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

International Nuclear Information System (INIS)

Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

2011-01-01

There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . 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 TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

Structural and vibrational investigations of Nb-doped TiO2 thin films

International Nuclear Information System (INIS)

Uyanga, E.; Gibaud, A.; Daniel, P.; Sangaa, D.; Sevjidsuren, G.; Altantsog, P.; Beuvier, T.; Lee, Chih Hao; Balagurov, A.M.

2014-01-01

Highlights: • We studied the evolutions of structure for TiO 2 thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb 0.1 Ti 0.9 O 2 is smaller than for pure TiO 2 because doped Nb hinders the growth of the TiO 2 grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO 2 films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO 2 which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO 2 thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO 2 by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb 5+ ions into the lattice. The band gap energy of indirect transition of the TiO 2 thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV

Cytotoxicity Evaluation of Anatase and Rutile TiO2 Thin Films on CHO-K1 Cells in Vitro

Directory of Open Access Journals (Sweden)

Blanca Cervantes

2016-07-01

Full Text Available Cytotoxicity of titanium dioxide (TiO2 thin films on Chinese hamster ovary (CHO-K1 cells was evaluated after 24, 48 and 72 h of culture. The TiO2 thin films were deposited using direct current magnetron sputtering. These films were post-deposition annealed at different temperatures (300, 500 and 800 °C toward the anatase to rutile phase transformation. The root-mean-square (RMS surface roughness of TiO2 films went from 2.8 to 8.08 nm when the annealing temperature was increased from 300 to 800 °C. Field emission scanning electron microscopy (FESEM results showed that the TiO2 films’ thickness values fell within the nanometer range (290–310 nm. Based on the results of the tetrazolium dye and trypan blue assays, we found that TiO2 thin films showed no cytotoxicity after the aforementioned culture times at which cell viability was greater than 98%. Independently of the annealing temperature of the TiO2 thin films, the number of CHO-K1 cells on the control substrate and on all TiO2 thin films was greater after 48 or 72 h than it was after 24 h; the highest cell survival rate was observed in TiO2 films annealed at 800 °C. These results indicate that TiO2 thin films do not affect mitochondrial function and proliferation of CHO-K1 cells, and back up the use of TiO2 thin films in biomedical science.

Cytotoxicity Evaluation of Anatase and Rutile TiO2 Thin Films on CHO-K1 Cells in Vitro

Science.gov (United States)

Cervantes, Blanca; López-Huerta, Francisco; Vega, Rosario; Hernández-Torres, Julián; García-González, Leandro; Salceda, Emilio; Herrera-May, Agustín L.; Soto, Enrique

2016-01-01

Cytotoxicity of titanium dioxide (TiO2) thin films on Chinese hamster ovary (CHO-K1) cells was evaluated after 24, 48 and 72 h of culture. The TiO2 thin films were deposited using direct current magnetron sputtering. These films were post-deposition annealed at different temperatures (300, 500 and 800 °C) toward the anatase to rutile phase transformation. The root-mean-square (RMS) surface roughness of TiO2 films went from 2.8 to 8.08 nm when the annealing temperature was increased from 300 to 800 °C. Field emission scanning electron microscopy (FESEM) results showed that the TiO2 films’ thickness values fell within the nanometer range (290–310 nm). Based on the results of the tetrazolium dye and trypan blue assays, we found that TiO2 thin films showed no cytotoxicity after the aforementioned culture times at which cell viability was greater than 98%. Independently of the annealing temperature of the TiO2 thin films, the number of CHO-K1 cells on the control substrate and on all TiO2 thin films was greater after 48 or 72 h than it was after 24 h; the highest cell survival rate was observed in TiO2 films annealed at 800 °C. These results indicate that TiO2 thin films do not affect mitochondrial function and proliferation of CHO-K1 cells, and back up the use of TiO2 thin films in biomedical science. PMID:28773740

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

Science.gov (United States)

Cao, Baocheng; Wang, Yuhua; Li, Na; Liu, Bin; Zhang, Yingjie

2013-01-01

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

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

International Nuclear Information System (INIS)

Shishiyanu, S.; Vartic, V.; Shishiyanu, T.; Stratan, Gh.; Rusu, E.; Zarrelli, M.; Giordano, M.

2013-01-01

In this paper we present our experimental results concerning the fabrication of TiO 2 thin films by spray pyrolysis and electrochemical deposition method onto different substrates - Corning glass, Si and optical fibers. The surface morphology of the TiO 2 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 TiO 2 films. (authors)

Visible photoenhanced current-voltage characteristics of Au : TiO2 nanocomposite thin films as photoanodes

International Nuclear Information System (INIS)

Naseri, N; Amiri, M; Moshfegh, A Z

2010-01-01

In this investigation, the effect of annealing temperature and concentration of gold nanoparticles on the photoelectrochemical properties of sol-gel deposited Au : TiO 2 nanocomposite thin films is studied. Various gold concentrations have been added to the TiO 2 thin films and their properties are compared. All the deposited samples are annealed at different temperatures. The optical density spectra of the films show the formation of gold nanoparticles in the films. The optical bandgap energy of the Au : TiO 2 films decreases with increasing Au concentration. The crystalline structure of the nanocomposite films is studied by x-ray diffractometry indicating the formation of gold nanocrystals in the anatase TiO 2 nanocrystalline thin films. X-ray photoelectron spectroscopy reveals that the presence of gold in the metallic state and the formation of TiO 2 are stoichiometric. The photoelectrochemical properties of the Au : TiO 2 samples are characterized using a compartment cell containing H 2 SO 4 and KOH as cathodic and anodic electrolytes, respectively. It is found that the addition of Au nanoparticles in TiO 2 films enhances the photoresponse of the layer and the addition of gold nanocrystals with an optimum value of 5 mol% resulted in the highest photoelectrochemical activity. Moreover, the photoresponse of the samples is also enhanced with an increase in the annealing temperature.

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

Science.gov (United States)

Srivastava, Subodh; Sharma, S. S.; Sharma, Preetam; Sharma, Vinay; Rajura, Rajveer Singh; Singh, M.; Vijay, Y. K.

2014-04-01

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.

Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

International Nuclear Information System (INIS)

Zhao, Wanyu; Fu, Wuyou; Chen, Jingkuo; Li, Huayang; Bala, Hari; Wang, Xiaodong; Sun, Guang; Cao, Jianliang; Zhang, Zhanying

2015-01-01

The composite thin film electrodes were prepared with one-dimensional (1D) TiO 2 -B nanotubes (NTs) and zero-dimensional TiO 2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO 2 NPs electrodes by rational tuning the weight ratio of TiO 2 -B NTs and TiO 2 NPs. When the weight ratio of TiO 2 -B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO 2 -B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO 2 -B NTs and the high surface area of TiO 2 NPs, which has great applied potential in the field of photovoltaic devices. - Highlights: • The composite thin film electrodes (CTFEs) were prepared with nanotubes and nanoparticles. • The CTFEs possess the rapid electron transport and high surface area. • The CTFEs exhibit lower recombination rate and longer electron life time. • The CTFEs have great applied potential in the field of photovoltaic devices

Preparation of Oleyl Phosphate-Modified TiO2/Poly(methyl methacrylate Hybrid Thin Films for Investigation of Their Optical Properties

Directory of Open Access Journals (Sweden)

Masato Fujita

2015-01-01

Full Text Available TiO2 nanoparticles (NPs modified with oleyl phosphate were synthesized through stable Ti–O–P bonds and were utilized to prepare poly(methyl methacrylate- (PMMA- based hybrid thin films via the ex situ route for investigation of their optical properties. After surface modification of TiO2 NPs with oleyl phosphate, IR and 13C CP/MAS NMR spectroscopy showed the presence of oleyl groups. The solid-state 31P MAS NMR spectrum of the product revealed that the signal due to oleyl phosphate (OP shifted upon reaction, indicating formation of covalent Ti–O–P bonds. The modified TiO2 NPs could be homogeneously dispersed in toluene, and the median size was 16.1 nm, which is likely to be sufficient to suppress Rayleigh scattering effectively. The TEM images of TiO2/PMMA hybrid thin films also showed a homogeneous dispersion of TiO2 NPs, and they exhibited excellent optical transparency even though the TiO2 content was 20 vol%. The refractive indices of the OP-modified TiO2/PMMA hybrid thin films changed higher with increases in TiO2 volume fraction, and the hybrid thin film with 20 vol% of TiO2 showed the highest refractive index (n = 1.86.

Undoped TiO2 and nitrogen-doped TiO2 thin films deposited by atomic layer deposition on planar and architectured surfaces for photovoltaic applications

International Nuclear Information System (INIS)

Tian, Liang; Soum-Glaude, Adurey; Volpi, Fabien; Salvo, Luc; Berthomé, Grégory; Coindeau, Stéphane; Mantoux, Arnaud; Boichot, Raphaël; Lay, Sabine; Brizé, Virginie; Blanquet, Elisabeth; Giusti, Gaël; Bellet, Daniel

2015-01-01

Undoped and nitrogen doped TiO 2 thin films were deposited by atomic layer deposition on planar substrates. Deposition on 3D-architecture substrates made of metallic foams was also investigated to propose architectured photovoltaic stack fabrication. All the films were deposited at 265 °C and nitrogen incorporation was achieved by using titanium isopropoxide, NH 3 and/or N 2 O as precursors. The maximum nitrogen incorporation level obtained in this study was 2.9 at. %, resulting in films exhibiting a resistivity of 115 Ω cm (+/−10 Ω cm) combined with an average total transmittance of 60% in the 400–1000 nm wavelength range. Eventually, TiO 2 thin films were deposited on the 3D metallic foam template

Synthesis of photosensitive nanograined TiO2 thin films by SILAR method

International Nuclear Information System (INIS)

Patil, U.M.; Gurav, K.V.; Joo, Oh-Shim; Lokhande, C.D.

2009-01-01

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

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

International Nuclear Information System (INIS)

Barajas-Ledesma, E.; Garcia-Benjume, M.L.; Espitia-Cabrera, I.; Bravo-Patino, A.; Espinoza-Beltran, F.J.; Mostaghimi, J.; Contreras-Garcia, M.E.

2010-01-01

Al 2 O 3 -doped TiO 2 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 Al 2 O 3 -doped TiO 2 film-coated glass substrates were irradiated with visible light before they were introduced in the inoculum. The SEM and EDS results showed that TiO 2 -Al 2 O 3 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 TiO 2 was demonstrated. Al 2 O 3 -doped TiO 2 thin films were successful at eliminating E. coli.

Correlation of Photocatalysis and Photoluminescence Effect in Relation to the Surface Properties of TiO2:Tb Thin Films

Directory of Open Access Journals (Sweden)

Damian Wojcieszak

2013-01-01

Full Text Available In this paper structural, optical, photoluminescence, and photocatalytic properties of TiO2 and TiO2:(2.6 at. % Tb thin films have been compared. Thin films were prepared by high-energy reactive magnetron sputtering process, which enables obtaining highly nanocrystalline rutile structure of deposited films. Crystallites sizes were 8.7 nm and 6.6 nm for TiO2 and TiO2:Tb, respectively. Surface of prepared thin films was homogenous with small roughness of ca. 7.2 and 2.1 nm in case of TiO2 and TiO2:Tb samples, respectively. Optical properties measurements have shown that the incorporation of Tb into TiO2 matrix has not changed significantly the thin films transparency. It also enables obtaining photoluminescence effect in wide range from 350 to 800 nm, what is unique phenomenon in case of TiO2 with rutile structure. Moreover, it has been found that the incorporation of 2.6 at. % of Tb has increased the photocatalytic activity more than two times as compared to undoped TiO2. Additionally, for the first time in the current state of the art, the relationship between photoluminescence effect, photocatalytic activity, and surface properties of TiO2:Tb thin films has been theoretically explained.

Spin Speed and Duration Dependence of TiO2 Thin Films pH Sensing Behavior

Directory of Open Access Journals (Sweden)

Muhammad AlHadi Zulkefle

2016-01-01

Full Text Available Titanium dioxide (TiO2 thin films were applied as the sensing membrane of an extended-gate field-effect transistor (EGFET pH sensor. TiO2 thin films were deposited by spin coating method and the influences of the spin speed and spin duration on the pH sensing behavior of TiO2 thin films were investigated. The spin coated TiO2 thin films were connected to commercial metal-oxide-semiconductor field-effect transistor (MOSFET to form the extended gates and the MOSFET was integrated in a readout interfacing circuit to complete the EGFET pH sensor system. For the spin speed parameter investigation, the highest sensitivity was obtained for the sample spun at 3000 rpm at a fixed spinning time of 60 s, which was 60.3 mV/pH. The sensitivity was further improved to achieve 68 mV/pH with good linearity of 0.9943 when the spin time was 75 s at the speed of 3000 rpm.

Investigation of various properties of HfO2-TiO2 thin film composites deposited by multi-magnetron sputtering system

Science.gov (United States)

Mazur, M.; Poniedziałek, A.; Kaczmarek, D.; Wojcieszak, D.; Domaradzki, J.; Gibson, D.

2017-11-01

In this work the properties of hafnium dioxide (HfO2), titanium dioxide (TiO2) and mixed HfO2-TiO2 thin films with various amount of titanium addition, deposited by magnetron sputtering were described. Structural, surface, optical and mechanical properties of deposited coatings were analyzed. Based on X-ray diffraction and Raman scattering measuremets it was observed that there was a significant influence of titanium concentration in mixed TiO2-HfO2 thin films on their microstructure. Increase of Ti content in prepared mixed oxides coatings caused, e.g. a decrease of average crystallite size and amorphisation of the coatings. As-deposited hafnia and titania thin films exhibited nanocrystalline structure of monoclinic phase and mixed anatase-rutile phase for HfO2 and TiO2 thin films, respectively. Atomic force microscopy investigations showed that the surface of deposited thin films was densely packed, crack-free and composed of visible grains. Surface roughness and the value of water contact angle decreased with the increase of Ti content in mixed oxides. Results of optical studies showed that all deposited thin films were well transparent in a visible light range. The effect of the change of material composition on the cut-off wavelength, refractive index and packing density was also investigated. Performed measurements of mechanical properties revealed that hardness and Young's elastic modulus of thin films were dependent on material composition. Hardness of thin films increased with an increase of Ti content in thin films, from 4.90 GPa to 13.7 GPa for HfO2 and TiO2, respectively. The results of the scratch resistance showed that thin films with proper material composition can be used as protective coatings in optical devices.

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

Institute of Scientific and Technical Information of China (English)

Mehdi Ahmadi; Sajjad Rashidi Dafeh; Samaneh Ghazanfarpour; Mohammad Khanzadeh

2017-01-01

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly (3-hexylthiophene) P3HT:[6-6] phenyl-(6) butyric acid methyl ester (PCBM).1％ vanadium-doped TiO2 nanoparticles were synthesized via the solvothermal method.Crystalline structure,morphology,and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction,scanning electron microscopy,transmittance electron microscopy,and UV-visible transmission spectrum.The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm.The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm.The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm2 compared with its pure counterpart.In the cells using 60 nm pure and vanadium-doped TiO2 layers,the cell using the doped layer showed much higher efficiency.It is remarkable that the extemal quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

Optical and electrical properties of Ti(Cr)O_2:N thin films deposited by magnetron co-sputtering

International Nuclear Information System (INIS)

Kollbek, K.; Szkudlarek, A.; Marzec, M.M.; Lyson-Sypien, B.; Cecot, M.; Bernasik, A.; Radecka, M.; Zakrzewska, K.

2016-01-01

Graphical abstract: - Highlights: • Co-doped well-crystallized stoichiometric Ti(Cr)O_2:N thin films are deposited. • Magnetron sputtering of ceramic TiO_2 target is a new strategy for co-doping. • Bigger contribution from substitutionally incorporated nitrogen is seen in XPS. • Significant red shift of the fundamental absorption edge is obtained. - Abstract: The paper deals with TiO_2-based thin films, doped with Cr and N, obtained by magnetron co-sputtering from titanium dioxide ceramic and chromium targets in Ar + N_2 atmosphere. Co-doped samples of Ti(Cr)O_2:N are investigated from the point of view of morphological, crystallographic, optical, and electrical properties. Characterization techniques such as: X-ray diffraction, XRD, scanning electron microscopy, SEM, atomic force microscopy, AFM, Energy Dispersive X-ray spectroscopy, EDX, X-ray photoelectron spectroscopy, XPS, optical spectrophotometry as well as impedance spectroscopy are applied. XRD reveals TiO_2 and TiO_2:N thin films are well crystallized as opposed to those of TiO_2:Cr and Ti(Cr)O_2:N. XPS spectra confirm that co-doping has been successfully performed with the biggest contribution from the lower binding energy component of N 1s peak at 396 eV. SEM analysis indicates uniform and dense morphology without columnar growth. Comparison between the band gaps indicates a significant shift of the absorption edge towards visible range from 3.69 eV in the case of non-stoichiometric Ti(Cr)O_2_−_x:N to 2.78 eV in the case of stoichiometric Ti(Cr)O_2:N which should be attributed to the incorporation of both dopants at substitutional positions in TiO_2 lattice. Electrical conductivity of stoichiometric Ti(Cr)O_2:N increases in comparison to co-doped nonstoichiometric TiO_2_−_x thin film and reaches almost the same value as that of TiO_2 stoichiometric film.

Annealing effect on the structural, morphological and electrical properties of TiO2/ZnO bilayer thin films

Science.gov (United States)

Khan, M. I.; Imran, S.; Shahnawaz; Saleem, Muhammad; Ur Rehman, Saif

2018-03-01

The effect of annealing temperature on the structural, morphological and electrical properties of TiO2/ZnO (TZ) thin films has been observed. Bilayer thin films of TiO2/ZnO are deposited on FTO glass substrate by spray pyrolysis method. After deposition, these films are annealed at 573 K, 723 K and 873 K. XRD shows that TiO2 is present in anatase phase only and ZnO is present in hexagonal phase. No other phases of TiO2 and ZnO are present. Also, there is no evidence of other compounds like Zn-Ti etc. It also shows that the average grain size of TiO2/ZnO films is increased by increasing annealing temperature. AFM (Atomic force microscope) showed that the average roughness of TiO2/ZnO films is decreased at temperature 573-723 K and then increased at 873 K. The calculated average sheet resistivity of thin films annealed at 573 K, 723 K and 873 K is 152.28 × 102, 75.29 × 102 and 63.34 × 102 ohm-m respectively. This decrease in sheet resistivity might be due to the increment of electron concentration with increasing thickness and the temperature of thin films.

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

International Nuclear Information System (INIS)

Barlier, V.; Bounor-Legare, V.; Alcouffe, P.; Boiteux, G.; Davenas, J.

2007-01-01

New organic-inorganic hybrid thin films based on Poly (9-vinylcarbazole) (P9VK) and Dioxide titanium (TiO 2 ) bulk-heterojunction were obtained by a hydrolysis-condensation (H-C) process of titanium (IV) isopropoxide in thin film. The TiO 2 distribution in the film was investigated by scanning electron microscopy. The results indicated that homogeneous TiO 2 particles around 100 nm were formed on the surface of the polymer thin film. Photoluminescence spectroscopy has been used to study the charge transfer efficiency in the photoactive layer and results were compared with a simplest elaboration route, the dispersion of TiO 2 anatase in a P9VK solution before spin coating. Results showed that TiO 2 elaborated by H-C exhibits a competitive quenching effect with TiO 2 anatase

Magnetic and structural study of Cu-doped TiO2 thin films

International Nuclear Information System (INIS)

Torres, C.E. Rodriguez; Golmar, F.; Cabrera, A.F.; Errico, L.; Navarro, A.M. Mudarra; Renteria, M.; Sanchez, F.H.; Duhalde, S.

2007-01-01

Transparent pure and Cu-doped (2.5, 5 and 10 at.%) anatase TiO 2 thin films were grown by pulsed laser deposition technique on LaAlO 3 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 TiO 2 . 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 TiO 2

Rutile TiO2 thin films grown by reactive high power impulse magnetron sputtering

International Nuclear Information System (INIS)

Agnarsson, B.; Magnus, F.; Tryggvason, T.K.; Ingason, A.S.; Leosson, K.; Olafsson, S.; Gudmundsson, J.T.

2013-01-01

Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 °C. Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing incidence X-ray diffractometry and spectroscopic ellipsometry. Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing. The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 °C. In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300–700 °C. Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7–2.85 at 500 nm. The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing. Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts. - Highlights: • We demonstrate growth of rutile TiO 2 on Si (111) by high power impulse magnetron sputtering. • The films exhibit significantly larger grains than dc magnetron sputtered films • TiO 2 films with high refractive index are obtained without post-growth annealing

Properties of TiO2-based transparent conducting oxide thin films on GaN(0001) surfaces

International Nuclear Information System (INIS)

Kasai, J.; Nakao, S.; Yamada, N.; Hitosugi, T.; Moriyama, M.; Goshonoo, K.; Hoang, N. L. H.; Hasegawa, T.

2010-01-01

Anatase Nb-doped TiO 2 transparent conducting oxide has been formed on GaN(0001) surfaces using a sputtering method. Amorphous films deposited at room temperature were annealed at a substrate temperature of 500 deg. C in vacuum to form single-phase anatase films. Films with a thickness of 170 nm exhibited a resistivity of 8x10 -4 Ω cm with absorptance less than 5% at a wavelength of 460 nm. Furthermore, the refractive index of the Nb-doped TiO 2 was well matched to that of GaN. These findings indicate that Nb-doped TiO 2 is a promising material for use as transparent electrodes in GaN-based light emitting diodes (LEDs), particularly since reflection at the electrode/GaN boundary can be suppressed, enhancing the external quantum efficiency of blue LEDs.

Influence of Nd-Doping on Photocatalytic Properties of TiO2 Nanoparticles and Thin Film Coatings

Directory of Open Access Journals (Sweden)

Damian Wojcieszak

2014-01-01

Full Text Available Structural, optical, and photocatalytic properties of TiO2 and TiO2:Nd nanopowders and thin films composed of those materials have been compared. Titania nanoparticles with 1, 3, and 6 at. % of Nd-dopant were synthesized by sol-gel method. Additionally, thin films with the same material composition were prepared with the aid of spin-coating method. The analysis of structural investigations revealed that all as-prepared nanopowders were nanocrystalline and had TiO2-anatase structure. The average size of crystallites was ca. 4-5 nm and the correlation between the amount of neodymium and the size of TiO2 crystallites was observed. It was shown that the dopant content influenced the agglomeration of the nanoparticles. The results of photocatalytic decomposition of MO showed that doping with Nd (especially in the amount of 3 at. % increased self-cleaning activity of the prepared titania nanopowder. Similar effect was received in case of the thin films, but the decomposition rate was lower due to their smaller active surface area. However, the as-prepared TiO2:Nd photocatalyst in the form of thin films or nanopowders seems to be a very attractive material for various applications.

Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

Science.gov (United States)

Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

2018-01-01

In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

Performance of Erbium-doped TiO2 thin film grown by physical vapor deposition technique

Science.gov (United States)

Lahiri, Rini; Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Chinnamuthu, P.; Mondal, Aniruddha

2017-09-01

Undoped and Erbium-doped TiO2 thin films (Er:TiO2 TFs) were fabricated on the n-type Si substrate using physical vapour deposition technique. Field emission scanning electron microscope showed the morphological change in the structure of Er:TiO2 TF as compared to undoped sample. Energy dispersive X-ray spectroscopy (EDX) confirmed the Er doping in the TiO2 thin film (TF). The XRD and Raman spectrum showed the presence of anatase phase TiO2 and Er2O3 in the Er:TiO2 TF. The Raman scattering depicted additional number of vibrational modes for Er:TiO2 TF due to the presence of Er as compared to the undoped TiO2 TF. The UV-Vis absorption measurement showed that Er:TiO2 TF had approximately 1.2 times more absorption over the undoped TiO2 TF in the range of 300-400 nm. The main band transition, i.e., the transition between the oxygen (2p) state and the Ti (3d) state was obtained at 3.0 eV for undoped TiO2 and at 3.2 eV for Er:TiO2 TF, respectively. The photo responsivity measurement was done on both the detectors, where Er:TiO2 TF detector showed better detectivity ( D *), noise equivalent power and temporal response as compared to undoped detector under ultra-violet illumination.

