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1.
Titanium dioxide (TiO2) thin films have been deposited on silicon and glass substrates by the sol-gel process using titanium iso-propoxide [Ti(O-i-C3H7)4]. The bond configuration of the TiO2 thin films was analyzed by using FTIR in the wavenumber range from 400 to 4000 cm–1. The spectral transmittance of as-deposited TiO2 films deposited on fused silica glass was measured in the wavelength range from 200 to 900 nm. X-ray diffraction measurements were performed to determine the crystallinity of the TiO2 films. As-deposited films were amorphous. As the film was annealed at higher temperature, the structure was transformed from amorphous to the anatase crystalline state. The chemical composition of the deposited film was investigated using X-ray photoelectron spectroscopy (XPS). The films are essentially stoichiometric with carbon as the dominant impurity on the surface. Raman spectra show the characteristic of TiO2 anatase phase. The electrical properties of the TiO2 films were measured using capacitance-voltage (C-V) and current-voltage techniques. From C-V measurements, the dielectric constants were calculated to be approximately 26 for the as-deposited films and 75–82 for films annealed at 700°C in different atmosphere. For the as-deposited samples, the breakdown voltage was 2.7 MV/cm, and for an electric field of 1 MV/cm, the leakage current was 5 × 10–5 A/cm2 and the resistivity was 2.2 × 1010 -cm. 相似文献
2.
Maria Zaharescu Maria Crisan I. MuŠeviČ 《Journal of Sol-Gel Science and Technology》1998,13(1-3):769-773
Atomic Force Microscopy (AFM) was used to study the influence of thermal treatments on the structural and textural properties of the sol-gel TiO2 films obtained from Ti(OC3H7i)4. X-ray diffraction (XRD), ellipsometric and porosity measurements have also been made.The TiO2 sol-gel films were homogeneous, transparent and amorphous. Heat treatments in the 400–600°C range indicate that the films have a strong tendency to crystallization. The high initial homogeneity of the TiO2 films was preserved during the crystallization process. AFM shows that the thermally treated films exhibit uniform, monodispersed crystals. 相似文献
3.
Djaoued Y. Badilescu Simona Ashrit P.V. Bersani D. Lottici P.P. Brüning R. 《Journal of Sol-Gel Science and Technology》2002,24(3):247-254
TiO2 nanocrystalline thin films with varying degree of porosity have been prepared using a low temperature method. TiO2 films of the anatase form have been obtained by using a polyethylene glycol (PEG) modified sol-gel method. Densification and crystallization of the films was found to result from the thermal treatment of the dip coated films in boiling water. The films have been characterized by Raman, XRD, FTIR, AFM and optical methods. Highly transparent films with transmission in excess of 85% and porosity as high as 58% are formed predominantly of anatase crystallites of dimensions of the order of 5 nm. Initial results on lithium intercalation into these films resulting in an efficient optical modulation in the visible and near infrared regions demonstrate a good potential of these films for electrochromic applications. 相似文献
4.
R. Sirera M.L. Calzada J. Ricote L. Pardo 《Journal of Sol-Gel Science and Technology》1997,8(1-3):425-430
A sol-gel route is developed for the synthesis of samarium modified lead titanate precursor solutions. The solutions are used
for the deposition of thin films. After thermal treatment of the films, two crystalline phases are observed by X-ray diffraction
analysis: an undesirable pyrochlore phase and a ferroelectric perovskite. These two phases are clearly distinguished in the
film microstructure, showing a fined grained fraction of pyrochlore anda-axis oriented rosette grains of perovskite. The development of these phases as well as the evolution of the perovskite/pyrochlore
ratio in the films is related to the chemistry of the synthesized solutions and the thermal treatment used for crystallization. 相似文献
5.
