WorldWideScience
1

Mesoporous TiO2 thin films for photovoltaic applications  

OpenAIRE

Thin films of nanocrystalline, mesostructured titanium dioxide are very promising materials to build low cost and efficient photovoltaic devices. TiO2 present a high chemical stability and electronic properties such as photo-induced electronic transfer properties associated with the anatase phase. For many applications, highly porous nanostructured thin films with accessible pores are preferable to dense ones. Indeed, high accessible porosity leads to high surface area increasing the elec...

Dewalque, Jennifer; Cloots, Rudi; Mathis, Franc?ois; Henrist, Catherine

2008-01-01

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Superhydrophilicity of TiO2 nano thin films  

International Nuclear Information System (INIS)

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

3

Photocatalysis of sculptured thin films of TiO2  

International Nuclear Information System (INIS)

Enhanced surface reaction efficiency has been demonstrated in the photocatalysis of obliquely deposited TiO2 thin films with variously shaped columns such as zigzag, cylinder, and helix. The columnar thickness and spacing play an important role in the enhancement of the effective surface area, while the columnar shape is less important. The optimum morphology for a surface reaction has been obtained at the deposition angle ?=70 degree, where the photocatalytic activity is 2.5 times larger than that at ?=0 degree. The morphology controlled obliquely deposited thin films are applicable for solar cell, electro- and photochromic devices besides photocatalyst. [copyright] 2001 American Institute of Physics

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Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films  

International Nuclear Information System (INIS)

There are two nano-composite PMMA: TiO2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO2nanopowder and the second solution is nano-composite PMMA with self-prepared TiO2 powder. The self-prepared TiO2 powder is obtained by preparing the TiO2 sol-gel. Solvo thermal method were used to dry the TiO2 sol-gel and obtained TiO2 crystal. Ball millers were used to grind the TiO2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO2. Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO2 give high optical transparency than nano-composite PMMA with commercially available TiO2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO2 particles are occurred on the thin films and the surface roughness is increased when the thsurface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO2 with TiO2 nano powder compare to the other nano-composite solution. (author)

5

Thickness dependent activity of nanostructured TiO2/?-Fe2O3 photocatalyst thin films  

International Nuclear Information System (INIS)

The effect of thickness of TiO2 coating on synergistic photocatalytic activity of TiO2 (anatase)/?-Fe2O3/glass thin films as photocatalysts for degradation of Escherichia coli bacteria in a low-concentration H2O2 solution and under visible light irradiation was investigated. Nanograined ?-Fe2O3 films with optical band-gap of 2.06 eV were fabricated by post-annealing of thermal evaporated iron oxide thin films at 400 deg. C in air. Increase in thickness of the Fe2O3 thin film (here, up to 200 nm) resulted in a slight reduction of the optical band-gap energy and an increase in the photoinactivation of the bacteria. Sol-gel TiO2 coatings were deposited on the ?-Fe2O3 (200 nm)/glass films, and then, they were annealed at 400 deg. C in air for crystallization of the TiO2 and formation of TiO2/Fe2O3 heterojunction. For the TiO2 coatings with thicknesses ?50 nm, the antibacterial activity of the TiO2/?-Fe2O3 (200 nm) was found to be better than the activity of the bare ?-Fe2O3 film. The optimum thickness of the TiO2 coating was found to be 10 nm, resulting in about 70 and 250% improvement in visible light photo-induced antibacterial activity of the TiO2/?-Fe2O3 thin film as cO3 thin film as compared to the corresponding activity of the bare ?-Fe2O3 and TiO2 thin films, respectively. The improvement in the photoinactivation of bacteria on surface of TiO2/?-Fe2O3 was assigned to formation of Ti-O-Fe bond at the interface.

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Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping  

OpenAIRE

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 e...

Zhifeng Liu, Yun Wang

2012-01-01

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

OpenAIRE

We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control subs...

Francisco López-Huerta; Blanca Cervantes; Octavio González; Julián Hernández-Torres; Leandro García-González; Rosario Vega; Herrera-may, Agusti?n L.; Enrique Soto

2014-01-01

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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.

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PHOTOCATALYTIC PROPERTIES OF Cr DOPED TiO2–SiO2 NANOSTRUCTURE THIN FILM  

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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

2012-07-01

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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

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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

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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

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Growth of TiO2 thin film by reactive RF magnetron sputtering using oxygen radical  

International Nuclear Information System (INIS)

TiO2 thin films were deposited on MgO substrates by reactive RF magnetron sputtering using oxygen radicals. In order to perform the low temperature crystallization and control of crystal structure, the TiO2 thin film was irradiated by highly reactive oxygen radicals during the deposition. When the distance between the substrate and Ti-metal target (S-T distance) was 90 mm and substrate temperature were kept at 125 deg. C, the radical irradiated TiO2 film exhibited a (1 1 0) orientation with rutile structure. The radical irradiated TiO2 thin film prepared at 300 deg. C was changed from rutile to anatase structure by the adjustment of S-T distance. When the S-T distance was fixed at 110 mm, the TiO2 film exhibited a high a-axis orientation with anatase structure. The TiO2 rutile and anatase thin films consisted of small grains with very smooth surface

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TiO2 thin-films on polymer substrates and their photocatalytic activity  

International Nuclear Information System (INIS)

We have developed dip-coating process for TiO2-thin film on polymer substrates (acrylonitrile-butadiene-styrene polymer: ABS, polystyrene: PS). At first, a monodispersed and transparent TiO2 nano-sol solution was prepared by the controlled hydrolysis of titanium iso-propoxide in the presence of acetylacetone and nitric acid catalyst at 80 deg. C. Powder X-ray diffraction patterns of the dried particles are indicative of crystalline TiO2 with anatase-type structure. According to the XRD and transmission electron microscopy (TEM) studies, the mean particle size was estimated to be ca. 5 nm. The transparent thin films on ABS and PS substrates were fabricated by dip-coating process by changing the processing variables, such as the number of dip-coating and TiO2 concentration in nano-sol solution. Scanning electron microscopic (SEM) analysis for the thin film samples reveals that the acetylacetone-modified TiO2 nano-sol particles are effective for enhancing the interfacial adherence between films and polymeric substrates compared to the unmodified one. Photocatalytic degradation of methylene blue (MB) on the TiO2 thin-films has also been systematically investigated

15

Rutile TiO2 active-channel thin-film transistor using rapid thermal annealing  

Science.gov (United States)

TiO2 active-channel thin-film transistors (TFTs), in which the bottom-gate top-contact architecture was prepared with atomic layer deposition grown TiO2 as the semiconducting layer, were fabricated and then investigated based on key process parameters, such as the rapid thermal annealing (RTA) temperature. Structural analyses suggested that TiO2 films annealed at temperatures above 500 °C changed from an amorphous to a rutile phase. The TFT with a TiO2 semiconductor annealed at 600 °C exhibited strongly-saturated output characteristics, a much higher on/off current ratio of 4.3 × 105, and an electron mobility of 0.014 cm2/Vs. Moreover, the potential for manipulating TiO2-based TFTs with RTA methodology was demonstrated through the realization of a simple resistive-load inverter.

Kim, Sung-Jin; Heo, Kwan-Jun; Yoo, Su Chang; Choi, Seong Gon; Chang, Seung Wook

2014-10-01

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Development of multilayered nanocrystalline TiO2 thin films for photovoltaic application  

Science.gov (United States)

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

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

2014-04-01

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

OpenAIRE

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 successfu...

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

2008-01-01

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

International Nuclear Information System (INIS)

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

19

Application of Pcvd Process to Uniform Coating of TiO2 Thin Films on Polypropylene Beads  

Science.gov (United States)

The growth of the TiO2 thin films coated on the polypropylene beads was analyzed experimentally in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor. The precursors for the thin films were generated by plasma reactions, and they deposited on the polypropylene beads to become the uniform thin films. The TiO2 thin films grow more quickly on the polypropylene beads by increasing the mass flow rate of TTIP, or the rotation speed of the reactor. The smaller number of polypropylene beads in the reactor increases the growth rate of the thin films. The high-quality TiO2 thin films can be coated on particles uniformly by using the rotating cylindrical PCVD process. The particles coated with high-quality TiO2 thin films can be applied to the removal of air and water pollutants by a photodegradation reaction of TiO2.

Kim, Dong-Joo; Pham, Hung Cuong; Kim, Kyo-Seon

20

Preparation and Photocatalytic Activity of TiO2 Thin Films on Al Alloys  

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

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

2012-06-01

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Deposition of TiO2 thin films using atmospheric dielectric barrier discharge  

International Nuclear Information System (INIS)

In this paper the influence of precursor (titanium tetraisopropoxide (TTIP)) temperature, precursor and gas flow rates on the surface properties of TiO2 thin films deposited by atmospheric dielectric barrier discharge (ADBD) chemical vapour deposition (CVD) were investigated. Argon was used as working gas. Influence of O2 used as oxidizer was evaluated for determination of hydrophilicity of the films. Surface morphology of the thin TiO2 films deposited on glass substrates was studied by the atomic force microscopy (AFM) and water contact angle (CA) measurement. CA tests proved wettability improvement in experiments with oxygen addition

22

Magnetic and electrical properties of TiO2:Nb thin films  

International Nuclear Information System (INIS)

This study investigated the electrical and especially the magnetic properties of Niobium (Nb) doped TiO2 (TiO2:Nb) thin films. Experiments evidently present that both minimum of ferromagnetism and resistivity exist in a same Nb doping ratio (3.0%). The XPS experiments revealed that Nb doping simultaneously increases and compensates for oxygen vacancies. The proposed model explains magnetic and electrical properties by analyzing oxygen vacancies induced by vacuum annealing or by Nb doping.

23

XAS study of the local environment of impurities in doped TiO2 thin films  

CERN Document Server

In this work we present an X-ray Absorption Spectroscopy characterization of the local environment of the impurity in room temperature ferromagnetic anatase TiO2 thin films doped with Co, Ni, Cu, or Zn, deposited on LaAlO3 substrate by Pulsed Laser Deposition. It was found that there is a considerable amount of impurity atoms substituting Ti in TiO2 anatase, although the presence of metal transition monoxide clusters can not be discarded. From our results we infer that the observed room temperature ferromagnetism of the samples could be assigned to the metal transition atoms replacing Ti in TiO2 anatase.

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

2007-01-01

24

Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.  

Science.gov (United States)

Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained. PMID:25550120

Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

2015-01-01

25

Microwave Properties of Anatase and Rutile TiO2 Thin Films  

Science.gov (United States)

The dielectric properties of TiO2 thin films were investigated at microwave frequency range. Anatase, rutile, and its mixture phases were synthesized by RF magnetron sputtering. To measure dielectric constant and loss tangent, microstrip ring resonators were fabricated by silver deposition and photolithography. The unloaded quality factors and resonance frequencies of microstrip ring resonators were investigated. Thereafter, quality factors of TiO2 thin films were obtained considering the effects of conductor and fused silica substrate on total quality factors. Effective dielectric constants were also obtained from resonance frequencies. Quality factors and dielectric constants of TiO2 thin films decreased as the fraction of anatase phase increased. The effect of microstructures^1 such as crystal structure and strain on quality factors and dielectric constants will be discussed. ^1Appl. Phys. Lett. 76, 3043 (2000).

Oh, Jeongmin; Kim, Yongjo; Kim, Tae-Gon; Shin, Byungha; Lee, Sang Young; Park, Byungwoo

2001-03-01

26

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

27

Structural, electrical and optical properties of TiO 2 doped WO 3 thin films  

Science.gov (United States)

TiO 2 doped WO 3 thin films were deposited onto glass substrates and fluorine doped tin oxide (FTO) coated conducting glass substrates, maintained at 500 °C by pyrolytic decomposition of adequate precursor solution. Equimolar ammonium tungstate ((NH 4) 2WO 4) and titanyl acetyl acetonate (TiAcAc) solutions were mixed together at pH 9 in volume proportions and used as a precursor solution for the deposition of TiO 2 doped WO 3 thin films. Doping concentrations were varied between 4 and 38%. The effect of TiO 2 doping concentration on structural, electrical and optical properties of TiO 2 doped WO 3 thin films were studied. Values of room temperature electrical resistivity, thermoelectric power and band gap energy ( Eg) were estimated. The films with 38% TiO 2 doping in WO 3 exhibited lowest resistivity, n-type electrical conductivity and improved electrochromic performance among all the samples. The values of thermoelectric power (TEP) were in the range of 23-56 ?V/K and the direct band gap energy varied between 2.72 and 2.86 eV.

Patil, P. S.; Mujawar, S. H.; Inamdar, A. I.; Shinde, P. S.; Deshmukh, H. P.; Sadale, S. B.

2005-12-01

28

Mn-doped TiO2 thin films with significantly improved optical and electrical properties  

International Nuclear Information System (INIS)

TiO2 thin films with various Mn doping contents were fabricated by reactive magnetron sputtering deposition at 550 °C and their structural, optical and electrical properties were characterized. All films were made of densely packed columnar grains with a fibrous texture along the normal direction of the substrate. The as-deposited structure in the pure TiO2 film consisted of anatase grains with the [101] texture. Mn incorporation stabilized the rutile phase and induced lattice contraction in the [100] direction. The texture in the Mn-doped films changed from [110] to [200] with increasing Mn content. The incorporation of Mn in the TiO2 lattice introduced intermediate bands into its narrowed forbidden gap, leading to remarkable red-shifts in the optical absorption edges, together with significantly improved electrical conductivity of the thin films. Hall measurement showed that the incorporation of Mn-induced p-type conductivity, with hole mobility in heavily doped TiO2 (?40% Mn) being about an order higher than electron mobility in single-crystal rutile TiO2. Oxygen vacancies, on the other hand, interacted with substitutional Mn atoms to reduce its effect on optical and electrical properties.

29

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

2008-01-01

30

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 SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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 morpho [...] logy 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.

1706-17-01

31

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)

32

Uniform coating of TiO2 thin films on particles by rotating cylindrical PCVD reactor.  

Science.gov (United States)

We analyzed TiO2 thin film growth on glass particles in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor and numerically investigated the effects of several process variables on the film growth. An increase in titanium tetra-isopropoxide (TTIP) or O2 partial pressure can enhance the film growth rate on the particles because the concentration of TiO(x), which is the main precursor for thin film growth, becomes higher in the reactor. As the particle diameter decreases, the TiO(x) concentration increases and the thin film on the particles grows more quickly. The neutral-radical reaction between TTIP and O radicals for TiO(x) generation in TTIP + O2 plasmas can be important to enhance the thin film growth rate on the particles. The growth rate of TiO2 film predicted in this study was 1 approximately 20 nm/min, which is in good agreement with the published experimental results. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor. PMID:19916444

Kim, Dong-Joo; Baeg, Jin-Ook; Moon, Sang-Jin; Kim, Kyo-Seon

2009-07-01

33

Disinfection studies on TiO2 thin films prepared by a sol-gel method.  

Science.gov (United States)

Transparent anatase TiO2 nanometer thin films were prepared by dip-coating on soda-lime glass plates via the sol-gel method. The un-calcined and the calcined films were characterized by X-ray diffraction (XRD), AFM, Nano-indentation (hardness and Young's modulus), UV-vis spectrometry, thickness and hydrophilicity (contact angle measurements). The photocatalytic activity of the thin films was evaluated by performing disinfection studies on the Gram-negative microorganisms like Escherichia coli, and Staphylococcus Aureus, a Gram-positive organism. The photocatalytic activity for both groups of organisms was studied in saline and nutrient broth. The leakage of potassium from the bacteria was observed parallel to cell viability. The activity of the sol-gel prepared TiO2 thin films were compared under UV lamps and natural day light (ND) lamps with Degussa P-25 TiO2 thin films prepared on soda-lime glass using a polymer support and the commercial self-cleaning glass (SC). The sol-gel prepared thin films which were annealed at 450 degrees C, show highest photocatalytic activity, the slowest conversion rate from hydrophilic to a hydrophobic state, light-induced hydrophilicity, and also higher disinfection activities compared to P-25 films and commercial self-cleaning glass. The films also show excellent activities when continuously reused for more than a month. PMID:20055115

Kambala, Venkata Subba Rao; Naidu, Ravi

2009-02-01

34

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)

35

Optical Spectra of Graded Nanostructured TiO2 Chiral Thin Films  

CERN Document Server

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

36

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

Directory of Open Access Journals (Sweden)

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

Aytaç GÜLTEK?N

2014-02-01

37

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

OpenAIRE

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...

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

2013-01-01

38

Fe-Doped TiO2 Thin Films for CO Gas Sensing  

Science.gov (United States)

Fe-doped TiO2 thin films were prepared by the sol-gel technique on silicon substrate. The thin films were evaluated for detection of carbon monoxide (CO) gas at room temperature. The TiO2 films were characterized by x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, and ultraviolet-visible (UV) spectroscopy. The characterization revealed that, as the doping concentration was increased, the grain size decreased. XRD patterns revealed the phase transition from rutile to anatase with addition of different percentages (weight/volume) of Fe. The bandgap determined from UV spectroscopy was found to decrease with increasing Fe doping concentration. Fe doping was observed to have a significant effect on the resistivity of the doped TiO2 thin films. The gas sensing behavior of the films was studied by exposure to different concentrations of CO gas with measurement of the electrical resistance. It was observed that Fe-doped (7% weight/volume) TiO2 exhibited high sensitivity and good response/recovery on exposure to CO gas in the concentration range from 100 ppm to 900 ppm in Ar.

Kumar, Mukesh; Kumar, Dinesh; Gupta, Anil Kumar

2015-01-01

39

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

40

Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications  

OpenAIRE

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

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

2013-01-01

41

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

2013-02-01

42

Photocatalytic property of TiO2 thin films sputtered-deposited on unheated substrates  

International Nuclear Information System (INIS)

TiO2 films deposited on unheated substrates of alumina silicate glass by rf. (13.56 MHz) magnetron sputtering in the mixture of O2 and Ar gases have been studied with X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and optical spectroscopy. Structural and optical properties of TiO2 films deposited at different O2 concentrations and total pressures have been analyzed. Photocatalytic properties of TiO2 films were characterized by following the degradation of methylene blue molecules under UV irradiation. It was found that the rate of methylene blue decomposition strongly depends on morphology and crystallinity of the deposited films, namely on the content of the anatase phase and on the size of the anatase grains. The best photocatalytic activity was found on TiO2 films consisting of pure anatase phase with the size of grains of about 450 A. With the help of those films a thin film reactor for water purification has been designed and tested.

43

Structural Analysis of RF Sputtered TiO2 Thin Film on Cu Substrate for Various Annealing Temperatures  

Directory of Open Access Journals (Sweden)

Full Text Available The structural parameters of RF sputtered TiO2 thin film deposited on Cu substrates was tested using XRD spectra. Prepared TiO2 thin film was polycrystalline nature with the mixture of cubic, orthorhombic and tetragonal phases. Orthorhombic phase was preferentially grown on Cu substrate. The crystallite size of the TiO2 thin film was varied depends on the orientations and overall decreased crystallite size was noticed upto 300 °C. The observed residual stress was compressive nature as dominated at all temperature other than 400°C. Crystal defects such as dislocation density was high for cubic phase of TiO2 at higher annealing temperature. Overall, the annealing temperatures influenced the structural parameters with respect to the observed orientations of TiO2 thin film on Cu substrates.

Shanmugan S

2014-08-01

44

Investigation on sol-gel synthesized Ag-doped TiO2 cermet thin films  

International Nuclear Information System (INIS)

Undoped TiO2 and Ag-TiO2 (up to 23 at.% Ag) cermet thin films and polycrystalline powders have been prepared by sol-gel process. Their structure, composition, surface morphology and optical properties have been investigated by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and ultraviolet-visible spectroscopy (UV-VIS spectroscopy). It has been observed that while Ag does not form a solid solution with TiO2, it promotes the anatase to rutile phase transformation. The transformation temperature decreases from 827 deg. C for undoped TiO2 to about 650 deg. C for 23 at.% Ag-doped TiO2. SIMS analyses show that Ag is mostly present on the surface of the films. XPS studies confirm that these Ag are in the Ag0 state. Optical analyses show that with increasing Ag content, the refractive index (n) increases and the optical absorption behavior of the cermet films is modified, but the band gap of the anatase TiO2 is not influenced

45

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

OpenAIRE

In this study, pure and gold (Au) nanoparticles doped TiO2 thin films (Au/Ti = 10, 20, 30, 40 and 50 at%) were prepared by sol-gel method and the impact of Au nanoparticles doping on the optical, structural and morphological properties of these thin films was examined. All thin films were characterized using ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometry, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The optical band gap o...

Gu?lteki?n, Aytac?

2014-01-01

46

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

International Nuclear Information System (INIS)

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

47

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.

48

Dynamic Adsorption of Albumin on Nanostructured TiO2Thin Films  

OpenAIRE

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

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

2010-01-01

49

TiO2-based nanopowders and thin films for photocatalytical applications.  

Science.gov (United States)

TiO2-based nanopowders are elaborated by flame spray synthesis, FSS from organic precursors of titanium and chromium with the Cr content changing from 0 to 15 at.%. Well-crystallized nanopowders with high specific surface area SSA reaching 107 m2/g for undoped TiO2 and 177 m2/g for TiO2 + 15 at.% Cr are obtained. Thin films are deposited by rf reactive sputtering from metallic Ti and Ti-Cr targets in Ar + O2 flow controlled atmosphere. The adjustable area of Cr/Ti allows to obtain up to 16 at.% Cr in TiO2 thin films. X-ray diffraction, transmission electron spectroscopy, TEM, atomic force microscopy, AFM and optical spectrophotometry over the ultraviolet UV and visible VIS range of the light spectrum have been performed in order to characterize the nanomaterials. The particle size of nanopowders is within the range of 5-42 nm. Anatase is the predominating polymorphic form while the amount of rutile increases with Cr content to reach of about 25 wt.% at 15 at.% Cr. The post-deposition annealing of thin films in air at temperatures from 770 K to 1280 K modifies the phase composition, leads to irreversible transformation from anatase to rutile and affects the surface roughness. Structural and optical properties of TiO2-based nanopowders and thin films are compared. The effect of grain size and the level of chromium doping on the band gap E(g) is discussed. Photocatalytic activity of the nanopowders is tested for degradation of methylene blue, MB. PMID:20352753

Radecka, M; Rekas, M; Kusior, E; Zakrzewska, K; Heel, A; Michalow, K A; Graule, T

2010-02-01

50

Electrical properties of nanocrystalline TiO2 thin films doped with Tb and Pd  

International Nuclear Information System (INIS)

Transparent Oxide Semiconductors based on nanocrystalline thin films with desirable electrical and optical properties, are important in applications for transparent electronics. Such thin films can be applied, among others, as active layers in transparent transistors, UV photodiodes or solar cells. In this article, the presented subject of research are the thin films based on TiO2 doped with Tb and Pd. The thin films were deposited on glass and silicon substrates by the magnetron sputtering method. Structure of the TiO2:(Tb,Pd) thin films was investigated by the X-ray powder diffraction. Electrical measurements allowed the analysis of conduction mechanisms in fabricated thin films. From thermoelectrical characteristics conductivity, a type of electrical conduction, the activation energy and the Seebeck coefficient were determined. On the basis of current to voltage characteristics the power dependence I?Um was found for structures consisted of the thin films deposited on silicon. This behaviour indicates a conduction mechanism known as (SCLC). Additionally, from the temperature dependence of the current density, the trap concentration and the characteristic temperature were estimated.

51

Electrical properties of nanocrystalline TiO2 thin films doped with Tb and Pd  

Science.gov (United States)

Transparent Oxide Semiconductors based on nanocrystalline thin films with desirable electrical and optical properties, are important in applications for transparent electronics. Such thin films can be applied, among others, as active layers in transparent transistors, UV photodiodes or solar cells. In this article, the presented subject of research are the thin films based on TiO2 doped with Tb and Pd. The thin films were deposited on glass and silicon substrates by the magnetron sputtering method. Structure of the TiO2:(Tb,Pd) thin films was investigated by the X-ray powder diffraction. Electrical measurements allowed the analysis of conduction mechanisms in fabricated thin films. From thermoelectrical characteristics conductivity, a type of electrical conduction, the activation energy and the Seebeck coefficient were determined. On the basis of current to voltage characteristics the power dependence I~Um was found for structures consisted of the thin films deposited on silicon. This behaviour indicates a conduction mechanism known as (SCLC). Additionally, from the temperature dependence of the current density, the trap concentration and the characteristic temperature were estimated.

Domaradzki, J.; Sieradzka, K.; Kaczmarek, D.; Prociow, E.

2009-01-01

52

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.

Alexis Fischer

2013-03-01

53

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.

54

A non-labeled DNA biosensor based on light addressable potentiometric sensor modified with TiO2 thin film*  

OpenAIRE

Titanium dioxide (TiO2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO2 thin film by 3-aminopropyltriethoxysilane (APTS), fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO2 thin film. We found that, with UV irradiation, the si...

Zong, Xiao-lin; Wu, Chun-sheng; Wu, Xiao-ling; Lu, Yun-feng; Wang, Ping

2009-01-01

55

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

International Nuclear Information System (INIS)

Nb-doped TiO2 (TNO) has been widely explored as an alternative transparent conductor. TNO thin films have been fabricated by various deposition methods, and here we demonstrate fabrication by evaporation of sol–gel synthesized TNO source material. A range of NbxTi1?xO2 (x = 0, 0.03, 0.06, 0.12, 0.24) compositions were synthesized, pressed into pellets, and deposited as thin films via electron beam evaporation. The thin films were characterized for composition by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy and for crystallinity by X-ray diffraction for the different Nb contents explored. Transparency, conductivity, and Haacke transparent conductor figure of merit values are reported for the evaporated TNO films as a function of Nb content, substrate heating temperature, and post deposition annealing conditions. Glancing angle deposition (GLAD) is used to demonstrate nanostructuring of evaporated TNO based on physical shadowing. Nanostructured GLAD TNO films of increased morphological complexity can be produced using this method, and could lead to unique transparent conductor device architectures. - Highlights: ? Nb-doped TiO2 sol–gel materials were electron beam evaporated into thin films. ? Thin film Nb-content was correlated with sol–gel Nb-content. ? Transparency and conductivity were related to substrate temperature and Nb-content. ? Nanopillar Nb-doped TiO22 films were fabricated by glancing angle deposition.

56

Methylene blue photocatalytic mineralization under visible irradiation on TiO2 thin films doped with chromium  

Science.gov (United States)

We studied changes in structural, optical and photocatalytic properties of TiO2 thin films due to doping process with chromium. Powders of undoped TiO2 and chromium-doped TiO2 (Cr:TiO2) were synthesized by sol-gel method and, thin films were deposited by doctor blade method. The properties of the thin films were studied by X-ray diffraction (XRD), infrared spectroscopy (IR) and diffuse reflectance. The XRD patterns indicated that doping process changed the crystalline phases radio of TiO2 thin films, furthermore, the optical analysis showed that band gap value of Cr:TiO2 thin films was 31% fewer than undoped TiO2 thin films. Along, Langmuir-Hinshelwood model was used to obtain kinetic information of the photo-mineralization process; results indicated that photocatalytic activity of Cr:TiO2 thin films were four times better than undoped TiO2 thin films; finally the synergic effect was tested by addition of the H2O2, photocatalytic yield was improved from 26% to 61% when methylene blue photo-mineralization was assisted with slightly amount of H2O2.

Diaz-Uribe, Carlos; Vallejo, William; Ramos, Wilkendry

2014-11-01

57

Ellipsometric studies on TiO 2 thin films synthesized by spray pyrolysis technique  

Science.gov (United States)

TiO 2 thin films were synthesized on quartz substrates at substrate temperatures of 350 °C and 450 °C by thermal spray pyrolysis technique using titanium oxy-acetyl acetonate as a precursor. The optical properties of the thin films were characterized by a Spectroscopic Ellipsometer (SE). The surface morphology of the thin films was studied using Atomic Force Microscopy (AFM). The surface roughness values obtained using AFM and SE was compared. The refractive indices of the films were computed using a point by point ellipsometric data extraction procedure. The porosity of the films were modeled from the optical data by effective medium approximation and corroborated from empirical relations. Using Forouhi-Bloomer optical dispersion model, further treatment of SE data was carried out. The experimental investigations and modeling of the data were directed towards optical benchmarking of spray pyrolyzed titania thin films.

Sundari, S. Tripura; Raut, N. C.; Mathews, Tom; Ajikumar, P. K.; Dash, S.; Tyagi, A. K.; Raj, Baldev

2011-06-01

58

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

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

Microstructure and Transport properties of epitaxial VO2 thin films on TiO2 substrates  

Science.gov (United States)

Vanadium oxides are paradigms of strongly correlated oxides and have attracted attention because of the metal insulator transitions (MIT) that several of the oxides and sub-oxides exhibit. In particular, VO2 has a metal--semiconductor transition at 340 K. This transition in VO2 combines the properties of a pure Mott Hubbard electronic transition with those of a Peierls structural transition. The Mott transition is responsible for the extreme speed of the optical switching that has been observed (faster than 100 fs). Understanding this transition and how to control it remains a challenge for both theory and experimental physics. We used a novel deposition technique, Reactive Bias Target Ion Beam Deposition, to grow 40 nm epitaxial VO2 thin films on rutile TiO2 substrates with various crystal orientations. X-ray diffraction (XRD) was used to explore the epitaxy of VO2 and we found that all VO2 thin films on TiO2 substrates showed tetragonal symmetry at room temperature due to the constrain from rutile substrates. We also characterized the metal-insulator transition of VO2 films as the function of the crystal orientation of rutile TiO2. We also characterized the anisotropy of VO2 thin films. In collaboration with Kevin West and Stuart Wolf, University of Virginia.

