygen ions. An integrated model combined with filamentary and interfacial effects was utilized to elucidate the experimentally observed phenomenon.

Yuanmin Du

2013-08-01

272

Enhanced optical properties of sol-gel derived TiO 2 films using microwave irradiation  

Science.gov (United States)

Thin films of TiO 2 have been deposited on polished quartz substrates at room temperature by sol-gel dip coating technique followed two different annealing treatment methods. One set by conventional annealing at 600 °C for 3 h and second set exposure to microwave (2.45 GHz) radiation at 600 W power for 10 min. X-ray diffraction and scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-visible spectroscopy, techniques have been employed to characterize structural, morphological, compositional and optical properties of the microwave exposed and annealed films. Both microwave exposed and annealed films have shown the nanostructured growth of TiO 2 anatase phase with grain size ranging from 10 nm to 25 nm. Due to decrease in the grain size there was a blue shift of Eg calculated in direct transition. Refractive index of the film annealed has shown higher value compared to microwave exposed films. Plausible mechanism for the formation of anatase phase of TiO 2 on quartz substrates has also been discussed.

Di Claudio, D.; Phani, A. R.; Santucci, S.

2007-10-01

273

Influence of ZnFe2O4 doping on the structural and optical properties of TiO2 films  

Science.gov (United States)

Amorphous TiO2 thin films with and without the doping of ZnFe2O4 were prepared by radio frequency magnetron sputtering. The influence of post-deposition annealing on the structural and optical properties was studied. It was established that the anatase single phase exists between 250 degree(s)C and 800 degree(s)C in the TiO2 thin films, and between 450 degree(s)C and 650 degree(s)C in the TiO2 thin films with 2 wt% doping of ZnFe2O4. The absorption edge of TiO2 thin films with and without doping exhibits a blue shift with decreasing annealing temperature and the absorption edge of TiO2 doped with ZnFe2O4 has moved to visible spectrum range. The enhanced photoluminescence of the TiO2 films doped with ZnFe2O4 was found in comparison with pure TiO2 thin films at room temperature.

Li, Guanghai; Yang, Lin; Zhang, Lide

2000-11-01

274

Enhanced performance of dye-sensitized solar cell via surface modification of mesoporous TiO2 photoanode with electrodeposited thin TiO2 layer  

International Nuclear Information System (INIS)

Highlights: ? TiO2-modified photoanode composed of compact underlayer and efficient electron transport network was fabricated directly by anodic electrodeposition in an aqueous TiCl3 electrolyte. ? The electrodeposited thin TiO2 layer could bridge gaps between TiO2 nanoparticles and improve the electrical contact at the FTO/TiO2 interface, leading to an efficient electron transport. ? The electrodeposited compact TiO2 layer could cover the exposed surface area of FTO to the electrolyte, which contributes to the suppression of the charge recombination. ? We demonstrated that the TiO2-modified photoanode significantly enhances the photovoltaic properties of the DSSC compared to the bare photoanode. - Abstract: Surface modification of porous TiO2 photoanode with a thin compact TiO2 layer was carried out by means of anodic electrodeposition in an aqueous TiCl3 electrolyte. Results indicated that the electrodeposited thin TiO2 layer could bridge gaps between TiO2 nanoparticles and improve the electrical contact at the FTO (fluoride-doped tin oxide)/TiO2 interface, leading to an efficient electron transport. In addition, the thin compact TiO2 layer could cover the exposed surface area of FTO to the electrolyte, which contributes to the suppression of the charge recombination. The surface treatment of mesoporous TiO2 photoanode via aqueous electrochemical route is an effective way to improve the performance of DSSC (dye-sensitized solar cell), which could increase the short-circuit current density, and reduce the dark current density compared to DSSCs with bare and TiCl4-treated TiO2 photoanodes. The photoelectron conversion efficiency of DSSC was increased from 7.3 to 8.2% after employing the TiO2-modified photoanode.

2011-10-01

275

Influence of process parameters on the growth of pure-phase anatase and rutile TiO2 thin films deposited by low temperature reactive magnetron sputtering  

International Nuclear Information System (INIS)

In this work is investigated the optimal conditions for deposition of pure-phase anatase and rutile thin films prepared at low temperatures (less than 150 deg C) by reactive dc magnetron sputtering onto well-cleaned p-type Si substrates. For this, the variation of deposition plasma parameters as substrate-to-target distance, total gas pressure, oxygen concentration, and substrate bias were studied and correlated with the characteristics of the deposited films. The XRD analysis indicates the formation of pure rutile phase when the substrate is biased at voltages between -200 and -300 V. Pure anatase phase is only attained when the total pressure is higher than 0.7 Pa. Moreover, it is noticeable a strong dependence of surface roughness with parameters studied. (author)

2010-09-01

276

Influence of High-energy electron-beam on photocatalytic activity of TiO2 films on carbon-fiber deposited by atomic layer deposition  

International Nuclear Information System (INIS)

High-energy electron-beam with energy of 1 MeV was used for modifying surface structure of TiO2 thin films on carbon fiber prepared by using atomic layer deposition under atmospheric pressure. TiO2 nanoparticles (?20 nm) on carbon fiber underwent structural modification of the surface upon electron-beam treatment, resulting in enhanced photocatalytic activity. In contrast, a thicker film of TiO2 did not show such changes in surface structure and photocatalytic activity by electron-beam treatment. We demonstrate that electron-beam can be used for modifying surface structure of photocatalysts consisting of nanoparticles for improvement of their activity. - Highlights: ? Electron-beam was used for modifying surface of TiO2 on carbon fiber. ? TiO2 with various structures were prepared by atomic layer deposition. ? Photocatalytic activity of TiO2/carbon was enhanced by e-beam.

2012-03-01

277

Unusual photoelectric behaviors of Mo-doped TiO2 multilayer thin films prepared by RF magnetron co-sputtering: effect of barrier tunneling on internal charge transfer  

Science.gov (United States)

Mo-doped TiO2 multilayer thin films were prepared by RF magnetron co-sputtering. Microstructures, crystallite parameters and the absorption band were investigated with atomic force microscopy, X-ray diffraction and ultraviolet-visible spectroscopy. Internal carrier transport characteristics and the photoelectric property of different layer-assemble modes were examined on an electrochemical workstation under visible light. The result indicates that the double-layer structure with an undoped surface layer demonstrated a red-shifted absorption edge and a much stronger photocurrent compared to the uniformly doped sample, signifying that the electric field implanted at the interface between particles in different layers accelerated internal charge transfer effectively. However, a heavily doped layer implanted at the bottom of the three-layer film merely brought about negative effects on the photoelectric property, mainly because of the Schottky junction existing above the substrate. Nevertheless, this obstacle was successfully eliminated by raising the Mo concentration to 1020 cm-3, where the thickness of the depletion layer fell into the order of angstroms and the tunneling coefficient manifested a dramatic increase. Under this circumstance, the Schottky junction disappeared and the strongest photocurrent was observed in the three-layer film.

Yan, B. X.; Luo, S. Y.; Mao, X. G.; Shen, J.; Zhou, Q. F.

2013-01-01

278

Atomic layer deposition of TiO2 on surface modified nanoporous low-k films.  

Science.gov (United States)

This paper explores the effects of different plasma treatments on low dielectric constant (low-k) materials and the consequences for the growth behavior of atomic layer deposition (ALD) on these modified substrates. An O2 and a He/H2 plasma treatment were performed on SiCOH low-k films to modify their chemical surface groups. Transmission FTIR and water contact angle (WCA) analysis showed that the O2 plasma changed the hydrophobic surface completely into a hydrophilic surface, while the He/H2 plasma changed it only partially. In a next step, in situ X-ray fluorescence (XRF), ellipsometric porosimetry (EP), and Rutherford backscattering spectroscopy (RBS) were used to characterize ALD growth of TiO2 on these substrates. The initial growth of TiO2 was found to be inhibited in the original low-k film containing only Si-CH3 surface groups, while immediate growth was observed in the hydrophilic O2 plasma treated film. The latter film was uniformly filled with TiO2 after 8 ALD cycles, while pore filling was delayed to 17 ALD cycles in the hydrophobic film. For the He/H2 plasma treated film, containing both Si-OH and Si-CH3 groups, the in situ XRF data showed that TiO2 could no longer be deposited in the He/H2 plasma treated film after 8 ALD cycles, while EP measurements revealed a remaining porosity. This can be explained by the faster deposition of TiO2 in the hydrophilic top part of the film than in the hydrophobic bulk which leaves the bulk porous, as confirmed by RBS depth profiling. The outcome of this research is not only of interest for the development of advanced interconnects in ULSI technology, but also demonstrates that ALD combined with RBS analysis is a handy approach to analyze the modifications induced by a plasma treatment on a nanoporous thin film. PMID:24000800

Levrau, Elisabeth; Devloo-Casier, Kilian; Dendooven, Jolien; Ludwig, Karl F; Verdonck, Patrick; Meersschaut, Johan; Baklanov, Mikhail R; Detavernier, Christophe

2013-10-01

279

Shifting to the red the absorption edge in TiO2 films: a photoacoustic study  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in english When Titanium dioxide in contact with a polluted water sample is irradiated with ultraviolet light, electron-hole pairs can be generated, which can react with oxygen and water producing free radicals that can degrade the pollutants, changing them into harmless compounds for the environment. The ultr [...] aviolet component of the solar radiation is around 7%. Therefore, it is convenient to modify the TiO2 films crystalline structure for obtaining photocatalytical processes with visible light. In this work we report on the growth of TiO2 thin films by the Sol-gel technique considering the incorporation of AgNO3 in the initial solution containing the precursor. The concentration of the AgNO3 saline solution was changed between 5 and 30% to control the grain size of the grown TiO2 nanocrystals, impregnating 6 layers over glass slide substrates and using a sintering temperature of 600 °C. The obtained films were characterized structurally by means of X-ray diffraction. The shift in the forbidden energy bandwidth value to the red part of the optical absorption spectrum was evidenced by Photoacoustic Spectroscopy. The photocatalytic activity was tested on a solution of methylene blue using also the Photoacoustic technique.

F., Gordillo-Delgado; K., Villa-Gómez; E, Marín.

280

Photoconductivity studies on nanoporous TiO2/dopamine films prepared by sol-gel method  

Science.gov (United States)

Dopamine was encapsulated into nanoporous amorphous TiO2 matrix by sol-gel method under atmospheric conditions. A second sample was obtained by the addition of the crown-ether 15C5 in this previous sample. Thin films were spin-coated on glass wafers. No heat treatment was employed in both films. All films were characterized using infrared spectroscopy, high resolution transmission electronic microscopy, X-ray diffraction, optical absorption and scanning electronic microscopy. Despite the films prepared with 15C5 were no calcined, a partial crystallization was identified. Anatase and rutile nanoparticles with sizes of 4-5 nm were obtained. Photoconductivity technique was used to determine the charge transport mechanism on these films. Experimental data were fitted with straight lines at darkness and under illumination wavelengths at 320, 400, and 515 nm. It indicates an ohmic behavior. Photovoltaic and photoconductivity parameters were determined from the current density vs. the applied-electrical-field results. Amorphous film has bigger photovoltaic and photoconductive parameters than the partially crystalline film. Results observed in the present investigation prove that the nanoporous TiO2 matrix can protect the dopamine inhibiting its chemical instability. This fact modifies the optical, physical and electrical properties of the film, and is intensified when 15C5 is added.

Valverde-Aguilar, G.; Prado-Prone, G.; Vergara-Aragón, P.; Garcia-Macedo, J.; Santiago, Patricia; Rendón, Luis

2013-12-01

 
 
 
 
281

Natural and persistent superhydrophilicity of SiO2/TiO2 and TiO2/SiO2 bi-layer films  

International Nuclear Information System (INIS)

Sol-gel SiO2/TiO2 and TiO2/SiO2 bi-layer films have been deposited from a polymeric SiO2 solution and either a polymeric TiO2 mother solution (MS) or a derived TiO2 crystalline suspension (CS). The chemical and structural properties of MS and CS bi-layer films heat-treated at 500 deg. C have been investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscospy. Water contact angle measurements show that MS SiO2/TiO2 and CS TiO2/SiO2 bi-layer films exhibit a natural superhydrophilicity, but cannot maintain a zero contact angle for a long time over film aging. In contrast, CS SiO2/TiO2 bi-layer films exhibit a natural, persistent, and regenerable superhydrophilicity without the need of UV light. Superhydrophilic properties of bi-layer films are discussed with respect to the nature of the TiO2 single-layer component and arrangement of the bi-layer structure, i.e. TiO2 underlayer or overlayer

2008-01-30

282

The Effect of Film Thickness and TiO2 Content on Film Formation from PS/TiO2 Nano composites Prepared by Dip-Coating Method  

International Nuclear Information System (INIS)

Steady-state fluorescence (SSF) technique in conjunction with UV-visible (UVV) technique and atomic force microscope (AFM) was used for studying film formation from TiO2 covered nano sized polystyrene (PS) latex particles (320 nm). The effects of film thickness and TiO2 content on the film formation and structure properties of PS/TiO2 composites were studied. For this purpose, two different sets of PS films with thicknesses of 5 and 20?m were prepared from pyrene-(P-) labeled PS particles and covered with various layers of TiO2 using dip-coating method. These films were then annealed at elevated temperatures above glass transition temperature (Tg) of PS in the range of 100-280 degree C. Fluorescence emission intensity, Ip from P and transmitted light intensity, Itr were measured after each annealing step to monitor the stages of film formation. The results showed that film formation from PS latexes occurs on the top surface of PS/TiO2 composites and thus developed independent of TiO2 content for both film sets. But the surface morphology of the films was found to vary with both TiO2 content and film thickness. After removal of PS, thin films provide a quite ordered porous structure while thick films showed non porous structure.

2012-01-01

283

Photocatalytic activity enhancement of TiO2 films by micro and nano-structured surface modification  

International Nuclear Information System (INIS)

Titanium oxide thin films were deposited by spin coating using a precursor solution of titanium oxide (IV) acetylacetonate. To increase the contact surface area of the films, TiO2 microspheres were added to the surface of the films. These spheres were 2 ?m in diameter and formed agglomerates on the surface. They did not spread uniformly across the substrate, creating different roughnesses and morphologies along the surface of films. Photocatalytic properties of the samples were tested by the degradation of a methyl orange solution. The degradation performance was compared between plain films, films with microspheres and films covered with commercial TiO2 P25 powder. The results indicate that the samples that were surface modified with TiO2 microspheres present a photodegradation reaction rate 62 times higher than that obtained for plain TiO2 films. The rate of reaction of the samples covered with P25 was 2 times greater than that obtained for the samples with microspheres, but the adhesion to the film was better in the case of microspheres. Moreover, samples with microspheres could be reused several times maintaining the same structural and photocatalytic properties.

2009-04-01

284

Photocatalytic degradation of dimethoate using LbL fabricated TiO2/polymer hybrid films  

International Nuclear Information System (INIS)

Highlights: ? The LbL-TiO2 thin films offer many advantages unlike TiO2 used in powder form. ? TiO2 can be immobilized using low concentrations on polymer on any substrate using a simple method. ? The solution, after the completion of the reaction, can be disposed directly into the environment. ? Degradation of organics is complete with no harmful intermediates being produced in the process. ? Immobilization is inexpensive and catalysts can be reused making it a cost effective method. - Abstract: Degradation of dimethoate under UV irradiation using TiO2/polymer films prepared by the layer-by-layer (LbL) method was investigated. The thin films were fabricated on glass slides and the surface morphology and roughness of the thin films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The effect of lamp intensity, catalyst loading in the layers, number of bilayers, pH and initial dimethoate concentration on the degradation of dimethoate was systematically studied. The degradation was monitored using high performance liquid chromatography (HPLC) analysis and total organic carbon (TOC) measurements as a function of irradiation time, to see the change in concentration of dimethoate and mineralization, respectively. Complete degradation of dimethoate was achieved under TiO2 optimum loading of 4 g/L at an UV irradiation time of 180 min. Increase in the lamp intensity, catalyst loading and number of bilayers increased the rate of degradation. At a pH of 4.62, complete degradation of dimethoate was observed. The degradation efficiency decreased with increase in initial dimethoate concentration. The degradation byproducts were analyzed and confirmed by gas chromatography-mass spectra (GC-MS). Toxicity of the irradiated samples was measured using the luminescence of bacteria Vibrio fischeri after 30 min of incubation and the results showed more toxicity than the parent compound. Catalyst reusability studies revealed that the fabricated thin films could be repeatedly used for up to ten times without affecting the photocatalytic activity of the films. The findings of the present study are very useful for the treatment of wastewaters contaminated with pesticides.

