Effect of Substrate Sodium Content on Crystallization and Photocatalytic Activity of TiO2 Films Prepared by DC Magnetron Sputtering (original) (raw)
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Photocatalytic TiO2 thin film deposited onto glass by DC magnetron sputtering
Thin Solid Films, 2001
A high performance photocatalytic TiO thin film was successfully obtained by reactive DC magnetron sputtering. The film was 2 deposited onto SiO-coated glass at a substrate temperature of 220ЊC using a titanium metal target in O 100% atmosphere. The 2 2 film showed good uniformity of thickness in a large area with the optical transmittance of ; 80% in the visible region. The Ž. decomposition ability of acetaldehyde CH CHO of the film under UV irradiation was almost the same as that of the 3 sol᎐gel-derived TiO thin film but the sputtered film showed a much higher mechanical durability. The characterization of the 2 films was carried out using XRD, SEM, AFM, XPS and SIMS, and the electronic structures of the films were calculated using a first-principle calculation method based on the density functional theory. It was found that the amount of incorporated 18 O into the film was larger for the films with lower photocatalytic activity when the films were annealed in 18 O rN atmosphere. This 2 2 result indicates that the amount of oxygen vacancies, which were occupied by incorporated 18 O, was larger for the films with lower photocatalytic activity. Furthermore, the introduction of structural defects associated with oxygen vacancies was found to create some energy levels around the mid-gap, indicating that they could work as recombination centers of photo-induced holes and electrons, causing the decrease in photocatalytic activity. Therefore, the decrease in the structural defects associated with oxygen vacancies is important for improving the photocatalytic activity of the films.
Photocatalytic activity of dc magnetron sputter deposited amorphous TiO2 thin films
Applied Surface Science, 2007
For photocatalytic thin film applications TiO 2 is one of the most important materials. The most studied TiO 2 crystal phase is anatase, though also rutile and brookite show good photoactivity. Usually anatase or a mixture of rutile and anatase is applied for powder or thin film catalysts. It has been claimed that amorphous films do not exhibit any or only a very low photocatalytic activity.
Reactive sputtering deposition of photocatalytic TiO 2 thin films on glass substrates
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2007
Titania polycrystalline thin films with high photocatalytic activity were produced by dc reactive magnetron sputtering. X-ray diffraction experiments revealed that the as-deposited films are amorphous and thus unable to deliver an optimum photocatalytic efficiency. By annealing the deposited coatings for 2 h at 500 • C a competitive crystallographic phase growth of anatase and rutile was observed. The anatase titania developed a very high photocatalytic activity. When immersed in a rhodamine B solution and irradiated with ultra-violet light for different periods of time, one could monitor the degradation rate of the dye concentration with time from the decay of its absorption spectra. Several deposition parameters dictate the optimum performance of the titania coatings, such as their relative oxygen and argon partial pressure, cathode current, bias voltage, external magnetic field and post-annealing temperature.
Thin Solid Films, 2006
TiO 2 thin films of 200 -300 nm thickness were deposited by d.c. magnetron sputtering onto glass substrates from a semiconducting TiO 2Àx target in pure Ar using pressures between 0.1 and 1.0 Pa. The obtained TiO 2 coatings are transparent and have refractive indices between 2.5 and 1.9. Post deposition heat treatment at different temperatures was performed to achieve crystallization of anatase TiO 2 . The as-deposited and heat treated films were examined with UV -VIS (transmission), SEM and XRD to investigate the influence of the argon pressure during deposition on the structural development during heat treatment. Additionally, the photocatalytic activity of the films was tested by measuring the decomposition rate of ethanol in a controlled gas atmosphere simulating air, and was related to their respective microstructures. D
Procedia Engineering, 2012
TiO 2 thin films were deposited by DC reactive magnetron sputtering technique on silicon wafer and glass slide at sputtering power of 210 W and 230 W. A pure metallic titanium target was sputtered in a mixture of argon and oxygen gases. The distance of Ti-target to substrate holder (d s-t) was 120 mm. The films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The photocatalytic activity was evaluated by the measurement of the decomposition of methylene blue after UV irradiation. It was found that the crystalline structure of TiO 2 thin films strongly depended on the sputtering power. The mixed phase of anatas/rutile TiO 2 thin films were successfully obtained with the sputtering power of 230 W. While anatase TiO 2 thin films were obtained with sputtering power of 210 W. The TiO 2 thin film with anatase structure exhibited the best photocatalytic activity.