Photocatalytic Activity and Characterization of the Sol-Gel Derived Pb-Doped TiO2 Thin Films 总被引:1,自引:0,他引:1
Yu Jiaguo Yu Jimmy C. Cheng Bei Zhao Xiujian 《Journal of Sol-Gel Science and Technology》2002,24(1):39-48
Photocatalytically active Pb-doped TiO2 thin films were prepared on a soda-lime glass substrate by sol-gel dip-coating technique using TiO2 sols containing lead(II) nitrate. The thin films were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-VIS spectroscopy and X-ray diffraction (XRD). A shift of the UV-VIS absorption towards longer wavelengths was observed, which indicated a decrease in the band-gap of TiO2 upon Pb doping. XRD results showed both pure and Pb-doped TiO2 thin films were polycrystalline, anatase type, and oriented predominantly to the (101) plane. A slight shift in the d-spacing for the Pb-doped film indicated the incorporation of Pb into the TiO2 lattice to form Pb
x
Ti1–x
O2 solid solution. AFM results showed Pb-doped TiO2 thin films were composed of larger TiO2 particles and had rougher surface, compared with un-doped TiO2 thin films. XPS results showed that except for the enrichment of Pb near the surface, Pb exists in the forms of Pb
x
Ti1–x
O2 and PbO. Dimethyl-2,2-dichlorovinyl phosphate (DDVP) was efficiently degraded in the presence of the Pb-doped TiO2 thin films by exposing the insecticide solution to sunlight. The mechanism of photocatalytic activity enhancement of the Pb-doped TiO2 thin films was discussed. 相似文献
6.
Crystallization Behavior of SiO2-TiO2 Sol-Gel Thin Films 总被引:1,自引:0,他引:1
The aim of this work was to investigate the crystallization behavior of thin films of SiO2−TiO2 made by the sol-gel process as function of the TiO2 content and the temperature and time of heat treatment. Precursor solutions were prepared by hydrolysis of TEOS (tetraethoxysilane)
and TPOT (titaniums tetraisopropoxide). Multilayer films were spun on single crystal silicon wafers. The compositions studied
were (on a molar percentage basis) 20TiO2−80SiO2, 30TiO2−70SiO2, 40TiO2−60SiO2 and pure TiO2. The films were heat treated at different temperatures between 300°C and 1200°C, for different periods of time (30 s-90 h).
The crystallization kinetics were followed by micro-Raman spectrometry. Grazing incidence X-ray diffraction showed that the
films crystallized into one or both of two crystalline phase of TiO2: anatase and rutile (for pure TiO2 only). The volume fractions of the crystalline phase varied from very low values (<1%), up to 100%, for a TiO2 sample heat treated at 800°C for 8 hours. The results show that the volume fraction of crystalline phase is strongly influenced
by the heat treatment temperature and also, to a smaller extent, by the heat treatment time. The most important parameter,
however, is the composition of the films: the higher their TiO2 concentration, the lower is the crystallization temperature and the larger is the crystallized fraction. 相似文献
7.
Zhifeng Liu Zhengguo Jin Xiaoxin Liu Yanan Fu Guoqi Liu 《Journal of Sol-Gel Science and Technology》2006,38(1):73-78
Monolayer polystyrene spheres (∼400 nm) array templates were assembled orderly on clean glass substrates by dip-drawing method
from emulsion of PS and porous TiO2 thin films were prepared by using sol-dipping template method to fill TiO2 sol into the interstices among the close-packed PS templates and then annealing to remove the PS templates. The effects of
TiO2 precursor sol concentration and dipping time in sol on the porous structure of the thin films were studied. The results showed
pore size of the ordered TiO2 porous thin film depended mainly on PS size and partly on TiO2 sol concentration. The shrinkage of pore diameter was about 10% for 0.2 M and 20% for 0.4 M TiO2 sol concentrations. X-ray diffraction (XRD) spectra indicated the porous thin film was anatase structure. The transmittance
spectrum showed that optical transmittance of the porous thin film kept above 70% beyond the wavelength of 430 nm. Optical
band-gap of the porous TiO2 thin film (fired at 550∘;C) was 3.12 eV. 相似文献
8.
Xiaorong Fu Zhitang Song Guangming Wu Jipo Huang Xinzhong Duo Chenglu Lin 《Journal of Sol-Gel Science and Technology》1999,16(3):277-281
MgO thin films have been prepared on Si substrates by a novel and simple sol-gel method using magnesium nitrate and collodion as starting material. Solutions consisting of magnesium nitrate in a mixture of collodion and ethanol were spin-coated onto silicon substrates. It was found that collodion was a necessary component to form stable sols and the crystallization and structures were clearly dependent on the amount of the collodion and the annealing temperature. The MgO thin films with good crystallization were obtained after annealing at 800°C. Meanwhile, the microstructure of the MgO films was examined by transmission electron microscopy and atomic force microscopy. 相似文献
9.
