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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

Photocatalytic TiO2 thin films prepared via a high-pressure crystallization process  

International Nuclear Information System (INIS)

[en] Titania thin films with high photocatalytic activity are successfully synthesized by combining the metalorganic deposition method (MOD) and the high-pressure crystallization (HPC) process. The crystallization temperature of anatase-type TiO2 films is significantly reduced to as low as 150 deg. C. TiO2 thin films with crack-free surface and uniform morphology are obtained. The diffusion of silicon species from substrates into TiO2 films is effectively suppressed. The HPC-derived TiO2 thin films are demonstrated to have higher photocatalytic activity than those prepared via the conventional annealing process

2004-10-15

3

Preparation, characterization, and photocatalytic activity of mesoporous TiO2 thin films.  

UK PubMed Central (United Kingdom)

Cubic-based ordered mesoporous TiO2 thin films were prepared by an evaporation-induced self-assembly method through a carefully controlling the hydrolysis/condensation conditions. The obtained sample exhibits mesoporous structure with a narrow pore size distribution. The TiO2 thin films have thick inorganic walls composed of nanocrystalline anatase. A reasonable explanation is also proposed to elucidate the formation of thick and stable mesoporous TiO2 films. The mesoporous TiO2 exhibits good photocatalytic activity. Nearly all the methyl orange has been degraded by the mesoporous TiO2 calcined at 500 degrees C.

Wang J; Li H; Li H; Wang H; Cai Q

2013-02-01

4

Preparation, characterization, and photocatalytic activity of mesoporous TiO2 thin films.  

Science.gov (United States)

Cubic-based ordered mesoporous TiO2 thin films were prepared by an evaporation-induced self-assembly method through a carefully controlling the hydrolysis/condensation conditions. The obtained sample exhibits mesoporous structure with a narrow pore size distribution. The TiO2 thin films have thick inorganic walls composed of nanocrystalline anatase. A reasonable explanation is also proposed to elucidate the formation of thick and stable mesoporous TiO2 films. The mesoporous TiO2 exhibits good photocatalytic activity. Nearly all the methyl orange has been degraded by the mesoporous TiO2 calcined at 500 degrees C. PMID:23646668

Wang, Jinshu; Li, Hui; Li, Hongyi; Wang, Hong; Cai, Qian

2013-02-01

5

TiO2 thin film deposition by chemical methods  

Science.gov (United States)

Mesoporous nanocrystalline TiO2 dye sensitized solar cells was obtained by the sol-gel process in an aqueous solution using the titanium diethanolamine complex as the precursor and the spin coating technique to obtain TiO2 films on ITO (Indium tin oxide) glass substrates. TG - DTA, BET, FT-IR, UV - VIS, SEM, Raman spectroscopy, X-ray diffraction techniques, have been used to investigate the chemical and physical changes during the sol - gel process and the characteristics of the TiO2 powder precursor.

Suciu, R.-C.; Ro?u, M. C.-; Marian, I.; Silipa?, T. D.; Varodi, C.; Popa, A.; Mihe?, M.; Indrea, E.

2012-02-01

6

Photocatalytic properties of nanocrystalline TiO2 thin films doped with Tb  

Science.gov (United States)

In this work photocatalytic properties of TiO2 thin films doped with different amount of Tb have been described. Thin films were prepared by high energy reactive magnetron sputtering process. Comparable photocatalytic activity has been found for all doped TiO2 thin films, while different amounts of Tb dopant (0.4 and 2.6 at. %) results in either an anatase or rutile structure. It was found that the terbium dopant incorporated into TiO2 was also responsible for the amount of hydroxyl groups and water particles adsorbed on the thin film surfaces and thus photocatalytic activity was few times higher in comparison with results collected for undoped TiO2 thin films.

Wojcieszak, Damian; Kaczmarek, Danuta; Domaradzki, Jaroslaw; Prociow, Eugeniusz L.; Morawski, Antoni W.; Janus, Magdalena

2011-04-01

7

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

International Nuclear Information System (INIS)

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 scanning 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.

2012-01-31

8

Orientated anatase TiO2 nanocrystal array thin films for self-cleaning coating.  

UK PubMed Central (United Kingdom)

We developed a simple method to synthesize TiO2 nanowire arrays with nearly 100% exposed {001} facets. The coating exhibits good transparency. The thin films of TiO2 nanowire arrays display a very good photocatalytic degradation of dye molecules and good durability. Based on the above features, the TiO2 nanowire array coating is advantageous for self-cleaning coating.

Zhao Z; Tan H; Zhao H; Li D; Zheng M; Du P; Zhang G; Qu D; Sun Z; Fan H

2013-09-01

9

Structural and optical properties of electrohydrodynamically atomized TiO2 nanostructured thin films  

Science.gov (United States)

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

10

PHOTOCATALYTIC PROPERTIES OF Cr DOPED TiO2–SiO2 NANOSTRUCTURE THIN FILM  

Directory of Open Access Journals (Sweden)

Full Text Available Cr doped TiO2–SiO2 nanostructure thin film on glass substrates was prepared by a sol-gel dip coating method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer were used to characterize the structural, chemical and optical properties of the thin film. The XRD showed that thin films contain only anatase phase. FE-SEM images illustrated that anatase average crystallite size in the pure TiO2 and Cr doped TiO2–SiO2 thin films are 15 nm and 10 nm, respectively. XPS spectra confirmed the presence of Cr3+ in the thin film. UV-vis absorption spectra indicated that absorption edge in Cr doped TiO2–SiO2 thin film shifted to the visible light region. The photocatalytic results pointed that Cr doping in TiO2–SiO2 improved decoloring rate of methyl orange in comparison to pure TiO2 thin film.

Akbar Eshaghi; Ameneh Eshaghi

2012-01-01

11

Nanocrystalline TiO2 Thin Films: Microstructural, Optical and Gas Sensing Properties  

Science.gov (United States)

Nanocrystalline titanium oxide thin films have been deposited by spin coating technique and then have been analyzed to test their application in NH3 gas-sensing technology. The X-ray diffraction measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and rutile phase structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine Gas sensing properties showed that TiO2 films were sensitive as well as fast in responding to NH3. A high sensitivity for ammonia indicates that the TiO2 films are selective for this gas.

Pawar, S. G.; Patil, S. L.; Chougule, M. A.; More, P. D.; Godse, P. R.; Pawar, S. A.; Patil, V. B.

2011-10-01

12

Synthesis of semicrystallized mesoporous TiO2 thin films using triblock copolymer templates  

International Nuclear Information System (INIS)

Self-assembled mesoporous TiO2 thin films have been synthesized by sol-gel method using amphiphilic triblock copolymer as a template under acidic conditions. The samples were characterized by small angle X-ray diffractometry (SAXRD), thermogravimetry-differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), N2 adsorption and field emission scanning electron microscopy (FE-SEM). The structural characteristic of mesoporous TiO2 thin films strongly depends on the pH values of precursor solution, heat treatment conditions, and the condensation of templates. It has been proven that the framework of obtained films consisted of TiO2 nanocrystallites

2003-06-10

13

TiO2/PANI And MWNT/PANI Composites Thin Films For Hydrogen Gas Sensing  

International Nuclear Information System (INIS)

[en] The MWNT and TiO2 doped Polyaniline (PANI) composites were synthesized by In-situ chemical oxidative polymerization method at low temperature. The MWNT/PANI and TiO2/PANI composite thin films were prepared using spin coating method onto finger type interdigited electrodes to develop the chemiresistor type gas sensor for hydrogen gas sensing application. It was observed that the MWNT and TiO2 doped PANI composite thin films show a higher response in comparision to neat PANI. The structural and morphological properties of these composite films were characterized by X-Ray differaction (XRD) pattern and sccaning electrone microscopy (SEM) respectively.

2010-12-01

14

Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping  

Directory of Open Access Journals (Sweden)

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

15

Improvement of optical properties of TiO2 thin film treated with electron beam.  

UK PubMed Central (United Kingdom)

Nanocrystalline titanium dioxide (TiO2) thin films on silicon wafer substrates were prepared by sol-gel spin coating process. The prepared thin films were treated with electron beam (1.1 MeV, 300 kGy) at air atmosphere. The effects of electron-beam (EB) irradiation on the structural and optical properties of the TiO2 thin films were investigated. The structures of all the TiO2 thin films by XRD analysis showed an anatase phase, and the phase remained unchanged within the investigating range of EB treatment. The thickness of the titania thin film decreased slightly with EB treatment whereas the porosity increased. The EB treatment of TiO2 thin film can increase the proportion of Ti3+ in Ti2p at the thin film surface. The optical transmittance of the film in the wavelength ranges of above 380 nm increased after the EB treatment while its refractive index decreased with increasing EB dose. Therefore, improvement of the optical properties could be due to the change in both surface chemistry and morphology of the TiO2 thin films affected by EB irradiation.

Shin JH; Lee BC; Woo HG; Hwang KH; Jun J

2013-03-01

16

Preparation and antibacterial behavior of Fe3+-doped nanostructured TiO2 thin films  

International Nuclear Information System (INIS)

[en] Fe3+-doped nanostructured TiO2 thin films with antibacterial activity were prepared on soda-lime-silica glass slides by using sol-gel technology. Water containing Escherichia coli K-12 with TiO2 thin films in was exposed to low intensity fluorescent light and antibacterial efficiency was evaluated with spread plate techniques. The films are porous and have anatase phase. Iron ions increased luminous energy utilization as the absorption edge of the Fe3+-doped film has a red shift compared to that of the pure TiO2 film in the UV-VIS absorption spectrum. The bacterial removal efficiency reached 95% at the optimum concentration of iron ion (about 0.5% (mol)) after 120 min irradiation. The antibacterial behavior of the doped TiO2 films was explicitly observed using scanning electron microscopy and cell wall damage was found

2008-06-02

17

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

18

Fabrication and characterization of nano TiO2 thin films at low temperature  

International Nuclear Information System (INIS)

Anatase TiO2 thin films were successfully prepared on glass slide substrates via a sol-gel method from refluxed sol (RS) containing anatase TiO2 crystals at low temperature of 100 deg. C. The influences of various refluxing time on crystallinity, morphology and size of the RS sol and dried TiO2 films particles were discussed. These samples were characterized by infrared absorption spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission-scanning electron microscopy (FE-SEM) and UV-vis absorption spectroscopy (UV-vis). The photocatalytic activities of the TiO2 thin films were assessed by the degradation of methyl orange in aqueous solution. The results indicated that titania films thus obtained were transparent and their maximal light transmittance exceeded 80% under visible light region. The TiO2 thin films prepared from RS-6 sol showed the highest photocatalytic activity, when the calcination temperature is higher than 300 deg. C. The degradation of methyl orange of RS-6 thin films reached 99% after irradiated for 120 min, the results suggested that the TiO2 thin films prepared from RS sol exhibited high photoactivities

2006-09-14

19

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

20

Controlling the particle size of nanobrookite TiO2 thin films  

International Nuclear Information System (INIS)

Highlights: ? Nanobrookite TiO2 films were deposited on glass substrates by spin-coating method. ? We produced the pure nanobrookite films using titanium butoxide and acetic acid. ? Particle size of the TiO2 films was controlled by volume ratios of water:acid. ? We determined that it is possible to obtain the films with single orientation. ? Particle sizes of the TiO2 films decrease with the decreasing water:AcAc volume ratio. ? It has been found that the spectrum red-shifts with increasing water concentration. - Abstract: In this study, pure nanobrookite TiO2 thin films were successfully deposited on glass substrates with the spin-coating method using titanium butoxide and acetic acid. The particle size of TiO2 films was controlled by the water:AcAc volume ratio. This study shows that it is possible to obtain single oriented pure brookite films. The structural and optical properties of the nanobrookite TiO2 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), spectrophotometer (NKD), and Fourier transform infrared spectrometer (FTIR).

2011-08-11

 
 
 
 
21

Synthesis of nanodimensional TiO2 thin films using energetic ion beam  

International Nuclear Information System (INIS)

Nanophases of TiO2 are achieved by irradiating polycrystalline thin films of TiO2 by 100 MeV Au ion beam at varying fluence. The surface morphology of pristine and irradiated films is studied by atomic force microscopy (AFM). Phase of the film before and after irradiation is identified by glancing angle X-ray diffraction (GAXRD). The blue shift observed in UV-vis absorption edge of the irradiated films indicates nanostructure formation. Electron spin resonance (ESR) studies are carried out to identify defects created by the irradiation. The nanocrystallisation induced by SHI irradiation in polycrystalline thin films is studied.

2008-01-01

22

A chemical route to room-temperature synthesis of nanocrystalline TiO2 thin films  

International Nuclear Information System (INIS)

[en] A lot of methods are developed for the deposition of TiO2 thin films; however, in each of these methods as-deposited films are amorphous and need further heat treatment at high temperature. In the present article, a chemical bath deposition (CBD) method was used for the preparation of TiO2 thin films. We investigated nanocrystalline TiO2 thin films using CBD at room temperature onto glass and ITO coated glass substrate. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The chemically synthesized films were nanocrystalline and composed of crystal grains of 2-3 nm

2005-06-15

23

Magneto-optical Kerr rotation in amorphous TiO2/Co magnetic semiconductor thin films  

International Nuclear Information System (INIS)

TiO2/Co thin films were prepared on glass substrates under thermal non-equilibrium condition by alternately sputtering very thin TiO2 and Co layers for 60 periods. Microstructure and composition analyses by X-ray diffraction, transmission electron microscopy, X-ray photoemission spectroscopy and electron energy-loss spectroscopy indicated that the Co element was incorporated into TiO2 to form the Ti1- x Co x O2 magnetic semiconductors. The obvious Kerr rotations in the samples were observed, and the relation between the Kerr rotation and Co concentration was discussed.

2007-01-15

24

Enhanced photocatalytic activity of TiO2 nano-structured thin film with a silver hierarchical configuration  

International Nuclear Information System (INIS)

TiO2 sol-gels with various Ag/TiO2 molar ratios from 0 to 0.9% were used to fabricate silver-modified nano-structured TiO2 thin films using a layer-by-layer dip-coating (LLDC) technique. This technique allows obtaining TiO2 nano-structured thin films with a silver hierarchical configuration. The coating of pure TiO2 sol-gel and Ag-modified sol-gel was marked as T and A, respectively. According to the coating order and the nature of the TiO2 sol-gel, four types of the TiO2 thin films were constructed, and marked as AT (bottom layer was Ag modified, surface layer was pure TiO2), TA (bottom layer was pure TiO2, surface layer was Ag modified), TT (pure TiO2 thin film) and AA (TiO2 thin film was uniformly Ag modified). These thin films were characterized by means of linear sweep voltammetry (LSV), X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy and transient photocurrent (Iph). LSV confirmed the existence of Ag0 state in the TiO2 thin film. SEM and XRD experiments indicated that the sizes of the TiO2 nanoparticles of the resulting films were in the order of TT > AT > TA > AA, suggesting the gradient Ag distribution in the films. The SEM and XRD results also confirmed that Ag had an inhibition effect on the size growth of anatase nanoparticles. Photocatalytic activities of the resulting thin films were also evaluated in the photocatalytic degradation process of methyl orange. The preliminary results demonstrated the sequence of the photocatalytic activity of the resulting films was AT > TA > AA > TT. This suggested that the silver hierarchical configuration can be used to improve the photocatalytic activity of TiO2 thin film.

2008-01-15

25

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

International Nuclear Information System (INIS)

[en] 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)

2013-01-01

26

Fabrication of TiO2 thin film memristor device using electrohydrodynamic inkjet printing  

International Nuclear Information System (INIS)

[en] 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

27

Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.  

Science.gov (United States)

TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples. PMID:22859033

Yang, Chang-Hu; Ma, Zhong-Quan

2012-08-01

28

Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.  

UK PubMed Central (United Kingdom)

TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples.

Yang CH; Ma ZQ

2012-08-01

29

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

UK PubMed Central (United Kingdom)

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.

Meng J; Liang J; Ou X; Ding Y; Liang G

2008-03-01

30

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

31

Optimization of growth parameters of TiO2 thin films using a slow positron beam  

International Nuclear Information System (INIS)

TiO2 thin films grown on fused silica were investigated using positron Doppler broadening spectroscopy at the slow-positron-beam SPONSOR [1] at the Helmholtz-Zentrum Dresden-Rossendorf. Effects of changes in different parameters like temperature or oxygen flow during film deposition on positron sensitive parameters have been investigated and first results will be presented.

2013-06-10

32

Optimization of growth parameters of TiO2 thin films using a slow positron beam  

Science.gov (United States)

TiO2 thin films grown on fused silica were investigated using positron Doppler broadening spectroscopy at the slow-positron-beam SPONSOR [1] at the Helmholtz-Zentrum Dresden-Rossendorf. Effects of changes in different parameters like temperature or oxygen flow during film deposition on positron sensitive parameters have been investigated and first results will be presented.

Butterling, M.; Anwand, W.; Cornelius, S.; Potzger, K.; Smekhova, A.; Vinnichenko, M.; Wagner, A.

2013-06-01

33

Photocatalytic activity of dc magnetron sputter deposited amorphous TiO2 thin films  

International Nuclear Information System (INIS)

For photocatalytic thin film applications TiO2 is one of the most important materials. The most studied TiO2 crystal phase is anatase, though also rutile and brookite show good photoactivity. Usually anatase or a mixture of rutile and anatase is applied for powder or thin film catalysts. It has been claimed that amorphous films do not exhibit any or only a very low photocatalytic activity. We have deposited amorphous thin films by dc magnetron sputtering from sub-stoichiometric TiO2-x targets. The coatings are transparent and show a photocatalytic activity half of that of a thin layer of spin-coated reference photocatalyst powder. Annealing the thin films to yield anatase crystallization more than doubles their photocatalytic activity. At the same film thickness these thin films show the same activity as a commercially available photocatalytic coating. The dependence of the photocatalytic activity on deposition parameters like gas pressure and sputter power is discussed. A decrease in film density, as deduced from the refractive index and the microstructure, resulted in an increase in photocatalytic activity. Film thickness has a marked influence on the photocatalytic activity, showing a strong increase up to 300-400 nm, followed by a much shallower slope.

2007-10-31

34

The structural and electrical properties of TiO2 thin films prepared by thermal oxidation  

International Nuclear Information System (INIS)

Thin films of TiO2 were grown on n-type Si substrate by thermal oxidation of Ti films deposited by dc sputtering. The phase purity of TiO2 was confirmed by Raman spectroscopy, and secondary ion mass spectroscopy was used to analyze the interfacial and chemical composition of the TiO2 thin films. Metal-oxide-semiconductor capacitors with Al as the top electrode were fabricated to study the electrical properties of the TiO2 films. The current conduction mechanisms in thermally grown TiO2 films were observed to follow the space charge-limited current mechanism followed by a Schottky emission process both at and above room temperature. Three orders of magnitude of reduction in current density were observed for thermally grown samples while measured the I-V characteristics at 77 K and Fowler-Nordheim (F-N) tunneling was found to be a dominant conduction mechanism at higher biasing voltages

2008-10-01

35

Influence of terbium on structure and luminescence of nanocrystalline TiO2 thin films  

Science.gov (United States)

In this work analysis of the structural and optical properties of TiO2 thin films doped with terbium has been described. Samples were prepared by a high energy reactive magnetron sputtering process under low pressure of oxygen plasma. X-ray diffraction results have shown that different TiO2 crystal forms have been produced, depending on the amount of Tb dopant. The undoped matrix had rutile structure with crystallites with a size of 8.7 nm, while incorporation of 0.4 at. % of Tb into the film during the sputtering process resulted in anatase structure with bigger crystallites (11.7 nm). Increasing the amount of terbium up to 2 at. % and 2.6 at. % gave rutile structure with crystallites with a size of 6.6 nm for both films. However, Raman spectroscopy has revealed that in the case of TiO2:(2 at. % Tb), except for the rutile form, the presence of fine-crystalline anatase was observed. Moreover, the lack of Raman peaks shift attests to the lack of stress in the titania lattice of all of the TiO2:Tb films. This fact indicates localization of Tb3+ ions on the surface of TiO2 nanocrystals. In the case of optical investigation, results have shown that doping with terbium has a significant influence on the properties of TiO2, but it does not decrease the high transparency of the matrix. The observed changes of the transmission characteristics were produced only due to modification of the TiO2:Tb structure. Photoluminescence measurements have shown that emission of light from TiO2:Tb films occurs when the amount of terbium is 2.6 at. %. Based on the obtained results a scheme of direct energy transfer from titanium dioxide matrix (with rutile structure) to Tb3+ ions has been proposed.

Wojcieszak, Damian; Kaczmarek, Danuta; Domaradzki, Jaroslaw; Lukowiak, Anna; Strek, Wieslaw

2013-02-01

36

Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores poliméricos Nanostructured TiO2 thin films by polymeric precursor method  

Directory of Open Access Journals (Sweden)

Full Text Available This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful attainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm.

Daniel Grando Stroppa; Tania Regina Giraldi; Edson Roberto Leite; José Arana Varela; Elson Longo

2008-01-01

37

Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores poliméricos/ Nanostructured TiO2 thin films by polymeric precursor method  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful at (more) tainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm.

Stroppa, Daniel Grando; Giraldi, Tania Regina; Leite, Edson Roberto; Varela, José Arana; Longo, Elson

2008-01-01

38

TiO2 thin films prepared by sol - gel method  

International Nuclear Information System (INIS)

[en] There is a growing awareness that titania (TiO2) and TiO2-based oxide systems are the most promising candidates for the development of photoelectrodes for photoelectrochemical cell (PEC) for solar-hydrogen production. The PEC is equipped with a single photoelectrode (photoanode) and cathode, both of which are immersed in an aqueous electrolyte. In this work we present a sol-gel method to prepare TiO2 thin films on ITO using tetraisopropoxides of titanium, acetylacetone, 1-butanol and Tween 80 as surfactant. The films were deposited on ITO coated glass slides by spray pyrolysis. UV-VIS spectra and fluorescence measurements were made for the solutions and films. X-ray diffraction was used for structural investigations and the morphology of the film was studied by Scanning Electron Microscopy.

2009-08-01

39

Nano structured TiO2 thin films by polymeric precursor method  

International Nuclear Information System (INIS)

This work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and NMR were applied for precursor's characterization and AFM, XRD and ellipsometry for thin films evaluation. Results showed successful attainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m2/g and monolayers thickness within 20 and 128 nm. (author)

2008-01-01

40

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

Directory of Open Access Journals (Sweden)

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.

Agnieszka Borkowska; Jaroslaw Domaradzki; Danuta Kaczmarek; Damian Wojcieszak

2007-01-01

 
 
 
 
41

Characterization of TiO2 Thin Films on Glass Substrate Growth Using DC Sputtering Technique  

International Nuclear Information System (INIS)

It has been fabricated and characterization a TiO2 thin films deposited on glass substrate using DC sputtering technique. Fabrication of TiO2 thin films were carried out at electrode voltage 4 kV, sputtering current 5 mA, vacuum pressure 5 x 10-4 torr, deposition time 150 minutes, and temperature of the substrate were varied from 150 -350 oC, while as a gas sputter was argon. The results was tested their micro structure using SEM, and crystal structure using XRD and found that the crystal structure of TiO2 powder before deposited on glass substrate was rutile and anatase with orientation (110) and (200) for anatase and (100) and (111) rutile structure. While the crystal structure which deposited at temperature 150 oC and deposition time 2.5 hours was anatase with orientation (001) and (200). (author)

2002-06-27

42

Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

43

Optical Spectra of Graded Nanostructured TiO2 Chiral Thin Films  

CERN Multimedia

The rigorous coupled wave analysis method (RCWA) is applied to the graded chiral TiO2 thin films in axial and non-axial excited states using the Bruggeman homogenization formalism. The dependence of the filtering frequency and polarization selectivity as a function of different structural parameters, are investigated. A good agreement with experimental results reported by other researchers is achieved.

Babaei, F; Savaloni, H; 10.1016/j.optcom.2010.03.005

2010-01-01

44

Growth of Sc-Doped TiO2 Thin Film by RF Magnetron Sputtering  

Science.gov (United States)

Sc-doped TiO2 (Ti1-xScxO2-?) thin film on Al2O3 substrate were prepared by RF magnetron sputtering using ceramics targets. The Ti1-xScxO2-? thin films deposited at room temperature were crystallized by postannealing at 800 °C for 1 h in O2 atmosphere. The thin films exhibited the single phase of rutile at x=0, the single phase of anatase at x=0.01 and mixed phases of rutile and anatase at x=0.03, and 0.05. The postannealed thin films were very smooth surface. In the absorption spectra, the fundamental absorption edge of Ti0.99Sc0.01O2-? thin film with anatase phase shifts to lower wavelength side than those of x=0, 0.03, and 0.05. The small Sc doping for TiO2 thin film contributes to the changes of band gap, lattice constant and crystal structure. The existence of acceptor-doped TiO2 may realize practical application of a wide gap semiconductor diode in blue-light region or fuel cell, which used oxide material.

Tomiyama, Kazuya; Kobayashi, Yusuke; Tsuda, Mitsuru; Higuchi, Tohru

2011-06-01

45

Magnetic and structural study of Cu-doped TiO2 thin films  

CERN Document Server

Transparent pure and Cu-doped (2.5, 5 and 10 at. %) anatase TiO2 thin films were grown by pulsed laser deposition technique on LaAlO3 substrates. The samples were structurally characterized by X-ray absorption spectroscopy and X-ray diffraction. The magnetic properties were measured using a SQUID. All films have a FM-like behaviour. In the case of the Cu-doped samples, the magnetic cycles are almost independent of the Cu concentration. Cu atoms are forming CuO and/or substituting Ti in TiO2. The thermal treatment in air promotes the CuO segregation. Since CuO is antiferromagnetic, the magnetic signals present in the films could be assigned to this Cu substitutionally replacing cations in TiO2.

Torres, C E R; Cabrera, A F; Errico, L A; Navarro, A M M; Renter'ia, M; S'anchez, F H; Duhalde, S

2007-01-01

46

The Photocatalytic and Antibacterial Activity of Cu-Doped TiO2 Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available Thin films of TiO2 and TiO2 doped with Cu were prepared by sol-gel method. The prepared films were calcined at the temperature of 400 °C for 2 h with the heating rate of 10 °C/min. Physical properties as well as crystal compositions of the fabricated films were characterized by XRD, EDX SEM and AFM techniques. The results show that all samples have thickness range from 0.25 to 1.0 um. The film surfaces are typically uniform and dense with TiO2 nanoparticles. The photocatalytic activities of the thin films were also tested via the degradation of methylene blue (MB) solution under UV irradiation. Finally, antibacterial activity efficiency was evaluated by the inactivation of E.coli. It was observed that higher Cu concentration gives better photocatalytic activity. With the highest dopant concentration investigated in this experiment (TiO2-1.0Cu condition) the films show photocatalytic of 70 % and antibacterial activity of 100 %.

Weerachai SANGCHAY; Lek SIKONG; Kalayanee KOOPTARNOND

2013-01-01

47

TiO2 thin films prepared by PLD for photocatalytic applications  

International Nuclear Information System (INIS)

[en] Photocatalytic titanium oxide (TiO2) thin films are synthesized by the Nd:YAG pulsed laser deposition (PLD) technique. The influence of laser repetition rate and substrate temperature on the crystalline structure is investigated by X-ray diffraction (XRD) measurement. Films deposited at a substrate temperature of 150 deg. C exhibit the anatase form, regardless of the repetition frequency. In films deposited at 300 deg. C, however, when the repetition rate is increased the crystal form changes from rutile to anatase. The change in crystal form is probably caused by a drop in the surface temperature of the growing film. The effect is very sensitive to repetition rate, which changes the deposition rate. The results suggest that control of the laser-pulse repetition rate in PLD is a very important factor for obtaining highly efficient photocatalytic TiO2 thin films

2002-09-30

48

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

UK PubMed Central (United Kingdom)

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.

Ogorevc JŠ; Tratar-Pirc E; Matoh L; Peter B

2012-06-01

49

Hydrogen gas sensors based on nanocrystalline TiO2 thin films  

Science.gov (United States)

Titanium dioxide thin films are extensively studied for applications in solid state gas sensor devices. Their gas sensing properties are strongly dependent on deposition technique, annealing temperature, film thickness and consequent properties like crystalline structure, grain size or amount of defects and impurities. In this work we report the gas sensing properties of TiO2 thin films prepared by reactive magnetron sputtering technique and subsequently annealed at temperatures 600°C and 900°C. The films were exposed to different concentrations of H2 gas up to 10 000 ppm. Their sensitivity to gas at various operating temperatures, ranging from 250°C to 450°C, was obtained by measuring their resistance.

Haidry, Azhar Ali; Schlosser, Peter; Durina, Pavol; Mikula, Marian; Tomasek, Milan; Plecenik, Tomas; Roch, Tomaš; Pidik, Andrej; Stefecka, Miloslav; Noskovic, Jaroslav; Zahoran, Miroslav; Kus, Peter; Plecenik, Andrej

2011-10-01

50

Preparation of the nano structured TiO2 thin film with dip-coating method  

International Nuclear Information System (INIS)

In this investigation, nano structured TiO2 thin films have been prepared through the Dip-coating method. The deposition solution was obtained through the hydrolysis of titanium iso-propoxide under the different range of ph. The transmission of films as an optical parameter investigated with spectrophotometer. Also the Fourier transform Infrared spectra have been used for determination of the structural phase of sample.

2006-01-01

51

Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications  

Directory of Open Access Journals (Sweden)

Full Text Available 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 Force Microscopy (AFM). The optical waveguiding properties of TiO2 films were investigated for both annealing temperature using m-lines spectroscopy. The refractive indices and the film thickness were determined from the measured effective indices. The results show that the synthesized planar waveguides are multimodes and demonstrate low propagation losses of 0.5 and 0.8 dB/cm for annealing temperature 350 and 500 °C, respectively.

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

2013-01-01

52

Characterization of reactive sputtered TiO2 thin films for gas sensor applications  

International Nuclear Information System (INIS)

The technology for preparing and characterisation of titanium dioxide (TiO2) thin films with properties appropriate for usage as gas sensors are discussed. For preparing the samples the methods of reactive radio frequency (RF) and direct current (DC) magnetron sputtering were used. The composition and microstructure of the films were studied by XPS, EPMA, XRD and Raman spectroscopy and the surface of the films was observed by high resolution SEM. Thorough profile analyses on the structure changes were performed by XPS. Interactions with the substrate and changes between the different modifications of the crystal structure also were investigated. For measuring the thickness and to identify the refractive indices of the films laser ellipsometry was used. The research was focused on the sensing behaviour of the sputtered TiO2 thin films. Films of various thickness were deposited on quartz resonators and the quartz crystal microbalance (QCM) method was used. This enables highly sensitive gas sensor capable of detecting changes in the molecular range to be constructed. Prototype QCM sensors with TiO2 sensitive films made in our laboratory, showed good sensitivity to ammonia at room temperature, and are currently being tested for sensitivity to other gasses.

2010-11-01

53

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

UK PubMed Central (United Kingdom)

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.

Jiang M; Li QS; Wang JN; Jin Z; Sui Q; Ma Y; Shi J; Zhang F; Jia L; Yao WG; Dong WF

2013-02-01

54

Influence of nanocrystalline structure and composition on hardness of thin films based on TiO2  

Science.gov (United States)

In this work, the influence of Tb-doping on structure, and especially hardness of nanocrystalline TiO2 thin films, has been described. Thin films were formed by a high-energy reactive magnetron sputtering process in a pure oxygen atmosphere. Undoped TiO2-matrix and TiO2:Tb (2 at. % and 2.6 at. %) thin films, had rutile structure with crystallite sizes below 10 nm. The high-energy process produces nanocrystalline, homogenous films with a dense and close packed structure, that were confirmed by X-ray diffraction patterns and micrographs from a scanning electron microscope. Investigation of thin film hardness was performed with the aid of a nanoindentation technique. Results of measurements have shown that the hardness of all manufactured nanocrystalline films is above 10 GPa. In the case of undoped TiO2 matrix, the highest hardness value was obtained (14.3 GPa), while doping with terbium results in hardness decreasing down to 12.7 GPa and 10.8 GPa for TiO2:(2 at. % Tb) and TiO2:(2.6 at. % Tb) thin films, respectively. Incorporation of terbium into TiO2-matrix also allows modification of the elastic properties of the films.

Kaczmarek, Danuta; Wojcieszak, Damian; Domaradzki, Jaroslaw; Prociow, Eugeniusz; Placido, Frank; Lapp, Steffen; Dylewicz, Rafal

2011-04-01

55

Photocatalysis of Thin Films of TiO2 on Al2O3 Substrates  

Science.gov (United States)

Titanium dioxide (TiO2) has grown to be one of the most promising photocatalysts in recent years because of extensive applications in renewable and clean energy. The rise in demand for these new energies has driven an increase in research on metal oxides and their properties. Our interest in growing the rutile structure of TiO2 stems from its lower excitation energy (3.0 eV) when compared to anatase (3.2 eV), which indicates it has better activity in the visible portion of the spectrum. It has been shown that sapphire (Al2O3) substrates are conducive to epitaxial rutile growth. In this study, we measured the photocatalytic activity of thin films of TiO2 on r-Al2O3 (1 -1 0 2) substrates. We used PLD and MBE to grow the films, which were characterized using XPS and AFM. Photoactivity was measured via the decomposition of methyl orange on the film's surface using a UV/VIS spectrophotometer. The decomposition of this organic compound is driven by oxidation-reduction reactions on the surface of the TiO2 film. From this, we calculated the charge carrier diffusion length and compared it to that of anatase.

Turbay, David; Luttrell, Timothy; Batzill, Matthias

2013-03-01

56

TiO2 thin films using organic liquid materials prepared by Hot-Wire CVD method  

International Nuclear Information System (INIS)

TiO2 thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO2 films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO2 crystallites

2008-01-15

57

Nano-scaled photocatalytic TiO2 thin films prepared by magnetron sputtering  

International Nuclear Information System (INIS)

Reactive r.f. magnetron sputtering was used as a PVD method for the deposition of photocatalytic TiO2 transparent films on glass substrate. X-ray diffraction, scanning electron microscopy and the measurement of the photocatalytic activity by the decomposition of methylene blue were applied for the film characterisation. The TiO2 films with the anatase structure and a variable film thickness ranging from 70 to 950 m were deposited on stationary substrate at two values of the total pressure with a goal to investigate their photocatalytic activity. It was found that the photocatalytic activity increases with increasing film thickness only if the films are prepared at higher sputtering pressures. Furthermore, 65 nm thick TiO2 films were deposited on rotating substrate and the relationship between the deposition parameters, such as the substrate temperature and the total pressure, the structure and the photocatalytic activity was studied. These thin films showed a very good photocatalytic activity when an appropriate substrate temperature (>100 deg. C) and/or total pressure (>1 Pa) are selected.