Lu, Jiwei

2008-10-01

61

Preparation of rutile TiO 2 thin films by mist plasma evaporation  

Science.gov (United States)

Mist plasma evaporation (MPE) was developed to deposit TiO 2 thin films at atmospheric pressure using titanium chloride aqueous solution as precursor. The precursor was derived from BaCl 2 and Ti(SO 4) 2 source materials, and was ultrasonically nebulized into fine droplets. The droplets were transported by Ar and O 2 mixed carrier gas to inductively coupled plasma generated at atmospheric pressure. The source materials were evaporated by the high temperature of the plasma, and then deposited on the substrates heated by the plasma. The phase and morphology of the films were apparently affected by the flow rate of O 2. It was found that sufficient oxidation atmosphere in deposition was necessary to prepare stoichiometric TiO 2 thin films. The films deposited at 966 K with sufficient O 2 introduced in the plasma were rutile TiO 2, and showed smooth and dense microstructure. The deposition mechanism of MPE was of clusters deposition, and the initial clusters deposition process of the film was observed.

Huang, Hui; Yao, Xi

2004-08-01

62

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)

63

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

International Nuclear Information System (INIS)

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

64

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

65

Preparation of titanium dioxide porous thin films via photopolymerization of the colloidal TiO2 dispersion  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films with porous structures have been successfully achieved by photopolymerization stimulating the particle dispersion combined TiO2 colloid with photoinitiator and monomer. The photopolymerization monomer Pentaerythritol Triacrylate (PETA) and photoinitiator 2-Hydroxy-2-methyl-propiophenone (HMPP) are added to the TiO2 colloidal solution to form the new colloidal TiO2 dispersion. After coating the dispersion on the substrate, the coating is cured with UV light. With the evaporation of solvent and the formation of microgels induced by polymerization, a phase separation occurs in the system. A porous TiO2 film with various pore sizes from mesoporous to macroporous could be produced after heat treatment. The morphology and size of pores could be tuned by changing the process of phase separation, which is controlled by the composition of colloidal TiO2 dispersion. The content of photoinitiator and the temperature of heat treatment were decided by UV–vis absorption spectra and thermal analysis (DTA–TGA), respectively; Real-Time Fourier-transform infrared (RT-FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HR-TEM) were used to characterize the TiO2 films. The as-prepared TiO2 porous films exhibited higher photocatalytic activity for degradation methylene blue in comparison with conventional TiO2 dense film due to its porous structure. - Highlights: • TiO2 porous film was prepared by photopolymerization stimulating particle dispersion. • Colloidal TiO2 dispersion contained photoinitiator and monomer for curing reaction. • The morphology and size of pores were dependent on the composition of dispersion. • The phase separation mechanism occurred during the photopolymerization was proposed. • TiO2 porous films showed high photocatalytic activity

66

Optical properties of TiO2 thin films deposited on polycarbonate by ion beam assisted evaporation  

International Nuclear Information System (INIS)

TiO2 thin films were deposited on polycarbonate (PC) substrate by ion beam assisted evaporation. The grain size increased with the ion anode voltage and film thickness. The TiO2 thin films had an amorphous structure. Moire deflectometry was used to measure the nonlinear refractive indices of TiO2 thin films on PC substrates. The nonlinear refractive index was measured to be of the order of 10-8 cm2 W-1 and a change in refractive index was of the order of 10-5. Dense TiO2 films exhibited high linear refractive indices, red-shift of the optical absorbance, and absorbance in the near-IR region.

67

Synthesis and hydrophilic properties of Mo doped TiO2 thin films  

Science.gov (United States)

Amorphous undoped TiO2 and Mo-doped TiO2 thin films were obtained by spray pyrolysis. By heat treatment, they became polycrystalline consisting in anatase, or mixed anatase/rutile phases, if deposited on glass or silicon, respectively. Mo enters in the TiO2 matrix as Mo5+, determining a slight red shift of the absorption edge. Based on Fourier transmission infrared analysis, performed on the studied films, before and after irradiation, providing information on the relationship between hydrophilicity and the amount of the adsorbed hydroxyl groups, we certify once again that the anatase phase (present in proportion of 100% in the films deposited on glass) is superior concerning the hydrophilic properties. Mo enhances wettability for the films deposited on silicon, compared to the undoped one, even if determines a rise in the rutile weight percentage, as a combined effect with the substrate nature. The decomposition of the oleic acid confirms that titania films with higher hydrophilic performances are also good photocatalysts, confirming in fact that investigating the hydrophilic properties of these films constitutes a much simpler way to obtain information on their photocatalytic activity.

Mardare, Diana; Cornei, Nicoleta; Luca, Dumitru; Dobromir, Marius; Irimiciuc, ?tefan A.; Pung?, Luciana; Pui, Aurel; Adomniţei, C?t?lin

2014-06-01

68

Synthesis and characterization of TiO2 thin films coated on metal substrate  

International Nuclear Information System (INIS)

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

69

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

70

Pyrosol deposition of anatase TiO2 thin films starting from Ti(OiPr)4/acetylacetone solutions  

OpenAIRE

TiO2 thin films were deposited on Si(100) and steel substrates by Pyrosol technique. The layer morphology depends on the concentration of titanium tetra-isopropoxide (TTIP) used as molecular precursor in solutions with acetylacetone (Acac). The concentration and, as a result, the viscosity of these TTIP/Acac starting solutions plays an important role on the efficiency of their nebulization and, consequently, on the microstructure and the growth kinetics of the TiO2 thin films. The correlation...

Duminica, Florin-daniel; Maury, Francis; Abisset, Sidonie

2007-01-01

71

Fe ion-implanted TiO2 thin film for efficient visible-light photocatalysis  

Science.gov (United States)

This work shows the application of metal ion-implantation to realize an efficient second-generation TiO2 photocatalyst. High fluence Fe+ ions were implanted into thin TiO2 films and subsequently annealed up to 550 °C. The ion-implantation process modified the TiO2 pure film, locally lowering its band-gap energy from 3.2 eV to 1.6-1.9 eV, making the material sensitive to visible light. The measured optical band-gap of 1.6-1.9 eV was associated with the presence of effective energy levels in the energy band structure of the titanium dioxide, due to implantation-induced defects. An accurate structural characterization was performed by Rutherford backscattering spectrometry, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and UV/VIS spectroscopy. The synthesized materials revealed a remarkable photocatalytic efficiency in the degradation of organic compounds in water under visible light irradiation, without the help of any thermal treatments. The photocatalytic activity has been correlated with the amount of defects induced by the ion-implantation process, clarifying the operative physical mechanism. These results can be fruitfully applied for environmental applications of TiO2.

Impellizzeri, G.; Scuderi, V.; Romano, L.; Sberna, P. M.; Arcadipane, E.; Sanz, R.; Scuderi, M.; Nicotra, G.; Bayle, M.; Carles, R.; Simone, F.; Privitera, V.

2014-11-01

72

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 highericans 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.

73

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

Directory of Open Access Journals (Sweden)

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

Mehrnoush Mokhtarimehr

2013-07-01

74

EFFECT OF ISOTHERMAL ANNEALING ON PROPERTIES OF TiO2 THIN FILMS TOWARDS MOS CAPACITOR APPLICATIONS  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of isothermal annealing on structural and electrical properties of TiO2 thin films has been investigated. The TiO2 thin films were deposited at 350 ?C using spray pyrolysis technique. The structural studies were carried out using XRD and Raman spectroscopy. The electrical characteristics were studied on the fabricated MOS structure and the parameters such as ideality factor, saturation current density and zero bias barrier height were obtained. It was found that isothermal annealing has improved the structural as well as electrical parameters of TiO2 compared to the values predicted in literature.

H D CHANDRASHEKARA

2014-04-01

75

Electron-Stimulated Oxidation of Thin Water Films Adsorbed on TiO2(110)  

Energy Technology Data Exchange (ETDEWEB)

Electron-stimulated reactions in thin (< 3 monolayer, ML) water films adsorbed on TiO2(110) are investigated. For electron fluences less than ~1×1016 e-/cm2, irradiation with 100 eV electrons results in electron-stimulated desorption (ESD) of atomic and molecular hydrogen, but no measurable O2. The ESD leaves adsorbed hydroxyls which oxidize the TiO2(110) surface and change the post-irradiation TPD spectra of the remaining water in characteristic ways. The species remaining on the TiO2(110) after irradiation of adsorbed water films are apparently similar to those produced without irradiation by co-dosing water and O2. Annealing above ~600 K reduces the oxidized surfaces, and water TPD spectra characteristic of ion sputtered and annealed TiO2(110) are recovered. The rate of electron-stimulated “oxidation” of the water films is proportional to the coverage of water in the first layer for coverages less than 1 ML. However, higher coverages suppress this reaction. When thin water films are irradiated, the rate of electron-stimulated oxidation is independent of the initial oxygen vacancy concentration, as is the final oxidized state achieved at high electron fluences. To explain the results, we propose that electron excitation of water molecules adsorbed on Ti4+ sites leads to desorption of hydrogen atoms and leaves an OH adsorbed at the site. If hydroxyls are present in the bridging oxygen rows, these react with the OH’s on the Ti4+ sites to reform water and heal the oxygen vacancy associated with the bridging OH. Once the bridge bonded hydroxyls have been eliminated, further irradiation increases the concentration of OH’s in the Ti4+ rows leading to the creation of species which block sites in the Ti4+ rows, perhaps H2O2 and/or HO2.

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

2007-11-08

76

Enhanced photocatalytic activities of Ta, N co-doped TiO2 thin films under visible light  

International Nuclear Information System (INIS)

Ta, N co-doped TiO2 thin films in an anatase form were fabricated by radio-frequency (RF) magnetron sputtering method, and their photoelectrochemical and photocatalytic properties were compared to those of non-doped TiO2 and N-doped TiO2 thin films. The incident photon-to-current conversion efficiency (IPCE) spectra indicated the suppression of the isolated N 2p band formation but the enhancement hybridization of valence band with N 2p band in Ta, N co-doped TiO2, compared to N-doped TiO2. The changes in IPCE spectra in the presence of reductants, such as SCN-, Br- and I-, clearly proved that the holes produced in the N 2p band of Ta, N co-doped TiO2 under visible light had higher oxidation power than those of N-doped TiO2. Moreover, it was shown that the photocatalytic oxidation activity evaluated by the oleic acid decomposition and photoinduced hydrophilic conversion were enhanced by the Ta, N co-doping under visible light, when compared to N single doping. The enhancement of photocatalytic performances by the Ta, N co-doping under visible light was also supported by the first principle calculation, indicating the positive shift of the N 2p band in Ta, N co-doped TiO2, compared to N-doped TiO2

77

Thin Functional Films of TiO2 Nanoparticles  

OpenAIRE

Magnetron Sputtering and the Modulated Hollow Cathode Plasma Jet Sputtering. As chemical method the sol-gel process carried out in the templating environment as dip-coating and piezo-jet printing was employed. The produced films differed in many structural characteristics and also in their photoelectrochemical behaviour, as the primary sought function. The produced layers were described by means of atomic force microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron s...

Morozova?, Magdalena

2011-01-01

78

Theoretical and experimental characterization of TiO2 thin films deposited at oblique angles  

International Nuclear Information System (INIS)

The microstructural features of amorphous TiO2 thin films grown by the electron beam physical vapour deposition technique at oblique angles have been experimentally and theoretically studied. The microstructural features of the deposited films were characterized by considering both the column tilt angle and the increase in the column thickness with height. A Monte Carlo model of film growth has been developed that takes into account surface shadowing, short-range interaction between the deposition species and the film surface, as well as the angular broadening of the deposition flux when arriving at the substrate. The good match between simulations and experimental results indicates the importance of these factors in the growth and microstructural development of thin films deposited at oblique angles.

79

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

OpenAIRE

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 at...

Ghrairi, Najla; Bouaicha, Mongi

2012-01-01

80

Optimization of experimental parameters in preparing multinanoporous TiO2 thin films by the anodic oxidation method  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The anodic oxidation method has been applied to the preparation of multinanoporous TiO2 thin films. The experimental parameters, including the electrolyte nature, oxidation voltage, and oxidation time have been carefully controlled. Their influence on the structure, morphology and photocatalytic act [...] ivity of the prepared TiO2 films has been evaluated by measuring the current density. The result showed that there was a relatively wide range of preparation conditions, and the internal relationship between the structure and the photocatalytic properties of the TiO2 films was analyzed.

Gracien B., Ekoko; Joseph K-K., Lobo; Omer M., Mvele; Antoine K., Mbongo; Jérémie L., Muswema; Clarisse Z., Lefuni.

2013-08-01

81

Room temperature growth of nanocrystalline anatase TiO2 thin films by dc magnetron sputtering  

International Nuclear Information System (INIS)

We report, the structural and optical properties of nanocrystalline anatase TiO2 thin films grown on glass substrate by dc magnetron sputtering at room temperature. The influence of sputtering power and pressure over crystallinity and surface morphology of the films were investigated. It was observed that increase in sputtering power activates the TiO2 film growth from relative lower surface free energy to higher surface free energy. XRD pattern revealed the change in preferred orientation from (1 0 1) to (0 0 4) with increase in sputtering power, which is accounted for different surface energy associated with different planes. Microstructure of the films also changes from cauliflower type to columnar type structures with increase in sputtering power. FESEM images of films grown at low pressure and low sputtering power showed typical cauliflower like structure. The optical measurement revealed the systematic variation of the optical constants with deposition parameters. The films are highly transparent with transmission higher than 90% with sharp ultraviolet cut off. The transmittance of these films was found to be influenced by the surface roughness and film thickness. The optical band gap was found to decrease with increase in the sputtering power and pressure. The refractive index of the films was found to vary in the range of 2.50-2.24 with increase in sputtering pressure or sputtering power, resulting in the possibility of producing TiOg in the possibility of producing TiO2 films for device applications with different refractive index, by changing the deposition parameters.

82

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

International Nuclear Information System (INIS)

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

83

Gas sensing properties of very thin TiO2 films prepared by atomic layer deposition (ALD)  

Science.gov (United States)

Very thin titanium dioxide (TiO2) films of less than 10 nm were deposited by atomic layer deposition (ALD) in order to study their gas sensing properties. Applying the quartz crystal microbalance (QCM) method, prototype structures with the TiO2 ALD deposited thin films were tested for sensitivity to NO2. Although being very thin, the films were sensitive at room temperature and could register low concentrations as 50-100 ppm. The sorption is fully reversible and the films seem to be capable to detect for long term. These initial results for very thin ALD deposited TiO2 films give a promising approach for producing gas sensors working at room temperature on a fast, simple and cost-effective technology.

Boyadjiev, S.; Georgieva, V.; Vergov, L.; Baji, Zs; Gáber, F.; Szilágyi, I. M.

2014-11-01

84

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.

2001-01-01

85

TiO2 thin film growth using the MOCVD method  

Scientific Electronic Library Online (English)

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

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

2001-07-01

86

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

OpenAIRE

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

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

1990-01-01

87

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

International Nuclear Information System (INIS)

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

88

Fabrication and evaluation of TiO2/graphite silica bilayer thin films prepared by laser ablation method  

International Nuclear Information System (INIS)

The bilayer thin film composed of graphite silica (GS) and TiO2 was prepared by the laser ablation technique. The properties of the thin films considerably depended on the laser ablation conditions such as gas pressure and substrate temperature in a chamber. The laser ablation of GS caused complete disappearance of the quartz XRD (X-ray diffraction) peaks in GS. The GS loading, especially at a thickness of around 200 nm, led to significant enhancement in the photocatalytic activity of the TiO2 thin film for the hydrogen production and the methylene blue decomposition in spite of the destruction of the quartz crystal in GS

89

TiO2 thin films prepared via adsorptive self-assembly for self-cleaning applications.  

Science.gov (United States)

Low-cost controllable solution-based processes for preparation of titanium oxide (TiO(2)) thin films are highly desirable, because of many important applications of this oxide in catalytic decomposition of volatile organic compounds, advanced oxidation processes for wastewater and bactericidal treatments, self-cleaning window glass for green intelligent buildings, dye-sensitized solar cells, solid-state semiconductor metal-oxide solar cells, self-cleaning glass for photovoltaic devices, and general heterogeneous photocatalysis for fine chemicals etc. In this work, we develop a solution-based adsorptive self-assembly approach to fabricate anatase TiO(2) thin films on different glass substrates such as simple plane glass and patterned glass at variable compositions (normal soda lime glass or solar-grade borofloat glass). By tuning the number of process cycles (i.e., adsorption-then-heating) of TiO(2) colloidal suspension, we could facilely prepare large-area TiO(2) films at a desired thickness and with uniform crystallite morphology. Moreover, our as-prepared nanostructured TiO(2) thin films on glass substrates do not cause deterioration in optical transmission of glass; instead, they improve optical performance of commercial solar cells over a wide range of incident angles of light. Our as-prepared anatase TiO(2) thin films also display superhydrophilicity and excellent photocatalytic activity for self-cleaning application. For example, our investigation of photocatalytic degradation of methyl orange indicates that these thin films are indeed highly effective, in comparison to other commercial TiO(2) thin films under identical testing conditions. PMID:22260264

Xi, Baojuan; Verma, Lalit Kumar; Li, Jing; Bhatia, Charanjit Singh; Danner, Aaron James; Yang, Hyunsoo; Zeng, Hua Chun

2012-02-01

90

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

International Nuclear Information System (INIS)

Full text: TiO2 exists in three different polymorphs such as anatase, rutile and brookite. The anatase phase is stable at low temperatures (upto 600 deg C) and rutile structure is stable at high temperatures (700 - 800 deg C). The anatase TiO2 thin films have applications in dye sensitized solar cells (DSSCs) and photocatalysis. TiO2 thin films were prepared using RF magnetron sputtering at room temperature. As prepared thin films were amorphous in nature and ex-situ air and oxygen annealed thin films at 500 deg C for 2 H show anatase crystallinity. The structural and morphological studies of the thin films were performed by X-ray diffraction, Raman spectroscopy and Atomic Force Microscopy (AFM). The optical properties of thin films were studied by UV-Visible spectra. The nanocrystalline TiO2 thin films were transparent in visible region (maximum ?83% for oxygen annealed and 0.03 mbar Ar pressure). The thin films annealed in air show larger crystallite size than oxygen annealed thin films. This was also confirmed by Raman, AFM and band gap calculations. The band gap of the oxygen annealed thin films were greater compared to that of air annealed thin films due to smaller crystallite size. The direct hand gap of thin films were calculated and found to be in the range 3.8 - 3.9 eV. The increase in hand gap as the crystallite size decreases indicates size dependent quantum confinement effect. The nano crystalline TiO22 thin film with such a higher band gap (3.9 eV) will be used as a buffer layer in hybrid DSSCs and also as an anode in DSSCs. Results will be presented in detail

91

Alcohol Sensing Properties of Sol-gel Derived TiO2 Thin Film  

Science.gov (United States)

In this work, alcohol sensing properties of pure TiO2 thin film were investigated. TiO2 were deposited on glass substrate patterned with interdigitated transducer (IDT) by a sol-gel dipping method. Precursor solution is prepared by dissolving of titanium(IV) n-butoxide in methanol. Then glacial acetic acid was added into the solution. Final heating was performed at 773 K in air. Crystal structure of the film was investigated using X-ray diffraction. Target gases were vapors of ammonia, methanol, ethanol, and isopropyl alcohol. The measurements were performed in the temperature range of 293 K and 523 K. Gas concentrations were kept in the range of 0.4%-18%. Response characteristics of the film were determined by means of change in dc conductivity as a function of gas concentration and temperature. During the measurements 1 volt was applied to the IDT. Gas concentrations were controlled by mass flow controller. The film showed good sensitivity to the target gases in the measurement range. The results showed that responses of the film were reversible and depend on the operating temperature and gas concentration.

Dumludag, Fatih; Bulut, Sevinc; Altindal, Ahmet

2010-01-01

92

Thin nanostructured crystalline TiO 2 films and their applications in solar cells  

OpenAIRE

Forschung an dünnen, kristallinen TiO2-Filmen hat wegen der faszinierenden physikalischen Eigenschaften beachtenswertes Interesse auf sich gezogen. Nanostrukturierte TiO2-Filme spielen eine wichtige Rolle in der auf TiO2 basierenden Farbstoff-Sensibilisierten Solarzelle, da sie als Substrat für die Adsorption der Farbstoffmoleküle und als Matrix für den Elektronentransport fungieren können. Sie haben daher großen Einfluss auf die Arbeitsleistung der Solarzelle. Folglich ist die Kontroll...

Cheng, Yajun

2007-01-01

93

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

2013-01-01

94

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

Directory of Open Access Journals (Sweden)

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

Young-Hee Joo

2012-06-01

95

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.

96

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

OpenAIRE

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. (c) 2009 Elsevier B.V. All rights reserved.

Ivanova, T.; Harizanova, A.; Koutzarova, T.; Krins, Natacha; Vertruyen, Be?ne?dicte

2009-01-01

97

Strain analysis of photocatalytic TiO2 thin films on polymer substrates  

International Nuclear Information System (INIS)

Titania (TiO2) thin films have been deposited on polymer sheets by magnetron sputtering at room temperature. Previous X-ray diffraction experiments revealed, for a wide range of deposition parameters, that the as-deposited titania thin films are predominantly amorphous; however, Raman scattering experiments revealed small traces of crystalline phases. The photocatalytic behaviour of the titania coatings was determined by combined ultra-violet (UV) irradiation and absorption measurements of a chosen dye (pollutants) in the presence of this catalyst. In order to assess the mechanical behaviour of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. As the system was stretched, cracks transverse to the loading direction developed in the film. The number of cracks increased as the applied strain increased, thus the relation between the measured crack density and the applied strain has been used to characterize the film strength and has also been correlated with the film photocatalytic efficiency. As a result of moderate fissuring on the titania film, it was found that for strain deformations up to 5% the photocatalytic activity is enhanced due to the exposure of more catalyst surface area for the pollutant to be adsorbed and subsequently dissociated upon UV illumination

98

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

Science.gov (United States)

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

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

2012-03-01

99

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

International Nuclear Information System (INIS)

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

100

TiO2 thin films (1 µm) with ordered porosity used as high performance photoelectrode in DSSC  

OpenAIRE

Mesoporous anatase thin films are very promising materials to act as electrode in dye-sensitized solar cells. Randomly oriented nanocrystalline TiO2 particles are usually used to prepare photoelectrodes with a thickness of 10-15 µm. Templated-assisted dip-coating techniques are used to obtain thin films with ordered porosity. The use of different templates influences the film porosity in terms of long-range order, percentage of porosity, pore size and pores connectivity. The photovoltaic per...

Dewalque, Jennifer; Cloots, Rudi; Dubreuil, Olivier; Krins, Natacha; Henrist, Catherine

2010-01-01

101

Nano-scaled photocatalytic TiO2 thin films prepared by magnetron sputtering  

International Nuclear Information System (INIS)

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

102

Nanostructured TiO2/carbon nanosheet hybrid electrode for high-rate thin-film lithium-ion batteries  

Science.gov (United States)

Heterogeneous nanostructured electrodes using carbon nanosheets (CNS) and TiO2 exhibit high electronic and ionic conductivity. In order to realize the chip level power sources, it is necessary to employ microelectronic compatible techniques for the fabrication and characterization of TiO2-CNS thin-film electrodes. To achieve this, vertically standing CNS grown through a catalytic free approach on a TiN/SiO2/Si substrate by plasma enhanced chemical vapour deposition (PECVD) was used. The substrate-attached CNS is responsible for the sufficient electronic conduction and increased surface-to-volume ratio due to its unique morphology. Atomic layer deposition (ALD) of nanostructured amorphous TiO2 on CNS provides enhanced Li storage capacity, high rate performance and stable cycling. The amount of deposited TiO2 masks the underlying CNS, thereby controlling the accessibility of CNS, which gets reflected in the total electrochemical performance, as revealed by the cyclic voltammetry and charge/discharge measurements. TiO2 thin-films deposited with 300, 400 and 500 ALD cycles on CNS have been studied to understand the kinetics of Li insertion/extraction. A large potential window of operation (3-0.01 V); the excellent cyclic stability, with a capacity retention of 98% of the initial value; and the remarkable rate capability (up to 100 C) are the highlights of TiO2/CNS thin-film anode structures. CNS with an optimum amount of TiO2 coating is proposed as a promising approach for the fabrication of electrodes for chip compatible thin-film Li-ion batteries.

Moitzheim, S.; Nimisha, C. S.; Deng, Shaoren; Cott, Daire J.; Detavernier, C.; Vereecken, P. M.

2014-12-01

103

Thin films of photocatalytic TiO2 and ZnO deposited inside a tubing by spray pyrolysis  

International Nuclear Information System (INIS)

Thin films of photocatalytic TiO2 and ZnO were deposited in Vycor tubing by a simple and reproducible spray pyrolysis technique. Films were transparent and non-light scattering. Film characterization by transmission electron microscopy shows that titanium oxide films were polycrystalline and that their structure corresponded to the tetragonal anatase phase. In addition, ZnO films were polycrystalline with a structure that belonged to the hexagonal Wurtzite type. The solar photocatalytic efficiency for butane degradation was compared to that of Degussa P-25 TiO2 powder (P-25). Reaction rate and reaction order were obtained from butane concentration measurements using the tubing as a non-circulating reactor exposed to solar radiation. The best fitting was obtained for a pseudo-first order rate constant. The TiO2-covered tubing shows very high photocatalytic activity, even higher than that of P-25, if activity per unit of catalyst mass is considered

104

Photocatalytic investigations of TiO2-P25 nanocomposite thin films prepared by peroxotitanic acid modified sol-gel method  

Science.gov (United States)

TiO2 thin films and TiO2-P25 nanocomposite thin films were synthesized by sol-gel method utilizing peroxotitanic acid sol (PTA). Films were obtained by three dip coatings of sol on borosilicate glasses. The crystalline size and the variation in phase of thin films were determined through X-ray diffraction. The average crystalline size of the films that was in the range of 42 nm showed a reduction in the value by increasing the rutile content. The surface morphology of the films has been characterized utilizing Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Contact-mode atomic force microscopy (AFM). The results of the morphological investigations were completely coincided with the formation of TiO2-P25 nanocomposite. The optical property of the films has been evaluated by Diffuse Reflection Spectrophotometer (DRS) at the room temperature. The obtained UV-vis spectra for both TiO2 and TiO2-P25 thin films had similar maximum wavelengths. The band gap values for the direct and indirect transitions have been measured for the TiO2 and TiO2-P25 thin films and the results showed negligible variations. The photocatalytical activity of the films was studied by photodegradation of Reactive Red 222 (RR222) under UV irradiation. The results showed that the photocatalytic efficiency of TiO2-P25 nanocomposite thin films had enhanced by the addition of rutile phase which was obviously due to the cooperation of TiO2 and P25 nanoparticles in effective charge transfer process. Additionally, photodegradation rate constant result calculations for the TiO2-P25 nanocomposite thin films can well exhibit the increase in its photocatalytic performance in comparison with TiO2 thin films.

Oshani, Fatemeh; Marandi, Reza; Rasouli, Sousan; Farhoud, Mitra Keramati

2014-08-01

105

Optical and hydrophilic properties of Cr doped TiO2-SiO2 nanostructure thin film  

International Nuclear Information System (INIS)

Cr doped TiO2-SiO2 nanostructure thin film on glass substrates was prepared by a sol-gel dip coating process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and chemical properties of the films. A UV-vis spectrophotometer was used to measure the transmittance spectra of the thin film. The hydrophilicity of the thin film during irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicated that Cr doping has a significant effect on the transmittance and super-hydrophilicity of TiO2-SiO2 thin film.

106

Mesoporous TiO2 thin films embedded with Au nanoparticles for the enhancement of the photocatalytic properties  

International Nuclear Information System (INIS)

Mesoporous TiO2 thin films were prepared by hydrothermal-oxidation of titanium metal thin films, which were obtained by DC magnetron sputtering technique. Gold nanoparticles, which were prepared by reduction of HAuCl4, were embedded into the holes of the mesoporous TiO2 films by capillary method followed by annealing in air up to 400 oC. The size of pore of TiO2 films is about 100 nm and that of Au nanoparticles is about 10 nm in average. The morphology of the films was analyzed by field emission scanning electron microscope (FE-SEM) and scanning probe microscopes (SPMs). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of methylene blue solution are discussed. The obtained results show that the dispersion of Au nanoparticles on the mesoporous TiO2 matrix will help enhancing the photocatalytic activity with respect to pure TiO2 under visible light irradiation.

107

Contact Angle of TiO2/SnO2 Thin Films Coated on Glass Substrate  

Directory of Open Access Journals (Sweden)

Full Text Available The self-cleaning effect in terms of contact angle value and photocatalytic activity of TiO2 and TiO2/SnO2 thin films coated on glass substrate was measured. The thin films were prepared using a sol-gel dip coating technique and calcinated at a temperature of 500 °C for 2 h with a heating rate of 10 °C/min. The microstructures of the fabricated thin films were characterized by SEM and XRD techniques. The photocatalytic properties of the thin films were also tested via the degradation of methylene blue (MB solution under UV irradiation. Finally, the self-cleaning properties of the thin films were evaluated by measuring the contact angle of water droplets on the thin films with and without UV irradiation. It was found that 1 %mol SnO2/TiO2 thin films showed the highest of photocatalytic activity and provided the most self-cleaning properties.doi:10.14456/WJST.2014.21

Weerachai SANGCHAY

2014-05-01

108

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

109

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

110

Effect of annealing temperature on Binary TiO2:SiO2 nanocrystalline thin films  

International Nuclear Information System (INIS)

Binary TiO2:SiO2 nanocrystalline thin films were prepared using liquid phase deposition at 35 .deg. C and annealed in air at temperatures ranging from 100 .deg. C to 500 .deg. C. The microstructural and the optical properties of the thin films were characterized by using an ultraviolet-visible spectrophotometer, a Fourier transform infrared spectrophotometer, a scanning electron microscope, and a transmission electron microscope. The photocatalytic performance of the thin films was evaluated by using photocatalytic degradation of methylene blue. The results showed that most TiO2 nanocrystallites were uniformly dispersed onto an amorphous SiO2 matrix and that nanopores had been formed on top of the TiO2 nanoparticles, resulting in an improved photocatalytic efficiency due to an increase number of effective adsorption sites. As we increased the annealing temperature, the small crystallites progressively aggregated into larger clusters, reducing the specific surface area of the TiO2 nanocrystallites. Moreover, SiO2 nanopowders moved towards the surface and covered the TiO2, resulting in a decreased photocatalytic activity.