Sun Jiebing Xiong Rui Wang Shimin Tang Wufeng Tong Hua Shi Jing 《Journal of Sol-Gel Science and Technology》2003,27(3):315-319
This paper presents a new sol-gel process to prepare molybdenum oxide thin films. A molybdenum acetylacetonate sol was prepared by employing the system CH3COCH2COCH3/MoO3/C6H5CH3/HOCH2CH2OCH3. A molybdenum acetylacetonate gel was prepared by addition of aqueous NH3. Thermal gravimetry (TG) and differential thermal analyses (DTA) of the gel suggested that crystallization of MoO3 occurs in a 140 K temperature range around 508°C. MoO3 films were prepared on fused silica, Si (111) and Al2O3 (012) substrates by annealing spin coating films of the sol in oxygen environment at 508°C. X-ray diffraction (XRD) showed that all films crystallize in -MoO3 structure, and crystallites on fused silica substrate are arbitrarily oriented while those on Si (111) and Al2O3(012) substrates oriented in the (010) direction. SEM investigations showed that MoO3 grains of all films are randomly distributed, with a longitudinal dimension of about 1–5 m and the film thickness is about 1 m. 相似文献
10.
The influence of humidity upon the macroporous morphology of the titania films has been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The water adsorption from the ambient atmosphere modifies the polycondensation rate of TiO2 oligomer and the phase separation rate between the TiO2-PEG complex and solvent mixture, and greatly varies the macroscopic morphology of the resultant TiO2 film. 相似文献
11.
M. Langlet A. Kim M. Audier J.M. Herrmann 《Journal of Sol-Gel Science and Technology》2002,25(3):223-234
Sol-gel TiO2 thin films were autoclaved under various water/ethanol atmospheres. The microstructural, morphological and photocatalytic properties of the films were studied. The photocatalytic activity of the films appears closely related to crystallization states. It is shown that nanocrystallized porous films can be produced in a temperature range compatible with titania deposition on polymer materials. Consequently, photocatalytic films could successfully be prepared on polycarbonate and polymethylmetacrylate substrates. The autoclaved film properties are described and discussed with respect to sol-gel parameters and autoclaving conditions. 相似文献
12.
AFM has been utilized to study the surface topography and the local conductivity of nanocrystalline TiO2 films. Improving the local conductivity by Ti(iso-C3H7O4) treatment is characterized by quantitative analysis of the simultaneous current image. The mechanism of Ti(iso C3H7O4)4 treatment is discussed. 相似文献
13.
Hong Li Dr. Yi Jia Dr. Mingchun Du Dr. Jinbo Fei Dr. Jie Zhao Dr. Yue Cui Prof. Dr. Junbai Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(17):5306-5313
This study describes a facile breath‐figure method for the preparation of honeycomb‐like porous TiO2 films with an organometallic small‐molecule precursor. Multiple characterization techniques have been used to investigate the porous films and a mechanism for the formation process of porous TiO2 films through the breath‐figure method is proposed. The pore size of the TiO2 films could be modulated by varying the experimental parameters, such as the concentration of titanium n‐butoxide (TBT) solution, the content of cosolvent, and the air flow rate. In vitro cell‐culture experiments indicate that NIH 3T3 fibroblast cells seeded on the honeycomb‐like porous TiO2 films show good adhesion, spreading, and proliferation behaviors, which suggests that honeycomb‐like porous TiO2 films are an attractive biomaterial for surface modification of titanium and its alloys implants in tissue engineering to enhance their biocompatibility and bioactivity. 相似文献
14.
J.H. Yi P. Thomas M. Manier J.P. Mercurio I. Jauberteau R. Guinebretière 《Journal of Sol-Gel Science and Technology》1998,13(1-3):885-888
Pure SrBi2Nb2O9 powders and thin films were obtained using sol-gel synthesis from mixtures of niobium ethoxide, bismuth and strontium 2-ethylhexanoates. Powders crystallized for 2 hours at 700°C had grain sizes of about 100–150 nm. SrBi2Nb2O9 thin films were prepared by spin-coating a stable precursor solution onto Si/SiO2/TiO2/Pt substrates. Crystallization of pure SrBi2Nb2O9 phase occurred at about 500–550°C. Randomly oriented 0.3 m-thick crack-free films were obtained after 10 successive depositions and heating at 700°C for 2 hours. P-E hysteresis loops have confirmed the ferroelectric behavior of the films: they show a remanent polarization of 2.5 C/cm2 (5 V, 8 ms). No fatigue was observed up to 109 full switchings. 相似文献
15.
