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Sample records for tio2 thin films

  1. Comparison of the phase transformation rate for TiO2 thin film and TiO2 nanorods

    Science.gov (United States)

    Chen, Yi; Kang, K. S.; Nayak, J.; Kim, J.

    2010-04-01

    Relative phase transformation rates are compared with TiO2 sol-gel thin film and TiO2 nanorods. TiO2 thin film was prepared with sol-gel process using titaanium isoproxide (TIP) as a precusor, ethanol as a solvent and HCl as a catalyst. The TiO2 nanorods were synthesized with low temperature proccess (100 °C) using TIP, oleic acid, and aqueous trimethylamine. The prepared thin film and nanorods were annealed at 850 °C for 3 h. X-ray diffraction patterns reveal that the TiO2 thin film and TiO2 nanorods have amorphase phase and anatase phase, respectively before annealing process. Approximately 60 and 3 % of TiO2 thin film and TiO2 nanorods transformed from anatase phase to rutile phase after annealing at 850 °C for 3 h. Relatively small amount of TiO2 nanorods transformed to rutile phase compared with TiO2 thin film. This small amount of phase transformation may be due to the small diameter of the TiO2 nanorods, which have thermodynamecally favorable anatase phase.

  2. Mesoporous TiO2 thin films for photovoltaic applications

    OpenAIRE

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

    2008-01-01

    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...

  3. Phase transformation comparison of TiO2 nanorods and TiO2 thin film after annealing

    Science.gov (United States)

    Chen, Yi; Yang, Sang Yeol; Kim, Jaehwan

    2012-06-01

    This paper reports the degree of phase transformation of titanium dioxide (TiO2) thin film and TiO2 nanorods before and after annealing. TiO2 nanorods were synthesized with titanium isoproxide (TIP) in Oleic acid, having approximately 5 nm diameter and 30 nm length. TiO2 thin film was fabricated by sol-gel method using TIP, ethanol and hydrochloric acid. The characteristics of TiO2 nanorods and thin film were investigated with transmission electron microscope, atomic force microscope and x-ray diffraction patterns. Although the TiO2 thin film shows no crystallite peak, as-synthesized TiO2 nanorods show broad anatase phase diffraction peaks. After annealing the TiO2 nanorods at 850°C for 3 h, only approximately 3.1% of crystallite phase was transformed from anatase phase to rutile phase. This slow phase transformation might be due to the small diameter of the nanorods, which is thermodynamically more stable than the anatase crystallite phase. However, although the film has small grains on the surface, approximately 59.5% of phase was transformed from anatase to rutile crystallite structure after the thin film annealing. This large amount of phase transformation might be due to the two dimensional structure of the thin film.

  4. 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. Preparation and Evaluation of TiO2 Nanoparticle Thin Films using Electrophoresis Deposition Method

    International Nuclear Information System (INIS)

    Thin films of synthesized TiO2 nanoparticles were deposited by constant-current electrophoresis deposition in ethanol using colloid of various concentration of TiO2 nanoparticles. Thin films deposited in colloid of high concentration had the high density, no apparent cracks and the higher optical transparency. The eficiency of the fabricated dye-sensitized solar cells was improved using thin film of TiO2 nanoparticle deposited in colloid with high concentration. It was suggested that the thin film with high quality could be deposited by making the velocity of a TiO2 nanoparticle low because the linkage between TiO2 nanoparticles were promoted by oriented attachment mechanism.

  6. Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping

    OpenAIRE

    Zhifeng Liu, Yun Wang

    2012-01-01

    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...

  7. PHOTOCATALYTIC PROPERTIES OF Cr DOPED TiO2–SiO2 NANOSTRUCTURE THIN FILM

    Directory of Open Access Journals (Sweden)

    Akbar Eshaghi

    2012-07-01

    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.

  8. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film

    Science.gov (United States)

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I.; Qamaruddin, Muhammad; Yamani, Zain H.

    2015-02-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested.

  9. The structural and electrical properties of thermally grown TiO2 thin films

    International Nuclear Information System (INIS)

    We studied the structural and electrical properties of TiO2 thin films grown by thermal oxidation of e-beam evaporated Ti layers on Si substrates. Time of flight secondary ion mass spectroscopy (TOF-SIMS) was used to analyse the interfacial and chemical composition of the TiO2 thin films. Metal oxide semiconductor (MOS) capacitors with Pt or Al as the top electrode were fabricated to analyse electrical properties of the TiO2 thin films. We show that the reactivity of the Al top contact affects electrical properties of the oxide layers. The current transport mechanism in the TiO2 thin films is shown to be Poole-Frenkel (P-F) emission at room temperature. At 84 K, Fowler-Nordheim (F-N) tunnelling and trap-assisted tunnelling are observed. By comparing the electrical characteristics of thermally grown TiO2 thin films with the properties of those grown by other techniques reported in the literature, we suggest that, irrespective of the deposition technique, annealing of as-deposited TiO2 in O2 is a similar process to thermal oxidation of Ti thin films

  10. 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

  11. Temperature dependence of gas sensing behaviour of TiO2 doped PANI composite thin films

    International Nuclear Information System (INIS)

    In the present work we have reported the effect of temperature on the gas sensing properties of TiO2 doped PANI composite thin film based chemiresistor type gas sensors for hydrogen gas sensing application. PANI and TiO2 doped PANI composite were synthesized by in situ chemical oxidative polymerization of aniline at low temperature. The electrical properties of these composite thin films were characterized by I-V measurements as function of temperature. The I-V measurement revealed that conductivity of composite thin films increased as the temperature increased. The changes in resistance of the composite thin film sensor were utilized for detection of hydrogen gas. It was observed that at room temperature TiO2 doped PANI composite sensor shows higher response value and showed unstable behavior as the temperature increased. The surface morphology of these composite thin films has also been characterized by scanning electron microscopy (SEM) measurement

  12. Sub-band-gap photoresponse of TiO2-x thin-film-electrolyte interface

    Science.gov (United States)

    Kim, Wha-Tek; Kim, Chang-Dae; Choi, Q. Won

    1984-10-01

    When a TiO2-x thin-film-electrolyte interface is illuminated by the monochromatic light in the sub-band-gap region, broad photocurrent peaks are observed at 462, 515, 1050, and 1258 nm. The energies of these peaks are in good agreement with the energies of defect levels of the TiO2 single crystal due to oxygen vacancies. From these experimental results, the photoresponse of the TiO2-x thin-film-electrolyte interface in the sub-band-gap region is interpreted as arising from electronic excitations between the trap levels which originate from the defects of the TiO2-x thin film and the conduction band.

  13. Micropatterning of TiO2 Thin Films by MOCVD and Study of Their Growth Tendency.

    Science.gov (United States)

    Hwang, Ki-Hwan; Kang, Byung-Chang; Jung, Duk Young; Kim, Youn Jea; Boo, Jin-Hyo

    2015-01-01

    In this work, we studied the growth tendency of TiO2 thin films deposited on a narrow-stripe area (thin films were selectively deposited on OTS patterned Si(100) substrates by MOCVD. The experimental data showed that the film growth tendency was divided into two behaviors above and below a line patterning width of 4??m. The relationship between the film thickness and the deposited area was obtained as a function of f(x) = a[1 - e((-bx))]c. To find the tendency of the deposition rate of the TiO2 thin films onto the various linewidth areas, the relationship between the thickness of the TiO2 thin film and deposited linewidth was also studied. The thickness of the deposited TiO2 films was measured from the alpha-step profile analyses and cross-sectional SEM images. At the same time, a computer simulation was carried out to reveal the relationship between the TiO2 film thickness and deposited line width. The theoretical results suggest that the mass (velocity) flux in flow direction is directly affected to the film thickness. PMID:25799219

  14. Superhydrophilic graphene-loaded TiO2 thin film for self-cleaning applications.

    Science.gov (United States)

    Anandan, Srinivasan; Rao, Tata Narasinga; Sathish, Marappan; Rangappa, Dinesh; Honma, Itaru; Miyauchi, Masahiro

    2013-01-01

    We develop a simple approach to fabricate graphene-loaded TiO(2) thin films on glass substrates by the spin-coating technique. Our graphene-loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene-loaded TiO(2) thin film also contributes to the self-cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene-loaded TiO(2) films may have the potential use in various indoor applications. PMID:23240759

  15. Development of multilayered nanocrystalline TiO2 thin films for photovoltaic application

    Science.gov (United States)

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

    2014-04-01

    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%.

  16. SILAR deposited TiO2 thin film for supercapacitor application

    Science.gov (United States)

    Deshmukh, P. R.; Lokhande, C. D.

    2013-06-01

    The paper presents the synthesis and characterization of Titanium dioxide (TiO2) thin films prepared by the simple and low cost successive ionic layer adsorption and reaction (SILAR) method. The TiO2 thin films are characterized by scanning electron microscopy (SEM), FT-IR, FT-Raman and UV-VIS spectroscopy techniques. The SEM study of TiO2 shows the cracked morphology on the substrate surface. The characteristic peaks of TiO2 are observed in the FT-IR and FT-Raman studies. The optical study shows band gap of 3.3 eV. The cyclic voltammetry study shows the specific capacitance of 16 F.g-1.

  17. 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)

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

    Science.gov (United States)

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

    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.

  19. Preparation and Photocatalytic Activity of TiO2 Thin Films on Al Alloys

    Directory of Open Access Journals (Sweden)

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

    2012-06-01

    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.

  20. 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.

  1. 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

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

    CERN Document Server

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

    2007-01-01

    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.

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

    International Nuclear Information System (INIS)

    In this work, we present an X-ray absorption spectroscopy (XAS) characterization of the local environment of the impurity in room temperature ferromagnetic (RTF) anatase TiO2 thin films doped with Co, Ni, Cu, or Zn, deposited on LaAlO3 substrate by pulsed laser deposition (PLD). 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 RT ferromagnetism of the samples could be assigned to the metal transition atoms replacing Ti in TiO2 anatase

  4. Visible-light photocatalytic activity of nitrided TiO2 thin films

    International Nuclear Information System (INIS)

    TiO2 thin films have been applied in UV-light photocatalysis. Nevertheless visible-light photocatalytic activity would make this material more attractive for applications. In this work we present results on the modification of titanium oxide (anatase) sol-gel thin films, via a nitriding process using a microwave plasma source. After the treatment in the nitrogen plasma, the nitrogen content in the TiO2 films varied in the range from 14 up to 28 at%. The titanium oxide films and the nitrided ones were characterized by XPS, micro-Raman spectroscopy and UV-vis spectroscopy. Photocatalytic activity tests were done using a Methylene Blue dye solution, and as catalyst TiO2 and nitrided TiO2 films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO2 films had photocatalytic activity, while the unnitrided films did not.

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

    Science.gov (United States)

    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

    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

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

    Science.gov (United States)

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

    2008-03-01

    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

  7. Visible light catalysis of rhodamine B using nanostructured Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films.

    Science.gov (United States)

    Mahadik, M A; Shinde, S S; Mohite, V S; Kumbhar, S S; Moholkar, A V; Rajpure, K Y; Ganesan, V; Nayak, J; Barman, S R; Bhosale, C H

    2014-04-01

    The Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) composite films are deposited using spray pyrolysis method onto glass and FTO coated substrates. The structural, morphological, optical and photocatalytic properties of Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films are studied. XRD analysis confirms that films are polycrystalline with rhombohedral and tetragonal crystal structures for Fe2O3 and TiO(2) respectively. The photocatalytic activity was tested for the degradation of Rhrodamine B (Rh B) in aqueous medium. The rate constant (-k) was evaluated as a function of the initial concentration of species. Substantial reduction in concentrations of organic species was observed from COD and TOC analysis. Photocatalytic degradation effect is relatively higher in case of the TiO(2)/Fe(2)O(3) than TiO(2) and Fe(2)O(3) thin film photoelectrodes in the degradation of Rh B and 98% removal efficiency of Rh B is obtained after 20min. The photocatalytic experimental results indicate that TiO(2)/?-Fe(2)O(3) photoelectrode is promising material for removing of water pollutants. PMID:24721593

  8. Synthesis of Structured Macroporous TiO2 Thin Films and Investigation on Their Photocatalytic Activities

    International Nuclear Information System (INIS)

    Synthesis of structured macroporous TiO2 thin films on quartz substrate (macro-TiO2/Q) was performed by a dip-coating method using poly(methyl methacrylate) (PMMA) microspheres as template. Obtained TiO2 thin films kept high transparency and had anatase crystalline structure. SEM observations revealed that the macropores were uniformly formed on the film surface. The size of macropores was quite similar to the diameter of PMMA microspheres as template. In comparison to the nonporous TiO2 thin films (TiO2/Q), macro-TiO2/Q exhibited twice higher photocatalytic activity for decolorization of methylene blue in water. Decomposition of acetaldehyde in gas phase also proceeded efficiently on macro-TiO2/Q. Moreover, the surface of macro-TiO2/Q was easily hydrophilized after a short period of UV light irradiation and maintained lower water contact angle in the dark for a long period as compared to those of TiO2/Q.

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

    Science.gov (United States)

    Lu, Liu; Xia, Xiaohong; Luo, J. K.; Shao, G.

    2012-12-01

    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 [1?0?1] texture. Mn incorporation stabilized the rutile phase and induced lattice contraction in the [1?0?0] direction. The texture in the Mn-doped films changed from [1?1?0] to [2?0?0] 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.

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

    International Nuclear Information System (INIS)

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

  11. Distributed Bragg Reflector Using Nanoporous TiO2 Thin Films

    Science.gov (United States)

    Park, Si-Hyun; Lee, Duck-Hee; Kim, Chang-Sik; Jeong, Hyun-Dam

    2011-01-01

    Distributed Bragg reflectors (DBRs) were successfully fabricated with nanoporous TiO2 thin films using the surfactant-templated method. Nanoporous TiO2 thin films with various film refractive indices and thicknesses were spin-coated onto silicon substrates using titanium(IV) butoxide Ti(OC4H9)4 as the inorganic precursor, n-butanol as the solvent, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer EO20PO70EO20 as the templating agent, and were characterized using Fourier-transform infrared spectroscopy (FT-IR), capacitance-voltage (C-V) measurements, spectroscopic ellipsometry (SE), and transmission electron microscopy (TEM). We designed and fabricated DBRs using the nanoporous TiO2 thin films, whose refractive indices and thicknesses were controlled by varying the amounts of solute and solvent, respectively. The measured reflectance for the fabricated DBRs was over 96% at a center wavelength of ˜430 nm with a flat band of about 50 nm in the resonant region and typical interference patterns in the off-resonant region for a DBR with six pairs of TiO2 thin films.

  12. 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)

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

    Science.gov (United States)

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

    2009-07-01

    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

  14. 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)

  15. A heterostructured SnO2–TiO2 thin film prepared by Langmuir–Blodgett technique

    International Nuclear Information System (INIS)

    SnO2–TiO2 heterostructure films were prepared through Langmuir–Blodgett (LB) route. LB films of octadecyl amine (ODA)–titanyl oxalate multilayer deposited on Si (100) and decomposed at 600 °C showed rutile and anatase phases of ultrathin TiO2 film. Subsequently, multilayer LB film of ODA–stannate deposited on the pre deposited TiO2 film after decomposition at 600 °C resulted in thin SnO2 films on the TiO2 thin film. The phase analysis of the SnO2–TiO2 film showed cassiterite phase of SnO2 as well as the rutile/anatase mixture of TiO2 indicating a SnO2–TiO2 heterostructured film. Surface morphology of the pure TiO2 film and SnO2–TiO2 film were analyzed by using AFM. Electrical characterization by AC impedance analysis suggested SnO2–TiO2 heterostructure formation. DC current voltage measurement showed increase in photocurrent indicating visible light absorption and efficient charge separation under the sunlight type radiation. - Highlights: • Thin film of SnO2–TiO2 heterostructure was prepared by Langmuir–Blodgett technique. • The decomposition temperature of LB film was 600 °C to form oxide thin films. • Structural and electrical properties were studied by XRD, DC and AC impedance studies. • Increase in photocurrent was observed in heterostructure film in presence of visible light

  16. Self-assembly of ordered mesoporous TiO2 thin films as photoanodes for cathodic protection of stainless steel

    International Nuclear Information System (INIS)

    Highlights: ? The ordered mesoporous TiO2 thin films were prepared on FTO substrates. ? The more effective photocathodic protection was observed for mesoporous TiO2 films. ? More negative photopotential was observed for 500 °C-calcined mesoporous TiO2 film. ? The larger photocurrent was observed for mesoporous TiO2 film calcined at 500 °C. - Abstract: In this paper, the ordered mesoporous TiO2 thin films that served as photoanodes for cathodic protection of SUS304 stainless steel (304SS) were prepared through the sol–gel and evaporation-induced self-assembly method. The as-prepared TiO2 thin films were calcined at 350 °C and 500 °C, and then characterized by scanning electron microscopy (SEM), the small-angle X-ray diffraction (SAXD) as well as the wide-angle X-ray powder diffraction (WAXD). Moreover, the photoelectrochemical properties of the mesoporous TiO2 thin films such as the open circuit potential (OCP), the photocurrent spectra as well as the Tafel polarization curves were also measured. The results showed that the more negative photopotential was observed for the mesoporous TiO2 films compared to the TiO2 films without mesoporous structures. Besides, the mesoporous TiO2 films calcined at 500 °C exhibited the more negative photopotential and larger photocurrent than that calcined at 350 °C. In conclusion, the mesoporous TiO2 esoporous TiO2 films could provide the effective photogenerated cathodic protection for 304SS.

  17. Optical Spectra of Graded Nanostructured TiO2 Chiral Thin Films

    CERN Document Server

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

    2010-01-01

    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.

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

    OpenAIRE

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

    2013-01-01

    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...

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

    International Nuclear Information System (INIS)

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

  20. Magnetic and structural study of Cu-doped TiO2 thin films

    CERN Document Server

    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

    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.

  1. Magnetic and structural study of Cu-doped TiO2 thin films

    International Nuclear Information System (INIS)

    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 Cu substitutionally replacing cations in TiO2

  2. Sputter joining of TiO2 / SiO2 thin film system

    Science.gov (United States)

    Taga, Yasunori; Yamada, Naoomi

    2011-09-01

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

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

    OpenAIRE

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

    2012-01-01

    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? f...

  4. Influence of direct current power on the photocatalytic activity of facing target sputtered TiO2 thin films

    International Nuclear Information System (INIS)

    In this investigation, transparent TiO2 films were deposited with various direct current powers, ranging from 200 W to 500 W by facing target reactive sputtering technique to study the photocatalytic activity by the measurement of photo-decomposition of methanol under UV-visible irradiation. All the as-deposited TiO2 thin films, prepared with sputtering power over 200 W, show crystalline structure of anatase phase. The crystallinity of the TiO2 thin films improves greatly with the increase of sputtering power. The photo-decomposition efficiency of TiO2 film increases monotonically with the applied power. An explanation is proposed for the variation of photocatalytic activity with varying sputtering power based on the surface morphology and crystallinity of the TiO2 thin films

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

    International Nuclear Information System (INIS)

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

  6. Low Loss Sol-Gel TiO2 Thin Films for Waveguiding Applications

    Directory of Open Access Journals (Sweden)

    Alexis Fischer

    2013-03-01

    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.

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

    Science.gov (United States)

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

    2011-04-01

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

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

    Science.gov (United States)

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

    2014-11-01

    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.

  9. 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.

  10. Photocatalysis of Thin Films of TiO2 on Al2O3 Substrates

    Science.gov (United States)

    Turbay, David; Luttrell, Timothy; Batzill, Matthias

    2013-03-01

    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.

  11. Slurry components of TiO2 thin film in chemical mechanical polishing

    Science.gov (United States)

    Bo, Duan; Jianwei, Zhou; Yuling, Liu; Chenwei, Wang; Yufeng, Zhang

    2014-10-01

    A chemical mechanical polishing (CMP) process was selected to smooth TiO2 thin film surface and improve the removal rate. Meanwhile, the optimal process conditions were used in TiO2 thin film CMP. The effects of silica sols concentration, slurry pH, chelating agent and active agent concentration on surface roughness and material removal rate were investigated. Our experimental results indicated that we got lower surface roughness (1.26 Å, the scanned area was 10 × 10 ?m2) and higher polishing rate (65.6 nm/min), the optimal parameters were: silica sols concentration 8.0%, pH value 9.0, active agent concentration 50 mL/L, chelating agent concentration 10 mL/L, respectively.

  12. Preparation of Various TiO2 Buffer Layers for YBa2Cu3O7 Thin Films

    Science.gov (United States)

    Wu, Kaung-Hsiung; Lin, Po-Iem; Hsieh, Chich-Chang; Juang, Jenh-Yih; Uen, Tseng-Ming; Gou, Yih-Shung; Lin, Jiunn-Yuan

    2001-03-01

    Titanium dioxide (TiO_2) thin films have been deposited on Si, MgO and SrTiO3 (STO) substrates by pulsed laser deposition (PLD) and dc sputtering technique. For the case of PLD, pure anatase(001) or rutile(110) TiO2 films with smooth surfaces have been obtained either by the oxidation of titanium nitride (TiN) films or by the deposition of TiO2 films directly at different temperatures and oxygen pressures. The YBa_2Cu_3O_7(YBCO) thin films then deposited sequentially on the TiO2 layers by PLD. The zero-resistance temperature (Tco) for the YBCO films deposited on TiO_2/Si(100) and TiO_2/STO(100) were 85 K and 89 K, respectively. Comparative studies of depositing YBCO films directly on to a dc sputtered TiO_2/STO(100) template commonly used in selective epitaxial growth (SEG) process have, however, resulted in non-superconducting YBCO top layer. The characteristics of the resultant TiO2 layers obtained from various processes were analyzed to delineate the apparent discrepancies. Experiments of resolving the possible interface layer formation such as Auger electron spectroscopy (AES) depth profile analyses and the interfacial x-ray absorption spectroscopy (XAS) are expected to give more insight on this matter.

  13. Photocatalytic activity of nanostructured TiO2 thin films prepared by pulsed spray pyrolysis

    International Nuclear Information System (INIS)

    Nano-structured TiO2 thin films were deposited onto soda lime glass by the pneumatic spray pyrolysis method from a peroxo-titanium complex solution. Samples were prepared spraying 10 s the complex solution followed by an interruption of 20 s in order to avoid inadequate substrate cooling, the substrate temperature was varied from 230 to 430 oC in 50 oC steps. Amorphous as-deposited films crystallized to the anatase phase after an annealing process at 500 oC for 3 h. The photocatalytic activity of the nanostructured TiO2 thin films was studied under UV irradiation with the degradation of methylene-blue. Amorphous as-deposited TiO2 films prepared at low substrate temperatures (280 oC) showed the best photocatalytic activity, but after the annealing process films exhibit a decrease in the photocatalytic activity due to both the increase in the grain size and the decrease in the surface area. (author)

  14. 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)

  15. 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

  16. Synthesis and hydrophilic properties of Mo doped TiO2 thin films

    Science.gov (United States)

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

    2014-06-01

    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.

  17. Nanoporous TiO2 thin film based conductometric H2 sensor

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  19. Characteristics and properties of TiO2 thin film photocatalysts fabricated by sol-gel process

    International Nuclear Information System (INIS)

    Transparent TiO2 thin films have been prepared through a sol-gel process on the surface of glass pipes and characterized by XRD, Raman, UV-Vis and XPS in this paper. Results show that the absorption of the samples calcined at 773 K is obviously stronger than that calcined at 573 K between 290 and 330 nanometer. The films heated at 573 K are still in amorphous state but show good photocatalytic activities. With the increasing of heating temperature, the photocatalytic activities of TiO2 films decrease gradually. In addition, photocatalytic activity of TiO2 films increases gradually with the increment of coating cycles. (authors)

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

    Directory of Open Access Journals (Sweden)

    H D CHANDRASHEKARA

    2014-04-01

    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.

  1. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    Science.gov (United States)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  2. The effect of heat treatment on superhydrophilicity of TiO2 nano thin films

    Science.gov (United States)

    Ashkarran, A. A.; Mohammadizadeh, M. R.

    2007-11-01

    TiO2 thin films were synthesized 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 166nm 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 10min under 2mW/cm2 UV irradiation. Water droplet on TiO2 thin film on Si(111), Si(100), and quartz substrates is spread to smaller angles rather than glass and polycrystalline Si substrates under UV irradiation.

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

    Scientific Electronic Library Online (English)

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

    2013-08-01

    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.

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

    International Nuclear Information System (INIS)

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

  5. Improved performance of dense TiO2/CdSe coupled thin films by low temperature process

    International Nuclear Information System (INIS)

    Dense TiO2 and TiO2/CdSe coupled nanocrystalline thin films were synthesized onto ITO coated glass substrate by chemical route at relatively low temperature (?100 deg C). TiO2 films were nanocrystalline and crystallinity disappears after CdSe deposition as evidenced by X-ray powder diffraction. Surface morphology and physical appearance of films were studied from SEM and actual photo-images, reveals dense nature of TiO2 (10-12 nm spherical grains, faint violet) and CdSe (80-90 nm spherical grains, deep brown), respectively. Presence of two absorption edges in UV spectra implies existence of separate phases rather than composite formation. TiO2 film was found to have higher water contact angle (71 deg ) than TiO2/CdSe (61 deg ) and CdSe (56 deg ). I-V and stability tests of photo-electrochemical cells were performed with TiO2 and TiO2/CdSe film electrodes (under light of illumination intensity 80 mW/cm2) in lithium iodide as an electrolyte using two-electrode system

  6. Surface nanostructuring of TiO2 thin films by ion beam irradiation

    International Nuclear Information System (INIS)

    This work reports a procedure to modify the surface nanostructure of TiO2 anatase thin films through ion beam irradiation with energies in the keV range. Irradiation with N+ ions leads to the formation of a layer with voids at a depth similar to the ion-projected range. By setting the ion-projected range a few tens of nanometers below the surface of the film, well-ordered nanorods appear aligned with the angle of incidence of the ion beam. Slightly different results were obtained by using heavier (S+) and lighter (B+) ions under similar conditions

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

    Science.gov (United States)

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

    2013-01-01

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

  8. Characterization of ultra-thin TiO2 films grown on Mo(112)

    International Nuclear Information System (INIS)

    Ultra-thin TiO2 films were grown on a Mo(112) substrate by stepwise vapor depositing of Ti onto the sample surface followed by oxidation at 850 K. X-ray photoelectron spectroscopy showed that the Ti 2p peak position shifts from lower to higher binding energy with an increase in the Ti coverage from sub- to multilayer. The Ti 2p peak of a TiO2 film with more than a monolayer coverage can be resolved into two peaks, one at 458.1 eV corresponding to the first layer, where Ti atoms bind to the substrate Mo atoms through Ti-O-Mo linkages, and a second feature at 458.8 eV corresponding to multilayer TiO2 where the Ti atoms are connected via Ti-O-Ti linkages. Based on these assignments, the single Ti 2p3/2 peak at 455.75 eV observed for the Mo(112)-(8 x 2)-TiO x monolayer film can be assigned to Ti3+, consistent with our previous results obtained with high-resolution electron energy loss spectroscopy

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

    OpenAIRE

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

    1990-01-01

    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...

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

    Science.gov (United States)

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

    2014-11-01

    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.

  11. TiO2 thin film growth using the MOCVD method

    Scientific Electronic Library Online (English)

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

    2001-07-01

    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.

  12. TiO2 thin film growth using the MOCVD method

    Directory of Open Access Journals (Sweden)

    Bernardi M.I.B.

    2001-01-01

    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.