2003-06-02

58

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

UK PubMed Central (United Kingdom)

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.

Heuer WB; Xia HL; Abrahamsson M; Zhou Z; Ardo S; Narducci Sarjeant AA; Meyer GJ

2010-09-01

59

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

60

Nanocrystalline TiO2/ZnO thin films: fabrication and application to dye-sensitized solar cells.  

UK PubMed Central (United Kingdom)

Nanocrystalline TiO2 thin films composed of densely packed grains were deposited onto indium-doped tin oxide (ITO)-coated glass substrates at room temperature using a chemical bath deposition technique. A layer-by-layer (LbL) process was utilized to obtain a 1.418-microm-thick TiO2/ZnO structure. The TiO2 surface was super-hydrophilic, but its hydrophilicity decreased considerably after ZnO deposition. Other TiO2/ZnO films were studied to assess their suitability as photoelectrodes in dye-sensitized solar cells (DSSCs).

Mane RS; Lee WJ; Pathan HM; Han SH

2005-12-01

 
 
 
 
61

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)

2011-01-01

62

Photocatalytic Activity of TiO2 Thin Films Obtained by the Sputtering RF in Wastewater  

Science.gov (United States)

The photocatalytic activity of TiO2 thin films in wastewater, under an UV irradiation, is studied. The films were prepared on corning glass substrates by the sputtering RF technique. We present evidence on the photocatalytic degradation, carried out by advanced oxidation processes (AOPs) in domestic wastewater pretreated with UASB (upflow anaerobic sludge blanket) reactors. TiO2 films were illuminated with ultraviolet light during a time of 4 hours (? 264 nm). We could see the effect of degraded operation in the absorbance measurement using UV-VIS spectrophotometry. The results show an increased rate of degradation of the wastewater by 30% compared to the values reflected biologically treated wastewater by anaerobic reactors.

Cardona Bedoya, Jairo Armando; Asmed Sanchez Velandia, Wilmer; Iban Delgado Rosero, Miguel; Florido Cuellar, Alex Enrique; Zelaya Angel, Orlando; Mendoza Alvarez, Julio G.

2011-03-01

63

Microanalysis of Pd and V-doped TiO2 thin films prepared by sputtering  

International Nuclear Information System (INIS)

Thin films of TiO2 doped with vanadium and palladium, prepared by the magnetron sputtering method, were studied by means of X-ray diffraction (XRD), Scanning Electron Microscopy with Energy Disperse Spectrometer (SEM-EDS) and Atomic Force Microscopy (AFM). Investigations have brought important information about microstructure due to dopant incorporation in the TiO2 host lattice. Directly after deposition thin films were XRD-amorphous and SEM investigations did not reveal details on the microstructure. Analysis of the topography of prepared thin films required application of Atomic Force Microscope. The AFM images show that as-deposited sample was dense with grain sizes varied in the range of 5.5 nm-10 nm, that indicated high quality nanocrystalline behavior. Additional annealing results in the formation of three phases in the thin film, e.g. (Ti,V)O2 - solid solution, PdO and metallic inclusions of Pd. SEM-EDS system allowed analysis of the elemental composition, especially the V one, which lines have not been evidenced in the XRD diffraction pattern. EDS maps show homogenous distribution of elements Ti, O, V, Pd in prepared thin films.

2007-06-04

64

Properties of TiO2/LaxTi1-xOy/TiO2 Stacked Thin Films  

Science.gov (United States)

Electrical properties of TiO2/LaxTi1-xOy (x=0.51, y=1.73)/TiO2 stacked thin films were investigated in comparison with those of a composite LaxTi1-xOy (LTO) film. The band gap values of LTO and TiO2 were determined to be 3.65 and 3.10 eV, respectively. The conduction band offset values for LTO/Pt and TiO2/Pt systems were found to be 1.95 and 0.75 eV, respectively. Although the dielectric constant of the single-layer LTO film decreased to 19 with decreasing the physical thickness to less than 9 nm, the dielectric constant of the TiO2/LTO/TiO2 stacked film with a TiO2 thickness of 1 nm maintained a constant value of 25.5 even with decreasing the physical thickness. The TiO2/LTO/TiO2 stacked film with a 1-nm-thick TiO2 layer showed 10% smaller equivalent oxide thickness (EOT) than the single-layer LTO film at 1 V for a leakage current of 10-8 A/cm2. The stacked film also showed 1× 10-3 lower dielectric loss tangent than the single-layer LTO film with the same EOT.

Hara, Hikaru; Yamato, Masaki; Kikkawa, Takamaro

2009-10-01

65

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; Akbar Eshaghi; Mahmoud Pakshir

2013-01-01

66

Enhanced photocatalytic activity of silver nanoparticles modified TiO2 thin films prepared by RF magnetron sputtering  

International Nuclear Information System (INIS)

[en] Ag-TiO2 nanostructured thin films with silver volume fraction of 0-40% were prepared by RF magnetron sputtering. The microstructure, surface topography, and optical properties of the films were characterized by X-ray diffractometer, transmission electron microscope, and ultraviolet-visible spectrophotometer. Photocatalytic activity of the films was evaluated by light-induced degradation of methyl orange (C14H14N3NaO3S) solution using a high pressure mercury lamp as lamp-house. The relation of photocatalytic activity and silver content was studied in detail. It is found that silver content influences microstructure of TiO2 thin films, and silver in the films is metallic Ag (Ag0). Photocatalytic activity of the films increases with increasing silver content up to 5 vol.% Ag and then decreases to values significantly still bigger than that of pure TiO2 thin films. Silver nanoparticles significantly enhance the photocatalytic activity of TiO2 films. The better separation between electrons and holes on silver modified TiO2 thin films surface allowed more efficiency for the oxidation and reduction reactions. The enhanced photocatalytic activity was mainly attributed to the decrease of energy gap of the films and the increase of oxygen anion radicals O2- and reactive center of surface Ti3+ on silver modified TiO2 thin films surface.

2009-12-15

67

A short literature survey on iron and cobalt ion doped TiO2 thin films and photocatalytic activity of these films against fungi  

International Nuclear Information System (INIS)

Highlights: ? Co or Fe doped TiO2 thin films were prepared by sol–gel method. ? We obtained lower Eg values for Fe-doped and Co-TiO2 thin films. ? Doping greatly affected the size and shape of the TiO2 nanoparticles. ? Photocatalytic killing effect of the doped TiO2 thin films on C. albicans and A. niger was significantly higher than undoped TiO2 thin film for short exposure periods. - Abstract: In this study, a short recent literature survey which concentrated on the usage of Fe3+ or Co2+ ion doped TiO2 thin films and suspensions were summarized. Additionally, a sol–gel method was used for preparation of the 2% Co or Fe doped TiO2 thin films. The surface of the prepared materials was characterised using scanning-electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis and band gap of the films were calculated from the transmission measurements that were taken over the range of 190 and 1100 nm. The Eg value was 3.40 eV for the pure TiO2, 3.00 eV for the Fe-doped TiO2 film and 3.25 eV for Co-TiO2 thin film. Iron or cobalt doping at lower concentration produce more uniformed particles and doping greatly affected the size and shape of the TiO2 nanoparticles. Photocatalytic killing effect of the 2% Co doped TiO2 thin film on Candida albicans was significantly higher than Fe doped TiO2 thin film for short and long exposure periods. Doped thin films were more effective on Aspergillus niger for short exposure periods.

68

Structural and optical properties of rutile and anatase TiO2 thin films: Effects of Co doping  

International Nuclear Information System (INIS)

[en] Pure and Co-doped TiO2 thin films were grown on Al2O3(0001) substrates by reactive radio-frequency magnetron sputtering and sol-gel method. Rutile TiO2 films oriented to the a-axis of the tetragonal structure were obtained by the sputtering while polycrystalline anatase TiO2 films were obtained by the sol-gel method. Post-annealing of the deposited films in the air at 800 deg. C resulted in an improvement of the crystalline quality for both the rutile and anatase films. For Co doping up to 15 at.% the sputter-grown films maintained the a-axis-oriented rutile structure with the same lattice constant as in the pure TiO2 film. Optical properties of the rutile and anatase TiO2 films were measured by spectroscopic ellipsometry at room temperature in the 1.5-5 eV photon energy region. Band-gap energies of the rutile and anatase TiO2 films are determined to be 3.25 and 3.75 eV, respectively. The band-gap energy of the Co-doped rutile TiO2 films is found to increase with increasing Co composition

2005-07-22

69

Gasochromic switching of Ta and Pd-doped nanocrystalline TiO2 thin films.  

Science.gov (United States)

In this work TiO2:(Ta, Pd) thin films with gasochromic properties have been described. Thin films were prepared by reactive magnetron sputtering process using mosaic Ti-Ta-Pd target. The amounts of dopants were 2.54 at.% and 12.36 at.% of Ta and Pd, respectively. The results of optical measurements performed at presence of ethanol and additional heating of the sample up to 350 degrees C have shown an abrupt change of transmission level from 80% down to 10% in VIS and in IR range. The gasochromic change was very fast. Moreover, rapid cooling (down to room temperature) in an air ambient results in stable thin film coloration. The reverse effect (bleaching) was obtained after annealing at 500 degrees C in an ambient air. PMID:22400253

Domaradzki, J; Wojcieszak, D; Prociow, E; Kaczmarek, D; Winiarski, A; Szade, J

2011-10-01

70

Gasochromic switching of Ta and Pd-doped nanocrystalline TiO2 thin films.  

UK PubMed Central (United Kingdom)

In this work TiO2:(Ta, Pd) thin films with gasochromic properties have been described. Thin films were prepared by reactive magnetron sputtering process using mosaic Ti-Ta-Pd target. The amounts of dopants were 2.54 at.% and 12.36 at.% of Ta and Pd, respectively. The results of optical measurements performed at presence of ethanol and additional heating of the sample up to 350 degrees C have shown an abrupt change of transmission level from 80% down to 10% in VIS and in IR range. The gasochromic change was very fast. Moreover, rapid cooling (down to room temperature) in an air ambient results in stable thin film coloration. The reverse effect (bleaching) was obtained after annealing at 500 degrees C in an ambient air.

Domaradzki J; Wojcieszak D; Prociow E; Kaczmarek D; Winiarski A; Szade J

2011-10-01

71

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.

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

2001-01-01

72

Effect of Annealing on Structure, Morphology, Electrical and Optical Properties of Nanocrystalline TiO2 Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available 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 rutile phase structure and homogeneous surface. The study also reveals that the rms value of thin film roughness increases from 7 to 19 nm. HRTEM image of TiO2 thin film (annealed at 700 °C) shows that a grain of about 50 - 60 nm in size is really aggregate of many small crystallites of around 10 - 15 nm. Electron diffraction pattern shows that the TiO2 films exhibited tetragonal structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine with an average grain size of about 50 - 60 nm. The optical band gap slightly decreases from 3.26 - 3.24 eV and the dc electrical conductivity was found in the range of 10-6 to 10-5(?·cm)-1 when the annealing temperature is changed from 400 to 700 °C. It is observed that TiO2 thin film annealed at 700 °C after deposition provide a smooth and flat texture suited for optoelectronic applications.

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

2011-01-01

73

Photocatalytic decomposition of diclofenac potassium using silver-modified TiO2 thin films  

International Nuclear Information System (INIS)

[en] The effects of silver insertion on the TiO2 photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO2 thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO2 anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mgC W-1 when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material

2008-07-31

74

Remarkable enantioselectivity of molecularly imprinted TiO2 nano-thin films  

International Nuclear Information System (INIS)

TiO2 nano-thin films with imprinted (R)- and (S)-enantiomers of propranolol, 1,1'-bi-naphthol, and 2-(4-isobutylphenyl)-propionic acid were fabricated on quartz plates by spin-coating their solutions with Ti(O-nBu)4 in a toluene-ethanol mixture (1:1, v/v). After template removal, the imprinted films showed better binding for original templates than to the corresponding enantiomers. The assessment of template incorporation, template removal, and re-binding was conducted through UV-vis measurements. Significant enhancement of enantioselectivity was achieved by optimization of the film thickness and by heat-treatment of the imprinted films. After subtraction of non-specific binding, the optimized films provided chiral recognition with the enantioselectivity of almost 100% for (R)-propranolol and 95% for (S)-propranolol.

2011-05-23

75

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

Science.gov (United States)

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.

Thakurdesai, Madhavi; Kanjilal, D.; Bhattacharyya, Varsha

2012-08-01

76

Influences of surface capping with electrostatically self-assembled PEI on the photoresponse of a TiO2 thin film.  

UK PubMed Central (United Kingdom)

The photoresponse of a TiO2 thin film was significantly improved due to the decrease in the Schottky barrier height between Au and TiO2 via the formation of interface dipoles, which was caused by electrostatically self-assembled PEI on the surface of the TiO2 film.

Gu X; Meng F; Liu G; Zhang H; Zhou J; Ruan S

2013-07-01

77

The preparation and characterization of photocatalytically active TiO2 thin films and nanoparticles using Successive-Ionic-Layer-Adsorption-and-Reaction  

International Nuclear Information System (INIS)

Photocatalytically active TiO2 thin-films were deposited on silicon wafers using the Successive-Ionic-Layer-Adsorption-and-Reaction technique and subsequent hydrothermal and/or furnace annealing. Atomic-force-microscopy images and X-ray diffraction measurements of the TiO2 films obtained under various annealing conditions show how changes of the micro-scale surface structure depend on the post-SILAR treatment. The hydrogen evolution over various TiO2 films was measured. Hydrothermally treated TiO2 films show a higher photocatalytic activity and a much better mechanical stability compared to furnace-annealed films. The optical transmittance of TiO2 thin films on glass substrates was also studied. A red shift was observed with increasing film thickness. TiO2 nanoparticles (?10 nm) that were peeled off from the TiO2 films were investigated using high-resolution-transmission-electron-microscopy.

2006-12-05

78

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.

79

Synthesis of highly active thin film based on TiO2 nanomaterial for self-cleaning application.  

UK PubMed Central (United Kingdom)

Highly active self-cleaning surfaces were prepared from hydrothermally treated TiO2 nanomaterials for different times (0, 12, 24 and 36 h) under acidic condition. TiO2 thin films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). TiO2 thin film (hydrothermal 24h) exhibited hybrid morphology from accumulated plates, clusters, rods and spheres. The photo self-cleaning activity in term of quantitative determination of the active oxidative species (OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results show that, the highly active thin film is the hydrothermally treated for 24 h at 200 °C. The structural, morphology and photoactivity properties of nano-TiO2 thin films make it promising surfaces for self-cleaning application. Mineralization of commercial textile dye (Remazol Red RB-133, RR) from highly active TiO2 thin film surface was applied. Moreover, the durability of this nano-TiO2 thin film (hydrothermal 24h) was studied.

Saif M; El-Molla SA; Aboul-Fotouh SM; Hafez H; Ibrahim MM; Abdel-Mottaleb MS; Ismail LF

2013-08-01

80

Preparation and characterization of transparent hydrophilic photocatalytic TiO2/SiO2 thin films on polycarbonate.  

UK PubMed Central (United Kingdom)

Transparent hydrophilic photocatalytic TiO2 coatings have been widely applied to endow the surfaces self-cleaning properties. A mixed metal oxide (TiO2/SiO2) can enhance the photocatalytic performance improving the ability of surface adsorption and increasing the amount of hydroxyl surface groups. The present work introduces a systematic study concerning the effect of the SiO2 addition to TiO2 films on the wettability, the photocatalytic activity, the adhesion strength, and the mechanical stability of the films. Transparent hydrophilic photocatalytic TiO2/SiO2 thin films were used to coat the polycarbonate (PC) substrate which was precoated by an intermediate SiO2 layer. The TiO2/SiO2 thin film was prepared employing a bulk TiO2 powder (Sachtleben Hombikat UV 100) and different molar ratios of tetraethoxysilane in acidic ethanol. A dip-coating process was used to deposit the films onto the polycarbonate substrate. The films were characterized by UV/vis spectrophotometry, FTIR spectroscopy, ellipsometry, BET, AFM, XRD, and water contact angle measurements. The mechanical stability and the UV resistance were examined. The photocatalytic activity of the coated surface was calculated from the kinetic analysis of methylene blue photodegradation measurements and compared with the photocatalytic activity of Pilkington Activ sheet glass. The coated surfaces displayed considerable photocatalytic activity and superhydrophilicity after exposure to UV light. The addition of SiO2 results in an improvement of the photocatalytic activity of the TiO2 film reaching the highest value at molar ratio TiO2/SiO2 equal to 1:0.9. The prepared films exhibit a good stability against UV(A) irradiation.

Fateh R; Dillert R; Bahnemann D

2013-03-01

 
 
 
 
81

Electrochromic TiO2, ZrO2 and TiO2-ZrO2 thin films by dip-coating method  

International Nuclear Information System (INIS)

Sol-gel processing of TiO2, ZrO2 and mixed Ti/Zr oxide thin films has been studied as application of these coatings in electrochromic devices. Their structural transformations as a function of annealing temperatures were analyzed by XRD and FTIR techniques. Electrochromic behavior of the three kind materials was investigated by cyclic voltammetry and the basic electrochromic characteristics were determined.

2009-12-15

82

Photocatalytic Separate Evolution of Hydrogen and Oxygen over Highly Ordered Nanorods and Bulk TiO2 Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available Three types of photocatalytic TiO2 thin films with different structures, nanorods (NR-TiO2), mesoporous (MP-TiO2), and bulk structure (BK-TiO2), were prepared by evaporation induced self-assembling process or electron beam induced deposition method. The post-calcination treatment at 400oC was performed for all TiO2 thin films to induce their crystallinity. The TiO2 structure on the film properties were studied by material characterizations. The photoelectrochemical characteristics of the TiO2 films were investigated using a potentiostat. Under UV-light irradiation, a highest net photocurrent of 0.747 mA was observed for the NR-TiO2 thin film. To demonstrate the photoactivity of the prepared TiO2 thin films, water-splitting reactions were conducted. The yields of hydrogen and oxygen were 35.8 and 17.2 ?mole, respectively after 8 hr. of UV-light irradiation on NR-TiO2.

Chao-Wei Huang; Chi-Hung Liao; Jeffrey C. S. Wu

2013-01-01

83

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; Jong-Chang Woo; Chang-Il Kim

2012-01-01

84

The enhanced conductivity and stability of AZO thin films with a TiO2 buffer layer  

Science.gov (United States)

Aluminum doped zinc oxide (AZO) films were substitutes of the SnO2:F films on soda lime glass substrate in the amorphous thin-film solar cells due to good properties and low cost. In order to improve properties of AZO films, the TiO2 buffer layer had been introduced. AZO films with and without TiO2 buffer layer were deposited on soda lime glass substrates by r.f. magnetron sputtering. Subsequently, one group samples were annealed in vacuum (0.1 Pa) at 500 °C for 120 s using the RTA system, and the influence of TiO2 thickness on the properties of AZO films had been discussed. The XRD measurement results showed that all the films had a preferentially oriented (0 0 2) peak, and the intensity of (0 0 2) peak had been enhanced for the AZO films with TiO2 buffer layer. The resistivity of TiO2 (3.0 nm)/AZO double-layer film is 4.76×10-4 ? cm with the maximum figure merit of 1.92×10-2 ?-1, and the resistivity has a remarkable 28.7% decrease comparing with that of the single AZO film. The carrier scattering mechanism of TiO2 (3.0 nm)/AZO double-layer film had been described by Hall measurement in different temperatures. The average transmittance of all the films exceeded 92% in the visible spectrum. Another group samples were heat treated in the quartz tube in air atmosphere, and the effect of TiO2 thickness on thermal stability of AZO films had been discussed.

Yang, Tianlin; Song, Shumei; Li, Yanhui; Xin, Yanqing; Du, Guiqiang; Lv, Maoshui; Han, Shenghao

2012-12-01

85

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

UK PubMed Central (United Kingdom)

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.

Raut NC; Mathews T; Sundari ST; Sairam TN; Dash S; Tyagi AK

2009-09-01

86

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

87

Wettability conversion of colloidal TiO2 nanocrystal thin films with UV-switchable hydrophilicity.  

UK PubMed Central (United Kingdom)

Under pulsed laser UV irradiation, thin-film coatings made of close-packed TiO2 nanorods individually coated with surfactants can exhibit a temporary increase in their degree of surface hydroxylation without any apparent photocatalytic removal of the capping molecules. This mechanism provides a basis for achieving light-driven conversion from a highly hydrophobic to a highly hydrophilic, metastable state, followed by extremely slow recovery of the original conditions under dark ambient environment. A deeper insight into the wetting dynamics is gained by time-dependent water contact-angle and infrared spectroscopy monitoring of the film properties under different post-UV storage conditions. Our study reveals that, for reversible switchability between extreme wettability excursions and long-term repeatability of such changes to be achieved, specific modifications in the polar and nonpolar components of the TiO2 films need to be guaranteed along with preservation of the original geometric arrangement of the nanocrystal building blocks. The application of moderate vacuum is found to be an effective method for accelerating the post-UV hydrophilic-to-hydrophobic conversion, thereby enabling fast and cyclic hydrophilization/hydrophobicization alternation without any detrimental signs of significant fatigue.

Caputo G; Cingolani R; Cozzoli PD; Athanassiou A

2009-05-01

88

Control of conducting filaments in TiO2 films by a thin interfacial conducting oxide layer at the cathode  

Science.gov (United States)

The influences of the conducting oxide layer and phases of TiO2 on the electroforming behavior of TiO2 films on Ru were studied for unipolar resistive switching. The thin RuO2 layer makes the conducting filaments (CF) too strong due to a limited oxygen supply and accompanying high power consumption. When the oxygen supply was too high (TiO2 film on thick RuO2), CF formation was essentially disturbed and no switching occurs. The phase of TiO2 does not have any relevance to the resistance switching. Fluent and uniform switching was achieved by spatially confining the CF to a local area.

Keun Kim, Seong; Joon Choi, Byung; Jean Yoon, Kyung; Woo Yoo, Yeon; Seong Hwang, Cheol

2013-02-01

89

Room temperature ferromagnetism in Co-incorporated TiO2 thin films.  

Science.gov (United States)

Observation of room temperature ferromagnetism (RTFM) in nano-crystalline Co-incorporated titanium dioxide [Ti(1-x)Co(x)O2(x = 0.05)] thin films prepared by spray pyrolysis technique is reported. While only the anatase phase was detected in as-deposited 5 at.% Co-incorporated TiO2 film, a small amount of rutile phase developed following its vacuum annealing. Besides, no X-ray diffraction peak corresponding to cobalt metal could be detected in any of the two films. SQUID magnetometry of both pristine and Co-doped thin films at room temperature elucidated distinct ferromagnetic behavior in 5 at.% Co-incorporated as-deposited film with saturation moment M(s) approximately 5.6 emu/cm3 which got enhanced up to 11.8 emu/cm3 on subsequent vacuum annealing. From the zero field cooled magnetization measurement we confirmed the absence of Co-metal clusters. The electrical resistivity was found to be greater than 108 omega-cm for the films. Based on the magnetic and electrical measurements the origin of RTFM has been attributed to the bound magnetic polaron (BMP) model. PMID:21449467

Sharma, Sudesh; Chaudhary, Sujeet; Panwar, N; Kashyap, Subhash C; Pandya, D K

2011-03-01

90

Room temperature ferromagnetism in Co-incorporated TiO2 thin films.  

UK PubMed Central (United Kingdom)

Observation of room temperature ferromagnetism (RTFM) in nano-crystalline Co-incorporated titanium dioxide [Ti(1-x)Co(x)O2(x = 0.05)] thin films prepared by spray pyrolysis technique is reported. While only the anatase phase was detected in as-deposited 5 at.% Co-incorporated TiO2 film, a small amount of rutile phase developed following its vacuum annealing. Besides, no X-ray diffraction peak corresponding to cobalt metal could be detected in any of the two films. SQUID magnetometry of both pristine and Co-doped thin films at room temperature elucidated distinct ferromagnetic behavior in 5 at.% Co-incorporated as-deposited film with saturation moment M(s) approximately 5.6 emu/cm3 which got enhanced up to 11.8 emu/cm3 on subsequent vacuum annealing. From the zero field cooled magnetization measurement we confirmed the absence of Co-metal clusters. The electrical resistivity was found to be greater than 108 omega-cm for the films. Based on the magnetic and electrical measurements the origin of RTFM has been attributed to the bound magnetic polaron (BMP) model.

Sharma S; Chaudhary S; Panwar N; Kashyap SC; Pandya DK

2011-03-01

91

Uniform thin films of TiO2 nanoparticles deposited by matrix-assisted pulsed laser evaporation  

International Nuclear Information System (INIS)

We report morphological and optical properties of a colloidal TiO2 nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1 ?m in size was noticed. Form UV-vis transmission spectra, recorded in the 200-800 nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO2 nanoparticle thin films.

2007-05-30

92

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

Directory of Open Access Journals (Sweden)

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

93

Waveguiding Properties of Nano-Structured TiO2 Thin Films Synthesized by Sol-Gel Process  

Science.gov (United States)

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 structural, morphological and optical properties of the prepared films were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM). The optical and waveguiding properties of TiO2 films were investigated for both annealing temperatures using m-lines spectroscopy. The results show that our fabricated TiO2 waveguides are multimodes and demonstrate low propagation losses of 0.9 dB.cm-1.

Znaidi, L.; Touam, T.; Vrel, D.; Kunetsova, I. N.; Fischer, A.; Boudrioua, A.

2011-12-01

94

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye’s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

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

2007-01-01

95

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 (more) of deposits on the characteristics of the film. Using ultraviolet-visible spectroscopy, we observed a shift from the maximum absorption band at 545 nm for the dye?s ethanol solution to 595 nm for the film, indicating interaction of the cyanidin with the TiO2. The absorption spectra in the infrared region of the functionalized TiO2 particles showed bands characteristic of the oxide and indicated their interaction with the dye. Using profilometry and m-line techniques, we found that the films presented thicknesses in the order of 100 nm. A SEM analysis confirmed the high density of the films.

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

2007-12-01

96

Rutherford backscattering analysis of porous thin TiO2 films  

International Nuclear Information System (INIS)

[en] The additional energy spread due to sample porosity was implemented in the SIMNRA simulation code, version 6.60 and higher. Deviations of the path length and energy loss distributions from the ones expected from a Poisson distribution of the number of traversed pores are taken into account. These deviations are due to the interaction of pores at higher pore concentrations by overlap or blocking. The skewnesses of the energy distributions are approximated by two-piece normal distributions with identical first three moments. Propagation of porosity-induced energy spread in thick layers is taken into account. Calculated results are compared to experimental data obtained with thin TiO2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry.

2012-02-15

97

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

98

CdSe-sensitized TiO2 nanotube array film fabricated by ultrasonic-assisted electrochemical deposition and subsequently wrapped with TiO2 thin layer for the visible light photoelectrocatalysis  

International Nuclear Information System (INIS)

A composite structure, TiO2 nanotube array/CdSe nanoparticle/TiO2 layer, was fabricated by inserting CdSe nanoparticles into anodized TiO2 nanotube arrays via ultrasonic-assisted cyclic voltammetry electrochemical deposition and subsequently wrapped by a TiO2 thin layer via TiCl4 hydrolysis. The films were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy and UV–vis diffuse reflectance spectroscopy. For the film used as the photoanode, linear sweep voltammetry and transient photocurrent were investigated in a three-electrode system under visible light illumination. And the photocatalytic activity was evaluated by the oxidation of glucose in the supporting electrolyte at different potential bias under visible light illumination. The results showed that CdSe nanoparticles are prone to disperse into the nanotube arrays via cyclic voltammetry electrochemical deposition under ultrasonic condition. Increasing cyclic voltammetry cycle increases the loading of CdSe on the TiO2 nanotube arrays. The CdSe-sensitized TiO2 nanotube array films exhibit a wide-absorption response in the visible light region. The TiO2 nanotube array/CdSe/TiO2 film, prepared by ultrasonic-assisted electrochemical deposition with 50 cyclic voltammetry cycles and subsequently coating a TiO2 thin layer, exhibits better protection against photocorrosion of CdSe. The TiO2NTA/CdSe/TiO2 film possesses visible light photoelectrocatalytic activity on the degradation of glucose. - Highlights: ? CdSe is electrochemically deposited onto TiO2 nanotube arrays with ultrasonics. ? TiO2 thin layer overcoating on the arrays can protect CdSe from photocorrosion. ? TiO2 nanotube array/CdSe/TiO2 film possesses visible light photocatalytic activity.

2012-01-31

99

Structural and Electrical Properties of TiO2 Thin Film Derived from Sol-gel Method using Titanium (IV) Butoxide  

Directory of Open Access Journals (Sweden)

Full Text Available Fabrication of titanium dioxide (TiO2) thin film on microscope glass using sol-gel method has been studied intensively. The starting materials were titanium (IV) butoxide, ethanol, acetic acid, triton x-100, hydrochloric acid and deionized water. The materials were mixed together to form the sols. Then, the heat and ageing treatment was applied to form stable sols. The sols were then spin coated on the glass substrate to form the homogenous and transparent TiO2 thin film. The TiO2 thin film was coated at several layers using specific conditions. To evaluate the performance of thin film, the crystallinity of the thin film was determined by using the x-ray diffractometer  (XRD). The change on the surface morphology was observed using atomic force microscope (AFM). The electrical property of the thin film was determined by doing the current-voltage (I-V) analysis on the thin film. It has been successfully shown that the anatase crystalline phase was observed when the TiO2 thin film was heated at 500°C. The roughness and the crystalline phase of TiO2 thin film changed drastically with the growth conditions. Finally, the effect of film preparation to the film resistivity also showed a critical aspect where we should take into account during the preparation of TiO2 thin film.

Isrihetty Senain; Nafarizal Nayan; Hashim Saim

2010-01-01

100

Structural and Optical Characteristics of TiO2 Nanoparticles-Containing Mesoporous Silica (SBA-15) Thin Films  

International Nuclear Information System (INIS)

The thin films of ordered mesoporous silica (SBA-15) with nanometer-sized pores have been formed on silicon substrates. It was confirmed that the pores were hexagonally ordered as the stacking of rows of pores and silica walls in the direction normal to the substrate surface. From the results of X-ray reflectivity and diffraction the pore size and wall thickness were evaluated to be ?4.8 nm and ?2.1 nm, respectively. Furthermore, titanium dioxide nanoparticles were successfully synthesized in the pores of SBA-15 thin film. X-ray photoelectron spectroscopy of SBA-15 thin film after TiO2 synthesis indicated that the nanoparticles in the pores were titanium dioxide which included a small amount of defects. The optical reflectance of TiO2-containing SBA-15 film decreased at wavelengths shorter than 350 nm as compared with that of SBA-15 film before the TiO2 synthesis, resulting in optical absorption by the TiO2 nanoparticles in the pores of SBA-15.

2011-09-19

 
 
 
 
101

Surface characterization of TiO2 thin films obtained by high-energy reactive magnetron sputtering  

International Nuclear Information System (INIS)

This paper presents the results of surface characterization of TiO2 thin films deposited on different substrates by the use of high-energy reactive magnetron sputtering. Structural investigations carried out by X-ray diffraction (XRD) and atomic force microscopy (AFM) have shown a strong influence of both the substrate type, and its placement in the deposition chamber (relative to the sputtering target), on the structural properties of the films. In all cases, there is evidence for pseudoepitaxial growth. XRD examination showed existence of TiO2-rutile phase with preferred (1 1 0) orientation and AFM measurements revealed nanocrystalline structure directly after deposition. X-ray photoelectron spectroscopy analysis showed that the TiO2 films have stoichiometric composition.

2008-05-15

102

TiO2 nanoparticle thin film deposition by matrix assisted pulsed laser evaporation for sensing applications  

International Nuclear Information System (INIS)

The MAPLE technique has been used for the deposition of nanostructured titania (TiO2) nanoparticles thin films to be used for gas sensors applications. An aqueous solution of TiO2 nanoparticles, synthesised by a novel chemical route, was frozen at liquid nitrogen temperature and irradiated with a pulsed ArF excimer laser in a vacuum chamber. A uniform distribution of TiO2 nanoparticles with an average size of about 10 nm was deposited on Si and interdigitated Al2O3 substrates as demonstrated by high resolution scanning electron microscopy-field emission gun inspection (SEM-FEG). Energy dispersive X-ray (EDX) analysis revealed the presence of only the titanium and oxygen signals and FTIR (Fourier transform infra-red) revealed the TiO2 characteristic composition and bond. A comparison with a spin coated thin film obtained from the same solution of TiO2 nanoparticles is reported. The sensing properties of the films deposited on interdigitated substrates were investigated, too.

2007-07-31

103

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.

1904-01-00

104

Cyclic voltammetry and contact angle measurement studies of the Mo(VI) ions doped TiO2 thin films  

International Nuclear Information System (INIS)

Undoped and Mo(VI) ions doped TiO2 thin films were prepared via sol-gel method on different substrates. The morphology and the crystalline structures of the thin films were studied by SEM and XRD. The UV light inducing hydrophilicity was improved by doping Mo(VI) ions. The influence of the dopant density on the photo-induced superhydrophilicity of the films was investigated using cyclic voltammetry. A new oxidation peak was observed at about 0.17 V when the TiO2 electrodes were irradiated by UV light for a certain time. The peak current increased with the irradiation time. To reach the same peak current, 0.75% Mo(VI) ions doped films required short time than the undoped film

2007-06-15

105

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

International Nuclear Information System (INIS)

[en] 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.