111

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

International Nuclear Information System (INIS)

Full text: Considerable research is being carried out on dye-sensitised solar cells, the most extensively studied of which are based on a nanostructured titania semiconducting film deposited on a conducting glass substrate. The preparation of cross-sections of these films is essential for investigating of the shape, size and distribution of the TiO2 particles by TEM. In the present work, we have used a relatively simple and rapid procedure involving ultramicrotomy to prepare cross-sections of the films for initial TEM examination. Titania thin films were produced by screen-printing a nanoparticle titania paste onto SnO2-coated glass substrates, followed by heating in air at 500 deg C for 1 hour. The nanoporous films are optically transparent, have a high surface area, and are 7 to 8 ?m thick. The thickness could be checked with a confocal laser scanning microscope using x-z scans in reflection mode. The method for preparing cross-sections was adapted from one used with tissue culture cells on substrates, and which has also been employed with clay minerals. A BEEM capsule half filled with embedding resin was inverted over the glass substrate and TiO2 film, so that the resin was in contact with the film. After polymerisation at 60 deg C overnight, the block was pried away from the glass using a single edged razor blade, leaving the titania film in the resin. The final height of block was about 4-5 mm, and could be directly fitted into a5 mm, and could be directly fitted into an ultramicrotome chuck for sectioning without requiring re-embedding. Ultrathin 60-80 nm sections were cut with a diamond knife, collected on 200 mesh copper grids, then coated with carbon to stabilise the unsupported resin. The sections were examined at 200kV in a Philips CM200 TEM. It was found that the film had detached fully from the glass. The TiO2 grains were observed as mixtures of tetrahedral and rhombohedral geometries with a size distribution in the range 10-25 nm. Anatase and brookite phases present could be identified by electron diffraction. A Ru-containing dye was incorporated in some films, and energy-dispersive X-ray microanalysis was then used to assess the distribution of dye in the cross-sections. Cross-section preparation by the more conventional method of ion-beam thinning can produce thinner specimens and allows the interface between the film and substrate to be studied, but the procedure is more time-consuming. However ultramicrotomy can be a useful complementary technique for relatively rapid TEM examination of thin film cross-sections. Copyright (2002) Australian Society for Electron Microscopy Inc

112

A new room temperature gas sensor based on pigment-sensitized TiO2 thin film for amines determination.  

Science.gov (United States)

A new room temperature gas sensor was fabricated with pigment-sensitized TiO2 thin film as the sensing layer. Four natural pigments were extracted from spinach (Spinacia oleracea), red radish (Raphanus sativus L), winter jasmine (Jasminum nudiflorum), and black rice (Oryza sativa L. indica) by ethanol. Natural pigment-sensitized TiO2 sensor was prepared by immersing porous TiO2 films in an ethanol solution containing a natural pigment for 24h. The hybrid organic-inorganic formed films here were firstly exposed to atmospheres containing methylamine vapours with concentrations over the range 2-10ppm at room temperature. The films sensitized by the pigments from black-rice showed an excellent gas-sensitivity to methylamine among the four natural pigments sensitized films due to the anthocyanins. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of methylamine (r=0.931). At last, the black rice pigment sensitized TiO2 thin film was used to determine the biogenic amines generated by pork during storage. The developed films had good sensitivity to analogous gases such as putrscine, and cadaverine that will increase during storage. PMID:24934102

Yanxiao, Li; Xiao-Bo, Zou; Xiao-Wei, Huang; Ji-Yong, Shi; Jie-Wen, Zhao; Holmes, Mel; Hao, Limin

2014-06-01

113

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

114

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English 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 depo [...] sited 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.

2007-12-01

115

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

2007-12-01

116

Etch Characterization of TiO2 Thin Films Using Metal-Insulator-Metal Capacitor in Adaptively Coupled Plasma  

Science.gov (United States)

In this work, we investigated the etching characteristics of TiO2, and SiO2 thin films and the selectivity of TiO2 to SiO2 in a CF4/Ar adaptively coupled plasma (ACP) system. The maximum etch rates of TiO2, and for SiO2 thin films were 99 and 255.6 nm/min at a gas mixing ratio of CF4 (75%)/Ar (25%). At the same time, the etch rate was measured as a function of the etching parameters, such as the ACP source power, bias power and process pressure. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment, as well as the accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the CF4-containing plasmas.

Woo, Jong-Chang; Joo, Young-Hee; Kim, Chang-Il

2011-08-01

117

Layer-by-layer TiO(2)/WO(3) thin films as efficient photocatalytic self-cleaning surfaces.  

Science.gov (United States)

New TiO2/WO3 films were produced by the layer-by-layer (LbL) technique and successfully applied as self-cleaning photocatalytic surfaces. The films were deposited on fluorine doped tin oxide (FTO) glass substrates from the respective metal oxide nanoparticles obtained by the sol-gel method. Thirty alternative immersions in pH = 2 TiO2 and pH = 10 WO3 sols resulted in ca. 400 nm thick films that exhibited a W(VI)/Ti(IV) molar ratio of 0.5, as determined by X-ray photoelectron spectroscopy. Scanning electron microscopy, along with atomic force images, showed that the resulting layers are constituted by aggregates of very small nanoparticles (<20 nm) and exhibited nanoporous and homogeneous morphology. The electronic and optical properties of the films were investigated by UV-vis spectrophotometry and ultraviolet photoelectron spectroscopy. The films behave as nanoscale heterojunctions, and the presence of WO3 nanoparticles caused a decrease in the optical band gap of the bilayers compared to that of pure LbL TiO2 films. The TiO2/WO3 thin films exhibited high hydrophilicity, which is enhanced after exposition to UV light, and they can efficiently oxidize gaseous acetaldehyde under UV(A) irradiation. Photonic efficiencies of ? = 1.5% were determined for films constituted by 30 TiO2/WO3 bilayers in the presence of 1 ppm of acetaldehyde, which are ?2 times higher than those observed for pure LbL TiO2 films. Therefore, these films can act as efficient and cost-effective layers for self-cleaning, antifogging applications. PMID:25216058

Patrocinio, Antonio Otavio T; Paula, Leonardo F; Paniago, Roberto M; Freitag, Janna; Bahnemann, Detlef W

2014-10-01

118

Rutherford backscattering analysis of porous thin TiO 2 films  

Science.gov (United States)

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 TiO 2 mesoporous films measured by Rutherford backscattering (RBS),transmission electron microscopy (TEM), and atmospheric poroellipsometry.

Mayer, M.; von Toussaint, U.; Dewalque, J.; Dubreuil, O.; Henrist, C.; Cloots, R.; Mathis, F.

2012-02-01

119

Rutherford backscattering analysis of porous thin TiO2 films  

International Nuclear Information System (INIS)

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.

120

Photoactive and self-cleaning TiO2–SiO2 thin films on 316L stainless steel  

International Nuclear Information System (INIS)

In this study, TiO2–SiO2 nanocomposite films with different amounts of SiO2 were prepared by sol–gel process and were coated onto stainless steel 316L. The effect of addition of various amount of SiO2 in the precursor solution on the photocatalysis, photo-generated hydrophilicity and self-cleaning property of TiO2 thin films was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements and UV spectroscopy. In the tested ranges of SiO2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO2 sample sintered at 750 °C. Addition of less than 30 mol% SiO2 had a suppressive effect on the transformation of anatase to rutile and on the crystal growth of anatase in the sintering heat treatment. Phase separation occurred in the composite films for SiO2 content of 30 mol% or more. - Highlights: ? We study the effect of SiO2 addition on the photocatalysis of TiO2 films. ? By adding silica to TiO2, the photocatalysis activity of films can be improved. ? Addition of SiO2 can suppress the transformation of anatase to rutile. ? SiO2 addition prevents the growth of TiO2 grains during the sintering process.

121

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.

122

Surface chemistry and optical property of TiO2 thin films treated by low-pressure plasma  

International Nuclear Information System (INIS)

The low temperature RF plasma treatment was used to control the surface chemistry and optical property of TiO2 thin films deposited by RF magnetron sputtering with a very good uniformity at 300 deg. C substrate heating temperature. The XRD pattern indicates the crystalline structure of the film could be associated to amorphous structure of TiO2 in thin film. The plasma treatment of TiO2 film can increase the proportion of Ti3+ in Ti2p and decrease in carbon atoms as alcohol/ether group in C1s at the surface. The optical transmittance of the film was enhanced by 50% after the plasma treatment. The surface structure and morphology remain the same for untreated and low-pressure plasma-treated films. Therefore, increase in the optical transmission could be due to change in surface chemistry and surface cleaning by plasma treatment. - Graphical abstract: The surface chemistry and surface states of TiO2 films was modified using low-pressure RF plasma treatment. The surface roughness and crystalline structure remain unchanged for low-pressure plasma-treated films. There was an increase in the Ti3+ surface states of Ti2p at the surface and this can be useful to increase the photocatalytic activities of TiO2 films. The proportion of carbon atoms as carboxyl group in C1s was also increased after plasma treatment. All the plasma-treated films show a higher optical transmittance when untreated and it wasal transmittance when untreated and it was increased when the power was increased. The increase in the optical transmission could be due to surface cleaning of films by plasma treatment and possibly due to change in the surface chemistry

123

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

124

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

125

THIN SOLID FILMS OF OXIDES, TIO2, FE2O3, AND SnO2, PREPARED BY ORGANOMETALLIC  

OpenAIRE

Thin oxide films of TiO2, Fe2O3n, and SnO2, have been prepared by the organometallic chemical vapor deposition (MO-CVD) technique. The structure and character of these oxide films were determined by X-ray diffraction, electron microscopy, electron diffraction and UV absorption. These properties are reported. The photoelectrochemical behavior of these films on silicon single crystals as electrodes are also reported.

Luo, Wenxiu; Tan, Zhongke

1989-01-01

126

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 t 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.

127

Formation of TiO2 Thin Films using NH3 as Catalyst by Metalorganic Chemical Vapor Deposition  

Science.gov (United States)

We have studied metalorganic chemical vapor deposition of TiO2 thin films using titanium tetra-isopropoxide [TTIP, Ti(O--C3H7)4] and NH3 as a catalyst at deposition temperatures ranging from 250 to 365°C. At deposition temperatures above 330°C, pyrolytic self-decomposition of TTIP is dominant regardless of the use of NH3, and the activation energy for TiO2 film formation is 152 kJ/mol. At deposition temperatures below 330°C, the films can be formed with the help of the catalytic activity of NH3, and the activation energy is reduced to 55 kJ/mol. TiO2 films deposited through the pyrolytic self-decomposition of TTIP have an anatase structure before and after performing post-deposition annealing in oxygen ambient for 30 min at 750°C. On the other hand, the as-deposited films formed through the catalytic reaction of TTIP with NH3 incorporate nitrogen impurities and have microcrystallites of the rutile structure within the amorphous matrix. However, the post-deposition annealing, the nitrogen impurities are completely removed from the films, and the films are converted into polycrystalline TiO2 films with the rutile structure, which have a high dielectric constant of 82 and a low leakage current.

Jung, Sung-Hoon; Kang, Sang-Won

2001-05-01

128

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

129

Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.  

Science.gov (United States)

Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation. PMID:18449260

Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

2008-05-01

130

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

131

Preparation, stabilization and characterization of TiO2 on thin polyethylene films (LDPE): Photocatalytic applications  

OpenAIRE

An innovative way to fix preformed nanocrystalline TiO2 on low-density polyethylene film (LDPE-TiO2) is presented. The LDPE-TiO2 film was able to mediate the complete photodiscoloration of Orange II using about seven times less catalyst than a TiO2 suspension and proceeded with a photonic efficiency of ~0.02. The catalyst shows photostability over long operational periods during the photodiscoloration of the azo dye Orange II. The LDPE-TiO2 catalyst leads to full dye discoloration under simul...

Yu, Zy; Mielczarski, E.; Mielczarski, J.; Laub, D.; Buffat, Ph; Klehm, U.; Albers, P.; Lee, K.; Kulik, A.; Kiwi-minsker, L.; Renken, A.; Kiwi, J.

2007-01-01

132

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

International Nuclear Information System (INIS)

Highlights: ? Nanocrystalline rutile TiO2 thin film has been deposited by e-beam physical vapor deposition (EBPVD) method. ? A vacuum compatible target material (TiO2) was indigenously prepared for such deposition. ? A phase to phase (rutile to rutile) transformation was observed employing various characterization tools (XRD, RAMAN, UV–vis, FTIR and AFM). ? A process induced self annealing phenomenon shows a strong effect on the structural, morphological and optical properties of deposited thin films. ? The deposited film has sufficient possibility to realize a novel thin film material in the fabrication of active devices. - Abstract: In this work the preparation, deposition and structural properties of titanium oxide (TiO2) thin films were investigated. The films were deposited by means of the e-beam physical vapor deposition (EBPVD) method in high vacuum (10?7 Torr). A controlled deposition rate in the range of 0.1–0.3 ?/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (1 0 0) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV–visible Spectroscopy (UV–vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO2 layer betwe>2 layer between TiO2 and the substrate and the minor anatase crystalline phase of TiO2 was also identified in FTIR analysis. Grain size was found to be in the range of 100–125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO2 target to thin film.

133

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-04-01

134

Role of oxygen vacancies in anodic TiO2 thin films  

International Nuclear Information System (INIS)

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

135

Heteroepitaxial growth and structural characterization of rutile TiO2 thin films on GaN (0 0 0 1) templates prepared by pulsed laser deposition  

International Nuclear Information System (INIS)

Rutile TiO2 (1 0 0) thin films have been prepared on GaN (0 0 0 1) surfaces in the temperature range 300–600 °C by pulsed laser deposition (PLD) method. The effects of both the oxygen pressure and the substrate temperature on the properties of the TiO2 films were investigated. TiO2 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscope (TEM). Optimum parameters have been determined for growing high-quality TiO2 thin films with a sharp interface, in which the epitaxial orientation relationship between rutile TiO2 and GaN is TiO2 [001] //GaN [112¯0]. The surface morphology of TiO2 thin films exhibited a marked dependence on the substrate temperature, and the better crystallinity of the TiO2 thin films can be obtained at lower oxygen pressure

136

Chemical vapor deposition and characterization of nitrogen doped TiO2 thin films on glass substrates  

OpenAIRE

Photocatalytically active, N-doped TiO2 thin films were prepared by low pressure metalorganic chemical vapor deposition (MOCVD) using titanium tetra-iso-propoxide (TTIP) as a precursor and NH3 as a reactive doping gas. We present the influence of the growth parameters (temperature, reactive gas phase composition) on the microstructural and physico-chemical characteristics of the films, as deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrosco...

Sarantopoulos, Christos; Gleizes, Alain; Maury, Francis

2009-01-01

137

Broad band optical characterization of sol-gel TiO2 thin film microstructure evolution with temperature  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films have been produced by spin coating a titanium isopropoxide sol on silicon wafer substrates. The structural evolution of the thin films in terms of decomposition, crystallization and densification has been monitored as a function of annealing temperature from 100 to 700 oC using optical characterization and other techniques. The effect of annealing temperature on the refractive index and extinction coefficient of these TiO2 thin films was studied in the range of 0.62 to 4.96 eV photon energy (250-2000 nm wavelength) using spectroscopic ellipsometry. Thermal gravimetric analysis and atomic force microscopy support the ellipsometry data and provide information about structural transformations in the titania thin films with respect to different annealing temperatures. These data help construct a coherent picture of the decomposition of the sol-gel precursors and the creation of dense layers of TiO2. It was observed that the refractive index increased from 2.02 to 2.45 at 2.48 eV (500 nm) in sol-gel spin coated titania films for annealing temperatures from 100 oC to 700 oC.

138

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

International Nuclear Information System (INIS)

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

139

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. PMID:22747886

Ghrairi, Najla; Bouaicha, Mongi

2012-01-01

140

Three-Dimensional Finite Element Analysis of Phase Change Memory Cell with Thin TiO2 Film  

International Nuclear Information System (INIS)

A thin TiO2 layer inserted in a phase change memory (PCM) cell to form a deep sub-micro bottom electrode (DBE) is proposed and its electro-thermal characteristics are investigated with the three-dimensional finite element analysis. Compared with the conventional PCM cell with a SiN stop layer, the reset threshold current of the PCM cell with the TiO2 layer is reduced from 1.8 mA to 1.2 mA and the ratio of the amorphous resistance and crystalline resistive increases from 65 to 100. The optimum thickness of the TiO2 layer and the optimum height of DBE are 10 nm and 200 nm, respectively. Therefore, the PCM cell with the TiO2 layer can decrease the programming power consumption and increase heating efficiency. The TiO2 film is a better candidate for the SiN film in the PCM cell structure to prepare DBE and to reduce programming power in the reset operation. (cross-disciplinary physics and related areas of science and technology)

141

Surface preparation influence on the initial stages of MOCVD growth of TiO2 thin films  

International Nuclear Information System (INIS)

In situ chemical surface analyses using X-ray photoelectron spectroscopy (XPS), completed by ex situ atomic force microscopy (AFM) analyses, were performed in order to compare the initial stages of MOCVD growth of TiO2 thin films on two different surface types. The first type was a silicon native oxide free hydrogen terminated surface and the second one was a silicon dioxide surface corresponding to a thin layer of 3.5 nm thick in situ thermally grown on silicon substrate. Si(100) was used as substrate, and the growths of TiO2 thin films were achieved with titanium tetraisopropoxide (TTIP) as precursor under a temperature of 675 deg. C, a pressure of 0.3 Pa and a deposition time of 1 h. Whatever the surface is, the deposited titanium amount was globally the same in the two cases. On the contrary, the deposit morphology was different: a covering layer composed of a SiO2 and TiO2 phases mixture on the hydrogen terminated surface, and small TiO2 clusters homogeneously spread on the SiO2 surface

142

CVD elaboration of nanostructured TiO2-Ag thin films with efficient antibacterial properties  

OpenAIRE

Nanostructured TiO2-Ag composite coatings are deposited by direct liquid injection metal-organic (DLI-MO) CVD at 683K in a one-step process. Silver pivalate (AgPiv) and titanium tetra-iso-propoxide (TTIP) are used as Ag and Ti molecular precursors, respectively. Metallic silver nanoparticles are co-deposited with anatase TiO2 on stainless steel, glass, and silicon wafers. The silver particles are uniformly embedded in the oxide matrix through the entire film thickness. The influence of the gr...

Mungkalasiri, Jitti; Bedel, Laurent; Emieux, Fabrice; Dore, Jeanne; Renaud, Franc?ois N. R.; Sarantopoulos, Christos; Maury, Francis

2010-01-01

143

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

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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

2013-04-01

144

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

International Nuclear Information System (INIS)

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 450oC 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.

145

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

146

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

147

A simple and low temperature process for super-hydrophilic rutile TiO2 thin films growth  

International Nuclear Information System (INIS)

We investigate an environmentally friendly aqueous solution system for rutile TiO2 violet color nanocrystalline thin films growth on ITO substrate at room temperature. Film shows considerable absorption in visible region with excitonic maxima at 434 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, water surface contact angle and energy dispersive X-ray analysis (EDX) techniques in addition to actual photo-image that shows purely rutile phase of TiO2 with violet color, super-hydrophilic and densely packed nanometer-sized spherical grains of approximate diameter 3.15 ± 0.4 nm, characterize the films. Band gap energy of 4.61 eV for direct transition was obtained for the rutile TiO2 films. Film surface shows super-hydrophilic behavior, as exhibited water contact angle was 7o. Strong visible absorption (not due to chlorine) leaves future challenge to use these films in extremely thin absorber (ETA) solar cells

148

Effect of the top electrode materials on the resistive switching characteristics of TiO2 thin film  

International Nuclear Information System (INIS)

Various metals, such as Pt, stainless steel (SUS), Al, Ni, and Ti, were used as a top electrode (TE) to evaluate the dependency of the resistive switching characteristics on the TE of the metal/TiO2/Pt structure. The variation of the chemical composition of TiO2 in the metal/TiO2/Pt structure before and after switching was examined to identify the factors affecting the resistive switching characteristics of the samples with various TE materials. In the case of TE/TiO2/Pt structures showing unstable resistive switching behavior, e.g., those with the Al, Ni, and Ti TEs, secondary ion mass spectrometry revealed an increase in the oxygen concentration at the interface area between the TE metal and TiO2. This suggests that the oxidation reaction at the interface between the TE metal and TiO2 might cause the TE/TiO2/Pt structure to exhibit unstable resistive switching characteristics. According to these results, the oxidation reaction at the interface between the metal TE and TiO2 thin film is a primary factor affecting the resistive switching characteristics of TiO2-based Resistive Random Access Memory devices.

149

Glancing angle synthesized indium nanoparticles covered TiO2 thin film and its structural, optoelectronic properties  

Science.gov (United States)

Surface plasmon resonance is one of the most interesting phenomena shown by noble metal nanoparticles (NPs) in nanoscale dimension. Gold, silver NPs used to show enhancement in absorption at their selective plasmon resonance frequency. But indium (In) shows broader resonance, and hence, In NPs can be employed for the purpose of wideband detection. Here, glancing angle deposition is incorporated in an e-beam chamber to obtain controlled growth of 5, 10 and 30 nm In NPs array over TiO2 thin film (TF) on ITO-coated glass plate. The 5-nm In NPs on TiO2 TF process superior performances in terms of enhanced Raman scattering and optical absorption. Optical absorption spectrophotometry shows averagely two times enhancement in absorption for 5-nm In NPs compared to bared TiO2 TF on Si substrate. The plasmonic detector (TiO2 TF/5-nm In NPs/TiO2 TF/Si) produced dark current of 0.36 µA/cm2 at 5 V, which increased to 0.51 µA/cm2 under white light illumination. The maximum 116 times photosensitivity at -2 V was calculated for the plasmonic device. The NPs-designed plasmonic device shows twofold photoresponsivity in visible region (400-650 nm) with respect to the bared TiO2TF device. The external quantum efficiency for plasmonic device was calculated to be 65 %.

Choudhuri, B.; Mondal, A.; Ganguly, A.; Saha, A. K.; Chattopadhyay, K. K.

2015-01-01

150

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

International Nuclear Information System (INIS)

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

151

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

Science.gov (United States)

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

Liu, Qinghua; Jiang, Yong; Yan, Wensheng; Sun, Zhihu; Pan, Zhiyun; Yao, Tao; Wu, Ziyu; Wei, Shiqiang

2009-11-01

152

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

International Nuclear Information System (INIS)

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

153

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

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

Eshaghi A.

2013-09-01

154

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.

155

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

Science.gov (United States)

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

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

2014-06-20

156

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 activitymproved photocatalytical activity

157

Adsorption and solar light decomposition of acetone on anatase TiO2 and niobium doped TiO2 thin films.  

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Adsorption and solar light decomposition of acetone was studied on nanostructured anatase TiO2 and Nb-doped TiO2 films made by sol-gel methods (10 and 20 mol % NbO2.5). A detailed characterization of the film materials show that films contain only nanoparticles with the anatase modification with pentavalent Nb oxide dissolved into the anatase structure, which is interpreted as formation of substituted Nb=O clusters in the anatase lattice. The Nb-doped films displayed a slight yellow color and an enhanced the visible light absorption with a red-shift of the optical absorption edge from 394 nm for the pure TiO2 film to 411 nm for 20 mol % NbO2.5. In-situ Fourier transform infrared (FTIR) transmission spectroscopy shows that acetone adsorbs associatively with eta1-coordination to the surface cations on all films. On Nb-doped TiO2 films, the carbonyl bonding to the surface is stabilized, which is evidenced by a lowering of the nu(C=O) frequency by about 20 cm(-1) to 1672 cm(-1). Upon solar light illumination acetone is readily decomposed on TiO2, and stable surface coordinated intermediates are formed. The decomposition rate is an order of magnitude smaller on the Nb-doped films despite an enhanced visible light absorption in these materials. The quantum yield is determined to be 0.053, 0.004 and 0.002 for the pure, 10% Nb:TiO2, and 20%Nb:TiO2, respectively. Using an interplay between FTIR and DFT calculations we show that the key surface intermediates are bidentate bridged formate and carbonate, and H-bonded bicarbonate, respectively, whose concentration on the surface can be correlated with their heats of formation and bond strength to coordinatively unsaturated surface Ti and Nb atoms at the surface. The oxidation rate of these intermediates is substantially slower than the initial acetone decomposition rate, and limits the total oxidation rate at t>7 min on TiO2, while no decrease of the rate is observed on the Nb-doped films. The rate of degradation of key surface intermediates is different on pure TiO2 and Nb-doped TiO2, but cannot explain the overall lower total oxidation rate for the Nb-doped films. Instead the inferior photocatalytic activity in Nb-doped TiO2 is attributed to an enhanced electron-hole pair recombination rate due to Nb=O cluster and cation vacancy formation. PMID:16471666

Mattsson, Andreas; Leideborg, Michael; Larsson, Karin; Westin, Gunnar; Osterlund, Lars

2006-01-26

158

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.

159

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

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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.

Adami, A.; Decarli, M.; Bartali, R.; Micheli, V.; Laidani, N.; Lorenzelli, L.

2010-01-01

160

Optical and photocatalytic properties of TiO2/Ag–SiO2 nanocomposite thin films  

International Nuclear Information System (INIS)

Highlights: ? The TiO2/Ag–SiO2 nanocomposite films were prepared by sol–gel spin-coating method. ? The optimal Ag loading for the highest photocatalytic efficiency is 15 at.%. ? The enhanced photocatalytic efficiency is attributed to the LSP of Ag NPs. - Abstract: The TiO2/Agx–(SiO2)1?x nanocomposite thin films with a bilayer structure were prepared via a chemical solution approach combined with a sol–gel spin-coating processing. The TiO2/Ag0.15–(SiO2)0.85 thin film is about 200 nm in thickness including a top anatase–TiO2 layer approximately 60 nm, while the approximately spherical Ag nanoparticles with 10–30 nm in diameter were embedded uniformly in the amorphous SiO2 matrix of the sublayer. The UV–Vis absorption peaks appeared in the wavelength of 420 nm due to the surface plasmon resonance (SPR) of Ag particles. The SPR peaks manifest a red-shift with increasing Ag content from 6 to 15 at.%, whereas blue-shift from 15 to 20 at.%. The photocatalytic activity enhanced by increasing Ag content up to 15 at.% but reduced by further increasing Ag content. It is found that the optimal Ag loading for achieving the highest photocatalytic activity is 15 at.%.

161

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

OpenAIRE

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

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

2013-01-01

162

Study on TiO2 thin films grown by advanced pulsed laser deposition on ITO  

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TiO2 films were grown by an advanced pulsed laser deposition method (PLD) on ITO substrates to be used as functional electrodes in the manufacturing of solar cells. A pure titanium target (99.99%) was irradiated by a Nd:YAG laser (355 and 532 nm, 5 ns, 35 mJ, 3 J/cm2) in an oxygen atmosphere at different pressures (20-160 mTorr) and at room temperature. After deposition, the films were subjected to an annealing process at 350 oC. The film structure, surface morphology, thickness, roughness, and optical transmission were investigated. Regardless of the wavelength used, the films deposited at room temperature presented only Ti2O and TiO peaks. After thermal treatment, the TiO2 films became strongly crystalline, with a tetragonal structure and in the anatase phase; the threshold temperature value was 250 oC. The deposition rate was in the range of 0.035-0.250 nm/pulse, and the roughness was 135-305 nm. Optical transmission of the films in the visible range was between 40% and 60%.

163

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

International Nuclear Information System (INIS)

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

164

Chemical vapor deposition and characterization of nitrogen doped TiO2 thin films on glass substrates  

International Nuclear Information System (INIS)

Photocatalytically active, N-doped TiO2 thin films were prepared by low pressure metalorganic chemical vapor deposition (MOCVD) using titanium tetra-iso-propoxide (TTIP) as a precursor and NH3 as a reactive doping gas. We present the influence of the growth parameters (temperature, reactive gas phase composition) on the microstructural and physico-chemical characteristics of the films, as deduced from X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and ultra-violet and visible (UV/Vis) spectroscopy analysis. The N-doping level was controlled by the partial pressure ratio R = [NH3]/[TTIP] at the entrance of the reactor and by the substrate temperature. For R = 2200, the N-doped TiO2 layers are transparent and exhibit significant visible light photocatalytic activity (PA) in a narrow growth temperature range (375-400 oC). The optimum N-doping level is approximately 0.8 at.%. However, the PA activity of these N-doped films, under UV light radiation, is lower than that of undoped TiO2 films of comparable thickness.

165

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

166

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

167

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

International Nuclear Information System (INIS)

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

168

Growth of TiO2 thin films by AP-MOCVD on stainless steel substrates for photocatalytic applications  

OpenAIRE

TiO2 thin films were deposited under atmospheric pressure by MOCVD in the temperature range 400-600 °C on stainless steel and Si(100) substrates. Titanium tetraisopropoxide (TTIP) was used as Ti and O source. Single-phased anatase and bi-phased (anatase/rutile) coatings with controlled composition have been deposited depending on the temperature and the TTIP mole fraction. The films grown on stainless steel at low temperature (b420 °C) and low TTIP mole fraction (b10?4) are constituted of...