  13. Photocatalytic antibacterial performance of Sn4+-doped TiO2 thin films on glass substrate

    International Nuclear Information System (INIS)

    Pure anatase, nanosized and Sn4+ ion doped titanium dioxide (TiO2) particulates (TiO2-Sn4+) were synthesized by hydrothermal process. TiO2-Sn4+ was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn4+ doping to TiO2 against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO2-Sn4+ in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO2-Sn4+ is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO2-Sn4+ from 10 to 50% in the coating solution increased antibacterial effect

  14. 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

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

    International Nuclear Information System (INIS)

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

  16. 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

  17. Remarkable enantioselectivity of molecularly imprinted TiO2 nano-thin films

    International Nuclear Information System (INIS)

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

  18. Preparation and Characterization of TiO2-SiO2 Thin Films

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-02-01

    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

  20. Transport properties of (Sn, Ti)O2 polycrystalline ceramics and thin films

    International Nuclear Information System (INIS)

    Polycrystalline ceramics of (Sn,Ti)O2 were prepared by the impregnation of TiO2 with SnCl4 in the presence of NH3 aq. Rf reactive sputtering from Ti-Sn metallic target was used to deposit thin films. The re-equilibration kinetics were monitored by measuring dc electrical conductivity as a function of temperature, 850 K 15 Pa 2) -5 Pa. The chemical diffusion coefficient was found to be independent of p(O2). A constant value of the activation energy of 0.7-0.8 eV was derived from the temperature dependence of the chemical diffusion coefficient. (author)

  1. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    Science.gov (United States)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

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

    OpenAIRE

    Cheng, Yajun

    2007-01-01

    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...

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

    Science.gov (United States)

    Saif, M.; El-Molla, S. A.; Aboul-Fotouh, S. M. K.; Hafez, H.; Ibrahim, M. M.; Abdel-Mottaleb, M. S. A.; Ismail, L. F. M.

    2013-08-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Young-Hee Joo

    2012-06-01

    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.

  6. TiO2 thin films and their hydrophilicity by chemical vapor deposition method

    International Nuclear Information System (INIS)

    Thin TiO2 layers were grown on glass substrates using chemical vapor deposition method. The layers are mechanically strong and possess a nanno porous morphology. The layer thickness in about 20 nm. The layers consist of anatase crystalline TiO2 and have a good hydrophilicity performance.

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

    International Nuclear Information System (INIS)

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

  8. 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.

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

    International Nuclear Information System (INIS)

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

  10. Effects of 1064 nm laser on the structural and optical properties of nanostructured TiO2 thin film

    Science.gov (United States)

    Aslam Farooq, W.; Atif, M.; Ali, Syed Mansoor; Fatehmulla, Amanullah; Aslam, M.

    2014-09-01

    TiO2 thin film has been widely used as photoelectrode in dye-sensitized solar cells. It can also be used in quantum dot synthesized solar cells. Study of its effects in different spectrum of light is important for its use in solar cells. We have reported effects of 1064 nm laser on the surface morphology, structural and optical properties of nanostructured TiO2 thin film deposited on glass substrates using sol-gel spin coating technique. Q-Switched Nd:YAG pulsed laser at various power densities is used in this study. Surface morphology of the film is investigated using X-ray diffraction (XRD) and atomic force microscopy technique. The XRD pattern of as deposited TiO2 thin film is amorphous and after laser exposure it became TiO2 anatase structure. Atomic force microscopy of the crystalline TiO2 thin film shows that the grain size increases by increasing laser power density. The calculations of the band gap are carried out from UV/Visible spectroscopy measurements with JASCO spectrometer. For laser power density of 25 MW/cm2 there is an increase in the transmission and it decreases at the value of 38 MW/cm2 and band gap decreases with increasing laser power density. Photoluminescence spectra of the crystalline TiO2 thin film indicate two broad peaks in the range of 415 and 463 nm, one for band gap peak (415 nm) and other for oxygen defect during film deposition process.

  11. 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)

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

    Science.gov (United States)

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

    2014-12-01

    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.

  13. 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

  14. Preparation and photocatalytic properties of La-doped TiO2/ZrTiO4 heterogeneous thin films

    International Nuclear Information System (INIS)

    The nano-scaled La-doped TiO2/ZrTiO4 (TL x/ZT) heterogeneous thin films were prepared by sol-gel spin-coating technique. The films were characterized by X-ray diffraction (XRD), atom force microscope (AFM) and UV-vis spectroscopy. XRD results showed that both the pure and La-doped TiO2 films were anatase phase and oriented predominantly to the (1 0 1) plane. La-doping was shown to extend the absorptivity of the heterogeneous films into the visible, which could be observed from the UV-vis spectra. The photocatalytic activity of TiO2/ZrTiO4 heterogeneous films enhanced greatly after La-doping, and reached the highest when the La dopant concentration was 0.5 mol%

  15. Preparation and characterization of thin films of TiO2PbO and TiO2Bi2O3 compositions

    OpenAIRE

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

    1990-01-01

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

  16. Preparation and characterization of V2O5 doped SiO2-TiO2 thin films

    Science.gov (United States)

    Nocu?, Marek; Kwa?ny, S?awomir

    2012-03-01

    In our investigation, V doped SiO2/TiO2 thin films were prepared on glass substrates by dip coating sol-gel technique. Chemical composition of the samples was studied by X-ray photoelectron spectroscopy (XPS). Transmittance of the samples was characterized using UV-VIS spectrophotometry. Subsequently band-gap energy (Eg) was estimated for these films. Powders obtained from sols were characterized by FTIR spectroscopy. It was found that vanadium decreases optical band gap of SSiO2/TiO2 films.

  17. Improved performance of CdSe quantum dot-sensitized TiO2 thin film by surface treatment with TiCl4

    International Nuclear Information System (INIS)

    A TiO2 nanocrystalline thin film, sensitized by CdSe quantum dots, was further modified by a TiCl4 treatment strategy. The CdSe quantum dots with a cubic zinc blende structure were synthesized in situ on the TiO2 nanocrystalline thin films by chemical bath deposition, after which the sensitized TiO2 film was further modified by a TiCl4 treatment strategy. The modification of the amorphous TiO2 thin layer enhanced the photovoltaic performance of the quantum dot-sensitized thin film. This enhancement was detected by fabricating a solar cell based on the sensitized thin film electrode, a polysulfide electrolyte and a platinized electrode. The modified amorphous TiO2 was partly crystallized by heating the film at 200 °C to analyze the effect of crystallization on interfacial recombination and the photovoltaic performance. The enhancement due to the TiCl4 treatment was attributed to the formation of an amorphous TiO2 thin layer, which separated the uncovered surface of TiO2 nanoparticles from the electrolyte, and reduced the surface states of the TiO2 nanocrystals and the quantum dots. The highest conversion efficiency was 2.13%, and it was obtained for the quantum dot-sensitized solar cell after optimizing the CdSe quantum dot deposition and amorphous TiO2 thin layer modification processes.

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

    Science.gov (United States)

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

    2011-12-01

    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.

  19. Surface Plasmons and Optical Properties of TiO2/X(X = Au and Ag) Nanostructure Thin Films

    Science.gov (United States)

    Zolanvari, A.; Sadeghi, H.; Norouzi, R.; Ranjgar, A.

    2013-09-01

    TiO2/X(X = Au and Ag) nanolayers are fabricated by depositing TiO2 films using rf magnetron sputtering on thin quartz substrates embedded with Au and Ag nanoparticles. Enhancement of light absorption of the nanostructural layers is observed. These plasmonic and non-plasmonic materials are ordered in geometric arrangements with dimensions that are fractions of the wavelength of light. The light absorption enhancement of synthesized structure in comparison to TiO2 is originated from near-field enhancement caused by the plasmonic effect of metallic nanoparticles, which can be demonstrated by the optical absorption spectra. We show that plasmon modes can exist for the infrared region of the optical spectrum. Also, we analyze the optical properties of the metal-insulator films, in order to clarify the role of metal inclusions in the TiO2 dielectric matrix. Optical band gaps of the nanolayer films are calculated by using Tauc's relation, and the n values of optical band gaps with the variation composition are found from 1.80 to 3.69 eV. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of TiO2/X(X=Au and Ag) nanolayers enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

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

    Directory of Open Access Journals (Sweden)

    Emerson Henrique de Faria

    2007-12-01

    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.

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

    Scientific Electronic Library Online (English)

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

    2007-12-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Brus V. V.

    2010-10-01

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

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

    Science.gov (United States)

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

    2014-10-01

    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

  4. Investigation on surface roughness in chemical mechanical polishing of TiO2 thin film

    Science.gov (United States)

    Bo, Duan; Jianwei, Zhou; Yuling, Liu; Chenwei, Wang; Yufeng, Zhang

    2014-06-01

    Surface roughness by peaks and depressions on the surface of titanium dioxide (TiO2) thin film, which was widely used for an antireflection coating of optical systems, caused the extinction coefficient increase and affected the properties of optical system. Chemical mechanical polishing (CMP) is a very important method for surface smoothing. In this polishing experiment, we used self-formulated weakly alkaline slurry. Other process parameters were working pressure, slurry flow rate, head speed, and platen speed. In order to get the best surface roughness (1.16 Å, the scanned area was 10 × 10 ?m2) and a higher polishing rate (60.8 nm/min), the optimal parameters were: pressure, 1 psi; slurry flow rate, 250 mL/min; polishing head speed, 80 rpm; platen speed, 87 rpm.

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

    OpenAIRE

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

    2012-01-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube ...

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

    Directory of Open Access Journals (Sweden)

    Isrihetty Senain

    2010-12-01

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

  7. Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO2 thin films

    Science.gov (United States)

    Ren, Fu-jian; Yu, Xiao-bai; Ling, Yun-han; Feng, Jia-you

    2012-05-01

    In-situ pure TiO2 and Fe-doped TiO2 thin films were synthesized on Ti plates via the micro-arc oxidation (MAO) technique. The as-fabricated anatase TiO2 thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO2 thin films by adding precursor K4(FeCN)6·3H2O into the Na3PO4 electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of K4(FeCN)6·3H2O increasing, eventually affecting the ethanol sensing performances of TiO2 thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant (1.28at%), by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275°C. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe3+ substituting for Ti4+.

  8. Characterization of the boundaries of thin films of TiO2 by atomic force microscopy and optical methods.

    Czech Academy of Sciences Publication Activity Database

    Franta, D.; Ohlídal, I.; Klapetek, P.; Pokorný, Pavel

    2002-01-01

    Ro?. 34, - (2002), s. 759 - 762. ISSN 0142-2421 R&D Projects: GA ?R GA101/01/1104 Institutional research plan: CEZ:AV0Z2065902 Keywords : optical characterization * TiO 2 thin films * bonduary roughness Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.071, year: 2002

  9. 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

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

    OpenAIRE

    Luo, Wenxiu; Tan, Zhongke

    1989-01-01

    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.

  11. 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.

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

    Science.gov (United States)

    Gupta, Sanjeev K.; Singh, Jitendra; Anbalagan, K.; Kothari, Prateek; Bhatia, Ravi Raj; Mishra, Pratima K.; Manjuladevi, V.; Gupta, Raj K.; Akhtar, J.

    2013-01-01

    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 Å/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (1 0 0) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV-visible Spectroscopy (UV-vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO2 layer between TiO2 and the substrate and the minor anatase crystalline phase of TiO2 was also identified in FTIR analysis. Grain size was found to be in the range of 100-125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO2 target to thin film.

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

    Science.gov (United States)

    Jung, Sung-Hoon; Kang, Sang-Won

    2001-05-01

    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.

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

    Science.gov (United States)

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

    2008-05-01

    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

  15. Photocatalytic degradation of spill oils on TiO2 nanotube thin films

    International Nuclear Information System (INIS)

    The nitrogen-doped TiO2 nanotube (N-TNT) thin films were synthesized using ZnO nanorods as the template and doped with urea at 623 K. Under ultraviolet (UV) and visible light irradiation, the efficiencies for photocatalytic degradation of methylene blue is as high as 30%. About 10% of toluene (representing aromatics in the spill oils) in sea water can be photocatalytically degraded under visible light radiation for 120 min. The aliphatic model compound (1-hexadecene) has, on the contrary, a less efficiency (8%) on the N-TNT photocatalyst. On the average, under visible light radiation, the effectnesses of the N-TNT for photocatalytic degradation of model compounds in the spill oils in sea water are 0.38 mg toluene/gN-TNT h and 0.25 mg 1-hexadecene/gN-TNT h. It is expected that spill oils in the harbors or seashores can be adsorbed and photocatalytically degraded on the N-TNT thin films that are coated onto levee at the sea water surface level

  16. Photovoltaic Performance Improvement of Dye-Sensitized Solar Cells Based on Mg-Doped TiO2 Thin Films

    International Nuclear Information System (INIS)

    Mg salts [Mg(NO3)2·6H2O]-doped TiO2 electrodes prepared well-optimized by the hydrothermal method. To prepare the working electrode, the TiO2 or Mg-doped TiO2 slurry was coated onto the fluorine-doped tin oxide glass substrate by the doctor blade method and was then sintered at 450 °C. X-ray photoelectron spectroscopy (XPS) data indicated that the doped Mg ions exist in form of Mg2+, which can play a role as e? or h+ traps and reduce e?/h+ pair recombination rate, The Mott-Schottky plot indicates that the Mg-doped TiO2 photoanode shifts the flat band potential positively. The positive shift of the flat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2. This study show a photovoltaic efficiency of 7.12%, which is higher than that of the undoped TiO2 thin film (5.62%) and increase short-current by 26.7% from 14.9 mA to 19.1 mA

  17. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  19. 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

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

    OpenAIRE

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

    2013-01-01

    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...

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

    Science.gov (United States)

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

    2013-04-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. PMID:23827596

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

    Science.gov (United States)

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

    2014-01-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. PMID:23827596

  3. C ion-implanted TiO2 thin film for photocatalytic applications

    Science.gov (United States)

    Impellizzeri, G.; Scuderi, V.; Romano, L.; Napolitani, E.; Sanz, R.; Carles, R.; Privitera, V.

    2015-03-01

    Third-generation TiO2 photocatalysts were prepared by implantation of C+ ions into 110 nm thick TiO2 films. An accurate structural investigation was performed by Rutherford backscattering spectrometry, secondary ion mass spectrometry, X-ray diffraction, Raman-luminescence spectroscopy, and UV/VIS optical characterization. The C doping locally modified the TiO2 pure films, lowering the band-gap energy from 3.3 eV to a value of 1.8 eV, making the material sensitive to visible light. The synthesized materials are photocatalytically active in the degradation of organic compounds in water under both UV and visible light irradiation, without the help of any additional thermal treatment. These results increase the understanding of the C-doped titanium dioxide, helpful for future environmental applications.

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

    International Nuclear Information System (INIS)

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

  5. 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

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

    International Nuclear Information System (INIS)

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

  7. Electrophoretic deposited TiO2 pigment-based back reflectors for thin film solar cells.

    Science.gov (United States)

    Bills, Braden; Morris, Nathan; Dubey, Mukul; Wang, Qi; Fan, Qi Hua

    2015-02-01

    Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This work reports titanium dioxide (TiO2) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si solar cell. Electrophoretic deposition is used to produce pigment-based back reflectors with high pigment density, controllable film thickness and site-specific deposition. Electrical conductivity of the pigment-based back reflectors is improved by creating electrical vias throughout the pigment-based back reflector by making holes using an electrical discharge / dielectric breakdown approach followed by a second electrophoretic deposition of conductive nanoparticles into the holes. While previous studies have demonstrated the use of pigment-based back reflectors, for example white paint, on glass superstrate configured thin film Si solar cells, this work presents a scheme for producing pigment-based reflectors on complex shape and flexible substrates. Mechanical durability and scalability are demonstrated on a continuous electrophoretic deposition roll-to-roll system which has flexible metal substrate capability of 4 inch wide and 300 feet long. PMID:25836255

  8. Properties of sputtered TiO2 thin films as a function of deposition and annealing parameters

    Science.gov (United States)

    Pjevi?, Dejan; Obradovi?, Marko; Marinkovi?, Tijana; Grce, Ana; Milosavljevi?, Momir; Grieseler, Rolf; Kups, Thomas; Wilke, Marcus; Schaaf, Peter

    2015-04-01

    The influence of sputtering parameters and annealing on the structure and optical properties of TiO2 thin films deposited by RF magnetron sputtering is reported. A pure TiO2 target was used to deposit the films on Si(100) and glass substrates, and Ar/O2 gas mixture was used for sputtering. It was found that both the structure and the optical properties of the films depend on deposition parameters and annealing. In all cases the as-deposited films were oxygen deficient, which could be compensated by post-deposition annealing. Changes in the Ar/O2 mass flow rate affected the films from an amorphous-like structure for samples deposited without oxygen to a structure where nano-crystalline rutile phase is detected in those deposited with O2. Annealing of the samples yielded growth of both, rutile and anatase phases, the ratio depending on the added oxygen content. Increasing mass flow rate of O2 and annealing are responsible for lowering of the energy band gap values and the increase in refractive index of the films. The results can be interesting towards the development of TiO2 thin films with defined structure and properties.

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

    Directory of Open Access Journals (Sweden)

    R.SHASHIDHAR

    2013-04-01

    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.

  10. Effect of the nanocrystalline structure type on the optical properties of TiO2:Nd (1 at.%) thin films

    Science.gov (United States)

    Mazur, Michal; Wojcieszak, Damian; Kaczmarek, Danuta; Domaradzki, Jaroslaw; Zatryb, Grzegorz; Misiewicz, Jan; Morgiel, Jerzy

    2015-04-01

    Titanium dioxide thin films, each doped with the same amount of neodymium (1 at.%) were deposited by Low Pressure Hot Target Reactive Sputtering and High Energy Reactive Magnetron Sputtering processes in order to obtain anatase and rutile thin film structures respectively. The microstructure and phase composition were analyzed using the transmission electron microscopy method including high resolution electron microscopy imaging. The measurements of the optical properties showed, that both prepared thin films were transparent in the visible light range and had a low extinction coefficient of ca. 3 ? 10-3. The thin film with the anatase structure had a lower cut-off wavelength and refractive index and a higher value of optical energy band gap as-compared to the TiO2:Nd coating with the rutile structure. Simultaneously, more efficient photoluminescence emission was observed for the rutile thin films.

  11. Preparation and characterization of nanocrystalline TiO2 thin films

    International Nuclear Information System (INIS)

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

  12. 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.

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

    Science.gov (United States)

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

    2013-09-01

    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.

  14. Investigation of structure and properties of N-doped TiO2 thin films grown by APCVD

    International Nuclear Information System (INIS)

    Using TiCl4, O2, and NH3 as gas precursors, N-doped titanium dioxide films with large areas and continuous surfaces were deposited by atmospheric pressure chemical vapor deposition (APCVD). Measurements were performed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet visible (UV-vis) transmission spectra. Using NH3 as the N-doping source, Ti4O7 is induced into the thin films, and anatase-rutile transformation is inhibited. Compared to pure TiO2, N-doped TiO2 films deposited with lower NH3 flows (2 films by APCVD with low cost and high deposition rate (150 nm/min) is compatible with float glass processing, and has a potential industrial application

  15. Visible-light photocatalytic activity of N/SiO2–TiO2 thin films on glass

    International Nuclear Information System (INIS)

    Nanocrystalline N-doped SiO2/TiO2 visible-light photocatalyst thin films were synthesized using the sol-gel method on glass substrates. The synthesized catalysts were then characterized using several analytical techniques like x-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and UV–vis absorption spectroscopy (UV–vis). The experimental results revealed that the maximum optical response of the synthesized SiO2/TiO2 thin films shifted from the ultraviolet (UV) to the visible-light region (??420?nm). The photocatalytic activity of N-doped SiO2–TiO2 photocatalyst was considerably higher than that of SiO2–TiO2, and this result was obtained with an optimal concentration of 40?mol% of N. The enhanced photocatalytic activity was attributed to the increasing surface area and forming more hydroxyl groups in the doped catalyst

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

    Science.gov (United States)

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

    2015-01-01

    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 %.

  17. Evolution of structural and optical properties of photocatalytic Fe doped TiO2 thin films prepared by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Undoped and Fe doped TiO2 thin films have been prepared by RF magnetron sputtering. Pure TiO2 thin film exhibited an amorphous-like nature. With increase in iron concentration (0–0.1 at%), the films exhibited better crystallization to anatase phase . Red shift of absorption edge was observed in the UV-vis transmittance spectra . At higher Fe concentration (0.5 at%), onset of phase transformation to rutile is noticed. Photocatalytic properties of pure and 0.1 at% Fe doped TiO2 thin films were investigated by degradation of methylene blue in UV light, visible light and light from Hg vapor lamp. 70% degradation of methylene blue was observed in the presence of Fe doped film in comparison with 3% degradation in presence of pure TiO2 film when irradiated using visible light for 2 h

  18. Preparation and characterization of TiO 2 thin films using vacuum ultraviolet light in a sol-gel process

    Science.gov (United States)

    Katsumata, Ken-ichi; Nakajima, Akira; Yoshida, Naoya; Watanabe, Toshiya; Kameshima, Yoshikazu; Okada, Kiyoshi

    2005-12-01

    In the current work, we prepared TiO 2 thin films using vacuum ultraviolet (VUV) irradiation of several different intensities before firing. We then investigated effects of VUV intensity and alkoxide mixtures on the microstructural evolution of the films. The microstructure of the film without VUV treatment comprises uniform anatase grains. Grains in films with VUV irradiation gradually form a domain-like microstructure with increasing VUV intensity. The heterogeneous hydrolysis rate in the mixed alkoxide will trigger formation of the domain-like microstructure.

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

    International Nuclear Information System (INIS)

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

  20. Growth of high quality rutile TiO2 thin film using ZnO buffer layer on Si(100) substrate

    International Nuclear Information System (INIS)

    The TiO2 rutile thin films were grown on Si(100) substrates with ZnO buffer layer at a substrate temperature of 500 oC by radio frequency (rf) magnetron sputtering. In order to investigate the effect of buffer layer thickness on the growth of the TiO2 film, the ZnO buffer layers were deposited in the thickness range of 70-150 nm. The thickness of the TiO2 films was about 200 nm identical for all the samples. The crystal structure of the buffer layers and the TiO2 thin films was characterized by X-ray diffractometer (XRD). The XRD spectra confirmed that TiO2 rutile film with high crystalline quality was achieved on the ZnO buffer layer, which had a great relation to the improvement of the crystalline quality of the ZnO buffer layer. The surface morphologies of the TiO2 rutile thin films were evaluated by atomic force microscopy (AFM). The roughness of the TiO2 thin films became smoother as the thickness of the ZnO buffer layer increased

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Eshaghi A.

    2013-09-01

    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.

  3. 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.

  4. Potentiostatic reversible photoelectrochromism: an effect appearing in nanoporous TiO2/Ni(OH)2 thin films.

    Science.gov (United States)

    Cibrev, Dejan; Jankulovska, Milena; Lana-Villarreal, Teresa; Gómez, Roberto

    2014-07-01

    In the field of energy saving, finding composite materials with the ability of coloring upon both illumination and change of the applied electrode potential keeps on being an important goal. In this context, chemical bath deposition of Ni(OH)2 into nanoporous TiO2 thin films supported on conducting glass leads to electrodes showing both conventional electrochromic behavior (from colorless to dark brown and vice versa) together with photochromism at constant applied potential. The latter phenomenon, reported here for the first time, is characterized by fast and reversible coloration upon UV illumination. The bleaching kinetics shows first order behavior with respect to the Ni(III) centers in the film, and an order 1.2 with respect to electrons in the TiO2 film. From a more applied point of view, this study opens up the possibility of having two-mode smart windows showing not only conventional electrochromism but also reversible darkening upon illumination. PMID:24926989

  5. Production of multicharged iron and nitrogen ions and application to enhance photo-catalytic performance in visible light region on TiO2 thin films

    International Nuclear Information System (INIS)

    Multicharged iron and nitrogen ions have been produced from solid materials in a 2.45 GHz electron cyclotron resonance (ECR) ion source (TAIKO device, Toyama Prefectural University), and also large area TiO2 thin films are individually produced by reactive sputtering in an arched ECR plasma. We normally form the TiO2 thin film (?100 nm) on the Si(1 0 0) substrates. We measure the X-ray diffraction for characterization of the TiO2 crystallinity and the contact angle of distilled water for estimation of photo-catalytic performance. The crystalline TiO2 thin films are anatase and rutile phases. Fe3+ and N3+ ions were implanted into TiO2 thin films on the Si substrates in order to enhance photo-catalytic performance in visible light region. The maximum efficiency of photo-catalytic performance has been obtained at the dose of about 2 x 1015 cm-2. We compared contact angles of distilled water on the TiO2 by illuminating fluorescent light for four hours before and after implantation. Photo-catalytic performance of the TiO2 thin film in visible light region after implantation is better than that before implantation without deterioration in ultraviolet light region

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

    International Nuclear Information System (INIS)

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

  7. Enhancement of crystallinity and optical properties of bilayer TiO2/ZnO thin films prepared by atomic layer deposition.

    Science.gov (United States)

    Hussin, Rosniza; Choy, Kwang-Leong; Hou, Xianghui

    2011-09-01

    Bilayer and multilayer thin films are becoming increasingly important in the development of faster, smaller and more efficient electronic and optoelectronic devices. One of the motivations of applying bilayer or multilayer structures is to modify the optical properties of materials. Atomic layer deposition (ALD) is a variant of Chemical Vapour Deposition that can produce uniform and conformal thin films with well controlled nanostructures. In this study, we have demonstrated new findings of the use of ALD fabricated bilayer TiO2/ZnO thin films with enhanced crystallinity and optical properties. TiO2 films have been deposited at 300 degrees C for 1000 (51 nm in thickness) or 3000 (161 nm in thickness) deposition cycles onto glass and Si substrates. ZnO films are subsequently deposited on the TiO2 layers at 280 degrees C for 500 deposition cycles (55 nm). The crystallinity and optical properties of the TiO2/ZnO thin films have been analysed by X-ray diffraction, photoluminescence, UV-Vis spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. XRD diffraction pattern confirmed the presence of ZnO with wutrtize crystal structure and TiO2 with anatase structure. It shows that the crystallinity of the TiO2 films has been improved with the deposition of ZnO. The intensity of UV luminescence has increased by almost 30% for TiO2/ZnO bilayer as compared to the single layer TiO2. The possible mechanism for the enhancement of the optical properties of bilayer TiO2/ZnO thin films will be discussed. PMID:22097544

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

    International Nuclear Information System (INIS)

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

  9. Growth, differentiation, and migration of osteoblasts on transparent Ni doped TiO2 thin films deposited on borosilicate glass.