An impact of the copper additive on photocatalytic and bactericidal properties of TiO2 thin films

Directory of Open Access Journals (Sweden)

Wojcieszak Damian

2017-07-01

Full Text Available The biological and photocatalytic activity of TiO2 and TiO2:Cu in relation to their structure, surface topography, wettability and optical properties of the thin films was investigated. Thin-film coatings were prepared by magnetron sputtering method in oxygen plasma with use of metallic targets (Ti and Ti-Cu. The results of structural studies revealed that addition of Cu into titania matrix (during the deposition process resulted in obtaining of an amorphous film, while in case of undoped TiO2, presence of nanocrystalline anatase (with crystallites size of 20 nm was found. Moreover, an addition of cooper had also an effect on surface diversification and decrease of its hydrophilicity. The roughness of TiO2:Cu film was 25 % lower (0.6 nm as-compared to titania (0.8 nm. These modifications of TiO2:Cu had an impact on the decrease of its photocatalytic activity, probably as a result of the active surface area decrease. Antibacterial and antifungal properties of the thin films against bacteria (Enterococcus hirae, Staphylococcus aureus, Bacillus subtilis, Escherichia coli and yeast (Candida albicans were also examined. For the purpose of this work the method dedicated for the evaluation of antimicrobial properties of thin films was developed. It was revealed that Cu-additive has a positive impact on neutralization of microorganisms.

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

International Nuclear Information System (INIS)

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

2014-01-01

In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO 2 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.

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

International Nuclear Information System (INIS)

Chien, Wen-Chen; Yu, Yang-Yen; Chen, Po-Kan; Yu, Hui-Huan

2011-01-01

In this study, poly(acrylic)/SiO 2 -TiO 2 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 SiO 2 -TiO 2 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 -TiO 2 core-shell nanoparticle hybrid thin films, for potential use in optical applications.

Nanoimprinted distributed feedback lasers comprising TiO2 thin films

DEFF Research Database (Denmark)

Vannahme, Christoph; Smith, Cameron; Leung, Michael C.

2013-01-01

Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass......, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts...

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

International Nuclear Information System (INIS)

Caricato, A.P.; Capone, S.; Ciccarella, G.; Martino, M.; Rella, R.; Romano, F.; Spadavecchia, J.; Taurino, A.; Tunno, T.; Valerini, D.

2007-01-01

The MAPLE technique has been used for the deposition of nanostructured titania (TiO 2 ) nanoparticles thin films to be used for gas sensors applications. An aqueous solution of TiO 2 nanoparticles, synthesised by a novel chemical route, was frozen at liquid nitrogen temperature and irradiated with a pulsed ArF excimer laser in a vacuum chamber. A uniform distribution of TiO 2 nanoparticles with an average size of about 10 nm was deposited on Si and interdigitated Al 2 O 3 substrates as demonstrated by high resolution scanning electron microscopy-field emission gun inspection (SEM-FEG). Energy dispersive X-ray (EDX) analysis revealed the presence of only the titanium and oxygen signals and FTIR (Fourier transform infra-red) revealed the TiO 2 characteristic composition and bond. A comparison with a spin coated thin film obtained from the same solution of TiO 2 nanoparticles is reported. The sensing properties of the films deposited on interdigitated substrates were investigated, too

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

International Nuclear Information System (INIS)

Kumar, D.; Chen, M.S.; Goodman, D.W.

2006-01-01

Ultra-thin TiO 2 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 TiO 2 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 TiO 2 where the Ti atoms are connected via Ti-O-Ti linkages. Based on these assignments, the single Ti 2p 3/2 peak at 455.75 eV observed for the Mo(112)-(8 x 2)-TiO x monolayer film can be assigned to Ti 3+ , consistent with our previous results obtained with high-resolution electron energy loss spectroscopy

Surface nanostructuring of TiO2 thin films by ion beam irradiation

International Nuclear Information System (INIS)

Romero-Gomez, P.; Palmero, A.; Yubero, F.; Vinnichenko, M.; Kolitsch, A.; Gonzalez-Elipe, A.R.

2009-01-01

This work reports a procedure to modify the surface nanostructure of TiO 2 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

Synthesis and electronic properties of Fe2TiO5 epitaxial thin films

Science.gov (United States)

Osada, Motoki; Nishio, Kazunori; Hwang, Harold Y.; Hikita, Yasuyuki

2018-05-01

We investigate the growth phase diagram of pseudobrookite Fe2TiO5 epitaxial thin films on LaAlO3 (001) substrates using pulsed laser deposition. Control of the oxygen partial pressure and temperature during deposition enabled selective stabilization of (100)- and (230)-oriented films. In this regime, we find an optical gap of 2.1 eV and room temperature resistivity in the range of 20-80 Ω cm, which are significantly lower than α-Fe2O3, making Fe2TiO5 potentially an ideal inexpensive visible-light harvesting semiconductor. These results provide a basis to incorporate Fe2TiO5 in oxide heterostructures for photocatalytic and photoelectrochemical applications.

Structural, morphological and optical properties of thermal annealed TiO thin films

International Nuclear Information System (INIS)

Zribi, M.; Kanzari, M.; Rezig, B.

2008-01-01

Structural, morphological and optical properties of TiO thin films grown by single source thermal evaporation method were studied. The films were annealed from 300 to 520 deg. C in air after evaporation. Qualitative film analysis was performed with X-ray diffraction, atomic force microscopy and optical transmittance and reflectance spectra. A correlation was established between the optical properties, surface roughness and growth morphology of the evaporated TiO thin films. The X-ray diffraction spectra indicated the presence of the TiO 2 phase for the annealing temperature above 400 deg. C

Effect of iron doping on structural and optical properties of TiO2 thin film by sol–gel routed spin coating technique

Directory of Open Access Journals (Sweden)

Stephen Lourduraj

2017-08-01

Full Text Available Thin films of iron (Fe-doped titanium dioxide (Fe:TiO2 were prepared by sol–gel spin coating technique and further calcined at 450∘C. The structural and optical properties of Fe-doped TiO2 thin films were investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, ultraviolet–visible spectroscopy (UV–vis and atomic force microscopic (AFM techniques. The XRD results confirm the nanostructured TiO2 thin films having crystalline nature with anatase phase. The characterization results show that the calcined thin films having high crystallinity and the effect of iron substitution lead to decreased crystallinity. The SEM investigations of Fe-doped TiO2 films also gave evidence that the films were continuous spherical shaped particles with a nanometric range of grain size and film was porous in nature. AFM analysis establishes that the uniformity of the TiO2 thin film with average roughness values. The optical measurements show that the films having high transparency in the visible region and the optical band gap energy of Fe-doped TiO2 film with iron (Fe decrease with increase in iron content. These important requirements for the Fe:TiO2 films are to be used as window layers in solar cells.

The Effect of Film Thickness on the Gas Sensing Properties of Ultra-Thin TiO2 Films Deposited by Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Rachel L. Wilson

2018-03-01

Full Text Available Analyte sensitivity for gas sensors based on semiconducting metal oxides should be highly dependent on the film thickness, particularly when that thickness is on the order of the Debye length. This thickness dependence has previously been demonstrated for SnO2 and inferred for TiO2. In this paper, TiO2 thin films have been prepared by Atomic Layer Deposition (ALD using titanium isopropoxide and water as precursors. The deposition process was performed on standard alumina gas sensor platforms and microscope slides (for analysis purposes, at a temperature of 200 °C. The TiO2 films were exposed to different concentrations of CO, CH4, NO2, NH3 and SO2 to evaluate their gas sensitivities. These experiments showed that the TiO2 film thickness played a dominant role within the conduction mechanism and the pattern of response for the electrical resistance towards CH4 and NH3 exposure indicated typical n-type semiconducting behavior. The effect of relative humidity on the gas sensitivity has also been demonstrated.

Thickness Dependent Optical Properties of Sol-gel based MgF2 – TiO2 Thin Films

Directory of Open Access Journals (Sweden)

Siddarth Krishnaraja Achar

2018-04-01

Full Text Available MgF2 – TiO2 thin films were prepared by cost effective solgel technique onto glass substrates and optical parameters were determined by envelope technique. Thin films were characterized by optical transmission spectroscopy in the spectral range 290 – 1000 nm. The refractive index, extinction coefficient, Optical thickness and band gap dependency on thickness were evaluated. Thickness dependency of thin films showed direct allowed transition with band gap of 3.66 to 3.73 eV.

Growth of TiO2 Thin Film on Various Substrates using RF Magnetron Sputtering

International Nuclear Information System (INIS)

Ali, Riyaz Ahmad Mohamed; Nayan, Nafarizal

2011-01-01

The conductivity of Titanium Dioxide (TiO 2 ) thin film fabricated using Radio Frequency (RF) Magnetron Sputtering on Silicon (Si), Indium doped--Tin Oxide (ITO) and microscope glass (M) substrates is presented in this paper. The dependant of thin film thickness and type of substrate been discussed. TiO 2 was deposited using Ti target in Ar+O 2 (45:10) mixture at 250 W for 45, 60, 75, 90, 105 and 120 minute. Resultant thickness varies from 295 nm to 724 nm with deposition rate 6.4 nm/min. On the other hand, resistivity, Rs value for ITO substrate is between 5.72x10 -7 to 1.54x10 -6 Ω.m, Si substrate range is between 3.52x10 -6 to 1.76x10 -5 Ω.m and M substrate range is between 99 to 332 Ω.m. The value of resistivity increases with the thickness of the thin film.

Influence of nanocrystalline structure and surface properties of TiO2 thin films on the viability of L929 cells

Directory of Open Access Journals (Sweden)

Osękowska Małgorzata

2015-09-01

Full Text Available In this work the physicochemical and biological properties of nanocrystalline TiO2 thin films were investigated. Thin films were prepared by magnetron sputtering method. Their properties were examined by X-ray diffraction, photoelectron spectroscopy, atomic force microscopy, optical transmission method and optical profiler. Moreover, surface wettability and scratch resistance were determined. It was found that as-deposited coatings were nanocrystalline and had TiO2-anatase structure, built from crystallites in size of 24 nm. The surface of the films was homogenous, composed of closely packed grains and hydrophilic. Due to nanocrystalline structure thin films exhibited good scratch resistance. The results were correlated to the biological activity (in vitro of thin films. Morphological changes of mouse fibroblasts (L929 cell line after contact with the surface of TiO2 films were evaluated with the use of a contrast-phase microscope, while their viability was tested by MTT colorimetric assay. The viability of cell line upon contact with the surface of nanocrystalline TiO2 film was comparable to the control sample. L929 cells had homogenous cytoplasm and were forming a confluent monofilm, while lysis and inhibition of cell growth was not observed. Moreover, the viability in contact with surface of examined films was high. This confirms non-cytotoxic effect of TiO2 film surface on mouse fibroblasts.

Nanocrystalline Pt-doped TiO2 thin films prepared by spray pyrolysis ...

Indian Academy of Sciences (India)

Administrator

Spray pyrolysis techniques; TiO2 thin films; hydrogen gas response. 1. Introduction ... tion is necessary during the production, storage and use of hydrogen. It is also ..... ient, and 'green': it may be used to large scale industrial application for ...

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.

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m respectively, according to four point probe. Keywords: TiO2, Diode laser, XRD, SEM

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.

Chromium doped TiO2 sputtered thin films synthesis, physical investigations and applications

CERN Document Server

Hajjaji, Anouar; Gaidi, Mounir; Bessais, Brahim; El Khakani, My Ali

2014-01-01

This book presents co-sputtered processes ways to produce chrome doped TiO2 thin films onto various substrates such as quartz, silicon and porous silicon. Emphasis is given on the link between the experimental preparation and physical characterization in terms of Cr content. Moreover, the structural, optical and optoelectronic investigations are emphasized throughout. The book explores the potencial applications of devices based on Cr doped TiO2 thin films as gas sensors and in photocatalysis and in the photovoltaic industry. Also, this book provides extensive leads into research literature, and each chapter contains details which aim to develop awareness of the subject and the methods used. The content presented here will be useful for graduate students as well as researchers in materials science, physics, chemistry and engineering.

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

International Nuclear Information System (INIS)

Wei Yaowei; Liu Hao; Sheng Ouyang; Liu Zhichao; Chen Songlin; Yang Liming

2011-01-01

Research on thin film deposited by atomic layer deposition (ALD) for laser damage resistance is rare. In this paper, it has been used to deposit TiO 2 /Al 2 O 3 films at 110 deg. C and 280 deg. C on fused silica and BK7 substrates. Microstructure of the thin films was investigated by x-ray diffraction. The laser-induced damage threshold (LIDT) of samples was measured by a damage test system. Damage morphology was studied under a Nomarski differential interference contrast microscope and further checked under an atomic force microscope. Multilayers deposited at different temperatures were compared. The results show that the films deposited by ALD had better uniformity and transmission; in this paper, the uniformity is better than 99% over 100 mm Φ samples, and the transmission is more than 99.8% at 1064 nm. Deposition temperature affects the deposition rate and the thin film microstructure and further influences the LIDT of the thin films. As to the TiO 2 /Al 2 O 3 films, the LIDTs were 6.73±0.47 J/cm 2 and 6.5±0.46 J/cm 2 at 110 deg. C on fused silica and BK7 substrates, respectively. The LIDTs at 110 deg. C are notably better than 280 deg. C.

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

Science.gov (United States)

Khan, M. I.; Ali, Asghar

TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW) diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m) respectively, according to four point probe.

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

Science.gov (United States)

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

2008-11-01

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

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.

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

International Nuclear Information System (INIS)

Agus Santoso; Tjipto Sujitno; Sayono

2002-01-01

It has been fabricated and characterization a TiO 2 thin films deposited on glass substrate using DC sputtering technique. Fabrication of TiO 2 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 o C, 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 TiO 2 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 o C and deposition time 2.5 hours was anatase with orientation (001) and (200). (author)

Structural, Electrical and Optical Properties of TiO2 Thin Film Deposited on the Nano Porous Silicon Template

Science.gov (United States)

Bahar, Mahmood; Dermani, Ensieh Khalili

The porous silicon (PSi), which is produced by the electrochemical etching, has been used as a substrate for the growth of the titanium oxide (TiO2) thin films. By using the EBPVD method, TiO2 thin films have been deposited on the surface of the PSi substrate. TiO2/PSi layers were annealed at the temperature of 400∘C, 500∘C and 600∘C for different tests. The morphology and structures of layers were investigated by the scanning electron microscopy (SEM) and X-ray diffraction (XRD). The current-voltage characteristic curves of samples and the ideality factor of heterojunction were studied. The results showed that the electrical properties of the samples change with increase in the annealing temperature. The optical properties of the prepared samples were investigated by using UV-Vis and photoluminescence (PL) spectroscopy. Green light emission of the PSi combined with the blue light and violet-blue emission obtained from the TiO2/PSi PL spectra. The results showed that the optical band gap energy of the PSi has increased from 1.86eV to 2.93eV due to the deposition of TiO2 thin film.

Surface Modification of Aerosol-Assisted CVD Produced TiO2 Thin Film for Dye Sensitised Solar Cell

Directory of Open Access Journals (Sweden)

SuPei Lim

2014-01-01

Full Text Available We report a simple and convenient method for the preparation of Ag/TiO2 thin films supported on indium tin oxide, which was achieved by sonochemical deposition of Ag+ on aerosol-assisted chemical vapour deposited TiO2 thin films. Posttreatment was performed on the film by immersion in HCl. The as-prepared composite film was characterised by X-ray diffraction, ultraviolet-visible absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy. The photoelectrochemical measurements and J-V characterisation showed approximately fivefold increase in photocurrent density generation and approximately sevenfold enhancement in dye sensitiser solar cell (DSSC conversion efficiency, which was achieved after modification of the TiO2 film with HCl posttreatment and Ag particle deposition. The improved photocurrent density of 933.30 μA/cm2, as well as DSSC power conversion efficiency of 3.63% with high stability, is an indication that the as-synthesised thin film is a potential candidate for solar energy conversion applications.

Synthesis of nanocrystalline TiO 2 thin films by liquid phase ...

Indian Academy of Sciences (India)

A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully deposited on a glass substrate at 30°C from an aqueous solution of TiO2–HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction ...

Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

NARCIS (Netherlands)

Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

2015-01-01

We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to

Self-organized nanocrack networks: a pathway to enlarge catalytic surface area in sputtered ceramic thin films, showcased for photocatalytic TiO2

Science.gov (United States)

Henkel, B.; Vahl, A.; Aktas, O. C.; Strunskus, T.; Faupel, F.

2018-01-01

Sputter deposited photocatalytic thin films offer high adherence and mechanical stability, but typically are outperformed in their photocatalytic properties by colloidal TiO2 nanostructures, which in turn typically suffer from problematic removal. Here we report on thermally controlled nanocrack formation as a feasible and batch applicable approach to enhance the photocatalytic performance of well adhering, reactively sputtered TiO2 thin films. Networks of nanoscopic cracks were induced into tailored columnar TiO2 thin films by thermal annealing. These deep trenches are separating small bundles of TiO2 columns, adding their flanks to the overall catalytically active surface area. The variation of thin film thickness reveals a critical layer thickness for initial nanocrack network formation, which was found to be about 400 nm in case of TiO2. The columnar morphology of the as deposited TiO2 layer with weak bonds between respective columns and with strong bonds to the substrate is of crucial importance for the formation of nanocrack networks. A beneficial effect of nanocracking on the photocatalytic performance was experimentally observed. It was correlated by a simple geometric model for explaining the positive impact of the crack induced enlargement of active surface area on photocatalytic efficiency. The presented method of nanocrack network formation is principally not limited to TiO2 and is therefore seen as a promising candidate for utilizing increased surface area by controlled crack formation in ceramic thin films in general.

Optical, Electrical, and Crystal Properties of TiO2 Thin Films Grown by Atomic Layer Deposition on Silicon and Glass Substrates

Science.gov (United States)

Kupa, I.; Unal, Y.; Cetin, S. S.; Durna, L.; Topalli, K.; Okyay, A. K.; Ates, H.

2018-05-01

TiO2 thin films have been deposited on glass and Si(100) by atomic layer deposition (ALD) technique using tetrakis(diethylamido)titanium(IV) and water vapor as reactants. Thorough investigation of the properties of the TiO2/glass and TiO2/Si thin films was carried out, varying the deposition temperature in the range from 100°C to 250°C while keeping the number of reaction cycles fixed at 1000. Physical and material property analyses were performed to investigate optical and electrical properties, composition, structure, and morphology. TiO2 films grown by ALD may represent promising materials for future applications in optoelectronic devices.

Transparent TiO2 nanowire networks via wet corrosion of Ti thin films for dye-sensitized solar cells

Science.gov (United States)

Shin, Eunhye; Jin, Saera; Hong, Jongin

2017-09-01

Transparent TiO2 nanowire networks were prepared by corrosion of Ti thin films on F-doped SnO2 glass substrates in an alkaline (potassium hydroxide: KOH) solution. The formation of the porous TiO2 nanostructures from the Ti thin films was thoroughly investigated. Dye-sensitized solar cells with a photoanode of 1.2-μm-thick nanowire networks exhibit an average optical transmittance of 40% in the visible light region and a power conversion efficiency of 1.0% under one sun illumination.

Ion beam modification of TiO2 films prepared by Cat-CVD for solar cell

International Nuclear Information System (INIS)

Narita, Tomoki; Iida, Tamio; Ogawa, Shunsuke; Mizuno, Kouichi; So, Jisung; Kondo, Akihiro; Yoshida, Norimitsu; Itoh, Takashi; Nonomura, Shuichi; Tanaka, Yasuhito

2008-01-01

The effects of nitrogen ion bombardment on TiO 2 films prepared by the Cat-CVD method have been studied to improve the optical and electrical properties of the material for use in Si thin film solar cells. The refractive index n and the dark conductivity of the TiO 2 film increased with irradiation time. The refractive index n of the TiO 2 film was changed from 2.1 to 2.4 and the electrical conductivity was improved from 3.4 x 10 -2 to 1.2 x 10 -1 S/cm by the irradiation. These results are due to the formation of Ti-N bonds and oxygen vacancies in the film

Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

OpenAIRE

Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

2015-01-01

We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx

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

International Nuclear Information System (INIS)

Caricato, A.P.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Spadavecchia, J.; Tunno, T.; Valerini, D.

2007-01-01

We report morphological and optical properties of a colloidal TiO 2 nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1 μm in size was noticed. Form UV-vis transmission spectra, recorded in the 200-800 nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO 2 nanoparticle thin films

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

International Nuclear Information System (INIS)

Tian, F.

2001-01-01

TiO 2 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 TiO 2 thin film preparation, mainly by CVD, and about PEC and PC destruction of organic effluents by TiO 2 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 TiO 2 films deposited by LPCVD on SnO 2 coated glass using either TTIP or TTB precursors in the presence of O 2 , 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 TiO 2 films prepared by anodisation of titanium mesh was studied and the results are presented in Chapter 5. PEC or PC destruction of MPA, RDX and 4-CP have been studied using TiO 2 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

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

International Nuclear Information System (INIS)

Gyoergy, E; Pino, A Perez del; Sauthier, G; Figueras, A; Alsina, F; Pascual, J

2007-01-01

Titanium dioxide (TiO 2 ) thin films were synthesized on (1 0 0) Si substrates by reactive pulsed laser deposition (PLD) technique. A frequency quadrupled Nd : YAG (λ = 266 nm, τ FWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of metallic Ti targets. The experiments were performed in controlled oxygen atmosphere. Crystallinity, surface morphology and local electric properties of the obtained oxide thin films were investigated by x-ray diffractometry, micro-Raman spectroscopy and current sensing atomic force microscopy. An inter-relation was found between the surface morphology, the crystalline structure and the nano-scale electric properties which open the possibility of synthesizing by the PLD technique TiO 2 thin films with tunable functional properties for future applications such as photocatalysts, gas sensors or solar energy converters

Photoelectrocatalytic Degradation of Sodium Oxalate by TiO2/Ti Thin Film Electrode

Directory of Open Access Journals (Sweden)

Chen-Yu Chang

2012-01-01

Full Text Available The photocatalytically active TiO2 thin film was deposited on the titanium substrate plate by chemical vapor deposition (CVD method, and the photoelectrocatalytic degradation of sodium oxalate was investigated by TiO2 thin film reactor prepared in this study with additional electric potential at 365 nm irradiation. The batch system was chosen in this experiment, and the controlled parameters were pH, different supporting electrolytes, applied additional potential, and different electrolyte solutions that were examined and discussed. The experimental results revealed that the additional applied potential in photocatalytic reaction could prohibit recombination of electron/hole pairs, but the photoelectrocatalytic effect was decreased when the applied electric potential was over 0.25 V. Among the electrolyte solutions added, sodium sulfate improved the photoelectrocatalytic effect most significantly. At last, the better photoelectrocatalytic degradation of sodium oxalate occurred at pH 3 when comparing the pH influence.

A Humidity Sensor Based on Nb-doped Nanoporous TiO2 Thin Film

Directory of Open Access Journals (Sweden)

Mansoor Anbia

2011-11-01

Full Text Available The humidity sensing properties of the sensor fabricated from Nb-doped nanoporous TiO2 by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes have been investigated. The nanoporous thin film has been prepared by sol-gel technique. The product has been characterized by X-ray diffraction and scanning electron microscopy to analyze the structure and its morphology. It is found that the impedance of this sensor changes more than four orders of magnitude in the relative humidity (RH range of 11–95 % at 25 °C. The response and recovery time of the sensor are about 19 and 25 s, respectively, during the RH variation from 11 to 95 %. The sensor shows high humidity sensitivity, rapid response and recovery, prominent stability, good repeatability and narrow hysteresis loop. These results indicate that Nb-doped nanoporous TiO2 thin films have a great potential for humidity sensing applications in room temperature operations.

ALD TiO2 thin film as dielectric for Al/p-Si Schottky diode

Indian Academy of Sciences (India)

Abstract. Electrical analysis of Al/p-Si Schottky diode with titanium dioxide (TiO2) thin film was performed at ..... This work was partially supported by The Management Unit of Scientific Research Project of Bozok University and Hitit. University.

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.

A weak-light-responsive TiO2/g-C3N4 composite film: photocatalytic activity under low-intensity light irradiation.