Effect of substrate on surface morphology and photocatalysis of large-scale TiO2 films
Applied Surface Science, 2013
Nanostructured TiO 2 films were prepared on a variety of substrates, including acid frosted soda-lime glass, acid frosted soda-lime glass pre-coated with a SiO 2 barrier layer, commercial glazed ceramic tile and 6061 aluminum alloy. For each substrate, the phase and microstructure of the films were determined to be exclusively anatase. However, the growth of the TiO 2 crystallites, the film morphology and thickness varied substantially with substrate. Thermal stress, resulting from the difference in the coefficient of thermal expansion between the substrates and the films, contributed to the formation and propagation of cracks. This was most clearly observed on the films deposited on SiO 2 barrier layer and aluminum. The photocatalytic activity of the TiO 2 films deposited on glass with and without SiO 2 barrier layer, ceramic, and aluminum was studied via UV decolorization of methyl orange in aqueous solution. Complete degradation rapidly occurred on the TiO 2 /glass and TiO 2 /SiO 2 barrier layer films, but not with the ceramic or metal substrates. It appears that the photocatalytic activity of the films deposited on aluminum and ceramic substrates was affected by the quantity and the size of the anatase crystallites. The aluminum substrate promoted the formation of TiO 2 films with the largest anatase crystallite size, exhibiting a cracked morphology, where as the ceramic substrate resulted in the formation of TiO 2 films with large crystallite size in an island morphology.
Influence of the structural and surface properties on photocatalytic activity of TiO2:Nd thin films
Polish Journal of Chemical Technology, 2015
Titanium dioxide thin films doped with the same amount of neodymium were prepared using two different magnetron sputtering methods. Thin films of anatase structure were deposited with the aid of Low Pressure Hot Target Magnetron Sputtering, while rutile coatings were manufactured using High Energy Reactive Magnetron Sputtering process. The thin films composition was determined by energy dispersive spectroscopy and the amount of the dopant was equal to 1 at. %. Structural properties were evaluated using transmission electron microscopy and revealed that anatase films had fibrous structure, while rutile had densely packed columnar structure. Atomic force microscopy investigations showed that the surface of both films was homogenous and consisted of nanocrystalline grains. Photocatalytic activity was assessed based on the phenol decomposition. Results showed that both thin films were photocatalytically active, however coating with anatase phase decomposed higher amount of phenol. The t...
Surface and Coatings Technology, 2008
Amorphous and porous TiO 2 coatings were deposited by reactive magnetron sputtering at high pressure (3.4 Pa) on cold soda-lime glass placed at different positions relatively to the magnetron target, which corresponds to different impingement angles and target-to-substrate distances. The as-deposited coatings were heated at 450°C under ambient air to crystallise into the photoactive anatase phase. The structural analyses combined with AFM experiments have shown a reduction of the crystallites and the lateral grain size with the removal of the substrate from the target axis inducing a specific area rise. Moreover, the stress state is all the less as compressive as the substrates are far away from the target. As a result, the photocatalytic properties are improved with the decrease of the incidence angle and with the target-tosubstrate distance rise.
Vacuum, 2005
The reactive magnetron sputtering method was used to prepare pure and Fe-doped titanium dioxide thin films. The films were deposited onto microscope glass slides and polycarbonate plates at different total pressure and Fe-doping concentrations. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectroscopy (UV). For glass substrates a polycrystalline TiO 2 structure was verified with X-ray diffraction, which showed typical characteristic anatase reflections. An iron phase appeared in the highly Fe-doped samples. The absorption edges of the Fe-doped TiO 2 films shifted to visible region with increasing concentration of iron. For the polycarbonate substrate an amorphous TiO 2 structure was revealed for all deposition conditions. The effects of different Fe-doping and total pressure levels on the photocatalytic activity were obtained by the degradation rates of Rhodamine-B (RoB) dye under UV light irradiation. For the deposition conditions considered in this study the highest photodegradation rates were achieved for films deposited on the polymer substrates. Of these overall highest rates was achieved for deposition at 0.4 Pa and without doping. However, for both substrates, films prepared at the particular total pressure of 0.5 Pa and a low iron concentration showed better photocatalytic activity than the pure TiO 2 films prepared under the same deposition parameters. On the contrary, the photocatalytic degradation rates of RoB on the highly Fe-doped TiO 2 films decreased strongly. r
Materials Research Bulletin, 2004
TiO 2 thin-film photocatalysts coated onto glass were prepared either by plasma enhanced chemical vapour deposition (PECVD) deposition or by a dip-coating process using sol-gel solutions. The influence of the addition of a polymer and of a highly viscous solvent on physical properties (thickness, crystallite size and porosity) of TiO 2 thin films and on their photocatalytic efficiency was evaluated.