    Science.gov (United States)

    Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Kant, Chander; Pandey, Ravi Ranjan; Govind; Saini, Krishan Kumar; Pande, Gopal

    2012-05-01

    A simple and cost effective dip coating method was used to deposit thin films of amorphous (AM) or anatase (AN) titanium dioxide (TiO(2)) on borosilicate glass substrates, either with or without prior doping of TiO(2) with nickel (Ni) cations by a specially designed sol gel technique. The objective of the study was to compare the physicochemical and biological properties of these films and assess their use in orthopedic implants or for in vitro cell biological studies. Analytical techniques such as XRD and XPS, in combination with ATR-FTIR and SEM revealed that only AN films, prepared by controlled heating up to 450°C, irrespective of prior doping with Ni, contained significant crystalline structures of variable morphologies. This observation could be linked to the carbon and oxygen contents and the availability of functional groups in the films. Cell biological studies revealed that Ni doping of TiO(2) in both AM and AN films improved the adhesion, spreading, proliferation, differentiation, and migration of MC3T3 cells. Our studies provide a new approach to prepare optically transparent metal surfaces, with tunable physicochemical properties, which could be suitable for eliciting optimal osteoinductive cell responses and permit the detailed in vitro cell biological studies of osteoblasts. PMID:22337701

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

    International Nuclear Information System (INIS)

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

  11. Influence of O2 partial pressure on the growth of nanostructured anatase phase TiO2 thin films prepared by DC reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Research highlights: ? Growth of crystalline anatase TiO2 can be controlled by % O2 and sputtering power. ? Agglomeration of TiO2 nano-sized grains is observed and rises with decrease in % O2. ? Nano-sized grains promote the formation of porous TiO2 films. ? Deposition parameters have great influence on the optical properties of TiO2 films. - Abstract: Nanostructured titanium dioxide (TiO2) thin films were deposited on unheated glass substrates by DC reactive magnetron sputtering. The influence of the oxygen percentage in the discharge and the sputtering power (P) on the phase composition, crystallinity, surface morphology and optical properties of the films was investigated. The structure of the as-sputtered TiO2 films prepared in different oxygen concentrations for P = 500 W and 1000 W varies from amorphous to crystalline. X-ray diffraction revealed that, excluding the lowest oxygen concentration (1% O2), all annealed TiO2 thin films at 400 deg. C/4 h have an anatase crystal structure and the crystallinity decreases with the oxygen percentage. However, for 5 and 10% O2, the films are textured with the (1 0 1) crystal direction normal to the substrate surface and for O2 ? 15% the films have the preferred orientation (0 0 4), which is accounted for different surface energies associated with different planes. Field emission scannent planes. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) evidence distinct modifications in the morphology of the thin films which are corroborated with the crystallite sizes estimated from the typical diffraction peaks. Agglomeration of smaller TiO2 nano-sized grains to form bigger sized particulates is observed and enhanced by the decrease in oxygen content. With the variation in oxygen concentration, the optical properties (refractive index and optical band gap) of TiO2 films also change strongly being dependent on crystallinity, crystallite size and oxygen vacancies.

  12. 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.

  13. 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.

  14. Preparation and third order nonlinear optical property of rhodamine-6G-doped SiO2-TiO2 sol-gel thin films

    Science.gov (United States)

    Zhang, Xiyan; Cao, Zhifeng; Yang, Kuisheng; Long, Gaoqun

    1998-02-01

    Sol-gel dip coating method was adopted to prepare Rhodamine-6G doped SiO2-TiO2 thin films. Effects of MTMS/TEOS ratio on the crack of the thin films during drying stage were studied. The cracking was greatly decreased with the increase of MTMS/TEOS ratio. Crack free thin films were obtained for the samples with MTMS/TEOS greater than 0.75. The optical absorption and fluorescence spectra of the thin films were recorded. The refractive index increases linearly with the increase of TiO2 content (20, 40, 60 mol%). The third order nonlinear susceptibility of the Rhodamine-6G doped SiO2-TiO2 thin films is (chi) (3) approximately equals 10-9 esu measured by the generate four wave mixing technique.

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

    Science.gov (United States)

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

    2012-08-01

    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%.

  16. 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.

  17. Photocatalytic activity of hydrophobized mesoporous thin films of TiO2

    Czech Academy of Sciences Publication Activity Database

    Wark, M.; Tschirch, J.; Bartels, O.; Bahnemann, D.; Rathouský, Ji?í

    2005-01-01

    Ro?. 84, 1-3 (2005), s. 247-253. ISSN 1387-1811 R&D Projects: GA ?R GA203/03/0824; GA ?R GA203/01/0617 Grant ostatní: Deutsche Forschungsgemeintschaft(DE) WA 1116/7-1; DAAD(DE) D/04/25758 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous TiO 2 films * hydrophobicity * photocatalysis * decomposition of dyes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.355, year: 2005

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

    Directory of Open Access Journals (Sweden)

    M. Horprathum

    2010-01-01

    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.

  19. Investigation of thin TiO2 films cosputtered with Si species

    International Nuclear Information System (INIS)

    Titanium dioxide (TiO2) films were fabricated by cosputtering titanium (Ti) target and SiO2 or Si slice with ion-beam-sputtering deposition (IBSD) technique and were postannealed at 450 deg. C for 6 h. The variations of oxygen bonding, which included high-binding-energy oxygen (HBO), bridging oxygen (BO), low-binding-energy oxygen (LBO), and three chemical states of titanium (Ti4+, Ti3+ and Ti2+) were analyzed by X-ray photoelectron spectroscopy (XPS). The enhancement of HBO and reduction of BO in O 1s spectra as functions of SiO2 or Si amount in cosputtered film imply the formation of Si-O-Ti linkage. Corresponding increase of Ti3+ in Ti 2p spectra further confirmed the property modification of the cosputtered film resulting from the variation of the chemical bonding. An observed correlation between the chemical structure and optical properties, refractive index and extinction coefficient, of the SiO2 or Si cosputtered films demonstrated that the change of chemical bonding in the film results in the modification of optical properties. Furthermore, it was found that the optical properties of the cosputtered films were strongly depended on the cosputtering targets. In case of the Si cosputtered films both the refractive indices and extinction coefficients were reduced after postannealing, however, the opposite trend was observed in SiO2 cosputtered films. cosputtered films.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  3. Sol-gel synthesis, characterization and optical properties of mercury-doped TiO2 thin films deposited on ITO glass substrates

    International Nuclear Information System (INIS)

    The Hg-doped and undoped nano-crystalline TiO2 films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO2 were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO2, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 oC. The average crystallite size of the undoped TiO2 films was about 8.17 nm and was increased with Hg-doping in the TiO2 films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO2 films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 ?m and the optical gap of the Hg-doped TiO2 thin films. Hg-doped TiO2 thin films.

  4. 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.

  5. The Influence of Various Deposition Techniques on the Structural and Photoelectrochemical Properties of the thin TiO2 Films.

    Czech Academy of Sciences Publication Activity Database

    Morozová, Magdalena; Kluso?, Petr; Dzik, P.; Veselý, M.; Baudys, M.; Krýsa, J.; Šolcová, Olga

    Prague : KANAG -TISK, 2014 - (Krýsa, J.; Kluso?, P.), s. 14-15 ISBN 978-80-7080-886-3. [Czech-Austrian Workshop: New Trends in Photo and Electro Catalysis /6./. Hnanice (CZ), 02.12.2013-04.12.2013] R&D Projects: GA TA ?R TA01020804 Grant ostatní: GA ?R(CZ) GP104/09/P165; GA ?R(CZ) GAP108/12/2104 Institutional support: RVO:67985858 Keywords : thin films * nanostructured electrode material * TiO2 layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering

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

    International Nuclear Information System (INIS)

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

  7. Influence of annealing temperature on the photoluminescence property of ZnO thin film covered by TiO2 nanoparticles

    International Nuclear Information System (INIS)

    In this work, ZnO thin films covered by TiO2 nanoparticles (labeled as TiO2-ZnO thin films) were prepared by electron beam evaporation. The influence of annealing temperature on the photoluminescence property of the samples was studied. The structures and surface morphologies of the samples were analyzed by X-ray diffraction (XRD) and atomic force microscope, respectively. The photoluminescence was used to investigate the fluorescent properties of the samples. The measurement results show that the ultraviolet emission of ZnO thin films is largely enhanced after they are covered by TiO2 nanoparticles, while the green emission is suppressed. However, when the annealing temperature is relatively high (?500 oC), the intensity of ultraviolet emission drops off and a violet emission peak along with a blue emission peak appears. This is probably connected with the atomic interdiffusion between TiO2 nanoparticles and ZnO thin film. Therefore, selecting a suitable annealing temperature is a key factor for obtaining the most efficient ultraviolet emission from TiO2-ZnO thin films.

  8. 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.

  9. Optical and structural properties of TiO2 and MgF2 thin films by plasma ion-assisted deposition

    International Nuclear Information System (INIS)

    We deposited TiO2 and MgF2 thin films by means of plasma ion-assisted deposition (PIAD) at substrate temperatures (Ts) of ambient and 140 .deg. C, and compared their optical and structural properties with those obtained by means of conventional e-beam evaporation (CE). The results show that TiO2 films deposited by PIAD at Ts = 140 .deg. C have a higher mean refractive index, a smaller inhomogeneous refractive index, a lower extinction coefficient, and smoother surface roughness than the CE TiO2 films. Also, they show an amorphous crystalline phase and transit from tensile stress in the CE films to compressive stress. MgF2 films by PIAD exhibit a larger extinction coefficient, higher optical absorption, a stronger polycrystalline phase, and higher tensile stress than the CE MgF2 films. A TiO2/MgF2 multilayer filter, consisting of the PIAD TiO2 films at Ts = 140 .deg. C and the CE MgF2 films at Ts = 140 .deg. C, has the smallest total stress and does not exhibit any sign of microcracks, while filters with the CE TiO2 films show many microcracks due to high tensile stress. It is found that the PIAD method for TiO2 films combined with substrate heating is very helpful in achieving stable TiO2/MgF2 multilayer optical coatings, due to the dense microstructure, high refractive ind dense microstructure, high refractive index, low extinction coefficient, smooth surface, and compressive stress.

  10. In-situ and ex-situ characterization of TiO2 and Au nanoparticle incorporated TiO2 thin films for optical gas sensing at extreme temperatures

    Science.gov (United States)

    Ohodnicki, Paul R.; Wang, Congjun; Natesakhawat, Sittichai; Baltrus, John P.; Brown, Thomas D.

    2012-03-01

    Sensor technologies that can operate under extreme conditions including high temperatures, high pressures, highly reducing and oxidizing environments, and corrosive gases are needed for process monitoring and control in advanced fossil energy applications. Sensor technologies based on optical waveguide-based techniques are highly attractive for passive, embedded, and remote sensing. A critical enabling technology for optical waveguide sensors is the development of advanced optical thin film coatings which have a desired set of optical properties that change in a rapid, selective, and sensitive manner to a particular quantity of interest. TiO2 and Au nanoparticle incorporated TiO2 nanocomposite thin films were prepared through sol-gel deposition techniques and their respective optical responses to a 4% H2/N2 mixture were investigated in the visible / near-IR range of 400-1000 nm. A tendency for Au nanoparticles to occupy special sites on the TiO2 microstructure, such as grain boundaries, twin boundaries, and triple points is rationalized in terms of basic surface energy arguments. The Au / TiO2 nanocomposite films showed a useful optical response due to a reversible, rapid, and repeatable shift in the localized surface plasma resonance peak of Au nanoparticles at a temperature of 650 °C and 850 °C. In contrast, high temperature exposure of TiO2 films to reducing gases at 850 °C resulted in the growth of abnormally large grains or "hillocks" that protruded from the sample surface and resulted in light scattering and an irreversible decrease in transmission at short wavelengths. The origin of the observed optical response of Au / TiO2 nanocomposite films is discussed in the context of work by prior investigators in the Au / yttria-stabilized Zirconia (YSZ) system and needs for future research in this area is highlighted.

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

    Science.gov (United States)

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

    2014-05-14

    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

  12. 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

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

    Science.gov (United States)

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

    2015-01-01

    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

  14. Determination of the melting threshold of TiO2 thin films processed by excimer laser irradiation

    International Nuclear Information System (INIS)

    Processing surfaces by laser needs an understanding of the mechanisms generated by irradiation. In this work, to gain understanding of the mechanisms occurring during irradiation of TiO2 thin films by means of KrF excimer laser, we have performed infrared time resolved reflectivity measurements. This experimental investigation revealed modifications of the heating/cooling cycle as a function of the fluence (F). These modifications start appearing for a fluence value of about ?0.25 J/cm2 which is associated with the melting threshold of the film. Additionally, we have solved numerically the heat equation of the system with specific boundary conditions. From these calculations, we have established the thermal history of the film during the 25 ns irradiation pulse. The data reveal that a part of the medium liquefies around a fluence of 0.23 J/cm2 in good agreement with the experimental data.

  15. 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.

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

    CERN Document Server

    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

    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...

  17. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    Directory of Open Access Journals (Sweden)

    Hairong Wang

    2014-09-01

    Full Text Available An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 ?m × 350 ?m was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor’s output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10?4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required.

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

    OpenAIRE

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

    2013-01-01

    TiO2 films were deposited on glass substrates with and without O2 plasma etching by using the RF-magnetronsputtering method. We focused on the effect of surface structure on the photoinduced hydrophilic properties of TiO2films, fabricated on different surface conditions according to the presence or absence of the O2 plasma treatmenton glass substrates. The wettability and photoinduced hydrophilic properties of the TiO2 films were investigatedaccording to the changes in water contact angles un...

  19. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

    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.

  1. 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.

  2. 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.

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

    Science.gov (United States)

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

    2015-03-01

    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 8 at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (1 0 1) plane at 8 at.% 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 8 at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398 nm was observed at the 8 at.% 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.

  4. 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.

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

    Science.gov (United States)

    Zuo, J.; Keil, P.; Grundmeier, G.

    2012-07-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Lek Sikong

    2010-08-01

    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.

  7. 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)

    Liana Key Okada, Nakamura; Jorge Moreira, Vaz.

    1173-11-01

    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.

  8. Growth of nanocrystalline TiO2 thin films and crystal anisotropy of anatase phase deposited by direct current reactive magnetron sputtering

    International Nuclear Information System (INIS)

    This work describes the growth and elastic anisotropy of nanocrystalline TiO2 films deposited by direct current reactive magnetron sputtering. The films are nanocrystalline in the gas pressure range 0.4–1.0 Pa even in the absence of substrate bias and substrate heating. It has been observed that gas pressure has a considerable effect on the phase evolution of TiO2 and at a higher pressure, nanocrystalline anatase can be produced with a greater crystallinity and dense surface. X-ray diffraction line profile analysis of anatase TiO2 has been performed and the integral breadth expressions of line broadening due to the domain size and lattice microstrain are combined on the basis of the Williamson–Hall (WH) method. The Miller indices dependence of Young's modulus is estimated on the basis of the Reuss approximation for polycrystalline aggregates. Young's modulus shows strong anisotropy. The anisotropic nature of the elastic medium has been introduced in the classical WH plot under the uniform stress deformation model (USDM) and uniform deformation energy density model (UDEDM). USDM represents the better fit of the experimental data. - Highlights: ? Growth of nanocrystalline TiO2 films prepared by reactive magnetron sputtering. ? Anatase grains grow much faster than rutile grains. ? Near band edge luminescence of TiO2 due to oxygen vacancies. ? Facile X-ray line profile analysis for nanocrystalline thin films. ? Elastic anisotropy causes X-ray diffraction line broadening of anatase TiO2

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

    International Nuclear Information System (INIS)

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

  10. Preparation of high refractive index TiO2 thin film via sol-gel process

    International Nuclear Information System (INIS)

    A simple sol-gel method was applied to prepare high refractive index thin film used in antilaser optical area. The method composed of two steps employing a complete hydrolysis and a restrained polycondensation at low temperature. The morphology of the resulting sol was determined by dynamic light scattering(DLS) techniques and was characterized as anatase by high- resolution transmission electron microscopy(HRTEM). The thin optical films were deposited on K9 glass by a sol-gel spin-coating method. The film shows the presence of nanocrystalline anatase phase by X-ray diffraction(XRD) analysis. The film surface examined by atomic force microscopy(AFM) shows a mean square roughness of 7.5 nm. The transmission spectra of the film were measured using a UV-Vis-NIR spectrometer, and the refractive index, absorption coefficient of the film were calculated by ellipsometer. The refractive index of the films was about 1.91, much larger than other sol-gel films (about 1.6). The average laser induced damage threshold is 16.3 J·cm-2 (3 ns pulse), close to that of amorphous sol-gel films (16.6 J·cm-2 , 3 ns pulse) and much larger than that of physical films (10.8 J·cm-2 , 3 ns pulse). (authors)

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

    International Nuclear Information System (INIS)

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

  12. Sol-gel synthesis, characterization and optical properties of mercury-doped TiO 2 thin films deposited on ITO glass substrates

    Science.gov (United States)

    Mechiakh, R.; Ben Sedrine, N.; Chtourou, R.

    2011-08-01

    The Hg-doped and undoped nano-crystalline TiO 2 films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO 2 were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO 2, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 °C. The average crystallite size of the undoped TiO 2 films was about 8.17 nm and was increased with Hg-doping in the TiO 2 films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO 2 films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 ?m and the optical gap of the Hg-doped TiO 2 thin films.

  13. Phase transition of TiO2 thin films detected by the pulsed laser photoacoustic technique

    Science.gov (United States)

    Pérez-Pacheco, A.; Castañeda-Guzmán, R.; Oliva Montes de Oca, C.; Esparza-García, A.; Pérez Ruiz, S. J.

    2011-03-01

    In this work, we present characterization of titanium oxide thin films by photoacoustic measurements to determine the ablation threshold and phase transitions from amorphous to crystalline states. The important advantages of this method are that it does not require amplification at the detection stage and that it is a non-destructive technique. The correlation analysis of the photoacoustic signals allows us to visualize the ablation threshold and the phase transitions with enhanced sensitivity. This correlation analysis clearly exhibits the changes in the thin-film morphology due to controlled variations of the fluence (energy/area) and the temperature of the surrounding medium. This is particularly important for those cases where the crystalline changes caused by temperature variations need to be monitored. The thin-film samples were prepared by the sputtering technique at room temperature in the amorphous state. The phase transformations were induced by controlled temperature scanning and then corroborated with Raman spectroscopy measurements.

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

    Science.gov (United States)

    Marathe, Sunil D.; Shrivastava, Vinod S.

    2015-02-01

    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.

  15. 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.

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

    Scientific Electronic Library Online (English)

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

    2002-12-01

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

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

    Directory of Open Access Journals (Sweden)

    M. I. B. Bernardi

    2002-12-01

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

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

    Scientific Electronic Library Online (English)

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

    2002-03-01

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

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

    Directory of Open Access Journals (Sweden)

    M. I. B. Bernardi

    2002-03-01

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

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

    Science.gov (United States)

    Behpour, Mohsen; Atouf, Vajiheh

    2012-06-01

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

  1. 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.

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

    Science.gov (United States)

    Niemelä, Janne-Petteri; Karppinen, Maarit

    2015-01-14

    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

  3. 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)

  4. Deposition of nanocrystalline thin TiO2 films for MOS capacitors using Sol-Gel spin method with Pt and Al top electrodes

    Science.gov (United States)

    Rathee, Davinder; Kumar, Mukesh; Arya, Sandeep K.

    2012-10-01

    Nanocrystalline titanium dioxide (TiO2) films were deposited by Sol-Gel spin coating method on well clean P Si substrate. Titanium isoproxide Ti(OC3H7O2)4 (TIP) was used as the Titania precursor. The thickness, composition, and surface morphology of the thin films were characterized using Stylus profilometer, X-ray diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). The crystallite sizes of the TiO2 grains were measured from the typical diffraction peaks and were found to be approximately 23-54 nm. The XRD pattern and Raman spectrum analysis of the deposited film confirmed the polymorphism nature of TiO2 thin films. After annealing at high temperature; the phase transition, improvement in crystallinity, structure and property of the films were being observed. The six Raman peaks were analyzed at 145 cm-1, 199 cm-1, 397 cm-1, 516 cm-1 (doublet) and 637 cm-1 corresponding to active mode of anatase phase. Capacitance-Voltage (C-V) measurement analysis was performed to obtain various devices and process parameters. Metal Oxide Semiconductor (MOS) capacitors with Pt and Al as the top electrode were fabricated to explore electrical characteristics. The refractive index by ellipsometry was found 2.36 and dielectric constant was calculated as 58. In this study, the comparison of the leakage current for TiO2 thin films fabricated by various methods has also been reported.

  5. 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

  6. Electroforming and switching properties of binary-oxide TiO2 thin films for nonvolatile memory applications

    International Nuclear Information System (INIS)

    Unique TiO2 thin films for nonvolatile memory applications were successfully prepared on metal electrodes at various oxygen concentrations by utilizing a conventional rf magnetron sputtering system. All the samples clearly exhibited negative resistance phenomenon and nonvolatile memory switching behavior. In order to investigate the influence of the crystal structure and the cell size on the reversible resistance switching properties, we varied the cell size from 400 to 2500 ?m2, and the stability of the ON/OFF voltage was found to strongly depend on the crystallinity of the oxide materials. This electrically-induced effect, observed in binary-oxide materials at room temperature, hold both the benefit of new materials properties and the promise of applications for high-density nonvolatile memories.

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

    Science.gov (United States)

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

    2005-02-01

    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.

  8. Effect of substrate temperature on the optical and the electrochromic properties of sputtered TiO2 thin films

    International Nuclear Information System (INIS)

    Titanium oxide films (TiO2) were deposited on ITO-coated glass substrates at different substrate temperatures by using an RF reactive magnetron sputtering in an Ar/O2 atmosphere, and their electrochromic properties and stability by repeated coloring and bleaching cycles were investigated for counterelectrode applications. The electrochemical properties of the TiO2 films as counterelectrodes showed weak dependences on the substrate temperature. The optical band gap of the film increased from 3.30 eV to 3.40 eV when the substrate temperature was increased from room temperature to 500 .deg. C. The cyclic durability of the TiO2 films deposited at a substrate temperature of 200 .deg. C was found to be the most stable and was suitable for counterelectrode applications when the films were subjected to 1000 cycles between -2 V and +2 V in a 1-M solution of LiClO4.

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

    International Nuclear Information System (INIS)

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

  10. 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

  11. Internal structure of nanoporous TiO2/polyion thin films prepared by layer-by-layer deposition.

    Science.gov (United States)

    Kniprath, R; Duhm, S; Glowatzki, H; Koch, N; Rogaschewski, S; Rabe, J P; Kirstein, S

    2007-09-11

    The internal structure of porous TiO2 films prepared by electrostatic layer-by-layer deposition was investigated. The films were prepared by alternate dipping of solid substrates into dispersions of TiO2 nanoparticles and polycations, polyanions, or pure buffer solution, respectively. The surface charge of the amphoteric TiO2 particles was controlled by the pH of the aqueous dispersions. The morphology of the film surface was investigated by means of scanning electron microscopy. It was found that the surface roughness strongly depends on the polymeric material used for the deposition process but is independent of the ionic strength of the solution or the molecular weight of the polyions. The samples with rough surfaces feature strong light scattering. The porosity and internal structure of the TiO2/polyelectrolyte films were investigated by adsorption/desorption of dye molecules. A crude estimate yields an internal surface that is up to 160 times the plane surface of the substrate for a film thickness of 1 microm. The composition of the films was investigated by X-ray photoelectron spectroscopy (XPS). Detection of the XPS signal after each deposition step of the first three dipping cycles shows a significant increase of the relative surface coverage of Ti after the TiO2 deposition step and of PSS after the PSS deposition step. For later dipping cycles, such an increase was also detectable but less prominent. PMID:17696454

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

    OpenAIRE

    Tallarida, Massimo; Das, Chittaranjan; Schmeisser, Dieter

    2014-01-01

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

  13. Molecular Interaction of Thin Film Photosensitive Organic Dyes on TiO2 Surfaces

    OpenAIRE

    Yu, Shun

    2011-01-01

    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...

  14. 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)

  15. Room-temperature ferromagnetic properties in Mn-doped rutile TiO2-? thin films

    International Nuclear Information System (INIS)

    Room-temperature ferromagnetic properties of Mn-doped reduced titanium dioxide (Ti1-xMnxO2-?) thin films with rutile structure synthesized by a sol-gel method have been detected for a limited range of Mn composition (x). The Ti1-xMnxO2-? films were found to be p-type semiconducting with hole concentration near 1019cm-3. The observed ferromagnetism in the Ti1-xMnxO2-? films is not related to the hole concentration but related to x. The room-temperature ferromagnetism is attributable to magnetic polaron formed by trapped electron in oxygen vacancy and magnetic ions around it. Thus, the existence of oxygen vacancies is necessary for the room-temperature ferromagnetism

  16. 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.

  17. Effect of pulsed bias on TiO2 thin films prepared on silicon by arc ion plating and simulation of pulsed plasma sheath dynamics

    International Nuclear Information System (INIS)

    Dielectric TiO2 thin films were fabricated on p-(100) Si substrates by arc ion plating. A pulsed substrate bias ranging from 0 V to ? 900 V was applied to investigate the effect of pulsed bias on phase structure and growth of the films. Phase, microstructure, and growth morphology of TiO2 films prepared at different bias voltages were evaluated with grazing incident x-ray diffraction and atomic force microscopy (AFM). The results show that pulsed bias exerts an evident influence on phase structure and growth morphology. High substrate bias facilitates the formation of rutile phase, a (220) preferred orientation is observed in TiO2 films obtained at ? 900 V. AFM images show that pulsed substrate bias exerts a strong influence on the growth of TiO2 films. With increasing bias voltage, the film is initially composed of tiny surface islands separated by shallow boundaries, then of large and spiky surface islands isolated by deep boundaries. Correspondingly, surface roughness increases from 1.1 nm at 0 V to 3.8 nm at ? 900 V. To explain the phenomena observed in this study, pulsed plasma sheath model was used to simulate the ion sheath dynamics. By analyzing experimental and simulated results, it can be concluded that film growth and property relate close to ion density and energy in the sheath, which is dominantly governed by negative substrate bias.

  18. Nano crystalline TiO2 thin films as negative electrodes for lithium ion batteries.

    Science.gov (United States)

    Aslan, Serdar; Guler, Mehmet Oguz; Cevher, Ozgur; Akbulut, Hatem

    2012-12-01

    In this study, rutile (tetragonal, P42/mnm), anatase (tetragonal, I41/amd) polymorphs of titanium dioxide films were synthesized successfully magnetron sputtering of titanium films on stainless steel substrates followed by in situ direct current plasma oxidation. The as-prepared titanium dioxide thin films were oxidized at 75 W, 100 W and 125 W plasma powers in order to optimize the system with best electrochemical performance. The mean grain sizes of the deposited films were found to be in the range of 14.2-12.9 nm as revealed by the scanning electron microscopy and X-ray diffractometer studies. The electrochemical studies were performed with pure metallic lithium foil cathode with the best performing nano structured titanium dioxide as anode. The specific capacity of the nanocrystalline titanium dioxide films oxidized at 125 W direct current was 207 mA h g(-1) even after 20 cycles in the 0.02-2 V region, indicating excellent cycling stability and reversibility. PMID:23447985

  19. 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

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

    Science.gov (United States)

    Kim, Dong-Joo; Kim, Kyo-Seon

    2010-05-01

    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

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

    OpenAIRE

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

    2012-01-01

    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...

  2. 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)

  3. 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

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

    OpenAIRE

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

    2011-01-01

    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 influen...

  5. 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.

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

    Directory of Open Access Journals (Sweden)

    Anouar Hajjaji

    2014-06-01

    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.

  7. Investigation of reactive HiPIMS + MF sputtering of TiO2 crystalline thin films.

    Czech Academy of Sciences Publication Activity Database

    Olejní?ek, Ji?í; Hubi?ka, Zden?k; Kment, Št?pán; ?ada, Martin; Kšírová, Petra; Adámek, Petr; Gregora, Ivan

    2013-01-01

    Ro?. 232, OCT (2013), s. 376-383. ISSN 0257-8972 R&D Projects: GA MŠk LH12045; GA ?R GAP108/12/1941; GA MŠk LD12002; GA ?R GAP108/12/2104; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : HiPIMS * mid-frequency * ion velocity distribution function * TiO 2 * rutile Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.199, year: 2013 http://www.sciencedirect.com/science/article/pii/S0257897213004829

  8. 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.)

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

    International Nuclear Information System (INIS)

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

  10. 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.

  11. Structural and morphological properties of TiO2thin films prepared by spray pyrolysis

    Directory of Open Access Journals (Sweden)

    N. Castillo

    2004-01-01

    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.