Science.gov (United States)

Wang, Peifang; Guo, Xiang; Rao, Lei; Wang, Chao; Guo, Yong; Zhang, Lixin

2018-05-10

A TiO 2 /g-C 3 N 4 composite photocatalytic film was prepared by in situ synthesis method and its photocatalytic capability under weak-visible-light condition was studied. The co-precursor with different ratio of melamine and TiO 2 sol-gel precursor were treated using ultrasonic mixing, physical deposition, and co-sintering method to form the smooth, white-yellow, and compact TiO 2 /g-C 3 N 4 composite films. The prepared TiO 2 /g-C 3 N 4 materials were characterized by SEM, TEM, EDS, XRD, BET, VBXPS, and UV-vis diffuse reflectance spectra. The results of composite showed that TiO 2 and g-C 3 N 4 have close interfacial connections which are favorable to charge transfer between these two semiconductors with suitable band structure, g-C 3 N 4 retard the anatase-to-rutile phase transition of TiO 2 significantly, the specific surface area were increased with g-C 3 N 4 ratio raised. Under weak-light irradiation, composite films photocatalytic experiments exhibited RhB removal efficiency approaching 90% after three recycles. Powders suspension degradation experiments revealed the removal efficiency of TiO 2 /g-C 3 N 4 (90.8%) was higher than pure TiO 2 (52.1%) and slightly lower than pure g-C 3 N 4 (96.6%). By control experiment, the enhanced photocatalysis is ascribed to the combination of TiO 2 and g-C 3 N 4 , which not only produced thin films with greater stability but also formed heterojunctions that can be favorable to charge transfer between these two semiconductors with suitable band structure. This study presents the potential application of photocatalytic film in the wastewater treatment under weak-light situation.

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Science.gov (United States)

Lan, Chunfeng; Luo, Jingting; Lan, Huabin; Fan, Bo; Peng, Huanxin; Zhao, Jun; Sun, Huibin; Zheng, Zhuanghao; Liang, Guangxing; Fan, Ping

2018-01-01

We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE) increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc), short-circuit current (Jsc) and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells. PMID:29495612

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Directory of Open Access Journals (Sweden)

Chunfeng Lan

2018-02-01

Full Text Available We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc, short-circuit current (Jsc and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells.

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

International Nuclear Information System (INIS)

Cavalheiro, A.A.; Bruno, J.C.; Saeki, M.J.; Valente, J.P.S.; Florentino, A.O.

2008-01-01

The effects of silver insertion on the TiO 2 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 TiO 2 thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO 2 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 mg C 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

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

International Nuclear Information System (INIS)

Valaski, R.; Yamamoto, N.A.D.; Canestraro, C.D.; Micaroni, L.; Mello, R.M.Q.; Quirino, W.G.; Legani, C.; Achete, C.A.; Roman, L.S.; Cremona, M.

2010-01-01

In this work, the influence of titanium dioxide (TiO 2 ) thin films on the efficiency of organic photovoltaic devices based on electrochemically synthesized polythiophene (PT) was investigated. TiO 2 films were produced by sol-gel methods with controlled thickness. The best TiO 2 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 TiO 2 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 (λ = 610 nm; 1 W/m 2 ) that is three orders of magnitude higher than that presented by PT-homolayer devices with similar PT thickness. In addition, the open-circuit voltage (V oc ) was about 700 mV and the short-circuit current density (J sc ) was 0.03 A/m 2 (λ = 610 nm; 7 W/m 2 ). However, as for the PT-homolayer also the TiO 2 /PT based devices are characterized by antibatic response when illuminated through FTO. Finally, the Fill Factor (FF) of these devices is low (25%), indicating that the series resistance (R s ), which is strongly dependent of the PT thickness, is too large. This large R s value is compensated by TiO 2 /PT interface morphology and by FTO/TiO 2 and TiO 2 /PT interface phenomena producing preferential paths in which the internal electrical field is higher, improving the device efficiency.

Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

OpenAIRE

Duarte, D. A.; Massi, M.; da Silva Sobrinho, A. S.

2014-01-01

In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototype...

Structural Modification of Sol-Gel Synthesized V2O5 and TiO2 Thin Films with/without Erbium Doping

Directory of Open Access Journals (Sweden)

Fatma Pınar Gökdemir

2014-01-01

Full Text Available Comparative work of with/without erbium- (Er- doped vanadium pentoxide (V2O5 and titanium dioxide (TiO2 thin films were carried out via sol-gel technique by dissolving erbium (III nitrate pentahydrate (Er(NO33·5H2O in vanadium (V oxoisopropoxide (OV[OCH(CH32]3 and titanium (IV isopropoxide (Ti[OCH(CH32]4. Effect of Er doping was traced by Fourier transform IR (FTIR, thermogravimetric/differential thermal (TG/DTA, and photoluminescence measurements. UV-Vis transmission/absorption measurement indicated a blue shift upon Er doping in V2O5 film due to the softening of V=O bond while appearance of typical absorption peaks in Er-doped TiO2 film. Granule size of the films increased (reduced upon Er substitution on host material compared to undoped V2O5 and TiO2 films, respectively.

Synthesis, characterization and application of Co doped TiO2 multilayer thin films

Science.gov (United States)

Khan, M. I.

2018-06-01

To use the visible portion of solar light, 2% cobalt doped TiO2 (Co: TiO2) multilayer thin films having 1, 2, 3 and 4 stacked layers have been deposited on FTO substrates using spray pyrolysis technique. XRD results show that 1 and 2 layers of films have anatase phase. Brookite phase has been appeared at the 3 and 4 layered films. The average grain size of 1, 2, 3 and 4 layers of films are 14.4, 23.5, 29.7 and 33.6 nm respectively. UV-Vis results show that 4th layer film has high absorption in the visible region. The calculated Eg of 1, 2, 3 and 4 layers is 3.54, 3.42, 3.30 and 3.03 eV respectively. The calculated average sheet resistivity of 1, 2, 3 and 4 layers of films is 7.68 × 104, 4.54 × 104, 8.85 × 103 and 7.95 × 102 (ohm-m) respectively, according to four point probe technique. Solar simulator results show that highest solar conversion efficiency (5.6%) has been obtained by using 3 stacked layers photoanode. This new structure in the form of stack layers provides a way to improve the efficiency of optoelectronic devices.

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

International Nuclear Information System (INIS)

Medina-Valtierra, Jorge; Garcia-Servin, Josafat; Frausto-Reyes, Claudio; Calixto, Sergio

2006-01-01

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

Thin-Film Photoluminescent Properties and the Atomistic Model of Mg2TiO4 as a Non-rare Earth Matrix Material for Red-Emitting Phosphor

Science.gov (United States)

Huang, Chieh-Szu; Chang, Ming-Chuan; Huang, Cheng-Liang; Lin, Shih-kang

2016-12-01

Thin-film electroluminescent devices are promising solid-state lighting devices. Red light-emitting phosphor is the key component to be integrated with the well-established blue light-emitting diode chips for stimulating natural sunlight. However, environmentally hazardous rare-earth (RE) dopants, e.g. Eu2+ and Ce2+, are commonly used for red-emitting phosphors. Mg2TiO4 inverse spinel has been reported as a promising matrix material for "RE-free" red light luminescent material. In this paper, Mg2TiO4 inverse spinel is investigated using both experimental and theoretical approaches. The Mg2TiO4 thin films were deposited on Si (100) substrates using either spin-coating with the sol-gel process, or radio frequency sputtering, and annealed at various temperatures ranging from 600°C to 900°C. The crystallinity, microstructures, and photoluminescent properties of the Mg2TiO4 thin films were characterized. In addition, the atomistic model of the Mg2TiO4 inverse spinel was constructed, and the electronic band structure of Mg2TiO4 was calculated based on density functional theory. Essential physical and optoelectronic properties of the Mg2TiO4 luminance material as well as its optimal thin-film processing conditions were comprehensively reported.

Preparation and optical properties of mesoporous TiO2 thin films by a two-step sol-gel technique

International Nuclear Information System (INIS)

Kartini, I.; Lu, G.Q.; Meredith, P.; Zhao, X.S.

2002-01-01

This paper concerns the preparation of mesoporous titania nanopowders and thin films for use in next generation photoelectrochemical solar cells. We have recently developed a novel method for preparing mesoporous TiO 2 powders using a Two-Step Sol-gel method (TSS). These materials have crystalline domains characteristic of anatase. The first step of the process involves the hydrolysis of titanium isopropoxide in a basic aqueous solution mediated by neutral surfactant. The solid product resulting from Step-1 is then treated in acidified ethanol solution containing a titanium precursor to yield anatase TiO 2 . The resultant powder exhibits a high surface area and large pore volume with uniform mesopores. Slurries made from the resultant powder of Steps 1 and 2 have been used to produce thin titania films on glass slides. The optical and structural properties of these films have been compared to the films made of a commercial titania (Degussa P25, BASF). We will discuss these properties with respect to the possible use of such mesoporous titania films as the wide band gap semiconductor in dye-sensitized nanocrystalline TiO 2 solar cells

Influence of Pore Size on the Optical and Electrical Properties of Screen Printed TiO2 Thin Films

Directory of Open Access Journals (Sweden)

Dinfa Luka Domtau

2016-01-01

Full Text Available Influence of pore size on the optical and electrical properties of TiO2 thin films was studied. TiO2 thin films with different weight percentages (wt% of carbon black were deposited by screen printing method on fluorine doped tin oxide (FTO coated on glass substrate. Carbon black decomposed on annealing and artificial pores were created in the films. All the films were 3.2 µm thick as measured by a surface profiler. UV-VIS-NIR spectrophotometer was used to study transmittance and reflectance spectra of the films in the photon wavelength of 300–900 nm while absorbance was studied in the range of 350–900 nm. Band gaps and refractive index of the films were studied using the spectra. Reflectance, absorbance, and refractive index were found to increase with concentrations of carbon black. There was no significant variation in band gaps of films with change in carbon black concentrations. Transmittance reduced as the concentration of carbon black in TiO2 increased (i.e., increase in pore size. Currents and voltages (I-V characteristics of the films were measured by a 4-point probe. Resistivity (ρ and conductivity (σ of the films were computed from the I-V values. It was observed that resistivity increased with carbon black concentrations while conductivity decreased as the pore size of the films increased.

Intrinsic Photocatalytic Assessment of Reactively Sputtered TiO2 Films

NARCIS (Netherlands)

Rafieian Boroujeni, Damon; Driessen, Rick Theodorus; Driessen, Rick T.; Ogieglo, Wojciech; Lammertink, Rob G.H.

2015-01-01

Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during

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

International Nuclear Information System (INIS)

Abu Kassim, N.F.; Ku Hamid, K.H.; Azizan, A.

2006-01-01

Solar photo catalytic degradation of the textile industry wastewater using TiO 2 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. TiO 2 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)

Development of Dye-Sensitized Solar Cells with Sputtered N-Doped TiO2 Thin Films: From Modeling the Growth Mechanism of the Films to Fabrication of the Solar Cells

Directory of Open Access Journals (Sweden)

D. A. Duarte

2014-01-01

Full Text Available In this paper, nitrogen-doped TiO2 thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the TiO2 were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototypes was investigated by current-voltage relations measured under illuminated and dark conditions. The results indicate that, during the film deposition, the control of the oxidation processes of the nitride layers plays a fundamental role for an effective incorporation of substitutional nitrogen in the film structure and cells built with nitrogen-doped TiO2 have higher short-circuit photocurrent in relation to that obtained with conventional DSSCs. On the other hand, DSSCs built with nondoped TiO2 have higher open-circuit voltage. These experimental observations indicate that the incorporation of nitrogen in the TiO2 lattice increases simultaneously the processes of generation and destruction of electric current.

SURFACE MODIFICATION OF SEMICONDUCTOR THIN FILM OF TiO2 ON GRAPHITE SUBSTRATE BY Cu-ELECTRODEPOSITION

Directory of Open Access Journals (Sweden)

Fitria Rahmawati

2010-06-01

Full Text Available Surface modification of graphite/TiO2 has been done by mean of Cu electrodeposition. This research aims to study the effect of Cu electrodeposition on photocatalytic enhancing of TiO2. Electrodeposition has been done using CuSO4 0,4 M as the electrolyte at controlled current. The XRD pattern of modified TiO2 thin film on graphite substrate exhibited new peaks at 2θ= 43-44o and 2θ= 50-51o that have been identified as Cu with crystal cubic system, face-centered crystal lattice and crystallite size of 26-30 nm. CTABr still remains in the material as impurities. Meanwhile, based on morphological analysis, Cu particles are dissipated in the pore of thin film. Graphite/TiO2/Cu has higher photoconversion efficiency than graphite/TiO2.   Keywords: semiconductor, graphite/TiO2, Cu electrodeposition

Influence of surfactant and annealing temperature on optical properties of sol-gel derived nano-crystalline TiO2 thin films.

Science.gov (United States)

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

2010-03-01

Titanium dioxide thin films have been synthesized by sol-gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 degrees C. The influence of surfactant and annealing temperature on optical properties of TiO(2) thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO(2) films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO(2) films was estimated by Tauc's method at different annealing temperature. Copyright 2010 Elsevier B.V. All rights reserved.

Strategies to prepare TiO2 thin films, doped with transition metal ions, that exhibit specific physicochemical properties to support osteoblast cell adhesion and proliferation

International Nuclear Information System (INIS)

Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Pandey, Ravi Ranjan; Kar, Satabisha; Saini, Krishan Kumar; Pande, Gopal

2014-01-01

Metal ion doped titanium oxide (TiO 2 ) thin films, as bioactive coatings on metal or other implantable materials, can be used as surfaces for studying the cell biological properties of osteogenic and other cell types. Bulk crystallite phase distribution and surface carbon–oxygen constitution of thin films, play an important role in determining the biological responses of cells that come in their contact. Here we present a strategy to control the polarity of atomic interactions between the dopant metal and TiO 2 molecules and obtain surfaces with smaller crystallite phases and optimal surface carbon–oxygen composition to support the maximum proliferation and adhesion of osteoblast cells. Our results suggest that surfaces, in which atomic interactions between the dopant metals and TiO 2 were less polar, could support better adhesion, spreading and proliferation of cells. - Highlights: • Electrochemical properties of dopants control the nature of TiO 2 thin films. • A model explains the correlation of dopant properties and behaviour of TiO 2 films. • Dopants with less polar interaction with TiO 2 exhibit better biological activity

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

Science.gov (United States)

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

2013-07-23

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

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

International Nuclear Information System (INIS)

Singh, Preetam; Kaur, Davinder

2010-01-01

We report, the structural and optical properties of nanocrystalline anatase TiO 2 thin films grown on glass substrate by dc magnetron sputtering at room temperature. The influence of sputtering power and pressure over crystallinity and surface morphology of the films were investigated. It was observed that increase in sputtering power activates the TiO 2 film growth from relative lower surface free energy to higher surface free energy. XRD pattern revealed the change in preferred orientation from (1 0 1) to (0 0 4) with increase in sputtering power, which is accounted for different surface energy associated with different planes. Microstructure of the films also changes from cauliflower type to columnar type structures with increase in sputtering power. FESEM images of films grown at low pressure and low sputtering power showed typical cauliflower like structure. The optical measurement revealed the systematic variation of the optical constants with deposition parameters. The films are highly transparent with transmission higher than 90% with sharp ultraviolet cut off. The transmittance of these films was found to be influenced by the surface roughness and film thickness. The optical band gap was found to decrease with increase in the sputtering power and pressure. The refractive index of the films was found to vary in the range of 2.50-2.24 with increase in sputtering pressure or sputtering power, resulting in the possibility of producing TiO 2 films for device applications with different refractive index, by changing the deposition parameters.

Studies on the performance of TiO2 thin films as protective layer to chlorophyll in Ocimum tenuiflorum L from UV radiation

International Nuclear Information System (INIS)

Malliga, P.; Selvi, B. Karunai; Pandiarajan, J.; Prithivikumaran, N.; Neyvasagam, K.

2015-01-01

Thin films of TiO 2 were prepared on glass substrates using sol-gel dip coating technique. The films with 10 coatings were prepared and annealed at temperatures 350°C, 450°C and 550°C for 1 hour in muffle furnace. The annealed films were characterized by X – Ray diffraction (XRD), UV – Visible, AFM, Field Effect Scanning Electron Microscopy (FESEM) and EDAX studies. Chlorophyll has many health benefits due to its structural similarity to human blood and its good chelating ability. It has antimutagenic and anticarcinogenic properties. UV light impairs photosynthesis and reduces size, productivity, and quality in many of the crop plant species. Increased exposure of UV light reduces chlorophyll contents a, b and total content in plants. Titanium Dioxide (TiO 2 ) is a wide band gap semiconductor and efficient light harvester. TiO 2 has strong UltraViolet (UV) light absorbing capability. Here, we have studied the performance of TiO 2 thin films as a protective layer to the chlorophyll contents present in medicinal plant, tulsi (Ocimum tenuiflorum L) from UV radiation. The study reveals that crystallite size increases, transmittance decreases and chlorophyll contents increases with increase in annealing temperature. This study showed that TiO 2 thin films are good absorber of UV light and protect the chlorophyll contents a, b and total content in medicinal plants

Improved optical response and photocatalysis for N-doped titanium oxide (TiO2) films prepared by oxidation of TiN

International Nuclear Information System (INIS)

Wan, L.; Li, J.F.; Feng, J.Y.; Sun, W.; Mao, Z.Q.

2007-01-01

In order to improve the photocatalytic activity, N-doped titanium oxide (TiO 2 ) films were obtained by thermal oxidation of TiN films, which were prepared on Ti substrates by ion beam assisted deposition (IBAD). The dominating rutile TiO 2 phase was found in films after thermal oxidation. According to the results of X-ray photoelectron spectroscopy (XPS), the residual N atoms occupied O-atom sites in TiO 2 lattice to form Ti-O-N bonds. UV-vis spectra revealed the N-doped TiO 2 film had a red shift of absorption edge. The maximum red shift was assigned to the sample annealed at 750 deg. C, with an onset wavelength at 600 nm. The onset wavelength corresponded to the photon energy of 2.05 eV, which was nearly 1.0 eV below the band gap of pure rutile TiO 2 . The effect of nitrogen was responsible for the enhancement of photoactivity of N-doped TiO 2 films in the range of visible light

Contribution of thickness dependent void fraction and TiSixOy interlayer to the optical properties of amorphous TiO2 thin films

International Nuclear Information System (INIS)

Zhang, Fan; Zhang, Rong-Jun; Zheng, Yu-Xiang; Xu, Zi-Jie; Zhang, Dong-Xu; Wang, Zi-Yi; Yu, Xiang; Chen, Liang-Yao

2013-01-01

The optical properties of TiO 2 thin films prepared by electron beam evaporation were studied by spectroscopic ellipsometry and analyzed quantitatively using effective medium approximation theory and an effective series capacitance model. The refractive indices of TiO 2 are essentially constant and approach to those of bulk TiO 2 for films thicker than 40 nm, but drop sharply with a decrease in thickness from 40 to 5.5 nm. This phenomenon can be interpreted quantitatively by the thickness dependence of the void fraction and interfacial oxide region. The optical band gaps calculated from Tauc law increase with an increase of film thickness, and can be attributed to the contribution of disorder effect. - Highlights: • Amorphous TiO 2 thin films fabricated on Si substrate by electron beam evaporation • The refractive index and band gap are obtained from spectroscopic ellipsometry. • The refractive index decreases with decreasing film thickness. • Effective medium approximation theory and effective series capacitance model introduced • A band gap increases gradually with an increase in film thickness

Effect of N_2 flow rate on the properties of N doped TiO_2 films deposited by DC coupled RF magnetron sputtering

International Nuclear Information System (INIS)

Peng, Shou; Yang, Yong; Li, Gang; Jiang, Jiwen; Jin, Kewu; Yao, TingTing; Zhang, Kuanxiang; Cao, Xin; Wang, Yun; Xu, Genbao

2016-01-01

N doped TiO_2 films were deposited on glass substrates at room temperature using DC coupled RF magnetron sputtering with a TiO_2 ceramic target. The influences of N_2 flow rate on the deposition rate, crystal structure, chemical composition and band gap of the deposited films were investigated by Optical profiler, X-ray diffraction, X-ray photoelectron spectroscope and ultraviolet-visible spectrophotometer. The film growth rate gradually decreased with increasing N_2 flow rate. As N_2 flow rate increased, the crystallization of the films deteriorated, and the films tended to form amorphous structure. XPS analysis revealed that N dopant atoms were added at the substitutional sites into TiO_2 lattice structure. FE-SEM results showed that the grain size of the film decreased and the crystallinity degraded as N_2 flow rate increases. In addition, N doping caused an obvious red shift in the optical absorption edge. - Highlights: • N doped TiO_2 films were deposited by DC coupled RF magnetron reactive sputtering. • As N_2 flow rate increases, the crystallization of the deposited films degrades. • The higher N_2 flow rate is beneficial to form more substituted N in the film. • N doping causes an obvious red shift in the absorption wavelength.

Thin TiO2 films deposited by implantation and sputtering in RF inductively coupled plasmas

International Nuclear Information System (INIS)

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

2012-01-01

The achievement of titanium dioxide (TiO 2 ) thin films in the rutile crystalline phase is reported. The samples result from the implantation of oxygen ions of Ti in argon/oxygen plasma generated by inductively coupled RF at a commercial 13.56 MHz frequency. Simultaneously, a sputtering process is conducted on the titanium target in order to produce TiO 2 thin films in the anatase phase over silicon and glass substrates. Both implantation and sputtering processes shared the same 500 W plasma with the target, polarized between 0 and -3 kV. The substrates were placed between 2 and 3 cm from the target, this distance being found to be determinant of the TiO 2 deposition rate. The rutile phase in the target was obtained at temperatures in the order of 680 degrees C and the anatase (unbiased) one at about 300 degrees C without any auxiliary heating. The crystalline phases were characterized by x ray diffraction and Raman spectroscopy. The morphology and average roughness were established by means of scanning electronic and atomic force microscopy, whereas the reaction products generated during the oxidation process were analyzed by mass spectrometry. Finally, the stoichiometric composition was measured by means of X-ray photoelectron spectroscopy.

Fabrication and Film Qualification of Sr Modified Pb(Ca) TiO3 Thin Films

International Nuclear Information System (INIS)

Naw Hla Myat San; Khin Aye Thwe; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

2011-12-01

Strontium and calcium - modified lead titanate (Pb0.7 Ca0.15 Sr0.15 ) TiO3 (PCST)thin films were prepared by using spin coating technique. Phase transition of PCST was interpreted by means of Er-T characteristics. Process temperature dependence on micro-structure of PCST film was studied. Charge conduction mechanism of PCST thin film was also investigated for film qualification.

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

International Nuclear Information System (INIS)

Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

2010-01-01

Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

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)

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

2011-01-01

Titanium dioxide (TiO 2 ) thin films doping of various iron ion (Fe 3+ ) concentrations were deposited on silicon (Si) (100) and quartz substrates by sol-gel Spin Coating technique followed by a thermal treatment at 600 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 TiO 2 thin films comprised only the anatase TiO 2 , but the crystallinity decreased when the Fe 3+ content increased from 0% to 20%. During the Fe 3+ addition to 20%, the phase of TiO 2 thin film still maintained the amorphous state. The grain size calculated from XRD patterns varies from 29.3 to 22.6 nm. The complex index and the optical band gap (E g ) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreased with an increasing Fe 3+ content.

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.

Effect of precursor concentration and film thickness deposited by layer on nanostructured TiO2 thin films

Science.gov (United States)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Sol-gel spin coating method is used in the production of nanostructured TiO2 thin film. The surface topology and morphology was observed using the Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The electrical properties were investigated by using two probe current-voltage (I-V) measurements to study the electrical resistivity behavior, hence the conductivity of the thin film. The solution concentration will be varied from 14.0 to 0.01wt% with 0.02wt% interval where the last concentration of 0.02 to 0.01wt% have 0.01wt% interval to find which concentrations have the highest conductivity then the optimized concentration's sample were chosen for the thickness parameter based on layer by layer deposition from 1 to 6 layer. Based on the result, the lowest concentration of TiO2, the surface becomes more uniform and the conductivity will increase. As the result, sample of 0.01wt% concentration have conductivity value of 1.77E-10 S/m and will be advanced in thickness parameter. Whereas in thickness parameter, the 3layer deposition were chosen as its conductivity is the highest at 3.9098E9 S/m.

Influence of annealing on X-ray radiation sensing properties of TiO2 thin film

Science.gov (United States)

Sarma, M. P.; Kalita, J. M.; Wary, G.