2011-11-15

285

Investigation into the photo-induced change in wettability of hydrophobized TiO2 films  

International Nuclear Information System (INIS)

The photo-induced change in wettability of hydrophobized TiO2 films has been investigated for steel coated with acidic TiO2 nanosols containing varying concentrations of dispersed nanocrystalline titania, such as Degussa P25. The photo-induced change in wettability was evaluated by measuring the time-dependent drop of water contact angle (WCA) after samples had been soaked in either n-octyltriethoxysilane (OTS) or decanoic acid (DA). TiO2 films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 160 deg. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 0 deg. As P25 content and layer thickness increase, high rates of photo-induced change are found, but a moderate calcination regime is required. On the other hand, hardness and E modulus pass through a maximum at 25 wt% P25, so that a P25 content between 25 and 50 wt% is the optimum for practical uses. With such stable coatings, wettability can be controlled over a wide range, and the switch between hydrophobic and hydrophilic states can be carried out repeatedly when DA is used as the hydrophobizing agent. Use of a low calcination temperature (450 deg. C) for the intermediate annealing of the single layers in multilayer coatings and a short final sintering step at a relatively high temperature (e.g. 630 deg. C for 10 min) allow the preparation of relatively thin TiO2 films on steel with a high photoactivity

2008-07-15

286

Photo-induced wettability of TiO2 film with Au buffer layer  

Science.gov (United States)

The effect of thickness of Au buffer layer (15-25 nm) between TiO2 film and substrate on the wettability of TiO2 films is reported. TiO2 films grown on Au buffer layer have a higher contact angle of 96-;100° as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam; Madhurima, V.

2014-04-01

287

A Rapid Method of Assessing the Photocatalytic Activity of Thin TiO2 Films Using an Ink Based on the Redox Dye 2,6-Dichloroindophenol  

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Full Text Available An indicator ink based on the redox dye 2,6-dichloroindophenol (DCIP is described, which allows the rapid assessment of the activity of thin, commercial photocatalytic films, such as Activ. The ink works via a photoreductive mechanism, DCIP being reduced to dihydro-DCIP within ca. 7.5 minutes exposure to UVA irradiation of moderate intensity (ca. 4.8 mW cm−2. The kinetics of photoreduction are found to be independent of the level of dye present in the ink formulation, but are highly sensitive to the level of glycerol. This latter observation may be associated with a solvatochromic effect, whereby the microenvironment in which the dye finds itself and, as a consequence, its reactivity is altered significantly by small changes in the glycerol content. The kinetics of photoreduction also appear linearly dependent on the UVA light intensity with an observed quantum efficiency of ca. 1.8×10−3.

James Hepburn

2008-04-01

288

Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering  

International Nuclear Information System (INIS)

Highlights: ? A simple MAO is used to prepare porous WO3/TiO2 layer on Ti sheet as a visible-light enabled catalyst. ? The photocatalytic activity of the WO3/TiO2 is enhanced by sputtering over an N,C-TiO2 layer. ? This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO2-WO3/TiO2 films with a high surface area using a two-step approach. A porous WO3/TiO2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO2 (N,C-TiO2) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO2 lattice using direct current magnetron sputtering. The resulting microporous TiO2-WO3/TiO2 film with a 0.38-?m-thick N,C-TiO2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO2-WO3/TiO2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO3/TiO2 can be used as a template of hybrid electrode because it enables rapid fabrication.

2012-12-15

289

Photocatalytic Activities of TiO2 and TiO2/Al2O3 Films Coated on Foam Nickel Substrates  

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Full Text Available Anatase TiO2 and TiO2/Al2O3 films were successfully prepared on foam nickel substrates by sol-gel technique. The characteristics and photocatalytic activities of the TiO2 and TiO2/Al2O3 films were investigated by XRD, FE-SEM, etc and by photocatalytic degradation reactions of gaseous acetaldehyde under ultraviolet light irradiation, respectively. The TiO2 and TiO2/Al2O3 films coated on foam nickel substrates display a high photocatalytic activity for the degradation of acetaldehyde. Compared with the onefold TiO2 films coated on foam nickel, the TiO2/Al2O3 films show much higher photocatalytic activities. It is confirmed that photocatalytic activities and stabilities are enhanced by coating Al2O3 as transition layer on foam nickel, which increase the specific surface areas of substrate surface and absorption property, resulting in increase in the photocatalytic activity.

HU Hai,XIAO Wen-Jun,YUAN Jian,SHI Jian-Wei,SHANGGUAN Wen-Feng

2007-03-01

290

Influence of high-energy electron beam on photo catalytic activity of TiO2 films on carbon-fiber deposited by atomic layer deposition  

International Nuclear Information System (INIS)

High energy electron-beam with energy of 1 MeV was used for modifying surface structure of TiO2 thin films on carbon fiber prepared by using atomic layer deposition under atmospheric pressure. TiO2 nanoparticles on carbon fiber underwent structural modification of the surface upon electron-beam treatment, resulting in enhanced photo catalytic activity. In contrast, a thicker film of TiO2 did not show such changes in surface structure and photo catalytic activity by electron-beam treatment. We demonstrate that electron-beam can be used for modifying surface structure of photo catalysts consisting of nanoparticles for improvement of their activity

2011-03-25

291

Polymer Photovoltaic Cell Using TiO2/G-PEDOT Nanocomplex Film as Electrode  

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Using TiO2/G-PEDOT (PEDOT/PSS doped with glycerol) nanocomplex film as a substitute for metal electrode in organic photovoltaic cell is described. Indium tin oxide (ITO) worked as cathode and TiO2/G-PEDOT nanocomplex works as anode. The thickness of TiO2 layer in nanocomplex greatly affects the act of this nonmetallic electrode of the device. To enhance its performance, this inverted organic photovoltaic cell uses another TiO2 layer as electron selective layer contacted to ITO coated glass su...

Xie, F. X.; Liang, C. J.; He, Z. Q.; Tao, Y. L.

2009-01-01

292

Hydrothermal growth of rutile TiO2 nanorod films on titanium substrates  

International Nuclear Information System (INIS)

Rutile TiO2 nanorod films have been successfully prepared on titanium substrate via a hydrothermal method using Tetra-n-butyl titanate as Ti source in the presence of concentrated hydrochloric acid. The effect of Ti substrate annealing treatment and adding of additional alkali metal chlorides in hydrothermal solution on the growth of TiO2 nanorod films has been studied using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and water contact angle measurement. The growth mechanism of the TiO2 nanorods on Ti substrate has also been discussed. It has shown that the initial rutile film transformed from anatase promotes the nucleation and epitaxial growth of rutile TiO2 nanorods. The superior wettabilities of the TiO2 nanorods resulted from treatments of vacuum and ultraviolet show great potential for applications in orthopaedic, dental implants, and possible photocatalysis.

2011-05-31

293

CoFe2O4-TiO2 and CoFe2O4-ZnO thin film nanostructures elaborated from colloidal chemistry and atomic layer deposition.  

Science.gov (United States)

CoFe(2)O(4)-TiO(2) and CoFe(2)O(4)-ZnO nanoparticles/film composites were prepared from directed assembly of colloidal CoFe(2)O(4) in a Langmuir-Blodgett monolayer and atomic layer deposition (ALD) of an oxide (TiO(2) or ZnO). The combination of these two methods permits the use of well-defined nanoparticles from colloidal chemistry, their assembly on a large scale, and the control over the interface between a ferrimagnetic material (CoFe(2)O(4)) and a semiconductor (TiO(2) or ZnO). Using this approach, architectures can be assembled with a precise control from the Angstrom scale (ALD) to the micrometer scale (Langmuir-Blodgett film). The resulting heterostructures present well-calibrated thicknesses. Electron microscopy and magnetic measurement studies give evidence that the size of the nanoparticles and their intrinsic magnetic properties are not altered by the various steps involved in the synthesis process. Therefore, the approach is suitable to obtain a layered composite with a quasi-monodisperse layer of ferrimagnetic nanoparticles embedded in an ultrathin film of semiconducting material. PMID:21067161

Clavel, Guylhaine; Marichy, Catherine; Willinger, Marc-Georg; Ravaine, Serge; Zitoun, David; Pinna, Nicola

2010-12-01

294

Structural characterization and properties of the TiO2 film on tinplate  

International Nuclear Information System (INIS)

A TiO2 film as chromate replacement was prepared on tinplate using sol-gel method, and appears golden. Sulfide-stain resistance of the TiO2-treated, chromate-treated and untreated tinplates was evaluated using a cysteine tarnish test. Corrosion behavior of these tinplates in contact with 3.5% NaCl solution and 0.1 M citric-citrate buffer solution was investigated using electrochemical impedance spectroscopy (EIS) measurement. The results show that the TiO2 film is more effective in improving sulfide-stain resistance and corrosion protection property of tinplate compared with the chromate-passivation film. Moreover, the cross hatch test reveals that the TiO2-treated tinplate provides excellent adhesion to the epoxyphenolic lacquer. The morphology, composition and thickness of the TiO2 film on tinplate were studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence spectrometry (XRF), respectively. According to the results, the TiO2 film is homogeneous and crack-free. The film mainly consists of TiO2, and the total titanium amount of the film is 0.0996 g/m2

2008-10-06

295

In-situ X-ray diffraction studies of time and thickness dependence of crystallization of amorphous TiO2 thin films and stress evolution  

International Nuclear Information System (INIS)

Remarkable properties of titanium dioxide films such as hydrophilicity or photocatalytic activity depend largely on their phase composition, microstructure and in particular on the crystallinity. By in-situ X-ray diffraction studies of isochronal and isothermal annealing of amorphous films with different thickness at different temperatures it was found that the crystallization process can be quite well described by the Johnson-Mehl-Avrami-Kolmogorov formula modified by the introduction of crystallization onset. This and other parameters of the formula strongly depend on the film thickness. For thickness below about 500 nm the crystallization is very slow. Simultaneously, the appearance and increase of tensile stresses with the annealing time were observed and these stresses were confirmed by detailed studies by both total pattern fitting and sin2? method on post-annealed samples. The stresses rapidly increase with decreasing thickness of the films. It seems that there is a strong correlation between the stresses and crystallization onset and/or crystallization rate. Tensile stresses that are generated during crystallization further inhibit crystallization and cause significant thickness dependence of the crystallization. The temperature and time dependence of microstructure of crystallized amorphous films differ significantly from those obtained for as-deposited nanocrystalline films or nanocrystalline powders. During annealing, quite large crystallites are formed quickly with the preferred orientation (001) that is suppressed with the proceeding time.

2010-12-30

296

Synthesis and characterization of TiO2 nanoparticle films coated with organic dyes  

International Nuclear Information System (INIS)

The synthesis and characterization of TiO2 nanoparticle coated with organic dyes, coumarin and methyl orange was reported. The films were deposited onto ITO-covered glass substrate by controlled hydrolysis technique assisted with spin coating technique. The films were characterized by scanning electron microscope (SEM), X-ray dispersive (XRD) technique and ultraviolet-visible (UV-Vis) spectrophotometer. The average grain size of the TiO2 films is about 76 nm. The uncoated TiO2 film is crystalline with anatase and rutile structure. The coated TiO2 films with dye are also crystalline since the diffraction peaks have been observed at three angles. The maximum absorption of the film coated with coumarine dye is at 480 nm.

2009-05-01

297

Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO2 Films  

International Nuclear Information System (INIS)

Amorphous TiO2 thin films were radio frequency sputtered onto silicon monoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at 250 degree C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.

2009-01-01

298

Photoelectrochemical activity of liquid phase deposited TiO2 film for degradation of benzotriazole  

International Nuclear Information System (INIS)

TiO2 film deposited on glassy carbon electrode surface was prepared via the liquid phase deposition (LPD). The deposited TiO2 film before and after calcination was characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Based on the high photoelectrochemical activity of calcined LPD TiO2 film, the photoelectrocatalytic degradation of benzotriazole (BTA) was investigated. Compared with the electrochemical oxidation process, direct photolysis or photocatalysis for treatment of BTA, a synergetic photoelectrocatalytic degradation effect was observed using the LPD TiO2 film-coated electrode. Various factors influencing the photoelectrocatalytic degradation of BTA such as film calcination, applied bias potential, pH value, supporting electrolyte concentration and initial concentration of BTA were investigated. The COD removal for BTA solution was analyzed to evaluate the mineralization of the PEC process. Based on the degradation experimental results, a possible photoelectrocatalytic degradation mechanism for BTA was proposed.

2010-03-15

299

Photocatalytic characteristics of TiO2 films deposited by magnetron sputtering on polycarbonate at room temperature  

International Nuclear Information System (INIS)

Anatase TiO2 thin films were successfully grown at room temperature on polycarbonate substrates, using RF magnetron sputtering under various conditions. The deposition parameters used to examine the photocatalytic activity of TiO2 films included RF power, sputtering pressure, argon/oxygen ratio (O2/(Ar + O2)) and deposition time. An orthogonal array and analysis of variance (ANOVA) were used to determine the performance of the deposition process. The effects of the deposition parameters on the structure, morphology and photocatalytic performance of TiO2 films were analyzed using scanning electron microscopy (SEM), X-ray diffraction, a contact angle meter and UV/vis/NIR spectroscopy. The RF power was found to be the factor that most affected the water droplet contact angle and the sputtering pressure was found to be the second ranking factor. The results indicate that the photocatalytic performance is improved by increasing RF power, but an increase in sputtering pressure has an adverse effect. Higher photocatalytic activity is achieved for TiO2 films using an RF power of 210 W, sputtering pressure of 0.93 Pa, argon/oxygen ratio of 30% and a deposition time of 2 h.

2012-07-01

300

Fabrication and characterization of Ag-implantation modificated TiO2 films followed with thermal annealing  

International Nuclear Information System (INIS)

TiO2 thin films fabricated by direct-current (DC) reactive magnetron sputtering were implanted with Ag ions at 30 kV to fluences of 1 × 1016, 3 × 1016 and 5 × 1016 ions/cm2, and subsequently annealed at 500 °C for 2 h under Ar ambient. Cross-sectional transmission electron microscopy and X-ray photoelectron spectroscopy studies showed that the implanted Ag ions were incorporated in TiO2 to form Ag2O after thermal annealing. The Ag-implanted TiO2 film with fluence of 3 × 1016 ions/cm2 after an annealing showed improved photocatalytic efficiency comparing to TiO2 film. When the implantation fluence increased to the 5 × 1016 ions/cm2, the sample showed poorer phtotcatalytic efficiency. These results indicate that there exists an optimum Ag ions implantation fluence. The photocatalytic behavior can be explained by the effect of Ag+ on the physicochemical properties in terms of electronic structures and film texture

2013-07-15

 
 
 
 
301

Preparation and characterization of polyvinyl alcohol films containing TiO2 nanoparticles  

International Nuclear Information System (INIS)

Polyvinyl alcohol films (PVA) doped with nanoparticles of TiO2 were prepared and characterized. These materials were obtained from a suspension of nanoparticles of TiO2 and PVA in 10% aqueous solution, and stabilized by ultrasound. The films of PVA-TiO2 (10, 100 and 1000 ppm of TiO2), of approximately 100?m of thickness, were prepared by pouring the mixture on glass plates and drying at room temperature by 48 h. These films were characterized by infrared spectroscopy (FT-IR) and UV-visible. No evidence of interaction between the chains of PVA and TiO2 was found. The dispersion of the TiO2 in the polymeric matrix was evaluated using the scanning electron microscopy (SEM). In spite of the treatment by ultrasound, the films show TiO2 agglomerates of different sizes. These films have better mechanical properties. It was observed an increase of the Young modulus as a function of the TiO2 concentration. Simultaneously the elongation of breakage diminishes. Nevertheless, significant changes in the tensile strength were not observed. (author)

2007-08-01

302

TiO2 anatase films obtained by direct liquid injection atomic layer deposition at low temperature  

Science.gov (United States)

TiO2 thin films were grown by direct liquid injection atomic layer deposition (DLI-ALD) with infrared rapid thermal heating using titanium tetraisopropoxide and water as precursors. This titanium tetraisopropoxide/water process exhibited a growth rate of 0.018 nm/cycle in a self-limited ALD growth mode at 280 °C. Scanning electron microscopy and atomic force microscopy analyses have shown a smooth surface with a low roughness. XPS results demonstrated that the films were pure and close to the TiO2 stoichiometric composition in depth. Raman spectroscopy revealed that the films were crystallized to the anatase structure in the as-deposited state at low temperature without necessity of high temperature annealing. Results obtained demonstrate that the liquid injection ALD is an efficient method of elaborating titanium oxide films using titanium tetraisopropoxide as precursor.

