Preparation of Nanometer-structured TiO2 Thin Films by-Sol-Gel Method

The transparent anatse TiO2 nanometer thin films were prepared by the sol-gel method on soda-line glass,X-ray diffraction,thermal analysis and UV-visible spectrophotometer were used to analyze the formation of the phases,Only increasing the heat-treatment time,the average graing size has no obvious change,The mechanism of grain growth in TiO2 thin film is probably as follows:the grain of coating will become grain core later;TiO2 sol constantly deposited on the surface of TiO2 grain and formed membrance with increasing of coating cylce time ;TiO2 grain in the film grow steadily.     

Preparation of TiO_2 Thin Film and Its Antibacterial Activity

1　IntroductionInrecentyears ,theuseofinorganicantimicrobialagentshasattractedinterestforthecontrolofmicrobes[1-3 ] .Thekeyadvantagesofinorganicantimicro bialagentsareimprovedsafetyandstability ,ascomparedwithorganicantimicrobialagents .Atpresent,mostanti…     

Preparation and Properties of Dip-coated CeO2-TiO2 Thin Golden Glass Film

The golden and ultraviolet-absorbed CeO2-TiO2 film was prepared on soda-lime glass substrate with the thickness of 2 mm via the sol-gel method. The transmission spectra in range of 200 nm-800 nm were measured, and the crystallization, the abrasion and acid resistance were also investigated. The appropriate sol contents and heat-treatment schedule were determined. The results indicate that the appropriate molar ratio of Ce/Ti was 3：5 to 5：6. The ultraviolet-absorbance ability increased with the increase of the Ce/Ti molar ratio, but when the Ce/Ti molar ratio was higher than 1.5, the homogeneity of the film was deteriorated. With the increase of heat-treatment temperature, the main wavelengths of the color of the coated glasses were equal, but the color＇ s saturation decreased; the transmission peaks were the same, while the intensity of the peaks decreased. The roughness, abrasion and acid resistance of the film were also enhanced at the same time. The appropriate heat- treatment temperature may be 340℃.     

Preparation of TiO<Subscript>2</Subscript> thin film by the LPD method on functionalized organic self-assembled monolayers

In this paper, uniform titania (TiO₂) films have been formed at 50° on silanol SAMs by the liquid-phase deposition (LPD) method at a temperature below 100°C. OTS (Octadecyltrichloro-Silane) self-assembled monolayers (SAMs) on glass wafers were used as substrates for the deposition of titanium dioxide thin films. This functionalized organic surface has shown to be effective for promoting the growth of films from titanic aqueous solutions by the LPD method at a low temperature below 100°C. The crystal phase composition, microstructure and topography of the as-prepared films were characterized by various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that the as-prepared thin films are purely crystallized anatase TiO₂ constituted by nanorods after being annealed at 500°. The pH values, concentration of reactants, and deposition temperatures play important roles in the growth of TiO₂ thin films. Support by the National Natural Science Foundation of China (Grant No. 50672055) and National Key Technology R&D Program (Grant No. 2006BAF02A28)     

Effects of Nitrogen Doping on Microstructure and Photocatalytic Activity of Nanocrystalline TiO2 Powders

Nitrogen-doped TiO2 nanocrystalline powders were prepared by hydrolysis of tetrachloride titanium （TiCl4） in a mixed solution of ethanol and ammonium nitrate （NH4NO3） at ambient temperature and atmosphere followed by calcination at 400 ℃ for 2 h in air. FTIR spectra demonstrate that amine group in original gel is eliminated by calcination, and the TiO2 powder is liable to absorb water onto its surface and into its capillary pore. XRD and SEM results show that the average size of nanocrystalline TiO2 particles is no more than 60 nm and with increasing the calcination temperature, the size of particles increases. XPS studies indicate the nitrogen atom enters into the TiO2 lattice and occupies the position of oxygen atom. The nitrogen doping not only depresses the grain growth of TiO2 particles, but also reduces the phase transformation temperature of anatase to futile. The photocatalytic activity of the nitrogen-doped TiO2 powders has been evaluated by experiments of photocatalytic degradation aqueous methylene blue.     