1115-01-00

106

Bipolar resistive switching properties of microcrystalline TiO2 thin films deposited by pulsed laser deposition  

International Nuclear Information System (INIS)

TiO2 thin films were deposited on ITO (indium-tin-oxide)-buffered glass by pulsed laser deposition. Bipolar resistive switching behaviors of Ag/microcrystalline TiO2/ITO stacked structures were systematically investigated. Dependence of switching voltage and band gap energy on deposition temperature were also analyzed. Results indicate that the reset voltages and band gap energy (Eg) vary from -0.9 V to -6.8 V and 3.26 eV to 3.18 eV respectively, while the TiO2 films were formed from 300 deg. C to 600 deg. C. These bipolar switching phenomena have been also discussed based on the Schottky barrier at the Ag/TiO2 interface structure

2009-02-15

107

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

Energy Technology Data Exchange (ETDEWEB)

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 doping. The narrowing distinction among the effects of different doping methods combined with increasing resistivity of the films with improving crystalline quality of TiO2 suggest that structural defects play a critical role in the doping process.

Jacimovic, J [EPFL, Lausanne, Switzerland; Gaal, R [Institute of Condensed Matter Physics, EPFL, Lausanne, Switzerland; Magrez, Arnaud [ORNL; Forro, Laszlo [ORNL; Regmi, Murari [Oak Ridge National Laboratory (ORNL); Eres, Gyula [ORNL

2013-01-01

108

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

International Nuclear Information System (INIS)

[en] 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

109

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

UK PubMed Central (United Kingdom)

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 J; Frandsen CJ; Noh K; Johnston GW; He G; Tang T; Jin S

2013-04-01

110

Formation of nano-hillocks by impact of swift heavy ions on thin films of TiO2  

International Nuclear Information System (INIS)

Amorphous thin films of TiO2 are irradiated by swift heavy ion (SHI) beam. Surface topography is studied by atomic force microscopy (AFM). Formation of nanosized oblate hillocks on the surface of irradiated films is investigated by AFM studies. After irradiation, amorphous to crystalline phase transition is observed in glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy studies. Photoluminescence (PL)-spectroscopy is carried out for optical characterization. Threshold value necessary for emergence of hillocks is estimated.

2008-05-30

111

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

112

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 V oc = 628 mV and a short circuit current I sc = 22.6 ?A, where the surface of the formed cell is 3.14 cm2.

Ghrairi, Najla; Bouaicha, Mongi

2012-07-01

113

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

UK PubMed Central (United Kingdom)

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.

Ghrairi N; Bouaicha M

2012-01-01

114

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

115

Optimization of PZT Thin Film Crystalline Orientation Through Optimization of TiO2/Pt Templates.  

Science.gov (United States)

Titanium dioxide (TiO2) seed/adhesion layers were produced by sputter depositing 15-45-nm thick Ti films on thermally grown silicon oxide (SiO2) using a range of deposition conditions including deposition time, cathode power, and argon (Ar) gas pressure g...

D. M. Potrepka G. R. Fox R. G. Polcawich

2011-01-01

116

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

117

Structural, optical and magnetic properties of a Mn thin film sandwiched between TiO2 films prepared by magnetron sputtering  

International Nuclear Information System (INIS)

Mn-TiO2 sandwich composite films were grown on glass and silicon substrates by alternately using radio frequency and direct current magnetron sputtering. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to characterize the surface structure of the Mn-TiO2 films. XPS analysis confirmed the presence of Mn and TiO2. Transmission spectra show that the absorption edge has a red shift with increase in the thickness of an Mn thin film between two TiO2 films, which originated from quantum confinement effect. The hysteresis loop shows that Mn-TiO2 sandwich film has ferromagnetic behavior, which has the saturation magnetization of 4.2 emu/g, remanent magnetic induction of 0.47 emu/g and coercivity of 377.6 Oe for the Mn thin film with the thickness of 33.6 nm between the two TiO2 films.

2002-01-01

118

Influence of thickness and air annealing on structural, morphological, compositional, electrical properties of sprayed TiO2 thin films  

Directory of Open Access Journals (Sweden)

Full Text Available TiO2 thin films were prepared by spray pyrolysis technique at a substrate temperature of 3500C under optimum conditions. Films have uniform thickness varying from 0.3–6 ?m and good adhesion to substrate. The films were characterized by XRD, SEM and EDAX measurements. XRD profile shows poly crystalline nature of films. As deposited films have anatase phase. Transformation from anatase to anatase–rutile mixed phase may be due to annealing at 4000C and thickness variation of films. The microstructural properties such as crystallite size, microstrain and dislocation density found to increase due to concentration of lattice imperfections and crystallization of amorphous TiO2 films. SEM micrographs exhibit spherical, square, flower shaped grains and grain boundary formation. EDAX analysis revealed the formation of stoichiometric TiO2 films. Electrical studies show that the films are of n-type nature and increase in resistivity is attributed to surface oxidation and formation of Ti2O3 structure, a perfect insulator.

R.SHASHIDHAR; L.C.S.MURTHY

2013-01-01

119

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

120

Thickness-dependent photocatalytic performance of nanocrystalline TiO2 thin films prepared by sol–gel spin coating  

Science.gov (United States)

TiO2 nanocrystalline thin films on soda lime glass have been prepared by sol–gel spin coating. The thin films were characterized for surface morphology, crystal structure, chemical composition, thickness, and transparency by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ellipsometry, and UV–vis spectrophotometry. The films prepared by titanium tetraisopropoxide (TTIP) as the precursor under pH of 3.5 ± 0.5 and with calcination temperature of 450 ?C for 3 h exhibited superior homogeneous aggregation, good optical transparency, superhydrophilicity, and reliable thickness. The effect of film thickness on the photocatalytic degradation of acid yellow 17 was investigated under UV irradiation. The photocatalytic activity was strongly correlated with the number of coatings and followed Langmuir-type kinetics. Under the same film thickness, TiO2 thin films prepared by 0.1 M TTIP exhibited more efficient photocatalytic activity than those prepared by 0.3 M TTIP. For thin films prepared by 0.1 M TTIP, the maximum specific photocatalytic activity occurred at 5 coatings with thickness of 93 ± 1 nm. A model was proposed to rationalize the dependence of the film thickness on the photocatalytic activity, which predicts the existence of an optimum film thickness.

Wu, Chung-Yi; Lee, Yuan-Ling; Lo, Yu-Shiu; Lin, Chen-Jui; Wu, Chien-Hou

2013-09-01

 
 
 
 
121

An unconventional route to high-efficiency dye-sensitized solar cells via embedding graphitic thin films into TiO2 nanoparticle photoanode.  

UK PubMed Central (United Kingdom)

Graphitic thin films embedded with highly dispersed titanium dioxide (TiO(2)) nanoparticles were incorporated for the first time into the conventional dye-sensitized solar cells (DSSCs), resulting in a remarkably improved cell efficiency due to its superior electron conductivity. Massively ordered arrays of TiO(2) dots embedded in carbon matrix were fabricated via UV-stabilization of polystyrene-block-poly(4-vinylpyridine) films containing TiO(2) precursors followed by direct carbonization. For dye-sensitized TiO(2) based solar cells containing carbon/TiO(2) thin layers at both sides of pristine TiO(2) layer, an increase of 62.3% [corrected] in overall power conversion efficiency was achieved compared with neat TiO(2)-based DSSCs. Such a remarkably improved cell efficiency was ascribed to the superior electron conductivity and extended electron lifetime elucidated by cyclic voltammetry and impedance spectroscopy.

Jang YH; Xin X; Byun M; Jang YJ; Lin Z; Kim DH

2012-01-01

122

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

123

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

Directory of Open Access Journals (Sweden)

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

2004-01-01

124

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

International Nuclear Information System (INIS)

[en] 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

125

Study of 44Ti grain boundary self-diffusion in thin nanocrystalline TiO2 films  

Energy Technology Data Exchange (ETDEWEB)

Titanium dioxide is known for its photo-catalytic properties and enhanced corrosion resistance in aqueous environments. Due to these properties TiO2 is very attractive material for light-induced self-cleaning glass, water-cleaning and producing hydrogen from water applications. Numerous works are dedicated to the diffusion of various dopants like niobium or chromium in TiO2 but so far, none studied the self-diffusion of titanium in nanocrystalline TiO2. The grain boundary self-diffusion in thin nanocrystalline TiO2 films is investigated. The oxide films are produced using a novel deposition method from metal-organic precursors at relatively low (400-500 C) temperatures. A relaxation annealing at 800 C was performed. The diffusion was measured in temperature interval between 200 C and 600 C by means of the radiotracer technique applying the 44Ti isotope and utilizing ion beam sputtering for sectioning. The diffusion was measured at different oxygen pressures. In addition, the microstructure and its possible evaluation during diffusion annealing was investigated using TEM. The results are discussed with respect of the relationship between grain boundary self-diffusion and the synthesis pathway, the oxygen pressure and resulting microstructure of the nanoscale functional oxide films.

Straumal, Petr [Institut fuer Materialphysik, Universitaet Muenster, D-48149 Muenster (Germany); National University of Science and Technology, MISIS, 119049 Moscow (Russian Federation); Divinski, Sergiy; Wilde, Gerhard [Institut fuer Materialphysik, Universitaet Muenster, D-48149 Muenster (Germany)

2011-07-01

126

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

Scientific Electronic Library Online (English)

Full Text Available 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) and Auger electron spectroscopy (AES). SEM analysis showed a porous film with irregular morphology (diameter (more) 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

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

2004-12-01

127

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

128

Preparation of TiO2/WO3 multilayer thin film by PLD method and its catalytic response to visible light  

International Nuclear Information System (INIS)

We report about multilayer TiO2/WO3 thin films deposited on silicon and quartz glass substrate by pulsed laser deposition (PLD) method. The multilayer film has higher photocatalytic activity than TiO2 film under visible light irradiation. The films were characterized using an atomic force microscope (AFM), X-ray diffraction method (XRD) and UV-VIS absorption spectrometry. Photocatalytic efficiency of TiO2 and TiO2/WO3 multilayer thin film was also evaluated by photodecomposition of methylene blue (MB) in aqueous solution. The portion of WO3 layers in the multilayer film is very sensitive to photocatalytic property. The multilayer film containing 5% WO3 layers in thickness showed the highest dye decomposition ratio.

2006-05-26

129

Influence of the growth parameters of TiO2 thin films deposited by the MOCVD method  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis of TiO2 thin films was carried out by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during growth on the final structural characteristics was studied. A combination of the following experimental parameters was studied: temperature of the organometallic bath, deposition time, and temperature and substrate type. The high influence of those parameters on the final thin film microstructure was analyzed by scanning electron microscopy with electron dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction.

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

2002-01-01

130

Influence of the growth parameters on TiO2 thin films deposited using the MOCVD method  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we report the synthesis of TiO2 thin films by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during the growth in the obtained structural characteristics was studied. Different temperatures of the organometallic bath, deposition time, temperature and type of the substrate were combined. Using Scanning Electron Microscopy associated to Electron Dispersive X-Ray Spectroscopy, Atomic Force Microscopy and X-ray Diffraction, the strong influence of these parameters in the thin films final microstructure was verified.

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

2002-01-01

131

Preparation of grass-like TiO2 nanostructure thin films: Effect of growth temperature  

Science.gov (United States)

TiO2 nanoparticles with various morphologies have been synthesized under various temperature conditions, namely 25, 50, 60 and 90 °C via a liquid phase deposition technique. The liquid phase deposition technique is an electroless deposition of TiO2 onto the substrate surface via a unique hydrolysis of titanium complexes in the presence of H3BO3. FESEM characterization on the samples showed that, under the temperature treatment, the nanostructures morphology transformed from grass-like to agglomerated spherical-like shape with the increased of the temperature. The XRD analysis performed on these samples show that all of the samples were anatase and unmodified with the change in the morphology. The optical absorption window of the TiO2 nanostructures films was also found to enlarge with the increasing of the growth temperature, resulting from the structure modification. Owing to its simplicity, the present technique may produce TiO2 nanoparticles with a variety of morphologies for use in photocatalyst and solar cell applications.

Umar, A. A.; Rahman, M. Y. A.; Saad, S. K. M.; Salleh, M. M.; Oyama, M.

2013-04-01

132

Excimer laser processing as a tool for photocatalytic design of sol-gel TiO2 thin films  

International Nuclear Information System (INIS)

Nanostructured sol-gel TiO2 thin films spin coated on silicate glass plates are subjected to excimer (KrF*) pulsed laser irradiation in order to tailor their structure and photocatalytic properties. The surface morphology of virgin and laser-processed films are followed applying electron optical imaging and atomic force microscopy. The evolution of the surface roughness and pore formation are shown to be accompanied by optical absorption edge shift to infrared wavelength range. Conventional X-ray diffraction analysis and high-resolution transmission electron imaging are applied in order to obtain information on the phase composition. Co-existence of amorphous and anatase TiO2 phases in nonirradiated sol-gel films is found. It is established that after laser processing the most intense XRD anatase peak is shifted to lower 2? range. The analysis of high-resolution transmission electron images of film profiles evidences for the laser induced phase transitions. Formation of rutile and brookite TiO2 accompanied by evolution of oxygen deficient TinO2n-1 phases are identified in the subsurface region. The contribution of laser processing for increasing the photocatalytic efficiency of laser-modified films toward the oxidation of methylene blue water solution is demonstrated. The results obtained reveal a novel-processing route for designing sol-gel titania films with improved photocatalytical activity.

2008-04-30

133

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

134

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

135

The structure and photocatalytic activity of TiO2 thin films deposited by dc magnetron sputtering  

Science.gov (United States)

This paper seeks to determine the optimal settings for the deposition parameters, for TiO2 thin film, prepared on non-alkali glass substrates, by direct current (dc) sputtering, using a ceramic TiO2 target in an argon gas environment. An orthogonal array, the signal-to-noise ratio and analysis of variance are used to analyze the effect of the deposition parameters. Using the Taguchi method for design of a robust experiment, the interactions between factors are also investigated. The main deposition parameters, such as dc power (W), sputtering pressure (Pa), substrate temperature (°C) and deposition time (min), were optimized, with reference to the structure and photocatalytic characteristics of TiO2. The results of this study show that substrate temperature and deposition time have the most significant effect on photocatalytic performance. For the optimal combination of deposition parameters, the (1 1 0) and (2 0 0) peaks of the rutile structure and the (2 0 0) peak of the anatase structure were observed, at 2? ˜ 27.4°, 39.2° and 48°, respectively. The experimental results illustrate that the Taguchi method allowed a suitable solution to the problem, with the minimum number of trials, compared to a full factorial design. The adhesion of the coatings was also measured and evaluated, via a scratch test. Superior wear behavior was observed, for the TiO2 film, because of the increased strength of the interface of micro-blasted tools.

Yang, W. J.; Hsu, C. Y.; Liu, Y. W.; Hsu, R. Q.; Lu, T. W.; Hu, C. C.

2012-12-01

136

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

137

Influences of the Pd doping on the visible light photocatalytic activities of InVO4-TiO2 thin films  

International Nuclear Information System (INIS)

Novel Pd/InVO4-TiO2 thin films with visible light photo activity were synthesized via a sol-gel method from the Pd and InVO2 co-doped TiO2 sol. The photocatalytic activities of Pd/InVO4-TiO2 thin films were investigated based on the oxidation 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 result reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photo 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. The photocatalytic mechanism of Pd/InVO4-TiO2 thin films is investigated in this paper

2006-07-15

138

Mechanical characterization of thin TiO2 films by means of microelectromechanical systems-based cantilevers  

International Nuclear Information System (INIS)

The measurement of mechanical parameters by means of microcantilever structures offers a reliable and accurate alternative to traditional methods, especially when dealing with thin films, which are extensively used in microfabrication technology and nanotechnology. In this work, microelectromechanical systems (MEMS)-based piezoresistive cantilevers were realized and used for the determination of Young's modulus and residual stress of thin titanium dioxide (TiO2) deposited by sputtering from a TiO2 target using a rf plasma discharge. Films were deposited at different thicknesses, ranging from a few to a hundred nanometers. Dedicated silicon microcantilevers were designed through an optimization of geometrical parameters with the development of analytical as well as numerical models. Young's modulus and residual stress of sputtered TiO2 films were assessed by using both mechanical characterization based on scanning profilometers and piezoresistive sensing elements integrated in the silicon cantilevers. Results of MEMS-based characterization were combined with the tribological and morphological properties measured by microscratch test and x-ray diffraction analysis.

2010-01-01

139

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

UK PubMed Central (United Kingdom)

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.

Xiao X; Miao L; Zhang M; Xu G; Shao J; Fan Z

2013-02-01

140

Effects of TiO2 Interlayers on the Optical Switching of VO2 Thin Films Grown by Sol-Gel Process  

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Full Text Available Thermochromic VO2 and VxW1-xO2 films were deposited on TiO2/mica substrates. The TiO2/mica substrates were fabricated via Sol-Gel process, and the hydrophilicity of the TiO2/mica substrate was improved under UV light irradiated. The V2O5 sol was deposited on the TiO2/mica substrate by the spin coating method, and then it was annealed. SEM and XRD analysis were applied to analyze the morphology, phases and microstructure of the films. FTIR was used to study the thermochromic properties. The results suggest that VO2/TiO2 grow preferentially along single orientation. VxW1-xO2/TiO2 composite film is impossible to fabricate single orientation films. TiO2 interlayers are favorable to compact the VO2 thin films and reduce the transition temperature. It will make the hysteresis width of VxW1-xO2/TiO2 composite film reduce to about 4¡?articularly.

ZHANG Yu-Bo, HUANG Wan-Xia, SONG Lin-Wei, YAN Jia-Zhen, SHI Qi-Wu, ZHANG Yang

2013-01-01

 
 
 
 
141

Ordered mesoporous thin films of rutile TiO2 nanocrystals mixed with amorphous Ta2O5.  

Science.gov (United States)

Ordered mesoporous thin films of composites of rutile TiO2 nanocrystals with amorphous Ta2O5 are fabricated by evaporation-induced self-assembly followed by subsequent heat treatment beyond 780 degrees C. Incorporation of selected amounts of Ta2O5 (20 mol %) in the mesoporous TiO2 film, together with the unique mesoporous structure itself, increased the onset of crystallization temperature which is high enough to ensure the crystallization of amorphous titania to rutile. The ordered mesoporous structure benefits from a block-copolymer template, which stabilizes the mesostructure of the amorphous mixed oxides before crystallization. The surface and in-depth composition analysis by X-ray photoelectron spectroscopy suggests a homogeneous intermixing of the two oxides in the thin film. A detailed X-ray absorption fine structure measurement on the composite film containing 20 mol % Ta2O5 and heated to 800 degrees C confirms the amorphous nature of the Ta2O5 phase. Photocatalytic activity evaluation suggests that the rutile nanocrystals in the synthesized ordered mesoporous thin film possess good ability to assist the photodegradation of rhodamine B in water under illumination by UV light. PMID:18383238

Wu, Jin-Ming; Antonietti, Markus; Gross, Silvia; Bauer, Matthias; Smarsly, Bernd M

2008-04-01

142

Ordered mesoporous thin films of rutile TiO2 nanocrystals mixed with amorphous Ta2O5.  

UK PubMed Central (United Kingdom)

Ordered mesoporous thin films of composites of rutile TiO2 nanocrystals with amorphous Ta2O5 are fabricated by evaporation-induced self-assembly followed by subsequent heat treatment beyond 780 degrees C. Incorporation of selected amounts of Ta2O5 (20 mol %) in the mesoporous TiO2 film, together with the unique mesoporous structure itself, increased the onset of crystallization temperature which is high enough to ensure the crystallization of amorphous titania to rutile. The ordered mesoporous structure benefits from a block-copolymer template, which stabilizes the mesostructure of the amorphous mixed oxides before crystallization. The surface and in-depth composition analysis by X-ray photoelectron spectroscopy suggests a homogeneous intermixing of the two oxides in the thin film. A detailed X-ray absorption fine structure measurement on the composite film containing 20 mol % Ta2O5 and heated to 800 degrees C confirms the amorphous nature of the Ta2O5 phase. Photocatalytic activity evaluation suggests that the rutile nanocrystals in the synthesized ordered mesoporous thin film possess good ability to assist the photodegradation of rhodamine B in water under illumination by UV light.

Wu JM; Antonietti M; Gross S; Bauer M; Smarsly BM

2008-04-01

143

TiO2--Ta2O5 composite thin films deposited by radio frequency ion-beam sputtering.  

UK PubMed Central (United Kingdom)

TiO2--Ta2O5 composite films were prepared by a radio frequency ion-beam sputtering deposition process, and the refractive indices and extinction coefficients of the composite films were found to be between those of the TiO2 and Ta2O5 films. The structure of the as-deposited films was amorphous, and the surface roughness was approximately 0.1 nm. The residual stress of the composite films was less than that of pure TiO2 film. The structure of the composite films after annealing was amorphous, with low surface roughness and slightly increased residual stress. The film containing 6.3% TiO2 displayed better properties than either the pure TiO2 or the pure Ta2O5 film.

Lee CC; Tang CJ

2006-12-01

144

TiO2--Ta2O5 composite thin films deposited by radio frequency ion-beam sputtering.  

Science.gov (United States)

TiO2--Ta2O5 composite films were prepared by a radio frequency ion-beam sputtering deposition process, and the refractive indices and extinction coefficients of the composite films were found to be between those of the TiO2 and Ta2O5 films. The structure of the as-deposited films was amorphous, and the surface roughness was approximately 0.1 nm. The residual stress of the composite films was less than that of pure TiO2 film. The structure of the composite films after annealing was amorphous, with low surface roughness and slightly increased residual stress. The film containing 6.3% TiO2 displayed better properties than either the pure TiO2 or the pure Ta2O5 film. PMID:17151751

Lee, Cheng-Chung; Tang, Chien-Jen

2006-12-20

145

TiO2 thin films self-assembled with a partly fluorinated surfactant template.  

UK PubMed Central (United Kingdom)

New TiO(2) films have been self-assembled on solid substrate by dip-coating using TiCl(4) as the titanium source and the partly fluorinated surfactant F(CF(2))(8)C(2)H(4)(OC(2)H(4))(9)OH as the liquid crystal template. By control over the dip-withdrawal speed, film thicknesses from a minimum of 43 nm were produced with rms roughnesses of 0.5-0.7 nm. The films were characterized by X-ray reflectivity, grazing incidence small-angle X-ray scattering, atomic force microscopy, contact angle measurements, and Raman spectroscopy. Their GI-SAXS patterns are characteristic of a 2-D hexagonal structure in which tubular rods of the fluorinated surfactant are packed hexagonally and aligned parallel to the substrate. Reflectivity and contact angle measurements of the as-prepared film indicate that a low-density hydrophilic TiO(2) surface presents to the air.

Henderson MJ; Zimny K; Blin JL; Delorme N; Bardeau JF; Gibaud A

2010-01-01

146

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

147

Enhanced Hydrophilic Property of TiO2 Thin Film Deposited on Glass Etched with O2 Plasma  

Directory of Open Access Journals (Sweden)

Full Text Available TiO2 films were deposited on glass substrates with and without O2 plasma etching by using the RF-magnetronsputtering method. We focused on the effect of surface structure on the photoinduced hydrophilic properties of TiO2films, fabricated on different surface conditions according to the presence or absence of the O2 plasma treatmenton glass substrates. The wettability and photoinduced hydrophilic properties of the TiO2 films were investigatedaccording to the changes in water contact angles under UV light irradiations with a very low intensity of 0.1 mW/cm2.The photoinduced hydrophilic properties on the TiO2 formed above the plasma treated glass were also superior tothose on the TiO2 formed above the bare glass. This enhanced TiO2 film has been used practically for self cleaning andanti-fogging glasses.

Sun Young Sohn; Sung Bo Seo; Dong Young Kim; Kang Bae; Hwa-Min Kim

2013-01-01

148

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

149

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

Directory of Open Access Journals (Sweden)

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

2010-01-01

150

Ligand Coordination and Spin Crossover in a Nickel Porphyrin Anchored to Mesoporous TiO2 Thin Films.  

UK PubMed Central (United Kingdom)

The coordination and spin equilibrium of a Ni(II) meso-tetra(4-carboxyphenyl)porphyrin compound, NiP, was quantified both in fluid solution and when anchored to mesoporous, nanocrystalline TiO2 thin films. This comparison provides insights into the relative rate constants for excited-state injection and ligand field population. In the presence of pyridine, the spectroscopic data were consistent with the presence of equilibrium concentrations of a 4-coordinate low-spin S = 0 ((1)A1g) Ni(II) compound and a high-spin S = 1 ((3)B1g) 6-coordinate compound. Temperature-dependent equilibrium constants were consistently smaller for the surface-anchored NiP/TiO2, as were the absolute values of ?H and ?S. In the presence of diethylamine (DEA), the ground-state 6-coordinate compound was absent, but evidence for it was present after pulsed light excitation of NiP. Arrhenius analysis of data, measured from -40 to -10 °C, revealed activation energies for ligand dissociation that were the same for the compound in fluid solution and anchored to TiO2, Ea = 6.6 kcal/mol, within experimental error. At higher temperatures, a significantly smaller activation energy of 3.5 kcal/mol was found for NiP(DEA)2/TiO2. A model is proposed wherein the TiO2 surface sterically hinders ligand coordination to NiP. The lack of excited-state electron transfer from Ni(II)P*/TiO2 indicates that internal conversion to ligand field states was at least 10 times greater than that of excited-state injection into TiO2.

Achey D; Meyer GJ

2013-08-01

151

Ligand Coordination and Spin Crossover in a Nickel Porphyrin Anchored to Mesoporous TiO2 Thin Films.  

Science.gov (United States)

The coordination and spin equilibrium of a Ni(II) meso-tetra(4-carboxyphenyl)porphyrin compound, NiP, was quantified both in fluid solution and when anchored to mesoporous, nanocrystalline TiO2 thin films. This comparison provides insights into the relative rate constants for excited-state injection and ligand field population. In the presence of pyridine, the spectroscopic data were consistent with the presence of equilibrium concentrations of a 4-coordinate low-spin S = 0 ((1)A1g) Ni(II) compound and a high-spin S = 1 ((3)B1g) 6-coordinate compound. Temperature-dependent equilibrium constants were consistently smaller for the surface-anchored NiP/TiO2, as were the absolute values of ?H and ?S. In the presence of diethylamine (DEA), the ground-state 6-coordinate compound was absent, but evidence for it was present after pulsed light excitation of NiP. Arrhenius analysis of data, measured from -40 to -10 °C, revealed activation energies for ligand dissociation that were the same for the compound in fluid solution and anchored to TiO2, Ea = 6.6 kcal/mol, within experimental error. At higher temperatures, a significantly smaller activation energy of 3.5 kcal/mol was found for NiP(DEA)2/TiO2. A model is proposed wherein the TiO2 surface sterically hinders ligand coordination to NiP. The lack of excited-state electron transfer from Ni(II)P*/TiO2 indicates that internal conversion to ligand field states was at least 10 times greater than that of excited-state injection into TiO2. PMID:23914901

Achey, Darren; Meyer, Gerald J

2013-08-05

152

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. T...

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

153

Gamma Radiation Monitoring Through Thin Film of ClAlPc Doped With TiO2  

International Nuclear Information System (INIS)

[en] Chloroaluminum phthalocyanine (ClAlPc) synthesized by adopting focused microwave synthesis approach was doped with nanocrystalline TiO2 (5% by weight) and developed into the thin film sandwiched device having ITO/ClAlPc:TiO2/Ag Schottky configuration by spin coating technique covering 1 cm2 as an active area. The so fabricated device having initial dark current of the order of 0.2 5 m A was exposed to variable dose of gamma radiation ranging from lcGy to 10 Gy at a dose rate of 1 Gy/hour. The experimental observation reveals the generation of localized traps leading to structural disorder within the solid material. Doping with TiO2 enhances the surface area of the film which in tern improves sensitivity of device to wider dose rage. Exposure of the device to variable dose of gamma radiation imparts decrease in forward bias current and capacitance characteristics with increase in radiation dose. Also, absorbance characteristics of the Al Pc: TiO2 was analyzed before and after exposure to radiation which reveals that absorbance decreases with radiation dose leading to decrease in optical band gap

2008-04-23

154

Structural investigations of TiO2:Tb thin films by X-ray diffraction and atomic force microscopy  

International Nuclear Information System (INIS)

In this work, structural investigations of TiO2 thin films doped with Tb at the amount of 0.4, 2 and 2.6 at.% have been outlined. Thin films were deposited on Si and SiO2 substrates by high energy reactive magnetron sputtering from mosaic Ti-Tb target. The influence of Tb dopant amount, post-annealing treatment and kind of applied substrate on microstructure has been discussed. Thin films were investigated by means of X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis revealed the existence of crystalline TiO2 in anatase and rutile forms, depending on Tb amount in examined samples. AFM images show that as-deposited samples with 0.4 at.% concentration of terbium (anatase structure) have bigger crystallites as compared to 2% and 2.6 at.% of Tb (rutile structure). The additional annealing at 1070 K results in a mixed anatase (77%) and rutile (23%) structure.

2008-05-15

155

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

156

Irradiation induced ferromagnetism at room temperature in TiO2 thin films: X-ray magnetic circular dichroism characterizations  

International Nuclear Information System (INIS)

We report on the room temperature ferromagnetism in the swift heavy ion (SHI) irradiated TiO2 thin films by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) experiments at the O K and Ti L3,2 absorption edges. The XAS/XMCD measurements provide direct evidence of magnetic polarization of the O 2p and Ti 3d orbitals. The unquenched orbital magnetic moment within the O 2p shell is ferromagnetically coupled to the neighboring Ti moments, which illustrates the intense hybridization of the O 2p and Ti 3d orbitals induced by SHI irradiation.

1770-01-00

157

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

Science.gov (United States)

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.

Mohanty, P.; Mishra, N. C.; Choudhary, R. J.; Banerjee, A.; Shripathi, T.; Lalla, N. P.; Annapoorni, S.; Rath, Chandana

2012-08-01

158

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

159

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

International Nuclear Information System (INIS)

[en] 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

160

Structural Study And Optical Properties Of TiO2 Thin Films Elaborated By Thermal Oxidation Of RF Magnetron Sputtered Ti Films  

Science.gov (United States)

We report on the effect of thickness on the structural and optical properties of TiO2 thin films obtained by direct exposure of Ti metal film to thermal oxidation. Ti thin films with thicknesses ranging from 87 nm to 484 nm were deposited onto glass substrate by RF magnetron sputtering. Thereafter, the as-deposited Ti films were annealed in air at temperature equal to 520 °C. The structural evolution and optical properties of obtained TiO2 films were studied by means of Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and UV-Visible spectroscopy. The films thicknesses were extracted from RBS spectra. From X-ray diffraction spectra, we can see that all the films present three TiO2 phases (anatase, rutile and Brookite). The anatase and rutile phases exhibit a strong preferred orientation along (004) and (210) planes respectively. The grain sizes, D (nm), did not change much with increasing thickness. The average value of (nm) was equal to 29 nm for anatase and 26 nm for rutile. The micrographs taken from SEM experiments indicate that the films present a dense micro structure with very small grains. Transmittance spectra show that all the films present a good transparency in the visible region. The dependence of transmittance, optical band gap and refractive index on the thickness of the films was also studied.

Guitoume, D.; Achour, S.; Guittoum, A.; Abaidia, S. E. H.

2008-09-01

 
 
 
 
161

TiO2(Fe3+) nanostructured thin films with antibacterial properties  

International Nuclear Information System (INIS)

TiO2-based nanostructured Fe3+-doped coatings have been prepared by the sol-gel method on glass substrates. The coatings were characterized by X-ray diffraction and spectroellipsometry methods. The influence of Fe3+ dopant concentration, number of coatings, and calcination temperature on the films structure was established. The antibacterial activity against E. coli, has been studied applying the so-called antibacterial-drop test. The bactericidal activity for the above bacteria cells was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The coatings exhibited a high antibacterial activity, which was enhanced with the increase of the temperature of thermal treatment and formation of anatase crystalline structure. The long thermal treatment results in rutile crystalline structure formation followed by the decrease in the antibacterial activity of the coating.

2003-06-02

162

Comparison of the temperature dependence of the mechanical dissipation in thin films of Ta2O5 and Ta2O5 doped with TiO2  

International Nuclear Information System (INIS)

Here we report the first results comparing the temperature dependence of the mechanical dissipation in thin films of Ta2O5 and Ta2O5 doped with TiO2, of a type suitable for use in the multilayer optical coatings for advanced gravitational wave detectors. The results indicate that doping Ta2O5 with TiO2 can significantly alter the distribution of activation energies associated with the low-temperature dissipation peak.

2009-08-07

163

Nanocrystalline anatase TiO2 thin films: preparation and crystallite size-dependent properties  

International Nuclear Information System (INIS)

Nanocrystalline anatase TiO2 films with crystallites of either of three different sizes (nominally 6, 12, and 20 nm) were deposited on various substrates (glass, sapphire, and silicon) using colloidal suspensions. These suspensions were painted onto the respective substrates, dried in air and then calcined at 720 K in air for 1 h; the resulting films have a whitish appearance and are several ?m thick. These films were thoroughly characterized with respect to their surface morphology, crystal structure, phase homogeneity, elemental composition, and the presence of impurities. X-ray diffraction (XRD) and cross-section transmission electron microscopy (TEM) data demonstrated that two of the films are solely composed of the anatase phase whereas in the third also the brookite phase of TiO2 might be present. The average crystallite size was derived from the width of the XRD diffraction peaks and was found to agree within ?5% with the nominal size. The elemental composition and the amount of impurities in the different films was investigated by secondary-ion mass spectrometry. Whereas the Ti/O concentration is constant throughout all films, the presence of contaminants is substrate-dependent: while in films deposited on silicon or sapphire the atomic fraction of impurities (most prominently Na and K) is in the range of ?10-4, for glass substrates an about 100 times higher level of those species is observed, probably the result of outdiffusion during the calcination step or during the reduction of the samples. A detailed study of the influence of the sample temperature T and the ambient oxygen pressure p(O2) on the DC electrical conductivity ? of the films was performed. For all films, a power-law dependence of ? on p(O2), ??p(O2)-n, was observed. The values of the exponent n were found to exhibit a distinct dependence both on the crystallite size and on the specimen temperature; furthermore, an influence due to the presence of doping species was noted. For nanocrystalline films on sapphire substrates and for T=470 K, n amounts to 1.31, 1.15 and 0.56 for the 6-, 12-, and 20-nm films, respectively. For reduced films, an exponential dependence of ? on T -1 was determined, yielding activation energies EA with values of 0.34, 0.38, and 0.51 eV for films with those crystallite sizes. Impedance spectroscopy was utilized to determine the frequency-dependent complex resistance of the various films. In all cases, a pure RC behavior was found: whereas the magnitude of R strongly depends on the crystallite size, the sample temperature and the ambient oxygen pressure, C exhibits little variations and falls in the range ?18 to ?25 pF. Using thermal desorption mass spectrometry, distinct desorption peaks for O2 species were observed which shift to higher temperature values with increasing heating rate. An activation energy for that desorption process of ?0.9 eV was obtained thereof for a 6-nm nanocrystalline film.