The influences of water and alkoxide concentrations, as well as the relative humidity upon the macroporous morphology of the titania (TiO2) films have been studied for a sol-gel dip-coating system containing poly(ethylene glycol) (PEG). The distribution of resultant morphology against the withdrawal speed and relative humidity is varied significantly by mainly modifying the polycondensation and phase separation processes during the dipping operation, even by the small change in starting composition of the dipping solution. 相似文献
16.
Osamu Sugiyama Yasuhiro Kondo Hisao Suzuki Shoji Kaneko 《Journal of Sol-Gel Science and Technology》2003,26(1-3):749-752
The crystalline phase and composition of sol-gel-derived lead zirconate titanate (PbZr
x
Ti1 – x
O3, PZT) thin films were determined by an X-ray photoelectron spectroscopic (XPS) data processing technique. As a result, it was proved that existence of the surface layer with several tens nm in thickness, of which the crystalline phase and composition were different from those of the inside of the thin films, was found. The newly developed XPS analytical technique is much applicable for the characterization of PZT thin film surface. 相似文献
17.
通过原子力显微镜研究了二氧化钛纤维表面担载Pt的表面形貌及其结构.结果表明,TiO2纤维表面担载的Pt具有微米尺度的近似六边形或者近似长方形的结构,与在单晶TiO2(110)表面的Pt纳米簇形貌相似,但尺度较大.TiO2纤维担载的Pt表面明显存在不同高度的台阶结构,台阶高度以2~4倍Pt(111)晶面面间距的高度为主.由Pt在TiO2纤维表面的形貌与纤维的纳米晶粒排布有序性推测可知,Pt与TiO2纤维存在强的相互作用,可能正是这种强相互作用和表面台阶结构才使TiO2表面担载的Pt虽是微米尺寸但仍具有高光催化活性. 相似文献
18.
19.
The third-order nonlinear optical properties of the sol-gel derived Pb(Fe1/2Nb1/2)O3-PbTiO3 (PFN-PT) thin films have been investigated by the THG method. The χ(3) values of PFN-PT thin films increased from 3.2×10−12 esu (PT) to 8.5×10−12 esu (PFN) with increasing content of Fe3+ ions which possessed very high second-hyperpolarizability, ψ(Fe2/3O). It was experimentally confirmed that complex oxides such as ABO3-type perovskites consisting of large non-transition metal A-site cations and small transition metal B-site cations exhibited
high χ(3) as expected from Lines' model. It was also found that the χ(3) values of complex oxides could be estimated from the second-hyperpolarizabilities of the constituent single oxides reported
so far. Because of the large remanent polarization, PT thin films may exhibit the highest χ(3) among the ferroelectric PFN-PT thin films studied in the present work. The maximum dielectric constant, ε, of 1990 at room
temperature was obtained for 0.5PFN·0.5PT thin films, whose composition corresponds to so-called morphotropic phase boundary
(MPB). 相似文献
20.
Atomic Force Microscopy Studies of SnO2 Thin Film Microstruc tures Deposited by Atomic Layer Epitaxy
Mikko Utriainen Hanna Lattu Heli Viirola Lauri Niinistö Roland Resch Gernot Friedbacher 《Mikrochimica acta》2000,133(1-4):119-123
ALE-grown, rutile-type SnO2 thin films and gas sensor structures based thereupon were studied by AFM with main emphasis on cross-sectional investigations
(X-AFM). On glass substrates the polycrystalline films showed a preferred orientation which depended on the film thickness
and growth temperature while on single crystal sapphire () the growth was heteroepitaxial. For the X-AFM studies various sample preparation techniques were investigated but only ion
beam etching gave satisfactory results and revealed substructures in the sensor structure consisting of Pt and SnO2 layers on a silicon substrate. 相似文献