2018-03-01

A recent study shows that the titanium dioxide (TiO2) thin film synthesised by a chemical bath deposition technique is a very useful material for the X-ray radiation sensor. In this work, we reported the influence of annealing on the X-ray radiation detection sensitivity of the TiO2 film. The films were annealed at 333 K, 363 K, 393 K, 473 K, and 573 K for 1 hour. Structural analyses showed that the microstrain and dislocation density decreased whereas the average crystallite size increased with annealing. The band gap of the films also decreased from 3.26 eV to 3.10 eV after annealing. The I-V characteristics record under the dark condition and under the X-ray irradiation showed that the conductivity increased with annealing. The influence of annealing on the detection sensitivity was negligible if the bias voltage applied across the films was low (within 0.2 V‒1.0 V). At higher bias voltage (>1.0 V), the contribution of electrons excited by X-ray became less significant which affected the detection sensitivity.

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

International Nuclear Information System (INIS)

Tachikawa, Takashi

2012-01-01

We demonstrate control of the carrier density of single phase anatase TiO 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 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.

Hydrogen incorporation by plasma treatment gives mesoporous black TiO ₂ thin films with visible photoelectrochemical water oxidation activity

Energy Technology Data Exchange (ETDEWEB)

Islam, Syed Z.; Reed, Allen; Nagpure, Suraj; Wanninayake, Namal; Browning, James F.; Strzalka, Joseph; Kim, Doo Young; Rankin, Stephen E.

2018-05-01

In this work, we use neutron reflectometry (NR) to investigate the roles of hydrogen in plasma treated hydrogen doped mesoporous black titania thin films in their visible light absorption and enhanced photoactivity for water oxidation. The cubic ordered mesoporous TiO2 thin films are prepared by a surfactant-templated sol-gel method and are treated with hydrogen plasma, an approach hypothesized to capitalize on the high degree of disorder in the material and the high energy of the plasma species to achieve efficient hydrogen doping. UV-vis absorbance spectra indicate that H2 plasma treatment makes TiO2 films black, with broad-spectrum enhancement of visible light absorption, and XPS analysis shows peak for Ti3+ state in treated films. The presence of hydrogen in black mesoporous titania (H-TiO2) films is confirmed by the scattering length density (SLD) profiles obtained from neutron reflectometry measurements. The H-TiO2 shows ca. 28 times and 8 times higher photocurrent for photoelectrochemical water oxidation compared to undoped TiO2 films under UV (365 nm) and blue (455 nm) LED irradiation, respectively. These findings provide the first direct evidence that the dramatic change in visible light absorbance of H-treated black TiO2 is accompanied by significant hydrogen uptake and not just Ti3+ generation or surface disordering.

Enhanced Optical and Electrical Properties of TiO_2 Buffered IGZO/TiO_2 Bi-Layered Films

International Nuclear Information System (INIS)

Moon, Hyun-Joo; Kim, Daeil

2016-01-01

In and Ga doped ZnO (IGZO, 100-nm thick) thin films were deposited by radio frequency magnetron sputtering without intentional substrate heating on a bare glass substrate and a TiO_2-deposited glass substrate to determine the effect of the thickness of a thin TiO_2 buffer layer on the structural, optical, and electrical properties of the films. The thicknesses of the TiO_2 buffer layers were 5, 10 and 15 nm, respectively. As-deposited IGZO films with a 10 nm-thick TiO_2 buffer layer had an average optical transmittance of 85.0% with lower resistivity (1.83×10-2 Ω cm) than that of IGZO single layer films. The figure of merit (FOM) reached a maximum of 1.44×10-4 Ω-1 for IGZO/10 nm-thick TiO_2 bi-layered films, which is higher than the FOM of 6.85×10-5 Ω-1 for IGZO single layer films. Because a higher FOM value indicates better quality transparent conducting oxide (TCO) films, the IGZO/10 nm-thick TiO_2 bi-layered films are likely to perform better in TCO applications than IGZO single layer films.

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

Directory of Open Access Journals (Sweden)

Bernardi M. I. B.

2002-01-01

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.

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

International Nuclear Information System (INIS)

Cimpean, Anisoara; Popescu, Simona; Ciofrangeanu, Cristina M.; Gleizes, Alain N.

2011-01-01

We report on the in vitro response of human gingival fibroblasts (HGF-1 cell line) to various thin films of titanium dioxide (TiO 2 ) 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 TiO 2 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 TiO 2 proved effective in positively modifying titanium surface for medical applications. Surface properties playing a crucial role for cell behavior were the wettability and, secondarily, the roughness, HGF-1 cells preferring a moderately rough and wettable TiO 2 coating.

Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

International Nuclear Information System (INIS)

Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

2012-01-01

Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO 2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH 4 F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O 2− ions by N 3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO 1.83 N 0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

Combination of short-length TiO_2 nanorod arrays and compact PbS quantum-dot thin films for efficient solid-state quantum-dot-sensitized solar cells

International Nuclear Information System (INIS)

Zhang, Zhengguo; Shi, Chengwu; Chen, Junjun; Xiao, Guannan; Li, Long

2017-01-01

Graphical abstract: The TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, the areal density of 500 μm"−"2 was successfully prepared. The compact PbS quantum-dot thin film was firstly obtained on the TiO_2 nanorod array by spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol. The photoelectric conversion efficiency (PCE) of the compact PbS quantum-dot thin film sensitized solar cells achieved 4.10% using spiro-OMeTAD as a hole transporting layer, while the PCE of the PbS quantum-dot sensitized solar cells was only 0.54%. - Highlights: • Preparation of TiO_2 nanorod arrays with the length of 600 nm, diameter of 20 nm. • The compact PbS QD thin film and short-length TiO_2 nanorod array were combined. • EDT addition improved PbS nanoparticle coverage and photovoltaic performance. • The compact PbS QD thin film sensitized solar cell achieved the PCE of 4.10%. - Abstract: Considering the balance of the hole diffusion length and the loading quantity of quantum-dots, the rutile TiO_2 nanorod array with the length of 600 nm, the diameter of 20 nm, and the areal density of 500 μm"−"2 is successfully prepared by the hydrothermal method using the aqueous grown solution of 38 mM titanium isopropoxide and 6 M hydrochloric acid at 170 °C for 105 min. The compact PbS quantum-dot thin film on the TiO_2 nanorod array is firstly obtained by the spin-coating-assisted successive ionic layer absorption and reaction with using 1,2-ethanedithiol (EDT). The result reveals that the strong interaction between lead and EDT is very important to control the crystallite size of PbS quantum-dots and obtain the compact PbS quantum-dot thin film on the TiO_2 nanorod array. The all solid-state sensitized solar cell with the combination of the short-length, high-density TiO_2 nanorod array and the compact PbS quantum-dot thin film achieves the photoelectric conversion efficiency of 4.10%, along with an open

Damage performance of TiO2/SiO2 thin film components induced by a long-pulsed laser

International Nuclear Information System (INIS)

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

2011-01-01

In order to study the long-pulsed laser induced damage performance of optical thin films, damage experiments of TiO 2 /SiO 2 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.

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

International Nuclear Information System (INIS)

Cueto, Luisa F.; Sanchez, Enrique; Torres-Martinez, Leticia M.; Hirata, Gustavo A.

2005-01-01

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

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

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2007-01-01

We report on visible-light sensitivity in N-doped TiO 2 (TiO 2 :N) films that were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined by X-ray photoelectron spectroscopy measurements. From transmission electron microscopic observations and optical absorption measurements, yellow-colored TiO 2 :N samples showed an enhanced granular structure and strong absorption in the visible-light region. Photoelectron spectroscopy in air measurements showed a noticeable decrease in ionization energy of TiO 2 by the N doping. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. The pronounced 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing of TiO 2 by mixing with the O 2p valence band. Therefore, this localized intraband is probably one origin of visible-light sensitivity in TiO 2 :N

Study the target effect on the structural, surface and optical properties of TiO2 thin film fabricated by RF sputtering method

Science.gov (United States)

Vyas, Sumit; Tiwary, Rohit; Shubham, Kumar; Chakrabarti, P.

2015-04-01

The effect of target (Ti metal target and TiO2 target) on Titanium Dioxide (TiO2) thin films grown on ITO coated glass substrate by RF magnetron sputtering has been investigated. A comparative study of both the films was done in respect of crystalline structure, surface morphology and optical properties by using X-ray diffractometer (XRD), Atomic Force Microscopy (AFM) studies and ellipsometric measurements. The XRD results confirmed the crystalline structure and indicated that the deposited films have the intensities of anatase phase. The surface morphology and roughness values indicated that the film using Ti metal target has a smoother surface and densely packed with grains as compared to films obtained using TiO2 target. A high transmission in the visible region, and direct band gap of 3.67 eV and 3.75 eV for films derived by using Ti metal and TiO2 target respectively and indirect bandgap of 3.39 eV for the films derived from both the targets (Ti metal and TiO2 target) were observed by the ellipsometric measurements.

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.

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

International Nuclear Information System (INIS)

Arpac, E.; Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, Nadir; Sayilkan, H.

2007-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO 2 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-TiO 2 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 TiO 2 thin film

Fabrication of assembled ZnO/TiO2 heterojunction thin film transistors using solution processing technique

Science.gov (United States)

Liau, Leo Chau-Kuang; Lin, Yun-Guo

2015-01-01

Ceramic-based metal-oxide-semiconductor (MOS) field-effect thin film transistors (TFTs), which were assembled by ZnO and TiO2 heterojunction films coated using solution processing technique, were fabricated and characterized. The fabrication of the device began with the preparation of ZnO and TiO2 films by spin coating. The ZnO and TiO2 films that were stacked together and annealed at 450 °C were characterized as a p-n junction diode. Two types of the devices, p-channel and n-channel TFTs, were produced using different assemblies of ZnO and TiO2 films. Results show that the p-channel TFTs (p-TFTs) and n-channel TFTs (n-TFTs) using the assemblies of ZnO and TiO2 films were demonstrated by source-drain current vs. drain voltage (IDS-VDS) measurements. Several electronic properties of the p- and n- TFTs, such as threshold voltage (Vth), on-off ratio, channel mobility, and subthreshold swing (SS), were determined by current-voltage (I-V) data analysis. The ZnO/TiO2-based TFTs can be produced using solution processing technique and an assembly approach.

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

International Nuclear Information System (INIS)

Hsu, Cheng-Hsing; Tseng, Ching-Fang; Lai, Chun-Hung; Tung, Hsin-Han; Lin, Shih-Yao

2010-01-01

In this paper, we investigated electrical properties and microstructures of ZrTiO 4 (ZrO 2 -TiO 2 ) thin films prepared by the sol-gel method on ITO substrates at different annealing temperatures. All films exhibited ZrTiO 4 (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/cm 2 was obtained for the prepared films. Considering the primary memory switching behavior of ZrTiO 4 , ReRAM based on ZrTiO 4 shows promise for future nonvolatile memory applications.

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

International Nuclear Information System (INIS)

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

2014-01-01

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO 2 –Cu 2 O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO 2 , the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. (papers)

Incorporation of Kojic Acid-Azo Dyes on TiO2 Thin Films for Dye Sensitized Solar Cells Applications

Directory of Open Access Journals (Sweden)

Carolynne Zie Wei Sie

2017-01-01

Full Text Available Sensitization of heavy metal free organic dyes onto TiO2 thin films has gained much attention in dye sensitized solar cells (DSSCs. A series of new kojic acid based organic dyes KA1–4 were synthesized via nucleophilic substitution of azobenzene bearing different vinyl chains A1–4 with kojyl chloride 4. Azo dyes KA1–4 were characterized for photophysical properties employing absorption spectrometry and photovoltaic characteristic in TiO2 thin film. The presence of vinyl chain in A1–4 improved the photovoltaic performance from 0.20 to 0.60%. The introduction of kojic acid obtained from sago waste further increases the efficiency to 0.82–1.54%. Based on photovoltaic performance, KA4 achieved the highest solar to electrical energy conversion efficiency (η = 1.54% in the series.

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

International Nuclear Information System (INIS)

Ali, Riyaz Ahmad Mohamed; Nayan, Nafarizal

2013-01-01

Lately, titanium dioxide (TiO 2 ) films with anatase crystalline property received numerous attentions as unique material properties. There are wide applications of TiO 2 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 (O 2 ) 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 2θ = 25.28°, plane (202) at 2θ = 48.05° and plane (211) at 2θ = 55.06°. In addition, it is our interest to study the plasma properties and optical spectrum of Ti, Ti+ , O- , ArM and Ar+ in the chamber during the deposition process. Result of emission line intensities, electron density and temperature from optical spectroscope and Langmuir probe will be discuss further during the workshop. This works were supported by Graduate Incentive Scheme of Universiti Tun Hussein Onn Malaysia (UTHM) and Fundamental Research Grant Scheme of Ministry of Higher Education, Malaysia. (author)

Seebeck coefficient of synthesized Titanium Dioxide thin film on FTO glass substrate

Science.gov (United States)

Usop, R.; Hamed, N. K. A.; Megat Hasnan, M. M. I.; Ikeda, H.; Sabri, M. F. M.; Ahmad, M. K.; Said, S. M.; Salleh, F.

2018-04-01

In order to fabricate a thermoelectric device on glass substrate for harvesting waste heat energy through house appliances, the Seebeck coefficient of translucent TiO2 thin film was investigated. The TiO2 thin film was synthesized by using hydrothermal method with F-SnO2 coated glass as substrate. From scanning electron microscopy analysis, the synthesized TiO2 thin film was found to be in nanometer-scale rod structure with a thickness of 4 µm. The Seebeck coefficient was measured in the temperature range of 300 – 400 K. The Seebeck coefficient is found to be in negative value which shows that synthesized film is an n-type semiconductor material, and is lower than the value of bulk-size material. This reduction in Seebeck coefficient of TiO2 thin film is likely due to the low dimensional effect and the difference of carrier concentration.

Pt Catalyst Supported within TiO2 Mesoporous Films for Oxygen Reduction Reaction

International Nuclear Information System (INIS)

Huang, Dekang; Zhang, Bingyan; Bai, Jie; Zhang, Yibo; Wittstock, Gunther; Wang, Mingkui; Shen, Yan

2014-01-01

In this study, dispersed Pt nanoparticles into mesoporous TiO 2 thin films are fabricated by a facile electrochemical deposition method as electro-catalysts for oxygen reduction reaction. The mesoporous TiO 2 thin films coated on the fluorine-doped tin oxide glass by screen printing allow a facile transport of reactants and products. The structural properties of the resulted Pt/TiO 2 electrode are evaluated by field emission scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Cyclic voltammetry measurements are performed to study the electrochemical properties of the Pt/TiO 2 electrode. Further study demonstrates the stability of the Pt catalyst supported within TiO 2 mesoporous films for the oxygen reduction reaction

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 μm × 350 μm 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.

Strong out-of-plane magnetic anisotropy in ion irradiated anatase TiO2 thin films

Directory of Open Access Journals (Sweden)

M. Stiller

2016-12-01

Full Text Available The temperature and field dependence of the magnetization of epitaxial, undoped anatase TiO2 thin films on SrTiO3 substrates was investigated. Low-energy ion irradiation was used to modify the surface of the films within a few nanometers, yet with high enough energy to produce oxygen and titanium vacancies. The as-prepared thin film shows ferromagnetism which increases after irradiation with low-energy ions. An optimal and clear magnetic anisotropy was observed after the first irradiation, opposite to the expected form anisotropy. Taking into account the experimental parameters, titanium vacancies as di-Frenkel pairs appear to be responsible for the enhanced ferromagnetism and the strong anisotropy observed in our films. The magnetic impurities concentrations was measured by particle-induced X-ray emission with ppm resolution. They are ruled out as a source of the observed ferromagnetism before and after irradiation.

Manufacturing and investigation of surface morphology and optical properties of composite thin films reinforced by TiO2, Bi2O3 and SiO2 nanoparticles

Science.gov (United States)

Jarka, Paweł; Tański, Tomasz; Matysiak, Wiktor; Krzemiński, Łukasz; Hajduk, Barbara; Bilewicz, Marcin

2017-12-01

The aim of submitted paper is to present influence of manufacturing parameters on optical properties and surface morphology of composite materials with a polymer matrix reinforced by TiO2 and SiO2 and Bi2O3 nanoparticles. The novelty proposed by the authors is the use of TiO2 and SiO2 and Bi2O3 nanoparticles simultaneously in polymeric matrix. This allows using the combined effect of nanoparticles to a result composite material. The thin films of composite material were prepared by using spin-coating method with various spinning rates from solutions of different concentration of nanoparticles. In order to prepare the spinning solution polymer, Poly(methyl methacrylate) (PMMA) was used as a matrix. The reinforcing phase was the mixture of the nanoparticles of SiO2, TiO2 and B2O3. In order to identify the surface morphology of using thin films and arrangement of the reinforcing phase Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) were used. In order to study the optical properties of the obtained thin films, the thin films of composites was subjected to an ellipsometry analysis. The measurements of absorbance of the obtained materials, from which the value of the band gap width was specified, were carried out using the UV/VIS spectroscopy. The optical properties of obtain composite thin films depend not only on the individual components used, but also on the morphology and the interfacial characteristics. Controlling the participation of three kinds of nanoparticles of different sizes and optical parameters allows to obtaining the most optimal optical properties of nanocomposites and also controlling the deposition parameters allows to obtaining the most optimal surface morphology of nanocomposites.

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

International Nuclear Information System (INIS)

Lewis, S.; Haynes, V.; Wheeler-Jones, R.; Sly, J.; Perks, R.M.; Piccirillo, L.

2010-01-01

Poly(methylmethacrylate) (PMMA) based nanocomposite electron beam resists have been demonstrated by spin coating techniques. When TiO 2 and Al 2 O 3 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 TiO 2 and Al 2 O 3 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 TiO 2 and Al 2 O 3 were suspended in methanol before being dispersed into the PMMA polymer.

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

International Nuclear Information System (INIS)

Yokota, Katsuhiro; Yano, Yoshinori; Miyashita, Fumiyoshi

2006-01-01

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 εo 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

Aerosol deposition of Ba0.8Sr0.2TiO3 thin films

Directory of Open Access Journals (Sweden)

Branković Zorica

2009-01-01

Full Text Available In this work we optimized conditions for aerosol deposition of homogeneous, nanograined, smooth Ba0.8Sr0.2TiO3 thin films. Investigation involved optimization of deposition parameters, namely deposition time and temperature for different substrates. Solutions were prepared from titanium isopropoxide, strontium acetate and barium acetate. Films were deposited on Si (1 0 0 or Si covered by platinum (Pt (1 1 1 /Ti/SiO2/Si. Investigation showed that the best films were obtained at substrate temperature of 85ºC. After deposition films were slowly heated up to 650ºC, annealed for 30 min, and slowly cooled. Grain size of BST films deposited on Si substrate were in the range 40-70 nm, depending on deposition conditions, while the same films deposited on Pt substrates showed mean grain size in the range 35-50 nm. Films deposited under optimal conditions were very homogeneous, crackfree, and smooth with rms roughness lower than 4 nm for both substrates.

Effect of substrate type on the electrical and structural properties of TiO2 thin films deposited by reactive DC sputtering

Science.gov (United States)

Cheng, Xuemei; Gotoh, Kazuhiro; Nakagawa, Yoshihiko; Usami, Noritaka

2018-06-01

Electrical and structural properties of TiO2 thin films deposited at room temperature by reactive DC sputtering have been investigated on three different substrates: high resistivity (>1000 Ω cm) float zone Si(1 1 1), float zone Si(1 0 0) and alkali free glass. As-deposited TiO2 films on glass substrate showed extremely high resistivity of (∼5.5 × 103 Ω cm). In contrast, lower resistivities of ∼2 Ω cm and ∼5 Ω cm were obtained for films on Si(1 1 1) and Si(1 0 0), respectively. The as-deposited films were found to be oxygen-rich amorphous TiO2 for all the substrates as evidenced by X-ray photoemission spectroscopy and X-ray diffraction. Subsequent annealing led to appearance of anatase TiO2 on Si but not on glass. The surface of as-deposited TiO2 on Si was found to be rougher than that on glass. These results suggest that the big difference of electrical resistivity of TiO2 would be related with existence of more anatase nuclei forming on crystalline substrates, which is consistent with the theory of charged clusters that smaller clusters tend to adopt the substrate structure.

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

International Nuclear Information System (INIS)

Kyeremateng, Nana Amponsah; Hornebecq, Virginie; Knauth, Philippe; Djenizian, Thierry

2012-01-01

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

Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

Science.gov (United States)

Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

2018-02-01

Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

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)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

2008-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO 2 based thin films, contain at different solid ratio of TiO 2 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-TiO 2 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 TiO 2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

Directory of Open Access Journals (Sweden)

Damon Rafieian

2015-09-01

Full Text Available We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2, obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

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

International Nuclear Information System (INIS)

Foster, C.M.; Chiarello, R.P.; Chang, H.L.M.; You, H.; Zhang, T.J.; Frase, H.; Parker, J.C.; Lam, D.J.

1993-01-01

Epitaxial thin films of TiO 2 and VO 2 single layers and TiO 2 /VO 2 multilayers were grown on (11 bar 20) sapphire (α-Al 2 O 3 ) substrates using the metalorganic chemical vapor deposition technique and were characterized using Raman scattering and four x-ray diffractometry. X-ray diffraction results indicate that the films are high quality single crystal material with well defined growth plane and small in-plane and out-of-plane mosaic. Single-layer films are shown to obey the Raman selection rules of TiO 2 and VO 2 single crystals. The close adherence to the Raman selection rules indicates the high degree of orientation of the films, both parallel and perpendicular to the growth plane. Selection rule spectra of two and three layer TiO 2 /VO 2 multilayers are dominated by the VO 2 layers with only minimal signature of the TiO 2 layers. Due to the low band gap of semiconducting vanadium dioxide, we attribute the strong signature of the VO 2 layers to resonant enhancement of the VO 2 Raman component accompanied with absorption of the both the incident and scattered laser light from the TiO 2 layers

Photocatalytic Anatase TiO2 Thin Films on Polymer Optical Fiber Using Atmospheric-Pressure Plasma.

Science.gov (United States)

Baba, Kamal; Bulou, Simon; Choquet, Patrick; Boscher, Nicolas D

2017-04-19

Due to the undeniable industrial advantages of low-temperature atmospheric-pressure plasma processes, such as low cost, low temperature, easy implementation, and in-line process capabilities, they have become the most promising next-generation candidate system for replacing thermal chemical vapor deposition or wet chemical processes for the deposition of functional coatings. In the work detailed in this article, photocatalytic anatase TiO 2 thin films were deposited at a low temperature on polymer optical fibers using an atmospheric-pressure plasma process. This method overcomes the challenge of forming crystalline transition metal oxide coatings on polymer substrates by using a dry and up-scalable method. The careful selection of the plasma source and the titanium precursor, i.e., titanium ethoxide with a short alkoxy group, allowed the deposition of well-adherent, dense, and crystalline TiO 2 coatings at low substrate temperature. Raman and XRD investigations showed that the addition of oxygen to the precursor's carrier gas resulted in a further increase of the film's crystallinity. Furthermore, the films deposited in the presence of oxygen exhibited a better photocatalytic activity toward methylene blue degradation assumedly due to their higher amount of photoactive {101} facets.

Defect controlled tuning of the ratio of ultraviolet to visible light emission in TiO2 thin films

International Nuclear Information System (INIS)

Mondal, S.; Basak, D.

2016-01-01

The photoluminescence (PL) of sol–gel TiO 2 thin film has been found to be largely dependent on the post-deposition processing such as annealing at 500 °C in air, vacuum and ultraviolet (UV) light curing at room temperature. A detailed analysis of room temperature PL spectra shows that the UV/VIS PL peak intensity ratio is maximum for the film which has been annealed at 500 °C in air. X-ray photoelectron spectroscopy confirms the presence of Ti 3+ type of point defects. The visible emission is deconvoluted to green and orange emissions. Analyses of the present experimental results indicate that V O and/or Ti 3+ causes the green emission and OH and/or excess O 2 adsorption on TiO 2 surface probably causes the orange emission. The time correlated single photon counting spectroscopy data of the UV PL indicates higher number defects in vacuum annealed and UV cured films as compared to the air annealed film. Correlation of the results altogether allows us to conclude that the surface defects those causing the visible emission are smaller in number in the air annealed film. The present results may be useful for tuning the relative PL intensities of UV, green and orange emissions. - Highlights: • Sol–gel TiO 2 films were treated both in air, vacuum at 500 °C and under UV light (room temperature). • UV/VIS PL intensity ratio is maximum for air annealed and minimum for UV cured films. • Both green and orange emission predominantly controls the visible emission of TiO 2 . • The visible emission exhibit a clear correlation with Ti 3+  defects on the surface.