2005-01-24

164

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

165

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

166

Room temperature synthesis of nanocrystalline anatase sols and preparation of uniform nanostructured TiO2 thin films: optical and structural properties  

Science.gov (United States)

Transparent TiO2 thin films were deposited on soda-lime glass substrates via the sol-gel method using a nanocrystalline TiO2 sol solution prepared at room temperature employing the dip-coating method. The effects of pH on crystallinity, particle size and stability of the synthesized TiO2 sols were investigated, systematically. TiO2 thin films were thickened by means of a sequential dip-coating process. The TiO2 films were transparent and exhibited proper adherence. The effects of thickness and annealing temperature on the structural and optical properties of the thin films were evaluated. The prepared powder was crystalline without any thermal treatment. The crystallite size of the particles (anatase) was in the range 4.2-12.1 nm depending on the initial pH value. Although only the anatase phase was observed at room temperature and 400 °C, a further increase in annealing temperature up to 700 °C resulted in the formation of the rutile phase. Even at high annealing temperatures, fairly smooth and homogeneous surfaces with no cracks and pores were observed. It was demonstrated that the films were transparent in the visible region with characteristic absorption in the UV region. Band gap of the as-deposited film was estimated to be 3.34 eV and was found to decrease with increasing annealing temperature.

Hosseingholi, M.; Pazouki, M.; Hosseinnia, A.; Aboutalebi, S. H.

2011-02-01

167

Spectroscopic study of the photofixation of SO2 on anatase TiO2 thin films and their oleophobic properties.  

Science.gov (United States)

Photoinduced SO(2) fixation on anatase TiO(2) films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO(2) films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO(2) gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO(2) exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO(2) films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO(2). The oxidation state of sulfur successively changed from S(4+) for SO(2) adsorbed on crystalline TiO(2) films at room temperature without irradiation to S(6+) for films exposed to SO(2) at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photoinduced surface reaction products formed on the TiO(2) surfaces. It is shown that band gap excitation of TiO(2) results in photoinduced oxidation of SO(2), which at elevated temperatures become coordinated to the TiO(2) lattice through interactions with O vacancies and form sulfite and sulfate surface species. These species makes the surface acidic, which is manifested in nondetectable adherence of stearic acid to the modified surface. The modified films show good chemical stability as evidenced by sonication and repeated recycling of the films. The results suggest a new method to functionalize wide band gap oxide surfaces by means of photoinduced reactions in reactive gases at elevated substrate temperatures. In the case of anatase TiO(2) in reactive SO(2) gas, we here show that such functionalization yields surfaces with excellent oleophobic properties, as probed by adhesion of stearic acid. PMID:22204641

Topalian, Z; Niklasson, G A; Granqvist, C G; Österlund, L

2012-01-26

168

Spectroscopic study of the photofixation of SO2 on anatase TiO2 thin films and their oleophobic properties.  

UK PubMed Central (United Kingdom)

Photoinduced SO(2) fixation on anatase TiO(2) films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO(2) films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO(2) gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO(2) exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO(2) films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO(2). The oxidation state of sulfur successively changed from S(4+) for SO(2) adsorbed on crystalline TiO(2) films at room temperature without irradiation to S(6+) for films exposed to SO(2) at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photoinduced surface reaction products formed on the TiO(2) surfaces. It is shown that band gap excitation of TiO(2) results in photoinduced oxidation of SO(2), which at elevated temperatures become coordinated to the TiO(2) lattice through interactions with O vacancies and form sulfite and sulfate surface species. These species makes the surface acidic, which is manifested in nondetectable adherence of stearic acid to the modified surface. The modified films show good chemical stability as evidenced by sonication and repeated recycling of the films. The results suggest a new method to functionalize wide band gap oxide surfaces by means of photoinduced reactions in reactive gases at elevated substrate temperatures. In the case of anatase TiO(2) in reactive SO(2) gas, we here show that such functionalization yields surfaces with excellent oleophobic properties, as probed by adhesion of stearic acid.

Topalian Z; Niklasson GA; Granqvist CG; Österlund L

2012-02-01

169

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

170

Correlation between microstructure and optical properties of nano-crystalline TiO2 thin films prepared by sol-gel dip coating  

International Nuclear Information System (INIS)

Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO2 thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO2 thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO2 thin films. The results show that the TiO2 thin films crystallize in anatase phase between 400 and 800 deg. C, and into the anatase-rutile phase at 1000 deg. C, and further into the rutile phase at 1200 deg. C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO2 thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 deg. C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

2010-11-15

171

Microstructure and bactericidal ability of photocatalytic TiO 2 thin films prepared by rf helicon magnetron sputtering  

Science.gov (United States)

The present study investigates the microstructure and bactericidal ability of polycrystalline and epitaxial TiO 2 thin films with anatase and rutile structure. Phase formation and the distortion of the lattice of the film compared with bulk are proved by TEM observation. HRTEM images assure the good crystal quality and compact structure of the films prepared by rf helicon magnetron sputtering. This obtained larger band gap due to the lattice deformation could contribute to the better photocatalytic effect of the anatase film. Bactericidal abilities evaluated by the photokilling E. Coli using film stick method under UV irradiation show the following result: Both single and polycrystal anatase films exhibit obvious bactericidal abilities while no distinguishing difference for them. On the other hand, no bactericidal ability is observed for rutile films in this work. The band gap value of rutile film is lower than the energy potential required to O 2/O 2- reductions according to the principle proposed by Fujishima et al. This resulted in the observed poor photocatalyst effect of rutile film.

Miao, Lei; Tanemura, Sakae; Kondo, Yoichi; Iwata, Misao; Toh, Shoichi; Kaneko, Kenji

2004-11-01

172

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

UK PubMed Central (United Kingdom)

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.

Sangchay W; Sikong L; Kooptarnond K

2013-02-01

173

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

174

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

175

Electrochemical-assisted photodegradation of dye on TiO2 thin films: investigation on the effect of operational parameters.  

UK PubMed Central (United Kingdom)

Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol(-1).

Zainal Z; Lee CY; Hussein MZ; Kassim A; Yusof NA

2005-02-01

176

Effects of the compliance current on the resistive switching behavior of TiO2 thin films  

Science.gov (United States)

Nanocrystalline TiO2 thin films were fabricated on Pt(111)/Ti/SiO2/Si substrates by the thermal oxidation of evaporated Ti films. Effects of the compliance current on the resistive switching behavior of the Pt/TiO2/Pt sandwich structures were studied in detail. The reset current increased when the compliance current increased from 10 mA to 20 mA. When the compliance current exceeded 20 mA, the switching behavior disappeared, which could be attributed to the change of the conducting behavior in the low-resistance state. A resistance change ratio of as high as 102 was obtained between the high-resistance state and the low-resistance state. The study of the effect of compliance current contributes to obtaining stable and reliable resistive switching behavior for nonvolatile memory applications.

Cao, X.; Li, X. M.; Gao, X. D.; Zhang, Y. W.; Liu, X. J.; Wang, Q.; Chen, L. D.

2009-12-01

177

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

International Nuclear Information System (INIS)

[en] 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

178

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

179

Silver enhanced TiO2 thin films: photocatalytic characterization using aqueous solutions of tris(hydroxymethyl)aminomethane.  

UK PubMed Central (United Kingdom)

The photocatalytic activity in aqueous solutions of TiO2 and Ag enhanced TiO2 sol-gel produced films was characterized using tris(hydroxymethyl)aminomethane (Tris) under black light (365 nm) and the observed differences in efficiency were further investigated by O2 adsorption studies using the same probe. Hydrogen abstracting species, such as hydroxyl radicals formed upon photocatalysis, are able to abstract hydrogen from Tris. This reaction leads to the formation of formaldehyde which was detected and quantified through a modified version of the Hantzsch reaction. It was found that the Ag enhanced TiO2 film increased the apparent quantum yield from 7% to 12%, partly as a result of a Schottky barrier formation at the metal-semiconductor interface and partly as the sensitizing effect of Ag nanoparticles extends the visible light absorption, which through electron transfer processes enable an efficient charge separation in the TiO2 by attracting acceptor species more efficiently than pure TiO2. The O2 adsorption studies in this paper showed that the Ag enhanced TiO2 film has a stronger adsorption affinity than pure TiO2 towards O2, which make the reduction of O2 more efficient with a subsequent enhanced electron-hole lifetime. It was also found that the Ag enhanced TiO2 film had a poorer adsorption affinity for Tris than the pure TiO2 film, which is a consequence of fewer available surface adsorption sites due to the Ag coverage at 64% which agrees well with the obtained adsorption equilibrium constants (KLH(TiO2) = 615 M(-1) and KLH(Ag-TiO2) = 320 M(-1)).

Diesen V; Dunnill CW; Osterberg E; Parkin IP; Jonsson M

2013-10-01

180

Photoactivity and hydrophilic property of SiO2 and SnO2 co-doped TiO2 nano-composite thin films  

Directory of Open Access Journals (Sweden)

Full Text Available SiO2 and SnO2 co-doped TiO2 nano-composite thin films were prepared by sol-gel method. The effects of film thicknessand amount of SiO2 and SnO2 co-doping into TiO2 nano-composite films on phase presence, crystallite size, photocatalyticreaction and hydrophilicity were investigated. Thickness of 3-coating layers (238 nm) seems to provide the highest photocatalyticactivity. The crystallinity of anatase phases, crystallite sizes and photocatalytic reactions of SiO2 and SnO2 co-dopedTiO2 films decrease with an increase in SiO2 content. It was found that more amount of SiO2 addition seems to inhibit graingrowth and the formation of anatase phase; especially when it was synthesized at temperature less than 600°C. The photocatalyticreaction seems to decrease with an increase in SiO2 doping when the concentrations of SnO2 in the composite films are fixed. It was apparent that 1SiO2/1SnO2/TiO2 composite film exhibits the highest photoactivity. Suitable amounts of SiO2and SnO2 doping into the TiO2 composite films tend to enhance the hydrophilic property of the films. It was also apparentthat the 3SiO2/3SnO2/TiO2, 5SiO2/5SnO2/TiO2 and 10SiO2/3SnO2/TiO2 composite films exhibit super hydrophilic characteristicsunder UV irradiation for 30 min.

Lek Sikong; Kalayanee Kooptarnond; Sutham Niyomwas

2010-01-01

 
 
 
 
181

Preillumination of TiO2 and Ta2O5 photoactive thin films as a tool to tailor the synthesis of composite materials.  

Science.gov (United States)

Illumination of TiO 2 thin films with UV light is known to induce the transformation of the surface of this material from partially hydrophobic into fully hydrophilic. The present work shows that this transformation is accompanied by other effects that may be used to control the synthesis of composite materials. For this purpose, TiO 2 and Ta 2O 5 transparent thin films with a columnar structure and open pores were prepared by electron evaporation at glancing angles. Transparent TiO 2 thin films with micropores (i.e., pores smaller than 2 nm) prepared by plasma enhanced chemical vapor deposition (PECVD) were also used. All these films became hydrophilic upon UV illumination. Rhodamine 6G and Rhodamine 800 dyes were irreversibly adsorbed within the columns of the TiO 2 and Ta 2O 5 thin films by immersion into a water solution of these molecules. Isolated and aggregated molecules of these two dyes were detected by visible absorption spectroscopy. The infiltration adsorption efficiency was directly correlated with the acidity of the medium, increasing at basic pHs as expected from simple considerations based on the concepts of the point of zero charge (PZC) in colloidal oxides. The infiltration experiments were repeated with columnar TiO 2 and Ta 2O 5 thin films that were subjected to preillumination with UV light. It was found that this treatment produced a modification in the type (isolated or aggregated) and amount of dye molecules incorporated into the pores. Moreover, the selective adsorption of a given dye in preilluminated areas of the films permitted the lithographic coloring of the films. Preillumination also controls the UV induced deposition of silver on the surface of the microporous TiO 2 thin films. It was found that the size distribution of the formed silver nanoparticles was dependent on the preillumination treatment and that a well-resolved surface plasmon resonance at around 500 nm was only monitored in the preilluminated films. A model is proposed to account for the effects induced by UV preillumination on the TiO 2 and Ta 2O 5 oxide surfaces. The possibilities of this type of light treatment for the tailored synthesis of nanocomposite thin films (i.e., dye-oxide, metal nanoparticles-oxide) are highlighted. PMID:18642860

Sánchez-Valencia, Juan R; Borrás, Ana; Barranco, Angel; Rico, Victor J; Espinós, Juan P; González-Elipe, Agustín R

2008-07-19

182

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

183

Relationship between Photocatalytic Activity, Hydrophilicity and Photoelectric Properties of TiO2 thin Films  

International Nuclear Information System (INIS)

[en] TiO2 thin films were prepared by PECVD technique from vapors of Titanium-IV iso-propoxide mixed with oxygen at different temperatures. The films were deposited on substrates with system of special platinum electrodes and on glass substrates. Photoconductivity and capacitance at different humidity, photocatalytic activity and photo-induced hydrophility under UV irradiation and surface morphology were evaluated on the films. The results revealed that the photoconductivity is influenced by humidity and is connected to the photocatalytic activity

2006-01-01

184

Influence of the growth parameters of TiO2 thin films deposited by the MOCVD method Influência dos parâmetros de crescimento de filmes finos de TiO2 depositados pelo método MOCVD  

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Full Text Available The synthesis of TiO2 thin films was carried out by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during growth on the final structural characteristics was studied. A combination of the following experimental parameters was studied: temperature of the organometallic bath, deposition time, and temperature and substrate type. The high influence of those parameters on the final thin film microstructure was analyzed by scanning electron microscopy with electron dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction.A síntese de filmes finos de TiO2 foi feita pelo método de deposição química do vapor de organometálicos (MOCVD). Foi estudada a influência de parâmetros de deposição usados durante o crescimento, nas características estruturais finais. Foi feita uma combinação de vários parâmetros experimentais: temperatura do banho do organometálico, tempo de deposição, e temperatura e tipo do substrato. A forte influência destes parâmetros na microestrutura final do filme foi analisada por microscopia eletrônica de varredura com espectroscopia de raios X dispersiva de elétrons, microscopia de força atômica e difração de raios X.

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

2002-01-01

185

Influence of the growth parameters on TiO2 thin films deposited using the MOCVD method/ Influência dos parâmetros de crescimento em filmes finos de TiO2 depositados pelo método MOCVD  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A síntese de filmes finos de TiO2 por meio do método MOCVD é descrita. Foi estudada a influência de parâmetros de deposição usados durante o crescimento nas características estruturais obtidas. Foram combinados diferentes temperaturas do banho organometálico, tempo de deposição, temperatura e tipo do substrato. A forte influência destes parâmetros na microestrutura final dos filmes foi estudada por meio de diferentes técnicas: microscopia eletrônica de varr (more) edura associada com espectroscopia eletrônica de dispersão de raios X, microscopia de força atômica e difração de raios X. Abstract in english In this work we report the synthesis of TiO2 thin films by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during the growth in the obtained structural characteristics was studied. Different temperatures of the organometallic bath, deposition time, temperature and type of the substrate were combined. Using Scanning Electron Microscopy associated to Electron Dispersive X-Ray Spectroscopy, Atomic Force Microscopy and (more) X-ray Diffraction, the strong influence of these parameters in the thin films final microstructure was verified.

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

2002-12-01

186

Influence of the growth parameters on TiO2 thin films deposited using the MOCVD method Influência dos parâmetros de crescimento em filmes finos de TiO2 depositados pelo método MOCVD  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we report the synthesis of TiO2 thin films by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during the growth in the obtained structural characteristics was studied. Different temperatures of the organometallic bath, deposition time, temperature and type of the substrate were combined. Using Scanning Electron Microscopy associated to Electron Dispersive X-Ray Spectroscopy, Atomic Force Microscopy and X-ray Diffraction, the strong influence of these parameters in the thin films final microstructure was verified.A síntese de filmes finos de TiO2 por meio do método MOCVD é descrita. Foi estudada a influência de parâmetros de deposição usados durante o crescimento nas características estruturais obtidas. Foram combinados diferentes temperaturas do banho organometálico, tempo de deposição, temperatura e tipo do substrato. A forte influência destes parâmetros na microestrutura final dos filmes foi estudada por meio de diferentes técnicas: microscopia eletrônica de varredura associada com espectroscopia eletrônica de dispersão de raios X, microscopia de força atômica e difração de raios X.

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

2002-01-01

187

Influence of the growth parameters of TiO2 thin films deposited by the MOCVD method/ Influência dos parâmetros de crescimento de filmes finos de TiO2 depositados pelo método MOCVD  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A síntese de filmes finos de TiO2 foi feita pelo método de deposição química do vapor de organometálicos (MOCVD). Foi estudada a influência de parâmetros de deposição usados durante o crescimento, nas características estruturais finais. Foi feita uma combinação de vários parâmetros experimentais: temperatura do banho do organometálico, tempo de deposição, e temperatura e tipo do substrato. A forte influência destes parâmetros na microestrutura final do (more) filme foi analisada por microscopia eletrônica de varredura com espectroscopia de raios X dispersiva de elétrons, microscopia de força atômica e difração de raios X. Abstract in english The synthesis of TiO2 thin films was carried out by the Organometallic Chemical Vapor Deposition (MOCVD) method. The influence of deposition parameters used during growth on the final structural characteristics was studied. A combination of the following experimental parameters was studied: temperature of the organometallic bath, deposition time, and temperature and substrate type. The high influence of those parameters on the final thin film microstructure was analyzed b (more) y scanning electron microscopy with electron dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction.

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

2002-03-01

188

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

Science.gov (United States)

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 °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.

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

2011-10-01

189

The effect of aeration and solar intensity power on photocatalytic degradation of textile industrial wastewater using TiO2 thin film  

International Nuclear Information System (INIS)

Solar photo catalytic degradation of the textile industry wastewater using TiO2 thin films was studied. This experiment was performed to investigate the effect of aeration and solar intensity power on decreasing of Chemical Oxygen Demand (COD). A serpentine flow photo catalytic reactor was developed for this purpose. TiO2 thin films photo catalyst supported on the stainless steel 304 substrates were prepared using sol-gel dip coating method. The results of thin films were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffractometer (XRD). XRD result showed that the prepared thin films gave the anatase crystallite formation whilst SEM demonstrated the macro pores were formed. Finally, the aeration and solar intensity power factors are considered to be responsible for the photo catalytic degradation. (Author)

2006-01-01

190

Study of the photocatalytic activity of nanocrystalline S, N-codoped TiO2 thin films and powders under visible and sun light irradiation  

Science.gov (United States)

Homogeneous and transparent sulfur and nitrogen (S, N)-codoped TiO2 nanocrystalline thin films were deposited on glass substrates by sol gel dip coating method using thiourea (Tu) as a source of sulfur and nitrogen. The surface structure of the films was modified by addition of different concentrations of polyethylene glycol (PEG) into the TiO2 sol. The equal powders of pure and modified TiO2 were also prepared to compare of their photocatalytic activity with films.The films and powders were characterized by different techniques like diffuse reflectance UV-Vis spectroscopy (DRS), X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX).DRS exhibited a shift in optical absorption wavelength to visible region and XRD analysis showed that only the anatase TiO2 formed in both of film and powder. The photocatalytic activity was evaluated by the degradation of methyl orange (MO) as a model. The modified TiO2 films and powders showed excellent visible-light photocatalytic ability for the degradation of MO under both irradiation of visible and sun light. So that, up to 96% MO can be decomposed in sun light only within 3 h in the presence of a modified TiO2 film consist of Tu/TiO2 molar ratio of 0.45 and 0.9 g PEG. On the other hand, MO solution was discolored completely under sun light in 75 min in the presence of the modified TiO2 powder.

Behpour, Mohsen; Atouf, Vajiheh

2012-06-01

191

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.

1770-01-00

192

Structural and electrical studies on sol-gel derived spun TiO2 thin films  

International Nuclear Information System (INIS)

[en] Titanium dioxide thin films were prepared by spin coating of sol precursor onto microscopic glass slides, silicon and indium tin oxide (ITO) coated glass substrates. Spin speed was varied between 1000 and 6000 rpm. From the morphological analysis, it is found that thin films spun with speed ??4000 rpm assume higher ordered structure than those spun at a speed higher than 4000 rpm. Conduction at low voltages is believed to be variable range hopping at temperatures Ta = 0.46 eV below the conduction band edge becomes dominant at temperatures higher than 220 K. At high field charge transport is due to trap-controlled space charge limited mechanism. Traps with a density Nt?1x1022 m-3 are thought to be situated at energy level Et 0.3 eV below the conduction band and are associated with film nonstoichiometry and interface states

2003-05-07

193

Influence of Eu dopant on optical properties of TiO2 thin films fabricated by low pressure hot target reactive sputtering  

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Full Text Available This work presents the influence of europium dopant on optical properties of TiO2:Eu3+ thin films fabricated by low pressure hot target reactive sputtering. Thin films were deposited from metallic Ti-Eu mosaic target on different substrates (i.e., monocrystalline silicon and SiO2). Selected samples were additionally annealed for 4 hours in an air ambient at 200 °C after deposition. Thin films were examined by means of scanning electron microscopy with energy disperse spectrometer (SEM-EDS), X-ray diffraction (XRD), optical transmission method and photoluminescence (PL). From SEM-EDS measurements total Eu concentration in fabricated thin films was determined. XRD analysis revealed the existence of crystalline TiO2 in the form of anatase and rutile in examined samples with smaller and larger amount of Eu dopant, respectively. Optical transmission method showed that doping with selected amount of Eu results in different shift of the fundamental absorption edge for prepared thin films. PL studies showed a red luminescence of TiO2:Eu3+ thin films. The intensity of luminescence increased with the annealing temperature and decreased with larger amount of europium.

Agnieszka BORKOWSKA; Jaroslaw DOMARADZKI; Danuta KACZMAREK

2007-01-01

194

Effect of nanostructured porous n+ GaAs substrates on the energy band gap of nanocrystalline TiO2 thin films analyzed by spectroscopic ellipsometry  

Science.gov (United States)

We present the optical properties of TiO2 deposited, by sol-gel method, on porous n+type GaAs substrates with different porosities and were thermally annealed at 600 °C for 15 min. The surface topography and density of grains packing at different samples were determined based on AFM images. AFM studies showed that the structure of the TiO2 thin film was nanocrystalline with grains size dependent on the etching time and ranging between 4 and 7 nm. The optical constants (n and k) of the films, as a function of etching time of GaAs substrate before and after deposition and content, were obtained using spectroscopic ellipsometer with rotating polarizer type in the ultraviolet-visible-near infrared (UV-vis-NIR) regions. The thickness of TiO2 thin films (top layer) and the mixed layer of TiO2 and porous GaAs (bottom layer) were determined by scanning electroscopic spectroscopy (SEM) and confirmed by spectroscopic ellipsometry using a modified Cauchy dispersion law for optical index calculation and through an optical model with double layers dispersion, we were able to determine the change of the optical properties of porous GaAs with integration effect of the TiO2 particle.

Abdellaoui, T.; Bennaceur, J.; Chtourou, R.

2010-11-01

195

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.

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

2013-01-01

196

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

Directory of Open Access Journals (Sweden)

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.

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

2013-01-01

197

Sol-gel preparation of TiO2-ZrO2 thin films supported on glass rings: Influence of phase composition on photocatalytic activity  

International Nuclear Information System (INIS)

In order to optimize the characteristics of TiO2-ZrO2 thin films supported on glass for the photocatalytic removal of VOCs, acidic sols of different composition (ZrO2, TiO2 and Ti-Zr mixed oxides) have been prepared using metal alkoxides as starting materials. The photoactive oxides were deposited on 'Raschig rings' of borosilicate glass using a dip-coating technique. The phase composition of the thin films was controlled during the sol preparation stage to produce either (1) Ti0.9Zr0.1O2 solid solutions, or (2) ZrO2/TiO2 binary metal oxides (10% and 20% molar content of Zr). The particle size of the different sols was measured by photon correlation spectroscopy, and the xerogels were characterized by XRD, N2 adsorption isotherms, and TG-DTA, so as to monitor the modifications induced by the thermal treatments. Raman spectroscopy was used to determine the crystalline structure of the supported TiO2-ZrO2 oxides, which in all cases corresponded to the anatase phase. The band gap of the thin films was estimated from the UV-vis spectra, and none of them differed significantly from that of unmodified TiO2. The photoactivity of the coated glass 'Raschig rings' was measured for the oxidation of acetone and methylcyclohexane vapors using, respectively, total recycle and single pass plug flow photoreactors. The results obtained indicate that, for the same Zr content, the photoactivity of the films containing binary metal oxides is slightly higher than that of the solid solution. In contrast, specific surface area seems to have little influence on the performance of the thin films

2006-04-28

198

Solar photocatalytic degradation of gaseous formaldehyde by sol-gel TiO2 thin film for enhancement of indoor air quality  

International Nuclear Information System (INIS)

[en] Solar photocatalytic degradation of formaldehyde in the gaseous phase has been investigated. The tested photoreactor is made of a borosilicate glass tube with the inner surface coated with a sol-gel TiO2 thin film. In a pseudo-first-order Langmuir-Hinshelwood (L-H) model, the maximum reaction rate constant obtained is 0.148 min-1 under an exposure to sunlight with solar UVA irradiance of 1.56 mW/cm2. The solar photolysis effect is found to be negligible. It is also found that the sol-gel TiO2 thin film has a lower apparent photonic efficiency of solar photocatalysis than a Degussa P25 TiO2 coating. However, for the photonic efficiency taking into account the absorbed and scattered photons only and, in other words, excluding the transmitted photons, the thin film has a higher value. Based on a total of 28 measured data, an empirical-correlation equation has been developed to express the reactant residue with respect to the solar UVA irradiance and exposure time. A reasonable agreement between the correlation and experimental data is obtained. The findings of this investigation can be applied to design optimization of a honeycomb photoreactor made up of TiO2-coated glass tubes or polygonal cells. (author)

2004-01-01

199

Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO2 thin film  

Science.gov (United States)

Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

Kang, Seung-Hee; Kumar, Ch. Kiran; Lee, Zonghoon; Kim, Kyung-Hyun; Huh, Chul; Kim, Eui-Tae

2008-11-01

200

Quantum-dot light-emitting diodes utilizing CdSe/ZnS nanocrystals embedded in TiO2 thin film  

International Nuclear Information System (INIS)

Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe/ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2/QDs/p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2/QDs/Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

2008-11-10

 
 
 
 
201

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

Directory of Open Access Journals (Sweden)

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; M. Kranjcec; O.T. Nahusko; O.M. Borets

2003-01-01

202

Studies of LPCVD and anodised TiO2 thin films and their photoelectrocatalytic photochemical properties for destruction of organic effluents  

International Nuclear Information System (INIS)

[en] TiO2 thin films prepared by CVD and anodisation methods and their applications for the photoelectrocatalytic and photocatalytic destruction of organic effluents are described in this thesis. The theoretical background of CVD, photoelectrocatalysis (PEC) and photocatalysis (PC) is introduced in Chapter 1. This chapter also contains an intensive literature review about TiO2 thin film preparation, mainly by CVD, and about PEC and PC destruction of organic effluents by TiO2 thin films. The experimental methods, which include CVD reactors, PEC cells and film characterisation and chemical analysis, are described in Chapter 2. The results for TiO2 films deposited by LPCVD on SnO2 coated glass using either TTIP or TTB precursors in the presence of O2, with or without water as a reagent, are discussed in Chapter 3 for a small CVD reactor and Chapter 4 for a large reactor. The effects of precursor, water and annealing on the crystal structure of the films have been investigated and compared. It was found that phase transition temperatures for changes from amorphous to anatase and anatase to rutile with TTIP were higher than those obtained with TTB. Water also had an effect by decreasing the temperature for depositing crystalline films. The other kind of TiO2 films prepared by anodisation of titanium mesh was studied and the results are presented in Chapter 5. PEC or PC destruction of MPA, RDX and 4-CP have been studied using TiO2 thin film anodes in small and large PEC reactors which are described in Chapter 6 and Chapter 7, respectively. PC destruction rates of organics are found to be improved significantly with an applied potential; i.e. by a PEC process. The effects of film properties, such as film crystallinity, thickness and film type on the PEC and PC efficiencies have been investigated. It was found that the different behaviour of films in PEC processes probably was due to surface effects rather than internal electric field differences. The extent of PEC and PC destruction of organics for CVD films was higher than for anodised films. The thesis concludes with an overall summary of the results and some suggestions for future work (Chapter 8). (author)

2001-01-01

203

Effects of oxygen partial pressure on packing density and laser damage threshold of TiO2 thin films  

International Nuclear Information System (INIS)

TiO2 films are deposited by electron beam evaporation as a function of oxygen partial pressure. The packing density, refractive index, and extinction coefficient all decrease with the increase of pressure, which also induces the change of the film's microstructure, such as the increase of voids and H2O concentration in the film. The laser-induced damage threshold (LIDT) of the film increases monotonically with the rise of pressure in this experiment. The porous structure and low nonstoichiometric defects absorption contribute to the film's high LIDT. The films prepared at the lowest and the highest pressure show nonstoichiometric and surface-defects-induced damage features, respectively.

2018-01-00

204

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.)

2009-01-01

205

On the optical properties of Ag+15 ion beam irradiated TiO2 and SnO2 thin films  

CERN Document Server

In this study, the effects of 200 MeV Ag+15 ion irradiation on the optical properties of TiO2 and SnO2 thin films prepared by RF magnetron sputtering technique were investigated. These films were characterized by the UV-vis spectroscopy and it was observed that with increase in irradiation fluence the transmittance for the TiO2 films systematically increases while that for SnO2 decreases. Absorption spectra of the irradiated samples showed a minor changes in indirect bandgap from 3.44 to 3.59 eV for TiO2 while that for SnO2 significant modifications in the direct bandgap from 3.92 to 3.6 eV were observed on increasing irradiation fluence. The observed modifications in the optical properties of both TiO2 and SnO2 systems with irradiation can be attributed to controlled structural disorder/defects in the system.

Thakur, Hardeep; Thakur, P; Sharma, K K; Singh, Abhinav Pratap; Kumar, Yogesh; Kumar, Ravi; Chae, Keun Hwa

2011-01-01

206

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

207

Photo-assisted electrochemical copper removal from cyanide solutions using porous TiO2 thin film photo-anodes  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english TiO2 porous films were prepared on ITO coated glass slides by the sol-gel dip-coating method assisted with Polyethylene glycol (PEG). The films were used as photo-anodes in the photo-assisted electrolytic removal of cuprous ions in cyanide media. These were characterized by SEM, UV-Visible spectroscopy and XRD. The PEG modified films were free of cracks and developed a porous structure after heat treatment at 500 ºC, due to the thermal decomposition of the structure asso (more) ciated PEG. It was demonstrated that the photo-assisted electrochemical reduction of copper is promoted by the use of modified TiO2 films as photo-anodes, thanks to the greater surface area given by the PEG decomposition. However, the film thickness was found to be a critical factor in the process, to such an extent that films composed of 5 layers were completely inefficient, meaning that despite the open porosity, multilayered films acted as a barrier within the photo-electrolytic process.

Ramírez-Santos, Álvaro A.; Acevedo-Peña, Próspero; Córdoba, Elcy M.

2013-01-01

208

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

209

Preparation of an orthodontic bracket coated with an nitrogen-doped TiO(2-x)N(y) thin film and examination of its antimicrobial performance.  

UK PubMed Central (United Kingdom)

A bracket coated with a nitrogen-doped (N-doped) TiO(2-x)N(y) thin film was prepared using the RF magnetron sputtering method. The physicochemical properties of the thin film were measured using X-ray diffraction and energy-dispersive X-ray spectrometry, while the antimicrobial activity of the bracket against common oral pathogenic microbes was assessed on the basis of colony counts. The rate of antimicrobial activity of the bracket coated with nano-TiO(2-x)N(y) thin film against Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscous, and Candida albicans was 95.19%, 91.00%, 69.44%, and 98.86%, respectively. Scanning electron microscopy showed that fewer microbes adhered to the surface of this newly designed bracket than to the surface of the normal edgewise bracket. The brackets coated with the N-doped TiO(2-x)N(y) thin film showed high antimicrobial and bacterial adhesive properties against normal oral pathogenic bacterial through visible light, which is effective in prevention of enamel demineralization and gingivitis in orthodontic patients.

Cao B; Wang Y; Li N; Liu B; Zhang Y

2013-01-01

210

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.

2005-01-01

211

Microscale meshes of Ti3O5 nano- and microfibers prepared via annealing of C-doped TiO2 thin films  

International Nuclear Information System (INIS)

Highlights: ? A new technique to achieve randomized microscale meshes composed of Ti3O5 nano- and microscale fibers is presented. ? The structure was obtained by thermal annealing of carbon-doped TiO2 thin films (with two different carbon concentration: 1.5 wt% and 3 wt%). ? The properties are investigated by different characterization techniques. - Abstract: A new technique to produce microscale Ti3O5 nano- and microfiber meshes is proposed. When a 3 wt% carbon-doped TiO2 film on Si(1 0 0) was annealed at 1000 deg. C in wet nitrogen (0.8%H2O), the amorphous TiO2 phase gave rise to crystalline phases of ?-Ti3O5 (75%) and rutile + trace of TiO2-xCx (25%). From Raman and FTIR Spectroscopy results, it was concluded that rutile is formed at the inner layer located at the interface between the mesh and the Si that was located away from the surface such that the meshes of nano- and microfibers are predominantly composed of Ti3O5 grown from the reaction of rutile with Si to form Ti3O5 and SiO2. On the other hand, it was noteworthy that the microscale mesh of nano- and microfibers showed increased photoluminescence compared with amorphous TiO2. The PL spectrum which had a broad band in the visible spectrum, fitted as three broad Gaussian distributions centered at 571.6 nm (?2.2 eV), 623.0 nm (?2.0 eV) and 661.9 nm (?1.9 eV).