Duminica, Florin-daniel; Maury, Francis; Hausbrand, R.

2007-01-01

169

Effect of electrode type in the resistive switching behaviour of TiO2 thin films  

International Nuclear Information System (INIS)

The influence of the electrode/active layer on the electric-field-induced resistance-switching phenomena of TiO2-based metal-oxide-metal devices (MOM) is studied. TiO2 active layers were fabricated by the reactive rf-sputtering technique and devices were made by sandwiching between several metal electrodes. Three different MOM devices were made, according with the junction type formed between the electrode and the TiO2 active layer, those where Ohmic-Ohmic, Ohmic-Schottky and Schottky-Schottky. The junction type was tested by electrical I-V measurements. It was found that MOM devices made with the Ohmic-Ohmic combination did not show any resistive switching behaviour in contrast with devices made with Ohmic-Schottky and Schottky-Schottky combinations. From a detailed analysis of the I-V curves it was found that transport characteristics are Ohmic for the low-resistance state for all the contacts combinations of the MOM devices, whereas in the high-resistance state it depends on contact combinations and can be identified as Ohmic, Schottky and Poole-Frenkel type. These conduction mechanisms in the low- and high-resistance states suggest that formation and rupture of conducting filaments through the film oxide is the mechanism responsible for the resistance switching.

170

Photocatalytic properties of dense plasma focus deposited nano phase TiO2 thin films: annealing effect  

International Nuclear Information System (INIS)

Successful deposition of nano phase TiO2 thin films on silicon and glass substrates were achieved using the dense plasma focus (DPF) device. TiO2 thin films were prepared from a 99.95% pure titanium rod in oxygen–argon working gas mixture at ambient room temperature. The EDX and XPS results give the elemental composition of the films as Ti and O2. The XRD shows that amorphous films are predominant for low number of plasma focus shots. The SEM micrographs confirm the presence of nano-sized grains at smaller number of deposition shots or higher distance of deposition. Agglomeration was found to increase with the number of deposition shots. On annealing, the XRD diffractograms exhibit an increased in intensity and line width of the anatase (101) with the rutile phase R (110) emerging above 400°C. UV-Vis absorbance spectra for both as deposited and annealed films show a red shift for depositions from 20 plasma focus shots. The films showed visible light catalytic activity through decolouration of methylene blue solution. Visible light activity reached a maximum and decreased after 600 °C. Red shift and visible light catalysis can be explained in terms of the special feature effects of the plasma focus characteristic emissions. (author)

171

Effect of calcinations temperature on microstructures, photocatalytic activity and self-cleaning property of TiO2 and SnO2/TiO2 thin films prepared by sol-gel dip coating process  

Science.gov (United States)

The purpose of this research was to study the effect of calcinations temperature on phase transformation, crystallite size, morphology, photocatalytic activity and self-cleaning properties of TiO2 and SnO2/TiO2 thin films. The thin films were preparation by sol-gel dip coating process and calcinations at the temperature of 500 °C, 600 °C and 700 °C for 2 h with the heating rate of 10 °C/mim. The microstructures of the fabricated thin films were characterized by XRD and SEM techniques. The photocatalytic activity of the thin films was also tested via the degradation of methylene blue solution under UV irradiation. Finally, self-cleaning properties of thin films were evaluated by measuring the contact angle of water droplet on the thin films with and without UV irradiation. It was found that SnO2/TiO2 thin films calcinations at the temperature of 500 °C shows the highest of photocatalytic activity and self-cleaning properties.

Sangchay, Weerachai

2014-06-01

172

DLI-CVD of TiO2–Cu antibacterial thin films: Growth and characterization  

OpenAIRE

TiO2–Cu nanocomposite films were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on stainless steel, silicon and glass substrates with the goal to produce bactericidal surfaces. Copper bis (2,2,6,6-tetramethyl-3,5-heptadionate), Cu(TMHD)2, and titanium tetra-iso-propoxide, TTIP, were used as metalorganic precursors. Liquid solutions of these compounds in xylene were injected in a flash vaporization chamber connected to a cold wall MOCVD reactor. The deposition tem...

Mungkalasiri, Jitti; Bedel, Laurent; Emieux, Fabrice; Dore, Jeanne; Renaud, Franc?ois N. R.; Maury, Francis

2009-01-01

173

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

2010-01-01

174

Spray pyrolysed microporous TiO2 thin films by optimisation of substrate temperature for ‘all sprayed’ solar cells  

Science.gov (United States)

Titanium dioxide thin films were deposited on glass substrate at temperatures ranging from 300 °C to 500 °C by a simple, cost effective spray pyrolysis method using commercially available TiO2 powder (Degussa P25). Analyses using scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal the microporous nature of the films at 350 °C. X-ray diffraction (XRD) and Raman studies reveal that these films are amorphous in nature. The films were subsequently annealed at 500 °C for 2 h, resulting in crystallisation (the tetragonal anatase phase). XPS analysis was effectively used to study the chemical composition of the samples. Finally, optimized microporous TiO2 thin films were used for the fabrication of an ‘all-sprayed’ solar cell utilizing well-established CuInS2 as the absorber layer. The best device under this study has an open-circuit voltage of 409 mV and a short-circuit current density of 3.90 mA cm?2. The efficiency and fill factor were 0.61% and 38%, respectively.

Santhosh, M. V.; Deepu, D. R.; Geethu, R.; Rajeev Kumar, K.; Sudha Kartha, C.; Vijayakumar, K. P.

2014-11-01

175

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

International Nuclear Information System (INIS)

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.

176

Oxidative degradation of industrial wastewater using spray deposited TiO2/Au:Fe2O3 bilayered thin films.  

Science.gov (United States)

The Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400°C and 470°C, respectively onto amorphous and F:SnO2 coated glass substrates. The effect of TiO2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe2O3, Au:Fe2O3, TiO2/Fe2O3 and TiO2/Au:Fe2O3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc=185?A and Voc=450mV) are at 38nm thickness of TiO2. Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64cm(2)) TiO2/Au:Fe2O3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO2/Au:Fe2O3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95mg/L to 13mg/L and 75mg/L to 11mg/L, respectively was also observed. PMID:25463684

Mahadik, M A; Shinde, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

2014-11-01

177

TiO2 anatase thin films deposited by spray pyrolysis of an aerosol of titanium diisopropoxide  

International Nuclear Information System (INIS)

Titanium dioxide thin films were deposited on crystalline silicon (100) and fused quartz substrates by spray pyrolysis (SP) of an aerosol, generated ultrasonically, of titanium diisopropoxide. The evolution of the crystallization, studied by X-ray diffraction (XRD), atomic force (AFM) and scanning electron microscopy (SEM), reflection and transmission spectroscopies, shows that the deposition process is nearly close to the classical chemical vapor deposition (CVD) technique, producing films with smooth surface and good crystalline properties. At deposition temperatures below 400 deg. C, the films grow in amorphous phase with a flat surface (roughness?0.5 nm); while for equal or higher values to this temperature, the films develop a crystalline phase corresponding to the TiO2 anatase phase and the surface roughness is increased. After annealing at 750 deg. C, the samples deposited on Si show a transition to the rutile phase oriented in (111) direction, while for those films deposited on fused quartz no phase transition is observed

178

Highly efficient photoelectrochemical performance of SrTiO3/TiO2 heterojunction nanotube array thin film  

International Nuclear Information System (INIS)

SrTiO3–TiO2 heterojunction thin-film nanotube arrays (SNTs, the average inner diameter is about 50 nm) was fabricated via electrochemical anodization followed by a hydrothermal treatment. The photo-to-current conversion properties and the photoelectrochemical performance for cathodic protection of carbon steel in 0.5 M of sodium chloride solution under white light illumination were investigated. The results showed that the highly ordered nanotube arrays could provide very excellent cathodic protection for carbon steel under white light irradiation.

179

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.

180

Berreman effect applied to phase characterization of thin films supported on metallic substrates: The case of TiO2  

Science.gov (United States)

Infrared reflection-absorption spectra of TiO2 thin films deposited by plasma-enhanced chemical vapor deposition onto aluminum and by a sol-gel process onto platinum were obtained using s- and p-polarized light and oblique incidence angles. Prominent bands with variable reflection minima position and line shapes, which were shown to be phase dependent, were observed for all samples in the 800-900 cm-1 wave number range when p-polarized light and oblique incidence were used. Such bands were attributed to an LO mode of TiO2 and their enhancement with the incidence angle is a good example of Berreman effect. Such spectra were analyzed by means of spectral simulation based on the Fresnel equation for a three-layered system. The films' optical constants used in the simulations were obtained through the Kramers-Krönig analysis (KKA) of the reflectance spectra of pellets of powdered amorphous TiO2, anatase and rutile. Optical constants for hypothetical polycrystalline TiO2 systems were also calculated from the dielectric functions of single crystals by means of effective medium theories (EMTs), such as those of Bruggeman, Maxwell-Garnett, and Hunderi. These optical constants were used both for spectral simulation and for understanding the bands observed. However, the optical constants for the powdered standards determined through KKA reproduced experimental results more accurately than those determined through the EMTs. In both experimental and simulated spectra, Berreman effect was very clear-cut and a reliable phase characterization could be carried out.

Trasferetti, B. C.; Davanzo, C. U.; Zoppi, R. A.; da Cruz, N. C.; de Moraes, M. A. B.

2001-09-01

181

Origin of ferromagnetism in aluminum-doped TiO2 thin films: Theory and experiments  

Science.gov (United States)

In this paper, we combine first-principles calculations and experiments to investigate the magnetic properties of aluminum-doped TiO2 films of rutile structure. Density-functional theory with generalized gradient approximation based calculations were carried out for three cases, where the TiO2 lattice contains oxygen vacancies VO only, an oxygen is substituted by a fluorine atom, or a Ti is substituted by an aluminum. Magnetic moments associated with the formation of Ti3+ ions are found in all cases but they couple differently resulting in different magnetic states. Al-doped samples prepared in our labs exhibit ferromagnetism at room temperature with a TC near 340 K. The experimental results are consistent with the first principles calculations, and the magnetism is associated with the VO defect electrons induced by the Al doping. The defect electron occupies nearby Ti sites giving rise to the Ti3+ moments and, at the same time, has spatially extended wavefunctions assuring overlapping between neighbors.

Wang, Xianjie; Song, Yongli; Tao, L. L.; Feng, J. F.; Sui, Yu; Tang, Jinke; Song, Bo; Wang, Yi; Wang, Yang; Zhang, Yu; Han, X. F.

2014-12-01

182

Synergistic effect on the photocatalytic degradation of 2-chlorophenol using TiO2 thin films doped with some transition metals in water  

International Nuclear Information System (INIS)

The metalorganic chemical vapor deposition (MOCVD) method has been used to prepare TiO2 thin films for the degradation of hazardous organic compounds, such as 2-chlorophenol (2-CP). The effect of supporting materials and metal doping on the photocatalytic activity of TiO2 thin films also has been studied. TiO2 thin films were coated onto various supporting materials, including stainless steel cloth(SS), quartz glass tube(QGT), and silica gel (SG). Transition metals,such as Pd(II), Pt(IV), Nd(III) and Fe(III), were doped onto TiO2 thin film. The results indicate that Nd(III) doping improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 ?m) appears to be the best support. An optimal amount of doping material at 1.0 percent (w/w) of TiO2-substrate thin film gives the best photodegradation 2-CP

183

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

International Nuclear Information System (INIS)

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 deg. 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.

184

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

International Nuclear Information System (INIS)

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

185

Al2O3/TiO2 nanolaminate thin film encapsulation for organic thin film transistors via plasma-enhanced atomic layer deposition.  

Science.gov (United States)

Organic electronic devices require a passivation layer that protects the active layers from moisture and oxygen because most organic materials are very sensitive to such gases. Passivation films for the encapsulation of organic electronic devices need excellent stability and mechanical properties. Although Al2O3 films obtained with plasma enhanced atomic layer deposition (PEALD) have been tested as passivation layers because of their excellent gas barrier properties, amorphous Al2O3 films are significantly corroded by water. In this study, we examined the deformation of PEALD Al2O3 films when immersed in water and attempted to fabricate a corrosion-resistant passivation film by using a PEALD-based Al2O3/TiO2 nanolamination (NL) technique. Our Al2O3/TiO2 NL films were found to exhibit excellent water anticorrosion and low gas permeation and require only low-temperature processing (<100 °C). Organic thin film transistors with excellent air-stability (52 days under high humidity (a relative humidity of 90% and a temperature of 38 °C)) were fabricated. PMID:24712401

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

2014-05-14

186

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

International Nuclear Information System (INIS)

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

187

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

188

Crystallite structure, surface morphology and optical properties of In2O3-TiO2 composite thin films by sol-gel method  

International Nuclear Information System (INIS)

The transparent In2O3-TiO2 composite thin films in nanoscales were prepared via sol-gel method on the float glass substrates, and characterized by X-ray diffraction (XRD), Raman scattering microscopy, atomic force microscopy (AFM), UV-vis spectrophotometer, and Hall-effect testing. It was found that the addition of In2O3 to TiO2 thin films could suppress the grain growth of TiO2 crystals and increase the surface smooth degree, the conductivity, carriers' concentration and mobility of the as-prepared TiO2 films. The band gap energy of the as-prepared In2O3-TiO2 composite thin films increases from 3.36 eV to 3.44 eV with the increment of In-ingredient in the precursor sols, which provides the potential application of the as-prepared composite thin film using as the anode of the dye-sensitized solar cells to improve the open-circuit voltage

189

Control of crystallographic texture and surface morphology of Pt/Tio2 templates for enhanced PZT thin film texture.  

Science.gov (United States)

Optimized processing conditions for Pt/TiO2/SiO2/Si templating electrodes were investigated. These electrodes are used to obtain [111] textured thin film lead zirconate titanate (Pb[ZrxTi1-x ]O3 0 ? x ? 1) (PZT). Titanium deposited by dc magnetron sputtering yields [0001] texture on a thermally oxidized Si wafer. It was found that by optimizing deposition time, pressure, power, and the chamber pre-conditioning, the Ti texture could be maximized while maintaining low surface roughness. When oxidized, titanium yields [100]-oriented rutile. This seed layer has as low as a 4.6% lattice mismatch with [111] Pt; thus, it is possible to achieve strongly oriented [111] Pt. The quality of the orientation and surface roughness of the TiO2 and the Ti directly affect the achievable Pt texture and surface morphology. A transition between optimal crystallographic texture and the smoothest templating surface occurs at approximately 30 nm of original Ti thickness (45 nm TiO2). This corresponds to 0.5 nm (2 nm for TiO2) rms roughness as determined by atomic force microscopy and a full-width at half-maximum (FWHM) of the rocking curve 0002 (200) peak of 5.5/spl degrees/ (3.1/spl degrees/ for TiO2). A Pb[Zr0.52Ti 0.48]O3 layer was deposited and shown to template from the textured Pt electrode, with a maximum [111] Lotgering factor of 87% and a minimum 111 FWHM of 2.4/spl degrees/ at approximately 30 nm of original Ti. PMID:25585390

Fox, Austin J; Drawl, Bill; Fox, Glen R; Gibbons, Brady J; Trolier-McKinstry, Susan

2015-01-01

190

Structural and electrical characteristics of ZrO2-TiO2 thin films by sol-gel method  

International Nuclear Information System (INIS)

In this paper, we investigated electrical properties and microstructures of ZrTiO4 (ZrO2-TiO2) thin films prepared by the sol-gel method on ITO substrates at different annealing temperatures. All films exhibited ZrTiO4 (1 1 1) and (1 0 1) orientations perpendicular to the substrate surface, and the grain size increased with increase in the annealing temperature. A low leakage current density of 2.06 x 10-6 A/cm2 was obtained for the prepared films. Considering the primary memory switching behavior of ZrTiO4, ReRAM based on ZrTiO4 shows promise for future nonvolatile memory applications.

191

Photocatalytic degradation of gaseous acetone, toluene, and p-xylene using a TiO2 thin film.  

Science.gov (United States)

A nano-structured TiO(2) thin film immobilized on glass springs was prepared by the sol-gel method, and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Acetone, toluene and p-xylene were chosen as common VOCs for a photocatalytic degradation study of both mixed and pure gases using the TiO(2) thin film. Addition of hydrogen peroxide promoted activation of the catalyst during acetone degradation. The effects of gas flow rate and UV light wavelength were investigated with the pure gases. Gas flow rate greatly influenced the degradation. The highest degradation rates were 77.7% (at 3 L/min) for acetone, 61.9% (at 3 L/min) for toluene, and 55% (at 7 L/min) for p-xylene. A UV light wavelength of 254 nm provided greater degradation of the VOCs than 365 nm UV light. The degradation rates of p-xylene and acetone in the gas mixture were lower than those of pure p-xylene and acetone. The opposite trend was observed for toluene. Acetone, both in the mixed gas and pure, had the highest degradation efficiency. Acetone, toluene and p-xylene degradation followed Langmuir-Hinshelwood kinetics. PMID:20665322

Liang, Wen J; Li, Jian; Jin, Yu Q

2010-09-01

192

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

CERN Document Server

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

193

Switching properties of vanadium doped TiO2 thin films prepared by magnetron sputtering  

International Nuclear Information System (INIS)

In the present work thin films of Ti-Me (where Me: V, Nb, Ta) were deposited onto glass substrates by magnetron sputtering of mosaic target in reactive oxygen plasma. The properties of the prepared thin films were studied by X-ray diffraction (XRD), electron dispersive spectroscopy, temperature-dependent electrical and optical transmission spectroscopy measurements. The structural investigations indicate that thin films were XRD-amorphous. Reversible thermoresistance effect, recorded at 52 ± 1 oC was found from electrical measurements. The prepared coatings were well transparent in the visible part of the light spectrum from ca. 350 nm.

194

Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels  

Energy Technology Data Exchange (ETDEWEB)

The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

Klobukowski, Erik R [ORNL; Tenhaeff, Wyatt E [ORNL; McCamy, James [PPG; Harris, Caroline [PPG; Narula, Chaitanya Kumar [ORNL

2013-01-01

195

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

196

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 demonstraomposition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.

197

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

2012-02-01

198

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

OpenAIRE

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 de...

Lek. Sikong; Kalayanee Kooptarnond; Sutham Niyomwas

2010-01-01

199

Improved room temperature electron mobility in self-buffered anatase TiO2 epitaxial thin film grown at low temperature  

Science.gov (United States)

Anatase TiO2(001) epitaxial thin films were grown on LaAlO3(001) substrate self-buffered with 5-monolayer-thick insulating TiO2 by pulsed laser deposition. The use of self-buffer layer enabled the layer-by-layer growth down to 200 °C resulting in the decreased surface roughness. The carrier density of self-buffered films was controlled as a function of oxygen pressure during the growth within a range of 1019 cm-3. The electron mobility at 300 K of self-buffered film grown at the optimal condition was improved to be 18.6 cm2·V-1·s-1 in comparison with that of non-buffered TiO2 thin film <5 cm2·V-1·s-1.

Krasienapibal, Thantip S.; Fukumura, Tomoteru; Hirose, Yasushi; Hasegawa, Tetsuya

2014-09-01

200

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

International Nuclear Information System (INIS)

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

201

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

International Nuclear Information System (INIS)

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

202

Physical properties of Zn doped TiO2 thin films with spray pyrolysis technique and its effects in antibacterial activity.  

Science.gov (United States)

Zinc doped Titanium dioxide (TiO2: Zn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 450°C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (101) plane at 8at.% of Zn-doped TiO2 film. Scanning electron microscopy (SEM) study showed the uniform distribution of grains with porous nature. Atomic force microscopy (AFM) observations indicated the tetragonal shape at 8at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398nm was observed at the 8at.% of Zn-doped TiO2 thin film. The carrier concentration and Hall mobility was increased with doping. The antibacterial activity was highly yielded for the Zn-doped TiO2 thin films. PMID:25479105

Arunachalam, A; Dhanapandian, S; Manoharan, C; Sivakumar, G

2015-03-01

203

Synthesis and characterization of photochromic Ag-embedded TiO2 nanocomposite thin films by non-reactive RF-magnetron sputter deposition  

International Nuclear Information System (INIS)

Ag-embedded TiO2 nanocomposite thin film with reversible photochromic properties were prepared by layer-by-layer non-reactive RF-magnetron sputtering. Films were produced in Ar/O2 and pure Ar atmospheres. In the oxidizing regime, a diffusion of Ag from the film volume to the outer film surface was observed. Therefore, pure Ar plasma was applied in the deposition of TiO2. The electronic and optical properties of the TiO2 film were almost not affected by the presence of oxygen. Transmission electron microscopy (TEM) and reflection mode X-ray absorption spectroscopy (XAS) were performed to study the morphology, crystal structure and chemical state of the embedded Ag nanoparticles before and after the annealing step. Annealing of the film led to the crystallization of the TiO2 matrix. Moreover, the Ag nanoparticles in the film underwent Ostwald ripening leading to particle agglomerate. No oxidation of the embedded Ag during the sputter deposition and subsequent annealing process was found as confirmed by XAS measurements. The non-reactive RF-magnetron method is believed to avoid the energetic oxygen ions attack to Ag during the deposition of Ag-embedded TiO2 nanocomposite and thus the films are expected to have better optical properties and long-term stability.

204

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

Science.gov (United States)

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

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

2014-06-01

205

Determination and analysis of dispersive optical constant of TiO2 and Ti2O3 thin films  

International Nuclear Information System (INIS)

Electron beam evaporation technique was used to prepare TiO2 and Ti2O3 thin films onto glass substrates of thicknesses 50, 500 and 1000nm for each sample. The structural investigations revealed that the as-deposited films are amorphous in nature. Transmittance measurements in the wavelength range (350-2000nm) were used to calculate the refractive index n and the absorption index k using Swanepoel's method. The optical constants such as optical band gap Egopt, optical conductivity ?opt, complex dielectric constant, relaxation time ? and dissipation factor tan? were determined. The analysis of the optical absorption data revealed that the optical band gap Eg was indirect transitions. The optical dispersion parameters Eo and Ed were determined according to Wemple and Didomenico method

206

Influência do tipo de ácido e tempo de envelhecimento na atividade fotocatalítica de filmes finos de TiO2 / Type of acid and ageing effect influence on photocatalytic activity of TiO2 thin films  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english TiO2 thin films were prepared by the sol-gel method using different acids (HCl and HAc), with a parallel evaluation of the gel ageing effects on the film properties. After the thermal treatments, the resulting materials were characterized through gravimetric analysis, UV-VIS spectrophotometry (from [...] which optical parameters such as band gap was derived), XRD, morphological surface analysis (AFM) and photocatalytic activity. The majority of the obtained thin films parameters were similar independent of the acid type and the ageing time of the gel. Nevertheless, a visible effect of the surface morphology properties on the films and their photocatalytic activity was observed.

Liana Key Okada, Nakamura; Jorge Moreira, Vaz.

1173-11-01

207

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

2010-08-01

208

Novel nanostructured mesoporous ZrO2/TiO2-based thin films for photooxidative decomposition of 2,4-dinitroaniline  

International Nuclear Information System (INIS)

Transparent mesoporous TiO2 and TiO2/ZrO2 mixed-oxide thin films are prepared via the template-assisted sol-gel method with attempt to enhance the decomposition reaction rate of industrial water pollutants. The results obtained indicate that the Zr addition retards film's sintering, improves the stability of a mesostructure during the thermal treatment causing the high roughness and developed surface area of samples. It is found that templated films showed higher photocatalytic activity than nonporous ones

209

Alternative to classic annealing treatments for fractally patterned TiO2 thin films  

International Nuclear Information System (INIS)

Titanium dioxide thin films have been deposited by reactive magnetron sputtering on glass and subsequently irradiated by UV radiation using a KrF excimer laser. The influence of the laser fluence (F) on the constitution and microstructure of the deposited films is studied for 0.052. The diffraction data reveal that as deposited films are amorphous, while irradiated films present an anatase structure. Additional Raman spectroscopy study shows better crystal quality for the films irradiated with F2. The film morphology appears to be strongly modified after laser treatment. Atomic force microscopy and scanning electron microscopy measurements reveal fractally textured films presenting characteristics of high porosity and high specific surface area. Finally, contact angle analysis suggests hydrophobic or wetting behavior depending on F. In order to explain the laser-induced structuration mechanisms, we have successfully applied a fractal as well as the nucleation theories. We propose that electronics effects could be responsible for the observed crystallization

210

Optical and morphological characterization of photocatalytic TiO2 thin films doped with silver  

International Nuclear Information System (INIS)

Silver-doped titanium dioxide thin films were deposited on glass substrates by the sol-gel process. Undoped films and films doped with 1 and 3 mol% Ag were annealed at 100 or 500 oC. The optical and morphological properties of the films were analyzed by optical absorption spectroscopy and scanning electron microscopy. Additionally, the films were evaluated for their ability to degrade methylene blue. It was found that the photocatalytic activity is barely sensitive to silver doping for films annealed at 100 oC, whereas the effect of silver resulted in enhanced photocatalytic activity for films annealed at 500 oC. For the latter annealing temperature, the photocatalytic activity increased with increasing Ag doping concentration.

211

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

International Nuclear Information System (INIS)

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

212

Preparation and photo-induced superhydrophilicity of composite TiO 2-SiO 2-In 2O 3 thin film  

Science.gov (United States)

In this work, TiO 2-SiO 2-In 2O 3 composite thin films on glass substrates were prepared by the sol-gel dip coating process. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the structural and chemical properties of the films. UV-vis spectrophotometer was used to measure the transmittance spectra of thin films. The water contact angle (WCA) of thin films during UV/vis irradiation and storage in a dark place was measured by a contact angle analyzer. The results indicated that fabrication of composite film has a significant effect on transmittance and superhydrophilicity of TiO 2 films.

Eshaghi, A.; Pakshir, M.; Mozaffarinia, R.

2010-09-01

213

Atomic layer deposition of photocatalytic TiO2 thin films from TiF4 and H2O.  

Science.gov (United States)

Titanium dioxide (TiO2) thin films were grown by atomic layer deposition (ALD) at 300-500 degrees C using TiF4 and H2O as precursors. The films were characterized by FESEM, EDX, UV/Vis and XRD techniques. Two glass types, soda lime and borosilicate, were used as the substrate materials. It was found that the type of the glass substrate had a very strong influence on the growth and properties of the resulting films. At substrate temperatures of 400 and 500 degrees C, the growth rates on borosilicate were 0.8 and 1.0 A per cycle, respectively, and the films were mainly anatase. With the same deposition conditions on soda lime, rutile phase was formed and the growth rates were 1.1 and 1.5 A per cycle, respectively. Growth saturation was confirmed for both glass substrates at 400 degrees C by varying the pulse lengths of the precursors. Both anatase and rutile films prepared at 400-500 degrees C possessed photocatalytic activity in degrading stearic acid under UV and visible light, whereas the films prepared at 300 degrees C had virtually no activity. All the films, including those prepared at 300 degrees C, turned superhydrophilic under UV light. PMID:19002335

Pore, Viljami; Kivelä, Tiina; Ritala, Mikko; Leskelä, Markku

2008-12-01

214

Investigation of Inhomogeneity of TiO2 Thin Films Using Spectroscopic Ellipsometry  

International Nuclear Information System (INIS)

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

215

Photocatalytic removal of hazardous Ponceau S dye using Nano structured Ni-doped TiO2 thin film prepared by chemical method  

Science.gov (United States)

Many attempts have been made by researchers for the removal of various dyes using nano structured Ni-doped TiO2; however, removal of `hazardous Ponceau S dye' using nano structured Ni-doped TiO2 has been not studied yet. In the present work, environmental application of Nano structured Ni doped TiO2 has been studied. Nano structured Ni-doped TiO2 thin films were deposited by the chemical method on a glass substrate. The prepared thin film was characterized by XRD, SEM, and EDX. The crystal size calculated from XRD is about 26.2 nm. The SEM analysis reveals nano spherical morphology of average particle size about 92 nm. The optical analysis was carried by using UV-visible spectroscopy. The band gap estimated from absorbance spectra for thin film was around 3.5 eV, making suitable Ni-doped TiO2 for photocatalytic removal of hazardous Ponceau S dye. In photocatalytic application different parameters like dye concentration, contact time, pH, UV light and sunlight were optimized for the removal of Ponceau S dye, respectively. The change in chemical oxygen demand after photo catalytic treatment was also studied.

Marathe, Sunil D.; Shrivastava, Vinod S.

2015-02-01

216

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

International Nuclear Information System (INIS)

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

217

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)

218

Tunable optical properties of hybrid inorganic-organic [(TiO2)m(Ti-O-C6H4-O-)k]n superlattice thin films.  

Science.gov (United States)

A combined atomic layer deposition (ALD) and molecular layer deposition (MLD) process was developed to fabricate inorganic-organic [(TiO2)m(Ti-O-C6H4-O-)k]n thin films from TiCl4, water and hydroquinone (HQ) precursors, and in particular, superlattice structures where single-molecular organic layers (k = 1) are periodically sandwiched between thicker TiO2 layers (m > 1). The incorporation of organic layers was found to systematically blue-shift the optical band gap of TiO2 with decreasing superlattice period and - most importantly - to sensitize the TiO2 layers to visible light over a considerable part of the visible range below 700 nm, a fact that could be of substantial interest for photocatalysis and solar cell applications. PMID:25380487

Niemelä, Janne-Petteri; Karppinen, Maarit

2014-12-01

219

Localized switching mechanism in resistive switching of atomic-layer-deposited TiO2 thin films  

Science.gov (United States)

The resistance switching mechanism of TiO2 films under voltage sweep mode was investigated. From the observed soft set of Pt /TiO2/Pt sample and from the polarity-dependant switching behavior of Ir(O )/TiO2/Pt sample, local rupture and recovery of conducting filaments near the anode interface wer identified as the switching mechanism. This is consistent with the authors' recent observation [K. Kim et al., Electrchem. Solid-State Lett. 9, G343 (2006)] of the resistance switching property of Al2O3/TiO2 multilayers, where switching was controlled by the layer close to the anode. It appears that most parts of the filaments are preserved during switching and only a small portion of the film near the anode contributes to switching.