Ambiguous Role of Growth-Induced Defects on the Semiconductor-to-Metal Characteristics in Epitaxial VO2/TiO2 Thin Films.

Science.gov (United States)

Mihailescu, Cristian N; Symeou, Elli; Svoukis, Efthymios; Negrea, Raluca F; Ghica, Corneliu; Teodorescu, Valentin; Tanase, Liviu C; Negrila, Catalin; Giapintzakis, John

2018-04-25

Controlling the semiconductor-to-metal transition temperature in epitaxial VO 2 thin films remains an unresolved question both at the fundamental as well as the application level. Within the scope of this work, the effects of growth temperature on the structure, chemical composition, interface coherency and electrical characteristics of rutile VO 2 epitaxial thin films grown on TiO 2 substrates are investigated. It is hereby deduced that the transition temperature is lower than the bulk value of 340 K. However, it is found to approach this value as a function of increased growth temperature even though it is accompanied by a contraction along the V 4+ -V 4+ bond direction, the crystallographic c-axis lattice parameter. Additionally, it is demonstrated that films grown at low substrate temperatures exhibit a relaxed state and a strongly reduced transition temperature. It is suggested that, besides thermal and epitaxial strain, growth-induced defects may strongly affect the electronic phase transition. The results of this work reveal the difficulty in extracting the intrinsic material response to strain, when the exact contribution of all strain sources cannot be effectively determined. The findings also bear implications on the limitations in obtaining the recently predicted novel semi-Dirac point phase in VO 2 /TiO 2 multilayer structures.

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

Science.gov (United States)

Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-01

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

Role of oxygen vacancies in anodic TiO2 thin films

International Nuclear Information System (INIS)

Tit, N.; Halley, J.W.

1992-05-01

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 TiO 2 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 p c =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

Heterogeneous photocatalytic degradation of toluene in static environment employing thin films of nitrogen-doped nano-titanium dioxide

Science.gov (United States)

Kannangara, Yasun Y.; Wijesena, Ruchira; Rajapakse, R. M. G.; de Silva, K. M. Nalin

2018-04-01

Photocatalytic semiconductor thin films have the ability to degrade volatile organic compounds (VOCs) causing numerous health problems. The group of VOCs called "BTEX" is abundant in houses and indoor of automobiles. Anatase phase of TiO2 has a band gap of 3.2 eV and UV radiation is required for photogeneration of electrons and holes in TiO2 particles. This band gap can be decreased significantly when TiO2 is doped with nitrogen (N-TiO2). Dopants like Pd, Cd, and Ag are hazardous to human health but N-doped TiO2 can be used in indoor pollutant remediation. In this research, N-doped TiO2 nano-powder was prepared and characterized using various analytical techniques. N-TiO2 was made in sol-gel method and triethylamine (N(CH2CH3)3) was used as the N-precursor. Modified quartz cell was used to measure the photocatalytic degradation of toluene. N-doped TiO2 nano-powder was illuminated with visible light (xenon lamp 200 W, λ = 330-800 nm, intensity = 1 Sun) to cause the degradation of VOCs present in static air. Photocatalyst was coated on a thin glass plate, using the doctor-blade method, was inserted into a quartz cell containing 2.00 µL of toluene and 35 min was allowed for evaporation/condensation equilibrium and then illuminated for 2 h. Remarkably, the highest value of efficiency 85% was observed in the 1 μm thick N-TiO2 thin film. The kinetics of photocatalytic degradation of toluene by N-TiO2 and P25-TiO2 has been compared. Surface topology was studied by varying the thickness of the N-TiO2 thin films. The surface nanostructures were analysed and studied with atomic force microscopy with various thin film thicknesses.

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)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

2007-01-01

Nanostructure Sn 4+ -doped TiO 2 based mono and double layer thin films, contain 50% solid ratio of TiO 2 in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn 4+ -doped nano-TiO 2 particle a doping ratio of about 5[Sn 4+ /Ti(OBu n ) 4 ; mol/mol%] has been synthesized by hydrotermal process at 225 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-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

Formation of thin film like assembly of exfoliated C3N4 nanoflakes by solvent non-evaporative method using centrifuge

Science.gov (United States)

Tejasvi, Ravi; Basu, Suddhasatwa

2017-12-01

A simple method for depositing a thin film of nanomaterial on a substrate using centrifugation technique has been developed, whereby solvent evaporation is prevented and solvent reuse is possible. The centrifuge technique of deposition yields uniform, smooth thin film irrespective of substrate surface texture. The deposited TiO2/eC3N4 film studied, through field emission scanning electron microscope, atomic force microscope, and optical surface profilometer, shows variation in surface roughness on the basis of centrifugation speeds. Initially film coverage improves and surface roughness decreases with the increase in rpm of the centrifuge and the surface roughness slightly increases with further increase in rpm. The photoelectrochemical studies of TiO2/eC3N4 films suggest that the centrifuge technique forms better heterojunctions compared to that by spin coating technique leading to enhanced photoelectrochemical water splitting.

Effects of reductive annealing on insulating polycrystalline thin films of Nb-doped anatase TiO2: recovery of high conductivity

International Nuclear Information System (INIS)

Nakao, Shoichiro; Hirose, Yasushi; Hasegawa, Tetsuya

2016-01-01

We studied the effects of reductive annealing on insulating polycrystalline thin films of anatase Nb-doped TiO 2 (TNO). The insulating TNO films were intentionally fabricated by annealing conductive TNO films in oxygen ambient at 400 °C. Reduced free carrier absorption in the insulating TNO films indicated carrier compensation due to excess oxygen. With H 2 -annealing, both carrier density and Hall mobility recovered to the level of conducting TNO, demonstrating that the excess oxygen can be efficiently removed by the annealing process without introducing additional scattering centers. (paper)

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

International Nuclear Information System (INIS)

Suda, Yoshiaki; Kawasaki, Hiroharu; Ohshima, Tamiko; Nakashima, Shouta; Kawazoe, Syuichi; Toma, Tetsuya

2006-01-01

Hydroxyapatite (HAp) coated on titanium dioxide (TiO 2 ) thin films has been developed to supplement the defects of both TiO 2 and HAp. Thin films have been prepared by pulsed laser deposition (PLD) method using HAp and HAp(10%) + TiO 2 targets. X-ray diffraction (XRD) shows that there are many small peaks of Ca 1 0(PO 4 ) 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 TiO 2 thin films have been prepared using HAp(10%) + TiO 2 targets. XRD and XPS measurements suggest that crystalline HAp + TiO 2 thin films are obtained by the PLD method using HAp(10%) + TiO 2 target

Nitrogen and europium doped TiO2 anodized films with applications in photocatalysis

International Nuclear Information System (INIS)

Chi, Choong-Soo; Choi, Jinwook; Jeong, Yongsoo; Lee, Oh Yeon; Oh, Han-Jun

2011-01-01

Micro-arc oxidation method is a useful process for mesoporous titanium dioxide films. In order to improve the photocatalytic activity of the TiO 2 film, N-Eu co-doped titania catalyst was synthesized by micro-arc oxidation in the H 2 SO 4 /Eu(NO 3 ) 3 mixture solution. The specific surface area and the roughness of the anodic titania film fabricated in the H 2 SO 4 /Eu(NO 3 ) 3 electrolyte, were increased compared to that of the anodic TiO 2 film prepared in H 2 SO 4 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 TiO 2 film significantly enhanced the photocatalytic activity for dye degradation. After dye decomposition test for 3 h, dye removal rates for the anodic TiO 2 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 TiO 2 band gap by N and Eu co-doping.

Suppressing the Photocatalytic Activity of TiO2 Nanoparticles by Extremely Thin Al2O3 Films Grown by Gas-Phase Deposition at Ambient Conditions

Directory of Open Access Journals (Sweden)

Jing Guo

2018-01-01

Full Text Available This work investigated the suppression of photocatalytic activity of titanium dioxide (TiO2 pigment powders by extremely thin aluminum oxide (Al2O3 films deposited via an atomic-layer-deposition-type process using trimethylaluminum (TMA and H2O as precursors. The deposition was performed on multiple grams of TiO2 powder at room temperature and atmospheric pressure in a fluidized bed reactor, resulting in the growth of uniform and conformal Al2O3 films with thickness control at sub-nanometer level. The as-deposited Al2O3 films exhibited excellent photocatalytic suppression ability. Accordingly, an Al2O3 layer with a thickness of 1 nm could efficiently suppress the photocatalytic activities of rutile, anatase, and P25 TiO2 nanoparticles without affecting their bulk optical properties. In addition, the influence of high-temperature annealing on the properties of the Al2O3 layers was investigated, revealing the possibility of achieving porous Al2O3 layers. Our approach demonstrated a fast, efficient, and simple route to coating Al2O3 films on TiO2 pigment powders at the multigram scale, and showed great potential for large-scale production development.

Structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics for a-IGZO thin-film transistors.

Science.gov (United States)

Chen, Fa-Hsyang; Her, Jim-Long; Shao, Yu-Hsuan; Matsuda, Yasuhiro H; Pan, Tung-Ming

2013-01-08

In this letter, we investigated the structural and electrical characteristics of high-κ Er2O3 and Er2TiO5 gate dielectrics on the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) devices. Compared with the Er2O3 dielectric, the a-IGZO TFT device incorporating an Er2TiO5 gate dielectric exhibited a low threshold voltage of 0.39 V, a high field-effect mobility of 8.8 cm2/Vs, a small subthreshold swing of 143 mV/decade, and a high Ion/Ioff current ratio of 4.23 × 107, presumably because of the reduction in the oxygen vacancies and the formation of the smooth surface roughness as a result of the incorporation of Ti into the Er2TiO5 film. Furthermore, the reliability of voltage stress can be improved using an Er2TiO5 gate dielectric.

Design and fabrication of ZnO/TiO2-based thin-film inverter circuits using solution processing techniques

International Nuclear Information System (INIS)

Liau, Leo Chau-Kuang; Kuo, Juo-Wei; Chiang, Hsin-Ni

2012-01-01

Novel and cost-effective ceramic-based thin-film inverter circuits, based on two layers of TiO 2 and ZnO films to construct junction field-effect transistors (FETs), were designed and fabricated by solution coating techniques. The double layers of the sol–gel ZnO and TiO 2 films were coated and characterized as a diode according to the current–voltage performance. Two types of FETs, the p-channel (p-FET) and the n-channel (n-FET) devices, were produced using different coating sequences of ZnO and TiO 2 layers. Both of the transistor performances were evaluated by analyzing the source–drain current versus voltage (I ds –V ds ) data with the control of the gate voltage (V g ). The ZnO/TiO 2 -based inverter circuits, such as the complementary-FET device, were further fabricated using the integration of the p-FET and the n-FET. The voltage transfer characteristics of the inverters were estimated by the tests of the input voltage (V in ) versus the output voltage (V out ) for the thin-film inverter circuits. (paper)

Studies on transient characteristics of unipolar resistive switching processes in TiO2 thin film grown by atomic layer deposition

Science.gov (United States)

Sahu, Vikas Kumar; Das, Amit K.; Ajimsha, R. S.; Misra, P.

2018-05-01

The transient characteristics of resistive switching processes have been investigated in TiO2 thin films grown by atomic layer deposition (ALD) to study the temporal evolution of the switching processes and measure the switching times. The reset and set switching times of unipolar Au/TiO2/Pt devices were found to be ~250 µs and 180 ns, respectively in the voltage windows of 0.5–0.9 V for reset and 1.9–4.8 V for set switching processes, obtained from quasi-static measurements. The reset switching time decreased exponentially with increasing amplitude of applied reset voltage pulse, while the set switching time remained insensitive to the amplitude of the set voltage pulse. A fast reset process with a switching time of ~400 ns was achieved by applying a reset voltage of ~1.8 V, higher than that of the quasi-static reset voltage window but below the set voltage window. The sluggish reset process in TiO2 thin film and the dependence of the reset switching time on the amplitude of the applied voltage pulse was understood on the basis of a self-accelerated thermal dissolution model of conducting filaments (CFs), where a higher temperature of the CFs owing to enhanced Joule heating at a higher applied voltage imposes faster diffusion of oxygen vacancies, resulting in a shorter reset switching time. Our results clearly indicate that fast resistive switching with switching times in hundreds of nanoseconds can be achieved in ALD-grown TiO2 thin films. This may find applications in fast non-volatile unipolar resistive switching memories.

A fast and effective method for N-doping TiO2 by post treatment with liquid ammonia: visible light photocatalysis

International Nuclear Information System (INIS)

Powell, Michael J.; Palgrave, Robert G.; Dunnill, Charles W.; Parkin, Ivan P.

2014-01-01

TiO 2 thin films prepared by sol–gel synthesis were N-doped by post treating with liquid ammonia and annealing at 500 °C. Characterisation by X-ray diffraction and Raman spectroscopy confirmed that the anatase crystal type was retained and present in all samples. Scanning electron microscopy showed that treatment with liquid ammonia had no significant effect on the film morphology. Functional testing under filtered while light conditions involving water contact angle, and the photo destruction of both Resazurin and Stearic acid showed the ammonia treated samples to be active visible light photocatalysts in contrast to the pure TiO 2 and the blank controls. X-ray Photoelectron Spectroscopy studies indicate the presence of interstitial nitrogen (N 1s = 400 eV) suggesting that the origin of the enhanced photocatalytic activity is most likely due to oxygen vacancies created by the interstitial nitrogen incorporation. This synthesis method utilises a simple, inexpensive and highly effective post treatment route to N-dope TiO 2 and produces visible light photocatalysts with potential applications in self-cleaning and healthcare environments. - Highlights: • Synthesis and characterisation of N-doped TiO 2 thin films • N-doping by a post treatment with liquid ammonia • Enhanced photocatalytic activity • Easy enhancement of current TiO 2 based technologies

Preparation of Anatase TiO2 Thin Films with (OiPr)2Ti(CH3COCHCONEt2)2 Precursor by MOCVD

International Nuclear Information System (INIS)

Bae, Byoung Jae; Seo, Won Seok; Miah, Arzu; Park, Joon T.; Lee, Kwang Yeol; Kim, Keun Chong

2004-01-01

The reaction of titanium tetraisopropoxide with 2 equiv of N,N-diethyl acetoacetamide affords Ti(O i Pr) 2 (CH 3 COCHCONEt 2 ) 2 (1) as colorless crystals in 80% yield. Compound 1 is characterized by spectroscopic (Mass and 1 H/ 13 C NMR) and microanalytical data. Molecular structure of 1 has been determined by a single crystal X-ray diffraction study, which reveals that it is a monomeric, cis-diisopropoxide and contains a six coordinate Ti(IV) atom with a cis(CONEt 2 ), trans(COCH 3 ) configuration (1a) in a distorted octahedral environment. Variable-temperature 1 H NMR spectra of 1 indicate that it exists as an equilibrium mixture of cis, trans (1a) and cis, cis (1b) isomers in a 0.57 : 0.43 ratio at -20 .deg. C in toluene-d 8 solution. Thermal properties of 1 as a MOCVD precursor for titanium dioxide films have been evaluated by thermal gravimetric analysis and vapor pressure measurement. Thin films of pure anatase titanium dioxide (after annealing above 500 .deg. C under oxygen) have been grown on Si(100) with precursor 1 in the substrate temperature range of 350- 500 .deg. C using a bubbler-based MOCVD method

The Photocatalytic Activity and Compact Layer Characteristics of TiO2 Films Prepared Using Radio Frequency Magnetron Sputtering

Directory of Open Access Journals (Sweden)

H. C. Chang

2014-01-01

Full Text Available TiO2 compact layers are used in dye-sensitized solar cells (DSSCs to prevent charge recombination between the electrolyte and the transparent conductive substrate (indium tin oxide, ITO; fluorine-doped tin oxide, FTO. Thin TiO2 compact layers are deposited onto ITO/glass by means of radio frequency (rf magnetron sputtering, using deposition parameters that ensure greater photocatalytic activity and increased DSSC conversion efficiency. The photoinduced decomposition of methylene blue (MB and the photoinduced hydrophilicity of the TiO2 thin films are also investigated. The photocatalytic performance characteristics for the deposition of TiO2 films are improved by using the Grey-Taguchi method. The average transmittance in the visible region exceeds 85% for all samples. The XRD patterns of the TiO2 films, for sol-gel with spin coating of porous TiO2/TiO2 compact/ITO/glass, show a good crystalline structure. In contrast, without the TiO2 compact layer (only porous TiO2, the peak intensity of the anatase (101 plane in the XRD patterns for the TiO2 film has a lower value, which demonstrates inferior crystalline quality. With a TiO2 compact layer to prevent charge recombination, a higher short-circuit current density is obtained. The DSSC with the FTO/glass and Pt counter electrode demonstrates the energy conversion efficiency increased.

TiO2 Nanotubes on Transparent Substrates: Control of Film Microstructure and Photoelectrochemical Water Splitting Performance

Directory of Open Access Journals (Sweden)

Matus Zelny

2018-01-01

Full Text Available Transfer of semiconductor thin films on transparent and or flexible substrates is a highly desirable process to enable photonic, catalytic, and sensing technologies. A promising approach to fabricate nanostructured TiO2 films on transparent substrates is self-ordering by anodizing of thin metal films on fluorine-doped tin oxide (FTO. Here, we report pulsed direct current (DC magnetron sputtering for the deposition of titanium thin films on conductive glass substrates at temperatures ranging from room temperature to 450 °C. We describe in detail the influence that deposition temperature has on mechanical, adhesion and microstructural properties of titanium film, as well as on the corresponding TiO2 nanotube array obtained after anodization and annealing. Finally, we measure the photoelectrochemical water splitting activity of different TiO2 nanotube samples showing that the film deposited at 150 °C has much higher activity correlating well with the lower crystallite size and the higher degree of self-organization observed in comparison with the nanotubes obtained at different temperatures. Importantly, the film showing higher water splitting activity does not have the best adhesion on glass substrate, highlighting an important trade-off for future optimization.

Oriented growth of Sr n+1Ti n O3n+1 Ruddlesden-Popper phases in chemical solution deposited thin films

International Nuclear Information System (INIS)

Gutmann, Emanuel; Levin, Alexandr A.; Reibold, Marianne; Mueller, Jan; Paufler, Peter; Meyer, Dirk C.

2006-01-01

Oriented thin films of perovskite-related Sr n +1 Ti n O 3 n +1 Ruddlesden-Popper phases (n=1, 2, 3) were grown on (001) single-crystalline SrTiO 3 substrates. Preparation of the films was carried out by wet chemical deposition from metalorganic Sr-Ti solutions (rich in Sr) and subsequent conversion into the crystalline state by thermal treatment in air atmosphere at a maximum temperature of 700 deg. C. Solutions were prepared by a modified Pechini method. The films were investigated by wide-angle X-ray scattering and high-resolution transmission electron microscopy. The phase content of powders prepared from the dried solutions and annealed under similar conditions differed from that present in the films, i.e. only polycrystalline SrTiO 3 was detected together with oxides of Ti and Sr. - Graphical abstract: Cross-sectional image of an oriented chemical solution deposited thin film obtained by high-resolution transmission electron microscopy. Periodical spacings corresponding to SrTiO 3 substrate (right) and Sr 2 TiO 4 Ruddlesden-Popper phase (n=1) film region (left) are marked

Crystal Structure And Optical Properties Of TiO2 Thin Films Prepared By Reactive RF Magnetron Sputtering

Directory of Open Access Journals (Sweden)

Goto S.

2015-06-01

Full Text Available In sputtering deposition process of TiO2, metal Ti or sintered TiO2 target is used as deposition source. In this study, we have compared the characteristic of target materials. When TiO2 target was used, stoichiometric TiO2 films was deposited under the Ar atmosphere containing 1.0% of oxygen. The highest sputtering rate under this atmosphere was 3.9nm/min at 3.4W/cm2. But, sintered TiO2 target is fragile and cannot endure higher density of input power than 3.4W/cm2. On the other hand, Ti target needs higher oxygen concentration (8% in sputtering gas atmosphere for obtaining rutile/anatase. Even though Ti target can be input twice power density of 7.9W/cm2, the highest deposition rate for Ti target was 1.4/nm, which was ~35% of the highest rate for TiO2 target. Then we have study out the composite target consisting of Ti plate and TiO2 chips. Using the composite target, stoichiometric TiO2 films were prepared in the rate of 9.6nm/min at 6.8 W/cm2 under the atmosphere of Ar/2.5%O2. Furthermore, we have found that the TiO2 films obtained from the composite target consisted of about 100% anatase, whereas TiO2 films obtained from other target have rutile dominant structure. The optical band gap energy of the film is determined by using the Tauc plot. The calculated band gap energies for the films deposited by Ti target and composite target were 2.95 and 3.24eV, which are equivalent to that of rutile and anatase structure, respectively.

Optimization of time on CF_4/O_2 etchant for inductive couple plasma reactive ion etching of TiO_2 thin film

International Nuclear Information System (INIS)

Adzhri, R.; Fathil, M. F. M.; Ruslinda, A. R.; Gopinath, Subash C. B.; Voon, C. H.; Foo, K. L.; Nuzaihan, M. N. M.; Azman, A. H.; Zaki, M.; Arshad, M. K. Md.; Hashim, U.; Ayub, R. M.

2016-01-01

In this work, we investigate the optimum etching of titanium dioxide (TiO_2) using inductive couple plasma reactive ion etching (ICP-RIE) on our fabricated devices. By using a combination of CF_4/O_2 gases as plasma etchant with ratio of 3:1, three samples of TiO_2 thin film were etched with different time duration of 10 s, 15 s and 20 s. The ion bombardment of CF_4 gases with plasma enhancement by O_2 gas able to break the oxide bond of TiO_2 and allow anisotropic etch profile with maximum etch rate of 18.6 nm/s. The sample was characterized by using optical profilometer to determine the depth of etched area and scanning electron microscopy (SEM) for etch profile characterization.

TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

Science.gov (United States)

Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

2015-02-01

The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

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.

Suppressing the Photocatalytic Activity of TiO2 Nanoparticles by Extremely Thin Al2O3 Films Grown by Gas-Phase Deposition at Ambient Conditions

NARCIS (Netherlands)

Guo, J.; Bui, H.V.; Valdesueiro Gonzalez, D.; Yuan, Shaojun; Liang, Bin; van Ommen, J.R.

2018-01-01

This work investigated the suppression of photocatalytic activity of titanium dioxide (TiO2) pigment powders by extremely thin aluminum oxide (Al2O3) films deposited via an atomic-layer-deposition-type process using trimethylaluminum (TMA) and H2O as precursors. The deposition was performed on

Reflection Enhancement Using TiO2/SiO2 Bilayer Films Prepared by Cost-Effective Sol-gel Method

Directory of Open Access Journals (Sweden)

R. Ajay Kumar

2017-04-01

Full Text Available Multilayer dielectric thin film structure has been demanded for its application in optoelectronic devices such as optical waveguides, vertical cavity surface-emitting devices, biosensors etc. In this paper, we present the fabrication and characterization of bilayer thin films of TiO2/SiO2 using sol-gel spin coating method. Ellipsometer measurement showed refractive index values 1.46, 2.1 corresponding to the SiO2 and TiO2 films respectively. The FTIR transmittance peaks observed at ~970 cm-1, ~1100 cm-1 and ~1400 cm-1 are attributed to the Ti-O-Si, Si-O-Si and Ti-O-Ti bonds respectively. Maximum reflectance is observed from two bilayer film structure which can be further optimized to get the high reflection to a broad wavelength range.

Single-Nanoparticle Photoelectrochemistry at a Nanoparticulate TiO2 -Filmed Ultramicroelectrode.