2011-09-15

212

Influence of post annealing on optical and structural properties of Eu and Pd-doped TiO2 thin films  

Directory of Open Access Journals (Sweden)

Full Text Available This work presents optical and structural characterization of europium and palladium doped titanium dioxide thin films prepared by modified magnetron sputtering. The metallic Eu and Pd dopants have been co-sputtered from a base Ti target (mosaic target) and deposited on SiO2 substrates. After the deposition samples were additionally annealed in air ambient for 2 hours at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C, respectively. Structural properties of TiO2:(Eu, Pd) thin films were examined using X-ray diffraction (XRD). XRD patterns recorded after thermal treatment showed the dominating TiO2-rutile phase, independently of the temperature of annealing. Optical properties were studied as defined by optical transmission. It has been shown, that doping shifts the fundamental absorption edge of TiO2 toward the longer wavelength range. As the samples were additionally annealed the band gap widening has been observed from 1.7 eV, for as deposited sample up to 2.31 eV for those annealed at 800 °C.

Jaroslaw DOMARADZKI; Agnieszka BORKOWSKA; Danuta KACZMAREK; Artur PODHORODECKI; Jan MISIEWICZ

2007-01-01

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(CN)6]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(CN)6]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(CN)6]4?. That is, the TiO2 nanosurface responds to [Fe(CN)6]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(CN)6]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; Hirohito Ueno; Junichi Nemoto

2011-01-01

215

Fabrication of a pure TiO2 thin film using a self-polymeric titania nano-sol and its properties.  

UK PubMed Central (United Kingdom)

A pure TiO2 thin film without adding any organic binder was fabricated by using a self-polymeric titania nano-sol (14 mass%), which was prepared by the acid peptization method. The particle size distribution in the 14 mass% TiO2 sol, in which almost of particles had a size below 10.2 nm and the crystal phase confirmed by X-ray diffraction analysis was anatase. The diluted nano-sol had a capability to form a thin film at a low temperature (100-400 degrees C) on the slide glass by dipping method. The average thickness of a coating film was measured to be about 0.25-0.30 microm. A coated film had a high refractive index over 1.88 at least irrespective of the heat-treatment even at room temperature drying and showed a super-hydrophilicity (< 5 degrees) after 20 minutes under Ultra Violet light irradiation, and it sustained in the darkness during a long period over 7 days depending on the heat-treatment conditions. Atomic Force Microscopic observation shows that the morphology of a heat-treated film had a relationship with the long-term hydrophilicity in the darkness.

Park WK; Song JH; Kim SR; Kim TH; Iwasaki M

2012-02-01

216

Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.  

UK PubMed Central (United Kingdom)

In this paper, we investigated the sensing properties of sandwich structure of TiO2?Pd?TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2?Pd?TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2?Pd?TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240?°C.

Wang H; Sun Q; Chen L; Zhao Y

2013-09-01

217

Characterization of Cr–N codoped anatase TiO2(001) thin films epitaxially grown on SrTiO3(001) substrate  

Science.gov (United States)

We investigate the growth of Cr–N codoped anatase TiO2(001) thin films, prepared with a pulsed-laser-deposition (PLD) method using a mixed Cr2O3 and TiN ceramic target (6 at.% Cr), and characterized using scanning tunneling microscopy (STM), X-ray and ultraviolet photoemission spectroscopy (XPS/UPS), and ultraviolet–visible (UV–Vis) absorption spectroscopy. We find that the doping concentration of N in the films can be finely tuned by the O2 pressure and the growth temperature. By optimizing the growth conditions, we obtain the anatase TiO2(001) films with relatively smooth (1 × 4) reconstructed surface at equally codoped contents of 6 at.% Cr and 6 at.% N. The roughness of the surface is about 0.9 nm in root mean square, and the typical size of the (1 × 4) terraces is about 20 nm. The XPS results indicate that Cr and N should be both substitutionally doped in the film. From the UPS spectrum for the codoped film, the valence band maximum is significantly lifted by about 1.3 eV, indicating a narrowing band gap of 1.9 eV. The optical absorption spectrum shows that the codoped film noticeably absorbs the light at less than 710 nm. Derived from the optical absorption spectrum, an estimated band gap value of 1.78 eV is obtained, which is consistent with the UPS result.

Wang, Yang; Cheng, Zhengwang; Tan, Shijing; Shao, Xiang; Wang, Bing; Hou, J. G.

2013-10-01

218

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 Al2 (more) O3 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.

Tiznado, H.; Domínguez, D.; Cruz, W. de la; Machorro, R.; Curiel, M.; Soto, G.

2012-12-01

219

Manipulation of metal-insulator transition characteristics in aspect ratio-controlled VO2 micro-scale thin films on TiO2 (001) substrates  

Science.gov (United States)

We manipulated the metal-insulator transition characteristics of VO2 thin films on TiO2 (001) substrates by changing their micro-scaled metallic domain configurations through size- and aspect ratio-control. A very steep resistance drop at 294 K was demonstrated for a 1D parallel domain configuration in a low aspect ratio sample, whereas a multi-level resistance change was exhibited for a 1D series domain configuration in a high aspect ratio sample. This difference was explained using simple resistor models. The results illustrate the importance of spatially distributed metallic domain positions in tuning electrical transport properties.

Ueda, Hiroki; Kanki, Teruo; Tanaka, Hidekazu

2013-04-01

220

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

International Nuclear Information System (INIS)

[en] 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

 
 
 
 
221

Tuning of the surface plasmon resonance in TiO2/Au thin films grown by magnetron sputtering: The effect of thermal annealing  

Science.gov (United States)

Nanocomposites consisting of a dielectric matrix, such as TiO2, with embedded noble metal nanoparticles (NPs) possess specific optical properties due to the surface plasmon resonance (SPR) effect, interesting for several applications. The aim of this work is to demonstrate that these properties are sensitive to the nanostructure of magnetron-sputtered TiO2/Au thin films, which can be tuned by annealing. We study the role of the shape and size distribution of the NPs, as well as the influence of the crystallinity and phase composition of the host matrix on the optical response of the films. All these characteristics can be modified by vacuum annealing treatments of the deposited films. A theoretical interpretation and modeling of the experimental results obtained is presented. The model involves a modified Maxwell-Garnett approach for the effective dielectric function of the composite (describing the SPR effect) and the transfer matrix formalism for multilayer optics. Input data are based on the experimental information obtained from the detailed structural characterization of the films. It is shown that the annealing treatments can be used for controlling the optical properties of the composite films, making them attractive for decorative coatings.

Torrell, M.; Kabir, R.; Cunha, L.; Vasilevskiy, M. I.; Vaz, F.; Cavaleiro, A.; Alves, E.; Barradas, N. P.

2011-04-01

222

Study of structural and optical properties of TiO2:Tb thin films prepared by high energy reactive magnetron sputtering method  

Directory of Open Access Journals (Sweden)

Full Text Available This work is focused on structural and optical properties of TiO2 thin films doped with different amount of terbium. The thin films have been prepared by high energy reactive magnetron sputtering (HE RMS) and by low pressure hot target reactive magnetron sputtering (LP HTRS) processes. Thin films were deposited from mosaic, metallic Ti-Tb target sputtered under oxygen plasma (without argon) at a pressure below 10–1 Pa. Structural examinations show nanocrystalline nature of prepared thin films with either anatase or rutile phases depending on concentration of Tb 0.4 at.% and 2.6 at.%, respectively. The phase transformation from the anatase to the rutile has not been observed after additional post-deposition annealing even at the temperature up to 1000 K. Based on investigations performed with the help of atomic force microscope high nanocrystalline, close-packed structure has been found. Studies of refraction index revealed higher value for the thin films prepared by the HE RMS than by the LP HTRS methods.

Jaroslaw Domaradzki; Danuta Kaczmarek; Eugeniusz L. Prociow; Damian Wojcieszak; Karolina Sieradzka; Michal Mazur; Marcin Lapinski

2009-01-01

223

Magnetic properties of epitaxial Co-doped anatase TiO2 thin films with excellent structural quality  

Energy Technology Data Exchange (ETDEWEB)

The heteroepitaxy of Co-doped anatase TiO2 on LaAlO3(001) has been refined with the goal of determining the relationship between structural quality and magnetic ordering. By significantly reducing the deposition rate and substrate temperature, well-ordered Co:TiO2 films with unprecedented crystalline quality were obtained by oxygen-plasma-assisted molecular beam epitaxy, as characterized by x-ray diffraction. These films exhibit uniform Co doping, with no evidence of Co segregation or secondary phases throughout the film depth or on the surface. Despite the improvement in crystalline quality and Co distribution, the films exhibit negligible ferromagnetism, with saturation moments of only ~0.1 ?B/Co. This loss of ferromagnetism is in stark contrast to faster-grown Co:TiO2 films, where a higher growth rate and substrate temperature typically result in lower crystalline quality, a highly non-uniform Co distribution, and average saturation moments of ~1.2 ?B/Co. The presence of ferromagnetism in faster-grown Co:TiO2 does not appear to arise from intrinsic point defects present in the bulk material, such as charge-compensating oxygen vacancies, but is instead attributed to the presence of extended structural defects.

Kaspar, Tiffany C.; Droubay, Timothy; McCready, David E.; Nachimuthu, Ponnusamy; Heald, Steve M.; Wang, Chong M.; Lea, Alan S.; Shutthanandan, V.; Chambers, Scott A.; Toney, Michael F.

2006-07-26

224

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

International Nuclear Information System (INIS)

[en] 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

2006-01-01

225

Annealing of TiO2 Films Deposited on Si by Irradiating Nitrogen Ion Beams  

International Nuclear Information System (INIS)

[en] Thin TiO2 films were deposited on Si at a temperature of 600 deg. C by an ion beam assisted deposition (IBAD) method. The TiO2 films were annealed for 30 min in Ar at temperatures below 700 deg. C. The as-deposited TiO2 films had high permittivities such 200 ?o and consisted of crystallites that were not preferentially oriented to the c-axis but had an expanded c-axis. On the annealed TiO2 films, permittivities became lower with increasing annealing temperature, and crystallites were oriented preferentially to the (110) plane

2006-11-13

226

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

227

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.

1620-01-00

228

Fabrication of TiO2 Colloidal Crystal Films and Characterization of Their Photocatalytic Properties  

Energy Technology Data Exchange (ETDEWEB)

We have studied hydrolysis of organic alkyltitanate compounds and optimized reaction condition for synthesis of monodisperse titania (TiO2 colloidal particles with controlled size from nanometer to submicron. The synthesized TiO2 colloidal particles were further surface-modified with hydrophobic silane coupling agent. With the monodisperse hydrophobic particles, we fabricated TiO2 colloidal crystal thin films through transferring self-assembled colloidal crystal monolayer from water surface onto solid substrates. The TiO2 colloidal crystal films exhibit enhanced interaction with visible light. Consequently, in comparison with plain TiO2 particle thin film, the thin film with colloidal crystal structure shows enhanced photocatalytic activity, as evaluated through photodegradation of organic dye methyl orange in solution under simulated solar light.

Huang, Wei [Zaozhuang University, People' s Republic of China; Wang, Feng [Zaozhuang University, People' s Republic of China; Wang, Wei [ORNL

2011-01-01

229

Thin nanocrystalline TiO2-SnO2 sprayed films: Influence of the dopant concentration, substrate and thermal treatment on the phase composition and crystallites sizes  

International Nuclear Information System (INIS)

Thin nanocrystalline TiO2-SnO2 films (0-50 mol% SnO2) are coated on quartz and stainless steel substrates by spray pyrolysis method. The synthesized films are investigated by XRD, Raman spectroscopy and XPS. The diffraction peaks of anatase phase fade while the peaks of rutile phase appear in the X-ray profiles with increasing of the treatment temperature and the content of SnO2 in the sprayed films. It is found that SiO2 coming from the quartz substrate stabilizes the anatase phase up to 700 oC. A more pronounced crystallization of rutile is registered with the films deposited on stainless steel substrate, which probably is caused by combined effect of SnO2 doping and penetration of iron and chromium from the substrate inside the films. Dopant concentration (SnO2) influences the size of the crystallites of the titania films deposited on quartz substrates The size of crystallites in the titania films decreases from 45 to 25 nm with increasing of SnO2 amount. The SnO2 amount does not affects substantially the size of crystallites (about 23 nm) for the films deposited on stainless steel.

2010-01-07

230

Layer-by-layer assembling TiO2 film from anatase TiO2 sols as the photoelectrochemical sensor for the determination of chemical oxygen demand  

International Nuclear Information System (INIS)

Highlights: ? The anatase TiO2 sols containing 5 nm nanocrystals were prepared by the peptization of trifluoroacetic acid for the first time. ? The anatase TiO2 sols were used to prepare TiO2 thin films, and the films were employed as a photo-electrochemical sensor for the determination of chemical oxygen demand (COD). ? The COD detection limit of 1 mg L?1 with a working range of 0–130 mg L?1 was achieved with the layer-by-layer TiO2 films. - Abstract: Anatase TiO2 sols containing ultrafine TiO2 crystallites (ca. 5 nm) were prepared by the peptization of amorphous precipitates in trifluoroacetic acid (TFA) solution. The crystallite size of TiO2 in the sols was tuned by the subsequently hydrothermal treatment. The as-prepared TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectrometry, UV–vis absorption spectrometry and transmission electron microscopy. The positive charged nanoparticles in the sol with the Ti/TFA molar ratio of 1:8 and the poly(styrene sulfonic acid) sodium salt solution were used to prepare TiO2 thin films by a layer-by-layer (LBL) self assembly method. Since the compact structure of the LBL thin films was good for the electronic transport, the TiO2 LBL thin films were introduced to be working electrodes in three-electrode photoelectrochemical cells. The 15-layer TiO2 thin film electrode showed a high photoelectrochemical property and it was employed as a sensor for the chemical oxygen demand. The detection limit of 1 mg L?1 with a working range of 0–130 mg L?1 was achieved. The relative standard deviation was 3.56% for 30 repetitive detections of 200 ?M glucose with the theoretical COD value of 38.4 mg L?1 COD.

2016-01-00

231

Optical properties of TiO2-x thin films studied by spectroscopic ellipsometry: substrate temperature effect  

Science.gov (United States)

Titanium oxide thin films were obtained by reactive dc-magnetron sputtering. A target of titanium (Lesker; 99.9% pure) and a mixture of argon and oxygen gases were used to deposit titanium oxide films onto silicon and glass substrates. The substrate temperature was varied between 200 and 400°C. Optical constants have been determined by spectroscopic ellipsometry and by using the optical transmittance data from UV-Vis spectrometry. The effect of substrate temperature on the optical properties is analyzed. Results indicate an increase in the refractive index of the films with substrate temperature, which is attributed to changes in the oxygen content, density and degree of crystallization of the films.

Camacho-Lopez, M. A.; Sanchez-Perez, Celia A.; Esparza-Garcia, A.; Ghibaudo, E.; Rodil, S.; Muhl, S.; Escobar-Alarcon, L.

2004-10-01

232

Comparison of hydrophilic properties of TiO2 thin films prepared by sol-gel method and reactive magnetron sputtering system  

International Nuclear Information System (INIS)

This article reports on preparation, characterization and comparison of TiO2 films prepared by sol-gel method using the titanium isopropoxide sol (TiO2 coating sol 3%) as solvent precursor and reactive magnetron sputtering from substoichiometric TiO2-x targets of 50 mm in diameter. Dual magnetron supplied by dc bipolar pulsed power source was used for reactive magnetron sputtering. Depositions were performed on unheated glass substrates. Comparison of photocatalytic properties was based on measurements of hydrophilicity, i.e. evaluation of water contact angle on the film surface after UV irradiation. It is shown, that TiO2 films prepared by the sol-gel method exhibited higher hydrophilicity in the as-deposited state but has significant deterioration of hydrophilicity during aging, compared to TiO2 films prepared by magnetron sputtering. To explain this effect AFM, SEM and high resolution XPS measurements were performed. It is shown that the deterioration of hydrophilicity of sol-gel TiO2 films can be suppressed if as-deposited films are exposed to the plasma of microwave oxygen discharge.

2011-08-01

233

Optical modeling of nanocrystalline TiO2 films.  

UK PubMed Central (United Kingdom)

The light transmittance, T, in nanocrystalline TiO2 films was studied as a function of the light wavelength, lambda, the nanocrystal radius, a, and the film thickness, d. Two types of TiO2 nanoparticles were employed: a commercial powder (P25) and synthesized particles from titanium isopropoxide (SP). The X-ray diffraction measurements revealed that both P25 and SP are mainly anatase and the average crystal sizes, 2a, of P25 and SP are 50.3 and 23.7 nm, respectively. Despite the visual difference between micron-order thin films of P25 and SP, the light hemispherical transmittance corrected with the surface specular reflectance has a clear dependence of ln(T) = -0.5beta lambda(-4)a(3)d, with beta = 1.5 x 10(3) from visible to near-infrared wavelengths. The dependence and beta value were successfully explained by the simplest model on the basis of the Rayleigh scattering theory. This indicates that the nanocrystalline TiO2 thin films are a typical medium where the simplest scattering model is a good approximation. However, the model was inapplicable to light scattering in relatively thick P25 films of 1.5-3.0 microm because of nonnegligible internal multiple scattering. For the moderate thickness films, ln(T) proportional to lambda(gamma), where gamma increases from -4 in proportion to the film thickness is an alternative approximation. With these light scattering models, the light absorption rate of the TiO2 crystal was successfully evaluated from experimental extinction rates.

Usami A; Ozaki H

2005-02-01

234

Influence of TiO2 nanoparticles on the optical and structural properties of PPV thin films converted at low temperatures  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we studied the optical properties of poly(p-phenylene vinylene) (PPV) produced by the thermal conversion of a precursor polymer blended with a synthetic dye (Reactive Black 5). The production of PPV by this method decreases the overall time and cost of the process. We observed that the introduction of the dye resulted in an additional absorbance band near 550–700 nm, which can be beneficial to the photon harvesting capacity of the polymer if it is used as the donor material in a photovoltaic device. We studied how the optical and structures properties of this blend change when different quantities of TiO2 nanoparticles are introduced. For that, thin films were produced by the cast deposition of pre-PPV:dye:TiO2. The scanning electronic microscopic images showed that the inorganic semiconductor form large agglomerates of approximately 200 nm, indicating a very rough surface where the dye can be adsorbed. The analysis of photoluminescence and Raman peaks indicated a reduction of the mean conjugation length of the polymer chains in the presence of TiO2 nanoparticles.

B. Rostirolla; E. Laureto; M. A. T. da Silva; H. de Santana; I. F. L. Dias; J. L. Duarte

2013-01-01

235

Carrier recombination-incited substrate vibrations after pulsed UV-laser photolysis of TiO2 thin single-crystal plate and nanoparticle films.  

UK PubMed Central (United Kingdom)

Photo-induced carrier generation and recombination have been regarded as important steps in understanding the photocatalytic reactions on the surfaces of semiconductors such as TiO2. During the investigation of a photocatalytic water-splitting reaction on the surface of semiconductor TiO2 (rutile) single-crystal plate and sintered-nanoparticle (anatase) films coated on a CaF2 plate, a pulsed 355 nm laser was used for band-gap excitation and a continuous-working, mid-infrared laser as the probe to trace the kinetics of the photogenerated electrons. Fast oscillations with periods of 10-50 ?s were observed. We demonstrated experimentally that these oscillations are neither from the nonlinear carrier recombination dynamics nor surface chemical reactions; instead, they are caused by the thermal-induced flexural vibrations initiated by the fast carrier recombination in the light-absorbing area. The observed oscillations can be well accounted for by thermal stress-induced flexural vibrations of the substrates due to rapid charge recombination, and the observed oscillation frequencies match the flexural vibration frequencies predicted by the Kirchhoff-Love thin-plate theory. Light-interference effect caused by the beam reflecting off the surfaces of the substrate and windows, which can amplify the oscillation signals, is also discussed. Several approaches are proposed to minimize or eliminate the interference from the substrate vibration in the transient kinetic measurement when a coherent laser is used as the probe beam.

Zhu M; Zhu G; Weng Y

2013-05-01

236

Carrier recombination-incited substrate vibrations after pulsed UV-laser photolysis of TiO2 thin single-crystal plate and nanoparticle films.  

Science.gov (United States)

Photo-induced carrier generation and recombination have been regarded as important steps in understanding the photocatalytic reactions on the surfaces of semiconductors such as TiO2. During the investigation of a photocatalytic water-splitting reaction on the surface of semiconductor TiO2 (rutile) single-crystal plate and sintered-nanoparticle (anatase) films coated on a CaF2 plate, a pulsed 355 nm laser was used for band-gap excitation and a continuous-working, mid-infrared laser as the probe to trace the kinetics of the photogenerated electrons. Fast oscillations with periods of 10-50 ?s were observed. We demonstrated experimentally that these oscillations are neither from the nonlinear carrier recombination dynamics nor surface chemical reactions; instead, they are caused by the thermal-induced flexural vibrations initiated by the fast carrier recombination in the light-absorbing area. The observed oscillations can be well accounted for by thermal stress-induced flexural vibrations of the substrates due to rapid charge recombination, and the observed oscillation frequencies match the flexural vibration frequencies predicted by the Kirchhoff-Love thin-plate theory. Light-interference effect caused by the beam reflecting off the surfaces of the substrate and windows, which can amplify the oscillation signals, is also discussed. Several approaches are proposed to minimize or eliminate the interference from the substrate vibration in the transient kinetic measurement when a coherent laser is used as the probe beam. PMID:23643039

Zhu, Ming; Zhu, Gangbei; Weng, Yuxiang

2013-05-01

237

Time-resolved optical emission spectroscopy during pulsed dc magnetron sputter deposition of Ti and TiO2 thin films  

International Nuclear Information System (INIS)

Time-resolved optical emission spectroscopy is applied to analyse pulsed dc magnetron plasmas during sputter deposition of Ti and TiO2 thin films. The studies are focused on the temporal behaviour of emissions of selected atomic titanium, argon and oxygen during the 'on-time', when the magnetron plasma source is turned on, and during the 'reverse-time', when the magnetron plasma source is turned off. Single and double exponential decays of the optical emissions were found during the 'reverse-time'. During the 'on-time', we observed a rapid increase in some emissions with a more or less pronounced overshoot and a slow increase in other emissions which follow the temporal evolution of the conduction current. The various time constants can be related to the dynamics of the fast electrons, the Ar metastables, the Ti atoms (metallic mode) and the O atoms (oxide mode).

2006-01-01

238

Photocatalytic degradation of methylene blue using undoped and Ag-doped TiO2 thin films deposited by a sol-gel process: Effect of the ageing time of the starting solution and the film thickness  

International Nuclear Information System (INIS)

Undoped and Ag-doped TiO2 thin films were deposited on glass substrates by the sol-gel method. A novel propose to prepare the solution is the use of titanium monohydrate oxyacetyl acetonate as the starting reagent. The effect of the ageing time of the starting solution as well as the number of coatings on the photocatalytic degradation of methylene blue (MB) was studied. The variation of the absorption spectra shows the degradation of MB dissolved in water, as a result of the reaction produced on the surface of the films, and promoted by ultraviolet irradiation during 5 h. The results show an optimum photocatalytic activity, in the order of 35%, presented in the 5-immersion Ag-doped TiO2 thin films, deposited from 7- and 14-day aged solutions. On the other hand, the Ag-doped TiO2 films deposited at different coatings show small changes in the photocatalytic activity. Morphological studies show the presence of silver particles on the film surface, due to the different number of coatings, affecting the photocatalytic performance.

2010-10-25

239

UV protection of reduced graphene oxide films by TiO2 nanoparticle incorporation.  

UK PubMed Central (United Kingdom)

A simple strategy for preparation of reduced graphene oxide (RGO)/TiO2 hybrid thin films was developed by UV-assisted incorporation of TiO2 nanoparticles (NPs) onto RGO films. The UV-assisted incorporation of TiO2 NPs onto RGO films makes the hybrid films stable against prolonged exposure to UV light without the decrease of their conductivity and transparency.

Kim YK; Min DH

2013-05-01

240

Formation of smooth and rough TiO2 thin films on fiberglass by sol-gel method  

Directory of Open Access Journals (Sweden)

Full Text Available Se ha usado la inmersión de substratos en un sol-gel hecho de un composito para preparar películas delgadas de TiO2 ya sean lisas o rugosas sobre fibra de vidrio. La deposición de películas se hizo desde una solución de isopropóxido de titanio (IV) como precursor del sol-gel y bromuro de cetil-trimetil-amonio como surfactante. Las muestras fueron caracterizadas usando las técnicas de espectroscopia Raman y Uv-visible, así como la microscopia electrónica de barrido y de fuerza atómica. En casos especiales, la deposición de película consiste en un gel precursor de titanio que encapsula micelas de surfactante. La película de gel es convertida a la fase anatasa por calcinación a 500 °C, las películas lisas de TiO2 pueden tener propiedades ópticas y protectoras y la rugosidad de las películas de TiO2 puede aumentar su inherente actividad foto catalítica.

Jorge Medina-Valtierra; Manuel Sánchez-Cárdenas; Claudio Frausto-Reyes; Sergio Calixto

2006-01-01

 
 
 
 
241

Preparation of large-pore mesoporous nanocrystalline TiO2 thin films with tailored pore diameters.  

UK PubMed Central (United Kingdom)

A novel and facile synthesis route to large-pore mesoporous nanocrystalline anatase thin films with tunable pore diameters in narrow distribution of sizes ranging from 8.3 to 14 nm is reported, using triblock copolymer as the template and Ti(OBu(n))4 as the inorganic precursor. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. A reasonable formation mechanism is also presented in this work.

Liu K; Fu H; Shi K; Xiao F; Jing L; Xin B

2005-10-01

242

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

243

Effects of acid catalyst type on structural, morphological, and optoelectrical properties of spin-coated TiO2 thin film  

Science.gov (United States)

The effects of different acid catalysts of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, and citric acid on structural, morphological, and optoelectrical properties of nanocrystalline spin-coated TiO2 thin films synthesized via alkoxide sol–gel route were investigated. It was found that only the sols with HNO3 and HCl are suitable for film preparation. The X-ray diffractometry and Raman analysis showed that crystalline phases could be controlled by the type of acid catalyst. Although the H2SO4 sol shows good stability, it causes extremely different morphology to form due to its different sol nature and high contact angle. Fourier transformed infrared spectra confirmed the presence of acid anion species in all samples even after calcination. Furthermore, it was inferred from UV–visable absorption spectra that although the band gap and thickness of the films are independent of acid catalyst type, the refractive index and porosity of the films are strongly affected by the type of acids.

Golobostanfard, Mohammad Reza; Abdizadeh, Hossein

2013-03-01

244

Synthesis and Growth Mechanism of Thin-Film TiO2 Nanotube Arrays on Focused-Ion-Beam Micropatterned 3D Isolated Regions of Titanium on Silicon.  

UK PubMed Central (United Kingdom)

In this paper, the fabrication and growth mechanism of net-shaped micropatterned self-organized thin-film TiO2 nanotube (TFTN) arrays on a silicon substrate are reported. Electrochemical anodization is used to grow the nanotubes from thin-film titanium sputtered on a silicon substrate with an average diameter of ?30 nm and a length of ?1.5 ?m using aqueous and organic-based types of electrolytes. The fabrication and growth mechanism of TFTN arrays from micropatterned three-dimensional isolated islands of sputtered titanium on a silicon substrate is demonstrated for the first time using focused-ion-beam (FIB) technique. This work demonstrates the use of the FIB technique as a simple, high-resolution, and maskless method for high-aspect-ratio etching for the creation of isolated islands and shows great promise toward the use of the proposed approach for the development of metal oxide nanostructured devices and their integration with micro- and nanosystems within silicon-based integrated-circuit devices.

Amani Hamedani H; Lee SW; Al-Sammarraie A; Hesabi ZR; Bhatti A; Alamgir FM; Garmestani H; Khaleel MA

2013-09-01

245

Metal-to-Insulator Transition in Anatase TiO2 Thin Films Induced by Growth Rate Modulation  

Energy Technology Data Exchange (ETDEWEB)

We demonstrate control of the carrier density of single phase anatase TiO{sub 2} thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO{sub 2} samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.

Tachikawa, T; Minohara, M.; Nakanishi, Y.; Hikita, Y.; Yoshita, M.; Akiyama, H.; Bell, C.; Hwang, H.Y.

2012-06-21

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.

2012-01-01

247

Structure of epitaxial (Fe,N) codoped rutile TiO2 thin films by x-ray absorption  

Energy Technology Data Exchange (ETDEWEB)

Homoepitaxial thin films of Fe:TiO2 and (Fe,N):TiO2 were deposited on rutile(110) by molecular beam epitaxy. X-ray absorption near edge spectroscopy (XANES) spectra were collected at the Ti L-edge, Fe L-edge, O K-edge, N K-edge, and Ti K-edge. No evidence of structural disorder associated with a high concentration of oxygen vacancies is observed. Substitution of Fe for Ti could not be confirmed, although secondary phase Fe2O3 and metallic Fe can be ruled out. The similarity of the N K-edge spectra to O, and the presence of a strong x-ray linear dichroism (XLD) signal for the N K-edge, indicates that N is substitutional for O in the rutile lattice, and is not present as a secondary phase such as TiN. Simulations of the XANES spectra qualitatively confirm substitution, although N appears to be present in more than one local environment. Neither Fe:TiO2 nor (Fe,N):TiO2 exhibit intrinsic room temperature ferromagnetism, despite the presence of mixed valence Fe(II)/Fe(III) in the reduced (Fe,N):TiO2 film.

Kaspar, Tiffany C.; Ney, A.; Mangham, Andrew N.; Heald, Steve M.; Joly, Yves; Ney, V.; Wilhelm, F.; Rogalev, A.; Yakou, Flora; Chambers, Scott A.

2012-07-23

248

Ultrafast dynamics of the indoline dye D149 on electrodeposited ZnO and sintered ZrO2 and TiO2 thin films.  

UK PubMed Central (United Kingdom)

The ultrafast photoinjection and subsequent relaxation steps of the indoline dye D149 were investigated in detail for a mesoporous electrodeposited ZnO thin film and compared with experiments on sintered TiO(2) and ZrO(2) thin films, all in contact with air, using pump-supercontinuum probe (PSCP) transient absorption spectroscopy in the range 370-770 nm. D149 efficiently injects electrons into the ZnO surface with time constants from ?70 fs (time-resolution-limited) up to 250 fs, without the presence of slower components. Subsequent spectral dynamics with a time constant of 20 ps and no accompanying change in the oscillator strength are assigned to a transient Stark shift of the electronic absorption spectrum of D149 molecules in the electronic ground state due to the local electric field exerted by the D149?(+) radical cations and conduction band electrons in ZnO. This interpretation is consistent with the shape of the relaxed PSCP spectrum at long times, which resembles the first derivative of the inverted steady-state absorption spectrum of D149. In addition, steady-state difference absorption spectra of D149?(+) in solution from spectroelectrochemistry display a bleach band with distinctly different position, because no first-order Stark effect is present in that case. Interference features in the PSCP spectra probably arise from a change of the refractive index of ZnO caused by the injected electrons. The 20 ps component in the PSCP spectra is likely a manifestation of the transition from an initially formed bound D149?(+)-electron complex to isolated D149?(+) and mobile electrons in the ZnO conduction band (which changes the external electric field experienced by D149) and possibly also reorientational motion of D149 molecules in response to the electric field. We identify additional spectral dynamics on a similar timescale, arising from vibrational relaxation of D149?(+) by interactions with ZnO. TiO(2) exhibits similar dynamics to ZnO. In the case of ZrO(2), electron injection accesses trap states, which exhibit a substantial probability for charge recombination. No Stark shift is observed in this case. In addition, the spectroelectrochemical experiments for D149?(+) in dichloromethane and acetonitrile, which cover the spectral range up to 2000 nm, provide for the first time access to its complete D(0)? D(1) absorption band, with the peak located at 1250 and 1055 nm, respectively. Good agreement is obtained with results from DFT/TDDFT calculations of the D149?(+) spectrum employing the MPW1K functional.

Oum K; Lohse PW; Flender O; Klein JR; Scholz M; Lenzer T; Du J; Oekermann T

2012-11-01

249

Effect of oxygen partial pressure on the structural and electrical properties of DC sputtered (Ta2O5)0.85(TiO2)0.15 thin films on Si  

Science.gov (United States)

Thin films of (Ta2O5)0.85(TiO2)0.15) were deposited on p-Si (100) by DC reactive magnetron sputtering at various oxygen partial pressures in the range 3×10-2 - 9×10-2 Pa and annealed in air for 1 hour at 700°C. The structural properties of the (Ta2O5)0.85(TiO2)0.15 films were studied and the electrical properties of Al/ (Ta2O5)0.85(TiO2)0.15 gate stacks formed on p-Si substrates were systematically investigated. The leakage current density of the films deposited at 3×10-2 Pa was 6.97×10-6 A/cm2 (at a gate bias voltage of 1.5 V) and it was decreased to 1.75×10-8 A/cm2 with the increase of oxygen partial pressure to 9×10-2 Pa. The current conduction mechanism of the (Ta2O5)0.85(TiO2)0.15 films was analyzed and compared with mechanisms of Poole-Frenkel and Schottky emissions.

Uthanna, S.; Sekhar, M. Chandra

2012-06-01

250

Influence of a TiO2 buffer layer on the magnetic properties of anatase Co:TiO2 thin films  

International Nuclear Information System (INIS)

[en] Our study addresses the influence of a TiO2 buffer layer on the morphological, structural, and magnetic properties of Co:TiO2 films grown on (001) SrTiO3 substrates by RF sputtering. We demonstrate that a direct correlation exist between the morphology, the Co heterogeneity, and the magnetic properties measured in the films. Correlated analysis by cross section transmission electron microscopy, energy dispersive x-ray, and x-ray photoemission spectroscopy reveals that the Co is not uniformly distributed in the film but concentrated in the surface clusters. Atomic force microscopy analysis illustrates that the unbuffered films present a large density of surface clusters. These clusters are not metallic Co but Co rich TiO2 anatase phase and they are accompanied by structural defects in the film: dislocations, small angle grain boundaries. Magnetometry analysis shows that the unbuffered films have a net ferromagnetic behavior, while in the buffered ones the ferromagnetism is quenched. Therefore, we conclude that the magnetism in unbuffered samples is related to the surface clusters and seems to have an extrinsic nature.