Kim, Kyung Min; Choi, Byung Joon; Hwang, Cheol Seong

2007-06-01

220

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.

221

Effect of compressed TiO2 nanoparticle thin film thickness on the performance of dye-sensitized solar cells  

Science.gov (United States)

In this study, dye-sensitized solar cells (DSSCs) were fabricated using nanocrystalline titanium dioxide (TiO2) nanoparticles as photoanode. Photoanode thin films were prepared by doctor blading method with 420 kg/cm2 of mechanical compression process and heat treatment in the air at 500°C for 30 min. The optimal thickness of the TiO2 NP photoanode is 26.6 ?m with an efficiency of 9.01% under AM 1.5G illumination at 100 mW/cm2. The efficiency is around two times higher than that of conventional DSSCs with an uncompressed photoanode. The open-circuit voltage of DSSCs decreases as the thickness increases. One DSSC (sample D) has the highest conversion efficiency while it has the maximum short-circuit current density. The results indicate that the short-circuit current density is a compromise between two conflict factors: enlargement of the surface area by increasing photoanode thickness and extension of the electron diffusion length to the electrode as the thickness increases. PMID:24192482

2013-01-01

222

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

International Nuclear Information System (INIS)

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

223

Initial stages of TiO 2 thin films MOCVD growth studied by in situ surface analyses  

Science.gov (United States)

In situ chemical surface analyses using X-ray photoelectron spectroscopy (XPS) were performed to understand the initial stages of TiO 2 thin-film MOCVD growth. Deposits on Si (1 0 0), a few nanometres thick, were obtained at a fixed temperature of 650 °C and for two different pressures, 2.9 and 0.05 mbar, using titanium tetraisopropoxide (TTIP) as precursor. Pressure lowering led to a higher deposit growth rate. Reduction of titanium with respect to stoichiometric titanium dioxide and oxidation of the wet-cleaned silicon substrate are observed from decomposition of the Ti 2p and Si 2p peaks. The formation of a TiSi xO y mixed oxide is also pointed out and confirmed by the presence of a characteristic component in the O 1 s peak.

Brevet, A.; Peterlé, P. M.; Imhoff, L.; Marco de Lucas, M. C.; Bourgeois, S.

2005-02-01

224

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

International Nuclear Information System (INIS)

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

225

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

International Nuclear Information System (INIS)

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

226

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

OpenAIRE

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

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

2010-01-01

227

Molecular Interaction of Thin Film Photosensitive Organic Dyes on TiO2 Surfaces  

OpenAIRE

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

Yu, Shun

2011-01-01

228

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

International Nuclear Information System (INIS)

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 EC 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)

229

Chemical vapor infiltration of photocatalytically active TiO2 thin films on glass microfibers  

OpenAIRE

Due to the high diffusivity of the chemical species, chemical vapor infiltration (CVI) is a suitable process for the conformal coverage of objects with large dimensions and complex shape geometry. Its large scale capacity and high reproducibility have made the technique favorable for the deposition of non-oxide ceramics. There are few works on other materials and metal-organic compounds are rarely used as molecular precursors. In this study we focus on the deposition of anatase thin films on ...

Sarantopoulos, Christos; Gleizes, Alain; Maury, Francis

2007-01-01

230

Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.  

Science.gov (United States)

TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol. PMID:15464814

Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

2004-11-15

231

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

International Nuclear Information System (INIS)

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 TiO22 powder.

232

Fabrication and characterization of TiO2 thin film prepared by a layer-by-layer self-assembly method  

International Nuclear Information System (INIS)

Titanium dioxide (TiO2) thin films assembled with TiO2 nanoparticles and oppositely charged polyelectrolytes or titanium (IV) bis(ammonium lactato) dihydroxide (TALH) were successfully fabricated via a layer-by-layer (LBL) self-assembly method at room temperature. Especially, by using the quartz crystal microbalance (QCM) to monitor the in-situ deposition phenomenon of TALH that is saturated and then separated from the film before and after the deposition of 30 s at low pH, the anatase TiO2 multilayer films fabricated with 30 s deposition in TALH adjusted to pH 2.5 showed a higher refractive index (ca. n = 1.75), a denser film growth, and a lower surface roughness (ca. 10.5 nm) than those of the films deposited in different conditions. This film showed a high transmittance in visible range for optical applications and photocatalytic properties by decomposing methyl orange molecules gradually according to UV irradiation time. In addition, as the pH of TALH was decreased from pH 5.5 to 2.0, the thickness of (TiO2 / TALH)3 film was increased from ca. 85 nm to ca. 442 nm

233

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 indicateotoreactors. 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

234

Prediction of TiO2 thin film growth on the glass beads in a rotating plasma chemical vapor deposition reactor.  

Science.gov (United States)

We calculated the concentration profiles of important chemical species for TiO2 thin film growth on the glass beads in the TTIP + O2 plasmas and compared the predicted growth rates of thin films with the experimental measurements. The film thickness profile depends on the concentration profile of TiO(OC3H7)3 precursors in the gas phase because TiO(OC3H7)3 is the main precursor of the thin film. The TTIP concentration decreases with time, while the TiO(OC3H7)3 concentration increases, and they reach the steady state about 2 approximately 3 sec. The growth rate of TiO2 film predicted in this study was 9.2 nm/min and is in good agreements with the experimental result of 10.5 nm/min under the same process conditions. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor. PMID:20358924

Kim, Dong-Joo; Kim, Kyo-Seon

2010-05-01

235

Preparation of TiO2/SnO2 thin films by sol-gel method and periodic B3LYP simulations.  

Science.gov (United States)

Titanium dioxide (TiO2) thin films are grown by the sol-gel dip-coating technique, in conjunction with SnO2 in the form of a heterostructure. It was found that the crystalline structure of the most internal layer (TiO2) depends on the thermal annealing temperature and the substrate type. Films deposited on glass substrate submitted to thermal annealing until 550 °C present anatase structure, whereas films deposited on quartz substrate transform to rutile structure at much higher temperatures, close to 1000 °C, unlike powder samples where the phase transition takes place at about 780 °C. When structured as rutile, the oxide semiconductors TiO2/SnO2 have very close lattice parameters, making the heterostructure assembling easier. The SnO2 and TiO2 have their electronic properties evaluated by first-principles calculations by means of DFT/B3LYP. Taking into account the calculated band structure diagram of these materials, the TiO2/SnO2 heterostructure is qualitatively investigated and proposed to increase the detection efficiency as gas sensors. This efficiency can be further improved by doping the SnO2 layer with Sb atoms. This assembly may be also useful in photoelectrocatalysis processes. PMID:24824227

Floriano, Emerson A; Scalvi, Luis V A; Saeki, Margarida J; Sambrano, Julio R

2014-08-01

236

Investigation of Solar Energy Transfer through Plasmonic Au Nanoparticle-doped Sol-derived TiO2 Thin Films in Photocatalysis and Photovoltaics  

Science.gov (United States)

Titanium Dioxide (TiO2) films were elaborated using the Sol-Gel technique and subsequently used to study plasmonic photovoltaic and photocatalytic energy transfer enhancement mechanisms. TiO2 was chosen because of the unique optical and electrical properties it possesses as well as its ease of preparation and operational stability. The properties of sol-elaborated films vary significantly with processing environment and technique, and the sol formula; a systematic investigation of these variables enabled the selection of a consistent technique to produce relatively dense, crack-free TiO2 thin films. Localized Surface Plasmon Resonance (LSPR) energy transfer was investigated by integrating plasmonic Au nanoparticles into multi-layer wide-band gap semiconductor (TiO2) devices, and by doping strongly catalytic TiO2 anodes in a 3-electrode photochemical cell. An instant 3x photocurrent enhancement in the multilayer solar cell device was observed under 650nm light illumination, which suggests the presence of a resonant energy transfer. The focus of this work was to develop a systematic analysis of the actual mechanics of energy transfer responsible for the light-harvesting enhancements seen in previous studies of Au nanoparticle-TiO2 systems under visible illumination. This mechanism remains the subject of debate and models have been proposed by various researchers. A method is developed here to pinpoint the most influential of the proposed mechanisms.

Zelinski, Andrew

237

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

OpenAIRE

Photoinduced SO2 fixation on anatase TiO2 films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO2 films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO2 gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO...

Topalian, Zareh; Niklasson, Gunnar A.; Granqvist, Claes-go?ran; O?sterlund, Lars

2012-01-01

238

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

International Nuclear Information System (INIS)

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)

239

Reliability of ultra-thin titanium dioxide (TiO2) films on strained-Si  

International Nuclear Information System (INIS)

Ultra-thin high-k titanium oxide (equivalent oxide thickness ? 2.2 nm) films have been deposited on strained-Si/relaxed-Si0.8Ge0.2 heterolayers using titanium tetrakis iso-propoxides (TTIP) as an organometallic source at low temperature (2 gate dielectric during constant current (CCS) and voltage stressing (CVS) has been investigated. Normalized trapping centroid and trapped charge density variation with injected fluences have been investigated and also empirically modeled. Oxide lifetime is predicted using empirical reliability model developed. Dielectric breakdown and reliability of the dielectric films have been studied using constant voltage stressing. A high time-dependent dielectric breakdown (TDDB, tbd > 1000 s) is observed under high constant voltage stress

240

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

241

Photocatalytic oxidation of gaseous DMF using thin film TiO2 photocatalyst.  

Science.gov (United States)

The heterogeneous photocatalytic oxidation of gaseous N,N'-dimethylformamide (DMF) widely used in the manufacture of synthetic leather and synthetic textile was investigated. The experiments were carried out in a plug flow annular photoreactor coated with Degussa P-25 TiO2. The oxidation rate was dependent on DMF concentration, reaction temperature, water vapor, and oxygen content. Photocatalytic deactivation was observed in these reactions. The Levenspiel deactivation kinetic model was used to describe the decay of catalyst activity. Fourier transform infrared (FTIR) was used to characterize the surface and the deactivation mechanism of the photocatalyst. Results revealed that carbonylic acids, aldehydes, amines, carbonate and nitrate were adsorbed on the TiO2 surface during the photocatalytic reaction. The ions, NH4+ and NO3-, causing the deactivation of catalysts were detected on the TiO2 surface. Several treatment processes were applied to find a suitable procedure for the regeneration of catalytic activity. Among these procedures, the best one was found to be the H2O2/UV process. PMID:15664614

Chang, Chiu-Ping; Chen, Jong-Nan; Lu, Ming-Chun; Yang, He-Yuan

2005-02-01

242

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

Science.gov (United States)

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

Shubham, Kumar; Chakrabarti, P.

2014-05-01

243

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

International Nuclear Information System (INIS)

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

244

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

International Nuclear Information System (INIS)

Titanium dioxide thin films with good dielectric properties were obtained on Si substrates using the sol-gel method. The metal oxide films were deposited by spin coating from sol solution and additionally annealed at 600 C and 850 C. XRD analysis, FTIR and Raman spectroscopy were used for revealing the film structure, the crystal phases and the formation of a polycrystalline material. The electrical measurements on metal-insulator-silicon (MIS) structures showed good dielectric properties. An optimal regime for high temperature annealing (850 C/15 min) was found, for which no effects related to the thermal instability of TiO2 film on Si were observed. The leakage current density of a 38-nm thick TiO2 film annealed at 850 C/15 min/O2 was approximately 1.95x10-9 A/cm2 at 1.6x10-6 V/cm.

245

Cr-Doped TiO2 Thin Films Prepared by Means of a Magnetron Co-Sputtering Process: Photocatalytic Application  

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Full Text Available This paper deals with the effect of Cr content on photocatalytic activity of TiO2 thin films deposited on quartz and intrinsic silicon substrates by using the RF magnetron co-sputtering process. Some physical investigations on such sputtered films were made by means of X-ray Diffraction (XRD, atomic force microscopy (AFM, Raman spectroscopy as well as UV-Vis-IR absorption techniques. The heat treatment under oxygen atmosphere at 550°C reveals that the crystalline structure of TiO2: Cr depends on Cr content. Anatase-to-rutile phase transformation occurs at a Cr content of about 7%. On the other hand, the band gap energy value of annealed TiO2: Cr films varies in terms of Cr doping and a transition around 7% of Cr is accrued. The photocatalytic activity of undoped and doped TiO2 films was evaluated by photo-degrading of the amido black under UV light irradiation. Modification of the chemical structure of titanium dioxide by Cr doping allows moving the photocatalytic activity of titanium dioxide towards visible light. The results indicate that films doped with 2% Cr exhibit the highest UV and visible light photocatalytic activity.

Anouar Hajjaji

2014-06-01

246

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.)

247

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

International Nuclear Information System (INIS)

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

248

Hydrogen Bonding, H-D Exchange, and Molecular Mobility in Thin Water Films on TiO2(110)  

Science.gov (United States)

Hydrogen bonding, H-D exchange, and molecular mixing in water films on TiO2(110) have been studied using water electron-stimulated desorption. For T70K, H-D and molecular exchange between these “layers” occur with a distribution of activation energies and is surprisingly efficient. The results demonstrate that all the water molecules that are directly bound to TiO2(110)—i.e., in the first and second monolayers—are also hydrogen bonded to each other.

Petrik, Nikolay G.; Kimmel, Greg A.

2007-11-01

249

Raman spectroscopy of TiO2 thin films formed by hybrid treatment for biomedical applications.  

Science.gov (United States)

The paper presents the results of the investigations of the surface layer obtained after application of the combined hybrid method of oxidation in a fluidized bed (FB) and deposition of the oxide coating by PVD technique. The material used in the study was Ti Grade 2. The process of diffusive saturation was carried out in a fluidized-bed reactor at the temperature of 640°C for 8h in air while the top oxide layer was obtained through PVD method - magnetron sputtering using TiO2 target and argon atmosphere with the pressure of 3×10(-2)mbar and the distance between the substrate to the target of 60mm. In order to determine changes in the properties that occur as a result of modification of the Ti surface, the following examinations were carried out by SEM-EDX, X-ray diffraction methods, Raman spectroscopy, Glow Discharge Optical Spectroscopy (GDOS) and Secondary Ion Mass Spectrometry (SIMS). The coatings obtained were characterized by zonal structure comprising the solution zone of Ti?(O) and oxide zone of TiO2 with modifications of rutile and anatase, depending on the oxidation method. It was found that formation of oxide layers using the hybrid method (FB+PVD) leads to limitation of defects in the oxide layer after fluidized-bed thermal treatment and obtaining a uniform, tight coating with improved corrosion properties which are important from the biomedical standpoint. PMID:25037440

Lubas, M; Jasinski, J J; Sitarz, M; Kurpaska, L; Podsiad, P; Jasinski, J

2014-12-10

250

Structural and morphological properties of TiO2thin films prepared by spray pyrolysis  

Directory of Open Access Journals (Sweden)

Full Text Available En el presente trabajo la técnica de roc?o pirol?tico fue empleada para producir pel?culas delgadas de TiO2 sobre substratos de cuarzo y silicio cristalino (Si. Generado por ultrasonido, un aerosol de di-isopropoxido de titanio fue usado como precursor en los depósitos. El proceso de cristalización como función de los parámetros de deposito fue estudiado por difracción de rayos-X (XRD, espectroscop?a Rama (RS, microscopia de fuerza atómica (AFM y espectroscop?a óptica de transmisión (TS. Los resultados demuestran que la técnica de roc?o pirol?tico puede producir pel?culas con superficies planas y buenas propiedades cristalinas. Cuando la temperatura de depósito es menor a 400±C, la pel?cula crece con una superficie suave (rugosidad»5 ° A pero en una fase amorfa; sin embargo a temperaturas iguales a 400±C o mayores las pel?culas cristalizan en la fase anatasa aun cuando la rugosidad se incrementa hasta un valor que depende del espesor. Después de un tratamiento térmico a 750±C, las muestras depositadas sobre Si muestran una transicion parcial a la fase rutilio del TiO2con orientación preferencial (111; sin embargo, las pel?culas depositadas sobre cuarzo no muestran tal transicion.

N. Castillo

2004-01-01

251

Controlling the Al-doping profile and accompanying electrical properties of rutile-phased TiO2 thin films.  

Science.gov (United States)

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

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

2014-05-28

252

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

International Nuclear Information System (INIS)

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

253

Effects of dip-coating speed and annealing temperature on structural, morphological and optical properties of sol-gel nano-structured TiO2 thin films  

Science.gov (United States)

We reported material characterization of the nano-structured TiO2 thin films prepared by the sol-gel dip-coating process on glass substrates. The dependence of the structural, morphological and optical properties of the synthesized films on the fabrication parameters such as withdrawal velocity and annealing temperature were investigated by the techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectrophotometry. The results indicate that for the TiO2 films annealed at 500 °C there exhibits (1 0 1) XRD peak corresponding to the anatase phase of TiO2. The latter is consistent with the recorded Raman signal observed at 142 cm-1 (Eg mode) and 391 cm-1 (B1g mode), respectively. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films would depend on the withdrawal speed and the heat treatment temperature. The UV-visible spectroscopy analyses show that all the films were transparent in the visible region with an average transmittance of more than 70%. With an increase on the dip-coating speed from 1 cm/min to 3 cm/min, we observed a spectral red shift of the absorption edge from 3.76 eV to 3.71 eV, indicating a decrease in the bandgap energy (Eg) of the films.

Touam, Tahar; Atoui, Mohamed; Hadjoub, Ilhem; Chelouche, Azeddine; Boudine, Boubekeur; Fischer, Alexis; Boudrioua, Azzedine; Doghmane, Abdellaziz

2014-09-01

254

Vibrational relaxation dynamics of catalysts on TiO2 Rutile (1 1 0) single crystal surfaces and anatase nanoporous thin films  

International Nuclear Information System (INIS)

Highlights: • Investigated vibrational relaxation dynamics of a CO2-reduction catalyst on TiO2 surfaces. • IR pump-vibration sum-frequency generation probe spectroscopy on Rutile (1 1 0) surface. • IR-pump/IR probe transient absorption spectroscopy on nano-crystalline thin films. • CO stretching modes show a ultrafast population equilibration followed by population decay. - Abstract: Time-resolved vibrational sum frequency generation (VSFG) spectroscopy has been used to investigate the vibrational relaxation dynamics of the rhenium bipyridyl CO2-reduction catalyst Re(CO)3Cl(dcbpy) [dcbpy = 4,4?-dicarboxy-2,2?-bipyridine] adsorbed onto the (1 1 0) surface of a Rutile TiO2 single crystal. IR pump-VSFG probe spectra of the a?(1) CO stretching mode indicate a ultrafast population equilibration between three CO stretching modes followed by their population relaxation via intramolecular vibrational energy transfer. Similar vibational relaxation dynamics was also observed for the same complex on anatase TiO2 nanocrystalline thin films measured by IR pump-IR probe transient absorption spectroscopy. The relaxation dynamics of ReCOA on TiO2, in DMF solution, and immobilized on Au through alkane thiol linkers were compared to examine possible effects of adsorbate-TiO2 interaction

255

Crystalline nanoporous metal oxide thin films by post-synthetic hydrothermal transformation: SnO2 and TiO2  

Science.gov (United States)

Nanostructured and nanoporous metal oxide thin films are rarely accessible by standard synthetic approaches but highly desired for many applications, e.g. as electrodes, transparent conducting coatings, sensors or surface catalysts. Template based sol-gel chemistry combined with post-synthetic hydrothermal treatment allows now the synthesis of nanocrystalline mesostructured porous thin films of metal oxides, e.g. tin oxide and titania. Even in cases where the crystallization cannot be induced highly stable thin films can be achieved, e.g. niobium oxide thin films. We demonstrate how the size of the nanocrystallites influences and stabilizes the mesostructure at temperatures as low as 100 °C and thereby in the case of titania or tin dioxide even prevents it from deterioration at higher temperatures up to 400-600 °C.Nanostructured and nanoporous metal oxide thin films are rarely accessible by standard synthetic approaches but highly desired for many applications, e.g. as electrodes, transparent conducting coatings, sensors or surface catalysts. Template based sol-gel chemistry combined with post-synthetic hydrothermal treatment allows now the synthesis of nanocrystalline mesostructured porous thin films of metal oxides, e.g. tin oxide and titania. Even in cases where the crystallization cannot be induced highly stable thin films can be achieved, e.g. niobium oxide thin films. We demonstrate how the size of the nanocrystallites influences and stabilizes the mesostructure at temperatures as low as 100 °C and thereby in the case of titania or tin dioxide even prevents it from deterioration at higher temperatures up to 400-600 °C. Electronic supplementary information (ESI) available: Methods-detailed description of applied synthesis and characterization methods, Fig. S1-XRD wide angle data for titania after psHT and calcination, Fig. S2-XPS spectra of mesoporous titania thin films, Fig. S3-nitrogen physisorption measurements of Nb2O5 (A), TiO2 (B), SnO2 (C) thin films scratched of wafers, Fig. S4-PSD from EP measurements of Nb2O5 (A), TiO2 (B), SnO2 (C) thin films, and Fig. S5-photo of glass slides with thin films of Nb2O5 (A), TiO2 (B), SnO2 (C), empty (D) for transparency comparison. See DOI: 10.1039/c0nr00079e

Shao, Shaofeng; Dimitrov, Momtchil; Guan, Naijia; Köhn, Ralf

2010-10-01

256

Effect of an Al2O3/TiO2 Passivation Layer on the Performance of Amorphous Zinc-Tin Oxide Thin-Film Transistors  

Science.gov (United States)

The effect of an Al2O3/TiO2 stacked passivation layer on the performance of amorphous ZnSnO ( a-ZTO) thin-film transistors (TFTs) was investigated by comparing field-effect mobility ( ? FE) and subthreshold swing after passivation layer deposition. The values observed were 4.7 cm2/Vs and 0.64 V/decade, respectively, for uncoated TFTs and 4.6 cm2/Vs and 0.62 V/decade for passivated TFTs. In addition, excellent water vapor transmission was observed for electron beam-irradiated Al2O3/TiO2-passivated poly(ether sulfone) substrates in a humidity test, because the Al2O3/TiO2 passivation layer can enhance the interface properties between Al2O3 and TiO2. To investigate the origin of this enhancement, we performed x-ray photoelectron spectroscopy of both unpassivated and Al2O3/TiO2-passivated TFTs with a-ZTO back-channel layers after Ar annealing.

Han, Dong-Suk; Park, Jae-Hyung; Kang, Min-Soo; Shin, So-Ra; Jung, Yeon-Jae; Choi, Duck-Kyun; Park, Jong-Wan

2015-02-01

257

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

International Nuclear Information System (INIS)

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

258

Wet Etching of Amorphous TiO2 Thin Films Using H3PO4-H2O2 Aqueous Solution  

Science.gov (United States)

We report on the wet etching of amorphous undoped and Nb-doped TiO2 thin films using H3PO4-H2O2 etching solution. The etching rate (R) showed a maximum at a H3PO4 concentration of approximately 50 wt % at 80 °C, suggesting that H2PO4- and/or H3O+ is responsible for the etching reaction. The addition of H2O2 to H3PO4 solution significantly enhanced R, and an optimized solution exhibited an R of 13 nm/min at 80 °C, which is one order of magnitude higher than that using H2SO4. These results demonstrate that H3PO4-H2O2 aqueous solution is an effective etchant for TiO2-based amorphous thin films.

Okazaki, Sohei; Ohhashi, Takuya; Nakao, Shoichiro; Hirose, Yasushi; Hitosugi, Taro; Hasegawa, Tetsuya

2013-09-01

259

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

International Nuclear Information System (INIS)

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

260

Synthesis of TiO2 nanotube array thin films and determination of the optical constants using transmittance data  

Science.gov (United States)

TiO2 nanotube arrays were grown on glass substrate by ZnO nanorod sol-gel template process. XRD analysis and FESEM microscopy were employed to characterize the structural and morphological properties of the prepared nanotube. EDX and UV-Vis spectroscopy were used to assess the chemical composition and study the optical properties of the film. An optical model has been performed to simulate the optical constants and thicknesses of the films from transmittance data using the Levenberg-Marquardt algorithm via Drude model. The simulated transmittance is in good agreement with the measured spectrum in the whole measurement wavelength range. The refractive index and extinction coefficient, thickness and dielectric function of TiO2 nanotube films were calculated by Drude model. Also, the related absorption coefficient, optical bandgap and porosity were determined.

Ahmadi, K.; Abdolahzadeh Ziabari, Ali; Mirabbaszadeh, K.; Ahmadi, S.

2015-01-01

261

Non-adiabatic small polaron hopping conduction in Nb-doped TiO2 thin film  

International Nuclear Information System (INIS)

Transport properties of Nb-doped titanium oxide (TiO2) thin film, obtained by a RF sputtering technique, have been investigated by means of the electrical conductivity and the Seebeck coefficient as a function of temperature (13-425 K). At high temperatures (T>325 K), temperature dependent behaviors of the electrical conductivity and the Seebeck coefficient confirm that the transport mechanism is the non-adiabatic small polaron hopping type. An excellent agreement between the theoretical and the experimental values of non-adiabatic polaron hopping energy (WH?0.3 eV) is obtained. The conductivity follows the Mott's variable range hopping conduction (VRH) at the temperature range of 200-325 K, while it exhibits a temperature-independent behavior at low temperatures (T<200 K). Various physical parameters of the present sample such as polaron radius, effective dielectric constant, polaron hopping energy, density of states at the Fermi level, polaron band width and polaron coupling constant are determined using small polaron hopping model.

262

Solar absorption and microstructure of C-doped and H-co-doped TiO2 thin films  

International Nuclear Information System (INIS)

This work examined the effect of different levels of C doping on the microstructure and optical properties of TiO2 thin films consisting of mostly rutile and amorphous phases. The increase in the substitutional C doping from 0.32 to 8.57 at% was found to reduce the long-range order through the refinement of the crystalline phase, and increases in the concentration of the extended defects and fraction of the disordered phase, where C gets segregated due to its low solubility in the crystalline phase. As expected, the main absorption threshold red-shifted with the increase in C doping (from 3.22 to 2.48 eV) and additional thresholds existed in the visible and NIR ranges. However, at the same time only a small reduction in the separation between the extended states (by up to 0.27 eV) was achieved. The significant increase in the visible absorption originated mostly from the C-induced spread of localized states within the band gap. Higher levels of C doping introduce localized states deeper into the band gap, which may increase the carrier recombination as well. Co-doping with hydrogen nearly fills the band gap with localized states and further increases the visible and NIR absorption.

263

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

264

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

International Nuclear Information System (INIS)

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

265

Photocatalytic degradation of glyphosate in water by N-doped SnO2/TiO2 thin-film-coated glass fibers.  

Science.gov (United States)

Photocatalytic degradation of glyphosate contaminated in water was investigated. The N-doped SnO2/TiO2 films were prepared via sol-gel method, and coated on glass fibers by dipping method. The effects of nitrogen doping on coating morphology, physical properties and glyphosate degradation rates were experimentally determined. Main variable was the concentration of nitrogen doping in range 0-40 mol%. Nitrogen doping results in shifting the absorption wavelengths and narrowing the band gap energy those lead to enhancement of photocatalytic performance. The near optimal 20N/SnO2/TiO2 composite thin film exhibited about two- and four-folds of glyphosate degradation rates compared to the undoped SnO2/TiO2 and TiO2 films when photocatalytic treatment were performed under UV and solar irradiations, respectively, due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and smallest crystallite size influenced by N-doping. PMID:25169246

Kongsong, Peerawas; Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

2014-01-01

266

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

OpenAIRE

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 ...

Kaneko, Masao; Ueno, Hirohito; Nemoto, Junichi

2011-01-01

267

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

International Nuclear Information System (INIS)

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

268

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)

269

Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates  

Science.gov (United States)

Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

Erakovi?, S.; Jankovi?, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Jana?kovi?, Dj.; Miškovic-Stankovi?, V.

2014-02-01

270

Hydrogen Bonding, H-D Exchange, and Molecular Mobility in Thin Water Films on TiO2(110)  

Energy Technology Data Exchange (ETDEWEB)

Hydrogen bonding, H/D exchange and diffusion in water films (? 2 monolayers) on TiO2(110) have been studied using water electron-stimulated desorption. For T < 70 K, films with one water isotope adsorbed on the Ti4+ rows and another isotope on the bridging oxygen rows can be prepared. For T > 70 K, H/D exchange and molecular diffusion between these “layers” occur with a distribution of activation energies. The results demonstrate that all the water molecules that are directly bound to TiO2(110) – i.e. water in the first and second layers – are also hydrogen bonded to each other, thus influencing the chemistry of the water/TiO2(110) interface.

Petrik, Nikolay G.; Kimmel, Greg A.