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

    Science.gov (United States)

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

    2014-12-10

    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

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

    Science.gov (United States)

    Dam Le, Duy; Dung Dang, Thi My; Thang Chau, Vinh; Chien Dang, Mau

    2010-03-01

    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.

  14. 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

  15. 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

  16. Corrosion behavior of TiO2–NiO nanocomposite thin films on AISI 316L stainless steel prepared by sol–gel method

    International Nuclear Information System (INIS)

    TiO2–NiO nanocomposite thin films were deposited on the 316L stainless steel using sol–gel method by a dip coating technique. Different techniques such as differential thermal analysis, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and scanning probe microscopy were carried out in order to characterize the structure of the coatings. The corrosion resistance of the coatings was evaluated by using Tafel polarization and electrochemical impedance spectroscopy tests of uncoated and coated specimens in a 3.5% NaCl solution at room temperature. It was found that to obtain desirable structure in coatings, the coatings should be calcined at 600 °C for one and half hour. NiTiO3, anatase and rutile were the phases obtained in different calcination conditions in air atmosphere. The results of corrosion tests indicated that with increasing the dipping times from 2 to 4, the corrosion current density first decreases but when increasing the dipping times to 6, it increases. Also the corrosion current density decreased from 186.7 nA.cm?2 (uncoated steel) to 34.21 nA.cm?2 (80%TiO2–20%NiO) and corrosion potential increased from ? 150.2 mV (uncoated steel) to ? 107.3 mV (67%TiO2–33%NiO). - Highlights: ? TiO2–NiO thin films were deposited on the 316L stainless steel using sol–gel method. ? Different compositions, anncompositions, annealing times and temperatures resulted in various phases. ? Films having different compositions showed various surface morphologies. ? Films having a composition of 80%TiO2–20%NiO showed a good corrosion protection.

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

    Science.gov (United States)

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

    2015-02-01

    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.

  18. Excellent resistive switching property and physical mechanism of amorphous TiO2 thin films fabricated by a low-temperature photochemical solution deposition method

    Science.gov (United States)

    Zou, Lilan; Hu, Wei; Xie, Wei; Chen, Ruqi; Qin, Ni; Li, Baojun; Bao, Dinghua

    2014-08-01

    High-performance resistive switching Pt/TiO2/Pt memory cells were fabricated. The amorphous TiO2 active layer was prepared by using a low-temperature photochemical solution deposition method-a simple preparation process combining first chemical solution deposition of the TiO2 film layer and subsequent ultraviolet (UV) irradiation treatment. The obtained Pt/TiO2/Pt memory cells exhibited excellent resistive switching parameters, such as centralized distribution of set and reset voltages, stable current values at high and low resistance states, and long retention time. The conductive mechanisms of high resistance state and low resistance state were Schottky emission and Ohmic conduction, respectively. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy characterization of the TiO2 thin films indicated that the UV irradiation treatment can lead to decomposition of the residual organics and the formation of enhanced metal-oxide bonds in the thin films. On the basis of the analysis of current-voltage characteristics and the temperature dependence of resistance, we explained the resistive switching phenomenon for Pt/TiO2/Pt devices by using the model of formation/rupture of conductive filaments. Our study also suggested that the simple photochemical solution deposition method can be used for preparing some other oxide thin films with good resistive switching properties at low processing temperature which is promising to be extended to flexible resistive switching devices.

  19. 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.

  20. 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.

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

    International Nuclear Information System (INIS)

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

  2. Raman spectroscopy of dip-coated and spin-coated sol-gel TiO2 thin films on different types of glass substrates.

    Czech Academy of Sciences Publication Activity Database

    Kment, Š.; Gregora, Ivan; Kmentová, Hana; Novotná, P.; Hubi?ka, Zden?k; Krýsa, J.; Sajdl, P.; Dejneka, Alexandr; Brunclíková, M.; Jastrabík, Lubomír; Hrabovský, M.

    2012-01-01

    Ro?. 63, ?. 3 (2012), s. 294-306. ISSN 0928-0707 R&D Projects: GA ?R GAP108/12/1941; GA ?R GAP108/12/2104; GA TA ?R TA01010517 Institutional support: RVO:68378271 ; RVO:67985858 Keywords : TiO 2 thin films * Raman mapping * sol-gel * dip-coating * spin-coating * glass substrate Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.660, year: 2012

  3. 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.

  4. 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)

    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

    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.

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

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

    2014-08-01

    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.

  7. Comparative photothermal study of reactive low-voltage ion-plated andelectron-beam-evaporated TiO(2) thin films.

    Science.gov (United States)

    Wu, Z L; Bange, K

    1994-12-01

    The thickness-dependent optical and thermal properties and the corresponding damage thresholds have been investigated by means of various photothermal techniques on titanium dioxide thin films prepared by the conventional techniques of reactive electron-beam evaporation and reactive low-voltage ion plating (RLVIP). Compared with the reactive-electron-beam-evaporated samples, the RLVIP films exhibit a higher absorption, lower damage threshold, better thermal conductivity, lower defect density, and an almost perfect stability under Ar(+)-laser irradiation. These results are correlated with data from a multimethod approach, and a mechanism is proposed to explain the low damage threshold for the RLVIP TiO(2) films. PMID:20963004

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

    Scientific Electronic Library Online (English)

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

    2014-02-01

    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.

  9. Preparation of TiO2 and Al2O3 thin films by ion-beam induced chemical vapour deposition

    International Nuclear Information System (INIS)

    In this paper a new method for the preparation of thin film oxides is presented. It consists of a combination of CVD and IBAD techniques: a flow of a volatile metal precursor is directed on the surface of a substrate while it is bombarded with oxygen ions. This induces the decomposition of the precursors and the formation of the corresponding oxide. Thin films of Al2O3 and TiO3 have been prepared by this method using trimethyl aluminium and titanium tetraetoxide as volatile precursors. The kinetics of growth and the carbon content of the films have been monitored by XPS. A first characterization by SEM/TEM has shown that the films are very compact and homogeneous. The refractive index of the TiO2 films determined by uv-vis spectroscopy have been calculated to be between 2.3 and 2.7, depending on the film. (author)

  10. Damage performance of TiO 2 /SiO 2 thin film components induced by a long-pulsed laser

    Science.gov (United States)

    Wang, Bin; Dai, Gang; Zhang, Hongchao; Ni, Xiaowu; Shen, Zhonghua; Lu, Jian

    2011-09-01

    In order to study the long-pulsed laser induced damage performance of optical thin films, damage experiments of TiO2/SiO2 films irradiated by a laser with 1 ms pulse duration and 1064 nm wavelength are performed. In the experiments, the damage threshold of the thin films is measured. The damages are observed to occur in isolated spots, which enlighten the inducement of the defects and impurities originated in the films. The threshold goes down when the laser spot size decreases. But there exists a minimum threshold, which cannot be further reduced by decreasing the laser spot size. Optical microscopy reveals a cone-shaped cavity in the film substrate. Changes of the damaged sizes in film components with laser fluence are also investigated. The results show that the damage efficiency increases with the laser fluence before the shielding effects start to act.

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

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • C-TiO2 thin films were successfully synthesized by modified sol–gel method based on the self-assembly technique. • Tween 80, one kind of hydrocarbon surfactants, was used as template and carbon precursor. • A thorough material characterization was performed to determine the effect of calcination time on the structural and optical properties of the synthesized catalyst films. - Abstract: 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 C-O-Ti 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

  12. Significant enhancement of yellow-green light emission of TiO2 thin films using Au localized surface plasmons: effect of dielectric MgO spacer layer thickness.

    Science.gov (United States)

    Zhang, Cen; Liu, Weizhen; Xu, Haiyang; Ma, Jiangang; Liu, Yichun

    2014-05-01

    TiO2/MgO/Au composite thin films with different MgO spacer layer thicknesses (0-41 nm) were fabricated on c-sapphire substrates by sputtering and pulsed laser deposition. Through optimizing the thickness of MgO spacer layer, which can effectively prevent nonradiative Förster resonant energy transfer and charge transfer between Au and TiO2, defect-related yellow-green light emission of TiO2 thin film was greatly enhanced - 12 times. The enhancement mechanism is attributed to the efficient increase of luminescence efficiency of deep levels in TiO2 induced by resonant coupling between localized surface plasmons in Au nanoparticles and electron-hole pairs in defect-related levels of TiO2. PMID:24734627

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

    Directory of Open Access Journals (Sweden)

    H. Tiznado

    2012-01-01

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

  14. Photocatalytic properties of different TiO2 thin films of various porosity and titania loading.

    Czech Academy of Sciences Publication Activity Database

    Zita, J.; Krýsa, J.; ?ernigoj, U.; Lavren?i?-Štangar, U.; Jirkovský, Jaromír; Rathouský, Ji?í

    2011-01-01

    Ro?. 161, ?. 1 (2011), s. 29-34. ISSN 0920-5861 R&D Projects: GA MŠk 1M0577; GA ?R GA104/08/0435 Institutional research plan: CEZ:AV0Z40400503 Keywords : sol-gel * titanium dioxide film * porosity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.407, year: 2011

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

    International Nuclear Information System (INIS)

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

  16. TiO 2 nanotube, nanowire, and rhomboid-shaped particle thin films fixed on a titanium metal plate

    Science.gov (United States)

    Inoue, Yuko; Noda, Iwao; Torikai, Toshio; Watari, Takanori; Hotokebuchi, Takao; Yada, Mitsunori

    2010-01-01

    Titanium dioxide thin films having various nanostructures could be formed by various treatments on sodium titanate nanotube thin films approximately 5 ?m thick fixed on titanium metal plates. Using an aqueous solution with a lower hydrochloric acid concentration (0.01 mol/L) and a higher reaction temperature (90 °C) than those previously employed, we obtained a hydrogen titanate nanotube thin film fixed onto a titanium metal plate by H + ion-exchange treatment of the sodium titanate nanotube thin film. Calcination of hydrogen titanate nanotube thin films yielded porous thin films consisting of anatase nanotubes, anatase nanowires, and anatase nanoparticles grown directly from the titanium metal plate. H + ion-exchange treatment of sodium titanate nanotube thin films at 140 °C resulted in porous thin films consisting of rhomboid-shaped anatase nanoparticles.

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Drera, Giovanni

    2012-01-01

    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...

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

    Science.gov (United States)

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

    2014-08-13

    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

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

    International Nuclear Information System (INIS)

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

  1. A simple electrophoretic deposition method to prepare TiO2-B nanoribbon thin films for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    This paper describes a simple method utilizing electrophoretic deposition (EPD) to quickly synthesize hydrogen titanate nanoribbon films. The subsequent heating of the hydrogen titanate nanoribbon films causes the dehydration of interlayered OH groups, thereby leading to TiO2-B nanoribbon films. Thick, uniform TiO2-B nanoribbon films were obtained from prepared alkali suspensions. The crystal structure of the hydrogen titanate and TiO2-B nanoribbon films obtained from EPD underwent analysis by X-ray diffraction and high-resolution transmission electron microscope. EPD controlled the thickness of TiO2-B nanoribbons films. TiO2-B-coated fluorine-doped tin oxide films were dye-sensitized with N3 and used as a photoanode in an electrochemical solar cell. The solar cell yielded conversion efficiencies of 0.87% for an incident solar energy of 100 mW/cm2.

  2. Microstructure and optical dispersion characterization of nanocomposite sol-gel TiO2-SiO2 thin films with different compositions.

    Science.gov (United States)

    Kermadi, S; Agoudjil, N; Sali, S; Zougar, L; Boumaour, M; Broch, L; En Naciri, A; Placido, F

    2015-06-15

    Nanocomposite TiO2-SiO2 thin films with different compositions (from 0 to 100mol% TiO2) were deposited by sol-gel dip-coating method on silicon substrate. Crystal structure, chemical bonding configuration, composition and morphology evolutions with composition were followed by Raman scattering, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and scanning electron microscopy respectively. The refractive index and the extinction coefficient were derived in a broad band wavelength (250-900nm) from spectroscopic ellipsometry data with high accuracy and correlated with composition and microstructure. Results showed an anatase structure for 100% TiO2 with a grain size in 6-10nm range. Whereas, the inclusion of SiO2 enlarges the optical band gap and suppresses the grain growth up to 4nm in size. High TiO2 dispersion in SiO2 matrix was observed for all mixed materials. The refractive index (at ?=600nm) increases linearly with composition from 1.48 (in 100% SiO2) to 2.22 (in 100% TiO2) leading to lower dense material, its dispersion being discussed in terms of the Wemple-DiDomenico single oscillator model. Hence, the optical parameters, such optical dispersion energies E0 and Ed, the average oscillators, strength S0 and wavelength ?0 and the ratio of the carrier concentration to the effective mass N/m(?) have been derived. The analysis revealed a strong dependence on composition and structure. The optical response was also investigated in term of complex optical conductivity (?) and both volume and surface energy loss functions (VELF and SELF). PMID:25770938

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

    Science.gov (United States)

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

    2014-03-01

    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.

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

    International Nuclear Information System (INIS)

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

  5. 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.

  6. 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)

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

    2015-02-01

    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.

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

    Scientific Electronic Library Online (English)

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

    2012-12-01

    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.

  8. Novel hydrophobic/hydrophilic patterning process by photocatalytic Ag nucleation on TiO2 thin film and electroless Cu deposition

    International Nuclear Information System (INIS)

    A hydrophobic/super-hydrophilic pattern was prepared on a TiO2 thin film by a new fabrication process. The process consists of five key steps: (1) photocatalytic reduction of Ag+ to Ag (nucleation), (2) electroless Cu deposition, (3) oxidation of Cu to CuO, (4) deposition of a self-assembled monolayer (SAM), and (5) photocatalytic decomposition of selected areas of the SAM. A hydrophobic/super-hydrophilic pattern with 500-?m2 hydrophilic areas was obtained in this process. It is particularly noteworthy that a UV irradiation time of only 1 s was sufficient for the nucleation step in the patterning process

  9. The cooperation effect of mixed PEGs with different molecular weights on the morphology of TiO2 porous thin films

    International Nuclear Information System (INIS)

    We synthesized TiO2 porous thin films with well-shaped pores and uniform pore size by utilizing the cooperation effect of mixed PEGs with different molecular weights. The pore sizes were about 190 nm and 220 nm for single PEG and double PEGs, respectively, while in the case of triple PEGs, the pore size ranged from about 190 nm to 500 nm. The wall thickness was affected by the difference in chain length of mixed PEGs and a thicker wall produced thermally stable pores. The optimal size distribution and shape of pores could be obtained by using two proper PEGs.

  10. 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.

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

    Science.gov (United States)

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

    2013-12-01

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

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

    Science.gov (United States)

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

    2014-11-28

    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

  13. Photocatalytic activity of TiO2 thin films doped with nitrogen using a cathodic magnetron plasma treatment

    International Nuclear Information System (INIS)

    TiO2 films are treated using a magnetron nitrogen-plasma apparatus that can generate high density plasma to realize nitrogen-doping. The films are treated for 5 min with nitrogen plasma at a discharge power from 30 to 100 W by a radio frequency generator operating at 13.56 MHz. The plasma treated films show visible light absorption in the range of around 400-500 nm. Light absorption above approximately 500 nm is also observed in the film plasma treated at a high discharge power. It is confirmed from N1s and Ti2p X-ray photoelectron spectra of the films that Ti-N bonds and oxygen vacancies are formed. Visible light activity of photocatalysis in the film increases with increasing discharge power and then decreases. Such an increase and decrease in the visible light activity are due to the formation of Ti-N bonds and oxygen vacancies, respectively. The visible light activity is improved with the optimum plasma treatment

  14. Synthesis of uniformly dispersed anatase nanoparticles inside mesoporous silica thin films via controlled breakup and crystallization of amorphous TiO2 deposited using atomic layer deposition

    Science.gov (United States)

    Sree, Sreeprasanth Pulinthanathu; Dendooven, Jolien; Masschaele, Kasper; Hamed, Heidari M.; Deng, Shaoren; Bals, Sara; Detavernier, Christophe; Martens, Johan A.

    2013-05-01

    Amorphous titanium dioxide was introduced into the pores of mesoporous silica thin films with 75% porosity and 12 nm average pore diameter via Atomic Layer Deposition (ALD) using alternating pulses of tetrakis(dimethylamino)titanium and water. Calcination provoked fragmentation of the deposited amorphous TiO2 phase and its crystallization into anatase nanoparticles inside the nanoporous film. The narrow particle size distribution of 4 +/- 2 nm and the uniform dispersion of the particles over the mesoporous silica support were uniquely revealed using electron tomography. These anatase nanoparticle bearing films showed photocatalytic activity in methylene blue degradation. This new synthesis procedure of the anatase nanophase in mesoporous silica films using ALD is a convenient fabrication method of photocatalytic coatings amenable to application on very small as well as very large surfaces.

  15. 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

  16. 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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  19. Nuclear transmutation doping of photocatalytic TiO2 film coatings with transition 3D metals

    International Nuclear Information System (INIS)

    Schema of nuclear transmutation doping TiO2 thin films for photocatalytic effect shift in to visible light region is proposed. Atoms, the products of heat-neutron irradiation process, concentration in TiO2 films calculation program was created and results are shown. Optimal irradiation time period determinated

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

    OpenAIRE

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

    2004-01-01

    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...

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

    Directory of Open Access Journals (Sweden)

    The-Vinh Nguyen

    2009-01-01

    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.

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

    Scientific Electronic Library Online (English)

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

    2004-12-01

    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

  3. Modeling the electrical transport in epitaxial undoped and Ni-, Cr-, and W-doped TiO2 anatase thin films

    Science.gov (United States)

    Kneiß, Max; Jenderka, Marcus; Brachwitz, Kerstin; Lorenz, Michael; Grundmann, Marius

    2014-08-01

    Electrical transport in undoped and Ni-, Cr-, and W-doped TiO2 thin films on SrTiO3(001) is modelled either with the sum of two thermally activated processes with exponential temperature dependence of conductivity, or with the sum of three-dimensional Mott variable-range hopping (VRH) and an activated process with low activation energy. The latter is interpreted for both models as small polaron hopping (chi-square values, the double activated model is superior for data of higher ordered films grown at 540 and 460 °C. For lower growth temperature, VRH plus activated conductivity fits partly better. For all dopants, n-type conductivity is observed.

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    Ann-Louise Anderson

    2014-12-01

    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.

  6. Effects of Co doping on structure and optical properties of TiO2 thin films prepared by sol–gel method

    International Nuclear Information System (INIS)

    Co-doped TiO2 thin films were synthesized on quartz substrates by sol–gel method. Atomic force microscopy results indicate that the surfaces of the Ti1?xCoxO2 (0 ? x ? 0.10) films become smooth and compact with increasing Co content. X-ray diffraction results show that all the films are rutile phase structure and Co doping leads to lattice contraction. X-ray photoelectron spectroscopy results reveal that the predominant oxidation state of Co is divalent. Peak positions of Raman-active modes (B2g, A1g and Eg) shift to lower frequency with increasing Co content. The refractive index n at 670 nm from transmittance spectra increases with increasing Co content. The OBG varies between 3.10 and 3.26 eV. Note that optical band gap (OBG) first increases and then decreases with increasing Co content, reaching its maximum value when x is 0.03. These results suggest that the increasing mechanism of OBG is related to the decrease of grain size, compressive stress, and reduction of rutile TiO2, and the decreasing mechanism of OBG is involved with defect and impurity. The competition of the two mechanisms leads to the strange change of OBG. - Highlights: ? Ti1?xCoxO2 thin films (0 ? x ? 0.1) were fabricated by the sol–gel method. ? Increase in Co contents results in Raman shifts to lower frequencies. ? The packing density increases with increincreases with increasing Co doping. ? The optical band gap increases and then decreases with the increasing Co content. ? The optical band gap varies between 3.1 and 3.26 eV.

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

    International Nuclear Information System (INIS)

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

  8. Tuning the Photocatalytic Activity of Anatase TiO2 Thin Films by Modifying the Preferred <001> Grain Orientation with Reactive DC Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    B. Stefanov

    2014-08-01

    Full Text Available Anatase TiO2 thin films were deposited by DC reactive magnetron sputtering on glass substrates at 20 mTorr pressure in a flow of an Ar and O2 gas mixture. The O2 partial pressure (PO2 was varied from 0.65 mTorr to 1.3 mTorr to obtain two sets of films with different stoichiometry. The structure and morphology of the films were characterized by secondary electron microscopy, atomic force microscopy, and grazing-angle X-ray diffraction complemented by Rietveld refinement. The as-deposited films were amorphous. Post-annealing in air for 1 h at 500 °C resulted in polycrystalline anatase film structures with mean grain size of 24.2 nm (PO2 = 0.65 mTorr and 22.1 nm (PO2 = 1.3 mTorr, respectively. The films sputtered at higher O2 pressure showed a preferential orientation in the <001> direction, which was associated with particle surfaces exposing highly reactive {001} facets. Films sputtered at lower O2 pressure exhibited no, or very little, preferential grain orientation, and were associated with random distribution of particles exposing mainly the thermodynamically favorable {101} surfaces. Photocatalytic degradation measurements using methylene blue dye showed that <001> oriented films exhibited approximately 30% higher reactivity. The measured intensity dependence of the degradation rate revealed that the UV-independent rate constant was 64% higher for the <001> oriented film compared to randomly oriented films. The reaction order was also found to be higher for <001> films compared to randomly oriented films, suggesting that the <001> oriented film exposes more reactive surface sites.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    Science.gov (United States)

    Zhu, Ming; Zhu, Gangbei; Weng, Yuxiang

    2013-05-01

    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

  11. Effect of dehydration rate on non-hydrolytic TiO2 thin film processing: Structure, optical and photocatalytic performance studies

    International Nuclear Information System (INIS)

    Highlights: ? Clear transparent TiO2 thin film prepared using non aqua sol-gel processing. ? The complexing agents plays significant role in the rate of dehydration due to hydrolysis. ? Faster dehydration significantly affects visible light transmittance and other properties. ? Diethanoalamine plays significant role in the crystallization and phase transformation. - Abstract: The influence of complexing agent diethanolamine (DEA) on the rate of dehydration due to hydrolysis in titania thin films prepared by non-aqua sol-gel process was investigated. The formation of complex with titanium precursor controls the rate of hydrolysis over wide range of temperature. The rate of hydrolysis with respect to complex formation and firing temperate was studied by using thermogravimetry and differential thermal analysis (TG-DTA). The role of complexing agent in the crystallization of anatase and phase transformation to rutile was studied by X-ray diffraction (XRD). Effect of complexing agent on the optical transmittance in the visible range was monitored by ultraviolet-visible absorption spectroscopy. Photocatalytic performance of the titania films was measured using methylene blue (MB) as the model contaminant. Mechanical characteristics such as hardness and adhesion of the film were rated by using scratch tests as per ASTM standards.

  12. 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.

  13. Self-sterilization using silicone catheters coated with Ag and TiO2 nanocomposite thin film.

    Science.gov (United States)

    Yao, Yanyan; Ohko, Yoshihisa; Sekiguchi, Yuki; Fujishima, Akira; Kubota, Yoshinobu

    2008-05-01

    Ag/titanium dioxide (TiO(2))-coated silicon catheters were easily fabricated with Ag nanoparticles deposition on both the inside wall and the outside wall of TiO(2)-coated catheters by TiO(2) photocatalysis. This is an application of the silicon catheters coated with TiO(2), which possess a self-sterilizing and self-cleaning property combining with UV light illumination (Ohko et al., J Biomed Mater Res: Appl Biomater 2001;58:97). Ag/TiO(2)-coated silicon catheters exhibited a strong bactericidal effect even in the dark. When the 2-5 x 10(5) of colony-forming units of Escherichia coli, Pseudomonas aeruginosa, or Staphylococcus aureus were respectively applied to the surface of the Ag/TiO(2) catheters, which were loaded with approximately 15 nmol cm(-2) of Ag, 99% effective sterilization occurred in a very short time: 20 min for E. coli, 60 min for P. aeruginosa, and 90 min for S. aureus. Additionally, the Ag/TiO(2)-coated catheters possessed a strong self-cleaning property. Using UV illumination, the photocatalytic decomposition rate of methylene blue dye representing the self-cleaning capability, on an Ag/TiO(2) catheter which was loaded with 2 nmol cm(-2) of Ag, was approximately 1.2 times higher (at maximum) than that on TiO(2) coating alone. Furthermore, the Ag nanoparticles can be pre-eminently and uniformly deposited onto the TiO(2) coating, and the amount of Ag was easily controllable from a few nanomoles per square centimeter to approximately 70 nmol cm(-2) by changing the UV illumination time for TiO(2) photocatalysis. This type of catheter shows a great promise in lowering the incidence of catheter-related bacterial infections. PMID:18098205

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    F. Arefi-Khonsari

    2011-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Claudio Frausto-Reyes

    2006-01-01

    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.

  17. 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

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

    Science.gov (United States)

    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

    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%.

  19. Growth of Au -TiO2 nanocomposite thin films by a dual-laser, dual-target system

    Science.gov (United States)

    György, E.; Sauthier, G.; Figueras, A.; Giannoudakos, A.; Kompitsas, M.; Mihailescu, I. N.

    2006-12-01

    Nanocomposite thin films formed by gold nanoparticles embedded in a titanium dioxide matrix have been synthesized by pulsed laser deposition. Two synchronized laser sources, an ArF* excimer (? =193nm, ?FWHM˜12ns) laser and a frequency tripled Nd:yttrium aluminium garnet (? =355nm, ?FWHM˜10ns) laser, were used for the simultaneous ablation of the titanium dioxide and gold targets. The optical absorption characteristics of the obtained nanocomposites were investigated as a function of laser parameters used for the ablation of the gold target. The obtained results proved the possibility of tuning the optical properties of gold-titanium dioxide nanocomposites with the proper choice of laser irradiation parameters. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of gold enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

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

    International Nuclear Information System (INIS)

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

  1. TiO2 thin and thick films grown on Si/glass by sputtering of titanium targets in an RF inductively coupled plasma

    Science.gov (United States)

    Valencia-Alvarado, R.; de la Piedad-Beneitez, A.; López-Callejas, R.; Mercado-Cabrera, A.; Peña-Eguiluz, R.; Muñoz-Castro, A. E.; Rodríguez-Méndez, B. G.; de la Rosa-Vázquez, J. M.

    2015-03-01

    TiO2 thin and thick films were deposited on silicon/glass substrates using RF inductive plasma in continuous wave. The films thickness, as well as phases control, is achieved with a gradual increase in temperature substrates varying supplied RF power or working gas pressure besides deposition time as well. The deposition conditions were: argon 80%/oxygen 20% carefully calibrated mixture of 2 to 7×10?2 mbar as working gas pressure range. Deposition time 0.5 to 5 hours, 500 or 600 W RF power at 13.56 MHz frequency and 242-345 °C substrates temperature range. The titanium dioxide deposited on the substrates is grown by sputtering of a titanium target negatively polarized at 3-5 kV DC situated 14 mm in front of such substrates. The plasma reactor is a simple Pyrex-like glass cylindrical vessel of 50 cm long and 20 cm in diameter. Using the before describe plasma parameters we obtained films only anatase and both anatase/rutile phases with stoichiometric different. The films were characterized by X-ray photoelectron spectroscopy (XPS), stylus profilometer, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy.

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

    Science.gov (United States)

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

    2014-10-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-21

    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.

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

    OpenAIRE

    Kaspar, T.; Ney, A.; Mangham, A.; Heald, S.; Joly, Yves; Ney, V.; Wilhelm, Fabrice; Rogalev, Andrei; Yakou, F.; Chambers, S.