2012-04-15

251

Effect of SnO2 on the photocatalytical properties of TiO2 films  

International Nuclear Information System (INIS)

TiO2/SnO2 thin films with different tin atomic percentages were successfully prepared on glass substrates by the spray pyrolysis method from an alcoholic solution of TiO[C5H7O2]2 with different concentrations of SnCl4. The TiO2/SnO2 thin films prepared at 450 deg. C presented the anatase phase in polycrystalline configuration from %Sn = 0 in the starting solution up to %Sn = 20, at higher tin content the films present an amorphous configuration. The resulting thin films have a homogeneous surface structure with some porosity. The photocatalytical properties of the films were evaluated with the degradation of methylene blue. The products of the degradation reaction were identified by 1H nuclear magnetic resonance and the film properties were studied by atomic force microscopy, scanning electron microscopy, UV-Vis spectroscopy, and X-ray diffraction.

2005-11-01

252

Solar photocatalytic degradation of phenol using pyrolitic TiO2 films deposited inside a tubing  

International Nuclear Information System (INIS)

Solar photocatalytic degradation of phenol was obtained using TiO2 films deposited inside glass tubing. TiO2 thin films inside tubing were obtained by spray-gel technique using a titanium isopropoxide solution conveniently diluted in ethanol. The gas carrier flux, air pressure and temperature were kept during deposition at 5 L/min, 200 kPa, and 200 oC, respectively. Experiments were performed using either the solar radiation or a 300 W lamp simulating the UVA solar radiation component. In order to concentrate the radiation a reflective surface was placed in the back part of the tube. The initial concentration of phenol solution was 20 ppm, and the phenol concentration during the experiment was followed using a standard colorimetric method when aminoantipirine reacts in the sample giving a colored complex. The volume of the phenol solution was limited with a solid aluminum rod placed axially to the glass tube. The obtained TiO2 films were amorphous, but after an annealing at 450oC for 1 h the films crystallize to anatase structure and present photocatalytic activity. The films morphology observed by scanning electron microscopy presented a uniform film and agglomerates of TiO2, the size of the agglomerates increases as Ti isopropoxide/ethanol molar ratio of the starting solution decreases. The precursor concentration solution and film thickness of TiO2 for phenol degradation was optimized. (author)

2005-01-01

253

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.

Natalie Smirnova; Yuriy Gnatyuk; Anna Eremenko; Gennadiy Kolbasov; Vera Vorobetz; Irina Kolbasova; Olga Linyucheva

2006-01-01

254

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.

Natalie Smirnova; Yuriy Gnatyuk; Anna Eremenko; Gennadiy Kolbasov; Vera Vorobetz; Irina Kolbasova; Olga Linyucheva

2006-01-01

255

Fabrication of TiO2 Thick Film for Photocatalyst from Commercial TiO2 Powder  

International Nuclear Information System (INIS)

Photocatalytic activity of TiO2 thick film ceramics made of commercial TiO2 powder has been studied. The TiO2 powder was nano sized one that was derived from dried TiO2 suspension. The TiO2 suspension was made by pouring some blended commercial TiO2 powder into some amount of water. The paste of TiO2 was made by mixing the nano sized TiO2 powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 deg. C and heated at different temperatures (400 deg. C and 500 deg. C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue.

2008-03-17

256

Strong electronic coupling and ultrafast electron transfer between PbS quantum dots and TiO2 nanocrystalline films.  

UK PubMed Central (United Kingdom)

Hot carrier and multiple exciton extractions from lead salt quantum dots (QDs) to TiO(2) single crystals have been reported. Implementing these ideas on practical solar cells likely requires the use of nanocrystalline TiO(2) thin films to enhance the light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron transfer time from PbS QDs to TiO(2) nanocrystalline thin films, suggesting the possibility of extracting hot carriers and multiple excitons in solar cells based on these materials.

Yang Y; Rodríguez-Córdoba W; Xiang X; Lian T

2012-01-01

257

The influence of TiO2 powder and film on the photodegradation of methyl orange  

International Nuclear Information System (INIS)

Recent investigation has showed that the semiconductor nano-powder or thin film, such as titanium dioxide suspended in water, can utilize ultraviolet light for photocatalytic oxidation of organic pollutants, such as dyes. The photocatalytic activity of TiO2 (powder or thin film) was tested in the reaction of photodegradation of methyl orange (MO). The effect of the initial concentration of dye, the pH, the amount and the type of TiO2 have been investigated. The films were prepared by doctor blade technique, and were annealed in air at various temperatures ranging from 300 to 500 deg. C. The thermal treatment increases the surface roughness of thin films. The best film (without fissures), with higher pores and small grains (150 nm) was the annealed one at 500 deg. C. The correlation between the measured contact angle and the films roughness estimated from atomic force microscopy (AFM) shows that a low contact angle (wetting behavior) corresponds to a higher porosity (a fractured structure, rich in edges and corners), and consequently to high surface energy. Kinetic analyses indicate that the photodegradation rates of dyes can usually be approximated as first-order kinetics for degradation mechanisms. Adsorption is a prerequisite for the TiO2-assisted photodegradation, and the extent of degradation has been discussed in terms of the Langmuir-Hinshelwood model. Thin-film coating of photocatalyst may solve the problems of leaching and separation. At a low concentration of MO (0.0125 mM) the efficiency of MO photodegradation is comparable in the case of thin film and powder of TiO2

2008-12-20

258

Photocatalytic performance of Fe-, Ni-, or Cu-ion implanted TiO2 films under UV light, visible light and sunlight irradiation  

Science.gov (United States)

TiO2 thin films were fabricated on microscope glass slides by sol-gel method. Then Fe, Ni or Cu ions were implanted in the films. XRD, XPS and UV-Vis spectrophotometer technologies were used to characterize the films. The results of photodegradation of methyl orange in aqueous solution demonstrate: (1) the films are of visible light response photocatalytic activity; (2) under UV light and sunlight excitation, all the films present less efficient than pure TiO2 film. The photodegradation effects of transition metal ion implanted TiO2 thin films were discussed.

Qin, L. Z.; Liang, H.; Liao, B.; Liu, A. D.; Wu, X. Y.; Sun, J.

2013-07-01

259

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

260

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

 
 
 
 
261

Improvement of (004) texturing by slow growth of Nd doped TiO2 films  

International Nuclear Information System (INIS)

In this work, we present preferred (004) texturing of sputter deposited titanium dioxide (TiO2) films on glass substrates as a consequence of Nd doping at very slow growth rate. Nd concentration was varied from 0.0 to 2.0 atomic percent (at. %) in TiO2 thin films deposited under identical growth conditions, i.e., the growth rate of 0.6 Å/s and at 500 °C. At 2 at. % Nd, complete texturing along (004) plane was observed, as indicated by the X-ray diffraction analyses. Morphology of the deposited TiO2 films from pure to 2 at. % Nd doped TiO2 films showed faceted to planar growth. Visualization of electrical and structural analysis (VESTA) software revealed that the change in the morphology was due to preferential growth in (004) orientation. Raman spectroscopy highlighted the phonon confinement in the Eg mode, and a red shift was observed due to an increase in the anti-symmetry in bonding with increased Nd concentration. XPS results confirmed the variation in oxygen vacancy concentration along with the reduction of Ti and Nd valance states with the change in the dopant concentration. Our experiments confirmed that the substitution of Nd at Ti sites was responsible for texturing in (004) orientation and this was possible by growing films at a very slow rate.

1971-01-00

262

Third-generation biosensors based on TiO2 nanostructured films  

International Nuclear Information System (INIS)

[en] 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

2005-06-03

263

Photocatalytic and superhydrophilicity properties of N-doped TiO2 nanothin films  

International Nuclear Information System (INIS)

Pure TiO2 and nitrogen doped titanium dioxide (N-TiO2) thin films were prepared by sol-gel method through spin coating on soda lime glass substrates. TiCl4 and urea were used as Ti and N sources in the sol. XRD results showed nitrogen doping has retarded anatase to rutile phase transformation. The doping also leads to a decrease in roughness of the samples from 4 nm (TiO2) to 1 nm (N-TiO2). However, surface analysis by statistical methods reveals that both surfaces have self-affine structure. Optical band gap of thin films was shifted from 3.65 eV (TiO2) to 3.47 eV (N-TiO2). Hydrophilic conversion and photocatalytic degradation properties of thin films were investigated and exhibited that N-TiO2 thin film has more preferable hydrophilicity and photocatalytic properties under UV illumination.

2011-06-01

264

Effect of a TiO2 Buffer Layer on the Properties of ITO Films Prepared by RF Magnetron Sputtering  

Directory of Open Access Journals (Sweden)

Full Text Available Sn-doped In2O3 (ITO) thin films were prepared by radio frequency magnetron sputtering without intentionalsubstrate heating on bare glass and TiO2-deposited glass substrates to investigate the effect of a TiO2 buffer layer onthe electrical and optical properties of ITO films. The thicknesses of TiO2 and ITO films were kept constant at 5 and100 nm, respectively. As-deposited ITO single layer films show an optical transmittance of 75.9%, while ITO/TiO2 bilayeredfilms show a lower transmittance of 76.1%. However, as-deposited ITO/TiO2 films show a lower resistivity(9.87×10-4 ?cm) than that of ITO single layer films. In addition, the work function of the ITO film is affected by the TiO2buffer layer, with the ITO/TiO2 films having a higher work-function (5.0 eV) than that of the ITO single layer films. Theexperimental results indicate that a 5-nm-thick TiO2 buffer layer on the ITO/TiO2 films results in better performancethan conventional ITO single layer films.

Daeil Kim

2013-01-01

265

Up-conversion luminescence application in Er3+: TiO2 thin film prepared by dip coating sol-gel route  

International Nuclear Information System (INIS)

Sol-gel derived nano-crystalline titanium dioxide films doped with 1 up to 5% Er3+ ions were prepared by dip coating sol-gel method. The coating sol was obtained by hydrolysis of Ti(OC4H9)4 in ethanol/HCI solution. The FT-Raman and the X-ray diffraction (XRD) were carried out to determine the crystal structure of the prepared samples. The morphology SEM and the cross-sectional of the film were used to characterize the microstructure and the thickness of the prepared film. It is shown that relative homogeneous, crack-free and transparent film was achieved via dipping process at 500 deg C. After the excitation with laser diode at wavelength 808 nm, visible (Vis) and infrared (IR) up-conversion emissions were evidenced in the thin film samples under investigation. The up-conversion was found to depend strongly on the Er3+ ion concentrations. The visible emission was found to be at 540, 560, 590 and 640 nm for thin film. They are attributed to intra-4f transition of Er3+ ions and assigned to the (2H11/2 + 4S3/2) and 4F9/2, which are populated through excited state absorption (ESA) for 808 nm excitation. (author)

2008-01-01

266

Quantitative Measurements of Photocatalytic CO-Oxidation as a Function of Light Intensity and Wavelength over TiO2 Nanotube Thin Films in mu-Reactors  

DEFF Research Database (Denmark)

Gas-phase photooxidation of CO over TiO2 catalysts (P25 and TiO2 nanotubes) in mu-reactors with quantitative product detection was used to study turnover as a function of illumination intensity over 4 orders of magnitude. Turnover was found to be of order 0.84 in illumination intensity. A CO photooxidation action spectrum was also recorded for TiO2 nanotubes. The action spectrum was used to calculate both the incident photon to product efficiency (IPPE) and the absorbed photon to product efficiency (APPE). The wavelength dependence of the IPPE was found to follow the absorption spectrum while the APPE was found to have a peak around 345 nm with a value of about 0.8%.

Vesborg, Peter Christian Kjærgaard; In, Su-il

2010-01-01

267

TiO2 films prepared by micro-plasma oxidation method for dye-sensitized solar cell  

International Nuclear Information System (INIS)

Nanocrystalline TiO2 films are widely investigated as the electrodes of dye-sensitized solar cell(s) with different preparation methods. In this paper, thin titanium dioxide films have been prepared on titanium plates by the micro-plasma oxidation method in the sulfuric acid solution. The thin TiO2 films were sensitized with a cis-RuL2(SCN)2.2H2O (L = cis-2,2'-bipyridine-4,4'-dicarboxylic acid) ruthenium complex and implemented into a dye-sensitized solar cell configuration. The influence of reaction current density (10, 15, 20, 25 and 30 A dm-2) on the structural and the surface morphology of the films was investigated by X-ray diffraction, scanning electron microscopy, atom force microscopy and X-ray photoelectricity spectroscopy. Impedance analysis for dye-sensitized solar cells was carried out by electrochemical impedance spectroscopy. The results show that the rise of current density leads to the increase in the amount of rutile and the thickness of the TiO2 film, which makes the TiO2 films have different photovoltages and photocurrents. The relatively higher photoelectricity properties were obtained in the TiO2 films prepared at a current density of 20 A dm-2. The open-circuit voltage and the short-circuit current are 605 mV and 165 ?A cm-2, respectively

2007-12-31

268

Real-time investigation on photocatalytic oxidation of gaseous methanol with nanocrystalline WO3–TiO2 composite films  

International Nuclear Information System (INIS)

Here we report on our investigation on photocatalytic oxidation (PCO) of gaseous methanol with WO3–TiO2 composite films. WO3 and WO3–TiO2 composite thin films were prepared by drop casting method. PCO of gaseous methanol and hydrogen generation process on platinum loaded WO3–TiO2 composite thin films in high vacuum were investigated using a home-made reactor with a six-channel quadrupole mass spectrometer at real-time scale under UVA (300–400 nm) light illumination. In the case of Pt loaded WO3 thin films, PCO of gaseous methanol proceeds through intermediates viz. formaldehyde, CO and finally to CO2 and H2. PCO of gaseous methanol occurs via direct hole transfer over Pt loaded WO3 thin films. On the other hand, PCO of gaseous methanol over Pt loaded WO3–TiO2 composite thin films proceeds with competitive direct and indirect hole transfer reactions. Our real-time analysis of gas phase photocatalysis realized the identification of direct and indirect hole transfer processes and the reaction intermediates thereof.

2012-03-01

269

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

270

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english In this work is investigated the optimal conditions for deposition of pure- phase anatase and rutile thin films prepared at low temperatures (less than 150ºC) 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 a (more) nalysis 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's noticeable a strong dependence of surface roughness with parameters studied.

Toku, H.; Pessoa, R.S.; Maciel, H.S.; Massi, M.; Mengui, U.A.

2010-09-01

271

Photodecomposition of Rhodamine B on TiO2/SiO2 thin films prepared by sol-gel method  

Science.gov (United States)

Glasses showing catalytic effect have been of much interest recently because the catalytic layer is very effective in reducing of pollutants. The use of these glasses may bring reduction in cleaning costs. There are several methods of preparation of TiO2 with good catalytic properties, but sol-gel technique offers an opportunity to enhance catalytic effect by precise optimization of the composition and microstructure of the layer. This study concerns optimization of the composition and preparation technology of catalytic layers based on SiO2-TiO2 system. Catalytic effect was studied using Rhodamine B as a sensor. UV-VIS and photoelectron spectroscopy were the main research tools used in this study.

Nocu?, M.; Kwa?ny, S.; Zontek, J.

2013-01-01

272

The photocatalytic activity of TiO2 thin film deposited on Al plate together with Cu(II) and Ag(I).  

UK PubMed Central (United Kingdom)

Cu (II) and Ag(I) together with TiO(2) powder were deposited on conducting support substrates to enhance the photocatalytic ability. The catalytic efficiency was tested by monitoring the photocatalytic degradation and detriment of methylene blue (MB) and bovine serum albumin (BSA). The conformational change of BSA induced by catalysts was also observed by circular dichroism spectroscopy.The antibacterial activities were studied by Escherichia coli. Both MB and BSA could be degraded more efficiently than pure TiO(2). After treatment with catalyst, the morphology of cells became twisted and rougher. Regular wrinkles were damaged and groove-like rift appeared on the surface. The fluorescence polarization has shown a significant decrease in membrane fluidity and the increase of permeability of cell membrane. Changes of the spectral profile of E. coli were observed, which suggested the damages of surface groups on the cell membrane.

Zhang T; Yao K; Guo Y

2011-12-01

273

Fabrication of TiO2 nanoparticles and films and their UV-VIS absorbance  

Science.gov (United States)

TiO2 nanoparticles have been synthesized by co-precipitation method with mechanical stirring in hydrothermal conditions. TiO2 film was fabricated on the top of a glass with spin-coating using the prepared TiO2 nanoparticles dissolved in a surfactant. The TiO2 film was fabricated to observe if TiO2 nanoparticles will still be kept in its phases as those of nanoparticles, and to further explore their properties for optical applications. Characterizations of the crystal structure, morphology and their optical absorption were performed by means of XRD, TEM, and UV-VIS spectrophotometer.

Widaryanti, Henyk Nur; Darminto

2013-09-01

274

A study on V+ ion-implanted TiO2 photocatalytic films  

International Nuclear Information System (INIS)

In order to improve photocatalytic property of TiO2 films, the films were implanted with 40 keV V+ ions to doses of 0.6 x l016, l x l016, 3 x l016 or 6 x l016 ions/cm2. Optical band gap of the V+ ion-implanted TiO2 films were measured by a spectrophotometer. The results show that the optical band gap of TiO2 films decreased with the increasing implantion dose. Methyl orange (MO) in aqueous solution was catalyzed by the ion-implanted TiO2 films under visible light. (authors)

2007-01-01

275

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)

[en] 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.

2012-01-01

276

Tailoring the wettability of nanocrystalline TiO2 films  

Science.gov (United States)

The water contact angle (WCA) of nanocrystalline TiO2 films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ˜156°, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ˜0°. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic-hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

Liang, Qiyu; Chen, Yan; Fan, Yuzun; Hu, Yong; Wu, Yuedong; Zhao, Ziqiang; Meng, Qingbo

2012-01-01

277

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

International Nuclear Information System (INIS)

[en] 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

278

Photoelectrocatalytic degradation of pentachlorophenol in aqueous solution using a TiO2 nanotube film electrode  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) nanotube film electrodes are fabricated by the anodic oxidation method. Scanning electron microscopy (SEM) showed that these tubes were well aligned and organized into high-density uniform arrays. XRD analysis showed the TiO2 nanotubes to be in the anatase crystal form. The TiO2 nanotube film electrode exhibited increased photoelectrocatalytic (PEC) capability compared to a traditional TiO2 film electrode fabricated using the anodizing method for pentachlorophenol (PCP) degradation in aqueous solution. The bias potential, pH value, and electrolyte concentration were shown to be important factors influencing the degradation of PCP by the PEC method using the TiO2 nanotube film electrode as the working electrode. - The characters and application influencing factors of the TiO2 nanotube film electrode fabricated by the anodic oxidation method were investigated.

2007-01-01

279

Atomic Layer Deposition of TiO2 on surface modified nanoporous low-k films.  

UK PubMed Central (United Kingdom)

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 analyse the damage induced by a plasma treatment on a nanoporous thin film.

Levrau E; Devloo-Casier K; Dendooven J; Ludwig K; Verdonck P; Meersschaut J; Baklanov MR; Detavernier C

2013-09-01

280

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

Scientific Electronic Library Online (English)

Full Text Available 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 ultraviolet component of the solar radiation is around 7%. Therefore, it is convenient to modify the TiO2 films crystalline structure for obtaining photocatalytical processes with (more) 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.

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

2011-03-01

 
 
 
 
281

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

282

Preparation and Characterization of Pure Rutile TiO2 Nanoparticles for Photo catalytic Study and Thin Films for Dye-Sensitized Solar Cells  

International Nuclear Information System (INIS)

Pure rutile-phase TiO2 (r-TiO2) was synthesized by a simple one pot experiment under hydrothermal condition using titanium (IV) n-butoxide as a Ti-precursor and HCl as a peptizer. The TiO2 products were characterized by XRD, TEM, ESCA, and BET surface area measurement. The r-TiO2 were rodlike in shape with average size of ? 61 x 32 nm at hydrothermal temperature of 220 degree C for 10 h. Hydrothermal treatment at longer reaction time increased the tendency of crystal growth and also decreased the BET surface area. The degradation of methylene blue was selected as a test reaction to confer the photocatalytic activity of as-obtained r-TiO2. The results showed a strong correlation between the structure evolution, particle size, and photocatalytic performance of r-TiO2. Furthermore, the r-TiO2-based solar cell was prepared for the photovoltaic characteristics study, and the best efficiency of ? 3.16% was obtained.

2011-01-01

283

Influence of porous morphology on optical dispersion properties of template free mesoporous titanium dioxide (TiO2) films  

International Nuclear Information System (INIS)

This paper focuses the influence of porous morphology on the microstructure and optical properties of TiO2 films prepared by different sol concentration and calcination temperatures. Mesoporous TiO2 thin films were prepared on the glass substrates by sol-gel dip coating technique using titanium (IV) isopropoxide. Porous morphology of the films can be regulated by chemical kinetics and is studied by scanning electron microscopy. The optical dispersion parameters such as refractive index (n), oscillator energy (Ed), and particle co-ordination number (Nc) of the mesoporous TiO2 films were studied using Swanepoel and Wemple-DiDomenico single oscillator models. The higher precursor concentration (0.06 M), films exhibit high porosity and refractive index, which are modified under calcination treatment. Calcinated films of low metal precursor concentration (0.03 M) possess higher particle co-ordination number (Nc = 5.05) than that of 0.06 M films (Nc = 4.90) due to calcination at 400 deg. C. The lattice dielectric constant (E?) of mesoporous TiO2 films was determined by using Spintzer model. Urbach energy of the mesoporous films has been estimated for both concentration and the analysis revealed the strong dependence of Urbach energy on porous morphology. The influence of porous morphology on the optical dispersion properties also has been explained briefly in this paper.

2008-01-30

284

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

Science.gov (United States)

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.

Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

2012-12-01

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

A new precursor for the preparation of nanocrystalline TiO2 films and their photocatalytic properties.  

UK PubMed Central (United Kingdom)

In this work, we present a new precursor for the preparation of thin and transparent nanocrystalline TiO2 films, which involves the use of Titanium(IV) bis(ammonium lactato) dihydroxide as Ti(IV) source and Triton X-100 as surfactant template. The films were heated at various temperatures in order to optimize their nanostructure and their photocatalytic activity. The morphology and the nanostructure of the films were characterized by SEM and AFM. Crystallinity of the films was examined by XRD and their light absorption with UV-Vis spectroscopy. The photocatalytic activity of the films was investigated by using an azo dye: Basic Blue 41. Excitation of the samples was made by low intensity black light tubes emitting in the Near-UV. The photodegradation of the dye was studied as a function of the quality of the deposited TiO2 films and the calcination temperature in comparison with similar films made by standard procedures.

Pelentridou K; Stathatos E; Lianos P; Drakopoulos V

2010-09-01

287

Effects of Morphology of Anatase TiO2 Nanotube Films on Photocatalytic Activity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Five groups of TiO2 nanotube array films with different inner diameters and five groups with different tube lengths were fabricated on titanium by anodization. Morphology was analyzed by scanning electron microscope. The photocatalytic activity of the TiO2 nanotube films cry...

CUI Qiang, FENG Bo, CHEN Wei, WANG Jian-Xin, LU Xiong, WENG Jie

288

Photocatalytic Properties of TiO2 Films Deposited by Reactive Sputtering in Mid-Frequency Mode with Dual Cathodes  

Science.gov (United States)

Titanium dioxide (TiO2) films were deposited on unheated nonalkali glass substrates by reactive midfrequency (mf) magnetron sputtering using dual cathodes with two Ti metal targets. In order to maintain the very high deposition rate, the depositions were successfully carried out stably in the “transition region” between the metallic and reactive (oxide) sputter modes using plasma control units (PCU). Very high-rate depositions of 12-70 nm/min were successfully achieved in the deposition of TiO2 films throughout the whole “transition region”. The as-deposited films deposited in the “oxide mode” had a polycrystalline anatase structure and exhibited both photoinduced hydrophilicity and photodecomposition of acetaldehyde. Whereas, all the as-deposited TiO2 films deposited in the “transition region” had amorphous structure, which did not exhibit photocatalytic activity. Such amorphous films deposited in the transition region were crystallized by postannealing in air at 200°C or 300°C and were then shown to have photocatalytic activity. Very thin TiO2 films with a thickness of 25 nm deposited in the transition region and postannealed at 300°C exhibited photoinduced hydrophilicity, whereas there was a clear thickness dependence of photodecomposition and the rather thick films of 300 nm exhibited pronounced photodecomposition.

Ohno, Shingo; Sato, Daisuke; Kon, Masato; Sato, Yasushi; Yoshikawa, Masato; Frach, Peter; Shigesato, Yuzo

2004-12-01

289

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 diffractometry, and scanning electron microscopy to reveal the structural and morphological differences. In addition, the photocatalytic properties of these films were investigated by degrading methyl orange (MO) under UV irradiation. After 500Co calcination, the microstructure of MC-TiO2 film without Ag addition exhibited a microstructure, while significant sintering effect was noticed with Ag additions and the films exhibited a porous microstructure. Nanostructure anatase-phase TiO2 can be observed with respect to the sharpening of XRD diffraction peaks. The photodegradation of porous TiO2 deposited with 5×10−4 mol Ag exhibited the best photocatalytic efficiency, where 69% methyl orange can be decomposed after UV exposure for 1 hour.

Mojtaba Nasr-Esfahani; Mohammad Hossein Habibi

2008-01-01

290

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

Directory of Open Access Journals (Sweden)

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

2007-01-01

291

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

2010-11-10

292

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

UK PubMed Central (United Kingdom)

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.

Clavel G; Marichy C; Willinger MG; Ravaine S; Zitoun D; Pinna N

2010-12-01

293

p-NITROPHENOL PHOTOCATALYSIS ON NANOSTRUCTURED TiO2 FILMS  

Directory of Open Access Journals (Sweden)

Full Text Available 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 reaction system with recirculation in presence of UV light provided by a solar simulator. It was found that both nanostructures degrade the organic matter efficiently following the Langmuir-Hinshelwood kinetic model; supported nanoparticles have a maximum reaction rate of 3.3 times faster than the thin film, the nanotubes are 2.5 times faster than the supported nanoparticles, and nanoparticles in suspension are 1.3 times faster than the nanotubes.

Damelis López; Walter Lozada; Sergio Blanco; Gabriela Durán; Lorean Madriz; Ronald Vargas

2011-01-01

294

PHOTOCATALYTIC TIO2 FILMS AND MEMBRANES FOR THE DEVELOPMENT OF EFFICIENT WASTEWATER TREATMENT AND REUSE SYSTEMS  

Science.gov (United States)

In order to develop efficient photocatalytic TiO2 films and membranes for application in water and wastewater treatment and reuse systems, there is a great need to tailor-design the structural properties of TiO2 material and enhance its photocatalytic activity. Through...

295

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

Science.gov (United States)

Degradation of dimethoate under UV irradiation using TiO(2)/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 TiO(2) 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. PMID:21880417

Priya, D Neela; Modak, Jayant M; Trebše, Polonca; Zabar, Romina; Raichur, Ashok M

2011-08-16

296

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

UK PubMed Central (United Kingdom)

Degradation of dimethoate under UV irradiation using TiO(2)/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 TiO(2) 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.

Priya DN; Modak JM; Trebše P; Zabar R; Raichur AM

2011-11-01

297

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

Directory of Open Access Journals (Sweden)

Full Text Available Amorphous TiO2 thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at 250?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.

J. C. Johnson; S. P. Ahrenkiel; P. Dutta; V. R. Bommisetty

2009-01-01

298

Low temperature deposition and characterization of TiO2 photocatalytic film through cold spray  

International Nuclear Information System (INIS)

Cold spray was employed as a novel low temperature approach to deposit titanium dioxide (TiO2) photocatalytic film. The film microstructure was characterized using X-ray diffraction and scanning electron microscopy. The photocatalytic performance was examined through acetaldehyde degradation under ultraviolet illumination. Results showed that TiO2 film was successfully deposited on substrate surface through cold spray. The film thickness reached up to 15 ?m. The film presented a rough surface and porous structure. Owing to the low temperature of spray powder, no phase and particle size changes occurred to TiO2 during deposition. It was found that the cold-sprayed TiO2 film was active for photodegradation of acetaldehyde

2008-04-30

299

GISAXS investigation of TiO2 nanoparticles in PS-b-PEO block-copolymer films  

International Nuclear Information System (INIS)

Ordered 2D-arrays of TiO2 nanoparticles were synthesised by a poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) block-copolymer templated sol-gel process within a thin polymer film. The order within the filled polymer films was found to depend on the sol-gel content during synthesis. Grazing incidence small angle X-ray scattering and scanning electron microscopy imaging proved that well-ordered structures were created over large areas of the thin hybrid film.

2005-02-28

300

Preparation and characterization of polyvinyl alcohol films containing TiO2 nanoparticles  

International Nuclear Information System (INIS)

[en] 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)

2007-01-01

 
 
 
 
301

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

Directory of Open Access Journals (Sweden)

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

2012-01-01

302

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

Directory of Open Access Journals (Sweden)

Full Text Available Polymer electrolytes as nanostructured materials are very attractive components for batteries and opto-electronic devices. (PEO)8ZnCl2 polymer electrolytes were prepared from PEO and ZnCl2. The nanocomposites (PEO)8ZnCl2/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.

Aleksandra Turkovi?; Pavo Dub?ek; Krunoslav Jurai?; Antun Drašner; Sigrid Bernstorff

2010-01-01

303

Effects of Morphology of Anatase TiO2 Nanotube Films on Photocatalytic Activity  

Directory of Open Access Journals (Sweden)

Full Text Available Five groups of TiO2 nanotube array films with different inner diameters and five groups with different tube lengths were fabricated on titanium by anodization. Morphology was analyzed by scanning electron microscope. The photocatalytic activity of the TiO2 nanotube films crystallized into anatase, was evaluated by the decolorization of methyl orange in aqueous solution under UV light irradiation. The effects of the nanotube diameter and length on the photocatalytic activity were investigated. The reusability of photocatalyst was evaluated through repeated photocatalytic reaction experiment. Results suggest that the TiO2 nanotube films with the diameter of 100nm exhibit the best photocatalytic activity to the degradation of methyl orange, and the length of nanotube has little effect on the photocatalytic activity. Repeated photocatalytic reaction experiment shows that the TiO2 nanotube films have excellent resuability as photocatalyst.

CUI Qiang, FENG Bo, CHEN Wei, WANG Jian-Xin, LU Xiong, WENG Jie

2010-01-01

304

Time-resolved indirect nanoplasmonic sensing spectroscopy of dye molecule interactions with dense and mesoporous TiO2 films.  

UK PubMed Central (United Kingdom)

Indirect nanoplasmonic sensing (INPS) is an experimental platform exploiting localized surface plasmon resonance (LSPR) detection of processes in nanomaterials, molecular assemblies, and films at the nanoscale. Here we have for the first time applied INPS to study dye molecule adsorption/impregnation of two types of TiO(2) materials: thick (10 ?m) mesoporous films of the kind used as photoanode in dye-sensitized solar cells (DSCs), with particle/pore size in the range of 20 nm, and thin (12-70 nm), dense, and flat films. For the thick-film experiments plasmonic Au nanoparticles were placed at the hidden, internal interface between the sensor surface and the mesoporous TiO(2). This approach provides a unique opportunity to selectively follow dye adsorption locally in the hidden interface region inside the material and inspires a generic and new type of nanoplasmonic hidden interface spectroscopy. The specific DSC measurement revealed a time constant of thousands of seconds before the dye impregnation front (the diffusion front) reaches the hidden interface. In contrast, dye adsorption on the dense, thin TiO(2) films exhibited much faster, Langmuir-like monolayer formation kinetics with saturation on a time scale of order 100 s. This new type of INPS measurement provides a powerful tool to measure and optimize dye impregnation kinetics of DSCs and, from a more general point of view, offers a generic experimental platform to measure adsorption/desorption and diffusion phenomena in solid and mesoporous systems and at internal hidden interfaces.

Gusak V; Heiniger LP; Graetzel M; Langhammer C; Kasemo B

2012-05-01

305

Composite films of polycations and TiO2 nanoparticles with photoinduced superhydrophilicity.  

Science.gov (United States)

We apply herein the reactive layer-by-layer (LBL) spray deposition of a polycation (polyethyleneimine, PEI) and a water soluble initiator of titanium dioxide [Ti(IV) bis(ammoniumlactato)dihydroxide, TiBisLac] to produce thin hybrid films containing PEI and nearly monodisperse TiO(2) anatase nanoparticles. The thickness of these coatings can be finely adjusted by either changing the number of deposition steps or the TiBisLac concentration. These films display intense absorption in the UV range and nearly full transparency above 365 nm and they also display photoinduced superhydrophilicity. These coatings can be produced either by reactive LBL spray deposition or reactive LBL dipping and may offer a wide range of applications from biology, as antibacterial coatings, to photoactive materials. PMID:18514216

Laugel, Nicolas; Hemmerlé, Joseph; Ladhari, Nadia; Arntz, Youri; Gonthier, Eric; Haikel, Youssef; Voegel, Jean-Claude; Schaaf, Pierre; Ball, Vincent

2008-05-16

306

Composite films of polycations and TiO2 nanoparticles with photoinduced superhydrophilicity.  

UK PubMed Central (United Kingdom)

We apply herein the reactive layer-by-layer (LBL) spray deposition of a polycation (polyethyleneimine, PEI) and a water soluble initiator of titanium dioxide [Ti(IV) bis(ammoniumlactato)dihydroxide, TiBisLac] to produce thin hybrid films containing PEI and nearly monodisperse TiO(2) anatase nanoparticles. The thickness of these coatings can be finely adjusted by either changing the number of deposition steps or the TiBisLac concentration. These films display intense absorption in the UV range and nearly full transparency above 365 nm and they also display photoinduced superhydrophilicity. These coatings can be produced either by reactive LBL spray deposition or reactive LBL dipping and may offer a wide range of applications from biology, as antibacterial coatings, to photoactive materials.