Avril, L.; Reymond-Laruinaz, S.; Decams, J. M.; Bruyère, S.; Potin, V.; de Lucas, M. C. Marco; Imhoff, L.

2014-01-01

303

One-pot synthesis of peacock-shaped TiO2 light scattering layer with TiO2 nanorods film for dye-sensitized solar cells  

Science.gov (United States)

A titanium dioxide (TiO2) film, showing distinctive functions and morphology, was prepared using the hydrothermal method by controlling the ratio of HCl:CH3COOH in acidic medium. A one-dimensional (1-D) TiO2 nanorod (NR) film was synthesized with a length of 2 ?m using a 1:2 ratio of HCl:CH3COOH, whereas a 1-D TiO2 NR film with peacock shaped TiO2 nanobundles as a light scattering layer (LSL) was acquired by employing a 2:1 ratio of HCl:CH3COOH. This LSL exhibited remarkable dual functions with respect to high light harvesting, which was attributable to the large surface area of the micrometer-sized TiO2 nanobundles, consisting of small-sized TiO2 NRs of 30-40 nm in diameter and a light scattering effect in the long wavelength region of 550-700 nm. Accordingly, the dual functions of the LSL resulted in a sharp increase in conversion efficiency (3.93%) that was about twice that (1.49%) of TiO2 NR film synthesized using a 1:2 ratio of HCl:CH3COOH. In particular, a considerably enhanced short-circuit photocurrent (Jsc) was mainly responsible for the resulting increase in overall efficiency with a moderate increase in fill factor and slightly reduced open-circuit voltage.

Kim, Hyun Sik; Kim, Young-Jea; Lee, Wonjoo; Kang, Soon Hyung

2013-05-01

304

Impact of Thickness of Columnar Crystal TiO2 Film on Photocatalytic Activity of FTO/TiO2 Coated Glass  

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Full Text Available Columnar crystal structured TiO2 thin films were prepared on the FTO (SnO2: F) low―emissivity coated glass substrates, obtaining double―layer structure FTO/TiO2 coated glass samples. The effect of TiO2 film thickness on the photocatalytic activity, the low―emissivity performance and light transmission properties of the FTO/TiO2 coated glass samples was investigated. The results showed that the photocatalytic activity of the samples increased firstly and then decrease with the increase of the film thickness. The best catalytic activity was observed for the sample coated with 300 nm TiO2 film. The low―emissivity properties of the samples declined as the TiO2 film thickness increased. The sample still have some low―emissivity performance when the TiO2 film thickness is 300 nm, while the light transmittance of the samples have little relations with the TiO2 films thickness. The visible light transmittances of the samples remain at about 72% with a smooth surface. The average surface roughness of the sample is about 1 nm. The FTO/TiO2 coated glass has photocatalytic self―cleaning properties with excellent low emissive performance and light transmittance property, thus guaranteeing good application prospects.

TENG Fan, LIU Yong, GE Yan-Kai, ZHANG Rui-Shuo, SONG Chen-Lu, HAN Gao-Rong

2012-06-01

305

SAXS Studies of TiO2 Nanoparticles in Polymer Electrolytes and in Nanostructured Films  

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Full Text Available Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO8ZnCl2/TiO2 themselves contained TiO2 nanograins. In this work, the influence of the TiO2 nanograins on the morphology and ionic conductivity of the nanocomposite was systematically studied by transmission small-angle X-ray scattering (SAXS simultaneously recorded with wide-angle X-ray diffraction (WAXD and differential scanning calorimetry (DSC at the synchrotron ELETTRA. Films containing nanosized grains of titanium dioxide (TiO2 are widely used in the research of optical and photovoltaic devices. The TiO2 films, prepared by chemical vapor deposition and e-beam epitaxy, were annealed in hydrogen atmospheres in the temperature range between 20 °C and 900 °C in order to study anatase-rutile phase transition at 740 °C. Also, grazing-incidence small angle X-ray scattering (GISAXS spectra for each TiO2 film were measured in reflection geometry at different grazing incident angles. Environmentally friendly galvanic cells, as well as solar cells of the second generation, are to be constructed with TiO2 film as working electrode, and nanocomposite polymer as electrolyte.

Sigrid Bernstorff

2010-11-01

306

Photoluminescence of TiO2 films co-doped with Tb3+/ Gd3+and energy transfer from TiO2/Gd3+ to Tb3+ ions  

International Nuclear Information System (INIS)

Nanometer TiO2 thin films doped with different concentration of Tb were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. XRD results show preferentially oriented (101) anatase films. TEM image indicates that the TiO2 films consist of TiO2 grains with diameter about 15 nm. Under room temperature, strong visible luminescence of Tb3+ ions due to intra-4f shell transitions are obtained and the PL intensity is found to have a well matching relation with the doping concentration of Tb3+ ions. Concentration quenching of PL occurs when Tb3+ concentration exceeds a certain value (9.2 mol%). Furthermore, the luminescence intensity is improved obviously after co-doping with Gd3+ ions because of the sensitization effects of Gd3+ ions to Tb3+ ions in TiO2 system. The energy transfer mechanism from TiO2 and Gd3+ ions to Tb3+ ions was proposed.

2011-09-01

307

Studies on preparation and photocatalytic activities of TiO2 films  

International Nuclear Information System (INIS)

TiO2 films were prepared using a sol-gel method by dipping-lifting manner on the surface of glass pipes. The prepared TiO2 films are very uniformity and firm. Photo-catalytic degradation of heptane was studied, and the results show that the photocatalytic activity of TiO2 films increases gradually with the decreasing of heating temperature, and the heptane can be mineralized completely. For the TiO2 films calcined at 300 degree C, with the increasing of coating cycles, photocatalytic activity of TiO2 films increases gradually, and the stability of films is good to be deposited for a long time and be used repeatedly. The photocatalytic degradations of acetone, benzene, toluene and 1, 2-dichloroethene ethane were also studied on TiO2 films. The results show that benzene and toluene are degraded slowly, while heptane acetone and 1, 2-dichloroethene ethane can be degraded quickly to produce chemical metrological ratio carbon dioxide

2003-11-01

308

Effect of deposition parameters on the photocatalytic activity and bioactivity of TiO2 thin films deposited by vacuum arc on Ti-6Al-4V substrates.  

Science.gov (United States)

This article evaluates the influence of the main parameters in a cathodic arc deposition process on the microstructure of titanium dioxide thin coatings and correlates these to the photocatalytic activity (PCA) and in vitro bioactivity of the coatings. Bioactivity of all as deposited coatings was confirmed by the growth of uniform layers of hydroxyapatite (HA) after 7 days in phosphate buffered saline at 37°C. Comparison of the HA growth after 24 h indicated enhanced HA formation on coatings with small titanium dioxide grains of rutile and anatase phase. The results from the PCA studies showed that coatings containing a mixed microstructure of both anatase and rutile phases, with small grain sizes in the range of 26-30 nm and with a coating thickness of about 250 nm, exhibited enhanced activity as compared with other microstructures and higher coating thickness. The results of this study should be valuable for the development of new bioactive implant coatings with photocatalytically induced on-demand antibacterial properties. PMID:22447517

Lilja, Mirjam; Welch, Ken; Astrand, Maria; Engqvist, Håkan; Strømme, Maria

2012-05-01

309

Femtosecond laser ablation of TiO2 films for two-dimensional photonic crystals  

Science.gov (United States)

Femtosecond laser ablation of TiO2 thin films was studied as a function of laser pulse energy and number of pulses. The ablated holes were characterized by atomic force microscopy and the optimum irradiation conditions were chosen for producing a periodic structure of triangular lattice of air holes in the TiO2 films. A photonic structure with period of 1.5 ?m was designed to show photonic band gap in the near-infrared, at the telecommunication wavelengths. The plane wave expansion method was used to compute the photonic band gap of the laser ablated structure. The impact of limited laser processing accuracy on the photonic band gap has been studied as variation of the radius of the holes. The structure was produced by tightly focused femtosecond laser beam in multi-pulses ablation regime, using a Ti:Sapphire CPA laser system with pulse duration of 200 fs and energy per pulse of tens of nanojoule for a focusing optics with numerical aperture NA=0.5. The optimum irradiation conditions were found as following: number of pulse N=15 and laser beam energy E=58 nJ. The resulting periodic structure has an estimated photonic band gap centered at 1.53 ?m with a bandwidth of about 42 nm.

Anghel, Iulia; Jipa, Florin; Andrei, Andreea; Simion, Sandel; Dabu, Razvan; Rizea, Adrian; Zamfirescu, Marian

2013-11-01

310

Micro-twins TiO2 nanorods grown on seeded ZnO film  

Science.gov (United States)

TiO2 anatase nanorods (NRs) epitaxially grew along the [001] direction at 600 °C on seeded c-axis oriented ZnO films which were deposited on a quartz glass substrate. The length of TiO2 NRs was about 450 nm. Micro-twins (MTs) were found in the TiO2 NRs with the (103) plane as the twin planes. The possible growth mechanisms of these TiO2 MTs have been studied using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The photo-degradation experiment showed that the TiO2 NRs have a high degradation efficiency of 32.9%. The effects of structural defects and MTs on the photocatalytic activity have been discussed.

Zhao, Lei; Xia, Maosheng; Liu, Yuhua; Zheng, Biju; Jiang, Qing; Lian, Jianshe

2012-04-01

311

Structural distortion effect in the cobalt ions implanted TiO2 films  

International Nuclear Information System (INIS)

TiO2 thin films were prepared by direct current magnetron sputtering on glass substrates, then were implanted by cobalt ions, and finally annealed at 400 and 500 deg. C for 50 min, respectively. They were identified as an anatase structure by X-ray diffraction (XRD). Scanning electron microscope (SEM) images showed that the grain sizes of the films grow with increasing annealing temperature. The energy dispersive X-ray (EDX) measurements indicated that the ratio of the cobalt atoms number and total atoms number of cobalt and titanium in the Co-TiO2 films was about 2.51%, and X-ray photoelectron spectroscopy (XPS) results revealed that the cobalt existed in the films as Co2+. The element distribution of cobalt along cross-section of the films was studied by EDX, as the results showed that the cobalt diffused deeply into the films after annealing. The high resolution transmission electron microscopy (HRTEM) images were used to affirm the anatase structure of the Co-TiO2 films, and edge dislocations were further found in the HRTEM images, which could be attributed to the effect of the implantation.

2009-09-15

312

Preparation of TiO2/SiO(x) double-layer films on glass beads and its application to NO and SO2 removal.  

Science.gov (United States)

Glass beads were coated with SiO(x) thin film as the first layer and with TiO2 thin film as the second layer by a rotating cylindrical PCVD reactor. The thicknesses of TiO2/SiO(x) double-layer films were measured by scanning electron microscopy. Glass beads coated with TiO2/SiO(x) double-layer films were packed inside the cylindrical reactor. NO and SO2 removal by dielectric barrier discharge-photocatalyst (DBD-P) hybrid process was tested for various conditions of process variables. The NO and SO2 removal efficiencies were improved by using a combination of dielectric barrier discharge and photodegradation by TiO2/SiO(x) double-layer films. The stronger the applied voltage is, the higher the pulse frequency is, or the longer the gas residence time is, the higher the NO and SO2 removal efficiencies become. In this study, we found that the glass beads coated with TiO2/SiO(x) double-layer films by a rotating cylindrical PCVD reactor could be used effectively to remove NO and SO2 by DBD-P hybrid process. PMID:23882796

Pham, Hung-Cuong; Kim, Kyo-Seon

2013-08-01

313

Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2  

International Nuclear Information System (INIS)

Electrochromic multilayer films consisting of polyoxometalate (POM) cluster K6[P2W18].14H2O (P2W18), TiO2 and polyallylamine hydrochloride (PAH) were fabricated on quartz, silicon wafer and ITO substrates by the layer-by-layer self-assembly method. The multilayer films were characterized by UV-vis spectrum, scanning electron microscopy (SEM), cyclic voltammetry (CV) and chronoamperometric (CA) and in situ spectral electrochemical measurements. The interesting feature is that the electrochromic films can increase stability due to the presence of TiO2. The multilayer films exhibit high optical contrast, suitable response time and low operation potential. TiO2 is employed to enhance stability of the electrochromic multilayer films based on POMs by the layer-by-layer method, which gives valuable information for exploring new stable electrochromic materials.

2009-07-15

314

Phase-controlled preparation of TiO2 films and micro(nano)spheres by low-temperature chemical bath deposition  

International Nuclear Information System (INIS)

Highlights: •Simultaneously preparation of TiO2 films and sphere-like precipitates by low-temperature chemical bath deposition. •The same building blocks observed in the films and precipitates. •Cluster-by-cluster attachment is succeeded by the ion-by-ion growth. •Phase-controlled growth of TiO2 by the effects of solvent or fluorine ion. -- Abstract: TiO2 films and micro(nano)spheres have been simultaneously prepared by means of low-temperature chemical bath deposition (CBD). The films and precipitates are found to be constructed of the same building blocks regardless of the bath conditions. Thin nanosheets of ca. 20 nm in thickness serve as the building blocks of rutile TiO2 grown in an acidic bath. They aggregate to form spheres to reduce the surface energy of the precipitates, while in the films they grow into discrete crystallites on the seeded substrate. Fine control over the crystalline phase of TiO2 is achieved by replacing some water with ethanol or the addition of NH4F. A gradual transition from rutile to anatase is observed as the ethanol and NH4F contents are increased. Moreover, the crystallite size of TiO2 is significantly reduced and there exists monodisperse nanoparticles and aggregate microspheres in the products modified with ethanol and NH4F, respectively. This size-dependent phase transition is consistent with previous theoretical and thermodynamic studies. The facile tune of the TiO2 phase by low-temperature CBD method may be useful to improve the performance of TiO2 for its various applications

2013-11-25

315

Robust superamphiphobic film from electrospun TiO2 nanostructures.  