Science.gov (United States)

Peng, Yue-Yi; Ma, Hui; Ma, Wei; Long, Yi-Tao; Tian, He

2018-03-26

An ultrasensitive photoelectrochemical method for achieving real-time detection of single nanoparticle collision events is presented. Using a micrometer-thick nanoparticulate TiO 2 -filmed Au ultra-microelectrode (TiO 2 @Au UME), a sub-millisecond photocurrent transient was observed for an individual N719-tagged TiO 2 (N719@TiO 2 ) nanoparticle and is due to the instantaneous collision process. Owing to a trap-limited electron diffusion process as the rate-limiting step, a random three-dimensional diffusion model was developed to simulate electron transport dynamics in TiO 2 film. The combination of theoretical simulation and high-resolution photocurrent measurement allow electron-transfer information of a single N719@TiO 2 nanoparticle to be quantified at single-molecule accuracy and the electron diffusivity and the electron-collection efficiency of TiO 2 @Au UME to be estimated. This method provides a test for studies of photoinduced electron transfer at the single-nanoparticle level. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elaboration and Characterization of TiO2 and Study of the Influence of The Number of Thin Films on the Methylene Blue Adsorption Rate

Science.gov (United States)

Madoui, Karima; Medjahed, Aicha; Hamici, Melia; Djamila, Abdi; Boudissa, Mokhtar

2018-05-01

Thin films of titanium oxide (TiO2) deposited on glass substrates were fabricated by using the sol-gel route. The realization of these thin layers was made using the dip-coating technique with a solution of titanium isopropoxyde as a precursor. The samples prepared with different numbers of deposited layers were annealed at 400 ° C for 2 hours. The main purposes of this work were investigations of both the effect of the number of thin TiO2 layers on the crystal structure of the anatase form first and, their ability to adsorb the solution of methylene blue in order to make colored filters from a photocatalytic process. The deposited titanium-oxide layers were characterized by using various techniques: namely, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV-Visible spectrometry. The result obtained by using the XRD technique showed the appearance of an anatase phase, as was confirmed by using Raman spectroscopy. The AFM surface analysis allowed the surface topography to be characterized and the surface roughness to be measured, which increased with increasing number of layers. The UV-Visible spectra showed that the TiO2 films had a good transmittance varying from 65% to 95% according to the number of layers. The gap energy varied as a function of the number of deposited layers. The as deposited TiO2 layers were tested as a photocatalyst towards the adsorption of methylene blue dye. The results obtained during this study showed that the adsorption capacity varied according to the number of deposited thin layers and the exposing duration to ultraviolet (UV) light. The maximum absorption rate of the dye was obtained for the two-layer sample. Seventy-two hours of irradiation allowed the adsorption intensity of the dye to be maximized for two-layer films.

Preparation and switching kinetics of Pb(Zr, Ti)O3 thin films deposited by reactive sputtering

International Nuclear Information System (INIS)

Hase, Takashi; Shiosaki, Tadashi

1991-01-01

Ferroelectric Pb(Zr, Ti)O 3 [PZT] thin films have been prepared on Pt/Ti/SiO 2 /Si and Pt/SiO 2 /Si substrates using the reactive sputtering method with a metal composite target. The (111)-oriented PZT (80/20) thin films with a perovskite structure have been obtained at a substrate temperature of 595degC on highly (111)-oriented Pt films formed on SiO 2 /Si substrates. When an 8 V pulse sequence was applied to a 265 nm-thick film with an electrode area of 50 x 50 μm 2 , the switching time and the switched charge density measured were 20 ns and 10 μC/cm 2 , respectively. The switching time was strongly dependent on the electrode area. (author)

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

International Nuclear Information System (INIS)

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

2012-01-01

Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

Enhanced photoelectrochemical properties of F-containing TiO2 sphere thin film induced by its novel hierarchical structure

International Nuclear Information System (INIS)

Dong Xiang; Tao Jie; Li Yingying; Zhu Hong

2009-01-01

The novel nanostructured F-containing TiO 2 (F-TiO 2 ) sphere was directly synthesized on the surface of Ti foil in the solution of NH 4 F and HCl by one-step hydrothermal approach under low-temperature condition. The samples were characterized respectively by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the F-TiO 2 sphere was hierarchical structure, which composed of porous octahedron crystals with one truncated cone, leading to a football-like morphology. XPS results indicated that F - anions were just physically adsorbed on the surface of TiO 2 microspheres. The studies on the optical properties of the F-TiO 2 were carried out by UV-vis light absorption spectrum. The surface fluorination of the spheres, the unique nanostructure induced accessible macropores or mesopores, and the increased light-harvesting abilities were crucial for the high photoelectrochemical activity of the synthesized F-TiO 2 sphere for water-splitting. The photocurrent density of the F-TiO 2 sphere thin film was more than two times than that of the P25 thin film. Meanwhile, a formation mechanism was briefly proposed. This approach could provide a facile method to synthesize F-TiO 2 microsphere with a special morphology and hierarchical structure in large scale.

Annealing time dependence of the physical, electrical and pH response characteristics of spin coated TiO2 thin films

International Nuclear Information System (INIS)

Zulkefle, M A; Rahman, R A; Yusoff, K A; Herman, S H; Abdullah, W F H; Rusop, M

2015-01-01

Titanium dioxide (TiO 2 ) thin film was deposited on indium tin oxide (ITO) substrate and used as sensing membrane of EGFET pH sensor. The thin film was fabricated using sol- gel spin coating method. All samples were annealed at 400 °C but the annealing time was varied. This is done to study the effects of annealing time on physical and electrical properties of titanium dioxide thin film. The sensitivity of each sample towards H + ion was measured and result shows that sample annealed for 45 minutes has the highest sensitivity (52.6 mV/pH). It is found that increasing annealing duration will increase the pH sensitivity but a limit will be reached at certain point. Longer annealing processes done beyond this point will results in lower pH sensitivity. (paper)

Tuning the Phase and Microstructural Properties of TiO2 Films Through Pulsed Laser Deposition and Exploring Their Role as Buffer Layers for Conductive Films

Science.gov (United States)

Agarwal, S.; Haseman, M. S.; Leedy, K. D.; Winarski, D. J.; Saadatkia, P.; Doyle, E.; Zhang, L.; Dang, T.; Vasilyev, V. S.; Selim, F. A.

2018-04-01

Titanium oxide (TiO2) is a semiconducting oxide of increasing interest due to its chemical and thermal stability and broad applicability. In this study, thin films of TiO2 were deposited by pulsed laser deposition on sapphire and silicon substrates under various growth conditions, and characterized by x-ray diffraction (XRD), atomic force microscopy (AFM), optical absorption spectroscopy and Hall-effect measurements. XRD patterns revealed that a sapphire substrate is more suitable for the formation of the rutile phase in TiO2, while a silicon substrate yields a pure anatase phase, even at high-temperature growth. AFM images showed that the rutile TiO2 films grown at 805°C on a sapphire substrate have a smoother surface than anatase films grown at 620°C. Optical absorption spectra confirmed the band gap energy of 3.08 eV for the rutile phase and 3.29 eV for the anatase phase. All the deposited films exhibited the usual high resistivity of TiO2; however, when employed as a buffer layer, anatase TiO2 deposited on sapphire significantly improves the conductivity of indium gallium zinc oxide thin films. The study illustrates how to control the formation of TiO2 phases and reveals another interesting application for TiO2 as a buffer layer for transparent conducting oxides.

Synthesis and characterization of anatase-TiO2 thin films

International Nuclear Information System (INIS)

Sankapal, B.R.; Lux-Steiner, M.Ch.; Ennaoui, A.

2005-01-01

A new and effective method for the preparation of nanocrystalline TiO 2 (anatase) thin films is presented. This method is based on the use of peroxo-titanium complex as a single precursor. Post-annealing treatment is necessary to convert the deposited amorphous film into TiO 2 (anatase) phase. The films obtained are uniform, compact and free of pinholes. A wide range of techniques are used for characterization, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDAX) and UV-Vis-NIR spectrophotometer. Glass, indium-doped tin oxide (ITO) and quartz are used as substrates. TiO 2 (anatase) phase with (1 0 1) preferred orientation is obtained for the films. Byproduct (collected powder) consists of the same crystal structure. The optical measurement reveals the indirect bandgap of 3.2 eV

Synthesis and characterization of anatase-TiO 2 thin films

Science.gov (United States)

Sankapal, B. R.; Lux-Steiner, M. Ch.; Ennaoui, A.

2005-01-01

A new and effective method for the preparation of nanocrystalline TiO 2 (anatase) thin films is presented. This method is based on the use of peroxo-titanium complex as a single precursor. Post-annealing treatment is necessary to convert the deposited amorphous film into TiO 2 (anatase) phase. The films obtained are uniform, compact and free of pinholes. A wide range of techniques are used for characterization, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDAX) and UV-Vis-NIR spectrophotometer. Glass, indium-doped tin oxide (ITO) and quartz are used as substrates. TiO 2 (anatase) phase with (1 0 1) preferred orientation is obtained for the films. Byproduct (collected powder) consists of the same crystal structure. The optical measurement reveals the indirect bandgap of 3.2 eV.

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

International Nuclear Information System (INIS)

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

2014-01-01

TiO 2 thin films deposited by electron beam evaporation technique annealed in either O 2 or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O 2 atmosphere. While the pristine film shows a super-paramagnetic behavior, both O 2 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 O 2 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, O 2 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 O 2 annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO 2 film deposited by pulsed laser deposition (Mohanty et al., 2012 [10]). - Highlights: • TiO 2 films were deposited by e-beam evaporation technique and post annealed under O 2 /Ar at 500 °C. • The pristine film shows SPM behavior where as O 2 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 O 2 annealed film than the Ar annealed one. • The higher M s in O 2 annealed film is attributed to oxygen vacancies as well as crystallinity

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

Science.gov (United States)

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

2011-01-01

The hemocompatibility of La2O3-doped TiO2 films with different concentration prepared by radio frequency (RF) sputtering was studied. The microstructures and blood compatibility of TiO2 films were investigated by scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible optical absorption spectroscopy, respectively. With the increasing of the La2O3 concentrations, the TiO2 films become smooth, and the grain size becomes smaller. Meanwhile, the band gap of the samples increases from 2.85 to 3.3 eV with increasing of the La2O3 content in TiO2 films from 0 to 3.64%. La2O3-doped TiO2 films exhibit n-type semiconductor properties due to the existence of Ti2+ and Ti3+. The mechanism of hemocompatibility of TiO2 film doped with La2O3 was analyzed and discussed. PMID:22162671

Effects of atomic oxygen on titanium dioxide thin film

Science.gov (United States)

Shimosako, Naoki; Hara, Yukihiro; Shimazaki, Kazunori; Miyazaki, Eiji; Sakama, Hiroshi

2018-05-01

In low earth orbit (LEO), atomic oxygen (AO) has shown to cause degradation of organic materials used in spacecrafts. Similar to other metal oxides such as SiO2, Al2O3 and ITO, TiO2 has potential to protect organic materials. In this study, the anatese-type TiO2 thin films were fabricated by a sol-gel method and irradiated with AO. The properties of TiO2 were compared using mass change, scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmittance spectra and photocatalytic activity before and after AO irradiation. The results indicate that TiO2 film was hardly eroded and resistant against AO degradation. AO was shown to affects only the surface of a TiO2 film and not the bulk. Upon AO irradiation, the TiO2 films were slightly oxidized. However, these changes were very small. Photocatalytic activity of TiO2 was still maintained in spite of slight decrease upon AO irradiation, which demonstrated that TiO2 thin films are promising for elimination of contaminations outgassed from a spacecraft's materials.

Preparation of Pb(Zr, Ti)O3 Thin Films by Plasma-Assisted Sputtering

Science.gov (United States)

Hioki, Tsuyoshi; Akiyama, Masahiko; Ueda, Tomomasa; Onozuka, Yutaka; Suzuki, Kouji

1999-09-01

A novel plasma-assisted RF magnetron sputtering system with an immersed coil antenna between a target and a substrate was applied for preparing Pb(Zr, Ti)O3 (PZT) thin films. The antenna enabled the generation of inductively coupled plasma (ICP) independently of the target RF source. The plasma assisted by the antenna resulted in the changes of ion fluxes and these energy distributions irradiating to the substrate. The crystalline phase of the deposited PZT thin films was occupied by the perovskite phase depending on the antenna power. In addition, a high deposition rate, modified uniformity of film thickness, and a dense film structure with large columnar grains were obtained as a result of effects of the assisted plasma. The application of the plasma-assisted sputtering method may enable the preparation of PZT thin films that haveexcellent properties.

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

International Nuclear Information System (INIS)

Conde-Gallardo, A.; Guerrero, M.; Castillo, N.; Soto, A.B.; Fragoso, R.; Cabanas-Moreno, J.G.

2005-01-01

Titanium dioxide thin films were deposited on crystalline silicon (100) and fused quartz substrates by spray pyrolysis (SP) of an aerosol, generated ultrasonically, of titanium diisopropoxide. The evolution of the crystallization, studied by X-ray diffraction (XRD), atomic force (AFM) and scanning electron microscopy (SEM), reflection and transmission spectroscopies, shows that the deposition process is nearly close to the classical chemical vapor deposition (CVD) technique, producing films with smooth surface and good crystalline properties. At deposition temperatures below 400 deg. C, the films grow in amorphous phase with a flat surface (roughness∼0.5 nm); while for equal or higher values to this temperature, the films develop a crystalline phase corresponding to the TiO 2 anatase phase and the surface roughness is increased. After annealing at 750 deg. C, the samples deposited on Si show a transition to the rutile phase oriented in (111) direction, while for those films deposited on fused quartz no phase transition is observed

The Effect of Normal Force on Tribocorrosion Behaviour of Ti-10Zr Alloy and Porous TiO2-ZrO2 Thin Film Electrochemical Formed

Science.gov (United States)

Dănăilă, E.; Benea, L.

2017-06-01

The tribocorrosion behaviour of Ti-10Zr alloy and porous TiO2-ZrO2 thin film electrochemical formed on Ti-10Zr alloy was evaluated in Fusayama-Mayer artificial saliva solution. Tribocorrosion experiments were performed using a unidirectional pin-on-disc experimental set-up which was mechanically and electrochemically instrumented, under various solicitation conditions. The effect of applied normal force on tribocorrosion performance of the tested materials was determined. Open circuit potential (OCP) measurements performed before, during and after sliding tests were applied in order to determine the tribocorrosion degradation. The applied normal force was found to greatly affect the potential during tribocorrosion experiments, an increase in the normal force inducing a decrease in potential accelerating the depassivation of the materials studied. The results show a decrease in friction coefficient with gradually increasing the normal load. It was proved that the porous TiO2-ZrO2 thin film electrochemical formed on Ti-10Zr alloy lead to an improvement of tribocorrosion resistance compared to non-anodized Ti-10Zr alloy intended for biomedical applications.

Spray pyrolysed Ru:TiO2 thin film electrodes prepared for electrochemical supercapacitor

Science.gov (United States)

Fugare, B. Y.; Thakur, A. V.; Kore, R. M.; Lokhande, B. J.

2018-04-01

Ru doped TiO2 thin films are prepared by using 0.06 M aqueous solution of potassium titanium oxalate (pto), and 0.005 M aqueous solution of ruthenium tri chloride (RuCl3) precursors. The deposition was carried on stainless steel (SS) by using well known ultrasonic spray pyrolysis technique (USPT) at 723° K by maintaining the spray rate 12 cc/min and compressed air flow rate 10 Lmin-1. Prepared Ru:TiO2 thin films were characterized by structurally, morphologically and electrochemically. Deposited RuO2 shows amorphous structure and TiO2 shows tetragonal crystal structure with rutile as prominent phase at very low decomposition temperature. SEM micrographs of RuO2 exhibits porous, interconnected, spherical grains type morphology and TiO2 shows porous, nanorods and nanoplates like morphology and also Ru doped TiO2 shows porous, spherical, granular and nanorods type morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The achieved highest value of specific capacitance 2692 F/g was Ru doped TiO2 electrode in 0.5 M H2SO4.

Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

Directory of Open Access Journals (Sweden)

Walter Water

2014-01-01

Full Text Available A TiO2 thin film deposited on a 90° rotated 42°45′ ST-cut quartz substrate was applied to fabricate a Love wave ultraviolet photodetector. TiO2 thin films were grown by radio frequency magnetron sputtering. The crystalline structure and surface morphology of TiO2 thin films were examined using X-ray diffraction, scanning electron microscope, and atomic force microscope. The effect of TiO2 thin film thickness on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and sensitivity of ultraviolet of devices was investigated. TiO2 thin film increases the electromechanical coupling coefficient but decreases the temperature coefficient of frequency for Love wave propagation on the 90° rotated 42°45′ ST-cut quartz. For Love wave ultraviolet photodetector application, the maximum insertion loss shift and phase shift are 2.81 dB and 3.55 degree at the 1.35-μm-thick TiO2 film.

Titanium oxynitride thin films as high-capacity and high-rate anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Chiu, Kuo-Feng; Su, Shih-Hsuan; Leu, Hoang-Jyh; Hsia, Chen-Hsien

2015-01-01

Titanium oxynitride (TiO_xN_y) was synthesized by reactive magnetron sputtering in a mixed N_2/O_2/Ar gas at ambient temperature. TiO_xN_y thin films with various amounts of nitrogen contents were deposited by varying the N_2/O_2 ratios in the background gas. The synthesized TiO_xN_y films with different compositions (TiO_1_._8_3_7N_0_._0_6_0_, TiO_1_._8_9_0N_0_._0_6_8_, TiO_1_._8_6_5N_0_._0_7_3, and TiO_1_._8_8_2N_0_._1_6_3) all displayed anatase phase, except TiO_1_._8_8_2N_0_._1_6_3. The impedances and grain sizes showed obvious variations with the nitrogen contents. A wide potential window from 3.0 V to 0.05 V, high-rate charge–discharge testing, and long cycle testing were applied to investigate the performances of synthesized TiO_xN_y and pure TiO_2 as anodes for lithium-ion batteries. These TiO_xN_y anodes can be cycled under high rates of 125 μA/cm"2 (10 °C) because of the lower charge–transfer resistance compared with the TiO_2 anode. At 10 °C the discharge capacity of the optimal TiO_xN_y composition is 1.5 times higher than that of pure TiO_2. An unexpectedly large reversible capacity of ~ 300 μAh/cm"2 μm (~ 800 mAh/g) between 1.0 V and 0.05 V was recorded for the TiO_xN_y anodes. The TiO_xN_y anode was cycled (3.0 V to 0.05 V) at 10 °C over 300 times without capacity fading while delivering a capacity of ~ 150 μAh/cm"2 μm (~ 400 mAh/g). - Highlights: • Titanium oxynitride (TiO_xN_y) thin films as anode materials were studied. • TiO_xN_y thin films with various amounts of nitrogen contents were studied_. • High rate capability of TiO_xN_y was studied.

Interfacial characteristics and dielectric properties of Ba0.65Sr0.35TiO3 thin films

International Nuclear Information System (INIS)

Quan Zuci; Zhang Baishun; Zhang Tianjin; Zhao Xingzhong; Pan Ruikun; Ma Zhijun; Jiang Juan

2008-01-01

Ba 0.65 Sr 0.35 TiO 3 (BST) thin films were deposited on Pt/Ti/SiO 2 /Si substrates by radio frequency magnetron sputtering technique. X-ray photoelectron spectroscopy (XPS) depth profiling data show that each element component of the BST film possesses a uniform distribution from the outermost surface to subsurface, but obvious Ti-rich is present to BST/Pt interface because Ti 4+ cations are partially reduced to form amorphous oxides such as TiO x (x -7 A/cm 2 at 1.23 V and lower than 5.66 x 10 -6 A/cm 2 at 2.05 V as well as breakdown strength is above 3.01 x 10 5 V/cm

Observation of Significant enhancement in the efficiency of a DSSC by InN nanoparticles over TiO 2-nanoparticle films

Science.gov (United States)

Wang, Tsai-Te; Raghunath, P.; Lu, Yun-Fang; Liu, Yu-Chang; Chiou, Chwei-Huawn; Lin, M. C.

2011-06-01

We have studied the effect of InN deposited over TiO2 nanoparticle (NP) films on the performance of dye-sensitized solar cells (DSSCs) using N3 dye with I/I3- electrolyte. A 10-20% increase in efficiency was observed for InN deposited, N3 sensitized 5-8.5 μm thick TiO2 films as compared to similar non-treated films. The deposition of InN was carried out in the temperature range of 573-723 K organometallic chemical vapor deposition (OMCVD). Spectral shifts and DFT calculations with a model anchoring group (R‧COOH) both suggest binding of the N3 dye directly to both InN and the InN/TiO2 sites.

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

International Nuclear Information System (INIS)

Kim, Sang Bum; Lee, Jun Yub; Kim, Gyung Soo; Hong, Sung Chang

2009-01-01

The present paper examined the photocatalytic degradation (PCD) of gas-phase trichloroethylene (TCE) over thin-film TiO 2 . A large-scale treatment of TCE was carried out using scale-up continuous flow photo-reactor in which nine reactors were arranged in parallel and series. The parallel or serial arrangement is a significant factor to determine the special arrangement of whole reactor module as well as to compact the multi-modules in a continuous flow reactor. The conversion of TCE according to the space time was nearly same for parallel and serial connection of the reactors.

Fine control of the amount of preferential <001> orientation in DC magnetron sputtered nanocrystalline TiO2 films

International Nuclear Information System (INIS)

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

2014-01-01

Different crystal facets of anatase TiO 2 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 TiO 2 thin films were deposited by reactive DC magnetron sputtering in Ar/O 2 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 <001> 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 TiO 2 films prepared by sputtering methods

500 keV Ar2+ ion irradiation induced anatase to brookite phase transformation and ferromagnetism at room temperature in TiO2 thin films

Science.gov (United States)

Bharati, B.; Mishra, N. C.; Kanjilal, D.; Rath, Chandana

2018-01-01

In our earlier report, where we have demonstrated ferromagnetic behavior at room temperature (RT) in TiO2 thin films deposited through electron beam evaporation technique followed by annealing either in Ar or O2 atmosphere [Mohanty et al., Journal of Magnetism and Magnetic Materials 355 (2014) 240-245], here we have studied the evolution of structure and magnetic properties after irradiating the TiO2 thin films with 500 keV Ar2+ ions. The pristine film while exhibits anatase phase, the films become amorphous after irradiating at fluence in the range 1 × 1014 to 1 × 1016 ions/cm2. Increasing the fluence up to 5 × 1016 ions/cm2, amorphous to crystalline phase transformation occurs and the structure becomes brookite. Although anatase to rutile phase transformation is usually reported in literatures, anatase to brookite phase transformation is an unusual feature which we have reported here for the first time. Such anatase to brookite phase transformation is accompanied with grain growth without showing any change in film thickness evidenced from Rutherford's Back Scattering (RBS) measurement. From scanning probe micrographs (SPM), roughness is found to be more in amorphous films than in the crystalline ones. Anatase to brookite phase transformation could be realized by considering the importance of intermediate amorphous phase. Because due to amorphous phase, heat deposited by energetic ions are localized as dissipation of heat is less and as a result, the localized region crystallizes in brookite phase followed by grain growth as observed in highest fluence. Further, we have demonstrated ferromagnetic behavior at RT in irradiated films similar to pristine one, irrespective of their phase and crystallinity. Origin for room temperature ferromagnetism (RTFM) is attributed to the presence of oxygen vacancies which is confirmed by carrying out XPS measurement.

Band-gap narrowing of TiO2 films induced by N-doping

International Nuclear Information System (INIS)

Nakano, Y.; Morikawa, T.; Ohwaki, T.; Taga, Y.

2006-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 o C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from X-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at 1.18 and 2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N-doping and contributes to band-gap narrowing by mixing with the O 2p valence band

Influence of the substrate on the morphological evolution of gold thin films during solid-state dewetting

International Nuclear Information System (INIS)

Nsimama, Patrick D.; Herz, Andreas; Wang, Dong; Schaaf, Peter

2016-01-01

Highlights: • Dewetting of thin gold films is faster on TiO_2 than on SiO_2. • Dewetting of thin gold films is faster on amorphous TiO_2 than on crystalline TiO_2. • The kinetics is attributed to the energy of adhesion. • The morphology of thin Au films deposited on TiO_2 substrates is different to those deposited on SiO_2 substrates. • The dewetting activation energy of Au films deposited on crystalline substrates was higher than the activation energy of Au nanofilms deposited on amorphous TiO_2 substrates. - Abstract: The evolution of electron-beam evaporated Au thin films deposited on crystalline TiO_2 (c-TiO_2) and amorphous TiO_2 (a-TiO_2) as well as amorphous SiO_2 substrates are investigated. The kinetic of dewetting is clearly dependent on the type of substrate and is faster on TiO_2 substrates than on SiO_2 substrates. This difference can result from the difference in adhesion energy. Furthermore, the kinetic of dewetting is faster on a-TiO_2 than on c-TiO_2, possibly due to the crystallization of TiO_2 during annealing induced dewetting process. The morphologies of dewetted Au films deposited on crystalline TiO_2 are characterized by branched holes. The XRD patterns of the Au films deposited on TiO_2 substrates constituted peaks from both metallic Au and anatase TiO_2. The activation energy of Au films deposited on crystalline TiO_2 substrates was higher than that that of the films deposited on amorphous TiO_2 substrates.

Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

Science.gov (United States)

Mohapatra, A. K.; Nayak, J.

2018-05-01

Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

Epitaxial Fe16N2 thin film on nonmagnetic seed layer

Science.gov (United States)

Hang, Xudong; Zhang, Xiaowei; Ma, Bin; Lauter, Valeria; Wang, Jian-Ping

2018-05-01

Metastable α″ -Fe16N2 has attracted much interest as a candidate for rare-earth-free hard magnetic materials. We demonstrate that Fe16N2 thin films were grown epitaxially on Cr seed layers with MgO (001) substrates by facing-target sputtering. Good crystallinity with the epitaxial relation MgO (001 )[110 ] ∥ Cr (001 )[100 ] ∥ Fe16N2 (001 )[100 ] was obtained. The chemical order parameter, which quantifies the degree of N ordering in the Fe16N2 (the N-disordered phase is α' -Fe8N martensite), reaches 0.75 for Cr-seeded samples. Cr has a perfect lattice constant match with Fe16N2, and no noticeable strain can be assigned to Fe16N2. The intrinsic saturation magnetization of this non-strained Fe16N2 thin film at room temperature is determined to be 2.31 T by polarized neutron reflectometry and confirmed with vibrating sample magnetometry. Our work provides a platform to directly study the magnetic properties of high purity Fe16N2 films with a high order parameter.

Preparation and properties of TiO2 films by complexing agent-assisted sol-gel method. Yuki haiishi wo mochiita sol gel ho ni yoru TiO2 usumaku no sakusei to seishitsu

Energy Technology Data Exchange (ETDEWEB)

Nishide, T [Nissan Motor Co. Ltd., Tokyo (Japan); Mizukami, F [National Chemical Laboratory for Industry, Tsukuba (Japan)

1992-09-01

In order to control optical properties of TiO2 thin films, the TiO2 films were prepared by the sol-gel method using glycols or their ether derivatives as organic ligands to study the effect of the organic ligands on the refractive indices and crystal phases. Samples were prepared as follows: Organic ligand was added into the ethanol solution of Ti(O-iso-pr) 4, and aqueous nitric acid solution was added after reflux, and sol obtained by subsequent reflux was applied on soda lime glass or silicon wafer substrates, which were baked at 400 to 900 centigrade. Three kinds of ligand such as 2-(2-methoxyethoxy) ethanol were used. Measured items are the film thickness, thermal characteristics, crystal phase and refractive indices of thin films. The key points are as follows: In case of TiO2 thin films on the soda lime glass substrate, the changing pattern of refractive indices by temperature changes with the kind of ligand used and further the peak strength of anatase changes with the kind of ligand used. In case of silicon wafer substrates, the peak strength of anatase and rutile changes with the kind of ligand. The refractive indices and crystal phase can be controlled by properly using the ligand. 7 refs., 11 figs.

n-Type Conductivity of Cu2O Thin Film Prepared in Basic Aqueous Solution Under Hydrothermal Conditions

Science.gov (United States)

Ursu, Daniel; Miclau, Nicolae; Miclau, Marinela

2018-03-01

We report for the first time in situ hydrothermal synthesis of n-type Cu2O thin film using strong alkaline solution. The use of copper foil as substrate and precursor material, low synthesis temperature and short reaction time represent the arguments of a new, simple, inexpensive and high field synthesis method for the preparation of n-type Cu2O thin film. The donor concentration of n-type Cu2O thin film obtained at 2 h of reaction time has increased two orders of magnitude than previous reported values. We have demonstrated n-type conduction in Cu2O thin film prepared in strong alkaline solution, in the contradiction with the previous works. Based on experimental results, the synthesis mechanism and the origin of n-type photo-responsive behavior of Cu2O thin film were discussed. We have proposed that the unexpected n-type character could be explained by H doping of Cu2O thin film in during of the hydrothermal synthesis that caused the p-to-n conductivity-type conversion. Also, this work raises new questions about the origin of n-type conduction in Cu2O thin film, the influence of the synthesis method on the nature of the intrinsic defects and the electrical conduction behavior.

Semi-transparent ordered TiO_2 nanostructures prepared by anodization of titanium thin films deposited onto the FTO substrate

International Nuclear Information System (INIS)

Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Skowroński, Łukasz; Karczewski, Jakub; Siuzdak, Katarzyna

2016-01-01

Highlights: • High quality titanium coatings were doposited using industrial magnetron sputtering equipment. • Semi-transparent TiO_2 were prepared via anodization realized in various conditions. • Depending on electrolyte type, ordered tubular or porous TiO_2 layers were obtained. • Prepared material can act as semiconducting layer in photovoltaic cells. - Abstract: In a significant amount of cases, the highly ordered TiO_2 nanotube arrays grow through anodic oxidation of a titanium metal plate immersed in electrolyte containing fluoride ions. However, for some practical applications, e.g. solar cells or electrochromic windows, the semi-transparent TiO_2 formed directly on the transparent, conductive substrate is very much desired. This work shows that high-quality Ti coating could be formed at room temperature using an industrial magnetron sputtering system within 50 min. Under optimized conditions, the anodization process was performed on 2 μm titanium films deposited onto the FTO (fluorine-tin-oxide) support. Depending on the electrolyte type, highly ordered tubular or porous titania layers were obtained. The fabricated samples, after their thermal annealing, were investigated using scanning electron microscopy, Raman spectroscopy and UV–vis spectroscopy in order to investigate their morphology, crystallinity and absorbance ability. The photocurrent response curves indicate that materials are resistant to the photocorrosion process and their activity is strongly connected to optical properties. The most transparent TiO_2 films were fabricated when Ti was anodized in water electrolyte, whereas the highest photocurrent densities (12 μA cm"−"2) were registered for titania received after Ti anodization in ethylene glycol solution. The obtained results are of significant importance in the production of thin, semi-transparent titania nanostructures on a commercial scale.

Deep-level optical spectroscopy investigation of N-doped TiO2 films

International Nuclear Information System (INIS)

Nakano, Yoshitaka; Morikawa, Takeshi; Ohwaki, Takeshi; Taga, Yasunori

2005-01-01

N-doped TiO 2 films were deposited on n + -GaN/Al 2 O 3 substrates by reactive magnetron sputtering and subsequently crystallized by annealing at 550 deg. C in flowing N 2 gas. The N-doping concentration was ∼8.8%, as determined from x-ray photoelectron spectroscopy measurements. Deep-level optical spectroscopy measurements revealed two characteristic deep levels located at ∼1.18 and ∼2.48 eV below the conduction band. The 1.18 eV level is probably attributable to the O vacancy state and can be active as an efficient generation-recombination center. Additionally, the 2.48 eV band is newly introduced by the N doping and contributes to band-gap narrowing by mixing with the O 2p valence band

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

International Nuclear Information System (INIS)

Zhao Bote; Cai Rui; Jiang Simin; Sha Yujing; Shao Zongping

2012-01-01

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

Preparation of p-type GaN-doped SnO2 thin films by e-beam evaporation and their applications in p-n junction

Science.gov (United States)

Lv, Shuliang; Zhou, Yawei; Xu, Wenwu; Mao, Wenfeng; Wang, Lingtao; Liu, Yong; He, Chunqing

2018-01-01

Various transparent GaN-doped SnO2 thin films were deposited on glass substrates by e-beam evaporation using GaN:SnO2 targets of different GaN weight ratios. It is interesting to find that carrier polarity of the thin films was converted from n-type to p-type with increasing GaN ratio higher than 15 wt.%. The n-p transition in GaN-doped SnO2 thin films was explained for the formation of GaSn and NO with increasing GaN doping level in the films, which was identified by Hall measurement and XPS analysis. A transparent thin film p-n junction was successfully fabricated by depositing p-type GaN:SnO2 thin film on SnO2 thin film, and a low leakage current (6.2 × 10-5 A at -4 V) and a low turn-on voltage of 1.69 V were obtained for the p-n junction.

Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

Science.gov (United States)

Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

2018-01-01

In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

Thin film nano-photocatalyts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B  =  Fe, Mn, and Co)

Science.gov (United States)

Loc Luu, Cam; Thuy Van Nguyen, Thi; Nguyen, Tri; Nguyen, Phung Anh; Hoang, Tien Cuong; Ha, Cam Anh

2018-03-01

By dip-coating technique the thin films of nano-photocatalysts TiO2, Cr-doped TiO2, LaBO3 perovskites (B  =  Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, TGA, Raman and UV-vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ  =  365 nm) and LED lamps (λ  =  400-510 nm). The obtained results showed that TiO2 and TiO2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10-100 nm. Doping TiO2 with 0.1%mol Cr2O3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (λ  =  622 nm). LaBO3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8-40 nm, a BET surface area of 17.6-32.7 m2 g-1 and band gap energy of 1.87-2.20 eV. UiO66-NH2 was obtained in the ball shape of 100-200 nm, a BET surface area of 576 m2 g-1 and a band gap energy of 2.83 eV. The low band gap energy nano-photocatalysts based on Cr-doped TiO2 and LaBO3 perovskites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV-vis light. Perovskite LaFeO3 and Cr-TiO2 thin films were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene/g cat.

Cathodic electrochemical deposition of Magnéli phases TinO2n−1 thin films at different temperatures in acetonitrile solution

International Nuclear Information System (INIS)

Ertekin, Zeliha; Tamer, Uğur; Pekmez, Kadir

2015-01-01

Highlights: • TiO x films were prepared by cathodic electrodeposition in acetonitrile. • One-step electrodeposition of TiO x films without heat treatment process. • Different crystalline Ti n O 2n−1 films (γTi 3 O 5 , λTi 3 O 5 , Ti 4 O 7 , Ti 5 O 9 ) were obtained. - Abstract: The Magnéli phase titanium oxide films prepared by cathodic electrodeposition on indium–tin-oxide coated glass substrates from saturated peroxo-titanium solution in acetonitrile. Electrodeposited brownish semi-conductor thin films were identified via X-ray diffraction, Raman spectroscopy, UV–vis spectroscopy and scanning electron microscopy (SEM). The effects of different potentials and temperatures on the crystallinity of the thin films have been discussed. Ti 3 O 5 , Ti 4 O 7 and Ti 5 O 9 as the most favorable forms of the Ti n O 2n−1 were electrodeposited on ITO electrode at electrochemical deposition potentials and different temperatures. The present investigation reveals that the electrochemical deposition of crystalline Ti n O 2n−1 films by a simple one-step electrodeposition method (without any heat treatment) in acetonitrile solution is possible and very promising as a preparation method for electrochemical applications

P-MoS2 / n-CdS thin film heterojunction

International Nuclear Information System (INIS)

El Maliki, H.; Gourmelon, E.; Bernede, J.C.; Pouzet, J.; Mebarki, M.; Khelil, A.; Zoaeter, M.

1999-01-01

Full text.Layered transition metal dichacolgenides such as MoS 2 are semiconductors that can be good candidates for solar energy conversion. Photo-electrochemical cells based on single crystals have achieved and efficiency of 17% (1). However, up to day, no solid rectifying contact has been put in evidence in the case of MoS 2 thin films.. Recently we have shown that such high crystalline quality MoS 2 films can be obtained onto textured tungsten slides. This allowed to try to grow sandwich rectifying structures. The bottom electrode will be W, MoS 2 being p-type, the n type film used was CdS and the upper electrode was indium. W foils textured along the (h00) direction were used as substrate and bottom electrode. The use of a W (textured) substrate induces the texturation of the MoS 2 films along the (001) direction when after evaporation of the constituents the films were annealed at T=1073 K for half an hour under argon atmosphere. Upon the MoS 2 a CdS thin film was deposited by chemical bath deposition (CBD). CdS thin films were prepared classically from a solution of cadmium sulfate, thiourea in hydrazine and ammonia. Ammonia was used adjust the solution pH to a value between 9 and 10. Bath temperature has been held constant at 343 K. Thin deposit films of CdS were yellow colored. They were constituted of an homogenous and adherent layer with a thickness of about 100 nm. It has been shown by x-ray diffraction the they were crystallized in their hexagonal structure. At least an indium film was deposited in order to achieve the structure M/MoS 2 p/CdSn/M. In order to check the equality of the W/MoS 2 contact, W/MoS 2 /W samples were also carried out by sputtering deposition of the tungsten upper electrode (300 nm thick). The thickness of the MoS 2 layers was about 500 nm. The J-V characteristics of a W/MoS 2 /W sample are ohmic. Moreover the resistance deduced from the slope ΔV/ΔI increases when the temperature decreases, which shows that there is not any

Effect of the RE (RE = Eu, Er) doping on the structural and textural properties of mesoporous TiO2 thin films obtained by evaporation induced self-assembly method

International Nuclear Information System (INIS)

Borlaf, Mario; Caes, Sebastien; Dewalque, Jennifer; Colomer, María Teresa; Moreno, Rodrigo; Cloots, Rudi; Boschini, Frederic

2014-01-01

Polymeric sol–gel route has been used for the preparation of TiO 2 and RE 2 O 3– TiO 2 (RE = Eu, Er) mesoporous thin films by evaporation induced self-assembly method using Si (100) as a substrate. The influence of the relative humidity (RH) on the preparation of the film has been studied being necessary to work under 40% RH in order to obtain homogeneous and transparent thin films. The films were annealed at different temperatures until 900 °C/1 h and the anatase crystallization and its crystal size evolution were followed by low angle X-ray diffraction. Neither the anatase–rutile transition nor the formation of other compounds was observed in the studied temperature range. Ellipsoporosimetry studies demonstrated that the thickness of the thin films did not change after calcination at 500 °C, the porosity was constant until 700 °C, the pore size increased and the specific surface area decreased with temperature. Moreover, the effect of the doping with Er 3+ and Eu 3+ was studied and a clear inhibition of the crystal growth and the sintering process was detected (by transmission electron and atomic force microscopy) when the doped films are compared with the undoped ones. Finally, Eu 3+ and Er 3+ f–f transitions were detected by PL measurements. - Highlights: • Eu and Er–TiO 2 mesoporous films were prepared by evaporation induced self-assembly. • Influence of humidity on porosity and photoluminescent properties has been tested. • Influence of calcination on structural and textural properties has been also studied. • f–f transitions indicate that the thin films are active photoluminescent materials

Relation between crystallinity and chemical nature of surface on wettability: A study on pulsed laser deposited TiO2 thin films

International Nuclear Information System (INIS)

Shirolkar, Mandar M.; Phase, Deodatta; Sathe, Vasant; Choudhary, Ram Janay; Rodriguez-Carvajal, J.; Kulkarni, Sulabha K.

2011-01-01

Pure titania (TiO 2 ) polycrystalline thin films in rutile, anatase and mixed phase have been grown on amorphous glass substrates by pulsed laser deposition method at various oxygen gas pressure. Wettability investigations have been carried out on these films. Consistent with our previous report [J. Phys. D: Appl. Phys. 41, 155308 (2008)] it has been observed that for nearly same surface roughness large contact angle or superhydrophobicity is present when sample has a pure single phase and lower contact angle or hydrophobicity when mixed phases were present. Structural characterizations suggest that in addition to roughness, pure phase film surface associated with hydrophobic sites and mixed phase film surface show association of both hydrophobic and hydrophilic sites, which might be inducing specific wetting character. UV treatment induces superhydrophilicity in the films. It was observed that UV irradiation causes nonequilibrium state on the TiO 2 surface, leading to changes in the electron density, which in turn produces decrement in the crystallinity and lattice expansion. Reversible changes in the wetting state on the pure phase surfaces were observed to be faster than those on the mixed phase surfaces. We tried to establish the possible relation between crystalline phases, chemical nature of surface on reversible wettability besides the main governing parameter viz. surface roughness.

Effect of Sr doping on LaTiO3 thin films

International Nuclear Information System (INIS)

Vilquin, B.; Kanki, T.; Yanagida, T.; Tanaka, H.; Kawai, T.

2005-01-01

We report on the electric properties of La 1-x Sr x TiO 3 (0 ≤ x ≤ 0.5) thin films fabricated by pulsed laser deposition method. Crystallographic measurement of the thin films showed the epitaxial c-axis perovskite structure. The electric property of LaTiO 3 thin film, which is a typical Mott insulative material in bulk, showed insulative behaviour, while the Sr-doped films showed metallic conduction suffering electron-electron scattering. Below x = 0.1, the major carrier type was identified to be hole, and switched to electron with further increasing Sr-doping above x = 0.15. In fact, the switching from p-type to n-type for La 1-x Sr x TiO 3 thin films is first demonstrated in this study. The transition suggests that effective Coulomb gap vanishes due to over-additional Sr doping

Characteristics of TiO_2/ZnO bilayer film towards pH sensitivity prepared by different spin coating deposition process

International Nuclear Information System (INIS)

Rahman, Rohanieza Abdul; Zulkefle, Muhammad Al Hadi; Abdullah, Wan Fazlida Hanim; Rusop, M.; Herman, Sukreen Hana

2016-01-01

In this study, titanium dioxide (TiO_2) and zinc oxide (ZnO) bilayer film for pH sensing application will be presented. TiO_2/ZnO bilayer film with different speed of spin-coating process was deposited on Indium Tin Oxide (ITO), prepared by sol-gel method. This fabricated bilayer film was used as sensing membrane for Extended Gate Field-Effect Transistor (EGFET) for pH sensing application. Experimental results indicated that the sensor is able to detect the sensitivity towards pH buffer solution. In order to obtained the result, sensitivity measurement was done by using the EGFET setup equipment with constant-current (100 µA) and constant-voltage (0.3 V) biasing interfacing circuit. TiO_2/ZnO bilayer film which the working electrode, act as the pH-sensitive membrane was connected to a commercial metal-oxide semiconductor FET (MOSFET). This MOSFET then was connected to the interfacing circuit. The sensitivity of the TiO2 thin film towards pH buffer solution was measured by dipping the sensing membrane in pH4, pH7 and pH10 buffer solution. These thin films were characterized by using Field Emission Scanning Electron Microscope (FESEM) to obtain the surface morphology of the composite bilayer films. In addition, I-V measurement was done in order to determine the electrical properties of the bilayer films. According to the result obtained in this experiment, bilayer film that spin at 4000 rpm, gave highest sensitivity which is 52.1 mV/pH. Relating the I-V characteristic of the thin films and sensitivity, the sensing membrane with higher conductivity gave better sensitivity.

An efficient visible and UV-light-activated B–N-codoped TiO2 photocatalytic film for solar depollution prepared via a green method

International Nuclear Information System (INIS)

Xu Qingchi; Zhang Yan; He Ziming; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

2012-01-01

This work reports an efficient visible and UV-light-activated boron and nitrogen codoped TiO 2 porous film prepared via a “green” and direct coating approach. Such photocatalyst is highly promising for solar depollution application due to its efficient photocatalytic activities in both visible and UV spectrum. The preparation method avoids the use of organic solvents, which are usually more expensive and hazardous compared with water. Using stearic acid as the model organic pollutant, the visible-light photocatalytic activity of optimized porous B–N-codoped TiO 2 film (p-3B–N–TiO 2 ) is 3 times higher than that of porous N-doped TiO 2 (p-N–TiO 2 ) film, while its UV photocatalytic activity is almost double that of p-N–TiO 2 film and comparable to that of porous TiO 2 . The enhancement in photocatalytic activity is attributed to higher surface area due to the porous structure, improved visible-light absorption attributed to interstitially substituted boron atoms, and coexistence of boron and nitrogen dopants which may reduce Ti 3+ recombination centers.

Dye-Sensitized Solar Cells with Anatase TiO2 Nanorods Prepared by Hydrothermal Method

Directory of Open Access Journals (Sweden)

Ming-Jer Jeng

2013-01-01

Full Text Available The hydrothermal method provides an effective reaction environment for the synthesis of nanocrystalline materials with high purity and well-controlled crystallinity. In this work, we started with various sizes of commercial TiO2 powders and used the hydrothermal method to prepare TiO2 thin films. We found that the synthesized TiO2 nanorods were thin and long when smaller TiO2 particles were used, while larger TiO2 particles produced thicker and shorter nanorods. We also found that TiO2 films prepared by TiO2 nanorods exhibited larger surface roughness than those prepared by the commercial TiO2 particles. It was found that a pure anatase phase of TiO2 nanorods can be obtained from the hydrothermal method. The dye-sensitized solar cells fabricated with TiO2 nanorods exhibited a higher solar efficiency than those fabricated with commercial TiO2 nanoparticles directly. Further, triple-layer structures of TiO2 thin films with different particle sizes were investigated to improve the solar efficiency.

Electrical response of electron selective atomic layer deposited TiO2‑x heterocontacts on crystalline silicon substrates

Science.gov (United States)

Ahiboz, Doğuşcan; Nasser, Hisham; Aygün, Ezgi; Bek, Alpan; Turan, Raşit

2018-04-01

Integration of oxygen deficient sub-stoichiometric titanium dioxide (TiO2‑x) thin films as the electron transporting-hole blocking layer in solar cell designs are expected to reduce fabrication costs by eliminating high temperature processes while maintaining high conversion efficiencies. In this paper, we conducted a study to reveal the electrical properties of TiO2‑x thin films grown on crystalline silicon (c-Si) substrates by atomic layer deposition (ALD) technique. Effect of ALD substrate temperature, post deposition annealing, and doping type of the c-Si substrate on the interface states and TiO2‑x bulk properties were extracted by performing admittance (C-V, G-V) and current-voltage (J-V) measurements. Moreover, the asymmetry in C-V and J-V measurements between the p-n type and n-n TiO2‑x-c-Si heterojunction types were examined and the electron transport selectivity of TiO2‑x was revealed.

Preparation of TiO2/boron-doped diamond/Ta multilayer films and use as electrode materials for supercapacitors

Science.gov (United States)

Shi, Chao; Li, Hongji; Li, Cuiping; Li, Mingji; Qu, Changqing; Yang, Baohe

2015-12-01

We report nanostructured TiO2/boron-doped diamond (BDD)/Ta multilayer films and their electrochemical performances as supercapacitor electrodes. The BDD films were grown on Ta substrates using electron-assisted hot filament chemical vapor deposition. Ti metal layers were deposited on the BDD surfaces by radio frequency magnetron sputtering, and nanostructured TiO2/BDD/Ta thin films were prepared by electrochemical etching and thermal annealing. The successful formation of TiO2 and Ta layered nanostructures was demonstrated using scanning electron and transmission electron microscopies. The electrochemical responses of these electrodes were evaluated by examining their use as electrical double-layer capacitors, using cyclic voltammetry, and galvanostatic charge/discharge and impedance measurements. When the TiO2/BDD/Ta film was used as the working electrode with 0.1 M Na2SO4 as the electrolyte, the capacitor had a specific capacitance of 5.23 mF cm-2 at a scan rate of 5 mV s-1 for a B/C ratio of 0.1% w/w. Furthermore, the TiO2/BDD/Ta film had improved electrochemical stability, with a retention of 89.3% after 500 cycles. This electrochemical behavior is attributed to the quality of the BDD, the surface roughness and electrocatalytic activities of the TiO2 layer and Ta nanoporous structures, and the synergies between them. These results show that TiO2/BDD/Ta films are promising as capacitor electrodes for special applications.

Effect of Oxygen Partial Pressure on the Electrical and Optical Properties of DC Magnetron Sputtered Amorphous TiO2 Films

OpenAIRE

Chandra Sekhar, M.; Kondaiah, P.; Radha Krishna, B.; Uthanna, S.

2013-01-01

Titanium dioxide (TiO2) thin films were deposited on p-Si (100) and Corning glass substrates held at room temperature by DC magnetron sputtering at different oxygen partial pressures in the range 9 × 10−3–9 × 10−2 Pa. The influence of oxygen partial pressure on the structural, electrical, and optical properties of the deposited films was systematically studied. XPS studies confirmed that the film formed at an oxygen partial pressure of 6×10−2 Pa was nearly stoichiometric. TiO2 films formed at...

Plasmonic metamaterial-based chemical converted graphene/TiO2/Ag thin films by a simple spray pyrolysis technique

Science.gov (United States)

Kumar, Promod; Swart, H. C.