2007-11-09

271

Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation  

Science.gov (United States)

In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi; Liu, Bin; Cao, Baocheng

2014-08-01

272

Microstructure characterization of sol-gel prepared MoO3-TiO2 thin films for oxygen gas sensors  

International Nuclear Information System (INIS)

Binary metal-oxide MoO3-TiO2 films have been prepared using the sol-gel technique. The thin films were annealed at several temperatures including 400, 450, 500, 550, and 600 deg. C for 1 h. The morphology, crystalline structure, and chemical composition of the films have been analyzed using scanning electron microscopy (SEM) and atomic force microscopy, x-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and x-ray photoelectron spectroscopy (XPS) techniques. The SEM analysis showed that there are two different sizes of grains in the films annealed at temperatures of 400, 450, 500, and 550 deg. C. One grain type is small with 20-100 nm; the other is a large grain type several micrometers in length. The XRD analysis revealed that the films annealed at 400 deg. C were a mixture of orthorhombic and hexagonal MoO3 phases. The films annealed at 450 deg. C showed an increase in the hexagonal phase. A preferential orientation growth along the (100) plane of the hexagonal phase and the (010) plane of the orthorhombic phase has been found in both samples. RBS and XPS analysis showed that the films were stoichiometric. When the annealing temperature was increased beyond 500 deg. C, the concentration ratio of MoO3-TiO2 decreased due to the evaporation of MoO3. For the study of the electrical and gas sensing properties, the films were deposited on sapphire substrates with interdigital electrodes o substrates with interdigital electrodes on the frontside and a Pt heater on the backside. The MoO3-TiO2 thin films are sensitive to oxygen gas. The film has exhibited the O2 response (S=Rg/Rb) of 2.1, 8.1, and 80 for 120, 1000, and 10 000 ppm concentration of O2, respectively

273

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English 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 spectrosc [...] opy 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 associated 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.

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

2014-02-01

274

Very large anisotropy in the dc conductivity of epitaxial VO2 thin films grown on (011) rutile TiO2 substrates  

Science.gov (United States)

In this letter, we reported a very large anisotropy in dc conductivity of epitaxial VO2 thin films deposited on a (011) TiO2 substrate. The VO2 film grew epitaxially on TiO2 and x-ray diffraction showed that VO2 had the tetragonal symmetry due to the substrate clamping effect at room temperature. There was a compressive strain of -1.2% along the c-axis of the rutile VO2. We observed a very strong angular dependence of in-plane dc conductivity. We calculated that ?1/?3˜5.14, which was anomalously large. We attributed the drastic increase to the compressive strain along the c-axis of the rutile VO2 due to substrate clamping. This very large anisotropy disappeared above the metal-insulator transition.

Lu, Jiwei; West, Kevin G.; Wolf, Stuart A.

2008-12-01

275

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 foonditions 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

276

Formation mechanism of a microscale domain and effect on transport properties in strained VO2 thin films on TiO2(001)  

Science.gov (United States)

We investigated film thickness dependence of domain size and transport property in VO2 thin films on rutile TiO2 (001) substrates and identified formation mechanism of the microscaled domain. It was found that domain size decreased with increasing film thickness and the domain boundary consisted of cracks and dislocations, clarified by high-resolution transmission electron microscopy. The detailed images showed, the tensile-strained VO2 lattices received by TiO2 (001) were partially relaxed around the cracks and dislocations. The relaxed lattice is likely to return the original metal-insulator transition temperature of 340 K, whereas the tensile-strained lattice has the transition at 300 K in a VO2/TiO2 (001) system. Thus, the mixed states of strained and relaxed crystal lattice and the increase in dislocation density in thicker films cause the overly broad resistance behavior against temperature. Furthermore, the origin of the dislocations and the thickness dependence of the domain size could be explained by the energy release of shear stress generated by competition between the pinning layers at near-interface VO2 layers holding the tetragonal structure and the near-surface layers separated from the substrate attempting the lattice transformation to a monoclinic structure. This understanding enables us to more precisely design the size and configuration of these domains and their transport properties.

Kawatani, Kenichi; Kanki, Teruo; Tanaka, Hidekazu

2014-08-01

277

Evidence of room temperature ferromagnetism in argon/oxygen annealed TiO2 thin films deposited by electron beam evaporation technique  

Science.gov (United States)

TiO2 thin films deposited by electron beam evaporation technique annealed in either O2 or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O2 atmosphere. While the pristine film shows a super-paramagnetic behavior, both O2 and Ar annealed films display hysteresis at 300 K. X-ray photo emission spectroscopy (XPS), Raman spectroscopy, Rutherford's backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were used to refute the possible role of impurities/contaminants in magnetic properties of the films. The saturation magnetization of the O2 annealed film is found to be higher than the Ar annealed one. It is revealed from shifting of O 1s and Ti 2p core level spectra as well as from the enhancement of high binding energy component of O 1s spectra that the higher magnetic moment is associated with higher oxygen vacancies. In addition, O2 annealed film demonstrates better crystallinity, uniform deposition and smoother surface than that of the Ar annealed one from glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM). We conclude that although ferromagnetism is due to oxygen vacancies, the higher magnetization in O2 annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO2 film deposited by pulsed laser deposition (Mohanty et al., 2012 [10]).

Mohanty, P.; Kabiraj, D.; Mandal, R. K.; Kulriya, P. K.; Sinha, A. S. K.; Rath, Chandana

2014-04-01

278

ELECTRONIC STRUCTURE OF TIO2 THIN FILMS AND LAALO3-SRTIO3 HETEROSTRUCTURES: THE ROLE OF TITANIUM 3D1 STATES IN MAGNETIC AND TRANSPORT PROPERTIES  

OpenAIRE

The scope of this Thesis is the study of the electronic structure of two Ti-based oxide systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO) heterojunctions, which display remarkable physical phenomena, so far not completely understood. In both cases, the titanium-related electronic states are expected to play a fundamental role and thus have been probed by means of X-ray photoemission spectroscopies. A weak room-temperature ferromagnetism (FM) has been recently detected i...

Drera, Giovanni

2012-01-01

279

Brookite TiO2 thin film epitaxially grown on (110) YSZ substrate by atomic layer deposition.  

Science.gov (United States)

Epitaxial brookite TiO2 (B-TiO2) film was deposited on (110) yttria-stabilized zirconia (YSZ) substrate using plasma-enhanced atomic layer deposition, and its structural, optical, and gas sensing properties were investigated. As-deposited TiO2 film was a pure brookite and (120) oriented. The determined in-plane orientation relationships were [21?0]B-TiO2//[1?10]YSZ and [001]B-TiO2 //[001]YSZ. The B-TiO2 film showed ?70% transmittance and the optical band gap energy was 3.29 eV. The B-TiO2 film-based gas sensor responded to H2 gas even at room temperature and the highest magnitude of the gas response was determined to be ?150 toward 1000 ppm of H2/air at 150 °C. In addition, B-TiO2 sensor showed a high selectivity for H2 against CO, EtOH, and NH3. PMID:25007217

Kim, Dai-Hong; Kim, Won-Sik; Kim, Sungtae; Hong, Seong-Hyeon

2014-08-13

280

Crystallographic phase control of TiO2 in thin films deposited by asymmetric bipolar pulsed DC sputtering  

Science.gov (United States)

The asymmetric bipolar pulsed DC sputtering system has been tuned for obtaining selective crystallographic phase namely anatase and rultile structure of TiO2. This has been achieved by varying oxygen partial pressure and total pressure during deposition. The deposited films were characterized by grazing incident x-ray diffraction and Raman scattering. Our investigations inferred a very systematic evolution of anatase phase over rutile phase as a function of oxygen partial pressure. The results are explained on the basis of energy consideration of sputtered species and its influence at the substrate surface temperature.

Sagdeo, P. R.; Maidul, Sekh; Shinde, D. D.; Misal, J. S.; Thakur, S.; Sahoo, N. K.; Sagdeo, A.; Rai, S.; Mukherjee, C.; Rajiv, K.; Sathe, V. G.; Gupta, M.

2012-06-01

281

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

Directory of Open Access Journals (Sweden)

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

Masao Kaneko

2011-02-01

282

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

International Nuclear Information System (INIS)

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

283

Synthesis and characterization of C-doped TiO2 thin films for visible-light-induced photocatalytic degradation of methyl orange  

Science.gov (United States)

C-TiO2 thin films were synthesized by a modified sol-gel route based on the self-assembly technique exploiting Tween80 (T80) as a pore directing agent and carbon source. The effect of calcination time on the photocatalytic activity of C-doped TiO2 catalyst was studied. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FTIR), UV-vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). The XRD results showed that C-TiO2 sample calcined at 400 °C for various times exhibited anatase phase and no other crystal phase was identified. C-TiO2 exhibited a shift in an absorption edge of samples in the visible region than that of conventional or reference TiO2. The XPS results showed an existence of C in the TiO2 catalysts and C might be existed as COTi group. Moreover, the C-TiO2 thin film calcined at 400 °C for 30 min showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under UV light irradiation. Also the photocatalytic activity of synthesized catalyst was evaluated by decomposition of methyl orange (MO) under visible light irradiation. The results showed that the optimum preparations of C-TiO2 thin films were found to be under calcination temperature of 400, calcination time of 30 min, and with preparation 9 layers film.

Hassan, Mohamed Elfatih; Cong, Longchao; Liu, Guanglong; Zhu, Duanwei; Cai, Jianbo

2014-03-01

284

Enhanced capacitance performance of Al2O3-TiO2 composite thin film via sol-gel using double chelators.  

Science.gov (United States)

Titanium dioxide (TiO2) is usually introduced into dielectric layer of aluminum electrolytic capacitor to enhance capacitance performance via forming Al2O3-TiO2 composite film. However, there is a big obstacle caused by high crystallization temperature of TiO2 to capacitance enhancement. In present work, a facile route was proposed to synthesize crystalline TiO2 with the size of 3-10nm at room temperature using lactic acid (LA) and acetylacetone (Acac) as double chelators. After being introduced into the surface of etched aluminum foils as dielectric layer, TiO2 boosted the specific capacitance by about 24% compared to that without TiO2, and about 11% compared to that with TiO2 using lactic acid as only chelator. PMID:25554973

Du, Xianfeng; Men, Kai; Xu, Youlong; Li, Bing; Yang, Zhuo; Liu, Zihan; Li, Long; Li, Liang; Feng, Tianyu; Rehman, Wasif Ur; Ullah, Inam; Mao, Shengchun

2015-04-01

285

Initial growth mechanisms of ZrO2 and TiO2 thin films using cycloheptatrienyl–cyclopentadienyl heteroleptic precursors: A comparative study by density functional theory  

International Nuclear Information System (INIS)

The initial growth mechanisms of atomic layer deposition (ALD) of ZrO2 and TiO2 thin films using cycloheptatrienyl (CHT)–cyclopentadienyl (Cp) precursors on Si-OH surface have been investigated theoretically. The reactions of CpMeZr(CHT) and CpTi(CHT) with Si-OH surface proceed through similar reaction pathways. The reaction of CpTi(CHT) requires much more energies than that of CpMeZr(CHT). Chemisorption of the CHT–Cp precursors on Si-OH surface could not be found. The most stable adsorption states of both CpMeZr(CHT) and CpTi(CHT) are formed via CHT rings. The previous experiments have shown that an ALD-window has been established when depositing ZrO2 thin films, but has not been established when depositing TiO2 thin films. Our calculation results show that the adsorption of CpMeZr(CHT) is energetically favorable, but the adsorption of CpTi(CHT) is thermodynamic unfavorable. One theoretical explanation is given for this observed difference from the viewpoint of precursor adsorption.

286

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

287

Exploring a new phenomenon in the bactericidal response of TiO2 thin films by Fe doping: Exerting the antimicrobial activity even after stoppage of illumination  

Science.gov (United States)

Antibacterial properties of Fe-doped TiO2 thin films prepared on glass by the sol-gel hot-dipping technique were studied. The films were characterized by X-ray diffraction, field emission scanning electron microscopy, scanning probe microscopy and X-ray photoelectron spectroscopy. The photocatalytic activities were evaluated by measuring the decomposition rate of methylene blue under ultra violet and visible light. The antibacterial properties of the coatings were investigated against Escherichia coli, Staphylococcus aureus, Saccharomyces cerevisia and Aspergillus niger. The principle of incubation methods was also discussed. The results indicated that Fe doping of thin films eventuated in high antibacterial properties under visible light and this performance remained even after stoppage of illumination. This article tries to provide some explanation for this fact.

Naghibi, Sanaz; Vahed, Shohreh; Torabi, Omid; Jamshidi, Amin; Golabgir, Mohammad Hossein

2015-02-01

288

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English 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 aut [...] omatization software and electronics. To evaluate the ALD performance we used as precursor trymethyl aluminum (TMA) and tetrakis (dimethylamino) titanium (TDMAT) to deposit Al2O3 and TiO2, respectively, in nanolaminated film structures. The thicknesses and composition of the films are precisely controlled, as determined by spectroscopic ellipsometry, and the nanolaminates have a sharp interface as indicated by Auger depth profile.

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

2012-12-01

289

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

International Nuclear Information System (INIS)

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.

290

Investigation of localized surface plasmon/grating-coupled surface plasmon enhanced photocurrent in TiO2 thin films.  

Science.gov (United States)

We fabricated plasmonic gold nanoparticle (AuNP)-TiO2 nanocomposite films and measured the photocurrent that originates from the water-splitting reaction catalyzed by the AuNP-TiO2 nanocomposite photoelectrocatalytic (PEC) electrode. The localized surface plasmon resonance (LSPR) of the gold nanoparticles affected the generation of photocurrent by TiO2 upon illumination with visible light. Electrochemical impedance spectroscopy (EIS) revealed that the improvement in the photocurrent generation originates from an enhancement in electron-hole pair generation induced by the SPR of the plasmonic gold nanoparticles rather than the extension of the electron lifetime. Moreover, we introduced a novel method to enhance the photocurrent of TiO2 by a multiple plasmonic effect, i.e., LSPR of plasmonic gold nanoparticles and the grating-coupled propagating SP on a gold grating. We fabricated the AuNP-TiO2 nanocomposites on a gold-coated Blu-ray disc recordable (BD-R). The enhancement of the photocurrent due to the combination of LSPR and the grating-coupled SP was investigated. PMID:25308828

Nootchanat, Supeera; Ninsonti, Hathaithip; Baba, Akira; Ekgasit, Sanong; Thammacharoen, Chuchaat; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

2014-11-28

291

Photocatalytic antibacterial performance of glass fibers thin film coated with N-doped SnO2/TiO2.  

Science.gov (United States)

Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600 °C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency. PMID:24693250

Kongsong, Peerawas; Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

2014-01-01

292

Photocatalytic Antibacterial Performance of Glass Fibers Thin Film Coated with N-Doped SnO2/TiO2  

Science.gov (United States)

Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600°C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency. PMID:24693250

Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

2014-01-01

293

Evidence of room temperature ferromagnetism in argon/oxygen annealed TiO2 thin films deposited by electron beam evaporation technique  

International Nuclear Information System (INIS)

TiO2 thin films deposited by electron beam evaporation technique annealed in either O2 or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O2 atmosphere. While the pristine film shows a super-paramagnetic behavior, both O2 and Ar annealed films display hysteresis at 300 K. X-ray photo emission spectroscopy (XPS), Raman spectroscopy, Rutherford’s backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were used to refute the possible role of impurities/contaminants in magnetic properties of the films. The saturation magnetization of the O2 annealed film is found to be higher than the Ar annealed one. It is revealed from shifting of O 1s and Ti 2p core level spectra as well as from the enhancement of high binding energy component of O 1s spectra that the higher magnetic moment is associated with higher oxygen vacancies. In addition, O2 annealed film demonstrates better crystallinity, uniform deposition and smoother surface than that of the Ar annealed one from glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM). We conclude that although ferromagnetism is due to oxygen vacancies, the higher magnetization in O2 annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO2 film deposited by pulsed laser deposition (Mohanty et al., 2012 [10]). - Highlights: • TiO2 films were deposited by e-beam evaporation technique and post annealed under O2/Ar at 500 °C. • The pristine film shows SPM behavior where as O2 and Ar annealed films demonstrate RTFM. • The presence of magnetic impurities has been discarded by various characterization techniques. • The magnetic moment is found to be higher in O2 annealed film than the Ar annealed one. • The higher Ms in O2 annealed film is attributed to oxygen vacancies as well as crystallinity

294

Preparation and Electrical Properties of TiO2/SnO2 Nanocrystalline Films  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of SnO2 nanocrystalline coatings on the performance of dye-sensitized solar cells (DSSC based on TiO2-nanoparticle photoanode was studied. The TiO2-nanoparticle photoanode was prepared by screen-printing technique, and the SnO2 nanocrystalline films were coated on TiO2 nanoparticles by soaking TiO2 photoanodes in SnO2 solution with different concentrations or different time. SEM images indicate SnO2 nanocrystalline films have smaller surface grains than the TiO2 nanocrystalline films. The electrical properties of the films indicate that SnO2 thin films growing on the TiO2 films by soaking TiO2 films in 0.4 mol /L SnO2 solution for 50 min play a positive role on the structure and performance of the TiO2 films, and the conversion efficiency of the solar cell with TiO2/SnO2 photoanode is about 7% higher than that of TiO2 films.

CUI Xu-Mei, ZUO Cheng-Yang, LAN De-Jun, WANG Jun

2013-11-01

295

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

International Nuclear Information System (INIS)

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

296

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

OpenAIRE

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 amorp...

Tejos, M.; Buono-cuore, G. E.; Di?az, F. R.; Del Valle, M. A.; Palomares, J.

2004-01-01

297

Atomic rearrangements at the TiO2-terminated (001)SrTiO3 surface and growth of thin LaMnO3 films  

Science.gov (United States)

SrTiO3 is commonly used as a substrate for growth of various oxide films. Different reconstructions at the SrTiO3 surface have been claimed. A question is whether these survive subsequent depositions of thin films and influence film properties. Medium energy ion scattering (MEIS) was used to probe structure and composition of the surface layer of a TiO2-terminated (001)SrTiO3 single-crystal substrate and 1-4 unit cell (u.c.) thick LaMnO3 epilayers. Aligned spectra indicate enrichment of Ti at the surface and a TiO2 double-layer (DL) configuration. The DL arrangement survives pulsed-laser deposition of LaMnO3 in a background of high oxygen pressure (5 × 10-2 mbar) while it is destroyed at lower oxygen pressure (10-4 mbar). Simulations of random MEIS spectra indicate substantial interdiffusion and La doping of the substrate surface but all interfaces are nevertheless insulating.

Boikov, Yu. A.; Serenkov, I. T.; Sakharov, V. I.; Kalabukhov, A. S.; Aurino, P. P.; Winkler, D.; Claeson, T.

2013-06-01

298

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

Science.gov (United States)

Single and multilayer sol-gel thin films of Ti02-PbO, Ti02-Bi203 and Ti02-CeO2 composition were deposited on glasses using the dip coating technique. The precursors included Ti(OPri)4 chemically modified by acetyl acetone and diluted in PriOH and sols of Pb(OAc)2, Bi(NO3)3 5H20 diluted in acetic acid. The Ti02-Ce02 sol was prepared by mixing Ce NH2 (NO3 )6 in ethanol and then adding Ti (O-iso-C3H7 )4. Structure texture and homogeneity of their main constituants was established by XRD, XPS,SIMS and SEM-EDX techniques as a function of heat treatments.

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

1990-11-01

299

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

Directory of Open Access Journals (Sweden)

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

The-Vinh Nguyen

2009-01-01

300

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

Scientific Electronic Library Online (English)

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

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

2004-12-01

301

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.

302

The Effect of Tween® Surfactants in Sol-Gel Processing for the Production of TiO2 Thin Films  

Directory of Open Access Journals (Sweden)

Full Text Available Titanium dioxide thin films were deposited using a Tween® surfactant modified non-aqueous sol-gel method onto fluorine doped tin oxide glass substrates. The surfactant concentration and type in the sols was varied as well as the number of deposited layers. The as deposited thin films were annealed at 500 °C for 15 min before characterisation and photocatalytic testing with resazurin intelligent ink. The films were characterised using scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy and UV-Vis spectroscopy. Photocatalytic activity of the films was evaluated using a resazurin dye-ink test and the hydrophilicity of the films was analysed by water-contact angles measurements. Characterisation and photocatalytic testing has shown that the addition of surfactant in varying types and concentrations had a significant effect on the resulting thin film microstructure, such as changing the average particle size from 130 to 25 nm, and increasing the average root mean square roughness from 11 to 350 nm. Such structural changes have resulted in an enhanced photocatalytic performance for the thin films, with an observed reduction in dye half-life from 16.5 to three minutes.

Ann-Louise Anderson

2014-12-01

303

Evolution of structural and magnetic properties of Co-doped TiO2 thin films irradiated with 100 MeV Ag7+ ions  

Science.gov (United States)

In continuation to our earlier studies where we have shown room temperature ferromagnetism observed in TiO2 and Co-doped TiO2 (CTO) thin films independent of their phase (Mohanty et al 2012 J. Phys. D: Appl. Phys. 45 325301), here the modifications in structure and magnetic properties in CTO thin films using 100 MeV Ag7+ ion irradiation are reported. Owing to the important role of defects in tailoring the magnetic properties of the material, we vary the ion fluence from 5 × 1011 to 1 × 1012 ions cm-2 to create post-deposition defects. While the film deposited under 0.1 mTorr oxygen partial pressure retains its crystallinity showing radiation-resistant behaviour even at a fluence of 1 × 1012 ions cm-2, films deposited under 1 to 300 mTorr oxygen partial pressure becomes almost amorphous at the same fluence. Using Poisson's law, the diameter of the amorphized region surrounding the ion path is calculated to be ˜4.2 nm from the x-ray diffraction peak intensity ((1?1?0) for rutile phase) as a function of ion fluence. The saturation magnetization (Ms) decreases exponentially similar to the decrease in x-ray peak intensity with fluence, indicating magnetic disordered region surrounding the ion path. The diameter of the magnetic disordered region is found to be ˜6.6 nm which is larger than the diameter of the amorphized latent track. Therefore, it is confirmed that swift heavy ion irradiation induces a more significant magnetic disorder than the structural disorder.

Mohanty, P.; Singh, V. P.; Mishra, N. C.; Ojha, S.; Kanjilal, D.; Rath, Chandana

2014-08-01

304

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.

305

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

Science.gov (United States)

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

Chien Dang, Tran; Pham, Duy Long; Le, Ha Chi; Pham, Van Hoi

2010-03-01

306

Spectroscopic ellipsometry characterization of amorphous and crystalline TiO2 thin films grown by atomic layer deposition at different temperatures  

Science.gov (United States)

TiO2 thin films of widely different structural and morphological characteristics were grown on Si (1 0 0) substrates using Atomic Layer Deposition (ALD) by varying the substrate temperature (Ts) in a wide range (50 °C ? Ts ? 400 °C). Spectroscopic ellipsometry (SE) measurements were carried out to investigate the effect of growth temperature on the optical properties of the films. Measured SE data were analyzed by considering double layer optical model for the sample together with the single oscillator Tauc-Lorentz dispersion relation. Surface roughness was taken into consideration due to the columnar growths of grains in crystalline films. The refractive index was found to be increased from amorphous (Ts ? 150 °C) to the nanocrystalline films (2500 < Ts ? 400 °C). The pronounced surface roughening for the large-grained anatase film obtained at the amorphous to crystalline phase transformation temperature of 200 °C, impeded SE measurement. The dispersions of refractive indices below the interband absorption edge were found to be strongly correlated with the single oscillator Wemple-DiDomenico (WD) model. The increase in dispersion energy parameter in WD model from disordered amorphous to the more ordered nanocrystalline films was found to be associated with the increase in the film density and coordination number.

Saha, D.; Ajimsha, R. S.; Rajiv, K.; Mukherjee, C.; Gupta, M.; Misra, P.; Kukreja, L. M.

2014-10-01

307

Change of resistive-switching in TiO2 films with additional HfO2 thin layer  

International Nuclear Information System (INIS)

We have fabricated TiN/(HfO2)/TiO2/Pt/Ti stacks on SiO2/Si substrates and investigated the characteristics of the bipolar resistive switching of those stacks. Compared to the single TiO2 structure, more stable bipolar switching in the current-voltage curve was accomplished in the HfO2 /TiO2 structure. We obtained a smaller range of SET variation, a larger sensing margin, and higher resistance values of the high-resistance state with an additional HfO2 layer. Especially, in the case of the HfO2/TiO2 structure, the set voltage was decreased after O2 annealing. The heat treatment in an ambient of O2 and an additional HfO2 layer can improve the bipolar resistive switching behavior for resistive random access memory applications.

308

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

International Nuclear Information System (INIS)

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

309

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-01-01

310

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

311

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

2013-08-01

312

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

International Nuclear Information System (INIS)

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

313

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

International Nuclear Information System (INIS)

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

314

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.

315

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

Directory of Open Access Journals (Sweden)

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

F. Arefi-Khonsari

2011-01-01

316

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.

Claudio Frausto-Reyes

2006-01-01

317

Low temperature deposition of TiO2 thin films on polyvinyl alcohol fibers with photocatalytical and antibacterial activities  

International Nuclear Information System (INIS)

Fine particles of photoactive anatase-type TiO2 coated polyvinyl alcohol (PVA) fibers (TiO2/PVA) were prepared successfully via a simple dip-coating method. Tetrabutyl orthotitanate (TBOT) was hydrolyzed in presence of hydrolysis control agent tetrabutylammonium hydroxide (TBA)OH and the TiO2 fine particles were crystallized under microwave (MW) irradiation. The X-ray diffraction (XRD) and selected-area electron diffraction (SAED) analyses indicated that the fine particles obtained with MW irradiation have much higher crystallinity with a single phase anatase compared with the non-MW-treated solution. The continuous layers of titania were found on PVA fibers by the scanning electron microscopy (SEM) analysis. The fibers with anatase coatings showed high photocatalytic property on the photodegradation of methylene blue (MB) and high antibacterial activity

318

Li-N doped and codoped TiO2 thin films deposited by dip-coating: Characterization and photocatalytic activity under halogen lamp  

Science.gov (United States)

Li-, N-doped and codoped TiO2 powders and thin films, deposited on glass substrate using dip-coating method and Ti(OBu)4 as precursor, were prepared and their structural properties were investigated using grazing angle X-ray diffraction (GXRD), Raman spectroscopy, time resolved luminescence, X-ray photoelectron spectroscopy (XPS), ground state diffuse reflectance absorption and scanning electron microscopy (SEM). Unlike the powder samples, thin films with the same composition and calcination temperature exhibited lower crystallinity degree along with the prevalence of the anatase phase. Ground state diffuse reflectance absorption studies carried on the nanopowders have shown that both the Li and N dopants led to an increase of the band gap. XPS studies revealed differences in the binding energy of N in the presence and in the absence of Li, which was explained in terms of a modification in the chemical environment of N when Li is introduced. The photocatalytic activity of the ensuing film toward the degradation of aromatic amine pollutant revealed a huge enhancement upon doping with N or codoping with N and Li. This behavior is probably provide by a charge-transfer-complex mechanism in which neither the photocatalyst nor the organic compounds absorbs visible light by itself. The improvement in the photocatalytic properties occurred simultaneously with the increase of the lifetime of the charge carriers whenever N and Li were introduced at a level 2%.

Hamden, Z.; Boufi, S.; Conceição, D. S.; Ferraria, A. M.; do Rego, A. M. Botelho; Ferreira, D. P.; Ferreira, L. F. Vieira; Bouattour, S.

2014-09-01

319

Controlling the orientation of ZnO nanorod arrays using TiO2 thin film templates dip-coated by sol-gel  

International Nuclear Information System (INIS)

The oriented ZnO nanorod arrays have been synthesized on a silicon wafer that coated with TiO2 films by aqueous chemical method. The morphologies, phase structure and the photoluminescence (PL) properties of the as-obtained product were investigated by field-emission scanning electron microscopy (FE-SEM), X-ray diffractometer (XRD), transmission electron microscope (TEM) and PL spectrum. The nanorods were about 100 nm in diameter and more than 1 ?m in length, which possessed wurtzite structure with a c axis growth direction. The room-temperature PL measurement of the nanorod arrays showed strong ultraviolet emission. The effect of the crystal structure and the thickness of TiO2 films on the morphologies of ZnO nanostructures were investigated. It was found that the rutile TiO2 films were appropriate to the oriented growth of ZnO nanorod arrays in comparison with anatase TiO2 films. Moreover, flakelike ZnO nanostructures were obtained with increasing the thickness of anatase TiO2 films

320

Etching Characteristics and Mechanisms of TiO2 Thin Films in HBr/Cl2/Ar Inductively Coupled Plasma  

Science.gov (United States)

The TiO2 etching characteristics and mechanism in HBr/Cl2/Ar inductively coupled plasma (with a fixed bias power of 200 W) were investigated. It was found that the TiO2 etching rate in Cl2/Ar plasma is about 8 times faster than that in HBr/Ar plasma. In both HBr-rich (60% HBr + 20% Cl2 + 20% Ar) and Cl2-rich (20% HBr + 60% Cl2 + 20% Ar) plasmas, an increase in gas pressure (4-10 mTorr) results in a non-monotonic increase in TiO2 etching rate, while the variation of input power (500-800 W) causes a monotonic acceleration of the etching process. Plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling provided data on plasma parameters, steady-state densities, and fluxes of active species on the etched surface. The model-based analysis of the TiO2 etching kinetics shows a transitional regime of ion-assisted chemical reaction with domination of a chemical etching pathway.

Kim, Daehee; Efremov, Alexander; Jang, Hanbyeol; Kang, Sungchil; Yun, Sun Jin; Kwon, Kwang-Ho

2012-10-01

321

Investigation of the antibacterial effects of silver-modified TiO2 and ZnO plasmonic photocatalysts embedded in polymer thin films.  