Science.gov (United States)

Rice-shaped TiO2 nanostructures are fabricated by electrospinning for creating a robust superamphiphobic coating on glass substrates. The as-fabricated TiO2 nanostructures (sintered at 500 °C) are superhydrophilic in nature which upon silanization turn into superamphiphobic surface with surface contact angle (SCA) values achieved using water (surface tension, ? = 72.1 mN/m) and hexadecane (surface tension, ? = 27.5 mN/m) being 166° and 138.5°, respectively. The contact angle hysteresis for the droplet of water and hexadecane are measured to be 2 and 12°, respectively. Thus, we have successfully fabricated superior self-cleaning coatings that possess exceptional superamphiphobic property by employing a simple, cost-effective, and scalable technique called electrospinning. Furthermore, the coating showed good mechanical and thermal stability with strong adherence to glass surface, thus revealing the potential for real applications. PMID:23427896

Ganesh, V Anand; Dinachali, Saman Safari; Nair, A Sreekumaran; Ramakrishna, Seeram

2013-03-13

316

Ion-irradiation enhanced epitaxial growth of sol-gel TiO2 films  

International Nuclear Information System (INIS)

We report the epitaxial growth of sol-gel TiO2 films by using ion-irradiation enhanced synthesis. Our present study shows that the ion-beam process can provide highly crystalline TiO2 even at 350 C. Nuclear energy deposition at amorphous/crystalline interface plays a dominant role in the epitaxial growth of the films at the reduced temperature via a defect-migration mechanism. In addition, the ion irradiation allows for increasing the film density by balancing the crystallization rate and the escape rate of organic components. (orig.)

2011-04-01

317

The influence of metal interlayers on the structural and optical properties of nano-crystalline TiO2 films  

International Nuclear Information System (INIS)

TiO2-M-TiO2 (M = W, Co and Ag) multilayer films have been deposited on glass substrates using reactive magnetron sputtering, then annealed in air for 2 h at 500 °C. The structure, surface morphology and optical properties of the films have been studied using X-ray diffraction, Raman spectroscopy, atomic force microscopy and UV-vis spectroscopy. The TiO2-W-TiO2 and TiO2-Co-TiO2 films showed crystalline phases, whereas the TiO2-Ag-TiO2 films remained in the amorphous state. The crystallization temperature for the TiO2-M-TiO2 films decreased significantly compared with pure TiO2 film deposited on quartz. Detailed analysis of the Raman spectra suggested that the crystallization of TiO2-M-TiO2 films was associated with the large structural deformation imposed by the oxidation of intermediate metal layers. Moreover, the optical band gap of the films narrowed due to the appearance of impurity levels as the metal ions migrated into the TiO2 matrix. These results indicate that the insertion of intermediate metal layers provides a feasible access to improve the structural and optical properties of anatase TiO2 films, leading to promising applications in the field of photocatalysis.

2012-03-01

318

Influences on photovoltage performance by interfacial modification of FTO/mesoporous TiO2 using ZnO and TiO2 as the compact film  

International Nuclear Information System (INIS)

Highlights: ? ZnO has been introduced as the compact layer in dye-sensitized solar cells by a facile spin-coating method. ? The influences of ZnO and TiO2 compact films to photoelectron conversion process have been systematically investigated. ? The duel effect to photoelectron conversion process of ZnO compact film has been found. ? A new methodology of introducing an energy barrier at FTO/TiO2 interface rather than the surface of TiO2 electrode has been brought up. - Abstract: An effective ZnO compact film (ZCF) has been introduced at the interface of fluorine doped tin oxide (FTO) substrate and mesoporous TiO2 layer, and its effect on dye-sensitized solar cells (DSSCs) has been compared to that of conventional TiO2 compact film (TCF). The ZCF and TCF prepared by spin-coating method on FTO are characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and UV-vis spectrophotometer. The existence of TiO2 can suppress the recombination occurring at the interface of FTO/electrolyte, resulting in a higher Jsc and Voc than bare FTO. The ZCF creates an energy barrier between FTO substrate and mesoporous TiO2 layer, which not only reduces the electron back transfer from FTO to I3- in the electrolyte, but also leads to the accumulation of photogenerated electrons, and increases the electron density in the conduction band of TiO2. The device based on FTO/ZCF substrate remarkably improves Voc and FF, finally increases energy conversion efficiency by 13.1% compared to the device based on bare FTO and 4.7% compared to the counterpart based on FTO/TCF.

2011-09-15

319

Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV to develop nanocomposite films for photovoltaic applications.  

Science.gov (United States)

The present study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different morphologies using oleic acid (OA) and oleyl amine (OM) as capping agents. Different shapes of NPs, such as nanospheres, nanorods, and nanorhombics, were achieved. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. Obtained results showed promising properties for photovoltaic devices, especially solar radiation absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs. PMID:22755128

Vu, Thi Thuy Duong; Mighri, Frej; Do, Trong-On; Ajji, Abdellah

2012-03-01

320

Preparation of Ordered Porous TiO2 Film from Honeycomb Structured TBT/PMMA Hybrid Film  

Directory of Open Access Journals (Sweden)

Full Text Available TBT/PMMA organic-inorganic hybrid honeycomb patterned film was prepared by Breath Figures method, then it was suffered vapor phase hydrothermal treatment and transformed into ordered porous TiO2 film via pyrolysis process. The hole structure was investigated during the vapor phase hydrothermal treatment and pyrolysis process. The results show that, during the vapor phase hydrothermal treatment, TBT hydrolyzes to titanium hydrogen oxide hydrates, forming the strongerTiOnetworks, which therefore prevents the PMMA from liquefied in the pyrolysis process, as a result the ordered porous TiO2 film is obtained. Compared with non-hydrothermal treated TiO2 film, the resulted ordered porous TiO2 film enhances the photoelectrochemical response and its photocurrent density is increased by 3 times under UV light irradiation.

SHEN Yan-Ming, LIU Dan, WU Jing, LIU Ya-Qi, JI Sheng-Fei, LI Tian-Shu

2010-07-01

 
 
 
 
321

Photocatalytic properties of TiO2 films prepared by O2 cluster ion beam assisted deposition method  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) films were prepared on Si(1 0 0) substrate by oxygen (O2) cluster ion beam assisted deposition method. The TiO2 films prepared at a substrate temperature of 200 deg. C or less were amorphous, whereas those at a substrate temperature of 300 deg. C contained both rutile and anatase. The refractive indexes of the TiO2 films increased with increasing substrate temperature. The surface state of the TiO2 film was smooth at an atomic level. The TiO2 films prepared at a substrate temperature of 300 deg. C showed high photocatalytic decomposition of methylene blue by ultraviolet (UV) irradiation, similar to those of TiO2(1 0 0) bulk state in a rutile structure. The contact angle of the TiO2 film with an initial value of 75 deg. decreased to 10 deg. by UV irradiation for 30 min, although that for TiO2(1 0 0) bulk state in rutile structure remained at the initial value even after the UV irradiation. It is considered that anatase in the TiO2 films was contributed to both photocatalytic decomposition and photocatalytic hydrophilicity of the films

2005-05-01

322

Sol-gel TiO2 films as NO2 gas sensors  

Science.gov (United States)

TiO2 films were prepared by a sol-gel technique with commercial TiO2 powder as a source material (P25 Degussa AG). After a special treatment, printing paste was prepared. The TiO2 layers were formed by means of drop-coating on Si-control wafers and on the Au-electrodes of quartz resonators. The surface morphology of the films was examined by scanning electron microscopy (SEM). Their structure was studied by Raman spectroscopy and the surface composition was determined by X-ray photoelectron spectroscopy (XPS). The layers had a grain-like surface morphology and consisted mainly of anatase TiO2 phase. The sensitivity of the TiO2 films to NO2 was assessed by the quartz crystal microbalance (QCM) technique. To this end, the films were deposited on both sides of a 16-MHz QCM. The sensing characteristic of the TiO2-QCM structure was investigated by measuring the resonant frequency shift (?F) of the QCM due to the mass loading caused by NO2 adsorption. The Sauerbrey equation was applied to establish the correlation between the QCM frequency changes measured after exposure to different NO2 concentrations and the mass-loading of the QCM. The experiments were carried out in a dynamic mode on a special laboratory setup with complete control of the process parameters. The TiO2 films were tested in the NO2 concentration interval from 10 ppm to 5000 ppm. It was found that a TiO2 loading of the QCM by 5.76 kHz corresponded to a system sensitive to NO2 concentrations above 250 ppm. On the basis of the frequency-time characteristics (FTCs) measured, AF at different NO2 concentrations was defined, the adsorption/desorption cycles were studied and the response and recovery times were estimated. The results obtained show that the process is reversible in the NO2 interval investigated. The results further suggested that TiO2 films prepared by a sol-gel method on a QCM can be used as a sensor element for NO2 detection.

Georgieva, V.; Gadjanova, V.; Grechnikov, A.; Donkov, N.; Sendova-Vassileva, M.; Stefanov, P.; Kirilov, R.

2014-05-01

323

Influence of titanium precursor on the photocatalytic properties of TiO2 sprayed films under visible light  

Science.gov (United States)

Thin nano-sized TiO2 films were deposited on aluminum foil substrates by the spray pyrolysis method, using Ti(i-OPr)4 (TIP) and TiCl4 (TC) as precursors. The films were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). According to the XRD patterns the as-deposited films appear to be amorphous. The thermal treatment at 400°C leads to the formation of anatase nano-crystallites. The XPS analyses showed that the Ti2p broad photoelectron peak of as-deposited TC films indicated a mixture of Ti3+ and Ti4+ oxidation states. After treatment at 400°C the Ti2p peak displays only Ti4+ oxidation state for both TIP and TC films. The number of hydroxyl groups on the surface is decreased after the thermal treatment. The photocatalytic activity of the films was studied towards degradation of azo dye Reactive Black 5 (RB5) as model wastewater pollutant under visible light illumination. It was found out that the films obtained from TC were more active than those obtained from TIP films. The thermally treated samples are better photocatalysts than those non-treated, because they posses anatase crystalline phase and stoichiometric TiO2. The TOC measurements showed minimal concentration of total organic carbon in the dye solution after 180 min of visible light irradiation.

Blaskov, V.; Shipochka, M.; Stambolova, I.; Vassilev, S.; Eliyas, A.; Stefanov, P.; Loukanov, A.

2012-12-01

324

Incorporation of N in TiO2 films grown by DC-reactive magnetron sputtering  

International Nuclear Information System (INIS)

Photocatalytic properties of TiO2 are expected to play an important role on emerging technologies based on OH radicals to destroy harmful nonbiodegradable organic and inorganic contaminants in water. The drawback is the wide band gap of TiO2 (3.2 eV) limiting its use to the UV part of electromagnetic spectrum under sunlight. Therefore, modifications of TiO2 are needed to tune the gap in order to allow an efficient use of the entire solar spectrum. One possibility is N-doping of TiO2 to make the photocatalytic activity possible under visible light and more suitable for water treatment. In our study nitrogen-doped TiO2 (TiO2?xNx) films were deposited by DC-reactive magnetron sputtering using a dual-magnetron co-deposition apparatus on unheated glass and silicon substrates using a pure titanium target. The depth profile of nitrogen was measured with heavy ion elastic recoil detection analysis combined with Rutherford backscattering spectrometry (RBS) and correlated with the optical and structural properties obtained by UV–VIS spectroscopy and X-ray diffraction (XRD).

2012-02-15

325

Origin of visible-light sensitivity in N-doped TiO2 films  

International Nuclear Information System (INIS)

We report on visible-light sensitivity in N-doped TiO2 (TiO2:N) films that were deposited on n+-GaN/Al2O3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N2 gas. The N-doping concentration was ?8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO2:N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ?1.18 and ?2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO2:N

2007-10-15

326

Visible light active TiO2 films prepared by electron beam deposition of noble metals  

International Nuclear Information System (INIS)

TiO2 films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO2 films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO2 is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO2 films by this method is affected by the concentration of impregnating solution.

2010-03-15

327

Visible light active TiO 2 films prepared by electron beam deposition of noble metals  

Science.gov (United States)

TiO 2 films prepared by sol-gel method were modified by electron beam deposition of noble metals (Pt, Pd, and Ag). Effects of noble metals on the chemical and surface characteristics of the films were studied using XPS, TEM and UV-Vis spectroscopy techniques. Photocatalytic activity of modified TiO 2 films was evaluated by studying the degradation of methyl orange dye solution under visible light UV irradiation. The result of TEM reveals that most of the surface area of TiO 2 is covered by tiny particles of noble metals with diameter less than 1 nm. Broad red shift of UV-Visible absorption band of modified photocatalysts was observed. The catalytic degradation of methyl orange in aqueous solutions under visible light illumination demonstrates a significant enhancement of photocatalytic activity of these films compared with the un-loaded films. The photocatalytic efficiency of modified TiO 2 films by this method is affected by the concentration of impregnating solution.

Hou, Xing-Gang; Ma, Jun; Liu, An-Dong; Li, De-Jun; Huang, Mei-Dong; Deng, Xiang-Yun

2010-03-01

328

Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering  

International Nuclear Information System (INIS)

Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O2 gas supply is periodically interrupted rather than by a decrease of the partial O2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 × 102 cm-1 to more than 4 × 103 cm-1 as a result of the gas flow discontinuity. A red-shift of ?0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40 nm. Moreover, the interruptions of the O2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films.

2012-06-01

329

TiO2 Coating for SnO2:F Films Produced by Filtered Cathodic Arc Evaporation for Improved Resistance to H+ Radical Exposure  

Science.gov (United States)

Titanium dioxide thin films were deposited by filtered cathodic arc evaporation (FCAE) from a Ti target in an oxygen atmosphere onto (a) fluorine-doped tin oxide substrates SnO2:F (FTO) and (b) glass microscope slides. The growth rate calculated from film thickness profilometry measurements was found to be approximately 0.8 nm/s. The films were highly transparent to visible light. x-Ray photoemission spectroscopy analysis of the Ti 2p electron binding- energy shift confirmed the presence of a TiO2 stoichiometric compound. The results for the root-mean-square (RMS) surface roughness of the films deposited onto FTO substrates evaluated by atomic force microscopy suggested nanostructured film surfaces. When exposed to hydrogen plasma, TiO2 films revealed insignificant changes in the optical spectra. The initial sheet resistance of the SnO2:F layer was 14 ?/sq. The deposition of the top TiO2 layer (45 nm thick) over the FTO electrode resulted in an increase of the sheet resistance of 2 ?/sq. In addition, the sheet resistance of the double-layer FTO/TiO2 transparent conductive oxide (TCO) electrode increased by 1 ?/sq as a result of H+ plasma exposure. Regardless of the TiO2 film's low conductivity, a thin protective layer could be coated onto FTO films (presumably 15 nm thick) due to their high transparency, offering high resistance to aggressive H+ plasma conditions. In this paper we show that ˜50-nm-thick TiO2 coating on FTO films provides sufficient protection against deterioration of transparency and conductivity due to hydrogen radical exposure.

Ristova, M. M.; Gligorova, A.; Nasov, I.; Gracin, D.; Milun, M.; Kostadinova-Boskova, H.; Popeski-Dimovski, R.

2012-11-01

330

Intense Photocurrent from Mo-Doped TiO2 Film with Depletion Layer Array.  

Science.gov (United States)

A novel bilayer structure of TiO2 film was found capable of yielding fairly strong photocurrent under visible light. The base layer was lightly doped with Mo and then etched by reactive ion beam, and was finally covered by an undoped TiO2 surface layer. Because of Fermi level drop at the interface of the trenches, such a deposition-etching-redeposition process implanted an array of depletion layer into TiO2 film successfully. Microstructures, crystallite parameters, and the absorption property were investigated with scanning electron microscope, atomic force microscopy, X-ray diffraction, and ultraviolet-visible spectroscopy in order. Photocurrent density was collected on an electrochemical workstation under visible light. The results indicate that carrier collection probability near depletion layer was enhanced significantly owing to high parallel diffusivity. Under visible light, current density demonstrates a marked increase as etching depth grows. At an etching depth around 660 nm, photocurrent density achieved is 56 times larger than TiO2 film. Depletion layer at vertical trench edges may have a much bigger universal value than anticipated for various doping cases of wide-bandgap films. PMID:24914805

Luo, Sheng-Yun; Yan, Bing-Xi; Shen, Jie

2014-06-25

331

Composite TiO2 film with quantum dots fabricated through a sol-gel process.  