    2012-01-01

    Homoepitaxial thin films of Fe:TiO2 and (Fe,N):TiO2 were deposited on rutile(110) by molecular beam epitaxy. X-ray absorption near edge spectroscopy (XANES) spectra were collected at the Ti L-edge, Fe L-edge, Ti K-edge, O K-edge, and N K-edge. No evidence of structural disorder associated with a high concentration of oxygen vacancies is observed. Substitution of Fe for Ti could be inferred, and secondary phases such as Fe2O3, Fe3O4, and FeTiO3 can be ruled out. The similarity of the N K-edge ...

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  7. 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

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

    OpenAIRE

    Arefi-khonsari, F.; Meshkini, F.; Jafari, R.; Mortaheb, H.; Pulpytel, J.; Smith, W.; Fakhouri, H.; Zolfaghari, A.

    2011-01-01

    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 co...

  9. Optical properties of nanostructured TiO2 thin films and their application as antireflection coatings on infrared detectors.

    Science.gov (United States)

    Jayasinghe, R C; Perera, A G U; Zhu, H; Zhao, Y

    2012-10-15

    Oblique-angle deposited titanium dioxide (TiO(2)) nanorods have attracted much attention as good antireflection (AR) coating material due to their low n profile. Therefore, it is necessary to better understand the optical properties of these nanorods. TiO(2) nanorods grown on glass and Si substrates were characterized in the visible (0.4-0.8 ?m) and infrared (2-12 ?m) regions to extract their complex n profiles empirically. Application of these nanorods in multilayer AR coatings on infrared detectors is also discussed. Optimization of graded index profile of these AR coatings in the broad infrared region (2-12 ?m) even at oblique angles of incidence is discussed. The effective coupling between the incoming light and multiple nanorod layers for reducing the reflection is obtained by optimizing the effect from Fabry-Perot oscillations. An optimized five-layer AR coating on GaN shows the reflectance less than 3.3% for normal incidence and 10.5% at 60° across the whole 2-8 ?m spectral range. PMID:23073444

  10. Self-sterilizing and self-cleaning of silicone catheters coated with TiO(2) photocatalyst thin films: a preclinical work.

    Science.gov (United States)

    Ohko, Y; Utsumi, Y; Niwa, C; Tatsuma, T; Kobayakawa, K; Satoh, Y; Kubota, Y; Fujishima, A

    2001-01-01

    TiO(2) photocatalysts were successfully coated on silicone catheters or medical tubes by pretreatment of the silicone surface with a sulfuric acid solution (5 M) for 3 h. The TiO(2) film adhered to the silicone substrate strongly against tensile and bending stresses. On the TiO(2)-coated silicone-catheters under UV illumination, both the bleaching of methylene blue dye and the photocatalytic bactericidal effect on Escherichia coli (E. coli) cells were confirmed. Thus, this type of catheter can be sterilized and cleaned simply by irradiation with low-intensity UV light and can, therefore, be useful in the protection from catheter-related bacterial infections. PMID:11153004

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-23

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

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

    Science.gov (United States)

    Kaspar, T. C.; Ney, A.; Mangham, A. N.; Heald, S. M.; Joly, Y.; Ney, V.; Wilhelm, F.; Rogalev, A.; Yakou, F.; Chambers, S. A.

    2012-07-01

    Homoepitaxial thin films of Fe:TiO2 and (Fe,N):TiO2 were deposited on rutile(110) by molecular beam epitaxy. X-ray absorption near edge spectroscopy (XANES) spectra were collected at the Ti L-edge, Fe L-edge, Ti K-edge, O K-edge, and N K-edge. No evidence of structural disorder associated with a high concentration of oxygen vacancies is observed. Substitution of Fe for Ti could be inferred, and secondary phases such as Fe2O3, Fe3O4, and FeTiO3 can be ruled out. The similarity of the N K-edge spectra to O, and the presence of a strong x-ray linear dichroism signal for the N K-edge, indicates that N is substitutional for O in the rutile lattice and is not present as a secondary phase such as TiN. Simulations of the XANES spectra confirm substitution, although N appears to be present in more than one local environment. Neither Fe:TiO2 nor (Fe,N):TiO2 exhibit intrinsic room temperature ferromagnetism, despite the presence of mixed valent Fe(II)/Fe(III) in the reduced (Fe,N):TiO2 film.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  14. Superhydrophilic and Wetting Behavior of TiO2 Films and their Surface Morphologies

    International Nuclear Information System (INIS)

    TiO2 films, showing superhydrophilic behavior, are prepared by electron beam evaporation. Atomic force microscopy and the contact angle measurement were performed to characterize the morphology and wetting behavior of the TiO2 films. Most studies attribute the wetting behavior of TiO2 surfaces to their physical characteristics rather than surface chemistry. These physical characteristics include surface morphology, roughness, and agglomerate size. We arrange these parameters in order of effectiveness. Surface morphologies are demonstrated to be the most important. TiO2 films with particular morphologies show superhydrophilic behavior without external stimuli, and these thin films also show stable anti-contamination properties during cyclical wetting and drying. (cross-disciplinary physics and related areas of science and technology)

  15. Morphology control of cathodically deposited TiO2 films

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2005-02-15

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

  17. Third-harmonic generation measurement of nonlinearities in SiO2-TiO2 sol-gel films

    Science.gov (United States)

    Torruellas, W. E.; Weller-Brophy, L. A.; Zanoni, R.; Stegeman, G. I.; Osborne, Z.; Zelinski, B. J. J.

    1991-03-01

    Third-harmonic generation has been used to measure the magnitude and phase of the nonlinear susceptibility ?(3)(3?) of SiO2-TiO2 sol-gel thin films as a function of TiO2 concentration. Nonlinearities 20 times larger than those of fused silica were found, making such films useful for nonlinear optics in glass waveguides.

  18. Photosensitization of nanocrystalline TiO2 film electrode with cadmium sulphoselenide

    International Nuclear Information System (INIS)

    Nanocrystalline titanium dioxide (TiO2) thin films composed of densely packed nanometer-sized grains have been successfully deposited onto an indium-doped-tin oxide (ITO) substrate. Then cadmium sulphoselenide (CdSSe) thin film was deposited onto pre-deposited TiO2 to form a TiO2/CdSSe film, at low temperature using a simple and inexpensive chemical method. The X-ray diffraction, selected area electron diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and water contact angle techniques were used for film characterization. Purely rutile phase of TiO2 with super-hydrophilic and densely packed nanometer-sized spherical grains of approximate diameter 30-40 (±2) nm was observed. The increase in optical absorption was observed after CdSSe film deposition. Nest like surface morphology of CdSSe on TiO2 surface results in air trapping in the crevices which prevents water from adhering to the film with increase in water contact angle. Photosensitization of TiO2 with CdSSe was confirmed with light illumination intensity of 80 mW/cm2

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

    Science.gov (United States)

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

    2006-12-01

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

  20. Effect of hot-filament annealing in a hydrogen atmosphere on the electrical and structural properties of Nb-doped TiO2 sputtered thin films

    International Nuclear Information System (INIS)

    In this work Nb-doped TiO2 thin films were deposited by d.c.-pulsed reactive magnetron sputtering at 500 °C from a composite target with weight fractions of 96% Ti and 4% Nb, using oxygen as reactive gas. In order to enhance the conductive properties, the as-deposited samples were treated in vacuum with atomic hydrogen at a substrate temperature of 500 °C. The atomic hydrogen flow was generated by a hot filament, inside a high-vacuum chemical vapour deposition reactor, at a temperature of 1750 °C. In order to optimise the hydrogen hot-wire treatments, the H2 pressure was varied between 1.3 and 67 Pa, the treatment time was monitored between 1 and 5 min and the hot-filament current was changed between 12 and 17 A. Dark conductivity was measured as a function of temperature and its value at room temperature was extrapolated and used to assess the effect of the hydrogen annealing on the charge transport properties. A two-order of magnitude increase in dark conductivity was typically observed for optimised hydrogen treatments (10 Pa), when varying the hydrogen pressure, resulting in a minimum resistivity of ? 3 × 10?3 ? cm at room temperature. The maximum amount of atomic H incorporation in oxygen vacancies was determined to be ? 5.7 at.%. Carrier mobility and resistivity were also investigated using Hall effect measurements. Correlations between structural and electrical properties and the hydrogen treatment conditions are discussed. The conditions are discussed. The purpose of these films is to provide a transparent and conductive front contact layer for a-Si based photovoltaics, with a refractive index that better matches that of single and tandem solar cell structures. This can be achieved by an appropriate incorporation of a very small amount of cationic doping (Nb5+) into the titanium dioxide lattice.

  1. 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

  2. Ultrathin Films of TiO2 Nanoparticles at Interfaces.

    Science.gov (United States)

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

    2015-02-01

    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

  3. TiO2 and Fe-Doped TiO2 Thin Layers.

    Czech Academy of Sciences Publication Activity Database

    Dragounová, Pavlína; Morozová, Magdalena; Šolcová, Olga

    Bratislava : AXIMA Graphics Design & Printing Services, 2014, s. 26 ISBN 978-80-89475-13-1. [International Conference of Slovak Society of Chemical Engineering /41./. Tatranské Matliare (SK), 26.05.2014-30.05.2014] R&D Projects: GA TA ?R TA01020804 Grant ostatní: NATO (US) SPS984398 Institutional support: RVO:67985858 Keywords : sol-gel * TiO2 * Fe-TiO2 thin layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering

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

    Science.gov (United States)

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

    2012-09-01

    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.

  5. Sol-gel deposited TiO2 film on NiTi surgical alloy for biocompatibility improvement

    International Nuclear Information System (INIS)

    TiO2 thin films were prepared on NiTi surgical alloy by sol-gel method. The forming process, surface morphology and structure of the films were studied by X-ray diffraction and atomic force microscopy. The results showed that nm-scale TiO2 particles were embedded in the film of 205 nm thickness. The film existed mainly in the form of anatase, and the film was compact and smooth. The electrochemical corrosion measurement indicated that TiO2 thin film, as a protective layer, was effective for improving corrosion resistance of NiTi alloy. Additionally, in vitro blood compatibility of the film and NiTi alloy was evaluated by dynamic clotting time and blood platelets adhesion tests. The results showed that NiTi alloy coated with TiO2 film had improved blood compatibility

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

    International Nuclear Information System (INIS)

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

  7. Omnidirectional reflection from nanocolumnar TiO2 films

    Science.gov (United States)

    Leontyev, Viktor; Hawkeye, Matthew; Kovalenko, Andriy; Brett, Michael J.

    2012-10-01

    Anisotropic properties of columnar nanoporous thin films were utilized to design and fabricate interference mirrors with lossless omnidirectional reflection in the visible spectral range. Index graded columnar films with distributed Bragg reflector (DBR), sinusoidal, and Gaussian refractive index profiles were studied using finite-difference frequency-domain and finite-difference time-domain methods, with an emphasis on maximizing the omnidirectional reflection bandwidth. Titanium dioxide columnar films with sixteen period sinusoidal refractive index profile were fabricated using the glancing angle deposition technique and characterized by angle resolved transmittance measurements. Simulations and experimental measurements have shown the presence of the omnidirectional reflection band up to 5% wide for a film with a maximum refractive index nmax=2.3 and refractive index contrast ?n =0.8. Simulations further showed that with the optimal choice of the refractive index variation range, the omnidirectional reflection band can reach 10.5% width in TiO2 films with a sinusoidal index profile, 14.5% with a DBR index profile, and 12% with a Gaussian profile. Due to the optical anisotropy of the columnar films, the reflection bandwidth exceeded the corresponding value, observed in isotropic analogs, by a factor of three to four depending on the choice of the refractive index profile.

  8. Nanoindentation investigation of mechanical properties of ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 thin films deposited on stainless steel OC 404 substrate by spray pyrolysis

    International Nuclear Information System (INIS)

    Highlights: • ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 films were deposited by spray pyrolysis. • Surface morphology and structure of the films were characterized via SEM and X-ray. • Mechanical properties of films were investigated by nanoindentation and was established that their values exceed these for pure metals. - Abstract: Thin ZrO2, ZrO2–Y2O3, Al2O3 and TiO2 films were deposited by spray pyrolysis method on stainless steel OC 404 substrate with thickness 50 ?m. The thicknesses of obtained films varied from 0.50 to 0.64 ?m. The surface morphology and structure of the films were characterized by scanning electron microscopy in secondary electron imaging mode. The X-ray diffraction measurements for determination of the lattice parameters, the average crystallite size and the sample strain were performed. Mechanical properties of investigated films and substrate were investigated by nanoindentation experiments, using Nano Indenter G200 (Agilent Technologies). As a result of nanoindentation experiments, load–displacement curves were obtained and two mechanical characteristics of the substrate and investigated films – indentation hardness (HIT) and indentation modulus (EIT) – were calculated using Oliver and Pharr approximation method. Dependence of indentation modulus and indentation hardness on depth of indentation was investigated as well

  9. 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)

  10. Effect of SnO2 on the photocatalytical properties of TiO2 films

    International Nuclear Information System (INIS)

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

  11. Flexible InGaZnO thin film transistors using stacked Y2O3/TiO2/Y2O3 gate dielectrics grown at room temperature

    International Nuclear Information System (INIS)

    In this Letter, we report a low operation voltage and high mobility flexible InGaZnO thin-film transistor (TFT) using room-temperature processed Y2O3/TiO2/Y2O3 gate dielectric. The flexible IGZO TFT showed a low threshold voltage of 0.75 V, a small sub-threshold swing of 137 mV/decade, a good field effect mobility of 32.7 cm2/V s, and a large Ion/Ioff ratio of 1.7 x 106. The low operation voltage, small sub-threshold swing and high mobility could be ascribed to the combination of high-? TiO2 and large band gap Y2O3, which provide the potential to meet the requirements of low-temperature and low-power portable electronics. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. TiO2 and Fe2O3 films for photoelectrochemical water splitting.

    Science.gov (United States)

    Krysa, Josef; Zlamal, Martin; Kment, Stepan; Brunclikova, Michaela; Hubicka, Zdenek

    2015-01-01

    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. PMID:25584834

  13. 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.

  14. Photoactivity passivation of TiO2 nanoparticles using molecular layer deposited (MLD) polymer films

    International Nuclear Information System (INIS)

    Pigment-grade anatase TiO2 particles (160 nm) were passivated using ultra-thin insulating films deposited by molecular layer deposition (MLD). Trimethylaluminum (TMA) and ethylene glycol (E.G) were used as aluminum alkoxide (alucone) precursors in the temperature range of 100-160 oC. The growth rate varied from 0.5 nm/cycle at 100 oC to 0.35 nm/cycle at 160 oC. Methylene blue oxidation tests indicated that the photoactivity of pigment-grade TiO2 particles was quenched after 20 cycles of alucone MLD film, which was comparable to 70 cycles of Al2O3 film deposited by atomic layer deposition (ALD). Alucone films would decompose in the presence of water at room temperature and would form a more stable composite containing aluminum, which decreased the passivation effect on the photoactivity of TiO2 particles.

  15. Photoelectrochemical characterization and photocatalytic properties of mesoporous TiO2/ZrO2 films

    Directory of Open Access Journals (Sweden)

    Olga Linyucheva

    2006-02-01

    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.

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

    Directory of Open Access Journals (Sweden)

    2006-01-01

    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.

  17. Characterization of photoinduced self-exchange reactions at molecule-semiconductor interfaces by transient polarization spectroscopy: lateral intermolecular energy and hole transfer across sensitized TiO2 thin films.

    Science.gov (United States)

    Ardo, Shane; Meyer, Gerald J

    2011-10-01

    Transient anisotropy measurements are reported as a new spectroscopic tool for mechanistic characterization of photoinduced charge-transfer and energy-transfer self-exchange reactions at molecule-semiconductor interfaces. An anisotropic molecular subpopulation was generated by photoselection of randomly oriented Ru(II)-polypyridyl compounds, anchored to mesoscopic nanocrystalline TiO(2) or ZrO(2) thin films, with linearly polarized light. Subsequent characterization of the photoinduced dichromism change by visible absorption and photoluminescence spectroscopies on the nano- to millisecond time scale enabled the direct comparison of competitive processes: excited-state decay vs self-exchange energy transfer, or interfacial charge recombination vs self-exchange hole transfer. Self-exchange energy transfer was found to be many orders-of-magnitude faster than hole transfer at the sensitized TiO(2) interfaces; for [Ru(dtb)(2)(dcb)](PF(6))(2), where dtb is 4,4'-(C(CH(3))(3))(2)-2,2'-bipyridine and dcb is 4,4'-(COOH)(2)-2,2'-bipyridine, anchored to TiO(2), the energy-transfer correlation time was ?(ent) = 3.3 ?s while the average hole-transfer correlation time was = 110 ms, under identical experimental conditions. Monte Carlo simulations successfully modeled the anisotropy decays associated with lateral energy transfer. These mesoscopic, nanocrystalline TiO(2) thin films developed for regenerative solar cells thus function as active "antennae", harvesting sunlight and transferring energy across their surface. For the dicationic sensitizer, [Ru(dtb)(2)(dcb)](PF(6))(2), anisotropy changes indicative of self-exchange hole transfer were observed only when ions were present in the acetonitrile solution. In contrast, evidence for lateral hole transfer was observed in neat acetonitrile for a neutral sensitizer, cis-Ru(dnb)(dcb)(NCS)(2), where dnb is 4,4'-(CH(3)(CH(2))(8))(2)-2,2'-bipyridine, anchored to TiO(2). The results indicate that mechanistic models of interfacial charge recombination between electrons in TiO(2) and oxidized sensitizers must take into account diffusion of the injected electron and the oxidized sensitizer. The phenomena presented herein represent two means of concentrating potential energy derived from visible light that could be used to funnel energy to molecular catalysts for multiple-charge-transfer reactions, such as the generation of solar fuels. PMID:21861499

  18. Effects of annealing on the optical, structural, and chemical properties of TiO2 and MgF2 thin films prepared by plasma ion-assisted deposition.

    Science.gov (United States)

    Woo, Seouk-Hoon; Hwangbo, Chang Kwon

    2006-03-01

    Effects of thermal annealing at 400 degrees C on the optical, structural, and chemical properties of TiO2 single-layer, MgF2 single-layer, and TiO2/MgF2 narrow-bandpass filters deposited by conventional electron-beam evaporation (CE) and plasma ion-assisted deposition (PIAD) were investigated. In the case of TiO2 films, the results show that the annealing of both CE and PIAD TiO2 films increases the refractive index slightly and the extinction coefficient and surface roughness greatly. Annealing decreases the thickness of CE TiO2 films drastically, whereas it does not vary that of PIAD TiO2 films. For PIAD MgF2 films, annealing increases the refractive index and decreases the extinction coefficient drastically. An x-ray photoelectron spectroscopy analysis suggests that an increase in the refractive index and a decrease in the extinction coefficient for PIAD MgF2 films after annealing may be related to the enhanced concentration of MgO in the annealed PIAD MgF2 films and the changes in the chemical bonding states of Mg 2p, F 1s, and O is. It is found that (TiO2/MgF2) multilayer filters, consisting of PIAD TiO2 and CE MgF2 films, are as deposited without microcracks and are also thermally stable after annealing. PMID:16539248

  19. Microwave irradiation as an alternative source for conventional annealing: a study of pure TiO2, NiTiO3, CdTiO3 thin films by a sol gel process for electronic applications

    Science.gov (United States)

    Phani, A. R.; Santucci, S.

    2006-08-01

    The lower temperature and shorter timescale for microwave irradiation may be ascribed to the activating and facilitating effect of microwaves on solid-phase diffusion. Using the microwave-heating process, it is possible to achieve enhanced mechanical properties such as greater hardness, improved scratch resistance, and structure texturing. In the present investigation, thin films of pure TiO2 and their respective perovskite-structured thin films, namely NiTiO3 and CdTiO3, have been prepared by simple and cost-effective sol-gel processing on Si(100) substrates and subjected to irradiation with different microwave powers for 10 min. X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) techniques have been employed to characterize the structural, morphological and elemental composition of the films. It is evident that there is a dramatic change in the structural and morphological properties of the films irradiated in microwaves compared to conventional annealing at high temperature. A plausible mechanism for the formation of the anatase phase of TiO2 and perovskite structures with a rhombohedral phase formation at low microwave powers has also been discussed. This new innovative microwave heating could open a door for advanced technologies to cut process costs in the post-treatment of materials.

  20. Microwave irradiation as an alternative source for conventional annealing: a study of pure TiO2, NiTiO3, CdTiO3 thin films by a sol-gel process for electronic applications

    International Nuclear Information System (INIS)

    The lower temperature and shorter timescale for microwave irradiation may be ascribed to the activating and facilitating effect of microwaves on solid-phase diffusion. Using the microwave-heating process, it is possible to achieve enhanced mechanical properties such as greater hardness, improved scratch resistance, and structure texturing. In the present investigation, thin films of pure TiO2 and their respective perovskite-structured thin films, namely NiTiO3 and CdTiO3, have been prepared by simple and cost-effective sol-gel processing on Si(100) substrates and subjected to irradiation with different microwave powers for 10 min. X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) techniques have been employed to characterize the structural, morphological and elemental composition of the films. It is evident that there is a dramatic change in the structural and morphological properties of the films irradiated in microwaves compared to conventional annealing at high temperature. A plausible mechanism for the formation of the anatase phase of TiO2 and perovskite structures with a rhombohedral phase formation at low microwave powers has also been discussed. This new innovative microwave heating could open a door for advanced technologies to cut process costs in the post-treatment of materials

  1. Two-component transparent TiO2/SiO2 and TiO2/PDMS films as efficient photocatalysts for environmental cleaning.

    Czech Academy of Sciences Publication Activity Database

    Novotná, P.; Zita, J.; Krýsa, J.; Kalousek, Vít; Rathouský, Ji?í

    2007-01-01

    Ro?. 79, ?. 2 (2007), s. 179-185. ISSN 0926-3373 R&D Projects: GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40400503 Keywords : TiO2 * SiO2 * PDMS * thin film Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.651, year: 2007

  2. 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.

  3. Ultrafast nonresonant response of TiO2 nanostructured films.

    Science.gov (United States)

    Portuondo-Campa, E; Tortschanoff, A; van Mourik, F; Chergui, M

    2008-06-28

    We present a detailed study of the nonresonant third-order ultrafast response of TiO(2) nanostructured films, combining a classical heterodyned optical Kerr effect experiment, with two polarization selective Kerr techniques, based on transient lensing and phase modulation effects. The complementarity of these techniques is highlighted and demonstrated with calculations. Different aspects of the experimental results are addressed in detail and, finally, the possibilities of performing experiments on liquid dynamics in the pores of TiO(2) films, are discussed in the light of the present results. PMID:18601376

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

    International Nuclear Information System (INIS)

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

  5. Synthesis of amorphous TiO2 modified ZnO nanorod film with enhanced photocatalytic properties

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of amorphous TiO2 modified ZnO nanorod films. • A thin layer of amorphous TiO2 was dispersed over the surface of nanorod. • Disordered TiO2 phase improved the optical absorption. • The samples showed enhanced photocatalytic activity. - Abstract: Amorphous TiO2 modified ZnO nanorod films were synthesized via multi-step processes: ZnO nanorod films were prepared by a wet chemical method. Amorphous TiO2 was then anchored on the tops and sides of the nanorods through immersion in tetrabutyltitanate solution for hydrolysis. The as-prepared samples were characterized for the phase structure, chemical state and surface morphology as well as optical absorption using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and ultraviolet–visible (UV–vis) spectrophotometer. The results showed that the nanorod films were covered by amorphous TiO2 layers, and their visible light absorption ability was strengthened. The photocatalytic studies revealed that TiO2 modified films exhibited enhanced photocatalytic efficiency for decomposition of methyl orange under ultraviolet–visible excitation, which might be attributed to the increased UV–vis light absorption and the separation of the charge carrier and prolonged electron lifetime due to the interface between TiO2 and ZnO

  6. Resistive Switching in ALD ZnO and TiO2 Films

    Science.gov (United States)

    Waggoner, Todd; Co, John

    2010-03-01

    Resistive switching in metal oxide thin films has recently become a major scientific interest due to the possibility of producing low power, non-volatile resistive random access memory (ReRAM). Theories proposed for the switching mechanism typically involve the migration of oxygen vacancies under an applied electric field. Resulting from local increases in vacancy concentration, conducting filaments can form between device electrodes. The process is reversible by either applying a stronger voltage bias across the device to burn out the filaments or by reversing the applied field. This allows for the design of devices with unipolar or bipolar operation. A material comparison of ZnO and TiO2 thin films grown by atomic layer deposition (ALD) demonstrate different switching behavior in our devices. ALD TiO2 films have been prepared in the past but results typically show a wide variance. Here ZnO and TiO2 are directly compared utilizing Al electrodes. So far most work has been done using Pt electrodes on TiO2 thin films. Investigations show that device yield, performance, cycle endurance, and stability appear to differ significantly as a result of the chosen dielectric.

  7. 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

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

    International Nuclear Information System (INIS)

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

  9. Enhance of electrical properties of resistive switches based on Sr0.1Ba0.9TiO3 and TiO2 thin films by employing a Ni-Cr alloy as contact

    International Nuclear Information System (INIS)

    We have investigated the electric-field-induced resistance-switching phenomena of ReRAM cells based on Sr0.1Ba0.9TiO3 and TiO2 thin films fabricated by rf-sputtering technique. Thin films were sandwiched between Pt, Ti and nichrome bottom electrode and Cu top electrode. The I-V measurements at room temperature are non-linear and hysteretic. Cells based on Sr0.1Ba0.9TiO3 present a unipolar resistance-switching phenomenon and it is symmetric with respect to the voltage polarity, while cells based on TiO2 have a bipolar resistance-switching with asymmetric behavior. From the I-V measurements we demonstrated that the nichrome enhances the resistance-switching characteristics of the cells. A reduction of the voltage needed to achieve the HRS-LRS and LRS-HRS transitions are found and a very clear transition between these states is accomplished, in comparison with ReRAM cells fabricated with Pt and Ti electrodes, whose voltage values are large and no clear transitions are presented. This improvement in resistance-switching behavior can be explained due to O2 vacancies formed in the interface because higher affinity for oxygen of nickel and chromium.

  10. Thin Films

    Science.gov (United States)

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

    2014-11-01

    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.

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

    OpenAIRE

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

    2009-01-01

    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...

  12. Photovoltaic performance improvement of dye-sensitized solar cells through introducing In-doped TiO2 film at conducting glass and mesoporous TiO2 interface as an efficient compact layer

    International Nuclear Information System (INIS)

    In-doped TiO2 thin film was introduced at the interface of fluorine-doped tin oxide (FTO) substrate and mesoporous TiO2 film by spin-coating method, and its application as a new compact layer material for dye-sensitized solar cells (DSSCs) was investigated. The scanning electron microscopy (SEM), UV-visible spectroscopy, current-voltage characteristics, Mott-Schottky analysis, electrochemical impedance spectroscopy (EIS) analysis and open-circuit voltage decay (OCVD) technique are used to characterize the morphology, optical transmittance and flat-band potentials (Vfb) of In-doped titania compact film and its effect to the photoelectron conversion process. It was found that In-doping increased the transmittance of TiO2 compact layer, the interfacial resistance between FTO substrate and porous TiO2 film and the flat-band potential of TiO2 film. The In-doped TiO2 compact layer effectively suppressed the charge recombination from FTO to the electrolyte, increased the optical absorption of dye and then increased the short-circuit photocurrent density (Jsc). Furthermore, In-doped TiO2 compact layer acted as a weak energy barrier, which increased the electron density in the mesoporous TiO2 film, thus improved open-circuit photovoltage (Voc). As a result, the overall energy conversion efficiency of the DSSC with In-doped TiO2 compact layer was enhanced by 11.9% and 6.9% compared to the DSSC without compact layer and with pure TiO2 compact layer, respectively. It indicated that In-doped TiO2 is a promising compact layer material for dye-sensitized solar cells

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

    Science.gov (United States)

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

    2015-03-01

    Titanium dioxide (TiO2) thin films were prepared on ITO (2 2 2) 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 (1 0 1) 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 ?645 cm-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 3.15-3.63 eV and indirect band gap of 3.48-3.73 eV, 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 400 sccm of hydrogen at room temperature was studied and discussed.