Antibacterial properties of TiO<Subscript>2</Subscript> ceramic pellets prepared using nano TiO<Subscript>2</Subscript> powder

Titanium dioxide (TiO₂) porous ceramic pellets with three dimension nano-structure were prepared using nano TiO₂ powder. The TiO₂ porous ceramic pellets were composed of TiO₂ nanoparticles with 14–16 nm in diameter and had porosity of 74.85%. The mean pore size of the TiO₂ porous ceramic pellets was 20.73 nm and the main pore size ranged from 3 to 16 nm. The mass loss of the TiO₂ ceramic pellets was less than 5% after 20 d immersion in water. The antibacterial properties of the TiO₂ pellets were studied. The sterilization rate of Colibacillus (hospital polluted water with bacterium) can reach 99% after 3 h photocatalytic process and these TiO₂ pellets are easy to be re-activated and cyclically be used. The shaping mechanism and photocatalysis sterilization mechanism of the TiO₂ pellets were discussed. Funded by the Applied Basis Research from Sichuan Province, the Research of Photo Purification to Environment with Nano TiO₂ (No. 05YJ029-010)     

Preparation and Properties of IrO2 Thin Films Grown by Pulsed Laser Deposition Technique

Highly conductive IrO2 thin films were prepared on Si （100） substrates by means of pulsed laser deposition technique from an iridium metal target in an oxygen ambient atmosphere. Emphasis was put on the effect of oxygen pressure and substrate temperature on the structure, morphology and resistivity of IrO2 films. It was found that the above properties were strongly dependent on the oxygen pressure and substrate temperature. At 20 Pa oxygen ambient pressure, pure polycrystalline IrO2 thin films were obtained at substrate temperature in the 300-500℃ range with the preferential growth orientation of IrO2 films changed with the substrate temperature. IrO2 films exhibited a uniform and densely packed granular morphology with an average feature size increasing with the substrate temperature. The room-temperature resistivity variations of IrO2 films correlated well with the corresponding film morphology changes. IrO2 films with the minimum resistivity of （42 ±6）μΩ·cm was obtained at 500℃.     

Facile synthesis of nanocrystalline Cr<Subscript>2</Subscript>O<Subscript>3</Subscript> thin film

A novel and facile synthesis route for the manufacture of transparent and uniform self-assembled nanocrystalline Cr2O3 (nc-Cr2O3) thin films with different morphology was reported, utilizing chromium nitrate as the inorganic source and triblock copolymer F127 as the morphology-directing agent by the evaporation-induced assembly (EIA) method. X-ray powder diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), N2-sorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the as-prepared nc-Cr2O3 thin films. The Cr2O3 thin film with different morphology was obtained by changing the relative humidity. The possible formation mechanism of the nc-Cr2O3 thin films with different morphologies was discussed.     

Ferroelectric properties of Bi<Subscript>4</Subscript>Zr<Subscript>0.5</Subscript>Ti<Subscript>2.5</Subscript>O<Subscript>12</Subscript> thin films prepared on LaNiO<Subscript>3</Subscript> bottom electrode by sol-gel method

The Bi4Zr0.5Ti2.5O12 (BZT) thin films were fabricated on the LaNiO3 bottom electrode using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction, AFM and SEM. The results show that the films have a perovskite phase and dense microstructure. The 2Pr and 2Vc of the Pt/BZT/LaNiO3 capacitor are 28.2 μC/cm2 and 14.7 V respectively at an applied voltage of 25 V. After the switching of 1×1010 cycles, the Pr value decreases to 87% of its pre-fatigue values. The dielectric constant (ε) and the dissipation factor (tanδ) of the BZT thin films are about 204 and 0.029 at 1 kHz, respectively. The films show good insulating behavior according to the test of leakage current. The clockwise C-V hysteresis curve observed shows that the Pt/BZT/LaNiO3 structure has a memory effect because of the BZT film's ferroelectric polarization.     

Preparation and enhanced daylight-induced photo-catalytic activity of transparent C-Doped TiO<Subscript>2</Subscript> thin films

The transparent C-doped TiO₂ nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photo-catalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO₂ films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Photocatalytic activities of amorphous TiO<Subscript>2</Subscript>-Cr thin films prepared by magnetron sputtering

Chrome-doped titanium oxide films were prepared by reactive magnetron sputtering method. The films deposited on glass slides at room temperature were investigated by atom force microscope, X-ray diffractometer, X-ray photoelectron spectroscopy, UV-Vis spectrophotometer, the photoluminescence （PL） and ellipse polarization apparatus. The results indicate that TiO2-Cr film exists in the form of amorphous. The prepared films possess a band gap of less than 3.20 eV, and a new absorption peak. The films, irradiated for 5 h under UV light, exhibit excellent photocatalytic activities with the optimum decomposition rate at 98.5% for methylene blue. Consequently, the thickness threshold on these films is 114 nm, at which the rate of photodegradation is 95% in 5 h. When the thickness is over 114 nm, the rate of photodegradation becomes stable. This result is completely different from that of crystalloid TiO2 thin film.     