Science.gov (United States)

A novel strategy has been developed to fabricate composite TiO2 films with CdTe quantum dots (QDs). Aqueous CdTe QDs with green-, yellow-, and red-emitting were prepared using thioglycolic acid as a capping agent. The QDs revealed high photoluminescence (PL) efficiencies under optimal preparation conditions. TiO2 sol was obtained by the controlling hydrolysis of tetrabutyl titanate in ethanol with poly(vinyl pyrrolidone). Diethanolamine was added to prevent the QDs from PL quenching generated by surface defects. After embedding the QDs in composite TiO2 film, the PL intensity of the QDs decreased because of the excitation and recombination between the QDs and TiO2. The PL peak wavelength of the QDs in films revealed a slight blue shift compared with their initial ones. The blue shift degree of the PL peaks depended on the properties of the QDs. Red-emitting CdTe QDs revealed a small blue shift of 1 nm while green-emitting ones revealed a blue shift of 7 nm. This indicated red-emitting QDs with high stability against incorporation. Facile preparation and excellent properties including high PL brightness, multicolor emission, and high stability make these films important applications in various fields. PMID:23763183

Ge, Lei; Liu, Ning; Yang, Ping; Cheng, Xin

2013-04-01

332

TiO2/CdSe core-shell nanofiber film for photoelectrochemical hydrogen generation  

Science.gov (United States)

We report on a novel core-shell TiO2/CdSe nanofiber photoanode for photoelectrochemical hydrogen generation. The core-shell nanofiber films, with a hierarchical network structure, are prepared on fluorine-doped tin oxide coated substrates via electrospinning pyrolysis and chemical bath deposition. The hierarchical network structure shows significantly improved photoelectrochemical properties due, we believe, to possessing more active sites for the oxidation reaction and a larger TiO2/CdSe interface area for photogenerated charges' separation. The synthesis details are discussed to provide a generic route for preparing other similar photoanodes with hierarchical network structures.

Liu, Ya; Zhao, Liang; Li, Mingtao; Guo, Liejin

2014-06-01

333

Variations in the structural, optical and electrochemical properties of CeO2-TiO2 films as a function of TiO2 content  

International Nuclear Information System (INIS)

Alcohol based sols of cerium chloride (CeCl3.7H2O) and titanium propoxide (Ti(OPr)4) in ethanol mixed in different mole ratios have yielded mixed oxide films on densification at 500 deg. C. The reversibility of the intercalation/deintercalation reactions has shown electrochemical stability of the films. Addition of TiO2 in an equivalent mole ratio manifests in producing highly transparent films with appreciable ion storage capacity. The electrochemical studies have revealed the significant role of TiO2 in controlling the ion storage capacity of the films, as it tends to induce the disorder. In addition, the films prepared from an aged sol are observed to exhibit a much higher ion storage capacity than the films deposited using the as-prepared sol. The X-ray photoelectron spectroscopic studies have provided information on the variation of Ce4+/Ce3+ ratio as a function of increased TiO2 content in the films. This study has led to a better understanding of the increased ion storage capacity with the increased TiO2 proportion. The transmission electron microscopic study has demonstrated the presence of CeO2 nanograins even in films, which are amorphous to X-rays. Elucidation of the structural, optical and electrochemical features of the films has yielded information on aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties that can find application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. Also, the fastest coloration-bleaching kinetics for the primary electrochromic electrode (WO3) working in combination with Ce/Ti (1:1) electrode stimulates the use of latter in electrochromic windows (ECWs)

2006-05-15

334

Variations in the structural, optical and electrochemical properties of CeO 2-TiO 2 films as a function of TiO 2 content  

Science.gov (United States)

Alcohol based sols of cerium chloride (CeCl 3·7H 2O) and titanium propoxide (Ti(OPr) 4) in ethanol mixed in different mole ratios have yielded mixed oxide films on densification at 500 °C. The reversibility of the intercalation/deintercalation reactions has shown electrochemical stability of the films. Addition of TiO 2 in an equivalent mole ratio manifests in producing highly transparent films with appreciable ion storage capacity. The electrochemical studies have revealed the significant role of TiO 2 in controlling the ion storage capacity of the films, as it tends to induce the disorder. In addition, the films prepared from an aged sol are observed to exhibit a much higher ion storage capacity than the films deposited using the as-prepared sol. The X-ray photoelectron spectroscopic studies have provided information on the variation of Ce 4+/Ce 3+ ratio as a function of increased TiO 2 content in the films. This study has led to a better understanding of the increased ion storage capacity with the increased TiO 2 proportion. The transmission electron microscopic study has demonstrated the presence of CeO 2 nanograins even in films, which are amorphous to X-rays. Elucidation of the structural, optical and electrochemical features of the films has yielded information on aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties that can find application as counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. Also, the fastest coloration-bleaching kinetics for the primary electrochromic electrode (WO 3) working in combination with Ce/Ti (1:1) electrode stimulates the use of latter in electrochromic windows (ECWs).

Verma, Amita; Joshi, Amish G.; Bakhshi, A. K.; Shivaprasad, S. M.; Agnihotry, S. A.

2006-05-01

335

Transparent and conducting TiO2:Nb films made by sputter deposition : Application to spectrally selective solar reflectors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transparent and conducting thin films of TiO2:Nb were prepared on glass and aluminum substrates by dual-target reactive DC magnetron sputtering in an Ar+O-2 plasma. The Nb content lay between 0 and 4.9 at% as determined by ion beam analyses. X-ray diffraction showed that vacuum annealing at 450 degrees C led to crystallinity and prevalence of the anatase phase. The influence of Nb doping was studied with regard to structural, optical, and electrical data. Optical constants were determined fro...

Maghanga, Christopher M.; Jensen, Jens; Niklasson, Gunnar A.; Granqvist, Claes-go?ran; Mwamburi, M.

2010-01-01

336

Cascade structure of TiO2/ZnO/CdS film for quantum dot sensitized solar cells  

International Nuclear Information System (INIS)

Highlights: ? Solar cells based on a cascade structure of TiO2/ZnO/CdS photoanode are fabricated. ? ZnO is one-step deposited on TiO2 layer by ultrasonic spray pyrolysis technique. ? As-prepared cell achieves a power conversion efficiency of 1.56%. - Abstract: Quantum dot sensitized solar cells based on cascade structure of TiO2/ZnO/CdS electrode and polysulfide electrolyte were fabricated. The ZnO layer was deposited on screen-printed TiO2 layer by ultrasonic spray pyrolysis method. The structure, morphology and impedance of TiO2/ZnO film photoanode and the photovoltaic performance of TiO2/ZnO/CdS cell were investigated. It is found that the short circuit current density and conversion efficiency are significantly improved by the introduction of ZnO layer into TiO2/CdS film. A power conversion efficiency of about 1.56% has been obtained for TiO2/ZnO/CdS cell, which is about 57% higher than that for TiO2/CdS cell (0.99%). The formation of an inherent energy barrier between TiO2 and CdS films and the passivation of surface traps on the TiO2 film caused by the introduction of ZnO layer, which reduces the charge recombination and favors the electron transport, should be mainly responsible for the performance enhancement of TiO2/ZnO/CdS cell.

2011-07-21

337

Photo-fixation of SO2 in nanocrystalline TiO2 films prepared by reactive DC magnetron sputtering  

International Nuclear Information System (INIS)

We report on photo-fixation of SO2 onto nanostructured TiO2 thin films prepared by reactive DC magnetron sputtering. The films were exposed to 50 ppm SO2 gas mixed in synthetic air and illuminated with UV light at 298 and 473 K. The evolution of the adsorbed SOx species was monitored by in situ Fourier transform infrared specular reflection spectroscopy. Significant photo-fixation occurred only in the presence of UV illumination. The SO2 uptake was dramatically enhanced at elevated temperatures and then produced strongly bonded surface-coordinated SOx complexes. The total SOx uptake is consistent with Langmuir adsorption kinetics. The sulfur doping at saturation was estimated from X-ray photoelectron spectroscopy to be ? 2.2 at.% at 473 K. These films were pale yellowish and had an optical absorption coefficient being ? 3 times higher than in undoped film. The S-doped films exhibit interesting oleophobic properties, exemplified by the poor adherence of stearic acid. Our results suggest a new method for sulfur doping of TiO2 to achieve combined anti-grease and photocatalytic properties.

2009-12-15

338

Photocatalytic activity of erbium-doped TiO2 nanoparticles immobilized in macro-porous silica films  

International Nuclear Information System (INIS)

Highlights: ? Erbium-doped TiO2 nanoparticles were immobilized on macro-porous silica films. ? The films were obtained by a phase separation process. ? The samples exhibited photo-catalytic activity under visible light. ? The sensitization of TiO2 was attributed to a red shift in the TiO2 band-gap. -- Abstract: A macro-porous silica film served as mechanical support to immobilize TiO2 nanoparticles, which were doped with erbium. The films and the nanoparticles were prepared by sol–gel route. The nanoparticles exhibited photocatalytic activity under visible light. We obtained a degradation rate of methylene blue that followed first order kinetics. The sensitization of the nanoparticles to visible light was attributed to a red shift in the band-gap of the TiO2 due to the addition of erbium ions.

2012-02-01

339

Nanostructured Fe2O3/TiO2 thick films prepared by screen printing  

Directory of Open Access Journals (Sweden)

Full Text Available Nanostructured single layered (pure TiO2, pure ?-Fe2O3 and mixed Fe2O3/TiO2 with two different oxide ratios, 2 : 3 and 3 : 2 and double layered (TiO2 layer over a Fe2O3 layer thick films have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100 °C and sintered at 650 °C/60 minutes. Structural, morphological and optical studies have been carried out using XRD, SEM analyses and UV/Vis spectroscopy. The prepared pure and mixed Fe2O3/TiO2 thick films had a homogenous nanostructure without secondary phases. Indirect band gaps were determined from the measured transmission spectra and the obtained values are in the range of literature data.

Obrad S. Aleksic

2013-09-01

340

Quantum confinement in amorphous TiO2 films studied via atomic layer deposition  

International Nuclear Information System (INIS)

Despite the significant recent increase in quantum-based optoelectronics device research, few deposition techniques can reliably create the required functional nanoscale systems. Atomic layer deposition (ALD) was used here to study the quantum effects attainable through the use of this aangstroem-level controlled growth process. Size-dependent quantum confinement has been demonstrated using TiO2 layers of nanoscale thickness applied to the surfaces of silicon wafers. TiO2 films were deposited at 100 deg. C using TiCl4 and H2O2 in a viscous flow ALD reactor, at a rate of 0.61 A/cycle. The low-temperature process was utilized to guarantee the amorphous deposition of TiO2 layers and post-deposition thermal annealing was employed to promote crystallite-size modification. Hydrogen peroxide significantly reduced the residual chlorine that remained from a typical TiCl4-H2O ALD process at this temperature, down to 1.6%. Spectroscopic ellipsometry was used to quantify the optical properties both below and above the bandgap energy. A central composite design was employed to map the surface response of the film thickness-dependent bandgap shift for the as-deposited case and up to a thermal annealing temperature of 550 deg. C. The Brus model was used to develop a correlation between the amorphous TiO2 film thickness and the quantum length to promote equivalent bandgap shifts.

2008-11-05

 
 
 
 
341

High-rate low-temperature dc pulsed magnetron sputtering of photocatalytic TiO2films: the effect of repetition frequency  

Directory of Open Access Journals (Sweden)

Full Text Available AbstractThe article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2thin films using dc dual magnetron (DM sputtering in Ar + O2mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5 targets of 50 mm in diameter. The substrate surface temperature Tsurfmeasured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency frwas investigated in detail. It was found that the increase of frfrom 100 to 350 kHz leads to (a an improvement of the efficiency of the deposition process that results in a significant increase of the deposition rate aDof sputtered TiO2films and (b a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities. It was demonstrated that several hundreds nm thick hydrophilic TiO2films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.

Strýhal Z

2007-01-01

342

Synthesis of Bi2O3-TiO2 composite film with high-photocatalytic activity under sunlight irradiation  

International Nuclear Information System (INIS)

Bi2O3-TiO2 composite films were synthesized by a sol-gel method under mild condition (i.e. low temperature and ambient pressure). The as-prepared films were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, infrared spectra and fluorescence spectra. The results showed that Bi2O3-TiO2 composite films were composed of anatase titania and Bi2O3. TiO2 particles were deposited on the surface of Bi2O3 to form uniform film. Incorporating Bi2O3 with TiO2 leads to increased surface OH group density. All Bi2O3-TiO2 composite films exhibited higher photocatalytic activity compared with pure TiO2 under solar irradiation, while the film with Bi/Ti atomic ratio of 1.25% showed the highest photocatalytic activity. Furthermore, the as-prepared films can be reused with little photocatalytic activity decreasing. Without any further treatment besides rinsing, the photocatalytic activity of Bi2O3-TiO2 (1.25%) films was still higher than 77% after six-cycle utilization.

2008-12-30

343

Spectroscopic evidence of the formation of (V,Ti)O2 solid solution in VO2 thinner films grown on TiO2(001) substrates  

International Nuclear Information System (INIS)

We have prepared VO2 thin films epitaxially grown on TiO2(001) substrates with thickness systematically varied from 2.5 to 13 nm using a pulsed laser deposition method, and studied the transport property and electronic states of the films by means of resistivity and in situ synchrotron photoemission spectroscopy (SRPES). In resistivity measurements, the 13-nm-thick film exhibits a metal-insulator transition at around 290 K on cooling with change of three orders of magnitudes in resistivity. As the film thickness decreases, the metal-insulator transition broadens and the transition temperature increases. Below 4 nm, the films do not show the transition and become insulators. In situ SRPES measurements of near the Fermi level valence band find that the electronic state of the 2.5-nm-thick film is different than that of the temperature-induced insulator phase of VO2 itself although these two states are insulating. Ti 2p core-level photoemission measurements reveal that Ti ions exist near the interface between the films and TiO2 substrates, with a chemical state similar to that in (V,Ti)O2 solid solution. These results indicate that insulating (V,Ti)O2 solid solution is formed in the thinner films. We propose a simple growth model of a VO2 thin film on a TiO2(001) substrate. Near the interface, insulating (V,Ti)O2 solid solution is formed due to the diffusion of Ti ions from the TiO2 substrate into the VO2 film. The concentration of Ti in (V,Ti)O2 is relatively high near the interface and decreases toward the surface of the film. Beyond a certain film thickness (about 7 nm in the case of the present 13-nm-thick film), the VO2 thin film without any Ti ions starts to grow. Our work suggests that developing a technique for preparing the sharp interface between the VO2 thin films and TiO2 substrates is a key issue to study the physical property of an ultrathin film of ''pure'' VO2, especially to examine the presence of the novel electronic state called a semi-Dirac point phase predicted by calculations.

2011-02-15

344

Simple way to make Anatase TiO2 films on FTO glass for promising solar cells  

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TiO2 is a wide bandgap semiconductor material used as the photo anode in dye sensitized solar cells (DSSC). The fabrication of TiO2 on conductive glass substrates plays an important role in the solar cell efficiency, since the thickness of the TiO2 coating affects the transmission, photoconductive properties and the efficiency of solar cells. The uncorrected transmission in our fabricated films is as high as 80%, and the bandgap obtained is similar to that of bulk anatase TiO2, co...

Raghavender, A. T.; Samantilleke, A. P.; Sa?, Pedro; Almeida, B. G.; Vasilevskiy, Mikhail; Nguyen Hoa Hong

2011-01-01

345

Highly flexible self-standing film electrode composed of mesoporous rutile TiO2/C nanofibers for lithium-ion batteries  

International Nuclear Information System (INIS)

There is increasing interest in flexible, safe, high-power thin-film lithium-ion batteries which can be applied to various modern devices. Although TiO2 in rutile phase is highly attractive as an anode material of lithium-ion batteries for its high thermal stability and theoretical capacity of 336 mA h g?1 and low price, its inflexibility and sluggish lithium intercalation kinetics of bulk phase strongly limit its practical application for particular in thin-film electrode. Here we show a simple way to prepare highly flexible self-standing thin-film electrodes composed of mesoporous rutile TiO2/C nanofibers with low carbon content (2 in as-fabricated nanofibers. Big size (10 cm × 4 cm), flexible thin film is obtained after heat treatment under 10%H2–Ar at 900 °C for 3 h. After optimization, the diameter of fibers can reach as small as ?110 nm, and the as-prepared rutile TiO2 films show high initial electrochemical activity with the first discharge capacity as high as 388 mA h g?1. What is more, very stable reversible capacities of ?122, 92, and 70 mA h g?1 are achieved respectively at 1, 5 and 10 C rates with negligible decay rate within 100 cycling times.