  14. 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)

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

    1318-13-01

    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.

  15. Structural characterization and photocatalytic activity of ultrathin TiO2 films fabricated by Langmuir-Blodgett technique with octadecylamine

    International Nuclear Information System (INIS)

    TiO2 thin films with nanometer-scale thicknesses were prepared by the hydrolysis of titanium potassium oxalate using octadecylamine (ODA) Langmuir-Blodgett (LB) films as templates. After optimizing conditions in immersion process, the amount of TiO2 generated in the ODA LB film was found to be precisely controlled by the number of deposited ODA layers. Morphological measurements showed that uniform TiO2 film with surface roughness of less than 1.3 nm could be prepared from the monolayer LB films through subsequent heat-treatment process, while generation of cracks became less noticeable on the 5-layer film after heat-treatment at lower holding temperature with slow heating rate. In addition, photocatalytic activities of the TiO2 films were examined from the decomposition of cadmium stearate (CdSt) LB films and stearic acid (SA) cast films for different time intervals of irradiation with UV light. Atomic force microscopy measurements showed that an almost flat surface of the CdSt LB film changes to a moth-eaten appearance as a result of decomposition under UV light irradiation. Furthermore, the post-heat-treatment at higher temperatures resulted in decreased photocatalytic activity of the TiO2 film for the decomposition of SA cast film.

  16. 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.

  17. Assembly of self-assembled monolayer-coated Al2O3 on TiO2 thin films for the fabrication of renewable superhydrophobic-superhydrophilic structures.

    Science.gov (United States)

    Nishimoto, Shunsuke; Sekine, Hitomi; Zhang, Xintong; Liu, Zhaoyue; Nakata, Kazuya; Murakami, Taketoshi; Koide, Yoshihiro; Fujishima, Akira

    2009-07-01

    A renewable superhydrophobic-superhydrophilic pattern with a minimum dimension of 50 microm is prepared from octadecyltrimethoxysilane self-assembled monolayer-covered superhydrophobic Al2O3 overlayers on a superhydrophilic TiO2 surface via self-assembly and calcination of boehmite (AlOOH.nH2O) particles. The resulting Al2O3 layer plays dual roles as a superhydrophobic layer and as a UV-blocking layer for the underlying TiO2. PMID:19563218

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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.

  19. Nanostructured multilayer TiO2-Ge films with quantum confinement effects for photovoltaic applications.

    Science.gov (United States)

    Khan, Abdul Faheem; Mehmood, Mazhar; Aslam, Muhammad; Shah, Syed Ismat

    2010-03-01

    Multilayer TiO(2)-Ge thin films have been deposited using electron beam evaporation and resistive heating. The thickness of the TiO(2) layers is 20 nm, while the thickness of the Ge layers varies from 2 to 20 nm with a step of 2 nm away from the substrate. These films were characterized by studying their optical, electrical, and structural properties. The films were annealed at various temperatures up to 500 degrees C for 2 h. The films are amorphous up to an annealing temperature of 400 degrees C, although Raman spectra suggest short-range ordering (and adjustments). The films annealed at 450 and 500 degrees C exhibit X-ray reflections of Ge and anatase TiO(2). Illumination in sunlight increases the conductivity of the as-deposited and annealed films. The band gap of the amorphous films changes from 1.27 to 1.41 eV up to 400 degrees C; the major contribution is possibly through direct transition. Two band gap regimes are clearly seen after 450 and 500 degrees C, which have been assigned to an indirect band gap at about 1.2 eV and a direct band gap at about 1.8 eV. Conductivity of the multilayer films has been higher than that of pure Ge film. The conductivity increases with annealing temperature with abrupt increase at about 380 degrees C. The results imply that the TiO(2)-Ge multilayer films may be employed as heterojunctions with tunable band gap energy as related to quantum confinement effects. PMID:20045525

  20. Effect of 79 MeV Br ion irradiation on the surface features of rutile TiO2 thin film

    International Nuclear Information System (INIS)

    In this study, rutile titanium dioxide thin films deposited on Si (100) substrates by DC magnetron sputtering are irradiated by 79 MeV Br ions. Though each Br ion is expected to amorphize the medium along its path, the film remains crystalline even at the highest fluence of irradiation. The evolution of surface of the films with Br ion fluence is studied using atomicforce microscopy. The films were found to smoothen under dense electronic excitation of Br ions. The irregular shape grain of the pristine films convert to circular shape at a fluence of 1 × 1013 Br ions cm?2. Power spectral density (PSD) analysis of the AFM images indicates that irradiation induced smoothing of the surfaces is governed by the surface diffusion process.

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

    International Nuclear Information System (INIS)

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

  2. Photocatalytic acetaldehyde oxidation in air using spacious TiO2 films prepared by atomic layer deposition on supported carbonaceous sacrificial templates

    OpenAIRE

    Verbruggen, Sammy W.; Deng, Shaoren; Kurttepeli, Mert; Cott, Daire J.; Vereecken, Philippe M.; Bals, Sara; Martens, Johan A.; Detavernier, Christophe; Lenaerts, Silvia

    2014-01-01

    Supported carbon nanosheets and carbon nanotubes served as sacrificial templates for preparing spacious TiO2 photocatalytic thin films. Amorphous TiO2 was deposited conformally on the carbonaceous template material by atomic layer deposition (ALD). Upon calcination at 550{\\deg}C, the carbon template was oxidatively removed and the as-deposited continuous amorphous TiO2 layers transformed into interlinked anatase nanoparticles with an overall morphology commensurate to the or...

  3. Characterization of TiO2 films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Epitaxial titanium dioxide thin films with anatase and rutile structure have been deposited by pulsed laser deposition (ArF excimer laser and Nd:YAG laser) under the controlled O2 atmosphere. Epitaxial anatase films have been prepared on several kinds of oxide substrates with different lattice parameters. The anatase TiO2 (001) films have been prepared on LaAlO3 (001), LSAT (001), SrTiO3 (001) and YSZ (001) substrates. Also the high quality epitaxial rutile TiO2 (100) films were grown on ?-Al2O3 (0001) substrate. In addition, Cr, Nb, Ta and W doped rutirle TiO2 (100) films were successfully prepared. The quality of films and crystallographic relationships were assessed by x-ray diffraction, x-ray pole figures and Rutherford backscattering spectroscopy (RBS)/channeling. The photocatalytic activity was evaluated by Photo-Induced Charge Separation measurement (PITCS) and measuring decomposition rates of methylene blue. (author)

  4. 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)

    Vesborg, Peter Christian Kjærgaard; In, Su-il

    2010-01-01

    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%.

  5. Enhanced TiO2 surface electrochemistry with carbonised layer-by-layer cellulose-PDDA composite films.

    Science.gov (United States)

    Vuorema, Anne; Shariki, Sara; Sillanpää, Mika; Thielemans, Wim; Nelson, Geoffrey W; Foord, John S; Dale, Sara E C; Bending, Simon; Marken, Frank

    2011-05-28

    In this report we demonstrate a versatile (and potentially low-cost) cellulose nano-whisker-based surface carbonisation method that allows well-defined films of TiO(2) nanoparticles surface-modified with carbon to be obtained. In a layer-by-layer electrostatic deposition process based on TiO(2) nanoparticles, cellulose nano-whiskers, and poly(diallyl-dimethylammonium) or PDDA are employed to control the ratio of surface carbon to TiO(2). Characterisation based on optical, AFM, XRD, and XPS methods is reported. Electrochemical measurements suggest improved access to surface states, dopamine binding at the anatase surface, and surface redox cycling aided by the thin amorphous carbon film in mesoporous TiO(2). In future, the amorphous carbon layer method could be applied for surface processes for a wider range of semiconductor or insulator surfaces. PMID:21499622

  6. Electrochemical deposition of p-type CuSCN in porous n-type TiO2 films

    International Nuclear Information System (INIS)

    We present an energy band model and a method for filling p-type CuSCN in n-type porous TiO2 film. The energy band model is based on the interface energy levels between TiO2/CuSCN heterojunction and the aqueous electrolyte. The whole deposition process is divided into three stages: the uniform nucleation on the internal surface at positive potential, the crystal growth with the cathodic potential shifting negatively and the thermal activated growth at constant potential. This was demonstrated by the electrochemical experiment combining the hydrothermal process. It was found that the obtained TiO2/CuSCN heterojunction exhibited good rectification characteristics, indicating that an intimate electrical contact was formed between the large internal surface of TiO2 film and CuSCN. This novel hydrothermal-electrochemical method may be valuable for fabricating extremely thin absorber (eta)-solar cells and other semiconductor devices

  7. Optical, electrical and dielectric properties of TiO 2-SiO 2 films prepared by a cost effective sol-gel process

    Science.gov (United States)

    Vishwas, M.; Rao, K. Narasimha; Gowda, K. V. Arjuna; Chakradhar, R. P. S.

    2011-12-01

    Titanium dioxide (TiO 2) and silicon dioxide (SiO 2) thin films and their mixed films were synthesized by the sol-gel spin coating method using titanium tetra isopropoxide (TTIP) and tetra ethyl ortho silicate (TEOS) as the precursor materials for TiO 2 and SiO 2 respectively. The pure and composite films of TiO 2 and SiO 2 were deposited on glass and silicon substrates. The optical properties were studied for different compositions of TiO 2 and SiO 2 sols and the refractive index and optical band gap energies were estimated. MOS capacitors were fabricated using TiO 2 films on p-silicon (1 0 0) substrates. The current-voltage ( I- V) and capacitance-voltage ( C- V) characteristics were studied and the electrical resistivity and dielectric constant were estimated for the films annealed at 200 °C for their possible use in optoelectronic applications.

  8. Preparation and study of microstructures, optical properties and oscillator parameters of titanium (IV) oxide (TiO2) film

    Science.gov (United States)

    Al-Ahmad, Alaa Yassin

    2012-08-01

    In this study, Titanium (IV) Oxide (TiO2) film has been prepared and characterized by X-ray diffraction (XRD). The XRD pattern of TiO2 film of anatase phase exhibit very sharp peaks at 25° and 47.85°. According to Scherrer's formula the grain size of anatase (101) phase TiO2 nananoparticle is 38.5 nm. The optical properties and constants of TiO2 film of thickness (4 ?m) have been investigated at room temperature. The transmittance, reflectance and absorbance spectra are measured in the wavelength range (340-900 nm). Optical constants of TiO2 film are derived from the transmission spectra and the refractive index dispersion of the film. The oscillator energy, E 0 dispersion energy, E d , the static refractive index, n 0, and other parameters have been determined by the single oscillator Wemple-DiDomenico method. This film can be used in the form of thin film in dye-sensitized solar cells.

  9. 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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Scientific Electronic Library Online (English)

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

    2010-09-01

    Full Text Available SciELO Brazil | Language: English Abstract in english In this work is investigated the optimal conditions for deposition of pure- phase anatase and rutile thin films prepared at low temperatures (less than 150ºC) by reactive dc magnetron sputtering onto well- cleaned p- type Si substrates. For this, the variation of deposition plasma parameters as subs [...] trate- 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's noticeable a strong dependence of surface roughness with parameters studied.

  12. Spectrally selective reflector surfaces for heat reduction in concentrator solar cells : modeling and applications of TiO(2):Nb-based thin films

    OpenAIRE

    Maghanga, Christopher M.; Niklasson, Gunnar A.; Granqvist, Claes G.; Mwamburi, Mghendi

    2011-01-01

    The energy conversion efficiency of a conventional pn junction solar cell decreases as the temperature increases, and this may eventually lead to failures in the photovoltaic system, especially if it uses concentrated solar radiation. In this work, we show that spectrally selective reflector (SSR) surfaces can be important for reducing the heat buildup on passively cooled solar cells. We outline a computational scheme for optimizing DC magnetron-sputtered TiO(2):Nb-based SSRs tailored for sil...

  13. Antibacterial effect of silver modified TiO2/PECVD films

    Science.gov (United States)

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

    2009-08-01

    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.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2013-10-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-14

    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.

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

    Scientific Electronic Library Online (English)

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

    2011-03-01

    Full Text Available 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.

  18. Influence of porous morphology on optical dispersion properties of template free mesoporous titanium dioxide (TiO 2) films

    Science.gov (United States)

    Sudhagar, P.; Sathyamoorthy, R.; Chandramohan, S.

    2008-01-01

    This paper focuses the influence of porous morphology on the microstructure and optical properties of TiO 2 films prepared by different sol concentration and calcination temperatures. Mesoporous TiO 2 thin films were prepared on the glass substrates by sol-gel dip coating technique using titanium (IV) isopropoxide. Porous morphology of the films can be regulated by chemical kinetics and is studied by scanning electron microscopy. The optical dispersion parameters such as refractive index ( n), oscillator energy ( Ed), and particle co-ordination number ( Nc) of the mesoporous TiO 2 films were studied using Swanepoel and Wemple-DiDomenico single oscillator models. The higher precursor concentration (0.06 M), films exhibit high porosity and refractive index, which are modified under calcination treatment. Calcinated films of low metal precursor concentration (0.03 M) possess higher particle co-ordination number ( Nc = 5.05) than that of 0.06 M films ( Nc = 4.90) due to calcination at 400 °C. The lattice dielectric constant ( E?) of mesoporous TiO 2 films was determined by using Spintzer model. Urbach energy of the mesoporous films has been estimated for both concentration and the analysis revealed the strong dependence of Urbach energy on porous morphology. The influence of porous morphology on the optical dispersion properties also has been explained briefly in this paper.

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

    International Nuclear Information System (INIS)

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

  20. Sunlight photocatalysis in coral-like TiO2 film

    International Nuclear Information System (INIS)

    To improve the quantum efficiency of TiO2 film irradiated by sunlight, coral-like TiO2 film composed by nanorods and a nanonet structure was prepared by anodizing Ti in HF-Na2SiF6-FeCl3 solution. The coral-like TiO2 film revealed an improvement over the TiO2 nanotube under sunlight in both optical absorption and photocatalytic activity such as photodegradation of reactive brilliant red. Under sunlight irradiation, the photoelectrocatalytic degradation rate of a coral-like TiO2/Ti electrode (45.2%) was about four times higher than that of a nanotube TiO2/Ti electrode (11.9%) at 1.5 V potential application.

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

    Science.gov (United States)

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

    2014-12-01

    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%.

  2. 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

  3. Enhanced adsorption of atrazine from aqueous solution by molecularly imprinted TiO2 film

    Science.gov (United States)

    Zhang, Chunjing; Yan, Jinlong; Zhang, Chunxiao; Yang, Zhengpeng

    2012-07-01

    TiO2 film imprinted by atrazine molecule at the surface of quartz crystal was prepared using molecular imprinting and surface sol-gel process. The molecularly imprinted TiO2 film was characterized by scanning electron microscopy and cyclic voltammetry, and the atrazine adsorption was investigated by quartz crystal microbalance (QCM) technique. In comparison with non-imprinted TiO2 film, the molecularly imprinted TiO2 film exhibits high selectivity for atrazine, better reversibility and a much higher adsorption capacity for the target molecule, the adsorption equilibrium constant estimated from the in situ frequency measurement is about 6.7 × 104 M-1, which is thirteen times higher than that obtained on non-imprinted TiO2 film.

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

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Habibi

    2008-04-01

    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.

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

    Science.gov (United States)

    Quan, Xie; Ruan, Xiuli; Zhao, Huimin; Chen, Shuo; Zhao, Yazhi

    2007-05-01

    Titanium dioxide (TiO2) nanotube film electrodes are fabricated by the anodic oxidation method. Scanning electron microscopy (SEM) showed that these tubes were well aligned and organized into high-density uniform arrays. XRD analysis showed the TiO2 nanotubes to be in the anatase crystal form. The TiO2 nanotube film electrode exhibited increased photoelectrocatalytic (PEC) capability compared to a traditional TiO2 film electrode fabricated using the anodizing method for pentachlorophenol (PCP) degradation in aqueous solution. The bias potential, pH value, and electrolyte concentration were shown to be important factors influencing the degradation of PCP by the PEC method using the TiO2 nanotube film electrode as the working electrode. PMID:16815608

  6. Elliptical concave microlens arrays built in the photosensitive TiO2/ormosils hybrid films

    Science.gov (United States)

    Zhang, Xuehua; Que, Wenxiu; Javed, Hafiz M. Asif; Wei, Wei

    2014-11-01

    Photosensitive TiO2/organically modified silane hybrid thin films were prepared by a low-temperature sol-gel spin-coating technique. Optical and structural properties of the hybrid films with different titanium contents were characterized by prism coupling technique, UV-visible spectroscopy, Fourier transform infrared spectroscopy, and thermal gravimetric analysis. Advantages for fabrication of elliptical concave micro-lens arrays (MLAs) based on the as-prepared hybrid films were demonstrated by combining polydimethylsiloxane soft mold with a UV-cured imprint technique. Results indicate that the as-prepared hybrid films have great applicability for the fabrication of photonic components, and the fabrication technique provides a simple and cost-effective way for the fabrication of the sol-gel elliptical concave MLAs.

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

    Directory of Open Access Journals (Sweden)

    R. Nassiri

    2013-11-01

    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.

  8. 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...

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

    International Nuclear Information System (INIS)

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

  10. Synthesis and characterization of TiO2 nanoparticle films coated with organic dyes

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    J. C. Johnson

    2009-01-01

    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.

  13. 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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  16. Thin layers of TIO2/polythiophene composites using electrodeposition method.

    Czech Academy of Sciences Publication Activity Database

    Pavlík, Martin; Pfleger, Ji?í; Hebestreit, N.; Plieth, W.; Wang, G.

    Dresden : Leibnitz Institut für Festkörper und Werkstofforschung Dresden, 2002. s. 42. [ Bunsen -Kolloquium Charge Transfer at Conducting Polymers: Fundamentals and Applications /81./. 21.09.2002-23.09.2002, Dresden] R&D Projects: GA ?R GA202/00/1152 Keywords : electrodeposition * nanoparticles * TIO2 Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Preparation and characterization of polyvinyl alcohol films containing TiO2 nanoparticles

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

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

    2012-06-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Sigrid Bernstorff

    2010-11-01

    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.

  20. Effects of Morphology of Anatase TiO2 Nanotube Films on Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

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

    2010-09-01

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

  1. Structure, magnetic and optical properties of polycrystalline Co-doped TiO2 films

    International Nuclear Information System (INIS)

    Co-doped TiO2 films were fabricated under different conditions using reactive facing-target magnetron sputtering. Co doping improves the transformation of TiO2 from anatase phase to rutile phase. The chemical valence of doped Co in the films is +2. All the films are ferromagnetic with a Curie temperature above 340 K. The average room-temperature moment per Co of the Co-doped TiO2 films fabricated at 1.86 Pa decreases from 0.74 ?B at x=0.03 to 0.02 ?B at x=0.312, and decreases from 0.54 to 0.04 ?B as x increases from 0.026 to 0.169 for the Co-doped TiO2 films fabricated at 0.27 Pa. The ferromagnetism originates from the oxygen vacancies created by Co2+ dopants at Ti4+ cations. The optical band gaps value (Eg) of the Co-doped TiO2 films fabricated at 1.86 Pa decreases linearly from 3.35 to 2.62 eV with the increasing x from 0 to 0.312. For the Co-doped TiO2 films fabricated at 1.86 Pa, the Eg decreases linearly from 3.26 to 2.53 eV with increasing x from 0 to 0.350.

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

    OpenAIRE

    Nassiri, R.; Mohammadinafchi, A.

    2013-01-01

    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....

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

    OpenAIRE

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

    2010-01-01

    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...

  4. Nanostructured Fe2O3/TiO2 thick films prepared by screen printing

    OpenAIRE

    Aleksic, Obrad S.; Djuric, Zorka Z.; Nikolic, Maria V.; Nikola Tasic; Marina Vukovic; Zorica Marinkovic-Stanojevic; Nenad Nikolic; Nikolic, Pantelija M.

    2013-01-01

    Nanostructured single layered (pure TiO2, pure ?-Fe2O3 and mixed Fe2O3/TiO2 with two different oxide ratios, 2 : 3 and 3 : 2) and double layered (TiO2 layer over a Fe2O3 layer) thick films have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100 °C and sintered at 650 °C/60 minutes. Stru...

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

    Science.gov (United States)

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

    2012-05-01

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

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    2009-03-01

    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.

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

    Science.gov (United States)

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

    2014-11-01

    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.

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

    Science.gov (United States)

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

    2014-10-01

    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

  10. Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.

    Science.gov (United States)

    Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

    2010-09-01

    Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity. PMID:20799710

  11. Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

    International Nuclear Information System (INIS)

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

  12. Calcination Conditions on the Properties of Porous TiO2 Film

    Science.gov (United States)

    Zhang, Wenjie; Pei, Xiaobei; Bai, Jiawei; He, Hongbo

    2014-03-01

    Porous TiO2 films were deposited on SiO2 precoated glass-slides by sol-gel method using PEG1000 as template. The strongest XRD diffraction peak at 2? = 25.3° is attributed to [101] plane of anatase TiO2 in the film. The increases of calcination temperature and time lead to stronger diffraction peak intensity. High transmittance and blue shift of light absorption edge are the properties of the film prepared at high calcination temperature. The average pore size of the films increases with the increasing calcination temperature as the result of TiO2 crystalline particles growing up and aggregation, accompanied with higher specific surface area. Photocatalytic activity of porous TiO2 films increases with the increasing calcination temperature. The light absorption edge of the films slightly moves to longer wavelength region along with the increasing calcination time. The mesoporous film calcinated at 500 °C for 2 h has the highest transmittance, the maximum surface area, and the maximum total pore volume. Consequently, the optimum degradation activity is achieved on the porous TiO2 film calcinated at 500 °C for 2 h.

  13. Influence of substrate bias voltage on the physical, electrical and dielectric properties of RF magnetron sputtered TiO2 films

    International Nuclear Information System (INIS)

    Titanium oxide (TiO2) finds potential applications in various fields such as solar cells, optical coatings due to its high refractive index and it also has been widely used in memory devices owing to its high dielectric constant. TiO2 films have been deposited on p-type silicon (100) substrates by RF magnetron sputtering technique. Thickness, structure and surface morphology of the films were analyzed by using ?-step profilometer, Raman spectroscopy and atomic force microscope respectively. Thin film capacitors of the type Al/TiO2/Si were fabricated by evaporation of Aluminium on to the TiO2 films. The current - voltage and capacitance - voltage characteristics were carried out to understand the electrical conduction and dielectric properties of the deposited films with a stack of Al/TiO2/Si. The leakage current density was decreased and capacitance was increased with increase of substrate bias voltage.

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

    Science.gov (United States)

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

    2014-10-01

    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.

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

    International Nuclear Information System (INIS)

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

  16. Tuning the resistive switching properties of TiO2-x films

    Science.gov (United States)

    Ghenzi, N.; Rozenberg, M. J.; Llopis, R.; Levy, P.; Hueso, L. E.; Stoliar, P.

    2015-03-01

    We study the electrical characteristics of TiO2-x-based resistive switching devices fabricated with different oxygen/argon flow ratio during the oxide thin film sputtering deposition. Upon minute changes in this fabrication parameter, three qualitatively different device characteristics were accessed in the same system, namely, standard bipolar resistive switching, electroforming-free devices, and devices with multi-step breakdown. We propose that small variations in the oxygen/ argon flow ratio result in relevant changes of the oxygen vacancy concentration, which is the key parameter determining the resistive switching behavior. The coexistence of percolative or non-percolative conductive filaments is also discussed. Finally, the hypothesis is verified by means of the temperature dependence of the devices in low resistance state.

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

    International Nuclear Information System (INIS)

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

  18. (Photo)Electrochemical characterization of nanoporous TiO2 and Ce-doped TiO2 sol–gel film electrodes

    International Nuclear Information System (INIS)

    Highlights: ? Prevention of rutile phase formation by cerium doping. ? Observation of a photo-current maximum in dependence of the TiO2 film thickness. ? Limitation of photocurrent at higher radiant power by electron–hole recombination. ? Current doubling and suppression of charge recombination by methanol addition. ? 3D array of nanoparticles shows features similar to a solid crystalline electrode. - Abstract: Focusing on effects of charge separation limitations and doping on the photoactivity of TiO2, different nanoporous TiO2 film electrodes were prepared by the sol–gel or the suspension methods, respectively. X-ray diffraction (XRD) characterization revealed for all undoped TiO2 electrodes (TiO2-SG and TiO2-P25) mixed phases of anatase and rutile, whereas the 2%CeTiO2-SG electrode showed only anatase phase pattern, revealing that the incorporation of Ce ions prevented phase transformation. The (photo)electrochemical characterization of the nanoporous TiO2 film electrodes was performed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the dark and under UV irradiation, respectively. A photocurrent maximum depending on the film thickness was observed at about 13 ?m for all TiO2 electrodes investigated. The photocurrent responses of Ce-doped sol–gel TiO2 electrodes were comparably low, indicating an enhanced electicating an enhanced electron–hole recombination at the Ce ion levels within the band gap of TiO2. A porous electrode model was adapted for the fitting of the experimental EIS data. The potential and incident radiant power density dependence of the heterogeneous charge transfer reaction (RCT) and the coupled transport of photogenerated electrons to the collector electrode (ZS) were ascribed to promoted charge carrier separation and migration, i.e. electron drift dominated over diffusion. Consequently, the dependence of different discrete impedance elements was discussed, supposing a macroscopic electric field across the 3D array of interconnected TiO2 nanoparticles that form the film electrodes. Besides photocurrent doubling, addition of methanol as a hole scavenger revealed the limitation of the overall reaction by the heterogeneous charge transfer reaction, in particular at high radiant power densities.

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

    International Nuclear Information System (INIS)

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

  20. Optical Study of Ultrathin TiO2 Films for Photovoltaic and Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    Arturas SUCHODOLSKIS

    2014-06-01

    Full Text Available TiO2 ultrathin films of thickness below 20 nm were deposited by reactive RF magnetron sputtering. The optical properties of TiO2 films were investigated by various optical techniques including UV-VIS-NIR spectroscopic ellipsometry. The Scanning Probe Microscopy (SPM was used to determine thickness and surface roughness of the deposited films. The correlation between preparation conditions of ultrathin TiO2 films and their physical properties has been studied. The analysis of optical data revealed the parameters of deposited films and intrinsic properties of TiO2 material before and after annealing. We found that deposited layers were predominantly amorphous with high porosity at the top sample, and absence of porosity at the bottom of TiO2 layer. Annealing considerably improves structural order of the studied samples and the film transforms to the polycrystalline anatase phase. Also we evaluated the energy bandgap (about 3.1 eV – 3.2 eV which increases after annealing (above 3.3 eV and it is  close to the bandgap of anatase. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6328

  1. Dye-Sensitized Nanostructured TiO2 Film Based Photoconductor

    CERN Document Server

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

    2008-01-01

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

  2. Hydroxyapatite coatings on titanium dioxide thin films prepared by pulsed laser deposition method

    International Nuclear Information System (INIS)

    Hydroxyapatite (HAp) coated on titanium dioxide (TiO2) thin films has been developed to supplement the defects of both TiO2 and HAp. Thin films have been prepared by pulsed laser deposition (PLD) method using HAp and HAp(10%) + TiO2 targets. X-ray diffraction (XRD) shows that there are many small peaks of Ca10(PO4)6(OH)2 crystal, and no impurity other than HAp is detected in HAp films prepared using pure HAp target. The composition ratio of the film was analyzed by X-ray photoelectron spectroscopy (XPS). HAp coatings on TiO2 thin films have been prepared using HAp(10%) + TiO2 targets. XRD and XPS measurements suggest that crystalline HAp + TiO2 thin films are obtained by the PLD method using HAp(10%) + TiO2 target

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

    International Nuclear Information System (INIS)

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

  4. On the spray-drying deposition of TiO 2 photocatalytic films

    Science.gov (United States)

    Uzunova-Bujnova, M.; Todorovska, R.; Milanova, M.; Kralchevska, R.; Todorovsky, D.