Bactericidal and Photocatalytie Activity of Fe^3＋-TiO2 Thin Films Prepared by the Sol-gel Method

Pure TiO2 thin films and iron doped TiO2 thin films on glass substrate were prepared by sol-gel method, and characterized by X-ray diffractometer （XRD）, thermo-gravimetric analysis （TG-DSC）, high resolution transmission electron microscope （HRTEM）, scanning electron microscope （SEM） and UV-Vis spectroscopy, respectively. The experimental results show that the pure TiO2 thin films and iron doped TiO2 thin films can destroy most of the escherichia coli and bacillus subtillis under the irradiation of 365 nm UV-light. However, the iron doped TiO2 thin film is a better photocatalyst than pure TiO2 thin film. The ultrastructural studies provide direct evidences for understanding the bactericidal mechanism of the TiO2 photocatalyst.     

Preparation and characterization of nanocomposite MgFe<Subscript>2</Subscript>O<Subscript>4</Subscript>/SiO<Subscript>2</Subscript>

Nanocomposites MgFe₂O₄/SiO₂ were successfully synthesized by the sol-gel method in the presence of N, N-dimethylformamide (DMF). The formation of pure MgFe₂O₄ was confirmed by powder X-ray diffraction (XRD) and electron diffraction. The structural evolution of MgFe₂O₄ nanocrystals was followed by powder X-ray diffraction and IR absorption spectroscopy. The formation of spinel structure of MgFe₂O₄ started at 800 °C, and completed at 900 °C. The transmission electron microscopy (TEM) measurements suggest that the particle sizes increase with the increasing annealing temperature, and the mean particle sizes of the spherical samples annealed at 800 °C, 900 °C and 1 050 °C are ca. 3 nm, 8 nm and 11 nm, respectively. Magnetization measurements at room temperature and 78 K indicate superparamagnetic nature of these MgFe₂O₄ nanocrystals. Funded by the National Natural Science Foundation of China(No. 30771676), the Natural Science Foundation of Jiangsu Province (No. BK20081842), and the Foundation of Nanjing Bureau of Personal for the Returned Overseas Chinese Excellent Scholars     

Crystallization and Electrical Properties of （Ba0.4Pb0.3）Sr0.3TiO3 Thin Film by Pulsed Laser Deposition

（Ba0.4Pb0.3）Sr0.3TiO3 thin films were fabricated via pulsed laser deposition （PLD） technique on Pt/TiO2/SiO2/Si substrate. The crystallization of the films was characterized by XRD and FSEM, and the experimental results suggested deposition parameters, especially the deposition temperature was the key factor in forming the perovskite structure. The dielectric properties of the film deposited with optimized parameters were studied by an Agilent 4294A impedance analyzer at 1 MHz. The dielectric constant was 772, and the loss tangent was 0.006. In addition, the well-shaped hysteresis loop also showed that the film had a well performance in ferroelectric. The saturated polarization P, remnant polarization Pr and coercive field E were about 4.6 μC/cm2, 2.5 μC/cm2 and 23 kV/cm （the coercive voltage is 0.7 V）, respectively. It is suggested the film should be a promising candidate for microwave applications and nonvolatile ferroelectric random access memories （NvFeRAMs）.     

Preparation and characterization of SrTiO<Subscript>3</Subscript> thin film on functional organic self-assembled monolayers

SrTiO₃ thin film was successfully prepared on the functionalized organic self-assembled monolayers (SAMs) by the Liquid Phase Deposition (LPD) method. The as-prepared samples were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscopy (SEM) and metallographic microscope. Measurement of contact angle showed that the hydrophobe substrate was changed into hydrophile by UV irradiation. AFM photographs of octadecyl-trichloro-silane self-assembled monolayer (OTS-SAM) surface approved that UV irradiation did change the morphology of OTS monolayer and provided evidence for the conversion of hydrophilic characteristic. Photographs of Metallographic Microscope showed that OTS-SAM had an active effect on the deposition of SrTiO₃ thin film. XRD and SEM indicated that the thin film was of pure cubic phase SrTiO₃ and composed of nanosized grains with a size in the range of 100–500 nm. The formation mechanism of the SrTiO₃ film was proposed.     