2012-12-15

346

Plasmonic Ag deposited TiO2 nano-sheet film for enhanced photocatalytic hydrogen production by water splitting  

Science.gov (United States)

TiO2 nano-sheet film (TiO2 NSF) was prepared by a hydrothermal method. Ag nanoparticles (NPs) were then deposited on the surface of TiO2 NSF (Ag/TiO2 NSF) under microwave-assisted chemical reduction. The prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible (UV–vis) absorption spectroscopy, x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and Raman scattering spectroscopy. The results revealed that the Ag NPs were well dispersed on the anatase/rutile mixed-phase TiO2 nano-sheet surface with a metallic state. The visible light absorption and Raman scattering of TiO2 were enhanced by Ag NPs based on its surface plasmon resonance effect. Besides, Ag NPs could also effectively restrain the recombination of photogenerated electrons and holes. Photocatalytic water splitting was conducted on the films to obtain hydrogen, and the experimental results indicated that plasmonic Ag NPs could greatly enhance the photocatalytic activity of TiO2 due to the synergistic effect between electron transfer and surface plasmon resonance enhanced absorption. The hydrogen yield obtained from the optimal sample reached 8.1 ?mol cm?2 and the corresponding energy efficiency was about 0.47%, which was 8.5 times higher than that of pure TiO2 film. Additionally, the formation mechanism of TiO2 nano-sheet film is preliminarily discussed.

Liu, Enzhou; Kang, Limin; Yang, Yuhao; Sun, Tao; Hu, Xiaoyun; Zhu, Changjun; Liu, Hanchen; Wang, Qiuping; Li, Xinghua; Fan, Jun

2014-04-01

347

Photoemission study of TiO2/VO2 interfaces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite...

Maekawa, K.; Takizawa, M.; Wadati, H.; Yoshida, T.; Fujimori, A.; Kumigashira, H.; Oshima, M.; Muraoka, Y.; Nagao, Y.; Hiroi, Z.

2006-01-01

348

Efficient carbon-doped nanostructured TiO2 (anatase) film for photoelectrochemical solar cells  

International Nuclear Information System (INIS)

In this paper, we have demonstrated that carbon-doped nanostructured TiO2 (CD ns-TiO2) films could be prepared simply and cheaply with oxalic acid and tetrabutylammonium bromide (Bu4N.Br) as the carbon sources. The surface morphology of the films was a multiple-porous network structure.The average size of nanoparticle was about 40 nm. Carbon doped into substitutional sites of TiO2 has also proven to be indispensable for band-gap narrowing and photovoltaic effect. Carbon doping lowered the band gap of n-TiO2 to 1.98, 1.64, and 1.26 eV. The CD ns-TiO2 film was first used as photoanode for solar cells, exhibiting high photocurrent densities (l.34 mA/cm2) and yielding an overall conversion efficiency (?) of 4.42 %

2008-02-01

349

Nano-structure TiO2 film coating on 316L stainless steel via sol-gel technique for blood compatibility improvement  

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Full Text Available   Objective(s: Titanium oxides are known to be appropriate hemocompatible materials which are suggested as coatings for blood-contacting devices. Little is known about the influence of nanometric crystal structure, layer thickness, and semiconducting characteristics of TiO2 on blood hemostasis.   Materials and Methods: Having used sol-gel dip coating method in this study, TiO2 thin films were deposited on nano-scale electro-polished stainless steel 316L with 1 to 5 nano-sized layers. Surface morphology and structure of the film were studied with X-ray diffraction and atomic force microscopy. Blood compatibility was also determined by measuring the platelet activation (CD62P expression, platelet adhesion (Scanning Electron Microscopy, and the blood clotting time on these samples. Results: The films were compact and smooth and existed mainly in the form of anatase. By increasing the number of TiO2 thin layer, clotting time greatly extended, and the population of activated platelet and P-selectine expression changed according to the surface characteristics of each layer. Conclusion: The findings revealed that stainless steel 316L coated with nano-structured TiO2 layer improved blood compatibility, in terms of both blood platelet activity and coagulation cascade, which can decrease the thrombogenicity of blood contacting devices which were made from stainless steel.

Mohammadreza Foruzanmehr

2014-04-01

350

Surface charges of oxides and wettability: Application to TiO2-SiO2 composite films  

Science.gov (United States)

The super-hydrophilicity which can exist at the interface between oxides and aqueous solutions is able to sustain industrial and domestic applications. Several experimental results obtained on TiO2-SiO2 composite thin films via a sol-gel route have confirmed a natural and persistent super hydrophilicity under standard atmosphere. This property can be easily photo-regenerated after a long aging period in ambient atmosphere using a short UV illumination. The electrochemical double layer which classically exists between oxide surfaces and aqueous solution is unfavorable to high wettability properties of ideal flat surfaces. The present study indicates how the surface rugosity and the disjoining pressure caused by surface charges are able to explain the stability of a prewetting film. This film can withstand to vaporization in a weakly under saturated atmosphere, having a protective action despite a carbon contamination brought by standard atmosphere.

Joud, J.-C.; Houmard, M.; Berthomé, G.

2013-12-01

351

Effects of electron transfer between TiO2 films and conducting substrates on the photocatalytic oxidation of organic pollutants.  

Science.gov (United States)

TiO2 films on Al alloy (Al), indium-tin oxide glass (ITO/glass), and glass were prepared by a dip-coating method. ITO is found to have a higher work function, while the work function for Al is lower than that of TiO2 films. An electron transfer is indicated to occur in the interfaces between TiO2 films and conducting substrate Al or ITO, which results in an Ohm contact or Schottky barrier under the transient equilibrium UV radiation conditions. Photocatalytic measurements showed that the TiO2 films on Al have a higher activity for photocatalytic oxidation of C2H4, but the activity for photocatalytic degradation of oleic acid is lower as compared with TiO2 films on glass. Alternatively, TiO2 films on ITO give completely contrary photocatalytic performance to those on Al. These observations could be associated with the electron transfer, in which Al acts as an electron donor and offers electrons to TiO2, allowing photocatalytic oxidation of ethylene to proceed by the photogenerated electrons, while ITO could be an acceptor for the photogenerated electrons, which is beneficial to photocatalytic degradation of oleic acid by the photogenerated holes. This electron-transfer model could be extended to other photocatalytic systems. PMID:16821872

Dai, Wenxin; Wang, Xuxu; Liu, Ping; Xu, Yiming; Li, Guangshe; Fu, Xianzhi

2006-07-13

352

On the initial growth of atomic layer deposited TiO2 films on silicon and copper surfaces  

International Nuclear Information System (INIS)

Atomic layer deposition (ALD) of TiO2 using tetrakis(diethylamino)titanium precursor and H2O was studied on silicon and copper surfaces in order to examine differences in nucleation. Both surfaces were patterned on the same substrate to assure identical deposition conditions. Spectral ellipsometry, X-ray photoelectron spectroscopy and surface profilometry were used to probe nucleation phenomena, growth rates, and surface morphology on both surfaces. The TiO2 deposition on copper was found to exhibit a significant induction period of about 20–25 ALD cycles with no observable TiO2 during the first 10–15 cycles on the copper side; in contrast, no such inhibited growth was observed in the TiO2 deposition on silicon. This result opens up potential for selective ALD of TiO2 films on silicon-based substrates patterned with a metal without the use of a mask, a self-assembled monolayer or soft lithography which is impractical for some nanoscale semiconductor fabrication processes. After film nucleation, the TiO2 growth rate on both surfaces was found to be 0.10 nm/cycle. - Highlights: ? Study of initial growth of atomic layer deposited TiO2 films on Si and Cu surfaces. ? TiO2 deposition on copper is found to exhibit a significant induction period. ? Selective initial deposition on Si substrates patterned with Cu. ? Selective deposition without the use of masks, soft lithography or other monolayers.

2012-09-01

353

Selective detection of volatile organic compounds by spectral imaging of porphyrin derivatives bound to TiO2 porous films.  

Science.gov (United States)

In this work, the carboxylic acid derivatives of a free-base porphyrin, 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphyrin, and 10 of its metal derivatives (TCPPs) have been used for optical gas sensing. For this purpose, microstructured columnar TiO(2) thin films prepared by GAPVD (glancing angle physical vapor deposition) have been used as host materials for the porphyrins as they are non-dispersive and porous, allowing their use for UV-visible spectroscopy and gas sensing. The chemical binding between the dye molecules and the TiO(2) has been studied through infrared spectroscopy, and the obtained spectral changes have been found to be compatible with chelating and/or bidentate binding modes of the carboxylate groups on the TiO(2) surface. When hosted in the film, the UV-visible spectra of the porphyrins featured a blue shift and broadening of the Soret band with respect to the solution, which has been attributed to the formation of ?-? aggregates between porphyrin molecules. The composite porphyrin/TiO(2) films obtained from each of the 11 porphyrins have been exposed to 12 different volatile organic compounds (VOCs), and their respective gas-sensitive properties have been analyzed as a function of the spectral changes in their Soret band region in the presence of the analytes. The set of composite films has shown high selectivity to the analyzed volatile compounds. For each analyte, an innovative way of showing the different responses has been developed. By means of this procedure, an imagelike recognition pattern has been obtained, which allows an easy identification of every compound. The kinetics of the exposure to several analytes showed a fast, reversible and reproducible response, with response times of a few seconds, which has been attributed to both the sensitivity of the porphyrins and the high porosity of the TiO(2) films. Also, increasing concentrations of the analytes resulted in an increase in the magnitude of the response, indicating that the sensor behavior is also concentration-dependent. PMID:22985094

Roales, Javier; Pedrosa, José M; Castillero, Pedro; Cano, Manuel; Richardson, Tim H; Barranco, Ángel; González-Elipe, Agustín R

2012-10-24

354

Structural and Magnetic Properties of Fe-Doped Anatase TiO2 Films Annealed in Vacuum  

International Nuclear Information System (INIS)

Structural and magnetic properties of Fe-doped anatase TiO2 films fabricated by sol-gel spin coating are investigated. X-ray diffraction measurements reveal that Fe ions are incorporated into the TiO2 lattice. No ferromagnetism-related secondary phases and magnetic nanoparticles are observed in the films. The presence of electron paramagnetic resonance signals at g ? 2.0 supports oxygen vacancies and/or defects generated in the films after annealing in vacuum. Magnetic measurements indicate that Fe-doped anatase TiO2 films are ferromagnetic at room temperature. These observations suggest that oxygen vacancies and/or defects are energetically favorable for the long range Fe3+-Fe3+ ferromagnetic coupling in Fe-doped anatase TiO2 films

2009-09-01

355

Dye-sensitized solar cells based on double-layered TiO2 composite films and enhanced photovoltaic performance  

International Nuclear Information System (INIS)

Graphical abstract: Display Omitted Highlights: ? Double-layered DSSCs were fabricated based on TiO2 nanoparticles and hollow spheres. ? Morphology of film electrodes affects photovoltaic performance of DSSCs. ? Incorporation of TiO2 hollow spheres enhances conversion efficiency of DSSCs. ? DSSC of TiO2 nanoparticles/hollow spheres had the maximum conversion efficiency. - Abstract: Dye-sensitized solar cells (DSSCs) are fabricated based on double-layered composite films of TiO2 nanoparticles and hollow spheres. The photoelectric conversion performances of DSSCs based on nanoparticles/nanoparticles (PP), hollow spheres/hollow spheres (HH), hollow spheres/nanoparticles (HP), and nanoparticles/hollow spheres (PH) double-layered films are investigated, and their photo-electric conversion efficiencies are 4.33, 4.72, 4.93 and 5.28%, respectively. The enhanced performance of TiO2 nanoparticles/hollow spheres double-layered composite film solar cells can be attributed to the combined effect of following factors. The light scattering of overlayer hollow spheres enhances harvesting light of the DSSCs and the underlayer TiO2 nanoparticle layer ensures good electronic contact between film electrode and the F-doped tin oxide (FTO) glass substrate. Furthermore, the high surface areas and pore volume of TiO2 hollow spheres are respectively beneficial to adsorption of dye molecules and transfer of electrolyte solution.

2011-07-15

356

Aggregate formation of eosin-Y adsorbed on nanocrystalline TiO2 films  

Science.gov (United States)

We have studied the adsorption of eosin-Y on nanocrystalline TiO2 films with two different solvents namely acetonitrile (ACN) and ethanol (EtOH). A Langmuir-type adsorption isotherm was observed with ACN. In contrast, a Freundlich-type adsorption isotherm was observed with EtOH, suggesting that EtOH molecules co-adsorbed on TiO2 surface. Absorption spectra of the dye adsorbed films clearly show aggregate formation at high concentrations of dye in the solutions. From the analysis of the spectra, we conclude that head-to-tail type aggregates are observed with ACN, whereas various types of aggregates, including H-type and head-to-tail type aggregates, are observed with EtOH.

Yaguchi, Kaori; Furube, Akihiro; Katoh, Ryuzi

2012-11-01

357

Improved metal-insulator-transition characteristics of ultrathin VO2 epitaxial films by optimized surface preparation of rutile TiO2 substrates  

Science.gov (United States)

Key to the growth of epitaxial, atomically thin films is the preparation of the substrates on which they are deposited. Here, we report the growth of atomically smooth, ultrathin films of VO2 (001), only ˜2 nm thick, which exhibit pronounced metal-insulator transitions, with a change in resistivity of ˜500 times, at a temperature that is close to that of films five times thicker. These films were prepared by pulsed laser deposition on single crystalline TiO2(001) substrates that were treated by dipping in acetone, HCl and HF in successive order, followed by an anneal at 700-750 °C in flowing oxygen. This pretreatment removes surface contaminants, TiO2 defects, and provides a terraced, atomically smooth surface.

Martens, Koen; Aetukuri, Nagaphani; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.

2014-02-01

358

The Effect of Dye Density on the Efficiency of Photosensitization of TiO2 Films: Light-Harvesting by Phenothiazine-Labelled Dendritic Ruthenium Complexes  

Directory of Open Access Journals (Sweden)

Full Text Available A family of dendritic tris-bipyridyl ruthenium coordination complexes incorporating two or four carboxylate groups for binding to a TiO2 surface site and another dendritic linker between the metal complex and highly absorptive dyes were formulated as thin films on TiO2 coated glass. The family included phenothiazine-substituted dendrons of increasing structural complexity and higher optical density. The dye-loaded films were characterized by steady-state emission and absorption measurements and by kinetic studies of luminescence and transient absorption. Upon photoexcitation of the bound dyes, rapid electron injection into the metal oxide film was the dominant observed process, producing oxidized dye that persisted for hundreds of milliseconds. Complex decay profiles for emission, transient absorption, and optical bleaching of the dendritic dyes point to highly heterogeneous behavior for the films, with observed persistence lifetimes related directly to structurally enhance electronic coupling between the metal oxide support and the dendritic dyes.

Lin-Yong Zhu

2009-09-01

359

Photoinduced effects in TiO2 nanocrystalline films with different morphology  

International Nuclear Information System (INIS)

Research highlights: ? Raman spectra as a function of treatment temperature of the TiO2 films obtained from a solution prepared in presence of PEG 600 (left portion) and without PEG (right portion). - Abstract: The complex studies of photoinduced absorption, second harmonic generation and third harmonic generation were performed for TiO2 films of different morphology. In particular we have studied the influence of a bicolor laser beam treatment by a 300 mW green cw laser emitting at 532 nm on changes of absorption, birefringence and third harmonic generation on TiO2 films. We have performed the corresponding measurements using as a photoinducing light a glass erbium 10 ns pulsed laser with a fundamental wavelength of about 1540 nm together with its second harmonic generation (SHG) at 770 nm using the method of bicolor laser treatment and a frequency repetition of about 10 Hz. Varying the power density ratios between the fundamental and its SHG we have established the optimal conditions to achieve maximal photoinduced changes of absorption, birefringence and third harmonic generation (THG). We have detected changes of the birefringence and of the THG immediately after the laser treatment. We study an influence of the nanoparticle's sizes on the observed changes of the optical features. Additionally we have studied the role of different chemical treatment on the structural and optical parameters.