Laugel N; Hemmerlé J; Ladhari N; Arntz Y; Gonthier E; Haikel Y; Voegel JC; Schaaf P; Ball V

2008-08-01

307

Reactive sputtering TiO2 films for surface coating of poly(dimethylsiloxane)  

International Nuclear Information System (INIS)

[en] Titanium dioxide (TiO2) films were prepared on poly(dimethylsiloxane) (PDMS) substrate by direct current (DC) reactive sputtering to change surface physical properties of PDMS. The effects of the changes were investigated by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) analysis, water contact angle measurements and protein adsorption tests. Improved wettability and reduced adsorption properties were observed on PDMS surface coated TiO2 films

2006-01-15

308

Passivation of TiO2 by ultra-thin Al-oxide  

International Nuclear Information System (INIS)

[en] The passivation of sol-gel TiO2 by ultra-thin layers of Al-oxide has been investigated using transient and spectral photovoltage (PV) techniques. The ultra-thin layers of Al-oxide were prepared by the ion-layer gas reaction (ILGAR) technique and modified by thermal treatments in air, vacuum or Ar/H2S atmosphere. The samples where characterized by elastic recoil detection analysis (ERDA), X-ray photoelectron spectroscopy (XPS), and contact potential difference (CPD) technique. Without an Al-oxide surface layer, electronic states in the forbidden gap of TiO2 are formed during thermal treatments in vacuum and Ar/H2S. The trap density is strongly reduced at the TiO2/Al-oxide interface. The formation of electronic defects is prevented by a closed ultra-thin layer of Al-oxide

2005-02-15

309

Method for preparing TiO2-HA biological medical nanometer structured film  

UK PubMed Central (United Kingdom)

The invention discloses a making method of TiO2-HA biological medical nanostructure film in biological stock technique domain, wherein the ratio of TiO2 and HA is between 1í -9 and 9í 1 The ratio of Ca and P is between 1.6í 1 and 1.7í 1 which comprises the following steps: cleaning, drying and fixing the medical implant base material fixing the sputtering target material drying the vacuum chamber sputtering cleaning target material surface passing the oxygen after steady sputtering cleaning moving baffle turning substrate sputtering Ti/HA and Ti target in turn sedimentating the TiO2-HA composite film fetching the sample out of the vacuum chamber after sputtering. The invention adapts reaction magnetic sputtering technique to control the film component and particle dimension by adjusting the sputtering parameter and adding TiO2 ceramic component.

ZHONG XIAOXIA WU

310

Fabrication and hydrogen sensing properties of interlinked ribbon-like TiO2 films.  

UK PubMed Central (United Kingdom)

Interlinked ribbon-like TiO2 films were prepared by micro-arc oxidation (MAO) process and subsequent chemical-treatment of titanium substrate. The chemical-treatment included two steps: firstly, alkali treatment was performed on the surface of the porous TiO2 films, and then the samples were ion-exchanged in acid aqueous solution. The phase and microstructure of the samples were characterized by XRD, FE-SEM and TEM. It is found that ribbon-like sodium titanate is formed by alkali treatment, and its morphology remains unchanged after acid-treatment. However, the phase compositions of the samples surface change into TiO2 (MAOC-TiO2) after heat-treatment above 500 degrees C. The hydrogen sensing properties at low concentrations were investigated. The result shows that such ribbon-like TiO2 films present high sensing properties at a low temperature.

Ren F; Huang L; Ling Y; Shen S; Feng J

2010-11-01

311

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 substrates. All films made by solution processing techniques are coated on the transparent substrate (glass) with a conducting film ITO. The efficiency of this solar cell is compared with the conventional device using Al as electrode.

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

2009-01-01

312

Characterization of TiO2 nanoparticles in Langmuir-Blodgett films.  

Science.gov (United States)

In this work we have synthesized TiO2 nanoparticles, using either a sol-gel base catalysed process in the interior of CTAB reversed micelles (TiO2 CTAB sol), or the neutralization of a TiO2/H2SO4 solution in the interior of AOT reversed micelles. From the absorption and emission data of the TiO2 nanoparticles it is possible to conclude that in the sol-gel route there remains alkoxide groups in the structure, originating transitions lower than the energy gap of TiO2 semiconductor. These transitions disappear in the neutralization procedure, where the alkoxide groups are absent in the structure. We have assigned the observed indirect and direct optical transitions according to the anatase band structure. TiO2 Langmuir-Blodgett (LB) films were prepared either by direct deposition of titanium isopropoxide or by deposition of the TiO2 CTAB sol. These films showed photoluminescence, which was attributed to band-gap emission and to surface recombination of defect states. PMID:16791503

Coutinho, Paulo J G; Barbosa, M Teresa C M

2006-05-12

313

Characterization of TiO2 nanoparticles in Langmuir-Blodgett films.  

UK PubMed Central (United Kingdom)

In this work we have synthesized TiO2 nanoparticles, using either a sol-gel base catalysed process in the interior of CTAB reversed micelles (TiO2 CTAB sol), or the neutralization of a TiO2/H2SO4 solution in the interior of AOT reversed micelles. From the absorption and emission data of the TiO2 nanoparticles it is possible to conclude that in the sol-gel route there remains alkoxide groups in the structure, originating transitions lower than the energy gap of TiO2 semiconductor. These transitions disappear in the neutralization procedure, where the alkoxide groups are absent in the structure. We have assigned the observed indirect and direct optical transitions according to the anatase band structure. TiO2 Langmuir-Blodgett (LB) films were prepared either by direct deposition of titanium isopropoxide or by deposition of the TiO2 CTAB sol. These films showed photoluminescence, which was attributed to band-gap emission and to surface recombination of defect states.

Coutinho PJ; Barbosa MT

2006-05-01

314

Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis  

International Nuclear Information System (INIS)

Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H2SO4/Eu(NO3)3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H2SO4/Eu(NO3)3 electrolyte, were increased compared to that of the anodic TiO2 film prepared in H2SO4 solution. The absorbance response of N-Eu titania film shows a higher adsorption onset toward visible light region, and the incorporated N and Eu ions during anodization as a dopant in the anodic TiO2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO2 film were 60.7% and 90.1% for the N-Eu doped titania film. The improvement of the photocatalytic activity was ascribed to the synergistic effects of the surface enlargement and the new electronic state of the TiO2 band gap by N and Eu co-doping.

2011-05-31

315

Graphene incorporated nanocrystalline TiO2 films for the photocathodic protection of 304 stainless steel  

Science.gov (United States)

Composite films of TiO2 and graphene (GR) were prepared on 304 stainless steel (304SS) by the sol–gel method and heat treatment. The morphology, crystalline phase, and composition of the GR/TiO2 films were characterized systematically by X-ray diffraction, Raman spectroscopy and scanning electron microscopy, respectively. The photocathodic protection performances of the composite film under illumination and dark conditions in 3.0% NaCl solution were evaluated through the electrochemical measurements. It is indicated that the incorporation of GR in TiO2 film can improve effectively the photocathodic protection effect for 304SS under the UV illumination. Compared to 350 mV of pure TiO2 film, the electrode potentials can be negatively shifted to about ?600 mV under UV light irradiation by incorporating GR into TiO2 films. At the same time, a 14-fold photocurrent density can be obtained for the GR/TiO2 film. This indicates that GR can play an excellent enhancing effect on the photogenerated cathodic protection of TiO2 films.

Guo, Xiangqin; Liu, Wei; Cao, Lixin; Su, Ge; Xu, Hongmei; Liu, Binhao

2013-10-01

316

Corrosion behavior of anodic oxidized TiO2 film in seawater  

Science.gov (United States)

TiO2 films were formed on metallic titanium substrates by the anodic oxidation method in H2SO4 solution under the 80V D.C.. Phase component and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Water contact angles on titanium oxide film surface were measured under both dark and sunlight illumination conditions. Corrosion tests were carried out in seawater under different illumination conditions by electrochemistry impedance spectrum (EIS) and polarization curves. The result showed that the TiO2 film prepared by the anodic oxidation method was anatase with a uniform structure and without obvious pores or cracks on its surface. The average water contact angle of the film was 116.4° in dark, in contrast to an angle of 42.7° under the UV illumination for 2 hours, which demonstrates good hydrophobic property. The anti-corrosion behavior of the TiO2 film was declining with the extended immersion time. Under dark conditions, however, the hydrophobic TiO2 film retarded the water infiltrating into the substrate. The impedance changed slowly and the corrosion current density was 2 orders of magnitude lower than that with the film illuminated by sunlight. All of those mentioned above indicate that the TiO2 film possesses much better performance under dark condition, and it can be applied as an engineering material under dark seawater environment.

Wang, Min; Wang, Wei; He, Benlin; Sun, Mingliang; Yin, Yansheng; Liu, Lan; Zou, Wuyuan; Xu, Xuefei

2010-12-01

317

Sensitizing of Sm3+ fluorescence by silver dopant in the TiO2 films  

Science.gov (United States)

Composite material based on a TiO2 matrix doped with Sm3+ ions and co-doped with silver was investigated. Samarium ions together with nano- and micro-aggregates of silver were incorporated into the titanium alkoxide during the sol-gel process. Samarium ions were excited either directly ( ? exc = 488 nm) or through the TiO2 host ( ? exc = 355 nm). It was revealed that samarium fluorescence ( ? exc = 488 nm) in gelled TiO2 films is enhanced by up to 20 times in the vicinity of silver inclusions. Sensitizing and plasmonic mechanisms of enhancement in Sm3+ fluorescence are discussed.

Dolgov, Leonid; Kiisk, Valter; Reedo, Valter; Pikker, Siim; Sildos, Ilmo; Kikas, Jaak

2011-04-01

318

Protein Adsorption on Nanocrystalline TiO(2) Films:? An Immobilization Strategy for Bioanalytical Devices.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have investigated the use of optically transparent, nanoporous TiO(2) films as substrates for protein immobilization. Immobilization on such films may be readily achieved from aqueous solutions at 4 °C. The nanoporous structure of the film greatly enhances the active surface area available for pr...

Topoglidis, E; Cass, AE; Gilardi, G; Sadeghi, S; Beaumont, N; Durrant, JR

319

Anatase and rutile TiO2 films deposited by arc-free deep oscillation magnetron sputtering  

Science.gov (United States)

Phase control of TiO2 films at low deposition temperatures is important for many applications. In this study, nanocrystalline TiO2 films were synthesized on glass and steel substrates in a balanced magnetron sputtering system using the new deep oscillation magnetron sputtering (DOMS) and pulsed dc magnetron sputtering (PDCMS) techniques. A virtually arc-free high-power pulsed magnetron sputtering process for TiO2 reactive sputtering was observed for DOMS. No external substrate bias and heating were used for the depositions. For the DOMS TiO2 depositions, different peak target currents (powers) were used. The crystal phase and microstructure of the TiO2 films were characterized and compared. It was found that the TiO2 films deposited by PDCMS exhibited a complete anatase phase. The TiO2 films deposited by DOMS at a low target peak current (e.g. 50 A) also contained mainly the anatase phase. Nevertheless, an increase in the peak target current for the DOMS deposition promoted the formation of the rutile phase, increased the density and decreased the grain size of the TiO2 films. A complete rutile phase was obtained for the TiO2 film deposited by DOMS at a high target peak current (200 A). The mechanical and optical properties of the anatase and rutile TiO2 films were also studied and compared.

Lin, Jianliang; Wang, Bo; Sproul, William D.; Ou, Yixiang; Dahan, Isaac

2013-02-01

320

Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2  

International Nuclear Information System (INIS)

[en] 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.

1300-01-00

 
 
 
 
321

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

International Nuclear Information System (INIS)

[en] 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

322

Bioactive TiO2 fiber films prepared by electrospinning method.  

UK PubMed Central (United Kingdom)

Electrospining method was used to prepare bioactive TiO(2) fibers films in this study. The acetic acid/ethanol/tetrabutyl titanate/polyvinylpyrrolidone (PVP) solvent system was used as precursor for the electrospining. The TiO(2) fiber structures (including its fiber diameter, morphology, and phase composition) could be controlled by changing feeding rate, PVP concentration and sinter temperature. The fiber films were subjected to simulated body fluid soaking experiments and MG63 cells culture experiments to study their bioactivity. According to the X-ray diffraction and MTT assay results, the fiber containing with anatase showed better apatite formation ability than that without anatase at the early stage, while cell proliferated on anatase-rutile TiO(2) fiber was better than that on other samples (p < 0.05).Some string beads in the fiber were beneficial for apatite formation, while the cell proliferated best on the fiber film without string beads (p < 0.05). The fiber with a diameter of 200 nm had the best apatite formation ability and osteoblast compatibility (p < 0.05). The results showed that the TiO(2) fiber film structure had great influence on its bioactivity. It indicated that the electronspining method is an effective way to prepare bioactive titania fiber films, and it is possible to control the structure of the films in the spinning process to optimize the bioactivity of TiO(2) fiber.

Chen SJ; Yu HY; Yang BC

2013-01-01

323

Effect of electrolysis conditions on photocatalytic activities of the anodized TiO2 films  

International Nuclear Information System (INIS)

Photocatalytic activities of anodized TiO2 films for decomposition of gaseous acetaldehyde were investigated. The anodized TiO2 films were fabricated by galvanostatic anodization in a mixed electrolyte composed of H2SO4, H3PO4, and H2O2. Pre-nitridation treatment effectively enhanced the photocatalytic activity of the anodized TiO2 films. The electrolysis parameters such as anodization time, current density, electrolyte temperature, and electrolyte composition significantly affected the photocatalytic activity of the anodized TiO2 films. The improvement of photocatalytic activity of the anodized films is attributed to increase in surface areas of the anodized specimens. - Graphical abstract: The effect of concentration of H3PO4 on the photocatalytic activity of the anodized TiO2 films was investigated. The pre-nitrided titanium plates were anodized in electrolyte of 1.5 M H3PO4 and 0.3 M H2O2 with varying H3PO4 concentration in the range from 0 to 0.5 M. The highest photocatalytic activity was obtained at H3PO4 concentration of 0.1 M.

2007-01-01

324

Polyvinyl pyrrolidone aided preparation of TiO2 films used in flexible dye-sensitized solar cells  

International Nuclear Information System (INIS)

Highlights: · Polyvinyl pyrrolidone (PVP) is used to low temperature prepare TiO2 film in flexible DSSC. · PVP improves TiO2 dispersion, adherence to flexible substrate and dye adsorption. · Ultraviolet light irradiation improve the surface state of TiO2 film. · Resultant flexible DSSC achieves a light-to-electric conversion efficiency of 3.02%. - Abstract: Polyvinyl pyrrolidone (PVP) is introduced to low temperature preparation of a good quality TiO2 film used in flexible dye-sensitized solar cells (DSSCs). The samples are characterized by scanning electron microscopy and UV-vis absorption spectra, the photovoltaic performance of the DSSC is measured. It is found that PVP can improve the dispersion of TiO2 particles and the adherence of TiO2 particles to flexible substrate, as well as the adsorption of sensitized dye to TiO2 film. Additionally, ultraviolet light irradiation can eliminate organics remained on the surface the TiO2 film and improve the surface state of TiO2 film. Under an optimal condition, a flexible DSSC using TiO2 film doped PVP and UV irradiation treated achieves a light-to-electric energy conversion efficiency of 3.02% under irradiation with a simulate solar light intensity of 100 mW cm-2.

2011-08-30

325

Dye-Sensitized Nanostructured TiO2 Film Based Photoconductor  

CERN Multimedia

Grooves were etched in a conductive layer of a conductive, transparent glass, and a nanoporous TiO2 film was deposited on both the conductive and nonconductive area. The width of the grooves was 100 $\\mu$m and 150 $\\mu$m. A transparent TiO2 film was dye-sensitized, covered with an electrolyte, and sandwiched with a cover glass. The conductivity of the dye-sensitized TiO2 film permeated with electrolyte was studied in the dark and under illumination, and was observed to be dependent on light intensity, wavelength and applied voltage. This study shows that dye-sensitized nanoporous films can be used as a wavelength dependent photoconductor.

Kallioinen, Jani; Paraoanu, G S; Korppi-Tommola, Jouko

2008-01-01

326

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

2013-02-26

327

Robust superamphiphobic film from electrospun TiO2 nanostructures.  

UK PubMed Central (United Kingdom)

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.

Ganesh VA; Dinachali SS; Nair AS; Ramakrishna S

2013-03-01

328

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

2010-01-01

329

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

330

Influence of auxiliary plasma source on properties of photoactive TiO2 films by MePIII and D  

International Nuclear Information System (INIS)

For several years, TiO2 is receiving increasing scientific attention as one of the most promising photo catalysts with a huge potential for solving several different types of environmental problems. While TiO2 powders and nanoparticles are well known and widely used, thin film surfaces are less investigated but still highly desired for applications. For TiO2 polymorphs, anatase powder is reported to be a more potent photo catalyst than rutile. Metal plasma immersion ion implantation and deposition is employed to form titanium oxide films at room temperature. By applying high voltage pulses of up to 5 kV at a duty cycle of 30%, polycrystalline films could be obtained. Additionally, an RF plasma source was used to increase the ionisation of the background oxygen gas at different flow rates, thus enhancing the ion bombardment of the surface. AFM, SEM, XRD and surface energy measurements show that by employing the auxiliary RF plasma source, a lower oxygen gas flux is compensated by increasing the oxygen content compared to the case without auxiliary plasma.

2010-01-01

331

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

International Nuclear Information System (INIS)

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.

2012-12-10

332

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

Science.gov (United States)

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).

Sério, S.; Melo Jorge, M. E.; Nunes, Y.; Barradas, N. P.; Alves, E.; Munnik, F.

2012-02-01

333

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

International Nuclear Information System (INIS)

[en] 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

334

Photo-rechargeability of TiO2 film electrodes prepared by pulsed laser deposition  

Energy Technology Data Exchange (ETDEWEB)

The film electrodes of TiO2, which have two functions of opto-electric conversion and storage of electrochemical energy, were prepared by pulsed laser deposition. To investigate the relationship between the photo-rechargeability and the surface structure, the TiO2 film electrodes with different surface morphology were prepared by changing the inert gas pressure during the deposition. The photo-charged quantity was found to be proportional to the third power of the rms of surface roughness. The results suggest that not only the surface but also the interstices between crystal grains near the surface contribute to the photo-charging with low photo-emf.

Usui, Hiroyuki; Miyamoto, Ousuke; Nomiyama, Teruaki; Horie, Yuji; Miyazaki, Tomoyuki [Department of Electrical and Electronics Engineering, Kagoshima University, Kagoshima 890-0065 (Japan)

2005-02-15

335

A new precursor for the preparation of nanocrystalline TiO2 films and their photocatalytic properties.  

Science.gov (United States)

In this work, we present a new precursor for the preparation of thin and transparent nanocrystalline TiO2 films, which involves the use of Titanium(IV) bis(ammonium lactato) dihydroxide as Ti(IV) source and Triton X-100 as surfactant template. The films were heated at various temperatures in order to optimize their nanostructure and their photocatalytic activity. The morphology and the nanostructure of the films were characterized by SEM and AFM. Crystallinity of the films was examined by XRD and their light absorption with UV-Vis spectroscopy. The photocatalytic activity of the films was investigated by using an azo dye: Basic Blue 41. Excitation of the samples was made by low intensity black light tubes emitting in the Near-UV. The photodegradation of the dye was studied as a function of the quality of the deposited TiO2 films and the calcination temperature in comparison with similar films made by standard procedures. PMID:21133154

Pelentridou, Katerina; Stathatos, Elias; Lianos, Panagiotis; Drakopoulos, Vassilios

2010-09-01

336

Investigation of thermal diffusivity of nano-structured TiO2 films  

International Nuclear Information System (INIS)

We investigate the thermal diffusivity of nano-structured TiO2 and TiO2 with 3% ZnFe2O4 ceramic films (nm films) sputtered on a cut Si substrates by using the Mirage effect method. Two series of films are prepared by the magneto-rf-spurt method. The investigation results show that: The thermal diffusivity of nano-structured film depends on the thickness of film and the annealing temperature. The thicker the film, the lower thermal diffusivity of the sample is. The value of thermal diffusivity increases with the increasing of the annealing temperature. It means that the thermal diffusivity depends on the phase structure of the film. The detail results, analyses and discussions will be presented in this paper.

2003-03-27

337

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

338

Epitaxial growth of tin oxide films on (0 0 1) TiO2 substrates by KrF and XeCl excimer laser annealing  

International Nuclear Information System (INIS)

Epitaxial SnO2 thin films were prepared by excimer laser annealing of amorphous SnO2 films on a (0 0 1) TiO2 substrate. The amorphous SnO2 film was prepared by a metal organic deposition (MOD) using di-n-butylbis (2,4-pentanedionate) tin at 300 deg. C. When using a KrF excimer laser with fluence of 50 to 150 mJ/cm2, polycrystalline SnO2 films were formed on (0 0 1) TiO2 substrate at 25 deg. C. At fluences of 200 and 250 mJ/cm2 (0 0 2) oriented SnO2 films were obtained. When using a XeCl laser with fluences of 150 and 200 mJ/cm2, the (0 0 2) oriented SnO2 films were obtained. Using the XRD ? scanning measurement, it was found that oriented SnO2 films were epitaxially grown on the (0 0 1) TiO2 substrate. The formation of the epitaxial SnO2 on the (0 0 1) TiO2 substrate was found to depend on the pre-irradiated amorphous SnO2 film thickness, laser fluence and laser wavelength.

2005-07-30

339

Preparation and microstructure properties of Al-doped TiO2-SiO2 gel-glass film  

International Nuclear Information System (INIS)

Al-doped TiO2-SiO2 gel-glass thin films on silicon wafers were prepared using a sol-gel method combined with a multi-layer spin coating technique. The precursor to the glass films was obtained by introducing aluminium nitrate with ethanol solution into the hydrolysis system of tetraethylorthosilicate as a dopant. X-ray photoelectron spectroscopy (XPS) depth profiling analysis of the glass films showed an excellent homogeneity of elemental composition. Titanium ions were indicated to exist in Si-O-Ti hetero-condensation forms. The microstructure of the film was investigated using an atomic force microscope across the crater created by Ar+ beam sputtering. The thickness and the refractive index of the film were estimated by means of the reflect spectra measurement.

2006-12-05

340

The preparation of TiO(2) thick film anodes for photoelectrochemical solar cells  

Energy Technology Data Exchange (ETDEWEB)

The use of thick film screen printing technology was investigated as a method of fabricating inexpensive TiO(2) anodes for applications in photoelectrochemical (PEC) solar cells. The thick film pastes were prepared from TiO(2) powders of both anatase and rutile structures, combined with varying amounts of a glass binder (0-25%) and dispersed in a liquid organic vehicle. The films were screen-printed and fired on metallized alumina substrates. The as-fired films were then thermally reduced in NH(3) to obtain a film resistivity of approximately 10 Ohm-cm. It was found that the use of a glass binder in these films resulted in poor PEC behaviour. However, good film adhesion can be achieved by using fritless anatase-based thick films and making use of the enhancement of the sintering process due to the anatase-rutile phase transformation during firing of these films at temperatures greater than 800 degr. C. This investigation has demonstrated the potential use of thick film technology as a practical, low cost method for the fabrication of TiO(2) photoanodes in PEC solar cells.

Blaauw, C. (Bell-Northern Research, Ottawa, Canada); Naguib, H.M.; Ahmad, A.; Ahmed, S.M.

1982-12-01

 
 
 
 
341

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

342

Investigations on TIO2 and AG based single and multilayer films for window glazings  

Directory of Open Access Journals (Sweden)

Full Text Available In this investigation, TiO2 and Ag based single and multilayer-films were deposited on microscope glass slides with varying individual layer thicknesses by radio-frequency reactive magnetron sputtering. Prior to multilayer development, single layers of Ag and TiO2 were deposited and characterized. All the films were prepared at an elevated pressure of 3 Pa at room temperature. It was found that single layer of TiO2 showed anatase polycrystalline structure. It also exhibited high visible transmittance of above 80% and higher refractive index of 2.31 at a wavelength of 550 nm. The indirect optical band gap of the TiO2 films was estimated as 3.39 eV. The Ag single layer films were found to be crystalline with a very high reflectance for IR (Infra-red) light. Finally, the multi-layers have been deposited and characterized by X-ray diffraction, UV-visible-NIR spectro-photometry, scanning electron microscopy and Auger electron spectroscopy.

M. M. Hasan; A. B. M. Malek; A. S. M. A. Haseeb; H. H. Masjuki

2010-01-01

343

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

UK PubMed Central (United Kingdom)

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.

Ge L; Liu N; Yang P; Cheng X

2013-04-01

344

Photocatalytic activity and reusability study of nanocrystalline TiO2 films prepared by sputtering technique  

Science.gov (United States)

The photocatalytic activity of nanocrystalline titanium dioxide (TiO2) films deposited on unheated glass substrates by DC reactive magnetron sputtering at different oxygen partial pressures was tested on the decolorization of Rhodamine 6G (Rh6G) aqueous solutions. The dye photodecolorization process was studied considering the influence of the crystallinity and preferred orientation of growth of the prepared films. It was found that the higher photocatalytic activity was achieved by the film with preferred orientation of growth along the (1 0 1) crystal direction and showing a vestigial rutile phase in a mainly anatase phase. The recycling catalytic ability of the TiO2 films was also evaluated and a promising photocatalytic performance has been revealed with a very low variation of the decay rate after five consecutive usages. Structural and morphological characterization revealed high photochemical stability of the films after successive photodegradations assays.

Barrocas, B.; Monteiro, O. C.; Jorge, M. E. Melo; Sério, S.

2013-01-01

345

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

346

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 r = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.

Šícha J; He?man D; Musil J; Strýhal Z; Pavlík J

2007-01-01

347

Nanometer-thin TiO2 enhances skeletal muscle cell phenotype and behavior  

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Full Text Available Ken Ishizaki*, Yoshihiko Sugita*, Fuminori Iwasa, Hajime Minamikawa, Takeshi Ueno, Masahiro Yamada, Takeo Suzuki, Takahiro OgawaLaboratory for Bone and Implant Sciences, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA*Authors contributed equally to this workBackground: The independent role of the surface chemistry of titanium in determining its biological properties is yet to be determined. Although titanium implants are often in contact with muscle tissue, the interaction of muscle cells with titanium is largely unknown. This study tested the hypotheses that the surface chemistry of clinically established microroughened titanium surfaces could be controllably varied by coating with a minimally thin layer of TiO2 (ideally pico-to-nanometer in thickness) without altering the existing topographical and roughness features, and that the change in superficial chemistry of titanium is effective in improving the biological properties of titanium.Methods and results: Acid-etched microroughened titanium surfaces were coated with TiO2 using slow-rate sputter deposition of molten TiO2 nanoparticles. A TiO2 coating of 300 pm to 6.3 nm increased the surface oxygen on the titanium substrates in a controllable manner, but did not alter the existing microscale architecture and roughness of the substrates. Cells derived from rat skeletal muscles showed increased attachment, spread, adhesion strength, proliferation, gene expression, and collagen production at the initial and early stage of culture on 6.3 nm thick TiO2-coated microroughened titanium surfaces compared with uncoated titanium surfaces.Conclusion: Using an exemplary slow-rate sputter deposition technique of molten TiO2 nanoparticles, this study demonstrated that titanium substrates, even with microscale roughness, can be sufficiently chemically modified to enhance their biological properties without altering the existing microscale morphology. The controllable and exclusive chemical modification technique presented in this study may open a new avenue for surface modifications of titanium-based biomaterials for better cell and tissue affinity and reaction.Keywords: nanotechnology, orthopedic implants, molten TiO2 nanoparticles, surface chemistry

Ishizaki K; Sugita Y; Iwasa F; Minamikawa H; Ueno T; Yamada M; Suzuki T; Ogawa T

2011-01-01

348

Thirdª²order Nonlinear Optical Properties of TiO2 Films  

Directory of Open Access Journals (Sweden)

Full Text Available Anatase TiO2 films were fabricated on fused quartz by pulsed laser deposition £¨PLD£© technique and the single-phase anatase films were obtained under the optimal conditions. The X-ray diffraction and atomic force microscope were used to investigate the structure and surface characters of the film. The third-order optical nonlinearities of the films were measured by Z-scan technique using a femtosecond laser (50fs) of 800nm. From the transmission spectra, the optical bandª²gap and linear refractive index of the TiO2 film are determined to be 3.18eV and 2.1, respectively. The nonlinear absorption coefficient and nonlinear refractive index are determined to be -6.2¡?0-11m/W and -6.32¡?0-17m2/W, respectively.The real and imaginary parts of third-order nonlinear susceptibility ¦?3) are determined to be -7.1¡?0-11esu and -4.42¡?0-12esu, respectively. And the following figure of merit T=¦¦?n2 is calculated to be 0.8 for the film, indicating that the anatase TiO2 films have great potential applications to nonlinear optical devices.

LONG Hua,CHEN Ai-Ping,YANG Guang,LI Yu-Hua,LU Pei-Xiang

2009-01-01

349

Photocatalysts of Cr Doped TiO2 Film Prepared by Micro Arc Oxidation  

Science.gov (United States)

A series of Cr doped TiO2 films were prepared by micro arc oxidation (MAO) using an electrolyte of Na3PO4+K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3+/Cr4+ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band (CB) and valence band (VB) of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.

Wan, Li; Li, Jian-feng; Feng, Jia-you; Sun, Wei; Mao, Zong-qiang

2008-10-01

350

Optical, dielectric and morphological studies of sol-gel derived nanocrystalline TiO2 films.  

Science.gov (United States)

Nanocrystalline TiO(2) films have been synthesized on glass and silicon substrates by sol-gel technique. The films have been characterized with optical reflectance/transmittance in the wavelength range 300-1000 nm and the optical constants (n, k) were estimated by using envelope technique as well as spectroscopic ellipsometry. Morphological studies have been carried out using atomic force microscope (AFM). Metal-Oxide-Silicon (MOS) capacitor was fabricated using conducting coating on TiO(2) film deposited on silicon. The C-V measurements show that the film annealed at 300 degrees C has a dielectric constant of 19.80. The high percentage of transmittance, low surface roughness and high dielectric constant suggests that it can be used as an efficient anti-reflection coating on silicon and other optical coating applications and also as a MOS capacitor. PMID:19717333

Vishwas, M; Sharma, Sudhir Kumar; Narasimha Rao, K; Mohan, S; Gowda, K V Arjuna; Chakradhar, R P S

2009-08-05

351

Optical, dielectric and morphological studies of sol-gel derived nanocrystalline TiO2 films.  

UK PubMed Central (United Kingdom)

Nanocrystalline TiO(2) films have been synthesized on glass and silicon substrates by sol-gel technique. The films have been characterized with optical reflectance/transmittance in the wavelength range 300-1000 nm and the optical constants (n, k) were estimated by using envelope technique as well as spectroscopic ellipsometry. Morphological studies have been carried out using atomic force microscope (AFM). Metal-Oxide-Silicon (MOS) capacitor was fabricated using conducting coating on TiO(2) film deposited on silicon. The C-V measurements show that the film annealed at 300 degrees C has a dielectric constant of 19.80. The high percentage of transmittance, low surface roughness and high dielectric constant suggests that it can be used as an efficient anti-reflection coating on silicon and other optical coating applications and also as a MOS capacitor.

Vishwas M; Sharma SK; Narasimha Rao K; Mohan S; Gowda KV; Chakradhar RP

2009-10-01

352

Deposition of TiO2 films by reactive sputtering in magnetic field  

International Nuclear Information System (INIS)

When TiO2 films are deposited on a Si substrate, the magnetic screening of the substrate is proposed to reduce the deep-level trap by Ti atom bombardment. The substrate is placed in the field of a permanent magnet. It is found that the films deposited with the magnet do not form any deep level in the substrate, and exhibit better optical property and crystalline structure than those deposited without the magnet. (author).

1991-01-01

353

Multistep electron transfer processes on dye co-sensitized nanocrystalline TiO2 films.  

UK PubMed Central (United Kingdom)

We report a method for achieving multilayer co-sensitization of nanocrystalline TiO2 films. The method is based upon an aluminum isopropoxide treatment of the monosensitized film prior to deposition of a second sensitizer. Appropriate selection of sensitizer dyes allows vectorial, multistep, electron transfer processes, resulting in a suppression of interfacial charge recombination and a significantly improved photovoltaic device performance relative to single-layer co-sensitization devices.

Clifford JN; Palomares E; Nazeeruddin MK; Thampi R; Grätzel M; Durrant JR

2004-05-01

354

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

355

Electrophoretic deposition of TiO2 film on titanium foil for a flexible dye-sensitized solar cell  

International Nuclear Information System (INIS)

[en] Electrophoretic deposition (EPD) method is employed to obtain mesoporous TiO2 film on a titanium (Ti) foil; the film is then mechanically compressed and sintered at 350 deg. C before being subjected to dyeing. A comprehensive study was made on the mechanistic aspects of the EPD process. The dye-sensitized solar cell (DSSC) using the thus formed TiO2 film rendered a power conversion efficiency (Eff.) of 6.5%. Effects of various compression pressures on the photovoltaic parameters and on other characteristic parameters of the pertinent DSSCs are studied. Electrochemical impedance spectroscopy (EIS) is applied for the first time, using a novel equivalent model, to study the impedance behavior of the DSSC with this type of TiO2 film. We also obtain characteristic parameters of the TiO2 photoanode by using EIS. The coordination number of the TiO2 film, and the ratio of charge transfer resistances of electron recombination and electron transport are also obtained and analyzed. Moreover, we employ a multilayer approach and increase the film thickness to prepare TiO2 films with the same coordination number and porosity; DSSCs using such TiO2 films obtained from P90 and P25 rendered efficiencies of 6.5% and 5.24%, respectively. Scanning electron microscopy (SEM) micrographs are obtained to characterize the TiO2 films formed by the EPD technique and laser-induced transient technique is used to estimate the electron lifetime in the TiO2 films.

2011-09-30

356

Preparation of cerium-doped TiO2 film on 304 stainless steel and its bactericidal effect in the presence of sulfate-reducing bacteria (SRB)  

International Nuclear Information System (INIS)

Cerium-doped TiO2 film with bactericidal activity was prepared on 304 stainless steel by a sol-gel process. The doped cerium ions were identified to have retarding effect on the phase transition from amorphous TiO2 to anatase TiO2. This effect was interpreted as the distortion of crystal lattice, due to the introduction of cerium ions into the crystal structure of TiO2. The absorption band edge of cerium-doped TiO2 film has a red shift compared with that of pure TiO2 film in UV-vis spectra. The films covered with sulfate-reducing bacteria (SRB) medium were exposed to sunlight for 6 h and the bactericidal efficiency was evaluated with most probable number technique. It was found that the bactericidal efficiency of cerium-doped TiO2 film and pure TiO2 film were 95% and 85%, respectively.