    2009-11-01

    The photocatalytic activity of TiO 2 films deposited on different substrates by the spray-drying method using suspensions of commercially available TiO 2 (Degussa P25 or Tronox) as starting material was studied. The influence of the type of the initial TiO 2, preparation conditions (temperature of the substrate during the film deposition, temperature of the post-deposition annealing), substrate material (glass, fused silica, stainless steel and graphite), the presence of additives in the spraying suspension (polyethylene glycol, ethylene glycol and acetylacetone) and its sonication before spraying on the morphology, size of crystallites and phase composition (rutile/anatase ratio) was studied. Optimal conditions for spray deposition of the films are suggested.

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

    International Nuclear Information System (INIS)

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

  6. Structural analysis of TiO2 films grown using microwave-activated chemical bath deposition

    International Nuclear Information System (INIS)

    TiO2 layer films were grown using the microwave (MW)-activated chemical bath deposition technique on two different indium tin oxide substrates. The TiO2 films are studied to determine their structural response when changing the MW heating power. Thickness (areal density), oxygen concentration profile, composition and surface homogeneity were determined using Rutherford backscattering spectrometry, nuclear reaction analysis and atomic force microscopy. The analysis showed that the composition, thickness and surface structure of the films are highly influenced by MW heating power. The substrate, acting as seed for nucleation, influences the layer thickness, indicating that a thinner layer of TiO2 is obtained for the more conducting substrates. The oxygen concentration profile is constant in the TiO2 layer at low MW heating, power (?20%). The rugosity of the samples and the non-homogeneity increase with the MW heating power. If the MW heating power is high enough pinholes in the TiO2 layer of the order of the sample thickness are produced

  7. Structural and optical properties of Ag : TiO2 nanocomposite films prepared by magnetron sputtering

    OpenAIRE

    Adochite, R.; Torrell, M.; Cunha, L.; Alves, E.; Barradas, N. P.; Cavaleiro, A.; Rivie?re, J. P.; Eyidi, D.; Vaz, F.

    2011-01-01

    Three sets of nanocomposite films consisting of different atomic concentrations of Ag dispersed in a TiO2 dielectric matrix were deposited by DC reactive magnetron sputtering, and subjected to several thermal annealing experiments in vacuum, for temperatures ranging from 200 to 600 ºC. The main goal of the present study is to analyse the optical properties of the as-deposited and annealed films in order to clarify the role of Ag inclusions in the TiO2 dielectric matrix. The influence of the ...

  8. Investigation of thermal diffusivity of nano-structured TiO2 films

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  10. Thermally induced crystallization of TiO2 and ZrO2 optical films

    International Nuclear Information System (INIS)

    Thin films of TiO2 and ZrO2 were produced by ion-beam sputter deposition onto fused silica and silicon substrates. Raman scattering and scanning electron microscopy (SEM) were used to monitor crystallization. After the amorphous titania films were deposited with high and low ion-beam current densities and by e-beam evaporation, and were thermally annealed, they showed evidence of crystallization in the vicinity of 300 to 3500C. When zirconia amorphous films of fused silica substrates were thermally annealed, they first crystallized into mixed tetragonal and monoclinic phases at 4500C. Further heating beyond 9000C showed a transformation to a mixed monoclinic and cubic phase. On silicon substrates, the lower temperature crystallization occurs near 7000C. At the same time, SEM micrographs revealed progressive structural changes form smooth, faint columns to larger grain columns at high annealing temperatures. The crystalline transformations in both oxides coincided with changes in refractive index, lowering of the optical band gap, and significant increases in optical absorption and scattering loss

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

    Science.gov (United States)

    Gusak, Viktoria; Heiniger, Leo-Philipp; Graetzel, Michael; Langhammer, Christoph; Kasemo, Bengt

    2012-05-01

    Indirect nanoplasmonic sensing (INPS) is an experimental platform exploiting localized surface plasmon resonance (LSPR) detection of processes in nanomaterials, molecular assemblies, and films at the nanoscale. Here we have for the first time applied INPS to study dye molecule adsorption/impregnation of two types of TiO(2) materials: thick (10 ?m) mesoporous films of the kind used as photoanode in dye-sensitized solar cells (DSCs), with particle/pore size in the range of 20 nm, and thin (12-70 nm), dense, and flat films. For the thick-film experiments plasmonic Au nanoparticles were placed at the hidden, internal interface between the sensor surface and the mesoporous TiO(2). This approach provides a unique opportunity to selectively follow dye adsorption locally in the hidden interface region inside the material and inspires a generic and new type of nanoplasmonic hidden interface spectroscopy. The specific DSC measurement revealed a time constant of thousands of seconds before the dye impregnation front (the diffusion front) reaches the hidden interface. In contrast, dye adsorption on the dense, thin TiO(2) films exhibited much faster, Langmuir-like monolayer formation kinetics with saturation on a time scale of order 100 s. This new type of INPS measurement provides a powerful tool to measure and optimize dye impregnation kinetics of DSCs and, from a more general point of view, offers a generic experimental platform to measure adsorption/desorption and diffusion phenomena in solid and mesoporous systems and at internal hidden interfaces. PMID:22486708

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

    Science.gov (United States)

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

    2012-11-01

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

  13. Densification of amorphous sol-gel TiO2 films: An X-ray reflectometry study

    International Nuclear Information System (INIS)

    Sol-gel TiO2 thin films were dip coated on soda lime glass substrate using tetraisopropoxide as titania precursor. Four withdrawal speeds were tested and the resulting dried thin films have been annealed at 400 oC, 450 oC and 500 oC for 1 h. Glancing Incidence X-ray Diffraction has revealed the amorphous nature of the thin films whatever is the annealing temperature. In order to study the thin films densification, X-ray Reflectometry curves have been fitted by a three layers Parrat model and by the Distorded Wave Born Approximation (DWBA) box model which provides more details on the Electron Density Profile. The presence of high density layers localized at the film surface and at the substrate-film interface has been evidenced for the annealed films. The DWBA fitting method allows us to point out a density gradient, probably arising from the initial packing density and to the constraint due to the substrate, along the film thickness.

  14. Synthesis of V-doped TiO2 films by chemical bath deposition and the effect of post-annealing on their properties

    International Nuclear Information System (INIS)

    Amorphous composite films, composed of a Ti1?xVxO2 solid-solution phase and a V2O5 phase, were produced by chemical bath deposition and subsequently air-annealed at various temperatures up to 550 °C. The microstructure and chemical composition of the as-prepared and annealed films were investigated by a combinatorial experimental approach using Scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. Ultraviolet–Visible Spectrometry was applied to determine the optical band gap of the as-prepared and annealed films. It followed that the incorporation of vanadium in the as-deposited films reduces the optical band gap of TiO2 from about 3.8 eV to 3.2 eV. Annealing of the films up to 350 °C leads to slight increase of band gap, as attributed to a reduction of the defect density in the initially amorphous oxide films due to the gradual development of long-range order and a concurrent reduction of the V4+-dopant concentration in the Ti1?xVxO2 solid-solution phase. The films crystallized upon annealing in air at 550 °C, which resulted in drastic changes of the phase constitution, optical absorbance and surface morphology. Due to the lower solubility of V4+ in crystalline TiO2, V4+ segregates out of the crystallizing Ti1?xVxO2 solid-solution phase, forming> solid-solution phase, forming crystalline V2O5 at the film surface. - Highlights: ? Incorporation of vanadium in TiO2 thin film reduces its optical band gap. ? Amorphous V-doped TiO2 and TiO2-V2O5 composite films were air-annealed up to 550ºC. ? Annealing of the films up to 350 °C leads to slight increase of the band gap.

  15. Low-temperature sputtering of crystalline TiO2 films

    International Nuclear Information System (INIS)

    This article reports on the investigation of reactive magnetron sputtering of transparent, crystalline titanium dioxide films. The aim of this investigation is to determine a minimum substrate surface temperature Tsurf necessary to form crystalline TiO2 films with anatase structure. Films were prepared by dc pulsed reactive magnetron sputtering using a dual magnetron operating in bipolar mode and equipped with Ti(99.5) and ceramic Ti5O9 targets. The films were deposited on unheated glass substrates and their structure was characterized by x-ray diffraction and surface morphology by atomic force microscopy. Special attention is devoted to the measurement of Tsurf using thermostrips pasted to the glass substrate. It was found that (1) Tsurf is considerably higher (approximately by 100 deg. C or more) than the substrate temperature Ts measured by the thermocouple incorporated into the substrate holder and (2) Tsurf strongly depends on the substrate-to-target distance ds-t, the magnetron target power loading, and the thermal conductivity of the target and its cooling. The main result of this study is the finding that (1) the crystallization of sputtered TiO2 films depends not only on Tsurf but also on the total pressure pT of sputtering gas (Ar+O2), partial pressure of oxygen pO2, the film deposition rate a, the film deposition rate aD, and the film thickness h (2) crystalline TiO2 films with well developed anatase structure can be formed at Tsurf=160 deg. C and low values of aD?5 nm/min (3) the crystalline structure of TiO2 film gradually changes from (i) anatase through (ii) anatase+rutile mixture, and (iii) pure rutile to x-ray amorphous structure at Tsurf=160 deg. C and pT=0.75 Pa when pO2 decreases and aD increases above 5 nm/min, and (4) crystallinity of the TiO2 films decreases with decreasing h and Tsurf. Interrelationships between the structure of TiO2 film, its roughness, Tsurf, and aD are discussed in detail. Trends of next development are briefly outlined

  16. Anisotropic nanometal particles on TiO2 film using sol-gel method

    Science.gov (United States)

    Kawazu, Mitsuhiro; Nara, Masatoshi; Yamamoto, Hiroaki

    2001-12-01

    Recently, people have become interested in fine metal particles such as Au,Ag,Pt and Pd because of their importance in applications such as optical devices, electronic devices and heterogeneous catalysis. (1 to approximately 3) In particular, anisotropic fine metal particles have been researched as one of the key technologies to light control. We propose a new technique for preparation of anisotropic Au fine particles. SiO2 film dispersed Au fine particles was prepared by sol-gel method on TiO2 film made by sputtering. Silicon alkoxides and Au salts were used as raw materials for SiO2 film dispersed Au fine particles. The gel film was given heat- treatment at 300 degrees Celsius, and then Au salts we decomposed into Au fine particles. It was identified by TEM (transmission electron microscope) observation that anisotropic Au fine particles were trapped at the interface between SiO2 film and TiO2 film. In addition, compositional distribution in depth direction was investigated. It was confirmed by X-ray photoelectron spectroscopy that Au was distributed on the interface between TiO2 film and SiO2 film and the SiO2 film surface. Furthermore, the polarized light spectrum of Au fine particles separated out on the interface between TiO2 film and SiO2 film were measured, and as a result a polarized absorption spectrum caused by a minor axis and a major axis of Au fine particles were observed.

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

    OpenAIRE

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

    2010-01-01

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

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

    Directory of Open Access Journals (Sweden)

    M. M. Hasan

    2010-09-01

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

  19. Photo catalytic activity of nanocrystalline TiO2-based films produced by Evades method

    International Nuclear Information System (INIS)

    Nanocrystalline TiO2-based films have been deposited using a novel and cost-effective Electrostatic Spray Assisted Vapour Deposition (Evades) method for photo catalysis applications. The deposited films mainly have anatase phase with very small amounts of rutile or breakout. This paper reports the photo catalytic activity of the nano structured TiO2-based films under solar light irradiation. The influence of Peg additive and Fe doping on the film photo catalytic efficiency will be presented, as well as the structural changes with the additive and dopant. The results demonstrate that Evades process can produce nanocrystalline anatase films with good photo catalytic activity, and further enhancement of photo catalytic efficiency can be achieved by introducing appropriate Fe doping

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

    Science.gov (United States)

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

    2014-06-01

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

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

    International Nuclear Information System (INIS)

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

  2. Preparation and Characterization of Fe-Doped TiO2 Thin Layers.

    Czech Academy of Sciences Publication Activity Database

    Dragounová, Pavlína; Morozová, Magdalena; Šolcová, Olga

    - : -, 2014, P.25. ISBN N. [Pannonian Symposium on Catalysis /12./. T?eš? (CZ), 16.09.2014-20.09.2014] R&D Projects: GA TA ?R TA01020804 Grant ostatní: NATO (US) SPS984398 Institutional support: RVO:67985858 Keywords : sol-gel technique * Fe-doped TiO2 * thin layers Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://pannonia2014.icpf.cas.cz/wp-content/uploads/2014/09/abstrakty_final.pdf

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

    International Nuclear Information System (INIS)

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

  4. Nanostructured Fe2O3/TiO2 thick films prepared by screen printing

    Directory of Open Access Journals (Sweden)

    Obrad S. Aleksic

    2013-09-01

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

  5. Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD

    OpenAIRE

    Chiu, Po-kai; Lee, Chao-te; Chiang, Donyau; Cho, Wen-hao; Hsiao, Chien-nan; Chen, Yi-yan; Huang, Bo-ming; Yang, Jer-ren

    2014-01-01

    Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material ...

  6. Comparison of TiO2-doped SiO2 films from two organosilicon precursors

    Science.gov (United States)

    Bange, Jaspal P.; Patil, Lalit S.; Gautam, D. K.

    2011-01-01

    In present work the effect of two different source of silicon Tetraethylorthosilicate and Octamethylcyclotetrasiloxane on TiO2-doped SiO2 films have been studied. The study reveals that film properties depend on the precursors used for deposition. The deposited films are crystalline with broad peak between 2? = 20° - 30° corresponding to SiO2 and two strong peak appearing at 2? = 38.3° and 2? = 44.6° due to the (004) anatase phase and (210) rutile phase of TiO2. It is also clear from the SEM study that the particle size of films deposited using TEOS are smaller than the one deposited by OMCTS.

  7. Optical, dielectric and morphological studies of sol-gel derived nanocrystalline TiO 2 films

    Science.gov (United States)

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

    2009-10-01

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

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

    OpenAIRE

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

    2011-01-01

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

  9. Photoemission study of TiO2/VO2 interfaces

    OpenAIRE

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

  11. Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.

    Science.gov (United States)

    Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

    2011-12-01

    TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles. PMID:22409037

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

    Directory of Open Access Journals (Sweden)

    Mohammadreza Foruzanmehr

    2014-04-01

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

  13. A practical demonstration of water disinfection using TiO2 films and sunlight.

    Science.gov (United States)

    Gelover, Silvia; Gómez, Luis A; Reyes, Karina; Teresa Leal, Ma

    2006-10-01

    The scope of this study is the assessment of the efficiency of solar disinfection by heterogeneous photocatalysis with sol-gel immobilized (titanium dioxide) TiO2 films over glass cylinders. The solar disinfection process known as SODIS was considered as a reference. Spring water naturally polluted with coliform bacteria was exposed to sunlight in plastic bottles with and without TiO2 over simple solar collectors and the disinfection effectiveness was measured. Total and fecal coliforms quantification was performed by means of the chromogenic substrate method in order to obtain the efficiency of each disinfection treatment. The disinfection with TiO2 was more efficient than the SODIS process, inactivating total coliforms as well as fecal coliforms. On a sunny day (more than 1000 W m(-2) irradiance), it took the disinfection with immobilized TiO2 15 min of irradiation to inactivate the fecal coliforms to make them undetectable. For inactivation of total coliforms, 30 min was required, so that in less than half the time it takes SODIS, the treated water complies with the microbial standards for drinking water in Mexico. Another important part of this study has been to determine the bacterial regrowth in water after the disinfection processes were tested. After SODIS, bacterial regrowth of coliforms was observed. In contrast, when using the TiO2 catalyst, coliforms regrowth was not detected, neither for total nor for fecal coliforms. The disinfection process using TiO2 kept treated water free of coliforms at least for seven days after sun irradiation. This demonstration opens the possibility of application of this simple method in rural areas of developing countries. PMID:16949121

  14. Electronic structure of epitaxial anatase TiO2 films: Angle-resolved photoelectron spectroscopy study

    Science.gov (United States)

    Emori, Masato; Sugita, Mari; Ozawa, Kenichi; Sakama, Hiroshi

    2012-01-01

    Synchrotron-radiation angle-resolved photoelectron spectroscopy has been utilized to examine the bulk valence-band structure of anatase TiO2(001) thin films fabricated on LaAlO3(100) by pulsed laser deposition. The energy-momentum dispersion relation of O 2p-derived nonbonding, O 2p-Ti 3d ? bonding and several ? bonding states is determined experimentally. The nonbonding state at the top of the valence band is located at 4.3 eV at the center of the bulk Brillouin zone, and it shifts towards the shallower energies to 3.8 eV at the zone boundary. No other states with binding energies smaller than 3.8 eV are found on any other high-symmetry axes and points. Thus the valence-band maximum is located at the zone boundary. Our finding proves that anatase is an indirect-band-gap semiconductor.

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

    Science.gov (United States)

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

    2013-02-01

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

  16. Microwave Photocatalysis III. Transition Metal Ion-Doped TiO2 Thin Films on Mercury Electrodeless Discharge Lamps: Preparation, Characterization and Their Effect on the Photocatalytic Degradation of Mono-Chloroacetic Acid and Rhodamine B.

    Czech Academy of Sciences Publication Activity Database

    Žabová, Hana; Církva, Vladimír

    2009-01-01

    Ro?. 84, ?. 11 (2009), s. 1624-1630. ISSN 0268-2575 R&D Projects: GA ?R GA104/07/1212; GA ?R(CZ) GD203/08/H032 Institutional research plan: CEZ:AV0Z40720504 Keywords : microwave * photocatalysis * thin film Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.045, year: 2009

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

    Science.gov (United States)

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

    2012-10-24

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Lin-Yong Zhu

    2009-09-01

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

  1. FTIR and XPS investigation of Er-doped SiO2-TiO2 films

    International Nuclear Information System (INIS)

    The ultraviolet photo-induced chemical vapour deposition (UV-photo-CVD) process is a highly flexible and efficient technique for fabrication of thin oxide films. We report in this work the deposition of Er-doped SiO2-TiO2 thin films using UV-photo-CVD at temperatures between 350 and 500 deg. C. Erbium isopropoxide, titanium tetraisopropoxide (TTIP) and tetraethoxysilane (TEOS) are used as precursors. The films are measured to be around 20-100 nm in thickness with refractive indices from 1.60 to 1.90. The chemical, optical, microstructural and spectroscopic properties of the films have been investigated by Fourier transform infrared spectroscopy (FTIR), ellipsometry, photoluminescence (PL) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). High quality as-deposited films with various Ti/Si ratios and low carbon contents have been confirmed by XPS measurement. Er-doped titania-silica films were produced by UV-photo-CVD and effect of thermal and UV annealing on these films has also been studied

  2. Thin carbon layer coated Ti(3+)-TiO2 nanocrystallites for visible-light driven photocatalysis.

    Science.gov (United States)

    Jiang, Baojiang; Tang, Yunqi; Qu, Yang; Wang, Jian-Qiang; Xie, Ying; Tian, Chungui; Zhou, Wei; Fu, Honggang

    2015-03-01

    Black TiO2 containing Ti(3+) attracts enormous attention due to its excellent visible-light driven photocatalytic activity. Herein, an in situ thermal decomposition approach to synthesize uniform thin carbon coated Ti(3+)-TiO2 nanocrystals is presented. During the oleic acid-assisted solvothermal process, the crystal size and morphology of TiO2 were controlled through oleic acid with carboxylic acid groups. Then the residual small quantities of oleic acid anchored on TiO2 were used as a carbon source, which could be in situ pyrolyzed into a carbon layer on TiO2 at high temperature and under an inert atmosphere. Meanwhile, Ti(4+) species were partly reduced into Ti(3+) states/oxygen vacancies on the surface of TiO2 due to the carbothermal reduction reaction for the carbon-encapsulated Ti(3+)-TiO2 structure. A series of characterizations indicated that the 20-25 nm TiO2 nanocrystals obtained were wrapped evenly by 1-2 nm carbon layers, which had an important effect on the energy band structure change of TiO2. The presence of the carbon layer also improves the Ti(3+) stability and the conduction behavior of the composites. The Ti(3+) states/oxygen vacancies created on the surface of TiO2 were responsible for the remarkable photogenerated charge separation and extended visible-light absorption range. Furthermore, Ti(3+) states/oxygen vacancies and the carbon layer together could enhance the adsorption ability of O2 so as to promote the photogenerated electrons captured by the adsorbed O2, leading to a great increase in the charge separation. As a result, the composites exhibit high photocatalytic performance for organic pollutants under visible light irradiation. This simple and new method may pave the way to practical applications for efficient photocatalytic degradation under visible light. PMID:25697803

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-05-01

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

  5. Facile method for synthesis of TiO2 film and its application in high efficiency dye sensitized-solar cell (DSSC)

    International Nuclear Information System (INIS)

    Dye-sensitized solar cells (DSSC) is a device which converts a solar energy to electrical energy. Different with semiconductor thin film based solar cell, DSSC utilize the sensitized-dye to absorb the photon and semiconductor such as titanium dioxide (TiO2) and zinc oxide (ZnO) as a working electrode photoanode. In this report, the preparation of TiO2 film using a facile method of spray deposition and its application in DSSC have been presented. TiO2 photoanode was synthesized by growing the droplet of titanium tetraisopropoxide diluted in acid solution on the substrate of conductive glass flourine-doped tin oxide (FTO) with variation of precursor volume. DSSC was assemblied by sandwiching both of photoanode electrode and platinum counter electrode subsequently filling the area between these electrodes with triodine/iodine electrolite solution as redox pairs. The characterization of the as prepared DSSC using solar simulator (AM 1.5G, 100 mW/cm2) and I-V source meter Keithley 2400 showed that the performance of DSSC was affected by the precursor volume.. The overall conversion efficiency of DSSC using the optimum TiO2 film was about 1.97% with the open circuit voltage (Voc) of 0.73 V, short circuit current density (Jsc) of 4.61 mA and fill factor (FF) of 0.58

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

    Science.gov (United States)

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

    2011-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  9. Photocatalytic degradation characteristics of different organic compounds at TiO2 nanoporous film electrodes with mixed anatase/ rutile phases.

    Science.gov (United States)

    Jiang, Dianlu; Zhang, Shanqing; Zhao, Huijun

    2007-01-01

    Nanoporous TiO2 film electrodes with a mixed anatase/ rutile phase were prepared by dip-coating TiO2 nanoparticle colloid onto Indium Tin Oxide (ITO) conducting glass substrates and a subsequent calcination process at 700 degrees C for 16 h. The photocatalytic oxidation of a wide range of organic compounds has been studied using the photoelectrochemical method under the conditions that the photohole capturing step controls the overall photocatalytic processes. The characteristics of the mixed anatase/ rutile phase TiO2 film electrodes were compared with pure anatase phase TiO2 film electrodes to identify the key differences between them. The results revealed that different organic compounds, despite their difference in chemical entities, can be stoichiometrically mineralized at the mixed-phase TiO2 electrode under diffusion-controlled conditions, which is in great contrast to the situation at the pure anatase phase TiO2 electrode. The exceptional ability of the mixed-phase TiO2 electrodes for mineralization of organic compounds and their remarkable resistance to the inhibition by aromatic compounds at higher concentration has been explained by the synergetic effect of the rutile and anatase phases. For this type of mixed phase electrodes, upon absorption of UV light, the electron-transfer pathway from anatase phase to rutile phase facilitates the separation of photoelectron and photohole, extending the lifetime of the photoelectron and photohole. PMID:17265963

  10. EIS analysis on low temperature fabrication of TiO2 porous films for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    A low temperature (2 porous films with high efficiency in dye-sensitized solar cells (DSSCs) has been developed. The Ti(IV) tetraisopropoxide (TTIP) was added to the paste of TiO2 nanoparticles to interconnect the TiO2 particles. The electrochemical impedance spectroscopy (EIS) technique was employed to quantify the charge transport resistance at the TiO2/dye/electrolyte interface (Rct2) and electron lifetime in the TiO2 film (?e) under different molar ratios of TTIP/TiO2 and also at various TiO2 thicknesses. It was found that the Rct2 decreased as the molar ratio increased from 0.02 to 0.08, however, it increased at a molar ratio of 0.2 due to the reduction in surface area for dye adsorption. In addition, the characteristic frequency peak shifted to lower frequency at a molar ratio of 0.08, indicating the longer electron lifetime. As for the thickness effect, TiO2 film with a thickness around 17 ?m achieved the best cell efficiency. EIS study also confirmed that, under illumination, the smallest Rct2 was associated with a TiO2 thickness of 17 ?m, with the Rct2 increased as the thickness of TiO2 film increased. In the Bode plots, the characteristic frequency peaks shifted to higher frequency when the thickness of TiO2 increased from 17.2 tf TiO2 increased from 17.2 to 48.2 ?m, indicating the electron recombination increases as the thickness of the TiO2 electrode increases. Finally, to make better use of longer wavelength light, 30 wt% of larger TiO2 particle (300 nm) was mixed with P25 TiO2 as light scattering particles. It effectively increased the short-circuit current density and cell conversion efficiency from 7.44 to 8.80 mA cm-2 and 3.75 to 4.20%, respectively

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

    International Nuclear Information System (INIS)

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

  12. Microstructure and photocatalytic properties of WO3/TiO2 composite films by plasma electrolytic oxidation

    International Nuclear Information System (INIS)

    Highlights: ? WO3/TiO2 composite films were prepared by plasma eletrolytic oxidation in electrolytes containing different tungstate concentration. ? The influence of concentration of tungstate on the microstructure, photophysical properties and photocatalytic activity of the oxide films were investigated. ? The optimal concentration of tungstate to prepare WO3/TiO2 composite film with high photocatalytic activity was acquired. - Abstract: WO3/TiO2 composite films were prepared by plasma electrolytic oxidation in electrolytes containing different tungstate concentration. The morphology, topography, compositions, crystal structure and photophysical properties of films were characterized by SEM, AFM, EDX, XRD, XPS, UV-vis DRS and PL, the surface acidity of films was investigated by ATR-IR. The results showed porous films formed on the titanium substrate, consisted of Ti, O and W, and presented mixed crystal of anatase and rutile. Tungsten species were well-dispersed for WO3/TiO2 film formed in lower tungstate concentration, but were in crystalline WO3 in higher concentration. For WO3/TiO2 film prepared in optimal tungstate concentration, the highest content of anatase and the maximum surface acidity were obtained, and the recombination of holes and electrons was effectively inhibited. However, coupled-WO3 did not shift the optical abso/sub> did not shift the optical absorption to the visible region. The improvement of photocatalytic activity was attributed to the increased surface acidity, better separation between photo-induced carriers and higher content of anatase.

  13. Visible-light photocatalysis in nitrogen-carbon-doped TiO2 films obtained by heating TiO2 gel-film in an ionized N2 gas

    International Nuclear Information System (INIS)

    To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Nitrogen and carbon doping TiO2 films were obtained by heating a TiO2 gel in an ionized N2 gas. The as-synthesized TiO2-x-yNxCy films have shown an improvement over titanium dioxide in optical absorption and photocatalytic activity such as photodegradation of methyl orange under visible light. The process of the oxygen atom substituted by nitrogen and carbon was discussed. Oxygen vacancy induced by the formation of Ti3+ species and nitrogen and carbon doped into substitution sites of TiO2 have been proven to be indispensable for the enhance of photocatalytic activity, as assessed by UV-Vis Spectroscopy and X-ray photoemission spectroscopy

  14. Thin Films

    Science.gov (United States)

    Bagade, A. A.; Ganbavle, V. V.; Rajpure, K. Y.