2010-10-22

360

Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV conjugated polymer to develop nanocomposite films for photovoltaic applications  

Science.gov (United States)

This study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different shapes (nanospheres, nanorods and nanorhombics) using oleic acid (OA) and oleyl amine (OM) as capping agents. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. It was found that the shape of NPs and the amount of OA and OM surfactants capped on their surface have an effect on their energy bandgap and also on the dispersion quality of MEH-PPV/TiO2 nanocomposites. Even though there was no evidence of chemical bonding between MEH-PPV matrix and TiO2 dispersed NPs, MEH-PPV/TiO2 nanocomposites showed very promising results for light absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs, which are two main characteristics for photovoltaic materials.

Mighri, F.; Duong, Vu Thi Thuy; On, Do Trong; Ajji, A.

2014-05-01

 
 
 
 
361

Enhancement of photoelectric catalytic activity of TiO2 film via Polyaniline hybridization  

International Nuclear Information System (INIS)

A Polyaniline (PANI)/TiO2 film coated on titanium foil was successfully prepared using the sol-gel method followed by a facile chemisorption. Compared with pristine TiO2, the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation rates of 2,4-dichlorophenol (2,4-DCP) with the PANI/TiO2 film were enhanced by 22.2% and 57.5%, respectively. 2,4-DCP can be mineralized more effectively in the presence of PANI/TiO2 film. The best PEC degradation efficiency of 2,4-DCP with the PANI/TiO2 film was acquired at an external potential of 1.5 V with a layer of 1 nm thick PANI. The PANI/TiO2 film was characterized by Raman spectra, Fourier transform infrared spectra (FT-IR), Auger electron spectroscopy (AES), and electrochemical analysis. These results indicated that there was a chemical interaction on the interface of PANI and TiO2. This interaction may be of significance to promote the migration efficiency of carriers and induce a synergetic effect to enhance the PC and PEC activities. - Graphical abstract: The effect of PANI content on 2,4-DCP degradation with initial concentration of 50 mg/L, external potential=1.5 V. Inset: degradation rate constants of various PANI/TiO2 films. Highlights: ? Polyaniline/TiO2 film was prepared using the sol-gel method followed by chemisorption. ? Photoelectrocatalytic degradation rate of 2,4-dichlorophenol was enhanced by 57.5%. ? The modification of Polyaniline to TiO2 film caused a rapid charge separation. ? Best degradation efficiency was acquired at 1.5 V with 1 nm thick PANI.

2011-06-01

362

Luminescence depolarization effects in protein-modified SiO2-TiO2 films doped with organic luminophores  

International Nuclear Information System (INIS)

Thin SiO2-TiO2 films functionalized with -SH groups were prepared by the sol-gel technique from tetraethoxysilane and (3mercaptopropyl)trimethoxysilane, or -NH2 groups from (3-aminopropyl)-triethoxysilane precursors. Labeled with fluorescein isothiocyanate (FITC), proteins, capable of selective bacterial endotoxins binding, were covalently attached to the films surfaces (via the -NH2 and -SH groups) in a way retaining their rotational freedom. The samples were incubated with selected bacterial endotoxins which bound to the immobilized, FITC-labeled proteins decreasing their rotational freedom. This effect has been detected as a change in the luminescence depolarization. The system based on this effect is proposed as a luminescence biosensor for the endotoxins recognition

2005-08-01

363

Transmission electron microscopy studies of atomic layer deposition TiO2 films grown on silicon  

International Nuclear Information System (INIS)

Transmission electron microscopy techniques have been used to characterise atomic layer deposition TiO2 films grown on silicon substrates after RCA and HF treatment. The influence of deposition temperature (250-350 deg. C) and substrate type on the film microstructure have been determined. The major influence of substrate type is to control nucleation of crystallisation. HF treated silicon, which was devoid of the native oxide layer, promoted a crystalline, island growth mode. The nucleation of crystalline particles at the onset of deposition resulted in films with very fine grain sizes (?20 nm). The RCA treated silicon, which was coated with amorphous native oxide, caused the growth of an initially amorphous TiO2 film, which crystallised once a critical film thickness had been exceeded. The major influence of temperature on the films grown on RCA treated silicon was to control nucleation of crystallisation within the amorphous layers, resulting in grain size refinement at higher deposition temperatures. Under the processing conditions used, other than the transient amorphous films formed on RCA treated silicon, anatase was the only phase formed. No evidence for preferred orientation was found

2003-09-22

364

Resistive and capacitive response of nitrogen-doped TiO2 nanotubes film humidity sensor  

International Nuclear Information System (INIS)

Dielectric oxides are traditionally used to fabricate resistive surface humidity-sensing devices, as well as capacitive sandwich-structured sensors. In the present work, relative humidity (RH) sensors were fabricated by employing vertically aligned TiO2 nanotubes array (TNA) film produced using electro-chemical anodization of Ti foil followed by a nitrogen-doping process, simultaneously showing resistive and capacitive humidity-sensing properties in the range of 11.3-93.6%. For the sample formed at optimized experimental conditions, the capacitance (CS) and resistance (RS) of the as-fabricated RH sensors made from nitrogen-doped TiO2 nanotubes film could be simultaneously obtained. Both the resistive and capacitive sensitivity (KR and KC) of the as-fabricated TiO2 nanotube RH sensors show distinct dependence on the frequency of alternating current (AC) voltage signal and RH. At higher water coverage, water-water interaction will result in lowering of the water dissociation barrier, leading to an increase of conductance. With the increase of RH, the polarization of as-adsorbed water molecules will also occur, causing a sharp increase of capacitance. For an explanation of the frequency response of both CS and RS, ionic transport, as well as the polarization effect, should be comprehensively considered. The changes of capacitance and resistance at different temperatures are plausibly caused by thermal expansion and surface state modification by adsorption and desorption of oxygen and water.

2011-01-14

365

Structure and Properties of La2O3-TiO2 Nanocomposite Films for Biomedical Applications  

Science.gov (United States)

The hemocompatibility of La2O3-doped TiO2 films with different concentration prepared by radio frequency (RF) sputtering was studied. The microstructures and blood compatibility of TiO2 films were investigated by scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible optical absorption spectroscopy, respectively. With the increasing of the La2O3 concentrations, the TiO2 films become smooth, and the grain size becomes smaller. Meanwhile, the band gap of the samples increases from 2.85 to 3.3?eV with increasing of the La2O3 content in TiO2 films from 0 to 3.64%. La2O3-doped TiO2 films exhibit n-type semiconductor properties due to the existence of Ti2+ and Ti3+. The mechanism of hemocompatibility of TiO2 film doped with La2O3 was analyzed and discussed.

Zhang, Lin; Sun, Zhi-Hua; Yu, Feng-Mei; Chen, Hong-Bin

2011-01-01

366

Effects of electron beam irradiation on the photoelectrochemical properties of TiO2 film for DSSCs  

International Nuclear Information System (INIS)

ABSTRACT: TiO2 has been widely utilized for various industrial applications such as photochemical cells, photocatalysts, and electrochromic devices. The crystallinity and morphology of TiO2 films play a significant role in determining the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, the preparation of nanostructured TiO2 films by electron beam irradiation and their characterization were investigated for the application of DSSCs. TiO2 films were exposed to 20–100 kGy of electron beam irradiation using 1.14 MeV energy acceleration with a 7.46 mA beam current and 10 kGy/pass dose rates. These samples were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. After irradiation, each TiO2 film was tested as a DSSC. At low doses of electron beam irradiation (20 kGy), the energy conversion efficiency of the film was approximately 4.0% under illumination of simulated sunlight with AM 1.5 G (100 mW/cm2). We found that electron beam irradiation resulted in surface modification of the TiO2 films, which could explain the observed increase in the conversion efficiency in irradiated versus non-irradiated films. - Highlights: ? The surface of TiO2 particles was modified by electron beam irradiation. ? The aggregation between each TiO2 particle was observed in the SEM images. ? Ti3+ state was enhanced due to the excess electron injection via electron beam irradiation. ? The power conversion efficiency of DSSCs was enhanced.

2012-08-01

367

Temperature field analysis of single layer TiO2 film components induced by long-pulse and short-pulse lasers  

International Nuclear Information System (INIS)

To study the differences between the damaging of thin film components induced by long-pulse and short-pulse lasers, a model of single layer TiO2 film components with platinum high-absorptance inclusions was established. The temperature rises of TiO2 films with inclusions of different sizes and different depths induced by a 1 ms long-pulse and a 10 ns short-pulse lasers were analyzed based on temperature field theory. The results show that there is a radius range of inclusions that corresponds to high temperature rises. Short-pulse lasers are more sensitive to high-absorptance inclusions and long-pulse lasers are more easily damage the substrate. The first-damage decision method is drawn from calculations.

2011-07-10

368

Growth and structural characterisation of vanadium oxide ultrathin films on TiO2 (110)  

DEFF Research Database (Denmark)

The research activity of our group in the last few years has mainly been devoted to the study of ultrathin vanadium oxide films deposited on a (110)-oriented TiO2 single crystal, in order to prepare systems which may be largely thought of as simplified models for the investigation of the structureyproperties relationships in real world catalysts, sensing and optical devices.The main objective of our work consists of setting up reproducible synthesis routes for the deposition of vanadium oxide ultrathin films on TiO2 (110), through strict control of the reaction parameters.The films obtained are then characterised from a chemical, electronic and structural point of view, and their properties are compared to those of their bulk-related phases.Results are presented concerning growth procedures and structural and electronic properties of vanadium oxide ultrathin films on titania, with a stoichiometry ranging from VO2, down to approximately VO.In particular, it will be shown that the oxidation product of metallic vanadium in an oxygen or water atmosphere (in the 10y6 mbar range) retains the rutile lattice structure typical of stoichiometric VO2, despite the increasing degree of oxygen defectiveness and the electronic properties, very similar to those pertaining to bulk V2O3.The peculiar behaviour of vanadium oxide on titania demonstrates how important the epitaxial influence of the substrate is on the nature of the overlayer.These results could represent a good starting point to understand why vanadium oxides on TiO2 show an enhanced catalytic activity and selectivity in many industrially relevant reactions. copyright 2001 Elsevier Science B.V. All rights reserved. Keyword: Titanium oxide,Photoelectron diffraction,Surface structure,Vanadium oxide,Single-crystal epitaxy,Ultrathin films,Photoelectron spectroscopy

Sambi, M.; Della Negra, Michela

2001-01-01

369

Enhanced visible-light photocatalytic activity of g-C3N4/TiO2 films.  

Science.gov (United States)

Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) catalyst films has been demonstrated in this present work. The g-C3N4/TiO2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO2 nanoparticles in Ar gas flow. The g-C3N4 contents in the g-C3N4/TiO2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO2 with g-C3N4 and the best degradation performance of ~70% was obtained from 50 wt% g-C3N4 loading content. Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interfacial electron transfer between TiO2 and g-C3N4 of the g-C3N4/TiO2 composite film. Based on the obtained results, the possible MB degradation mechanism is ascribed mainly to the generation of active species induced by the photogenerated electrons. PMID:24407703

Boonprakob, Natkritta; Wetchakun, Natda; Phanichphant, Sukon; Waxler, David; Sherrell, Peter; Nattestad, Andrew; Chen, Jun; Inceesungvorn, Burapat

2014-03-01

370

Post-annealing of CdS/ZnS-assembled TiO2 films for photoelectrochemical solar cells  

Science.gov (United States)

CdS/ZnS-assembled TiO2 films are annealed at 350 °C in an inert Ar ambient before and after deposition of the ZnS overlayer and are denoted as the types I and II, respectively. As-grown and the annealed CdS-quantum-dot (QD)-assembled TiO2 samples without a ZnS overlayer were also prepared for comparison. Annealing of CdS-QD-assembled TiO2 without ZnS significantly reduced the electron lifetime due to the coalescence of CdS QDs on the TiO2 surface. The electron lifetime of the annealed CdS-QD-assembled TiO2 was recovered because of ZnS overlayer due to its being an intermediate layer and to the energy barrier effects at the TiO2/electrolyte and the CdS QD/electrolyte interfaces. The resultant photoelectrochemical solar cell (PEC) with the type I film exhibited better energy conversion efficiency than the PECs without the ZnS. The cell performance of the PEC with the type II film was further improved, as compared to that with the type I film. This can be attributed to the additional effect (improved interfacial contact at the CdS/ZnS interface) of the postannealing after the formation of the ZnS overlayer.

Jung, Sung Woo; Park, Min-Ah; Lee, Soo-Yong; Kim, Jae-Hong; Ahn, Kwang-Soon; Seo, Myeong-Soo; Kim, Hyunsoo; Choi, Chel-Jong; Kang, Soon-Hyung

2013-12-01

371

Layer-by-layer structured films of TiO2 nanoparticles and poly(acrylic acid) on electrospun nanofibres  

Science.gov (United States)

We report a new approach for fabricating layer-by-layer (LBL) structured ultrathin hybrid films on electrospun nanofibres. Oppositely charged anatase TiO2 nanoparticles and poly(acrylic acid) (PAA) were alternately deposited on the surface of negatively charged cellulose acetate (CA) nanofibres using the electrostatic LBL self-assembly technique. The fibrous mats were characterized by wide-angle x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller (BET) surface area techniques. The crystalline phase of anatase TiO2 remained unchanged in the resultant TiO2/PAA films coated on CA fibrous mats. Moreover, the TiO2/PAA film coated fibres showed rough surfaces with grains due to the deposition of aggregated TiO2 particles. The average diameter of the fibres increased from 344 to 584 nm and the BET surface area of the fibrous mats increased from 2.5 to 6.0 m2 g-1 after coating with five bilayers of TiO2/PAA films.

Ding, Bin; Kim, Jinho; Kimura, Eiji; Shiratori, Seimei

2004-08-01

372

Anatase phase stability and doping concentration dependent refractivity in codoped transparent conducting TiO2 films  

International Nuclear Information System (INIS)

Nb0.06SnxTi0.94-xO2 (x ? 0.3) thin films were grown by a pulsed-laser deposition method with varying Sn concentration. Through a combinatorial technique, we find that Sn concentration can reach a maximum of about x = 0.3 while maintaining the stable anatase phase and epitaxy. A doping concentration dependence of the refractivity is revealed, in which refractivity reduction at a wavelength of ? = 500 nm is estimated to be 12.4% for Nb0.06Sn0.3 Ti0.64O2 thin film. Sn doping induced band-gap blue shift can be contributed to the mixing of extended Sn 5s orbitals with the conduction band of TiO2. Low resistivity on the order of 10-4 ? cm at room temperature and high internal transmittance of more than 95% in the visible light region are exhibited for Nb0.06Snx Ti0.94-xO2 thin films (x ? 0.2). Optical and transport analyses demonstrate that doping Sn into Nb0.06 Ti0.94O2 can reduce the refractivity while maintaining low resistivity and high transparency

2007-10-07

373

Preparation and characterization of amine-functionalized SiO2/TiO2 films for formaldehyde degradation  

International Nuclear Information System (INIS)

This paper investigated the gaseous formaldehyde degradation by the amine-functionalized SiO2/TiO2 photocatalytic films for improving indoor air quality. The films were synthesized via the co-condensation reaction of methyltrimethoxysilane (MTMOS) and 3-aminopropyltrimethoxysilane (APTMS). The physicochemical properties of prepared photocatalysts were characterized with N2 adsorption/desorption isotherms measurement, X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FT/IR). The effect of amine-functional groups and the ratio of MTMOS/APTMS precursors on the formaldehyde adsorption and photocatalytic degradation were investigated. The results showed that the formaldehyde adsorption and photocatalytic degradation of the APTMS-functionalized SiO2/TiO2 film was higher than that of SiO2/TiO2 film due to the surface adsorption on amine sites and the relatively high of the specific surface area of the APTMS-functionalized SiO2/TiO2 film (?15 times higher than SiO2/TiO2). The enhancement of the formaldehyde degradation of the film can be attributed to the synergetic effect of adsorption and subsequent photocatalytic decomposition. The repeatability of photocatalytic film was also tested and the degradation efficiency was 91.0% of initial efficiency after seven cycles.