Science.gov (United States)

Nanosilver-modified TiO2 and ZnO photocatalysts were studied against methicillin-resistant Staphylococcus aureus on the surface and against naturally occurring airborne microorganisms. The photocatalysts/polymer nanohybrid films were prepared by spray coating technique on the surface of glass plates and on the inner surface of the reactive light source. The photoreactive surfaces were activated with visible light emitting LED light at ? = 405 nm. The optical properties of the prepared photocatalyst/polymer nanohybrid films were characterized by diffuse reflectance measurements. The photocatalytic properties were verified with the degradation of ethanol by gas chromatography measurements. The destruction of the bacterial cell wall component was examined with transmission electron microscope. The antibacterial effect of the photocatalyst/polymer nanohybrid films was tested with different methods and with the associated standard ISO 27447:2009. With the photoreactive coatings, an extensive disinfectant film was developed and successfully prepared. The cell wall component of S. aureus was degraded after 1 h of illumination. The antibacterial effect of the nanohybrid films has been proven by measuring the decrease of the number of methicillin-resistant S. aureus on the surface and in the air as the function of illumination time. The photocatalyst/polymer nanohybrid films could inactivate 99.9 % of the investigated bacteria on different thin films after 2 h of illumination with visible light source. The reactive light source with the inner-coated photocatalyst could kill 96 % of naturally occurring airborne microorganisms after 48 h of visible light illumination in indoor air sample. The TEM results and the microbiological measurements were completed with toxicity tests carried out with Vibrio fischeri bioluminescence bacterium. PMID:24497305

Tallósy, Szabolcs Péter; Janovák, László; Ménesi, Judit; Nagy, Elisabeth; Juhász, Ádám; Balázs, László; Deme, István; Buzás, Norbert; Dékány, Imre

2014-10-01

322

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

323

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

International Nuclear Information System (INIS)

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

324

Structural, magnetic and optical properties of Ni-doped TiO2 thin films deposited on silicon(1 0 0) substrates by sol–gel process  

International Nuclear Information System (INIS)

Highlights: •Ni doping decreases the activation energy for the anatase-to-rutile transformation. •With increasing Ni content, the reversible ferromagnetism is found. •Sharp decrease of the EOBG at low Ni content is mainly related to phase composition. -- Abstract: Ni-doped TiO2 films were deposited on Si(1 0 0) substrates by sol–gel technique. X-ray photoelectron spectroscopy analysis suggests that the valence of Ni ion is in +2 and oxygen vacancies increase with increasing Ni content. X-ray diffraction measurements indicate that Ni doping catalyzes the anatase-to-rutile transformation (ART) of TiO2 films, which is due to the decrease of the ART activation energy. The reversible ferromagnetism of the samples with Ni fraction is found, which is due to an anatase-to-rutile junction destroying an F-center bound magnetic polaron. Optical properties of Ni-doped TiO2 films were studied by the ellipsometric spectra. With increasing Ni content, the optical band gap of TiO2 films is decreased from 3.56 to 3.34 eV, which may be related to phase composition and impurity band

325

Rapid erasing of wettability patterns based on TiO2-PDMS composite films  

International Nuclear Information System (INIS)

Research highlights: ? TiO2-PDMS composite films are prepared using the sol-gel method. ? The films show wettability conversion by irradiation with oxygen plasma. ? Hydrophobic-superhydrophilic patterns based on the TiO2-PDMS films are fabricated. ? The wettability patterns are rapidly erasable upon plasma irradiation for 1 s. - Abstract: TiO2-polydimethylsiloxane (TiO2-PDMS) composite films are prepared using the sol-gel method from a Ti(OBu)4-benzoylacetone solution containing PDMS. The prepared films are cured by irradiation with ultraviolet (UV) light. Structural changes in the films after UV irradiation are confirmed by UV-vis absorption experiments, which show that an absorption band characteristic of the benzoylacetonate chelate rings disappears. This finding is ascribed to structural changes associated with the dissociation of the chelate rings. The IR spectra of the thin films exhibit a broad absorption band after UV irradiation, indicating that a Ti-O-Ti network forms in the thin film. Contact angles are measured for the TiO2-PDMS thin films, showing wettability conversion from hydrophobic to superhydrophilic states by irradiation with oxygen plasma for 1 s. This phenomenon is explained by XPS experiments which reveal that the number of carbon atoms decreases, whereas the number of oxygen atoms increases on the surface of the TiO2-PDMS composite films. Finally, hydrophobic-ssite films. Finally, hydrophobic-superhydrophilic patterns are fabricated based on a patterned TiO2-PDMS composite film. The film displays a rapid change to superhydrophilicity over the whole film surface upon plasma irradiation for 1 s, which means that the wettability patterns are rapidly erasable.

326

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

Science.gov (United States)

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. PMID:23070060

Oum, Kawon; Lohse, Peter W; Flender, Oliver; Klein, Johannes R; Scholz, Mirko; Lenzer, Thomas; Du, Juan; Oekermann, Torsten

2012-11-28

327

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

328

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

International Nuclear Information System (INIS)

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

329

Domain epitaxy in TiO2/ -Al2O3 thin film heterostructures with Ti2O3 transient layer  

Energy Technology Data Exchange (ETDEWEB)

Rutile TiO2 films were grown epitaxially on -alumina (sapphire(0001)) substrates and characterized by x-ray diffraction and scanning transmission electron microscopy. It was revealed that the rutile film initially grows pseudomorphically on sapphire as Ti2O3 and, after a few monolayers, it grows tetragonally on the Ti2O3/sapphire platform. Formation of the Ti2O3 transient layer was attributed to the symmetry mismatch between tetragonal structure of TiO2 and hexagonal structure of alumina. The separation between the [10](101) misfit dislocations was dictated by Ti2O3 and was determined to be 9.7 which is consistent with 4/3 and 3/2 alternating domains across the film/substrate interface.

Bayati, M R [Department of Materials Science and Engineering, North Carolina State University, EB-1, Raleigh, Nor; Molaei, R [Department of Materials Science and Engineering, North Carolina State University, EB-1, Raleigh, Nor; Narayan, Jagdish [North Carolina State University; Zhou, Honghui [North Carolina State University; Pennycook, Stephen J [ORNL

2012-01-01

330

Size dependent electron transfer from CdTe quantum dots linked to TiO2 thin films in quantum dot sensitized solar cells  

International Nuclear Information System (INIS)

In this present study, we demonstrate the size dependent charge transfer from CdTe quantum dots (QDs) into TiO2 substrate and relate this charge transfer to the actual behavior of a CdTe sensitized solar cell. CdTe QDs was synthesized using mercaptopropionic acid as the capping agent. The conduction band offset for TiO2 and CdTe QDs indicates thermodynamically favorable band edge positions for smaller QDs for the electron-transfer at the QD–TiO2 interface. Time-resolved emission studies were carried out for CdTe QD on glass and CdTe QD on TiO2 substrates. Results on the quenching of QD luminescence, which relates to the transfer kinetics of electrons from the QD to the TiO2 film, showed that at the smaller QD sizes the transfer kinetics are much more rapid than at the larger sizes. I–V characteristics of quantum dot sensitized solar cells (QDSSC) with different sized QDs were also investigated indicating higher current densities at smaller QD sizes consistent with the charge transfer results. The maximum injection rate constant and photocurrent were obtained for 2.5 nm CdTe QDs. We have been able to construct a solar cell with reasonable characteristics (Voc = 0.8 V, Jsc = 1 mA cm?2, FF = 60%, ? = 0.5%). - Highlights: • Size dependant charge transfer from quantum dots to TiO2. • Smaller quantum dot sizes promote higher current densities in solar cell. • Smaller quantum dots have favorable band edge positions and transport kinetics

331

A corrosion-resistance superhydrophobic TiO2 film  

International Nuclear Information System (INIS)

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

332

Ultrathin Films of TiO2 Nanoparticles at Interfaces.  

Science.gov (United States)

The properties of a material change remarkably as a result of the scaling dimensions. The Langmuir-Blodgett (LB) film deposition technique is known to offer precise control over the film thickness and the interparticle separation. To form a well-ordered LB film, it is essential to form a stable Langmuir film at the air-water interface. Here, we report our studies on ultrathin films of TiO2 nanoparticles at air-water and air-solid interfaces. The Langmuir film of TiO2 nanoparticles at the air-water interface was found to be very stable, and it exhibits loose-packing and close-packing phases. The LB films were transferred onto solid substrates for characterization and application. The surface morphology of the LB film was obtained by a field emission scanning electron microscope. The optical and electronic properties of the LB films of TiO2 nanoparticles were studied using UV-vis spectroscopy and current-voltage measurements, respectively. The LB film of TiO2 nanoparticles was employed for ethanol gas sensing, and the sensing performance was compared to that of bulk material. Because of the enormous gain in the surface to volume ratio and the increase in crystalline defect density in the ultrathin LB film of TiO2 nanoparticles, the LB film is found to be a potential functional layer for ethanol sensing as compared to the bulk material. PMID:25557246

Choudhary, Keerti; Manjuladevi, V; Gupta, R K; Bhattacharyya, P; Hazra, A; Kumar, S

2015-02-01

333

Photocatalysis and characterization of the gel-derived TiO2 and P-TiO2 transparent thin films  

International Nuclear Information System (INIS)

The gel-derived TiO2 and P-TiO2 transparent films coated on fused-SiO2 substrates were prepared using a spin-coating technique. Effects of phosphorus dopants and calcination temperature on crystal structure, crystallite size, microstructure, light transmittance and photocatalytic activity of the films were investigated. By introducing P atoms to Ti-O framework, the growth of anatase crystallites was hindered and the crystal structure of anatase-TiO2 could withstand temperature up to 900 deg. C. The photocatalytic activities of the prepared films were characterized using the characteristic time constant (?) for the photocatalytic reaction. The titania film with a smaller ? value possesses a higher photocatalytic ability. After exposing to 365-nm UV light for 12 h, the P-TiO2 films calcined between 600 deg. C and 900 deg. C can photocatalytically decomposed ? 84 mol% of the methylene blue in water with corresponding ? ? 7.1 h, which were better than the pure TiO2 films prepared at the same calcination temperature.

334

Nanocrystalline SnO2-TiO2 thin film deposited on base of equilateral prism as an opto-electronic humidity sensor  

Science.gov (United States)

Present paper reports the synthesis of SnO2-TiO2 nanocomposite, its characterization and performance as opto-electronic humidity sensor. Nanocrystalline SnO2-TiO2 film was deposited on the base of an equilateral prism using a photo resist spinner and the as prepared film was annealed at 200 °C for 2 h. The crystal structure of the prepared film was investigated using X-ray diffraction (XRD). Minimum crystallite size of the material was found 7 nm. Surface morphology of the film was investigated by Scanning electron microscope (SEM LEO-0430, Cambridge). SEM image shows that the film is porous. Differential scanning calorimetry (DSC) of as synthesized material shows two exothermic peaks at about 40 and 110 °C, respectively which are due to the evaporation of chemical impurities and water. Further the prepared film was investigated through the exposure of humidity and relative humidity (%RH) was measured directly in terms of modulation in the intensity of light recorded on a digital power meter. The maximum sensitivity of sensor was found 4.14 ?W/%RH, which is quite significant for sensor fabrication purposes.

Yadav, B. C.; Verma, Nidhi; Singh, Satyendra

2012-09-01

335

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

OpenAIRE

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

Mohammad Hossein Habibi; Mojtaba Nasr-Esfahani

2008-01-01

336

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. (au for phenol degradation was optimized. (author)

337

TiO2 and Fe2O3 Films for Photoelectrochemical Water Splitting  

Directory of Open Access Journals (Sweden)

Full Text Available Titanium oxide (TiO2 and iron oxide (?-Fe2O3 hematite films have potential applications as photoanodes in electrochemical water splitting. In the present work TiO2 and ?-Fe2O3 thin films were prepared by two methods, e.g., sol-gel and High Power Impulse Magnetron Sputtering (HiPIMS and judged on the basis of physical properties such as crystalline structure and surface topography and functional properties such as simulated photoelectrochemical (PEC water splitting conditions. It was revealed that the HiPIMS method already provides crystalline structures of anatase TiO2 and hematite Fe2O3 during the deposition, whereas to finalize the sol-gel route the as-deposited films must always be annealed to obtain the crystalline phase. Regarding the PEC activity, both TiO2 films show similar photocurrent density, but only when illuminated by UV light. A different situation was observed for hematite films where plasmatic films showed a tenfold enhancement of the stable photocurrent density over the sol-gel hematite films for both UV and visible irradiation. The superior properties of plasmatic film could be explained by ability to address some of the hematite drawbacks by deposition of very thin films (25 nm consisting of small densely packed particles and by doping with Sn.

Josef Krysa

2015-01-01

338

The fabrication of nanocomposite thin films with TiO2 nanoparticles by the layer-by-layer deposition method for multifunctional cotton fabrics  

International Nuclear Information System (INIS)

A multilayer nanocomposite film composed of anatase TiO2 nanoparticles was fabricated on cationically modified woven cotton fabrics by the layer-by-layer molecular self-assembly technique. For cationic surface charge, cotton fabrics were pre-treated with 2,3-epoxypropyltrimethylammonium chloride (EP3MAC) by a pad-batch method. Attenuated total reflectance Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to verify the presence of deposited nanolayers. Photocatalytic activities of the nanocomposite films were evaluated through the degradation of red wine pollutant. Nano-TiO2 deposition enhanced the protection of cotton fabrics against UV radiation in comparison with the untreated cotton fabrics. Air permeability and whiteness value analysis was performed on the fabrics before and after the treatment with TiO2 nanoparticles by the layer-by-layer deposition method. Tensile strength tests of the warp and weft yarns were performed to evaluate the effect of solution pH value changes during the alternate dipping procedures. For the first time the durability of the effect of the self-assembled multilayer films on the cotton fabric functional properties was analyzed after 10 and 20 washing cycles at 40 deg. C for 30 min.

339

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

OpenAIRE

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

Yuanmin Du; Amit Kumar; Hui Pan; Kaiyang Zeng; Shijie Wang; Ping Yang; Andrew Thye Shen Wee

2013-01-01

340

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

Directory of Open Access Journals (Sweden)

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

2006-01-01

341

Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO2/ZrO2 films  

Directory of Open Access Journals (Sweden)

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

Olga Linyucheva

2006-02-01

342

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

International Nuclear Information System (INIS)

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

343

Evolution of damage fraction due to dense ionizing irradiation on TiO2 film  

International Nuclear Information System (INIS)

The evolution of damage fraction during dense ionizing irradiation at various fluences using 100 MeV Ag ion is studied. Irradiation induced modification of surface roughness and surface potential of titanium dioxide nanocrystalline thin films are estimated. TiO2 thin films deposited on Si (1 0 0) substrate were irradiated by 100 MeV Ag ion beam with varying fluences. Ion bombardment generates point and extended defects in TiO2 thin films due to dense electronic excitation. The surface morphology and surface roughness of irradiated and pristine thin films were measured using atomic force microscopy. The changes in surface potential of pristine as well as Ag ion beam irradiated thin films were measured from contact potential difference between TiO2 thin film (one electrode) of unknown work function and Au (reference electrode) of known work function using scanning Kelvin probe microscopy. The defect size and damage fraction are calculated from exponential fitting of variation of both contact surface potential difference and roughness exponent with fluence.

344

Thermal properties of TiO2 films grown by atomic layer deposition  

International Nuclear Information System (INIS)

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

345

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

International Nuclear Information System (INIS)

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

346

Thin Films  

Science.gov (United States)

Titanium dioxide (TiO2) thin films were synthesized on glass substrates by spray pyrolysis. The effect of solution flow rate on the physical properties of the films was investigated by use of x-ray diffraction (XRD), scanning electron microscopy, atomic force microscopy (AFM), and spectrophotometry techniques. XRD analysis revealed the tetragonal anatase phase of TiO2 with highly preferred (101) orientation. AFM images showed that grain size on top of TiO2 thin films depended on solution flow rate. An indirect band gap energy of 3.46 eV was determined by means of transmission and reflection measurements. The envelope method, based on the optical transmission spectrum, was used to determine film thickness and optical constants, for example real and imaginary parts of the dielectric constant, refractive index, and extinction coefficient. Ultraviolet and visible photoluminescence emission peaks were observed at room temperature. These peaks were attributed to the intrinsic emission and to the surface defect states, respectively.

Naffouti, Wafa; Nasr, Tarek Ben; Mehdi, Ahmed; Kamoun-Turki, Najoua

2014-11-01

347

Photodeposition of Prussian Blue Films on TiO(2): Additive Effect of Methanol and Influence of the TiO(2) Crystal Form.  

Science.gov (United States)

The coupling of TiO(2) and transition metal complexes is attempted with the aim of higher functionalization of the TiO(2) photocatalyst. UV irradiation (lambda(ex)>300 nm) of a TiO(2) suspension containing equimolar aqueous solutions of FeCl(3) and K(3)[Fe(CN)(6)] forms uniform thin films of "water-insoluble Prussian blue" (PB, Fe(4)(3+) [Fe(II)(CN)(6)](3)) on the surface of TiO(2) particles. The PB photodeposition is enhanced significantly by the addition of a small amount of CH(3)OH in both the rutile and anatase TiO(2) systems. The activity of anatase TiO(2) is greater than that of rutile in the presence of CH(3)OH (2.46 M) by a factor of 1.6+/-0.2, whereas the activities are comparable in the absence of CH(3)OH. These results are discussed on the basis of a proposed reaction mechanism. Copyright 2001 Academic Press. PMID:11397064

Tada, Hiroaki; Tsuji, Satoru; Ito, Seishiro

2001-07-01

348

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

OpenAIRE

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

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

2012-01-01

349

Nano-structured TiO2 film fabricated at room temperature and its acoustic properties  

International Nuclear Information System (INIS)

Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers. (fast track communication)

350

Nano-structured TiO2 film fabricated at room temperature and its acoustic properties  

OpenAIRE

Nano-structured TiO2 thin film has been successfully fabricated at room temperature. Using a quarter wavelength characterization method, we have measured the acoustic impedance of this porous film, which can be adjusted from 5.3 to 7.19 Mrayl by curing it at different temperatures. The uniform microstructure and easy fabrication at room temperature make this material an excellent candidate for matching layers of ultra-high frequency ultrasonic imaging transducers.

Zhu, Jie; Cao, Wenwu; Jiang, Bei; Zhang, D. S.; Zheng, H.; Zhou, Q.; Shung, K. K.

2008-01-01

351

Third-generation biosensors based on TiO2 nanostructured films  

International Nuclear Information System (INIS)

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

352

Density, thickness and composition measurements of TiO2 -SiO2 thin films by coupling X-ray reflectometry, ellipsometry and electron probe microanalysis-X  

International Nuclear Information System (INIS)

Mixed TiO2 -SiO2 thin films were deposited by aerosol atmospheric CVD method by using di-acetoxi di-butoxi silane (DADBS) and Ti tetra-butoxide as precursors. By varying the deposition temperatures between 470 and 600 deg. C and the ratios between the Si and Ti precursors (Si/Ti) from 2 up to 16, films with different compositions and thicknesses were deposited. The coupled analysis of the results of different characterisation methods was used in order to determine the variation of the composition, the thickness and the density of the films. First EPMA measurements were performed at different acceleration voltages with a Cameca SX50 system. By analysing, with specific software, the evolution of the intensity ratio I x/I std versus the voltage, the composition and the mass thickness (product of density by the thickness) were determined. In order to measure independently the density, X-ray reflectometry experiments were performed. By analysing the value of the critical angle and the Kiessig fringes, the density and the thickness of the layers were determined. The refractive index and the thickness of the films were also measured by ellipsometry. By assuming a linear interpolation between the index value of the pure SiO2 and TiO2 films, the film composition was deduced from the refractive index value. XPS measurements were also performed in order to obtain an independent value of the composition. A good agrndent value of the composition. A good agreement between the ways to measure the density is obtained

353

Effect of pyrolytic temperature on the properties of TiO2/ITO films for hydrogen sensing.  

Science.gov (United States)

Titanium dioxide (TiO2) thin films were prepared on ITO (222) coated glass substrates by spray pyrolysis technique. The influence of substrate temperature on the orientation, phase, vibrational bands and band gap energy of TiO2 films were discussed. The X-ray diffraction patterns of the films revealed preferentially oriented (101) TiO2 anatase phase at the substrate temperature of 300°C and 350°C. Fourier transform infrared spectra of the films showed the significant sharpening of absorption band at ?645cm(-1) with increase in substrate temperature, which clearly indicates the formation of anatase phase dependent on substrate temperature. Fourier Raman Spectra of the films showed the significant presence of long range order anatase TiO2 phase. The optical measurements of the film prepared at different substrate temperatures revealed the direct band gap of 3.15-3.63eV and indirect band gap of 3.48-3.73eV, characteristic of TiO2 anatase phase. To understand the enhancement of sensing performances of TiO2 films with substrate temperature, the gas sensing mechanism of the films towards 400sccm of hydrogen at room temperature was studied and discussed. PMID:25498820

Vijayalakshmi, K; David Jereil, S; Karthick, K

2015-03-01

354

Propriedades estruturais e eletrônicas de nanofilmes de TiO2 anatase: cálculos B3LYP-D* em sistemas periódicos bidimensionais / Stuctural and electronic properties of anatase TiO2 thin films: periodic B3LYP-D* calculations in 2D systems  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english Structural and electronic properties of titanium dioxide (TiO2) thin films, in anatase phase, were investigated using periodic 2D calculations at density functional theory (DFT) level with B3LYP hybrid functional. The Grimme dispersion correction (DFT/B3LYP-D*) was included to better reproduce struc [...] tural features. The electronic properties were discussed based on the band gap energy, and proved dependent on surface termination. Surface energies ranged from 0.80 to 2.07 J/m², with the stability orders: (101) > (100) > (112) > (110) ~ (103) > (001) >> (111), and crystal shape by Wulff construction in accordance with experimental data.

Anderson R., Albuquerque; Iêda M. G., Santos; Júlio R., Sambrano.

1318-13-01

355

Sprayed nanostructured TiO2 films for efficient photocatalytic degradation of textile azo dye.  

Science.gov (United States)

Spray pyrolysis procedure for preparation of nanostructured TiO(2) films with higher photocatalytic effectiveness and longer exploitation life is presented in this study. Thin films of active nanocrystalline TiO(2) were obtained from titanium isopropoxide, stabilized with acetyl acetone and characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The activity of sprayed nanostructured TiO(2) is tested for photocatalytic degradation of Reactive Black 5 dye with concentrations up to 80 ppm. Interesting result of the work is the reduction of toxicity after photocatalytic treatment of RB5 with TiO(2), which was confirmed by the lower percentage of mortality of Artemia salina. It was proved that the film thickness, conditions of post deposition treatment and the type of the substrate affected significantly the photocatalytic reaction. Taking into account that the parameters are interdependent, it is necessary to optimize the preparation conditions in order to synthesize photocatalytic active films. PMID:23018270

Stambolova, Irina; Shipochka, Capital Em Cyrillicaria; Blaskov, Vladimir; Loukanov, Alexandr?; Vassilev, Sasho

2012-12-01

356

Effect of Ta2O5/TiO2 thin film on mechanical properties, corrosion and cell behavior of the NiTi alloy implanted with tantalum  

International Nuclear Information System (INIS)

The NiTi shape memory alloy has been modified by plasma immersion ion implantation (PIII) with Ta at different incident currents to improve the corrosion resistance and other surface and biological properties. The surface topography, chemical components, mechanical properties, corrosion resistance and cytocompatibility are investigated. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) revealed that Ta implantation led to the formation of compact Ta2O5/TiO2 nano-film on the surface of the NiTi alloy. The results of Auger electron spectroscopy (AES) showed that Ni was suppressed in the superficial surface layer of the modified NiTi alloy samples. The results of nano-indentation illustrated a lower level of nano-hardness and Young's modulus after Ta implantation. Potentiodynamic anodic polarization curves showed that the corrosion resistance of NiTi alloys was enhanced by Ta implantation. Cells reached confluency and a double-layered structure had developed after cultured for three days. The NiTi alloy modified by a moderate incident current possesses a uniform and slippery surface morphology and the largest surface roughness, leading to the best corrosion resistance and the highest cell proliferation rate, respectively.

357

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

2013-10-01

358

Formation mechanism of noble metal nanoparticles in reactively sputtered TiO2 films  

Science.gov (United States)

Recently a simple recipe has been developed to prepare Ag nanoparticles in a TiO2 matrix {Okumu et al., [J. Appl. Phys. 97, 094305 (2005)] and Dahmen et al., [Appl. Phys. Lett. 88, 011923 (2006)]}. In this scheme, silver nanoparticles are formed in a TiO2 matrix by sputtering a thin silver film sandwiched between TiO2 layers, followed by an annealing process. To determine the formation mechanism of noble metal nanoparticles in the TiO2 matrix, we compare the behavior of Ag with two similar noble metals, gold and copper. The formation of metal nanoparticles in the TiO2 matrix is investigated using a combination of techniques including x-ray diffraction, x-ray reflectance, and optical spectroscopy. Despite the similarity of the three noble metals, no nanoparticles are formed from Cu and Au. This is in striking contrast to the behavior observed for Ag. The difference can be explained by a three step process, which involves oxidation of the metal, dissociation of the metal oxide upon annealing, and metal aggregation to form nanoparticles.

Okumu, J.; Köhl, D.; Sprafke, A.; von Plessen, G.; Wuttig, M.

2010-09-01

359

Formation mechanism of noble metal nanoparticles in reactively sputtered TiO2 films  

International Nuclear Information System (INIS)

Recently a simple recipe has been developed to prepare Ag nanoparticles in a TiO2 matrix {Okumu et al., [J. Appl. Phys. 97, 094305 (2005)] and Dahmen et al., [Appl. Phys. Lett. 88, 011923 (2006)]}. In this scheme, silver nanoparticles are formed in a TiO2 matrix by sputtering a thin silver film sandwiched between TiO2 layers, followed by an annealing process. To determine the formation mechanism of noble metal nanoparticles in the TiO2 matrix, we compare the behavior of Ag with two similar noble metals, gold and copper. The formation of metal nanoparticles in the TiO2 matrix is investigated using a combination of techniques including x-ray diffraction, x-ray reflectance, and optical spectroscopy. Despite the similarity of the three noble metals, no nanoparticles are formed from Cu and Au. This is in striking contrast to the behavior observed for Ag. The difference can be explained by a three step process, which involves oxidation of the metal, dissociation of the metal oxide upon annealing, and metal aggregation to form nanoparticles.

360

Caracterización de películas serigráficas de TiO2/alginato / Characterization of TiO2/alginate screenprinting films  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish En este trabajo se presentan los resultados de la caracterización de películas serigráficas formadas por TiO2 y alginato soportadas sobre sustratos de vidrio, aprovechando las propiedades adherentes/adsorbentes del biopolímero, con la finalidad de aplicarlas en la degradación fotocatalítica de conta [...] minantes. El análisis de este material se realizó mediante la caracterización estructural, química y óptica de películas de compositos de TiO2/alginato elaboradas en una proporción 90/10 en peso, mediante el empleo de las técnicas de perfilometría, DRX, SEM, EDS, FT-IR y UV-Vis. Se lograron películas homogéneas con un espesor controlado por el grosor de la malla serigráfica, con excelente adherencia a sustratos de vidrio y una mejor dispersión de las partículas de TiO2. Al aplicarse en la remoción de los tintes Methyl violeta 2B y Safranina O el desempeño de la película de TiO2/alginato puede ser similar al del TiO2 solo. Abstract in english In this paper we report the characterization of screen printing films formed by TiO2 and a natural polymer (alginate) supported on glass substrates; in order to take advantage of the adhesive/adsorbents biopolymer properties, achieve a better semiconductor dispersion and a better adhesion to the sub [...] strate. The analysis of this material was accomplished by structural characterization of chemical and optical films of TiO2/alginato composites prepared in a ratio 90/10 by weight, by employing techniques such as profilometry, XRD, SEM, EDS, FT-IR and UV-Vis. When applied to the removal of Methyl Violet 2B (MV-2B) and Safranin O dyes, these films exhibited the same performance as TiO2 alone.

M.A., Soto-Borbón; V.M., Sánchez-Corrales; M.E., Trujillo-Camacho.

361

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 TiO2e preparation of relatively thin TiO2 films on steel with a high photoactivity

362

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)

363

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

364

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

Science.gov (United States)

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

Du, Yuanmin; Kumar, Amit; Pan, Hui; Zeng, Kaiyang; Wang, Shijie; Yang, Ping; Wee, Andrew Thye Shen

2013-08-01

365

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

Directory of Open Access Journals (Sweden)

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

Yuanmin Du

2013-08-01

366

Microstructure of Nitrogen and Sulfur Co-doped Mesoporous TiO2 Film and its Photocatalytic Activity  

Directory of Open Access Journals (Sweden)

Full Text Available Using Ti(OBun4 as the inorganic precursor, Pluronic F127 as the templating agent, and thiourea as the additive, mesoporous anatase TiO2 thin films were prepared through sol-gel method coupled with evaporationª²induced self-assembly (EISA process. Scanning electron microscope, X-ray photoelectron spectra, N2 adsorption-desorption, X-ray diffraction, and UV-Vis spectra were used to characterize the as-synthesized mesoporous TiO2 materials. It is found that, apart from doping N, S elements into the TiO2 lattice, the mesostructure of the TiO2 thin films is changed by adding thiourea into the reactive solution. When the mole ratio of thiourea to Ti(OBun4 is 2.5%, the pore size of the synthesized mesostructured TiO2 reaches 12.4nm, and the mesoporous TiO2 sample shows the best UV photocatalytic activity in the degradation of the methyl organge (MO. When the mole ratio of thiourea to Ti(OBun4 is 5%, the absorption edge of the as-synthesized sample can be extended from 380nm to 520nm, and the sample exhibits the best visible photo catalytic activity in decomposing the Rhodamine B (RhB.

LI Hui,WANG Jin-Shu,LI Hong-Yi,YIN Shu,SATO Tsugio

2009-09-01

367

Hydrogenated TiO2 film for enhancing photovoltaic properties of solar cells and self-sensitized effect  

Science.gov (United States)

Hydrogenated TiO2 film was obtained by annealing TiO2 film at 350 °C for 2 h with hydrogen, and TiO2 films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO2 film and pristine TiO2 film. Through optical and electrochemical characterization, the hydrogenated TiO2 film showed enhanced absorption and narrowed band gap, as well as reduced TiO2 surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO2 as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO2 film, which excited electrons injecting internal conduction band of TiO2 to generate more photocurrent.