    2014-08-01

    Cobalt ferrite thin films are deposited onto quartz glass substrates by chemical spray pyrolysis technique at different substrate temperatures using ferric nitrate and cobalt nitrate as precursors. Thermogravimetric analysis (TGA) study indicates the formation of CoFe2O4 by decomposition of cobalt and ferric nitrates after 800 °C. X-ray diffraction studies reveal that annealed films are polycrystalline in nature and exhibit spinel cubic crystal structure. Crystallite size varies from 39 to 44 nm with the substrate temperatures. Direct optical band gap energy of CoFe2O4 thin films is found to be 2.57 eV. The AFM images show that roughness and grain size of the CoFe2O4 thin film are about 9 and 138 nm, respectively. The measured DC resistivity of the deposited thin films indicates that as temperature increases the resistivity decreases indicating the semiconductor nature of the films. Decrease in dielectric constant (?') and loss tangent (tan?) has been observed with frequency and attains the constant value at higher frequencies. The AC conductivity of cobalt ferrite thin films increases with increase in frequency. Thus, the prepared films show normal dielectric performance of the spinel ferrite thin film. Room-temperature complex impedance spectra show the incomplete semicircles as films exhibit high resistance values at lower frequencies.

  15. Enhanced TiO2 surface electrochemistry with carbonised layer-by-layer cellulose-PDDA composite films.

    OpenAIRE

    Vuorema, A.; Shariki, S.; Sillanpa?a?, M.; Thielemans, W.; Nelson, Gw; Foord, Js; Dale, Se; Bending, S.; Marken, F.

    2011-01-01

    In this report we demonstrate a versatile (and potentially low-cost) cellulose nano-whisker-based surface carbonisation method that allows well-defined films of TiO(2) nanoparticles surface-modified with carbon to be obtained. In a layer-by-layer electrostatic deposition process based on TiO(2) nanoparticles, cellulose nano-whiskers, and poly(diallyl-dimethylammonium) or PDDA are employed to control the ratio of surface carbon to TiO(2). Characterisation based on optical, AFM, XRD, and XPS me...

  16. Solid-state source of atomic oxygen for low-temperature oxidation processes: Application to pulsed laser deposition of TiO2:N films

    Science.gov (United States)

    Ojima, Daiki; Chiba, Tetsuya; Shima, Kazunari; Hiramatsu, Hidenori; Hosono, Hideo; Hayashi, Katsuro

    2012-02-01

    An atomic oxygen (AO) source has been redesigned to coordinate with a pulsed laser deposition system and used to grow nitrogen-doped TiO2 films by deposition of TiN and simultaneous irradiation of the substrate with AO. The AO source uses an incandescently heated thin tube of zirconia as an oxygen permeation media to generate pure AO of low kinetic energy. The emission flux is calibrated using a silver-coated quartz crystal microbalance. The thin shape of the probe and transverse emission geometry of this emission device allow the emission area to be positioned close to the substrate surface, enhancing the irradiation flux at the substrate. AO irradiation is crucial for formation of TiO2 phases via oxidation of the deposited TiN laser plume, and is effective for decrease of the substrate temperature for crystallization of anatase phase to as low as around 200 °C.

  17. Solvent Effect on the Electrical and Optical Properties of Nano composite MEH-PPV: TiO2 Films for Organic Solar Cells Applications

    International Nuclear Information System (INIS)

    The influence of organic solvent on the electrical and optical properties of photodiodes based on poly[2-methoxy,5-(2'- ethylhexyloxy)-1,4-phenylene vinylene) MEHPPV) and nano-TiO2 nano composite are investigated. The films were prepared from TiO2 dispersed in MEH-PPV solutions in toluene, tetrahydrofuran (THF), xylene, chloroform and 1,3-dichlorobenzene (1,3- DCB) solvents at concentration of 20 mg/ 20 ml. The electrical properties of the MEH-PPV: TiO2 nano composite thin films were measured by solar simulator in dark and under illumination condition while the characterization of optical properties has using UV-VIS spectrophotometer to evaluate the absorbance. The solvent of 1,3-DCB shows a greater conductivity with 33.82x104 S.m-1 without photo response under illumination. (author)

  18. Existence, release, and antibacterial actions of silver nanoparticles on Ag–PIII TiO2 films with different nanotopographies

    OpenAIRE

    Li, Jinhua; Qiao, Yuqin; Zhu, Hongqin; Meng, Fanhao; Liu, Xuanyong

    2014-01-01

    Nanotopographical TiO2 films (including nanorod, nanotip, and nanowire topographies) were successfully fabricated on the metallic Ti surface via hydrothermal treatment and then underwent Ag plasma immersion ion implantation to incorporate Ag with TiO2. The surface morphology, phase component, and chemical composition before and after Ag–PIII were characterized. In view of the potential clinical applications, both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were us...

  19. Low temperature (150 °C) fabrication of high-performance TiO2 films for dye-sensitized solar cells using ultraviolet light and plasma treatments of TiO2 paste containing organic binder

    Science.gov (United States)

    Zen, Shungo; Inoue, Yuki; Ono, Ryo

    2015-03-01

    Dye-sensitized solar cells (DSSCs) require annealing of TiO2 photoelectrodes at 450 °C to 550 °C. However, such high-temperature annealing is unfavorable because it limits the use of materials that cannot withstand high temperatures, such as plastic substrates. In our previous paper, a low-temperature annealing technique of TiO2 photoelectrodes using ultraviolet light and dielectric barrier discharge treatments was proposed to reduce the annealing temperature from 450 °C to 150 °C for a TiO2 paste containing an organic binder. Here, we measure the electron diffusion length in the TiO2 film, the amount of dye adsorption on the TiO2 film, and the sheet resistance of a glass substrate of samples manufactured with the 150 °C annealing method, and we discuss the effect that the 150 °C annealing method has on those properties of DSSCs.

  20. TiO2-x films prepared by ion beam assisted deposition

    International Nuclear Information System (INIS)

    TiO2-x films were prepared by ion beam assisted deposition on an EATON Z-200 system, during which concurrent electron beam evaporation of titanium and bombardment with an inert gas ion beam were carried out in an O2 atmosphere. Xe+ and Ne+ ions with different current density and incident angles were used. The films were investigated using X-ray diffraction (XRD), glancing incident X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). RBS analysis shows that the films are nearly stoichiometric. XPS measurements reveal that the surface was fully oxidized, but Ti2+, Ti3+ and Ti4+ coexist on the Ar+-sputtered surface. XRD and GIXRD analyses show that almost all the films have rutile-type structure and (2 0 0) preferred orientation. After annealing the 2? angle shift to higher degrees and the (2 0 0) peak intensity increases, which means better crystallization and orientation

  1. Low-temperature hydrothermal formation of a net-like structured TiO 2 film and its performance of photogenerated cathode protection

    Science.gov (United States)

    Yun, Hong; Lin, Changjian; Li, Jing; Wang, Jingrun; Chen, Hongbo

    2008-12-01

    A net-like structured TiO 2 film was obtained with a low-temperature hydrothermal process, followed by acid washing and calcination in air. The photoelectrochemical properties of the net-like structured TiO 2 film coupled to 316L stainless steel (SS) for corrosion protection application in 3.5% NaCl solution were investigated and compared with the TiO 2 nanotube (TN) array prepared by electrochemical anodization. The TiO 2 films prepared by two different techniques were examined using SEM, Raman, XPS, photopotential variation with time, polarization measurements as well as EIS. It is found that the TiO 2 films with different surface morphologies in a comparable film thickness range both offer a distinctly photogenerated cathode protection for 316L SS under the white light illumination. The results have been discussed in terms of the structure of TiO 2 film and its performance of photogenerated cathode protection.

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

    International Nuclear Information System (INIS)

    Highlights: ? (I2)n-encapsulated TiO2 (I2-TiO2) and C-encapsulated TiO2 (C-TiO2) film electrodes were prepared. ? I2-TiO2 and C-TiO2 films show improved light absorbance in 400–550 nm. ? Lower electron transfer resistance and more negative flat band potentials were obtained from them. ? The photoelectrocatalytic activities of I2-TiO2 and C-TiO2 films were much higher than TiO2 film. - Abstract: Visible-light absorbing (I2)n-encapsulated TiO2 film (I2-TiO2 film) and C-encapsulated TiO2 film (C-TiO2 film) were fabricated and studied as film electrodes for their photoelectrochemical and photoelectrocatalytic (PEC) properties. The as-prepared film electrodes were characterized by scanning electronic microscopy, energy-dispersive X-ray spectroscopy and UV–visible diffuse reflectance spectroscopy. The photoelectrochemical properties were evaluated by the incident photo-to-current conversion efficiency, electrochemical impedance spectroscopy and Mott–Schottky analysis data. The results showed that I2-TiO2 and C-TiO2 films exhibited stronger absorption in the 400–550 nm range, lower electron transfer resistance and more negative flat band potentials comparing with pure TiO2 film. Moreover, b>2 film. Moreover, the photoelectrochemical ability of I2-TiO2 film is superior to that of C-TiO2 film. At a bias potential of 0.5 vs (Ag/AgCl)/V, the visible-light-induced PEC degradation ratios of rhodamine B and tetracycline on I2-TiO2 film or C-TiO2 film electrodes exceeded that on pure TiO2 electrode, with the improvement by a factor of about 5 or 3. The higher PEC activity of I2-TiO2 film and C-TiO2 film could be attributed to the enhancement of separation of electron-hole pair at the external electric field and the extension of the light response range of TiO2 to the visible light with a red shift in the band gap transition.

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

    International Nuclear Information System (INIS)

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

  4. One-step Fabrication of Crack-free, Hierarchically-ordered TiO2 Films via Self-assembly of Polystyrene Bead and Preformed TiO2

    International Nuclear Information System (INIS)

    Graphical abstract: One-step self-assembly of polystyrene bead and preformed TiO2 results in crack-free ordered TiO2 films with higher thickness and a meso/macroscopic scale hierarchical structure. The hierarchically-ordered TiO2-based solid-state dye-sensitized solar cell exhibited higher efficiency than a less-organized, nanoparticle-based cell using commercially available paste, indicating more effectiveness in solid-state high molecular weight systems. - Abstract: Crack-free, hierarchically-ordered TiO2 films were prepared via one-step co-assembly of a 400-nm polystyrene bead and hydrophilically preformed TiO2. Large volume loss of titanium(IV) bis(ammonium lactato) dihydroxide, a commonly used precursor, led to substantial crack formation of the film. However, the use of preformed TiO2 resulted in less cracked films with higher thickness and a meso/macroscopic scale hierarchical structure. This is because the preformed TiO2 particles electrostatically assembled onto the polystyrene bead surface, as confirmed by scanning electron microscope and a zeta potential analyzer. When these structures were implemented as photoanodes in quasi-solid-state dye-sensitized solar cells using a nanogel electrolyte, the efficiency of the preformed TiO2-based cell was 1.8-fold greater than that of a titanium(IV) bis(ammonium lactato) dihydroxide-based cell, indicating the importance of the precursor. Upon fabrication of solid-state dye-sensitized solar cells using a high molecular weight polymer and the TiCl4-treated TiO2 film, the efficiency was much greater than that of less-organized, nanoparticle-based cells fabricated with commercially available paste (Dyesol, 18NR-T). This indicates the increased effectiveness of the film in solid-state high molecular weight systems

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

    International Nuclear Information System (INIS)

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

  6. Coexistence of several structural phases in MOCVD TiO2 layers: evolution from nanometre to micrometre thick films

    International Nuclear Information System (INIS)

    The morphology and the structure of TiO2 films, grown on Si (1 0 0) substrates by metal organic chemical vapour deposition (MOCVD) was investigated in 5-500 nm thick films. It was shown that the TiO2 layer is mainly amorphous at the first stages of deposition. The growth of nanocrystallites begins inside the amorphous TiO2 layer, and it continues at the expense of the amorphous phase until the crystallized grains occupy the whole layer. Then, the film growth continues with a columnar structure. The coexistence of anatase and rutile phases was evidenced from the beginning of the growth by high resolution transmission electron microscopy and grazing incidence x-ray diffraction. However, the anatase growth overcomes that of rutile, leading to an inhomogeneous phase distribution as a function of the film thickness.

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

    DEFF Research Database (Denmark)

    Su, Ren; Bechstein, Ralf

    2012-01-01

    We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material for photovoltaic and photocatalysis applications can be controlled by adjusting the electrolyte composition. Compared to Fe-doped TiO2 films prepared with traditional phosphate- or silicate-based electrolytes, our newly synthesised Fe–TiO2 films contain solely Fe dopants, which results in excellent photocatalytic and photovoltaic performance under visible light irradiation.

  8. Passivation of pigment-grade TiO2 particles by nanothick atomic layer deposited SiO2 films

    International Nuclear Information System (INIS)

    Pigment-grade TiO2 particles were passivated using nanothick insulating films fabricated by atomic layer deposition (ALD). Conformal SiO2 and Al2O3 layers were coated onto anatase and rutile powders in a fluidized bed reactor. SiO2 films were deposited using tris-dimethylaminosilane (TDMAS) and H2O2 at 500 deg. C. Trimethylaluminum and water were used as precursors for Al2O3 ALD at 177 deg. C. The photocatalytic activity of anatase pigment-grade TiO2 was decreased by 98% after the deposition of 2 nm SiO2 films. H2SO4 digest tests were performed to exhibit the pinhole-free nature of the coatings and the TiO2 digest rate was 40 times faster for uncoated TiO2 than SiO2 coated over a 24 h period. Mass spectrometry was used to monitor reaction progress and allowed for dosing time optimization. These results demonstrate that the TDMAS-H2O2 chemistry can deposit high quality, fully dense SiO2 films on high radius of curvature substrates. Particle ALD is a viable passivation method for pigment-grade TiO2 particles

  9. Characteristics of phase transition of VO2 films grown on TiO2 substrates with different crystal orientations

    Science.gov (United States)

    Li, Jian; Dho, Joonghoe

    2014-10-01

    Vanadium dioxide (VO2) films were synthesized on two-side polished titanium dioxide (TiO2) substrates of five different crystal orientations, (0 0 1), (1 0 0), (1 0 1), (1 1 0), and (1 1 1), through pulsed laser deposition. X-ray diffraction measurements suggested that epitaxial VO2 films with good crystallinity were grown on TiO2. Transmission electron microscopy measurements showed the thickness of VO2 films to be about 50 nm and revealed the presence of an inter-mixing layer of ~10 nm thickness at the interface between VO2 and TiO2. A metal-insulator transition (MIT) showing a change in resistance of 3-4 orders of magnitude was observed in all samples. The MIT temperature (TMI) showed a significant variation with crystal orientation: the highest value of TMI was 350 K in VO2/TiO2(0 0 1) and the lowest value was 310 K in VO2/TiO2(1 1 0), and VO2 films for the (1 1 1), (1 0 1), and (1 0 0) orientations exhibited TMI ~315 K, 330 K, and 340 K, respectively. For infrared light, the change in the optical transmittance by the MIT was about 60%.

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

    International Nuclear Information System (INIS)

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

  11. Soporte de Nuevas Películas de TiO2 y TiO2/SiO2 sobre Gránulos de Poliéster para Aplicación en Fotocatálisis / Support of New TiO2 and TiO2/SiO2 Films on Polyester Granules for Photocatalytic Applications

    Scientific Electronic Library Online (English)

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

    Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Películas de TiO2 o TiO2/SiO2 fueron soportadas sobre gránulos de poliéster usando mecanismos de difusión y posterior tratamiento térmico a 100ºC. Se emplearon dos clases de geles. El primero fue preparado usando diferentes cantidades de TiO2, cloruro de metileno y silicona líquida. El segundo fue o [...] btenido por medio del método sol-gel, empleado para producir una matriz de sílice a partir de la hidrólisis el tetraetilo ortosilicato, en un medio orgánico de 2-propanol, en el cual se dispersó el fotocatalizador. Los precursores de cada sistema fueron agregados en diferentes relaciones para determinar su influencia en la estabilidad, propiedades y fotoactividad de las películas. La actividad fotocatalítica fue evaluada en la fotodegradación de metanol en fase gaseosa. Los resultados muestran la producción de materiales con alta resistencia, funcionalidad y actividad así como una fuerte relación entre la actividad fotocatalítica con las propiedades fisicoquímicas. Abstract in english Films of TiO2 and of TiO2/SiO2 were supported on polyester granules using a diffusion mechanism and a posterior thermal treatment to 100ºC. Two kinds of gels were used. The first one was prepared using different amounts of TiO2, methylene chloride and liquid silicone. The second one used the sol-gel [...] method to produce a silica matrix by adding tetraethyl orthosilicate, water and 2- propanol. After that the photocatalyst was dispersed in the gel. The precursors of each system were added in different amounts to determine their influence in the stability, properties and photoactivity of the films. The photocatalytic activity was tested in the methanol photodegradation in gas phase. The results show the production of materials with high resistance, functionality and activity as well as a strong dependence between the photocatalityc activity and efficiency with the physicochemical properties of the films.

  12. Soporte de Nuevas Películas de TiO2 y TiO2/SiO2 sobre Gránulos de Poliéster para Aplicación en Fotocatálisis Support of New TiO2 and TiO2/SiO2 Films on Polyester Granules for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Juan M Marín

    2008-01-01

    Full Text Available Películas de TiO2 o TiO2/SiO2 fueron soportadas sobre gránulos de poliéster usando mecanismos de difusión y posterior tratamiento térmico a 100ºC. Se emplearon dos clases de geles. El primero fue preparado usando diferentes cantidades de TiO2, cloruro de metileno y silicona líquida. El segundo fue obtenido por medio del método sol-gel, empleado para producir una matriz de sílice a partir de la hidrólisis el tetraetilo ortosilicato, en un medio orgánico de 2-propanol, en el cual se dispersó el fotocatalizador. Los precursores de cada sistema fueron agregados en diferentes relaciones para determinar su influencia en la estabilidad, propiedades y fotoactividad de las películas. La actividad fotocatalítica fue evaluada en la fotodegradación de metanol en fase gaseosa. Los resultados muestran la producción de materiales con alta resistencia, funcionalidad y actividad así como una fuerte relación entre la actividad fotocatalítica con las propiedades fisicoquímicas.Films of TiO2 and of TiO2/SiO2 were supported on polyester granules using a diffusion mechanism and a posterior thermal treatment to 100ºC. Two kinds of gels were used. The first one was prepared using different amounts of TiO2, methylene chloride and liquid silicone. The second one used the sol-gel method to produce a silica matrix by adding tetraethyl orthosilicate, water and 2- propanol. After that the photocatalyst was dispersed in the gel. The precursors of each system were added in different amounts to determine their influence in the stability, properties and photoactivity of the films. The photocatalytic activity was tested in the methanol photodegradation in gas phase. The results show the production of materials with high resistance, functionality and activity as well as a strong dependence between the photocatalityc activity and efficiency with the physicochemical properties of the films.

  13. Spectroscopic ellipsometry analysis of TiO2 films deposited by plasma enhanced chemical vapor deposition in oxygen/titanium tetraisopropoxide plasma

    International Nuclear Information System (INIS)

    TiO2 thin films were deposited at low pressure and temperature on silicon substrates using plasma enhanced chemical vapor deposition in oxygen rich O2/titanium tetraisopropoxide inductively coupled radiofrequency plasmas. The influence of substrate bias Vb (|Vb| ? 50 V) on the film properties was investigated. The results obtained by fitting ellipsometry spectra in the 1.5–6 eV range, using a three-sublayer physical model, are in good agreement with the film morphology when no bias is applied or Vb = ? 10 V. The refractive indices in the transparent range are enhanced at Vb = ? 50 V, according to a physical model which only includes a homogenous layer and a top roughness layer. Scanning electron microscopic views show that all the films exhibit a columnar structure, but layer compactness and organization increase with the bias. The film structure evolution as a function of Vb is also evidenced on the refractive index dispersion curves. Complementary X-ray diffraction and Fourier transform infrared spectroscopy measurements show that films are basically amorphous mixed with a small amount of anatase at the floating potential (Vb = 0), whereas applying a bias voltage leads to the enhancement of anatase phase and the appearance of rutile phase (Vb = ? 50 V). - Highlights: ? Plasma enhanced chemical vapor deposited TiO2 films ? Biasing effect on the lms ? Biasing effect on the structural and optical film properties ? Ellipsometric modeling with a gradient index sublayer ? Good agreement between ellipsometry analysis and scanning electron microscopy

  14. Optimization of TiO2 films prepared by reactive electron beam evaporation of Ti3O5

    International Nuclear Information System (INIS)

    In this paper, we report the development of TiO2 films by reactive electron beam evaporation, using a recently introduced Ti3O5 material as the starting material. During experiments, considerable effort was undertaken to optimize the deposition conditions for preparation of high quality TiO2 films. The processing window for preparation of high quality stoichiometric TiO2 was found to be quite narrow. The refractive index at 550 nm was approximately 2.41 for the samples. Combinations of spectroscopic ellipsometry and transmittance or reflectance spectrophotometry were used to measure and characterize the optical properties of the films. The surface morphology and microstructure were investigated by using atomic force microscopy and field emission scanning electron microscopy, respectively. The hardness and Young's modulus were calculated to be approximately 12 and 138 GPa by the nanoindentation measurements

  15. Epitaxial growth of TiO2 films with the rutile (110) structure on Ag(100)

    International Nuclear Information System (INIS)

    Ultrathin films of TiO2 were grown on Ag(100) by evaporation of titanium in the presence of O2 at a pressure in the 10-4 Pa range and annealing at 770 K. The composition of the deposited films was monitored by XPS and LEIS. The morphology at the nanometric scale of the TiO2 films and their crystallographic structure were investigated by means of STM, LEED and XPD. Above the monolayer coverage (at which the oxide film has a lepidocrocite-like structure), STM images show the formation of multilayer islands with a distribution of heights. XPD results indicate that these oxide islands have the rutile (110) structure and are epitaxially oriented with the sides of the oxide unit cell parallel to those of the substrate unit cell. The results of the DFT calculations justify the 3D growth of rutile (110) on Ag(100). The calculated strain energy required to match the metal substrate can explain the incommensurate growth of the overlayer in the direction of the long side of the oxide unit cell. The results of the calculations indicate that a commensurate growth of rutile (110) may be possible along the short side of the oxide unit cell, taking into account the relatively small strain energy to fit the lattice parameter of the substrate. The DFT calculations predict a considerable increase of the work function upon deposition of titania films on Ag(100), which can be attributed to a charge transfer from the metal to the 3d Ti empty statfer from the metal to the 3d Ti empty states.

  16. Epitaxial growth of TiO2 films with the rutile (110) structure on Ag(100)

    Science.gov (United States)

    Atrei, Andrea; Cortigiani, Brunetto; Ferrari, Anna Maria

    2012-11-01

    Ultrathin films of TiO2 were grown on Ag(100) by evaporation of titanium in the presence of O2 at a pressure in the 10-4 Pa range and annealing at 770 K. The composition of the deposited films was monitored by XPS and LEIS. The morphology at the nanometric scale of the TiO2 films and their crystallographic structure were investigated by means of STM, LEED and XPD. Above the monolayer coverage (at which the oxide film has a lepidocrocite-like structure), STM images show the formation of multilayer islands with a distribution of heights. XPD results indicate that these oxide islands have the rutile (110) structure and are epitaxially oriented with the sides of the oxide unit cell parallel to those of the substrate unit cell. The results of the DFT calculations justify the 3D growth of rutile (110) on Ag(100). The calculated strain energy required to match the metal substrate can explain the incommensurate growth of the overlayer in the direction of the long side of the oxide unit cell. The results of the calculations indicate that a commensurate growth of rutile (110) may be possible along the short side of the oxide unit cell, taking into account the relatively small strain energy to fit the lattice parameter of the substrate. The DFT calculations predict a considerable increase of the work function upon deposition of titania films on Ag(100), which can be attributed to a charge transfer from the metal to the 3d Ti empty states.

  17. A new coral structure TiO2/Ti film electrode applied to photoelectrocatalytic degradation of Reactive Brilliant Red

    International Nuclear Information System (INIS)

    A novel structure TiO2/Ti film was prepared on a titanium matrix using anodic oxidation technique and applied to degrade Reactive Brilliant Red (RBR) dye in simulative textile effluents. The film was characterized by Field-Emission Scanning Electron Microscope (FE-SEM), Laser Micro-Raman Spectrometer (LMRS), UV-vis spectrophotometer (UVS) and Photoelectrocatalytic (PEC) experiment. The results show that the surface morphology of the film is coral structure, and the crystal structure of the film is anatase. The absorbency of the coral structure TiO2/Ti film is 87-93% in the UV light region, and 77-87% in the visible light region. PEC experiment indicates that the photocurrent density of the coral structure TiO2/Ti film electrode achieves 160 ?A/cm2. The color and Chemical Oxygen Demand (COD) removal efficiencies of RBR achieve 73% and 60% in 1 h, respectively. These are 16% and 58% higher than those of nanotube TiO2/Ti film electrode. These were attributed to that these electrodes with different surface morphologies exhibit distinct surface areas and light absorption rate.

  18. In situ growth of a ZnO nanowire network within a TiO(2) nanoparticle film for enhanced dye-sensitized solar cell performance.

    Science.gov (United States)

    Bai, Yang; Yu, Hua; Li, Zhen; Amal, Rose; Lu, Gao Qing Max; Wang, Lianzhou

    2012-11-14

    ZnO nanowire networks featuring excellent charge transport and light scattering properties are grown in situ within TiO(2) films. The resultant TiO(2) /ZnO composites, used as photoanodes, remarkably enhance the overall conversion efficiency of dye-sensitized solar cells (DSSCs) by 26.9%, compared to that of benchmark TiO(2) films. PMID:22930471

  19. Thin Film?

    Science.gov (United States)

    Kariper, ?. Af?in

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  20. Graft copolymer-templated mesoporous TiO(2) films micropatterned with poly(ethylene glycol) hydrogel: novel platform for highly sensitive protein microarrays.

    Science.gov (United States)

    Son, Kyung Jin; Ahn, Sung Hoon; Kim, Jong Hak; Koh, Won-Gun

    2011-02-01

    In this study, we describe the use of organized mesoporous titanium oxide (TiO(2)) films as three-dimensional templates for protein microarrays with enhanced protein loading capacity and detection sensitivity. Multilayered mesoporous TiO(2) films with high porosity and good connectivity were synthesized using a graft copolymer consisting of a poly(vinyl chloride) (PVC) backbone and poly(oxyethylene methacrylate) (POEM) side chains as a structure-directing template. The average pore size and thickness of the TiO(2) films were 50-70 nm and 1.5 ?m, respectively. Proteins were covalently immobilized onto mesoporous TiO(2) film via 3-aminopropyltriethoxysilane (APTES), and protein loading onto TiO(2) films was about four times greater than on planar glass substrates, which consequently improved the protein activity. Micropatterned mesoporous TiO(2) substrates were prepared by fabricating poly(ethylene glycol) (PEG) hydrogel microstructures on TiO(2) films using photolithography. Because of non-adhesiveness of PEG hydrogel towards proteins, proteins were selectively immobilized onto surface-modified mesoporous TiO(2) region, creating protein microarray. Specific binding assay between streptavidin/biotin and between PSA/anti-PSA demonstrated that the mesoporous TiO(2)-based protein microarrays yielded higher fluorescence signals and were more sensitive with lower detection limits than microarrays based on planar glass slides. PMID:21291203