2009-09-15

374

Enhancement of the photoelectric performance of dye-sensitized solar cells using Ag-doped TiO2 nanofibers in a TiO2 film as electrode  

Science.gov (United States)

For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO2 nanofiber [TN] and Ag-doped TiO2 nanofiber [ATN] have been extended to be included in TiO2 films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO2 photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO2 films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced.

2012-01-01

375

Solid-state source of atomic oxygen for low-temperature oxidation processes: application to pulsed laser deposition of TiO2:N films.  

Science.gov (United States)

An atomic oxygen (AO) source has been redesigned to coordinate with a pulsed laser deposition system and used to grow nitrogen-doped TiO(2) films by deposition of TiN and simultaneous irradiation of the substrate with AO. The AO source uses an incandescently heated thin tube of zirconia as an oxygen permeation media to generate pure AO of low kinetic energy. The emission flux is calibrated using a silver-coated quartz crystal microbalance. The thin shape of the probe and transverse emission geometry of this emission device allow the emission area to be positioned close to the substrate surface, enhancing the irradiation flux at the substrate. AO irradiation is crucial for formation of TiO(2) phases via oxidation of the deposited TiN laser plume, and is effective for decrease of the substrate temperature for crystallization of anatase phase to as low as around 200 °C. PMID:22380103

Ojima, Daiki; Chiba, Tetsuya; Shima, Kazunari; Hiramatsu, Hidenori; Hosono, Hideo; Hayashi, Katsuro

2012-02-01

376

TiO2-x films prepared by ion beam assisted deposition  

International Nuclear Information System (INIS)

TiO2-x films were prepared by ion beam assisted deposition on an EATON Z-200 system, during which concurrent electron beam evaporation of titanium and bombardment with an inert gas ion beam were carried out in an O2 atmosphere. Xe+ and Ne+ ions with different current density and incident angles were used. The films were investigated using X-ray diffraction (XRD), glancing incident X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). RBS analysis shows that the films are nearly stoichiometric. XPS measurements reveal that the surface was fully oxidized, but Ti2+, Ti3+ and Ti4+ coexist on the Ar+-sputtered surface. XRD and GIXRD analyses show that almost all the films have rutile-type structure and (2 0 0) preferred orientation. After annealing the 2? angle shift to higher degrees and the (2 0 0) peak intensity increases, which means better crystallization and orientation

2000-06-02

377

HydrothermalPreparation of TiO2 Films on Titanium Sponge Substrate  

Directory of Open Access Journals (Sweden)

Full Text Available Anatase―type titanium dioxide filmson the titanium sponge substrate with grain size of about 0.5 m m were prepared by onestep hydrothermal treatment using hydrogen peroxide as oxidant and potassiumhydroxide as mineralizer, and the photocatalytic property of the as―preparedfilms was determined by the degradation of the methylene blue under irradiationof UV light. The effects of the concentration of potassium hydroxide on the crystalphase, morphology and photocatalytic property of titanium dioxide films were alsostudied. The results showed that potassium hydroxide promoted the crystallizationof thetitaniumdioxide. And with a concentration of 0.12mol/L of potassium hydroxide solution,the film had the best photocatalytic property with a 95% degradation rate after45 min UV―irradiation. The as―prepared TiO2 films could be easilyrecycled and the photocatalytic property of recycled films was not markedlydecreased.

ZHAO Yun-Yun, XU Hua-Rui, ZHU Gui-Sheng

2010-07-01

378

Influence of the Substrate Temperature on the Properties of Nb―doped TiO2 Films Deposited by DC Magnetron Sputtering  

Directory of Open Access Journals (Sweden)

Full Text Available Nb―doped (2.5wt%) TiO2 thin films was deposited on glass substrate by DC magnetron sputtering from a ceramic target and the films thickness was controlled in the range from 300 nm to 350 nm. The structure, surface morphology and optical properties of the films deposited at different substrate temperatures were investigated by X―ray diffraction, scanning electron microscope, and optical transmission spectroscope. The films deposited at 150¡?250¡?nd 350¡?ere amorphous, anatase and rutile, respectively. The grain size of the typical anatase film deposited at 250¡?eached the maximum of 32 nm. The roughness of the films decreased and their density increased with the rising of substrate temperature. The average optical transmittance of films were around 70% when the substrate temperatures were below 250¡?As the substrate temperature were risen to 350¡?the films’ transmittance dropped to 59%. It indicated that the transmittance of visible light was hindered by the rutile phase in the Nd―doped TiO2 films. The optical band gap of the films were in the range from 3.68 eV to 3.78 eV, and the optical band gap of the typical anatase film deposited at 250¡?eached the highest value of 3.78 eV.

HUANG Shuai, LI Chen-Hui, SUN Yi-Hua, KE Wen-Ming

2012-01-01

379

Solvent Effect on the Electrical and Optical Properties of Nano composite MEH-PPV: TiO2 Films for Organic Solar Cells Applications  

International Nuclear Information System (INIS)

The influence of organic solvent on the electrical and optical properties of photodiodes based on poly[2-methoxy,5-(2'- ethylhexyloxy)-1,4-phenylene vinylene) MEHPPV) and nano-TiO2 nano composite are investigated. The films were prepared from TiO2 dispersed in MEH-PPV solutions in toluene, tetrahydrofuran (THF), xylene, chloroform and 1,3-dichlorobenzene (1,3- DCB) solvents at concentration of 20 mg/ 20 ml. The electrical properties of the MEH-PPV: TiO2 nano composite thin films were measured by solar simulator in dark and under illumination condition while the characterization of optical properties has using UV-VIS spectrophotometer to evaluate the absorbance. The solvent of 1,3-DCB shows a greater conductivity with 33.82x104 S.m-1 without photo response under illumination. (author)

2011-07-04

380

Growth of nanocrystalline TiO2 films by pulsed-laser-induced liquid-deposition method and preliminary applications for dye-sensitized solar cells  

Science.gov (United States)

A novel technique, the pulsed-laser-induced liquid-deposition (PLLD) method, has been employed to grow nanocrystalline TiO2 films on fluorine-doped tin-oxide-coated (FTO) glass substrates at room temperature. The PLLD method was implemented by directing a pulsed laser into a liquid precursor and depositing the photosynthesized nanocrystalline TiO2 on an FTO glass substrate immersed in the liquid precursor. The as-grown nanocrystalline TiO2 films were found to have a rutile crystal structure and consist of a number of flower-like TiO2 crystal units arrayed together on the FTO glass substrate. Each of the flower-like TiO2 crystal units was composed of many nanostructured TiO2 whiskers, and their building blocks were found to be bundles of TiO2 nanorods with diameter of about 5 nm. The growth of these TiO2 nanorods is highly anisotropic, with the preferential growth direction along [001]. As-grown nanocrystalline TiO2 films were annealed at 450°C in air for 30 min for the applications of dye-sensitized solar cells, and the nanostructured characteristics with good porosity were preserved after annealing. A preliminary dye-sensitized solar cell was built based on the annealed nanocrystalline TiO2 film. The results suggest that the PLLD method is a promising technique for growing nanocrystalline TiO2 films for photovoltaic applications.

Wang, Guo-Bing; Fu, Min-Gong; Lu, Bin; Du, Guo-Ping; Li, Li; Qin, Xiao-Mei; Shi, Wang-Zhou

2010-09-01

 
 
 
 
381

Photocatalytic and antibacterial properties of medical-grade PVC material coated with TiO2 film.  

Science.gov (United States)

The TiO(2) film was coated on poly vinyl chloride (PVC) surface by dip-coating process from TiO(2)-PVC-THF suspension. The morphology and crystal structure of the as-synthesized samples were characterized by SEM and XRD. The photocatalytic properties were measured by the photodegradation reaction of RhB and the anti-adhesion and anti-bacteria for Escherichia coli. The results show that the resultant TiO(2) film is well-conglutinated on PVC surface and has the same crystal structure as the original TiO(2) powder. The TiO(2)/PVC shows excellent photocatalytic activity for the degradation of aqueous RhB and the activity increases with increasing reaction time and tends toward stable after accumulative illumination for 11.5 h. The TiO(2) film shows good bacterial anti-adhesion activity following photo-activation and sterilization property under UV irradiation. The E. coli can be killed completely after UV irradiation for 1.5 h. PMID:18506814

Lin, Huaxiang; Xu, Ziting; Wang, Xuxu; Long, Jinlin; Su, Wenyue; Fu, Xianzhi; Lin, Qun

2008-11-01

382

Study on TiO2-doped Ge2Te3 films for phase-change memory application  

International Nuclear Information System (INIS)

The phase-change characteristics of Ge2Te3 films for phase-change random access memory applications were investigated by doping with TiO2 using magnetron cosputtering. The first and the second phase transitions, which corresponded to the crystallizations of GeTe and Te, occurred at around 210 0C and 225 0C for the Ge2Te3 film, respectively. The incorporation of TiO2 suppressed the crystallization of GeTe and held back the phase transition induced by the Te. The precipitation of aggregated GeTe from Ge2Te3-TiO2 was observed at the annealing temperature of 400 0C. The resistance ratio between RESET and SET states exceeded two orders of magnitude. Compared with Ge2Sb2Te5-based cell device, the Ge2Te3-TiO2 film-based ones had a lower power consumption. The reversible phase change could be accomplished by the electric pulse duration of 50 ns for Ge2Te3-TiO2 with 15 at% TiO2-based cell device.

2011-04-13

383

Synthesis and Characterization of Filtered-cathodic-vacuum-arc-deposited TiO2 Films for Photovoltaic Applications  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) is well-known as a photovoltaic and photocatalytic material. For improvement in the dye-sensitized solar cell (DSSC) performance efficiency, the photocatalyst TiO2 layer would be desired in nanoporous anatase. In this research, TiO2 films were synthesized on glass or p-type silicon substrate using our in-house Filtered Cathodic Vacuum Arc Deposition (FCVAD) system. The deposition was operated at varied oxygen (O2) partial pressures of 10?4, 10?3, 10?2 to 10?1 torr with fixed 0 or 250-V bias and 600-V arc for 10 or 20 minutes. The film transparency increased with increasing of the O2 pressure, indicating increase in the structure required for applications in dye-sensitized solar cells. The films were characterized using the Energy-Dispersive X-ray spectroscopy (EDS) and Raman spectroscopy techniques. The EDS confirmed that the transparent deposited films contained stoichiometric titanium and oxygen under the medium O2 pressure. Raman spectra confirmed that the films were TiO2 containing some rutile but no anatase which needed annealing to form. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used for evaluation of the film's surface morphology and thickness. The result showed that increasing of the O2 pressure decreased the thickness to a nanoscale but increased the amount of TiO2.

2013-04-10

384

Optical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol-gel method  

Science.gov (United States)

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films.

Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

2013-12-01

385

Structural Control of Hierarchically-Ordered TiO2 Films by Water for Dye-Sensitized Solar Cells.  

Science.gov (United States)

A facile way of controlling the structure of TiO2 by changing the amount of water to improve the efficiency of dye-sensitized solar cells (DSSCs) is reported. Hierarchically ordered TiO2 films with high porosity and good interconnectivity are synthesized in a well-defined morphological confinement arising from a one-step self-assembly of preformed TiO2 (pre-TiO2 ) nanocrystals and a graft copolymer, namely poly(vinyl chloride)-g-poly(oxyethylene methacrylate). The polymer-solvent interactions in solution, which are tuned by the amount of water, are shown to be a decisive factor in determining TiO2 morphology and device performance. Systematic control of wall and pore size is achieved and enables the bifunctionality of excellent light scattering properties and easy electron transport through the film. These properties are characterized by reflectance spectroscopy, incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy analyses. The TiO2 photoanode that is prepared with a higher water ratio, [pre-TiO2 ]:[H2 O]=1:0.3, shows a larger surface area, greater light scattering, and better electron transport, which result in a high efficiency (7.7?%) DSSC with a solid polymerized ionic liquid. This efficiency is much greater than that of commercially available TiO2 paste (4.0?%). PMID:24816729

Ahn, Sung Hoon; Kim, Dong Jun; Roh, Dong Kyu; Chi, Won Seok; Kim, Jong Hak

2014-06-23

386

High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance  

DEFF Research Database (Denmark)

We report on high-quality polycrystalline Fe-doped TiO2 (Feâ??TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material for photovoltaic and photocatalysis applications can be controlled by adjusting the electrolyte composition. Compared to Fe-doped TiO2 films prepared with traditional phosphate- or silicate-based electrolytes, our newly synthesised Feâ??TiO2 films contain solely Fe dopants, which results in excellent photocatalytic and photovoltaic performance under visible light irradiation.

Su, Ren; Bechstein, Ralf

2012-01-01

387

Consequences of niobium doping for the ferromagnetism and microstructure of anatase Co: TiO2 films  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It is shown that dilute niobium doping has significant effect on the ferromagnetism and microstructure of dilutely cobalt-doped anatase TiO2 films. Epitaxial films of anatase TiO2 with 3% Co, without and with 1% niobium doping were grown by pulsed-laser deposition at 875 C at different oxygen pressures. For growth at 10^{-5} Torr niobium doping suppresses the ferromagnetism, while it enhances the same in films grown at 10^{-4} Torr. High-resolution Z-contrast Scanning Transm...

Zhang, S. X.; Ogale, S. B.; Fu, L. F.; Dhar, S.; Kundaliya, D. C.; Ramadan, W.; Browning, N. D.; Venkatesan, T.

2006-01-01

388

Soporte de Nuevas Películas de TiO2 y TiO2/SiO2 sobre Gránulos de Poliéster para Aplicación en Fotocatálisis / Support of New TiO2 and TiO2/SiO2 Films on Polyester Granules for Photocatalytic Applications  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Películas de TiO2 o TiO2/SiO2 fueron soportadas sobre gránulos de poliéster usando mecanismos de difusión y posterior tratamiento térmico a 100ºC. Se emplearon dos clases de geles. El primero fue preparado usando diferentes cantidades de TiO2, cloruro de metileno y silicona líquida. El segundo fue o [...] btenido por medio del método sol-gel, empleado para producir una matriz de sílice a partir de la hidrólisis el tetraetilo ortosilicato, en un medio orgánico de 2-propanol, en el cual se dispersó el fotocatalizador. Los precursores de cada sistema fueron agregados en diferentes relaciones para determinar su influencia en la estabilidad, propiedades y fotoactividad de las películas. La actividad fotocatalítica fue evaluada en la fotodegradación de metanol en fase gaseosa. Los resultados muestran la producción de materiales con alta resistencia, funcionalidad y actividad así como una fuerte relación entre la actividad fotocatalítica con las propiedades fisicoquímicas. Abstract in english Films of TiO2 and of TiO2/SiO2 were supported on polyester granules using a diffusion mechanism and a posterior thermal treatment to 100ºC. Two kinds of gels were used. The first one was prepared using different amounts of TiO2, methylene chloride and liquid silicone. The second one used the sol-gel [...] method to produce a silica matrix by adding tetraethyl orthosilicate, water and 2- propanol. After that the photocatalyst was dispersed in the gel. The precursors of each system were added in different amounts to determine their influence in the stability, properties and photoactivity of the films. The photocatalytic activity was tested in the methanol photodegradation in gas phase. The results show the production of materials with high resistance, functionality and activity as well as a strong dependence between the photoca