2018-04-01

Graphene based hybrid nanostructures have received special attention in both the scientific and technological development due to their unique physicochemical behavior, which make them attractive in various applications such as, batteries, supercapacitors, fuel cells, solar cells, photovoltaic devices and bio-sensors. In the present study, the role of plasmonic metamaterials in light trapping photovoltaics for inorganic semiconducting materials by a simple and low cost spray pyrolysis technique has been studied. The plasmonic metamaterials thin film has been fabricated by depositing chemically converted graphene (CCG) onto TiO2-Ag nanoparticles which has a low resistivity and a low electron-hole recombination probability. The localized surface plasmon resonance at the metal-dielectric interface for the Ag nanoparticles has been observed at 403 nm after depositing chemical converted graphene (CCG) on the TiO2-Ag thin film. The results suggest that the stacking order of the CCG/TiO2/Ag plasmonic metamaterials samples did not change the band gap of TiO2 while it changed the conductivity of the film. Thus the diffusion of the noble metals in the glass and TiO2 matrices based thin films can trap the light of a particular wavelength by mean of plasmonic resonance and may be useful for superior photovoltaic and optoelectronic applications.

A comparison of light-coupling into high and low index nanostructured photovoltaic thin films

Directory of Open Access Journals (Sweden)

T. Pfadler

2015-06-01

Full Text Available Periodically structured electrodes are typically introduced to thin-film photovoltaics for the purpose of light management. Highly effective light-trapping and optimal in-coupling of light is crucial to enhance the overall device performance in such thin-film systems. Here, wavelength-scale structures are transferred via direct laser interference patterning to electron-selective TiO2 electrodes. Two representative thin-film solar cell architectures are deposited on top: an organic solar cell featuring blended P3HT:PCBM as active material, and a hybrid solar cell with Sb2S3 as inorganic active material. A direct correlation in the asymmetry in total absorption enhancement and in structure-induced light in-coupling is spectroscopically observed for the two systems. The structuring is shown to be beneficial for the total absorption enhancement if a high n active material is deposited on TiO2, but detrimental for a low n material. The refractive indices of the employed materials are determined via spectroscopic ellipsometry. The study outlines that the macroscopic Fresnel equations can be used to investigate the spectroscopically observed asymmetry in light in-coupling at the nanostructured TiO2 active material interfaces by visualizing the difference in reflectivity caused by the asymmetry in refractive indices.

Synergistic effects for the TiO2/RuO2/Pt photodissociation of water

Energy Technology Data Exchange (ETDEWEB)

Blondel, G; Harriman, A; Williams, D

1983-07-01

Compressed discs of naked TiO2 or TiO2 coated with a thin film of a noble metal (e.g. Pt) do not photodissociate water upon illumination with UV light, but small amounts of H2 are generated if the TiO2 has been reduced in a stream of H2 at 600 C. Discs prepared from mixtures of TiO2/RuO2 facilitate the UV photodissociation of water into H2 and O2 although the yields are very low. When a thin (about 9 nm) film of Pt is applied to the TiO2/RuO2 discs, the yields of H2 and O2 observed upon irradiation with UV light are improved drastically. 25 references.

Electrodeposition of flake-like Cu_2O on vertically aligned two-dimensional TiO_2 nanosheet array films for enhanced photoelectrochemical properties

International Nuclear Information System (INIS)

Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi

2017-01-01

Highlights: • Flake-like Cu_2O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu_2O growth. • The Cu_2O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu_2O/TNS composite structure of single crystal TiO_2 nanosheet (TNS) arrays decorated with flake-like Cu_2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu_2O become agglomerating, and transform into dense Cu_2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu_2O and n-type TiO_2 heterojunctions combined with two-dimensional TiO_2 nanosheet with exposed highly reactive {001} facets.

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

International Nuclear Information System (INIS)

Hodroj, A.; Roussel, H.; Crisci, A.; Robaut, F.; Gottlieb, U.; Deschanvres, J.L.

2006-01-01

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

Hydrogenated TiO2 Thin Film for Accelerating Electron Transport in Highly Efficient Planar Perovskite Solar Cells.

Science.gov (United States)

Yao, Xin; Liang, Junhui; Li, Yuelong; Luo, Jingshan; Shi, Biao; Wei, Changchun; Zhang, Dekun; Li, Baozhang; Ding, Yi; Zhao, Ying; Zhang, Xiaodan

2017-10-01

Intensive studies on low-temperature deposited electron transport materials have been performed to improve the efficiency of n-i-p type planar perovskite solar cells to extend their application on plastic and multijunction device architectures. Here, a TiO 2 film with enhanced conductivity and tailored band edge is prepared by magnetron sputtering at room temperature by hydrogen doping (HTO), which accelerates the electron extraction from perovskite photoabsorber and reduces charge transfer resistance, resulting in an improved short circuit current density and fill factor. The HTO film with upward shifted Fermi level guarantees a smaller loss on V OC and facilitates the growth of high-quality absorber with much larger grains and more uniform size, leading to devices with negligible hysteresis. In comparison with the pristine TiO 2 prepared without hydrogen doping, the HTO-based device exhibits a substantial performance enhancement leading to an efficiency of 19.30% and more stabilized photovoltaic performance maintaining 93% of its initial value after 300 min continuous illumination in the glove box. These properties permit the room-temperature magnetron sputtered HTO film as a promising electron transport material for flexible and tandem perovskite solar cell in the future.

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.

Nano-crystalline thin and nano-particulate thick TiO2 layer: Cost effective sequential deposition and study on dye sensitized solar cell characteristics

International Nuclear Information System (INIS)

Das, P.; Sengupta, D.; Kasinadhuni, U.; Mondal, B.; Mukherjee, K.

2015-01-01

Highlights: • Thin TiO 2 layer is deposited on conducting substrate using sol–gel based dip coating. • TiO 2 nano-particles are synthesized using hydrothermal route. • Thick TiO 2 particulate layer is deposited on prepared thin layer. • Dye sensitized solar cells are made using thin and thick layer based photo-anode. • Introduction of thin layer in particulate photo-anode improves the cell efficiency. - Abstract: A compact thin TiO 2 passivation layer is introduced between the mesoporous TiO 2 nano-particulate layer and the conducting glass substrate to prepare photo-anode for dye-sensitized solar cell (DSSC). In order to understand the effect of passivation layer, other two DSSCs are also developed separately using TiO 2 nano-particulate and compact thin film based photo-anodes. Nano-particles are prepared using hydrothermal synthesis route and the compact passivation layer is prepared by simply dip coating the precursor sol prepared through wet chemical route. The TiO 2 compact layer and the nano-particles are characterised in terms of their micro-structural features and phase formation behavior. It is found that introduction of a compact TiO 2 layer in between the mesoporous TiO 2 nano-particulate layer and the conducting substrate improves the solar to electric conversion efficiency of the fabricated cell. The dense thin passivation layer is supposed to enhance the photo-excited electron transfer and prevent the recombination of photo-excited electrons

Optical properties of titanium di-oxide thin films prepared by dip coating method

Science.gov (United States)

Biswas, Sayari; Rahman, Kazi Hasibur; Kar, Asit Kumar

2018-05-01

Titanium dioxide (TiO2) thin films were prepared by sol-gel dip coating method on ITO coated glass substrate. The sol was synthesized by hydrothermal method at 90°C. The sol was then used to make TiO2 films by dip coating. After dip coating the rest of the sol was dried at 100°C to make TiO2 powder. Thin films were made by varying the number of dipping cycles and were annealed at 500°C. XRD study was carried out for powder samples that confirms the formation of anatase phase. Transmission spectra of thin films show sharp rise in the violet-ultraviolet transition region and a maximum transmittance of ˜60%. Band gap of the prepared films varies from 3.15 eV to 3.22 eV.

Low-temperature sputtering of crystalline TiO2 films

International Nuclear Information System (INIS)

Musil, J.; Herman, D.; Sicha, J.

2006-01-01

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 T surf necessary to form crystalline TiO 2 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 Ti 5 O 9 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 T surf using thermostrips pasted to the glass substrate. It was found that (1) T surf is considerably higher (approximately by 100 deg. C or more) than the substrate temperature T s measured by the thermocouple incorporated into the substrate holder and (2) T surf strongly depends on the substrate-to-target distance d s-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 TiO 2 films depends not only on T surf but also on the total pressure p T of sputtering gas (Ar+O 2 ), partial pressure of oxygen p O 2 , the film deposition rate a D , and the film thickness h (2) crystalline TiO 2 films with well developed anatase structure can be formed at T surf =160 deg. C and low values of a D ≅5 nm/min (3) the crystalline structure of TiO 2 film gradually changes from (i) anatase through (ii) anatase+rutile mixture, and (iii) pure rutile to x-ray amorphous structure at T surf =160 deg. C and p T =0.75 Pa when p O 2 decreases and a D increases above 5 nm/min, and (4) crystallinity of the TiO 2 films decreases with decreasing h and T surf . Interrelationships between the structure of TiO 2 film, its roughness, T surf , and a D are discussed in detail. Trends of next development are

Ion Beam Assisted Deposition of Thin Epitaxial GaN Films.

Science.gov (United States)

Rauschenbach, Bernd; Lotnyk, Andriy; Neumann, Lena; Poppitz, David; Gerlach, Jürgen W

2017-06-23

The assistance of thin film deposition with low-energy ion bombardment influences their final properties significantly. Especially, the application of so-called hyperthermal ions (energy GaN thin films on (0001)-oriented 6H-SiC substrates at 700 °C. The films are studied in situ by reflection high energy electron diffraction, ex situ by X-ray diffraction, scanning tunnelling microscopy, and high-resolution transmission electron microscopy. It is demonstrated that the film growth mode can be controlled by varying the ion to atom ratio, where 2D films are characterized by a smooth topography, a high crystalline quality, low biaxial stress, and low defect density. Typical structural defects in the GaN thin films were identified as basal plane stacking faults, low-angle grain boundaries forming between w-GaN and z-GaN and twin boundaries. The misfit strain between the GaN thin films and substrates is relieved by the generation of edge dislocations in the first and second monolayers of GaN thin films and of misfit interfacial dislocations. It can be demonstrated that the low-energy nitrogen ion assisted molecular beam epitaxy is a technique to produce thin GaN films of high crystalline quality.

Silver loaded WO3−x/TiO2 composite multifunctional thin films

International Nuclear Information System (INIS)

Dunnill, Charles W.; Noimark, Sacha; Parkin, Ivan P.

2012-01-01

Multifunctional WO 3−x –TiO 2 composite thin films have been prepared by sol–gel synthesis and shown to be good visible light photocatalysts whilst retaining a desirable underlying blue colouration. The WO 3−x –TiO 2 composite thin films were further enhanced using silver nanoparticles synthesised in-situ on the surface from the photo-degradation of silver nitrate solution. Thin films were characterised using X-ray diffraction, Raman, Scanning electron microscopy and UV–visible spectroscopy and shown to photo degrade stearic acid, using white light λ = 420–800 nm. - Highlights: ► WO 3−X TiO 2 composite thin films were synthesised by sol–gel methods. ► Blue tinted glass is desirable for the value added glass industry. ► Silver nanoparticle island formation enhances the activity of the films. ► Blue tinted “value added” coated glass is now possible.

TiO2 and SiC nanostructured films, organized CNT structures

Indian Academy of Sciences (India)

sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

Study of Optical Humidity Sensing Properties of Sol-Gel Processed TiO2 and MgO Films

Directory of Open Access Journals (Sweden)

B. C. Yadav

2007-04-01

Full Text Available Paper reports a comparative study of humidity sensing properties of TiO2 and MgO films fabricated by Sol-gel technique using optical method. One sensing element of the optical humidity sensor presented here consists of rutile structured two-layered TiO2 thin film deposited on the base of an isosceles glass prism. The other sensing element consists of a film of MgO deposited by same technique on base of the prism. Light from He-Ne laser enters prism from one of refracting faces of the prism and gets reflected from the glass-film interface, before emerging out from its other isosceles face. This emergent beam is allowed to pass through an optical fiber. Light coming out from the optical fiber is measured with an optical power meter. Variations in the intensity of light caused by changes in humidity lying in the range 5%RH to 95%RH have been recorded. MgO film shows better sensitivity than TiO2 film.

Hybrid thin films based on bilayer heterojunction of titania nanocrystals/polypyrrole/natural dyes (Kappaphycus alvarezii) materials

Science.gov (United States)

Ghazali, Salmah Mohd; Salleh, Hasiah; Dagang, Ahmad Nazri; Ghazali, Mohd Sabri Mohd; Ali, Nik Aziz Nik; Rashid, Norlaily Abdul; Kamarulzaman, Nurul Huda; Ahmad, Wan Almaz Dhafina Che Wan

2017-09-01

In this research, hybrid thin films which consist of a combination of organic red seaweed (RS) (Kappaphycus alvarezii) and polypyrrole (PPy) with inorganic titania nanocrystals (TiO2 NCs) materials were fabricated. These hybrid thin films were fabricated accordingly with bilayer heterojunction of ITO/TiO2 NCs/PPy/RS via electrochemical method using Electrochemical Impedance Spectroscopy (EIS). The effect of number of scans (thickness) of titania on optical and electrical properties of hybrid thin films were studied. TiO2 NCs function as an electron acceptor and electronic conductor. Meanwhile, PPy acts as holes conductor and RS dye acts as a photosensitizer enhances the optical and electrical properties of the thin films. The UV absorption spectrum of TiO2 NCs, PPy and RS are characterized by UV-Visible spectroscopy, while the functional group of RS was characterized by Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectra showed that TiO2 NCs, PPy and RS were absorbed over a wide range of light spectrum which were 200-300 nm, 300-900 nm and 250-900 nm; respectively. The FTIR spectra of the RS showed the presence of hydroxyl group which was responsible for a good sensitizer for these hybrid solar cells. The electrical conductivity of these hybrid thin films were measured by using four point probes. The electrical conductivity of ITO/ (1)TiO2 NCs/PPy/RS thin film under the radiation of 100 Wm-2 was 0.062 Scm-1, hence this hybrid thin films can be applied in solar cell application.

Surface Structure and Photocatalytic Activity of Nano-TiO2 Thin Film

Science.gov (United States)

Controlled titanium dioxide (TiO2) thin films were deposited on stainless steel surfaces using flame aerosol synthetic technique, which is a one-step coating process, that doesn’t require further calcination. Solid state characterization of the coatings was conducted by different...

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

International Nuclear Information System (INIS)

Villafuerte, Manuel; Juarez, Gabriel; Heluani, Silvia P. de; Comedi, David

2007-01-01

We have measured the current-voltage characteristics at room temperature of a nanocrystalline TiO 2 thin film fabricated by reactive RF-sputtering deposition and sandwiched between ITO (indium-tin-oxide)-buffered glass substrate and an indium top electrode. The I-V characteristics are ohmic for low voltages and become non-linear, hysteretic and asymmetric as the voltage is increased. The system is shown to be well represented by two distinct resistance states in the non-ohmic region. Current transient evolutions were also measured for constant voltage excitations. The resistance is stable in time for voltages in the ohmic regime. In contrast, for voltages in the non-ohmic regime, the resistance has a small variation for a short period of time (order of tens seconds) and then increases with time. For those transients, long characteristic times (on the order of tens of minutes up to hours) were found. The behavior of the system is discussed on the basis of experimental results reported in the literature for similar systems and existing models for electric-field induced resistive switching

Synthesis, Characterization and Sonocatalytic Activity of Co/N/Er3+ : Y3Al5O12 /TiO2 Film for the Degradation of Organic Dyes

Directory of Open Access Journals (Sweden)

Wang L.

2015-07-01

Full Text Available The sonocatalytic degradation of organic dyes (C.I. 50040, C.I. Reactive Red 1, C.I. Acid Orange 7 catalysed by Co/N/Er3+ : Y3Al5O12/TiO2 films was studied. For the preparation of Co/N/Er3+ : Y3Al5O12/TiO2 films, the sol-gel coating process was used. The phase composition, morphology, precursor at different temperatures and emitting light properties of the calcined powders were analysed by X-ray diffraction (XRD, absorption spectra and upconversion emission spectra. The X-ray diffraction of powder samples of Co/N/Er3+ : Y3Al5O12/TiO2 took on anatase mine peaks and upconversion luminous agent, respectively. Analysis of absorption spectra of amorphous Co/N/Er3+ : Y3Al5O12/TiO2 showed that doping N stretching vibration peak of water or hydroxyl adsorption, Co2+ ion had very strong absorption in 1.0–1.7 μm wavelength range, the transition luminescence of Er3+ ions was just on Co2+ ions absorption band. The emission spectrum indicated that Co/N/Er3+ : Y3Al5O12/TiO2 could launch green 500–560 nm and red 650–700 nm, 525, 550 and 660 nm peaks corresponding to 2H11/2, 4S3/2 → 4I15/2 and 4H9/2 → 4I15/2 transition of Er3+. Doping Co and N enhanced the upconversion luminescence and absorption effect. Sonocatalytic degradation effect of organic dyes loading Co/N/Er3+ : Y3Al5O12/TiO2 was better when ultrasonic intensity was equal to 15 W cm–2. The degradation ratios of aqueous solutions of these three kinds of organic dyes by ultrasonic irradiation were obviously lower than by ultrasonic irradiation together with Co/N/Er3+ : Y3Al5O12/TiO2 films in the same conditions. Degradation kinetics of organic dyes by ultrasonic irradiation and by ultrasonic irradiation cooperating with Co/N/Er3+ : Y3Al5O12/TiO2 films followed the first-order reaction.

Photoluminescence study of trap-state defect on TiO2 thin films at different substrate temperature via RF magnetron sputtering

Science.gov (United States)

Abdullah, S. A.; Sahdan, M. Z.; Nafarizal, N.; Saim, H.; Bakri, A. S.; Cik Rohaida, C. H.; Adriyanto, F.; Sari, Y.

2018-04-01

This paper highlights the defect levels using photoluminescence spectroscopy of TiO2 thin films. The TiO2 were deposited by Magnetron Sputtering system with 200, 300, 400, and 500 °C substrate temperature on microscope glass substrate. The PL result shows profound effect of various substrate temperatures to defect levels of oxygen vacancies and Ti3+ at titanium interstitial site. Increasing temperature would minimize the oxygen vacancy defect, however Ti3+ shows otherwise. Green region of PL consist of trapped hole for oxygen vacancy, while red region of PL is trapped electron associated to structural defect Ti3+. Green PL is dominant peak at temperature 200 °C, indicating that oxygen vacancy is the main defect at this temperature. However, PL peak shows slightly same value for others samples indicating that the temperature did not give high influence to other level of defect after 200 °C.

Adsorption Equilibrium and Kinetics of Gardenia Blue on TiO2 Photoelectrode for Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Tae-Young Kim

2014-01-01

Full Text Available Nanostructured porous TiO2 paste was deposited on the FTO conductive glass using squeeze printing technique in order to obtain a TiO2 thin film with a thickness of 10 μm and an area of 4 cm2. Gardenia blue (GB extracted from Gardenia jasminode Ellis was employed as the natural dye for a dye-sensitized solar cell (DSSC. Adsorption studies indicated that the maximum adsorption capacity of GB on the surface of TiO2 thin film was approximately 417 mg GB/g TiO2 photoelectrode. The commercial and natural dyes, N-719 and GB, respectively, were employed to measure the adsorption kinetic data, which were analyzed by pseudo-first-order and pseudo-second-order models. The energy conversion efficiency of the TiO2 electrode with successive adsorptions of GB dye was about 0.2%.

Bandtail characteristics in InN thin films

International Nuclear Information System (INIS)

Shen, W.Z.; Jiang, L.F.; Yang, H.F.; Meng, F.Y.; Ogawa, H.; Guo, Q.X.

2002-01-01

The Urbach bandtail characteristics in InN thin films grown by radio-frequency magnetron sputtering on sapphire (0001) substrates have been investigated both theoretically and experimentally. The bandtail parameter in InN thin films has been obtained by temperature-dependent transmission spectra, with the aid of a detailed calculation of the transmission profile. A bandtail model based on the calculation of density of occupied states and the carrier-phonon interaction has been employed to analyze the temperature-dependent bandtail characteristics. The bandtail parameter is in the range of 90-120 meV in the InN thin film. It is found that the carrier-phonon interaction in InN is weak and the structural disorder contribution (∼90 meV) dominates over the interactive terms. The high structural disorder in InN thin films may relate to the high nonradiative recombination centers

EGFET pH Sensor Performance Dependence on Sputtered TiO2 Sensing Membrane Deposition Temperature

Directory of Open Access Journals (Sweden)

Khairul Aimi Yusof

2016-01-01

Full Text Available Titanium dioxide (TiO2 thin films were sputtered by radio frequency (RF magnetron sputtering method and have been employed as the sensing membrane of an extended gate field effect transistor (EGFET for pH sensing detection application. The TiO2 thin films were deposited onto indium tin oxide (ITO coated glass substrates at room temperature and 200°C, respectively. The effect of deposition temperature on thin film properties and pH detection application was analyzed. The TiO2 samples used as the sensing membrane for EGFET pH-sensor and the current-voltage (I-V, hysteresis, and drift characteristics were examined. The sensitivity of TiO2 EGFET sensing membrane was obtained from the transfer characteristic (I-V curves for different substrate heating temperatures. TiO2 thin film sputtered at room temperature achieved higher sensitivity of 59.89 mV/pH compared to the one deposited at 200°C indicating lower sensitivity of 37.60 mV/pH. Moreover the hysteresis and the drift of TiO2 thin film deposited at room temperature showed lower values compared to the one at 200°C. We have also tested the effect of operating temperature on the performance of the EGFET pH-sensing and found that the temperature effect was very minimal.

Low-temperature atomic layer deposition of TiO2 thin layers for the processing of memristive devices

International Nuclear Information System (INIS)

Porro, Samuele; Conti, Daniele; Guastella, Salvatore; Ricciardi, Carlo; Jasmin, Alladin; Pirri, Candido F.; Bejtka, Katarzyna; Perrone, Denis; Chiolerio, Alessandro

2016-01-01

Atomic layer deposition (ALD) represents one of the most fundamental techniques capable of satisfying the strict technological requirements imposed by the rapidly evolving electronic components industry. The actual scaling trend is rapidly leading to the fabrication of nanoscaled devices able to overcome limits of the present microelectronic technology, of which the memristor is one of the principal candidates. Since their development in 2008, TiO 2 thin film memristors have been identified as the future technology for resistive random access memories because of their numerous advantages in producing dense, low power-consuming, three-dimensional memory stacks. The typical features of ALD, such as self-limiting and conformal deposition without line-of-sight requirements, are strong assets for fabricating these nanosized devices. This work focuses on the realization of memristors based on low-temperature ALD TiO 2 thin films. In this process, the oxide layer was directly grown on a polymeric photoresist, thus simplifying the fabrication procedure with a direct liftoff patterning instead of a complex dry etching process. The TiO 2 thin films deposited in a temperature range of 120–230 °C were characterized via Raman spectroscopy and x-ray photoelectron spectroscopy, and electrical current–voltage measurements taken in voltage sweep mode were employed to confirm the existence of resistive switching behaviors typical of memristors. These measurements showed that these low-temperature devices exhibit an ON/OFF ratio comparable to that of a high-temperature memristor, thus exhibiting similar performances with respect to memory applications

Production and Characterization of (004) Oriented Single Anatase TiO2 Films

Science.gov (United States)

Atay, Ferhunde; Akyuz, Idris; Cergel, Muge Soyleyici; Erdogan, Banu

2018-02-01

Highly (004) oriented anatase TiO2 films have been successfully obtained by an inexpensive ultrasonic spray pyrolysis technique at low substrate temperatures and without additional annealing. X-ray diffraction analysis, ultraviolet-visible spectroscopy and field emission scanning electron microscopy were used to analyze the structural, optical and surface properties of the films. By using the less reported TiCl4 solution, the optical band gap values falling into the visible region (between 2.70 eV and 2.92 eV) have been obtained for all films. Spectroscopic ellipsometry technique has been used to determine the dispersive refractive index and extinction coefficient of TiO2 films. Possible electrical conduction mechanisms in TiO2 films have been examined using temperature dependent conductivity measurements in the temperature range of 78-300 K. At room temperature, electrical resistivity values of TiO2 films change between 1.68 × 104 Ω cm and 5.88 × 104 Ω cm. Considering the analyzed parameters with respect to substrate temperature, this work refers to the properties of anatase TiO2 films that are strongly correlated to the growth direction, namely (004). As a result, (004) oriented anatase TiO2 films with appropriate optical band gap values are promising materials for technological applications, especially for photocatalysts.