He, Hongcai; Yang, Kui; Wang, Ning; Luo, Feifei; Chen, Haijun

2013-12-01

368

Hydrogenated TiO2 film for enhancing photovoltaic properties of solar cells and self-sensitized effect  

International Nuclear Information System (INIS)

Hydrogenated TiO2 film was obtained by annealing TiO2 film at 350?°C for 2?h with hydrogen, and TiO2 films were prepared by screen printing on fluorine-doped tin oxide glass. Structural characterization by X-ray diffraction and electron microscopy did not show obvious difference between hydrogenated TiO2 film and pristine TiO2 film. Through optical and electrochemical characterization, the hydrogenated TiO2 film showed enhanced absorption and narrowed band gap, as well as reduced TiO2 surface impedance and dark current. As a result, an obviously enhanced photovoltaic effect was observed in the solar cell with hydrogenated TiO2 as photoanode without adding any dye due to the self-sensitized effect of hydrogenated TiO2 film, which excited electrons injecting internal conduction band of TiO2 to generate more photocurrent

369

TiO2 films photocatalytic activity improvements by swift heavy ions irradiation  

Science.gov (United States)

TiO2 thin films synthesized by sol-gel on glass substrates are irradiated by 90 MeV Xe ions at various fluences and room temperature under normal incidence. The structural, electrical, optical and surface topography properties before and after Xe ions irradiation are investigated. X-ray diffraction (XRD) reveals that the crystallinity is gradually destroyed, and the films become amorphous above 5×1012 ions/cm2. The band gap is not affected by Xe ions irradiation as evidenced from the optical measurements. By contrast, the conductivity increases with raising Xe fluence. The energy band diagram established from the electrochemical characterization shows the feasibility of TiO2 films for the photo-electrochemical chromate reduction. Xe ion irradiation results in enhanced photocatalytic activity in aquatic medium, evaluated by the reduction of Cr(VI) into trivalent state. TiO2 films irradiated at 1013 Xe/cm2 exhibit the highest photoactivity; 69% of chromate (10 ppm) is reduced at pH ~3 after 4 h of exposure to sunlight (1120 mW cm-2) with a quantum yield of 0.06%.

Rafik, Hazem; Mahmoud, Izerrouken; Mohamed, Trari; Abdenacer, Benyagoub

2014-08-01

370

Tailoring the wettability of nanocrystalline TiO 2 films  

Science.gov (United States)

The water contact angle (WCA) of nanocrystalline TiO 2 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

371

Tailoring the wettability of nanocrystalline TiO2 films  

International Nuclear Information System (INIS)

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.

372

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

International Nuclear Information System (INIS)

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

373

Thermo-optic properties of TiO2, Ta2O5 and Al2O3 thin films for integrated optics on silicon  

International Nuclear Information System (INIS)

The direct measurement of the thermo-optic coefficients of aluminium oxide, tantalum pentoxide and titanium dioxide thin films is presented. Using ellipsometry on monolithically integrated permutations of the layers of silicon, silicon dioxide and the material under test, allows the direct measurement of the overall thermo-optic coefficient accounting for thermally induced changes in the dielectric permittivity and density of the materials as well as the elasto-optic effect due to the non-matching thermal expansion coefficients of the different materials.

374

Photocatalytic activity of Cr-doped TiO2 nanoparticles deposited on porous multicrystalline silicon films  

Science.gov (United States)

This work deals with the deposition of Cr-doped TiO2 thin films on porous silicon (PS) prepared from electrochemical anodization of multicrystalline (mc-Si) Si wafers. The effect of Cr doping on the properties of the TiO2-Cr/PS/Si samples has been investigated by means of X-ray diffraction (XRD), atomic force microcopy (AFM), photoluminescence, lifetime, and laser beam-induced current (LBIC) measurements. The photocatalytic activity is carried out on TiO2-Cr/PS/Si samples. It was found that the TiO2-Cr/PS/mc-Si type structure degrades an organic pollutant (amido black) under ultraviolet (UV) light. A noticeable degradation of the pollutant is obtained for a Cr doping of 2 at. %. This result is discussed in light of LBIC and photoluminescence measurements. PMID:25313302

2014-01-01

375

Antibacterial effect of silver modified TiO2/PECVD films  

Science.gov (United States)

This paper deals with photocatalytic activity of silver treated TiO2 films. The TiO2 films were deposited on glass substrates by plasma enhanced chemical vapor deposition (PECVD) in a vacuum reactor with radio frequency (RF) low temperature plasma discharge in the mixture of oxygen and titanium isopropoxide vapors (TTIP). The depositions were performed under different deposition conditions. Subsequently, the surface of TiO2 films was modified by deposition of silver nanoparticles. Photocatalytic activity of both silver modified and unmodified TiO2 films was determined by decomposition of the model organic matter (acid orange 7). Selected TiO2 samples were used for tests of antibacterial activity. These tests were performed on Gram-negative bacteria Escherichia coli. The results clearly proved that presence of silver clusters resulted in enhancement of the photocatalytic activity, which was up to four times higher than that for pure TiO2 films.

Hájková, P.; Patenka, P. Å.; Krumeich, J.; Exnar, P.; Kolouch, A.; Matoušek, J.; Ko?í, P.

2009-08-01

376

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

International Nuclear Information System (INIS)

Highlights: ? TiO2-modified photoanode composed of compact underlayer and efficient electron transport network was fabricated directly by anodic electrodeposition in an aqueous TiCl3 electrolyte. ? The electrodeposited thin TiO2 layer could bridge gaps between TiO2 nanoparticles and improve the electrical contact at the FTO/TiO2 interface, leading to an efficient electron transport. ? The electrodeposited compact TiO2 layer could cover the exposed surface area of FTO to the electrolyte, which contributes to the suppression of the charge recombination. ? We demonstrated that the TiO2-modified photoanode significantly enhances the photovoltaic properties of the DSSC compared to the bare photoanode. - Abstract: Surface modification of porous TiO2 photoanode with a thin compact TiO2 layer was carried out by means of anodic electrodeposition in an aqueous TiCl3 electrolyte. Results indicated that the electrodeposited thin TiO2 layer could bridge gaps between TiO2 nanoparticles and improve the electrical contact at the FTO (fluoride-doped tin oxide)/TiO2 interface, leading to an efficient electron transport. In addition, the thin compact TiO2 layer could cover the exposed surface area of FTO to the electrolyte, which contributes to the suppression of the charge recombination. The surface treatment of mesoporous TiOurface 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.

377

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

Science.gov (United States)

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

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

2013-10-01

378

Novel Neo-Pentoxide Precursors for MOCVD Thin Films of TiO(2) and ZrO(2).[1  

Energy Technology Data Exchange (ETDEWEB)

Two novel Group IV precursors, titanium (IV) neo-pentoxide, [Ti({mu}-ONep)(ONep){sub 3}]{sub 2} (l), and zirconium (IV) neo-pentoxide, [Zr({mu}-ONep)(ONep){sub 3}]{sub 2} (2), were reported to possess relatively high volatility at low temperatures. These compounds were therefore investigated as MOCVD precursors using a lamp-heated cold-wall CVD reactor and direct sublimation without carrier gas. The ONep derivatives proved to be competitive precursors for the production of thin films of the appropriate MO{sub 2} (M = Ti or Zr) materials in comparison to other metallo-organic precursors. Compound 1 was found to sublime at 120 C with a deposition rate of {approximately}0.350 {mu}m/min onto a substrate at 330 C forming the anatase phase with < 1% residual C found in the final film. Compound 2 was found to sublime at 160 C and deposited as crystalline material at 300 C with < 1% residual C found in the final film. A comparison to standard alkoxide and {beta}-diketonates is presented where appropriate.

Boyle, Timothy J.; Francisco, Laila P.; Gallegos, Jesus J.; Rodriguez, Mark A.; Ward, Timothy L.

1999-07-14

379

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.

380

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

Scientific Electronic Library Online (English)

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

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

2011-03-01

381

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

International Nuclear Information System (INIS)

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

382

Appearance of room temperature ferromagnetism in Cu-doped TiO$_{2-\\delta}$ films  

CERN Document Server

In recent years there has been an intense search for room temperature ferromagnetism in doped dilute semiconductors, which have many potentially applications in spintronics and optoelectronics. We report here the unexpected observation of significant room temperature ferromagnetism in a semiconductor doped with nonmagnetic impurities, Cu-doped TiO$_2$ thin films grown by Pulsed Laser Deposition. The magnetic moment, calculated from the magnetization curves, resulted surprisingly large, about 1.5 $\\mu_B$ per Cu atom. A large magnetic moment was also obtained from ab initio calculations using the supercell method for TiO$_2$ with Cu impurities, but only if an oxygen vacancy in the nearest-neighbour shell of Cu was present. This result suggests that the role of oxygen vacancies is crucial for the appearance of ferromagnetism. The calculations also predict that Cu doping favours the formation of oxygen vacancies.

Duhalde, S; Chiliotte, C; Torres, C E R; Errico, L A; Cabrera, A F; Renteria, M; Sánchez, F; Weissmann, M

2005-01-01

383

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

384

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.

385

Laser-induced electron transfer desorption/ionization of metal complexes on TiO2 films  

Science.gov (United States)

Thin titanium dioxide (TiO2) films were studied as ion emitters for the laser-induced electron transfer desorption/ionization (LETDI) of metal complexes with organic reagents. The TiO2 films (350 nm thick) were deposited on the silicon substrates by e-beam evaporation of TiO2 powder. Copper complex with phthalocyanine, rhenium complex with thiocarbanilide and platinum complex with 8-quinolinethiol were studied as the test analytes. Reflectron time-of- flight mass spectrometer with the rotating ball interface was used for analysis. The analytes were applied on the surface of TiO2 film using an electrospray deposition. All tested compounds are detected as the radical molecular ions with no fragmentation. It is found, that TiO2 films are very stable and show good sensitivity in examined range of the analyte concentrations. The limits of detection of studied complexes were at the subfemtomole range, and the relative standard deviation was less than 10%.

Grechnikov, A. A.; Georgieva, V.; Borodkov, A. S.; Nikiforov, S. M.; Raicheva, Z.; Lazarov, J.; Donkov, N.

2014-12-01

386

Investigation into the photo-induced change in wettability of hydrophobized TiO 2 films  

Science.gov (United States)

The photo-induced change in wettability of hydrophobized TiO 2 films has been investigated for steel coated with acidic TiO 2 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). TiO 2 films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 160°. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 0°. 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 °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 °C for 10 min) allow the preparation of relatively thin TiO 2 films on steel with a high photoactivity.

Risse, Gunter; Matys, Sabine; Böttcher, Horst

2008-07-01

387

Photo-induced wettability of TiO2 film with Au buffer layer  

International Nuclear Information System (INIS)

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

388

Characteristics and anticorrosion performance of Fe-doped TiO2 films by liquid phase deposition method  

Science.gov (United States)

Fe-doped TiO2 thin films were fabricated by liquid phase deposition (LPD) method, using Fe(III) nitrate as both Fe element source and fluoride scavenger instead of commonly-used boric acid (H3BO3). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectrum were employed to examine the effects of Fe element on morphology, structure and optical characteristics of TiO2 films. The as-prepared films were served as photoanode applied to photogenerated cathodic protection of SUS304 stainless steel (304SS). It was observed that the photoelectrochemical properties of the as-prepared films were enhanced with the addition of Fe element compared to the undoped TiO2 film. The highest photoactivity was achieved for Ti13Fe (Fe/Ti = 3 molar ratio) film prepared in precursor bath containing 0.02 M TiF4 + 0.06 M Fe(NO3)3 under white-light illumination. The effective anticorrosion behaviors can be attributed to the Fe element incorporation which decreases the probability of photogenerated charge-carrier recombination and extends the light response range of Fe-doped TiO2 films appeared to visible-light region.

Liu, Yu; Xu, Chao; Feng, ZuDe

2014-09-01

389

Low temperature preparation of TiO2 nanodot film on substrates  

International Nuclear Information System (INIS)

Herein, we report a photoinduced transition of hydrophobicity to high hydrophilicity of TiO2 nanodot films in applications of cell sheet engineering. A phase-separation-induced self-assembly process was adopted to prepare a TiO2 nanodot gel film on a substrate. Subsequently, a hydrothermal treatment (with ethanol/water at 140 deg. C for 2 h) was used to convert the nanodot gel film to TiO2 nanodot solid film. The resulting TiO2 dots were amorphous with adjustable size and density. The amorphous TiO2 nanodot film showed a conversion from a good hydrophobic surface, with a water contact angle (WCA) of 67.6 ± 2.0 deg., to a highly hydrophilic one, with a WCA of 5.3 ± 2.0 deg. (i.e. almost superhydrophilic) after UV irradiation. A good reversibility was also observed.

390

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

OpenAIRE

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 a...

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

2009-01-01

391

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.

Mohammad Hossein Habibi

2008-04-01

392

Site selective micro-patterned rutile TiO2 film through a seed layer deposition.  

Science.gov (United States)

Micro-patterned films obtained from micro-contact printing (microCP) method are often challenged by site selectivity limitation. For applications site-selectivity requires improvements. In this paper a site-selective deposition of the rutile TiO2 thin films on patterned SnO2 film, which was formed on the patterned octadecyltrichlorosilane (OTS) SAMs through microCP is described. The depositions proceeded in an environmentally friendly aqueous solution (SnCl4 and peroxotitanium acidic solution) at a lower temperature (80 degrees C). It is shown that the OTS SAMs has a good selectivity deposition for SnO2 particles, which was mainly dominated by the heterogeneous nucleation mechanism. The SnO2 layer had a structure-directing effect for growth of the rutile TiO2, which was usually formed above 600 degrees C. The patterned films were characterized by a variety of techniques, including ellipsometry, optical microscopy, SEM, AFM, XPS, and DLS to determine the thicknesses, topologies, microstructures, chemical compositions of the films, particle sizes and zeta potentials of the titanium particles. PMID:17391689

Liang, Shan; Chen, Miao; Xue, Qunji; Qi, Youli; Chen, Jianmin

2007-07-01

393

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

2007-03-01

394

Antimicrobial and Barrier Properties of Bovine Gelatin Films Reinforced by Nano TiO2  

Directory of Open Access Journals (Sweden)

Full Text Available The effects of nano titanium dioxide incorporation were investigated on the water vaporpermeability, oxygen permeability, and antimicrobial properties of bovine gelatin films. The nano TiO2 (TiO2-N was homogenized by sonication and incorporated into bovine gelatin solutions at different concentrations(e.g. 1, 2, 3, and 5% w/w of dried gelatin. The permeability of the films to water vapor and oxygen wassignificantly decreased by incorporating of low concentration TiO2-N to gelatin solutions. TiO2-N gelatin filmsshowed an excellent antimicrobial activity against Staphylococcus aureus and Escherichia coli. Theseproperties suggest that TiO2-N has the potential as filler in gelatin-based films for using as an active packagingmaterials in pharmaceutical and food packaging industries.

R. Nassiri

2013-11-01

395

Hydrothermal growth of rutile TiO2 nanorod films on titanium substrates  

International Nuclear Information System (INIS)

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

396

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...

397

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

2009-01-01

398

Chemical composition of electron-beam evaporated TiO2 films  

OpenAIRE

Chemical composition and optical properties of TiO2 films depend on deposition conditions. A detailed investigation has been made on the influence of deposition parameters, such as starting material, substrate temperature, and post deposition heating in air on the chemical composition of TiO2 films deposited by electron-beam evaporation of TiO and TiO2 in neutral and ionized oxygen. The chemical composition of the films has been analyzed by x-ray photoelectron spectroscopy and Auger electron ...

Rao, Narasimha K.; Mohan, S.; Hegde, Ms; Balasubramanian, Tv

1993-01-01

399

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

400

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

2012-06-01

401

Nucleation dynamics of nanostructural TiO2 films with controllable phases on (001) LaAlO3.  

Science.gov (United States)

Microstructure evolution and nucleation dynamics of TiO2 nanostructural thin films on (001) LaAlO3 substrates grown by the polymer-assisted deposition technique have been systematically studied with the increase of annealing temperature. Epitaxial anatase TiO2 phase with nanometer-scaled periodic surface strip patterns can be achieved when the sample is annealed at 900 ° C. It is also found that the morphology of the surface pattern is related to the ramping rate of the temperature during annealing. The formation of the surface strip pattern can be considered to be associated with the diffusion limit growth dynamics. The surface pattern structure was found to strongly affect the hydrophilic properties of the thin films. PMID:24334681

Lin, Yuan; Zeng, Bo; Ji, Yanda; Liang, Weizheng; Feng, Dayu; Gao, Min; Zhang, Yin; Chen, Xinxin; Chen, Bin; Chen, Chonglin

2014-01-10

402

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

Sigrid Bernstorff

2010-11-01

403

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

Science.gov (United States)

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

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

2013-05-01

404

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

OpenAIRE

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 trans...

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

2010-01-01

405

Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol–gel TiO2 films  

International Nuclear Information System (INIS)

TiO2 thin films grown on different kinds of substrates were obtained by sol–gel process. X-ray diffraction revealed that the TiO2 lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV–Vis absorbance spectra exhibited a red-shift of the absorbance edge of the TiO2 films suggesting a lowering of the band gap, which is a direct consequence of the increase of the compressive stress. X-ray photoelectron spectroscopy revealed that the surface composition of titania films was similar except for sodium-ion concentration. The rate observed during the photo-oxydation of the stearic acid on TiO2/QS was twice as high as that of TiO2/BSG and about 1000 times superior to that of TiO2/SLG. The photoinduced wettability shows an identical dependence of the compressive stress. According to these results, the compressive stress could be used to tune the band gap of the titanium oxide in order to enhance the photoinduced properties.

406

Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol-gel TiO2 films  

OpenAIRE

TiO2 thin films grown on different kinds of substrates were obtained by sol–gel process. X-ray diffraction revealed that the TiO2 lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV–Vis absorbance spect...

Ghazzal, Mohamed N.; Chaoui, N.; Genet, Michel; Gaigneaux, Eric M.; Robert, D.

2011-01-01

407

Enhanced photoelectrocatalytic degradation of phenols with bifunctionalized dye-sensitized TiO2 film  

International Nuclear Information System (INIS)

Highlights: ? Bifunctionalized TiO2 film with a dye-sensitized region and a degradation region. ? Electrons and positive charges induced by visible light participate in degradation. ? The degradation efficiency is enhanced remarkably by external potential. ? 99% removal of 4-chlorophenol was achieved by this device after 2 h. - Abstract: A degradation device containing a bifunctionalized TiO2 film electrode and an anode electrode was described. The bifunctionalized TiO2 film electrode is composite of an area of dye-sensitized TiO2 film, electrolyte and counter electrode, which is similar to the structure of dye-sensitized solar cells (DSSCs). Electrons and positive charges induced by visible light absorption of dyes could arrive at the degradation region of the bifunctionalized TiO2 film electrode and the anode electrode, respectively. Both could produce hydroxyl radicals (·OH) to participate in the degradation reaction. The degradation efficiency was enhanced remarkably by an external potential. Meanwhile, the effects of dye-sensitized TiO2 film area and pH value on the degradation of 4-chlorophenol (4-CP) were tested. An insight into degradation pathway, plausible mechanism for 4-CP and degradation of other phenols were also discussed here.

408

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.

2009-03-01

409

Fine control of the amount of preferential orientation in DC magnetron sputtered nanocrystalline TiO2 films  

Science.gov (United States)

Different crystal facets of anatase TiO2 are known to have different chemical reactivity; in particular the {001} facets which truncates the bi-tetrahedral anatase morphology are reported to be more reactive than the usually dominant {101} facets. Anatase TiO2 thin films were deposited by reactive DC magnetron sputtering in Ar/O2 atmosphere and were characterized using Rietveld refined grazing incidence X-ray diffraction, atomic force microscopy and UV/Vis spectroscopy. By varying the partial O2 pressure in the deposition chamber, the degree of orientation of the grains in the film could be systematically varied with preferred orientation changing from random upto 39% as determined by March-Dollase method. The orientation of the films is shown to correlate with their reactivity, as measured by photo-degradation of methylene blue in water solutions. The results have implications for fabrication of purposefully chemically reactive thin TiO2 films prepared by sputtering methods.

Stefanov, B.; Granqvist, C. G.; Österlund, L.

2014-11-01

410

The effect of full/partial UV-irradiation of TiO2 films on altering the behavior of fibrinogen and platelets.  

Science.gov (United States)

Titanium oxide (TiO2) thin film is a potential candidate for the surface modification of blood-contacting devices. It has previously been reported that ultraviolet light (UV) irradiation could alter the biocompatibility of TiO2 films. However, the effect of UV-irradiated TiO2 films on blood compatibility has rarely been reported. This study attempts to determine: (1) whether UV-irradiation of TiO2 films enhances their blood compatibility, (2) the interaction between UV-irradiated TiO2 films, fibrinogen (Fgn), and platelets, especially how Fgn and platelets respond to the geometry of the partially UV-irradiated TiO2 film surface. Anatase TiO2 films were subjected to full and partial UV-irradiation. Full UV-irradiation improved the blood compatibility of TiO2 films by almost completely inhibiting the adhesion and activation of platelets, strongly suppressing the adsorption and conformational change of Fgn, and preventing the formation of fibrin fibers. Additionally, hemolysis was not observed. After partial UV-irradiation, the regions where Fgn adsorption was reduced (Fgn-dark regions) were formed at regions where UV-irradiation had occurred, but were extended in comparison with the UV-irradiated regions, which could be related to the generation and diffusion of reactive oxygen species (ROS) on the UV-irradiated TiO2 surface. It is worthwhile to study how ROS altered the nature of TiO2 films, thereby enhancing their blood compatibility. Furthermore, platelets were found adhering to the Fgn-adsorbed regions (Fgn-bright regions) selectively, suggesting that the inhibition of platelet adhesion could be related to the suppression of Fgn adsorption on the UV-irradiated TiO2 surface. It was also noted that platelet surface coverage (Sp) was not linearly correlated with Fgn-bright region surface coverage (Sf), which indicated that the adhesion and spreading of platelets were regulated by both Sf and the geometry of Fgn. PMID:25172575

Chen, Jiang; Zhao, Ansha; Chen, Huiqing; Liao, Yuzhen; Yang, Ping; Sun, Hong; Huang, Nan

2014-10-01

411

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

International Nuclear Information System (INIS)

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.

412

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

413

Optimization of the structure nanoporous TiO2 film in a dye- sensitized solar cell  

Science.gov (United States)

The numerical model of dye-sensitized solar cell based on TiO2 presented here allow to construct the theoretical I-V characteristics, determine the photovoltaic parameters and obtain important information about the main factors that influence DSSC performance. For modeling of solar cell was considered system of one-dimensional differential continuity equations, describing the charge transfer in its structure. The simulated results allow to determine the optimal TiO2 particle diameter (radius), thickness, porosity and topological dimensions TiO2 film.

Malyukov, S. P.; Kulikova, I. V.; Sayenko, A. V.; Klunnikova, Yu V.

2014-10-01

414

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

415

Anatase TiO2 sols derived from peroxotitanium acid and to form transparent TiO2 compact film for dye-sensitized solar cells  

International Nuclear Information System (INIS)

Graphical abstract: Dye-sensitized solar cells with TiO2 nanocrystalline porous film in absence of compact film (A) and in presence of compact film in thickness of 1.0 ?m (B), 2.5 ?m (C), 4.0 ?m (D), respectively. Highlights: ? Anatase TiO2 sols were prepared by the hydrothermal treatment of peroxotitanium acid. ? TiO2 sols were used for DSSC photoelectrode as the compact film on FTO layer. ? The transmittance of the TiO2 compact film on FTO reached 80%. ? The ? of DSSCs in the presence of the compact film has improved significantly from 4.2% to 5.6%. - Abstract: Transparent and surfactant-free TiO2 sols containing anatase nanocrystals were prepared by the hydrothermal treatment of water-soluble peroxotitanium acid (PTA) at a temperature of 120 deg. C. The TiO2 nanocrystals were characterized by transmission electron microscopy (TEM). The TEM results indicated that the TiO2 nanocrystals were nanorod-like with diameters of less than 7 nm after the subsequently hydrothermal treatment. A gradient layer between the transparent fluorine doped SnO2 (FTO) layer and the porous titanium dioxide nanocrystalline film for dye-sensitized solar cells (DSSCs) photoelectrodes, was made with the as-prepared TiO2 sols. The TiO2 gradient layers were characterized by field-emission scanning electron microscopy and UV-vis absorption spectrometry. After the gradient layometry. After the gradient layer deposition on the FTO coated glass, the composite multilayer film exhibited the visible light transmittance of 80% which approached to that of bare FTO glass. The photo-to-electric energy conversion efficiency of the N719 dye-sensitized solar cell had significantly improved from 4.2% to 5.6% in the presence of the compact layer between FTO and the porous TiO2 nanocrystalline film under of AM1.5 illumination (100 mW/cm2). The remarkable improvements in short-circuit current for the DSSCs was due to the effective gradient layer at the FTO-TiO2 interface which prevented direct contact of electrolytes with FTO and consequently reduced charge recombination losses.

416

The properties of TiO2 nanoceramic films prepared by electron beam evaporation.  

Science.gov (United States)

TiO2 nanoceramic films were deposited on polycarbonate (PC) substrate by electron beam evaporation. This deposition technique is well established for producing dense and adhesive optical films. At high power, the particles arrived at the substrate with high kinetic energy, and high impact also led to low density due to porous structure. The porous TiO2 films resulted in low linear refractive index. As the film thickness increased, the surface of TiO2 films exhibited the grain growth obviously, resulting in high surface roughness. The transparent TiO2 films showed red-shift because of large grain size. Transparent materials generally have optical Kerr effect. The knowledge of nonlinear refractive index of materials is of great interest due to its potential applications in designing optical devices. Moiré deflectometry is a powerful tool for measuring nonlinear refractive index of materials. In this study, this method is applied for measuring the nonlinear refractive index of TiO2 nanoceramic films on PC substrates. The nonlinear refraction index can be measured to be in order of 10(-8) cm2 W(-1) and the change in refractive index is in order of 10(-5). PMID:19504888

Lin, Su-Shia; Hung, Yuan-Hsun; Chen, Shin-Chi

2009-06-01

417

The effect of multiwalled carbon nanotube doping on the CO gas sensitivity of TiO2 xerogel composite film  

Science.gov (United States)

A simple sol-gel method was applied for the synthesis of 0.01 wt% multiwalled carbon nanotubes (MWCNTs)-doped TiO2 xerogel composite film. The film's CO gas sensing properties were then evaluated. Doped MWCNTs were coated with TiO2 and distributed on a TiO2 xerogel matrix. The TiO2 xerogel showed an anatase structure after heat treatment at 450 °C under vacuum. The specific surface area of the composite material was larger than the pure TiO2 xerogel material. The CO gas sensitivity of the MWCNTs(0.01 wt%)-doped TiO2 xerogel composite film was found to be seven times higher than that of pure TiO2 xerogel film and to have good stability. This higher gas-sensing property of the composite film was due to both an increase of specific surface area and the n-p junction structure of the TiO2 xerogel coated on MWCNTs. The electrons generated from TiO2 after adsorption of CO gas induces electron transfer from the TiO2 to the MWCNTs. This induces a characteristic change in the MWCNTs from p-type to n-type, and the resistance of MWCNTs-doped TiO2 xerogel composite sensor is therefore decreased.

Lee, Jin-Seok; Ha, Tae-Jung; Hong, Min-Hee; Park, Chang-Sun; Park, Hyung-Ho

2013-03-01

418

Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2  

International Nuclear Information System (INIS)

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

419

Charge separation and charge transport in nanostructured TiO2 film electrodes  

Science.gov (United States)

Photoelectrochemical measurements have been performed on film electrodes consisting of linked nano-sized TiO2 colloids. The film thickness ranged from 1 - 40 micrometers. The film network was attached to a thin transparent conducting layer of SnO2 allowing for photogenerated electrons to be collected in an outer electrical circuit. By illuminating electrodes of different thicknesses with monochromatic light from either side, it was possible to induce charge separation in different regions of the film network. In this way, it was proved that electrons have different probabilities of reaching the back contact depending on the location in the film where they are created. The results also illustrate the importance of the redox species in the cavities of these porous electrodes. By adding acceptors to the electrolyte it was possible to alter the conditions for charge transfer in the nanocrystalline film. It was shown that electron acceptors such as oxygen or iodine in the solution strongly affects the rate of charge transfer at the particle-electrolyte interface and the transport of electrons throughout the TiO2 film-network. Modification of the semiconductor-electrolyte interface with surface adsorbed pyridine induced major changes in the charge transfer events at the interface. The photocurrent yields were greatly improved by this surface treatment. The effect of pH in solution was also investigated. The rate of charge transfer at the particle-electrolyte interface was changed at high surface density of OH--ions. This was explained due to the change of the surface energy causing different driving forces for redox reactions, but also due to the more negatively electrostatic surface potential of the particles preventing the encounter of negatively charged redox species with the colloid surface. Phototransient measurements indicated a depletion of redox species in the pores of the film. Thereby it was pointed out that the dynamics of the redox species in the confined cavities of the film are a limiting factor for the charge separation efficiency in nanocrystalline film. The photovoltage in anaerobic solutions sustained for very long periods, indicating that the linked particles may work as reservoirs for photoexcited electrons if the access to electron acceptors in the solution is choked. It was concluded that surface processes are favored at the small semiconductor particles used in this study.

Lindstrom, Henrik; Hagfeldt, Anders; Rensmo, Hakan; Solbrand, Anita; Sodergren, Sven; Lindquist, Sten-Eric

1995-08-01