2010-11-01

357

State selective electron injection in non-aggregated titanium phthalocyanine sensitised nanocrystalline TiO2 films.  

UK PubMed Central (United Kingdom)

We describe a novel titanium phthalocyanine that shows no aggregation when anchored to nanocrystalline TiO2 films through its axial carboxylated ligand without the use of co-adsorbents; state selective electron injection into the TiO2 is demonstrated, resulting in efficient photocurrent generation in dye sensitised photoelectrochemical solar cells.

Palomares E; Martinez-Diaz MV; Haque SA; Torres T; Durrant JR

2004-09-01

358

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 %.

2008-01-01

359

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

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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 hydro...

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

360

Hydrophilicity, photocatalytic activity and stability of tetraethyl orthosilicate modified TiO2 film on glazed ceramic surface  

Science.gov (United States)

A new, simple, and low-cost method has been developed to enhance the surface properties of TiO2 film. Degussa P25-TiO2 nanoparticles were modified by tetraethyl orthosilicate (TEOS) on glazed ceramic tiles. Effects of tetraethyl orthosilicate modification on microstructure, crystal structure, hydrophilicity, photocatalytic activity and stability of the film were investigated. The obtained results showed that P25-TiO2/TEOS particles exhibited better dispersion, higher surface area, bigger surface roughness and smaller particle size comparing to pure P25-TiO2 particles, which resulted in better hydrophilicity after 10 days in a dark place and higher photocatalytic activity under visible light irradiation. 68% of Rhodamine B was degraded by P25-TiO2/TEOS film in 25 h with the light intensity of 5000 ± 500 lx, and degradation rate reached to 82% with the light intensity of 10,000 ± 1000 lx. Furthermore, two fundamentally different systems, in which the films recycle for repetitive degradation after soaked in dye solution and for discoloration after depositing dye on the surfaces, respectively, were measured to confirm that P25-TiO2/TEOS film showed excellently stable performances. Therefore the P25-TiO2/TEOS film we obtained has good washing resistance and would be a promising candidate for practical applications.

Zhang, Peng; Tian, Jie; Xu, Ruifen; Ma, Guojun

2013-02-01

 
 
 
 
361

Effect of oxygen partial pressure on the ferromagnetism of Cr-doped TiO2 films  

International Nuclear Information System (INIS)

Polycrystalline Cr-doped TiO2 films were fabricated by co-sputtering Cr and TiO2 targets in a pure Ar and O2 mixture with various oxygen partial pressures. Ferromagnetism is observed in all samples and the Curie temperatures are well above 390 K. The saturation magnetization of films shows strong dependence on the oxygen growth pressure while keeping a constant Cr concentration. The ferromagnetism is enhanced in the films deposited at lower oxygen pressures which are thus oxygen deficient, indicating an important role of oxygen vacancies in the ferromagnetic origin of Cr-doped TiO2.

2008-01-07

362

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

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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.

Marye Anne Fox; James K. Whitesell; Douglas Magde; Lin-Yong Zhu

2009-01-01

363

W-doped anatase TiO2 transparent conductive oxide films: Theory and experiment  

International Nuclear Information System (INIS)

W-doped anatase TiO2 films were deposited on glass substrate by magnetron cosputtering. The minimum resistivity, 1.5x10-2 ? cm, for Ti1-xWxO2 film (x=0.063) was obtained. X-ray photoelectron spectroscopy analysis shows W incorporated in the Ti lattice position is mostly in the W6+ state. Theoretical calculations based upon the density-functional theory were applied to analyze the electronic structure and conducting mechanism. The strong hybridization of Ti 3d states with W 5d states is the dominate factor to cause the shifting in Fermi level into conduction band. Our results suggest that tungsten is a favorable dopant to form TiO2-based transparent conducting oxide materials.

2010-03-15

364

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

365

Phase evolution of sol-gel prepared Pb(Zr0.3Ti0.7)O3 thin films deposited on IrO2/TiO2/SiO2/Si electrodes  

International Nuclear Information System (INIS)

We report on the microstructural analyses, by means of X-ray diffraction (XRD), scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDX) and cross-section transmission electron microscopy (X-TEM), of chemically prepared Pb(Zr0.3Ti0.7)O3 thin films deposited on IrO2 substrates. The purpose of this study is to detail temperature and time dependence of the lead zirconate titanate (PZT) film microstructure on this type of conductive oxide substrate, partly through a comparison with identically processed PZT films deposited on Pt substrates. It was observed that PZT 30/70 films on IrO2 bottom electrodes, fired at temperatures up to 620 deg. C, are not single phase, due to extensive lead losses during the processing. The IrO2 substrate was found to be indirectly responsible for these losses. Nevertheless, good ferroelectric properties were measured (Pr was 50 ?C/cm2 for the 620 deg. C film). Based on the observed morphology and texture with increasing annealing time, a mechanism for phase evolution in sol-gel-derived PZT 30/70 films on IrO2 substrates is proposed

2004-11-22

366

Electronic and transport properties of reduced and oxidized nanocrystalline TiO2 films  

International Nuclear Information System (INIS)

Electronic properties of reduced (vacuum-annealed) and oxidized (air-annealed) TiO2 films were investigated by in situ conductivity and current-voltage measurements as a function of the ambient oxygen pressure and temperature, and by ex situ surface photovoltage spectroscopy. The films were quite conductive in the reduced state but their resistance drastically increased upon exposure to air at 350 deg. C. In addition, the surface potential barrier was found to be much larger for the oxidized versus the reduced films. This behavior may be attributed to the formation of surface and grain boundary barriers due to electron trapping at interface states associated with chemisorbed oxygen species

2003-01-27

367

Influence of crystallinity on CO gas sensing for TiO2 films  

International Nuclear Information System (INIS)

[en] In the present research, carbon monoxide (CO) gas sensing response was studied for TiO2 thick films calcined and sintered between 700 and 900 deg. C. Crystalline phase, crystallite size, surface area, particle size, and amorphous content were measured for the calcined powder. Crystallinity of the powder was found to affect sensing response significantly towards CO. Anatase phase of TiO2 thick film was stable up to 900 deg. C however, as calcination temperature increased from 700 to 900 deg. C, surface area and amorphous phase content decreased. Films calcined and sintered at 700 deg. C showed a lower response towards CO than those calcined at 800 deg. C. Upon increasing the calcination temperature further, particle growth and reduced surface area hindered the sensing response. A calcination temperature of 800 deg. C was necessary to achieve sufficient order in the crystal structure leading to more efficient adsorption and desorption of oxygen ions on the surface of TiO2.

2009-08-15

368

Low-temperature liquid phase deposited TiO2 films on stainless steel for photogenerated cathodic protection applications  

International Nuclear Information System (INIS)

[en] The low-temperature synthesis of anatase TiO2 films was an imperative requirement for their application to corrosion prevention of metals. In this paper, a liquid phase deposition (LPD) technique was developed to prepare TiO2 films on SUS304 stainless steel (304SS) at a relatively low temperature (80 deg. C). The as-prepared films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photon spectroscopy (XPS). It was observed that a dense and crack-free anatase TiO2 film with a thickness about 300 nm was obtained. The film contained some fluorine and nitrogen elements, and the amounts of these impurities were greatly decreased upon calcination. Under the white light illumination, the electrode potential of TiO2 coated 304SS rapidly shifted to a more negative direction. Moreover, the photopotential of TiO2/304SS electrode showed more negative values with increased film thickness. In conclusion, the photogenerated cathodic protection of 304SS was achieved by the low-temperature LPD-derived TiO2 film.

2011-06-01

369

Understanding bactericidal performance on ambient light activated TiO2-InVO4 nanostructured films  

Science.gov (United States)

TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film.TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film. Electronic supplementary information (ESI) available: Photocatalytic activity test procedure and results, AFM images, EDX results, LSCM images, and wettability results. See DOI: 10.1039/c1nr11126d

He, Ziming; Xu, Qingchi; Yang Tan, Timothy Thatt

2011-12-01

370

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.

2012-01-01

371

Photocatalytic behaviour of metal-loaded TiO2 aqueous dispersions and films  

International Nuclear Information System (INIS)

Titanium dioxide nanoparticles loaded with Ce, Co, Eu, Sm, W and Yb species were prepared by coprecipitation in mild conditions using TiCl4 as precursor with the aim to enhance the photocatalytic activity, especially under visible light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the powders of pure and loaded TiO2 was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with suitable amounts of W, Co and Sm resulted in a significant improvement of the photoreactivity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole pairs. Some samples were more photoactive than commercial powders employed in the same experimental conditions. Films of TiO2 loaded with the metals that yielded the best photocatalytic responses were prepared by the dip-coating technique. The photoactivity of the films was tested by evaluating the rate of degradation of 2-propanol in a gas-solid system. An enhancement of the photocatalytic efficiency was obtained in the presence of W and Sm.

2007-10-15

372

Formation of nano-phase hydroxyapatite film on TiO2 nano-network.  

UK PubMed Central (United Kingdom)

Nano- and micro-phase HA film formed on TiO2 nano-network surface by simple electrochemical treatment. The range of lateral pore size of the network specimen was about 10-120 nm on Ti surface by anodized in 5 M NaOH solution at 0.3 A for 10 min. Nano-network TiO2 surface were formed by this anodization step which acted as templates and anchorage for growth of the HA during subsequent pulsed electrochemical deposition process at 85 degrees C. The phase and morphologies of deposits HA were influenced by the electrolyte concentration. The nano needle-like precipitates formed under low SBF concentration were identified to be HA crystals orientated parallel to the c-axis direction. Increasing electrolyte concentration, needle-like deposits transferred to the plate-like and micro plate like precipitates in the case of high SBF concentration.

Lee K; Ko YM; Choe HC; Kim BH

2012-01-01

373

Determantion of thresold random gain medium in dye: Polymer films contunining TiO2 nanoparticles  

Directory of Open Access Journals (Sweden)

Full Text Available Random gain medium based on organic Rhodamine 590 (R590) laser-dye and Titanium dioxide (TiO2) suspended nanoparticles have been prepared with polymethylmethacrylate (PMMA) as a host. Spray-coated homogeneous film samples of 22.4 µm thickness. Optimum concentrations have been determined depending on the normal fluorescence spectra which give evidence that the laser dye provides amplification and TiO2 nanoparticles act as scatter center. At the optimum concentrations, results of the random gain medium under second harmonic Nd: YAG laser excitation shows that the values of bandwidth at full width half-maximum (FWHM) and the threshold energy are about 11 nm and 10 mJ respectively.

Baha T. Chiad; Mohammed A. Hameed; Firas J. Kadhim; Kamil H. Latif

2012-01-01

374

Effect of substrate on surface morphology and photocatalysis of large-scale TiO2 films  

Science.gov (United States)

Nanostructured TiO2 films were prepared on a variety of substrates, including acid frosted soda-lime glass, acid frosted soda-lime glass pre-coated with a SiO2 barrier layer, commercial glazed ceramic tile and 6061 aluminum alloy. For each substrate, the phase and microstructure of the films were determined to be exclusively anatase. However, the growth of the TiO2 crystallites, the film morphology and thickness varied substantially with substrate. Thermal stress, resulting from the difference in the coefficient of thermal expansion between the substrates and the films, contributed to the formation and propagation of cracks. This was most clearly observed on the films deposited on SiO2 barrier layer and aluminum. The photocatalytic activity of the TiO2 films deposited on glass with and without SiO2 barrier layer, ceramic, and aluminum was studied via UV decolorization of methyl orange in aqueous solution. Complete degradation rapidly occurred on the TiO2/glass and TiO2/SiO2 barrier layer films, but not with the ceramic or metal substrates. It appears that the photocatalytic activity of the films deposited on aluminum and ceramic substrates was affected by the quantity and the size of the anatase crystallites. The aluminum substrate promoted the formation of TiO2 films with the largest anatase crystallite size, exhibiting a cracked morphology, where as the ceramic substrate resulted in the formation of TiO2 films with large crystallite size in an island morphology.

Lopez, Lorena; Daoud, Walid A.; Dutta, Dushmanta; Panther, Barbara C.; Turney, Terence W.

2013-01-01

375

Effect of dye concentration on electron injection efficiency in nanocrystalline TiO2 films sensitized with N719 dye  

Science.gov (United States)

The efficiency of electron injection from excited N719 dye to nanocrystalline TiO2 films was studied in films with several different dye loads by means of time-resolved microwave conductivity measurements. High-efficiency electron injection was observed in all films. The adsorption data could be fitted to the Langmuir-type isotherm, and the absorption spectra of N719 adsorbed on the TiO2 films did not vary with dye loading. These findings suggest that no dye aggregation occurred on the films even at full coverage condition.

Katoh, Ryuzi; Yaguchi, Kaori; Furube, Akihiro

2011-08-01

376

Acid versus base peptization of masoporous nanocrystalline TiO2 films. Functional studies in dye sensitized solar cells  

Energy Technology Data Exchange (ETDEWEB)

We report an analysis of the influence of acid/base conditions employed in the synthesis of TiO2 nanoparticles upon the performance of dye sensitised photoelectrochemical solar cells fabricated from these particles. The functional properties of the TiO2 nanoparticles in these devices are investigated by potential step chronoperometry, transient laser spectroscopy, and photovoltaic device characterisation. We find that base peptization conditions employed in the sol-gel fabrication of the TiO2 nanoparticles result in a reduction in film electron density under negative applied bias, correlated with slower interfacial recombination losses and a higher device open circuit voltage.

Hore, S.; Hinsch, A. [Freiburg Materials Research Center, Freiburg (Germany); Polamares, E.; Durrant, J.R. [Centre for Electronic Materials and Devices, The Blackett Laboratory Imperial College of Science, Technology and Medicine, London (United Kingdom); Smit, H.J.P.; Bakker, N.J.; Kroon, J.M. [ECN Solar Energy, Petten (Netherlands); Comte, P.; Liska, P.; Thampi, K.R. [Ecole polytechnique federale de Lausanne, Institut des sciences et ingenierie chimiques EPFL, Lausanne (Switzerland)

2005-01-01

377

Co3O4/TiO2 films obtained by laser ablation and sol-gel for the reaction of oxygen liberation in alkaline medium  

International Nuclear Information System (INIS)

The laser ablation technique known as Pulsed Laser Deposition (PLD) is used for obtaining thin films of TiO2/SnO2, which was later modified with Co3O4 by PLD or by sol-gel technique. The films were characterized by X-ray diffraction, ultraviolet Vis and Raman spectroscopies, scanning electron microscopy and energy analysis of the dispersed X-rays produced by Auger decay. The anatase phase with particles of nano metric size was obtained by depositing the titanium dioxide in argon atmosphere. The Co3O4 films obtained by PLD on the TiO2 showed the same morphology. The electrocatalytic activity of the films that were used as photo anodes for the reaction of oxygen liberation was carried out in the darkness, with environment light and the light emitted by a xenon lamp. The current density was higher for films of Co3O4/TiO2/SnO2 obtained by PLD that for cobalt dioxide of mixed valence obtained by sol-gel. (Author)

2008-01-01

378

Morphologically-tunable TiO2 nanorod film with high energy facets: green synthesis, growth mechanism and photocatalytic activity.  

UK PubMed Central (United Kingdom)

A novel green synthesis strategy was developed to synthesize a film photocatalyst containing anatase TiO(2) nanorods wholly dominated with {100} and {101} facets by employing a simple hydrothermal reaction in the presence of NaCl solution and hydrogen titanate nanosheet array film. The formation mechanism of the anatase TiO(2) nanorods was deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations, which revealed that the highly reactive {100} facets were derived from the enhanced structural stability of hydrogen titanate induced by Na(+) and selective adsorption of Cl(-) on the {100} facets of anatase TiO(2) crystals. Photocatalytic performance has indicated that the TiO(2) nanorods with {100} facet exposure exhibit much higher activities than that of rhombic nanoparticles with {101} facet exposure for the degradation of organic contaminants, which may be primarily ascribed to the high surface energy of {100} facets.

Wang C; Zhang X; Zhang Y; Jia Y; Yuan B; Yang J; Sun P; Liu Y

2012-08-01

379

Simultaneous Bulk and Surface Plasmon Resonance and Radiative Polaritons excited in RuO2 films grown on glass and on TiO2 (001)  

Science.gov (United States)

Conducting oxides, such as RuO2, have a much lower carrier concentration as compared to metals, leading to a lower plasma frequency of 3.3eV which lies in the infrared (IR) region. This unique feature of conducting oxides allows for simultaneous observation of surface and bulk polariton modes in the IR range. Here we have investigated bulk and surface plasmons as well as radiative polaritons in RuO2 thin films. The RuO2 thin films investigated were grown using DC magnetron sputtering on glass and on TiO2 (001). We have used X-ray Diffraction and Reflection High-Energy Electron Diffraction to characterize the microstructure of these samples. Four-point probe and ellipsometry were used to investigate the electrical conductivity and the optical properties. The optical measurements were carried out using HeNe red laser (632nm) and IR laser (1520nm) radiations to illuminate RuO2 thin films. We will show that bulk plasmons can be excited in RuO2 thin films in the visible red region, while simultaneous bulk plasmons as well as surface plasmons excitation are observed in the IR region. We also studied the substrate influence on the radiative polaritons in the middle IR region (20-2.2um) by measuring films grown on glass and on TiO2 (001).

Wang, L.; Clavero, C.; Yang, K.; Radue, E.; Scarel, G.; Novikova, I.; Lukaszew, R.

2012-02-01

380

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

 
 
 
 
381

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

382

Synthesis and Characterization of Filtered-cathodic-vacuum-arc-deposited TiO2 Films for Photovoltaic Applications  

Science.gov (United States)

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.

Aramwit, C.; Intarasiri, S.; Bootkul, D.; Tippawan, U.; Supsermpol, B.; Seanphinit, N.; Ruangkul, W.; Yu, L. D.

2013-04-01

383

Synthesis and photocatalytic properties of porous TiO2 films prepared by ODA/sol-gel method  

International Nuclear Information System (INIS)

Porous TiO2 films were deposited on SiO2 pre-coated glass-slides by sol-gel method using octadecylamine (ODA) as template. The amount of ODA in the sol played an important role on the physicochemical properties and photocatalytic performance of the TiO2 films. The films prepared at different conditions were all composed of anatase titanium dioxide crystals, and TiO2 crystalline size got larger with increasing ODA amount. The maximum specific surface area of 41.5 m2/g was obtained for TiO2 powders prepared from titanium sol containing 2.0 g ODA. Methyl orange degradation rate was enhanced along with increasing ODA amount and reached the maximal value at 2.0 g addition of ODA. After 40 min of UV-light irradiation, methyl orange degradation rate reached 30.5% on the porous film, which was about 10% higher than that on the smooth film. Porous TiO2 film showed almost constant activity with slight decrease from 30.5% to 28.5% after 4 times of recycles.

1101-01-00

384

Photocatalytic reactor using titanium dioxide thin film on quartz tubes  

Science.gov (United States)

Photocatalysis process, as an environmental application is an advanced oxidation process with tremendous potential in the near future. Previously many researchers, have conducted photocatalysis in different reactor configuration using TiO2 slurry and thin film, using a UV light source, the constraints for these reactors are the need for the removal of TiO2 particles at the outlet stream in a slurry reactor and poor environment for the efficient use of TiO2 film using UV light, as the UV light penetration depth in water is about an inch. Taking all this into consideration, we propose a design for reactor with efficient contact of the aqueous phase to the TiO2 film so that UV light doesn't need to penetrate through water, the TiO2 particles need not be removed from the outlet stream of water. The wok involves the deposition of TiO2 on quartz tubes with TiO2 and TiO2-Fe doped film by sol-gel and ESA (electrostatic self assembly) method and testing the performance of the coated film in proposed photocatalytic reactor in degradation of congo red, KI and Nitro phenol.

Kouda, Ram Mahipal

385

Mesoporous inverse opal TiO2 film as light scattering layer for dye-sensitized solar cell.  

Science.gov (United States)

The light harvesting efficiency of dye-sensitized solar cells was enhanced by using a scattering layer. Such as sphere type TiO2, inverse photonic crystal TiO2, hollow spherical TiO2. Among these materials, the TiO2 with inverse photonic crystal (IPC) structure, synthesized by self-assembly using spherical templates, has attracted much attention due to their photonic crystal characteristics and light scattering effects. However, when applied in the DSSCs, the surface area of IPC is very low that caused insufficient adsorption amount of dye molecules. In the present work, a scattering layer with mesoporous inverse photonic crystal (MIPC) TiO2 film was fabricated by the sol-gel reactions with surfactant-assisted sol-gel method using poly(methyl methacrylate) as the template and titanium (IV) isopropoxide as the TiO2 precursor. After removing the PMMA and surfactant, a highly ordered macroporous structure with mesopores were successfully obtained. The surface area and total pore volume of the MIPC were 82 m2/g and 0.31 cm3/g, respectively, which is much larger than those of the IPC. The DSSCs with the scattering layer of MIPC film exhibited 18 and 10% higher photo-conversion efficiency than those of cells only with a nano-crystalline TiO2 film and with scattering layer of IPC film. From UV-visible spectra of dye solutions, the MIPC film showed a higher amount of absorbed dye molecules than those of the reference and IPC films. Accordingly, an increase in the photo-current density through abundant adsorption of the dye, coupled with inherent light scattering ability can improve overall photo-conversion efficiency. PMID:22524063

Jin, Mingshi; Kim, Sung Soo; Yoon, Minyoung; Li, Zhenghua; Lee, Yoon Yun; Kim, Ji Man

2012-01-01

386

Mesoporous inverse opal TiO2 film as light scattering layer for dye-sensitized solar cell.  

UK PubMed Central (United Kingdom)

The light harvesting efficiency of dye-sensitized solar cells was enhanced by using a scattering layer. Such as sphere type TiO2, inverse photonic crystal TiO2, hollow spherical TiO2. Among these materials, the TiO2 with inverse photonic crystal (IPC) structure, synthesized by self-assembly using spherical templates, has attracted much attention due to their photonic crystal characteristics and light scattering effects. However, when applied in the DSSCs, the surface area of IPC is very low that caused insufficient adsorption amount of dye molecules. In the present work, a scattering layer with mesoporous inverse photonic crystal (MIPC) TiO2 film was fabricated by the sol-gel reactions with surfactant-assisted sol-gel method using poly(methyl methacrylate) as the template and titanium (IV) isopropoxide as the TiO2 precursor. After removing the PMMA and surfactant, a highly ordered macroporous structure with mesopores were successfully obtained. The surface area and total pore volume of the MIPC were 82 m2/g and 0.31 cm3/g, respectively, which is much larger than those of the IPC. The DSSCs with the scattering layer of MIPC film exhibited 18 and 10% higher photo-conversion efficiency than those of cells only with a nano-crystalline TiO2 film and with scattering layer of IPC film. From UV-visible spectra of dye solutions, the MIPC film showed a higher amount of absorbed dye molecules than those of the reference and IPC films. Accordingly, an increase in the photo-current density through abundant adsorption of the dye, coupled with inherent light scattering ability can improve overall photo-conversion efficiency.

Jin M; Kim SS; Yoon M; Li Z; Lee YY; Kim JM

2012-01-01

387

(I2)n-encapsulated and C-encapsulated TiO2 films: Enhanced photoelectrochemical and visible-light photoelectrocatalytic properties  

International Nuclear Information System (INIS)

[en] Highlights: ? (I2)n-encapsulated TiO2 (I2-TiO2) and C-encapsulated TiO2 (C-TiO2) film electrodes were prepared. ? I2-TiO2 and C-TiO2 films show improved light absorbance in 400–550 nm. ? Lower electron transfer resistance and more negative flat band potentials were obtained from them. ? The photoelectrocatalytic activities of I2-TiO2 and C-TiO2 films were much higher than TiO2 film. - Abstract: Visible-light absorbing (I2)n-encapsulated TiO2 film (I2-TiO2 film) and C-encapsulated TiO2 film (C-TiO2 film) were fabricated and studied as film electrodes for their photoelectrochemical and photoelectrocatalytic (PEC) properties. The as-prepared film electrodes were characterized by scanning electronic microscopy, energy-dispersive X-ray spectroscopy and UV–visible diffuse reflectance spectroscopy. The photoelectrochemical properties were evaluated by the incident photo-to-current conversion efficiency, electrochemical impedance spectroscopy and Mott–Schottky analysis data. The results showed that I2-TiO2 and C-TiO2 films exhibited stronger absorption in the 400–550 nm range, lower electron transfer resistance and more negative flat band potentials comparing with pure TiO2 film. Moreover, the photoelectrochemical ability of I2-TiO2 film is superior to that of C-TiO2 film. At a bias potential of 0.5 vs (Ag/AgCl)/V, the visible-light-induced PEC degradation ratios of rhodamine B and tetracycline on I2-TiO2 film or C-TiO2 film electrodes exceeded that on pure TiO2 electrode, with the improvement by a factor of about 5 or 3. The higher PEC activity of I2-TiO2 film and C-TiO2 film could be attributed to the enhancement of separation of electron-hole pair at the external electric field and the extension of the light response range of TiO2 to the visible light with a red shift in the band gap transition.

1000-01-00

388

Site-dependent electron-stimulated reactions in water films on TiO2(110).  

Science.gov (United States)

Electron-stimulated reactions in thin [1 ML, the water ESD yield per additional water molecule adsorbed (i.e., the slope of the ESD yield versus coverage) is 3.5 times larger than for theta1 ML due to the increased water ESD for those coverages. The water ESD yields versus electron energy (for 5-50 eV) are qualitatively similar for 1, 2, and 40 ML water films. In each case, the observed ESD threshold is at approximately 10 eV and the yield increases monotonically with increasing electron energy. The results indicate that excitations in the adsorbed water layer are primarily responsible for the ESD in thin water films on TiO(2)(110). Experiments on "isotopically layered" films with D(2)O adsorbed on the Ti(4+) sites (D(2)O(Ti)) and H(2)O adsorbed on the bridging oxygen atoms (H(2)O(BBO)) demonstrate that increasing the water coverage above 1 ML rapidly suppresses the electron-stimulated desorption of D(2)O(Ti) and D atoms, despite the fact that the total water ESD and atomic hydrogen ESD yields increase with increasing coverage. The coverage dependence of the electron-stimulated reactions is probably related to the different bonding geometries for H(2)O(Ti) and H(2)O(BBO) and its influence on the desorption probability of the reaction products. PMID:18081413

Lane, Christopher D; Petrik, Nikolay G; Orlando, Thomas M; Kimmel, Greg A

2007-12-14

389

Zn-doped nanocrystalline TiO2 films for CdS quantum dot sensitized solar cells.  

UK PubMed Central (United Kingdom)

Quantum dot-sensitized solar cells based on Zn-doped TiO(2) (Zn-TiO(2)) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO(2) nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO(2)/CdS film and the photovoltaic performance of the Zn-TiO(2)/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO(2) film was adopted as the photoanode of CdS QDSSCs instead of only the TiO(2) layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO(2) film by Zn doping.

Zhu G; Cheng Z; Lv T; Pan L; Zhao Q; Sun Z

2010-07-01

390

Zn-doped nanocrystalline TiO2 films for CdS quantum dot sensitized solar cells  

Science.gov (United States)

Quantum dot-sensitized solar cells based on Zn-doped TiO2 (Zn-TiO2) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO2 nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO2/CdS film and the photovoltaic performance of the Zn-TiO2/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO2 film was adopted as the photoanode of CdS QDSSCs instead of only the TiO2 layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO2 film by Zn doping.

Zhu, Guang; Cheng, Zujun; Lv, Tian; Pan, Likun; Zhao, Qingfei; Sun, Zhuo

2010-07-01

391

High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance  

DEFF Research Database (Denmark)

We report on high-quality polycrystalline Fe-doped TiO2 (Fe–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 Fe–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

392

Visible-light-driven photogenerated cathodic protection of stainless steel by liquid-phase-deposited TiO2 films  

International Nuclear Information System (INIS)

[en] Highlights: ? The N–F-codoped TiO2 films were prepared on FTO substrate by liquid-phase-deposition. ? The TiO2 films showed a visible-light response in the wavelength of 600–750 nm. ? The TiO2 film exhibited an effective photogenerated cathodic protection for 304SS. - Abstract: The liquid-phase-deposition (LPD) method was developed to prepare N–F-codoped TiO2 films that served as photoanodes for the cathodic protection of SUS304 stainless steel (304SS). The as-prepared LPD-TiO2 films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Photoelectrochemical properties, such as open-circuit potential (OCP), photocurrent spectra, Tafel polarization curves and electrochemical impedance spectroscopy (EIS) of the LPD-TiO2 films, were also measured. The results indicate that the LPD-TiO2 films showed a visible-light response in the wavelength range of 600–750 nm. The photocurrent intensities in both the ultraviolet (UV)-light and visible-light regions were enhanced as the heat treatment (HT) temperature increased. However, the as-prepared LPD-TiO2 films exhibited the most negative photopotential under both visible-light and white-light illumination. In conclusion, the as-prepared LPD-TiO2 films would provide the most effective photogenerated cathodic protection of 304SS.

2012-04-30

393

Fabrication and characterization of brookite-rich, visible light-active TiO2 films for water splitting  

Energy Technology Data Exchange (ETDEWEB)

We report that mild oxidation of Ti foils in air results in brookite-rich titanium oxide (TiO2) films with similar spectral response to that of dye-sensitized TiO2. X-ray powder diffraction and Raman spectroscopy show that the onset of brookite formation occurs at 500 8C, and the material is characterized by a strong absorption band in the visible spectral range. The first-principle calculations show that enhanced visible light absorption correlates with the presence of Ti interstitials. Photocurrent density measurements of water splitting reveal that the brookite-rich TiO2 exhibits the highest photocatalytic performance among the different forms of TiO2 produced by oxidation of Ti foils. With increasing oxidation temperature transformation to the rutile phase accompanied by declining visible range photoactivity is observed.

Pan, Hui [ORNL; Qiu, Xiaofeng [ORNL; Ivanov, Ilia N [ORNL; Meyer III, Harry M [ORNL; Wang, Wei [ORNL; Zhu, Wenguang [ORNL; Paranthaman, Mariappan Parans [ORNL; Zhang, Zhenyu [ORNL; Eres, Gyula [ORNL; Gu, Baohua [ORNL

2009-01-01

394

CdSe nanocrystal sensitized anatase TiO2 (001) tetragonal nanosheet-array films for photovoltaic application.  

UK PubMed Central (United Kingdom)

CdSe nanocrystal sensitized TiO2 nanosheet array heterostructure films were fabricated by a two-step method. Firstly, a single crystalline anatase TiO2 tetragonal nanosheet-array film on a transparent conductive fluorine-doped tin oxide (FTO) substrate was successfully prepared by hydrothermal method. Then, CdSe nanocrystalline sensitizers were deposited on the TiO2 nanosheet array by CBD method. The products were characterized with XRD, SEM, TEM and UV-vis absorption spectroscopy. The effect of the CdSe nanocrystal deposition time and the length of the TiO2 sheet on the photovoltaic performance of the resulting CdSe/TiO2 nanosheet array electrodes were also investigated. In comparison with the non-sensitized TiO2 nanosheet array, the photocurrent of CdSe sensitized TiO2 nanosheet has a great enhancement, which gives some insight to the fundamental mechanism of the performance improvement.

Feng S; Yang J; Liu M; Liu Y

2013-02-01

395

Analyses of surface coloration on TiO2 film irradiated with excimer laser  

International Nuclear Information System (INIS)

TiO2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm2. Microcracks at medium laser fluence of 1000 mJ/cm2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm2. The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO2 film might be used for adjustable filters.

2008-01-30

396

Thin films  

International Nuclear Information System (INIS)

This volume is a compilation of papers presented at the 1990 Spring Meeting of the Materials Research Society in a symposium entitled Thin Films: Stresses and Mechanical Properties II. As indicated by the title, the symposium was the second in a series, the first of which was held at the Fall Meeting in 1988. The importance of thin film mechanical properties is now recognized to the extent that basic characterization techniques such as microindentation and thin film stress measurement are performed routinely, and new characterization techniques are being developed on a daily basis. Many of the papers in the symposium dealt with the developments in these characterization methods and their application to a broad spectrum of materials such as compositionally modulated structures, ion implanted materials, optical coatings, and the numerous metals, ceramics and organics used in semiconductor device manufacture

1990-01-01

397

Deposition of graded TiO2 films featured both hydrophobic and photo-induced hydrophilic properties  

International Nuclear Information System (INIS)

Graded TiO2 films were deposited on unheated glass substrates by using a twin dc magnetron sputtering system. The graded TiO2 films showed a highly polycrystalline structure of anatase with a little rutile phases revealed by X-ray diffraction spectra. The surface energy of the fresh and UV irradiated films were evaluated by water contact angle measurement. The results indicated that the water contact angle of the fresh graded TiO2 films was found within 100-112 deg. The films then became a highly hydrophilic surface with the water contact angle of almost zero under 60 min UV irradiation. The XPS spectrum of Ti 2p revealed that the graded TiO2 films became a stoichiometric titanium oxide layer near the surface, proving that titanium was fully oxidized. It was found that the surface OH group density depended on the substrates employed for given sputtering conditions. In addition, AFM images revealed a considerably rough surface of the graded films with RMS roughness of 12.6-14.5 nm. One can conclude that the unique properties of highly hydrophobicity and photo-induced hydrophilicity can be attributed to fully oxidized chemical composition and higher roughness on the film surface.

2006-06-15

398

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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 obtenido 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.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 photocatalityc activity and efficiency with the physicochemical properties of the films.

Juan M Marín; José A Navío; Luis A Rios; Gloria Restrepo

2008-01-01

399

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 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 obtenido 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-pro (more) panol, 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 sys (more) tem 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 photocatalityc activity and efficiency with the physicochemical properties of the films.

Marín, Juan M; Navío, José A; Rios, Luis A; Restrepo, Gloria

2008-01-01

400