Influence of rare earth co-dopant on the photocatalytic property of TiO<Subscript>2</Subscript> nano-particles

A series of nanometer TiO2 photocatalysts co-doped respectively with rare earth Er3+-Ce3+ and La3+-Fe3+ were prepared by sol-gel method,and the photocatalytic activity under ultra-violet light was evaluated by photocatalytic degradation of methyl blue.The crystallographic forms,particles size,and morphology were characterized by XRD and TEM.The results showed that the optimum heat temperature of co-doped TiO2 was 550 ℃,and the co-doped TiO2 kept anatase.The anatase crystal had the average size of 20 nm.The ...     

Preparation and ferroelectric properties of Bi<Subscript>3.4</Subscript>Ce<Subscript>0.6</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films grown by sol-gel method

We have investigated the preparation and properties of Bi_3.4Ce_0.6Ti₃O₁₂ thin films. The Bi_3.4Ce_0.6Ti₃O₁₂ thin films were fabricated on the Pt/Ti/SiO₂/Si substrates using sol-gel method. The structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The thin films showed a perovskite phase and dense microstructure. The dielectric constant and the dissipation factor of the Bi_3.4Ce_0.6Ti₃O₁₂ thin films were about 172 and 0.031 at 1 kHz, respectively. The 2P _r and 2E _c of the Bi_3.4Ce_0.6Ti₃O₁₂ thin films were 67.1 μC/cm² and 299.7 kV/cm, respectively, under an applied field of 600 kV/cm. The Bi_3.4Ce_0.6Ti₃O₁₂ film did not show fatigue up to 4.46×10⁹ switching cycles at a frequency of 1 MHz, and showed good insulating behavior according to the test of leakage current. Supported by the Natural Science Foundation of Hubei Province (Grants No. 2004ABA082)     

Preparation of nano-TiO2 by liquid hydrolysis and characterization of its antibacterial activity

The nano-TiO2 particles were prepared by liquid hydrolysis method and characterized using XRD. Its antibacterial activity against two representative bacterial, Escherichia coli and Staphylococcus aureus, was also studied. The experimental results showed that the nano-TiO2 calcinated at 600-700 ℃ contained the obvious anatase phase and exerted excellent antibacterial activity. The feature of antibacterial activity of nanoTiO2 was non-strains specificity and exerted best antibacterial activity at concentration of 0.8 g/L.     

FeS<Subscript>2</Subscript> (pyrite) electrodeposition thin films and study of growth mechanism

With the development of semiconductor solar cells, much attention has been focused on the low-cost, high-performance photovoltaic materials for solar cell fabrications. Sul-fide compounds[1,2], due to their desirable optical properties, were widely used in pre-paring solar cells. Although the Cd-based II-VI compounds solar cell, such as CdS, CdTe, etc.[3,4], processes a higher conversion efficiency than the sulfide-based solar cell does. The iron pyrite (FeS2) characteristic of suitable ba…     

UV-vis and photoluminescent spectra of TiO<Subscript>2</Subscript> films

TiO₂ fims have been deposited on glass substrates using DC reactive magnetron sputtering at different oxygen partial pressures from 0. 10 Pa.to 0.65 Pa. The transmittance (UV-vis) and photoluminescence (PL) spectra of the films were recorded. The results of the UV-vis spectra show that the deposition rate of the films decreased at oxygen partial pressure P(O₂)≥0.15 Pa, the band gap increased from 3.48 eV to 3.68eV for direct transition and from 3.27 eV to 3.34 eV for indirect transition with increasing the oxygen partial pressure. The PL spectra show convincingly that the transition for films was indirect, and there were some oxygen defect energy levels at the band gap of the films. With increasing the O₂ partial pressure, the defect energy levels decreased. For the films sputtered at 0.35 and 0.65 Pa there were two defect energy levels at 2.63 eV and 2.41 eV, corresponding to 0.72 eV and 0.94 eV below the conduction band for a band gap of 3.35 eV, respectively. For the films sputtered at 0.10 Pa and 0.15 Pa, there was an energy band formed between 3.12 eV and 2.06 eV, corresponding to 0.23 eV and 1.29 eV below the conduction band. ZHAO Qing-nan : Born in 1963 Funded by Natural Science Foundation of Hubei Province, China.