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1.
This paper describes a procedure of preparing sodium tantalite nanofibers for the first time. Sodium tantalite nanofibers
were synthesised by electrospinning a sol–gel precursor solution of poly(vinyl pyrrolidone)/sodium tantalite, followed by
careful sintering of the as-electrospun composite fibers at 550 °C for 3 h. The morphology, microstructure and crystal phase
were investigated by transmission electron microcopy and X-ray diffraction. The optical property was characterized by ultraviolet–visible
(UV–vis) spectrometer. Typical nanofibers were with diameter between 70 and 90 nm and length exceeding 0.1 mm. An unusual
phenomenon, the red-shift of optical absorption band edge happened, indicated the fabricated NaTaO3 nanofibers were potential good candidates for photocatalytic application. The experiment photodegradation of methylene blue
by NaTaO3 nanofibers under UV light irradiation was performed. 相似文献
2.
J. Bennaceur R. Mechiakh F. Bousbih M. Jaouadi R. Chtourou 《Journal of Sol-Gel Science and Technology》2012,61(1):69-76
Titanium dioxide doped with iron (III) was prepared by sol–gel Spin Coating method. The phase structures, morphologies, particle
size of the doped TiO2 have been characterized by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and ultraviolet–visible
(UV–Vis) spectrophotometer. The XRD and Raman results show that the 10% Fe3+-doped TiO2 thin films crystallize in anatase phase between 600 and 800 °C, and into the anatase–rutile phase at 1,000 °C, and further
into the rutile phase when the content of Fe3+ increases (20%). The grain size calculated from XRD patterns shows that the crystallinity of the obtained anatase particles
increased from 39.4 to 43.4 nm as the temperature of annealing increase, whereas the size of rutile crystallites increases,
with increasing Fe3+ concentrations from 36.9 to 38.1 nm. The AFM surface morphology results confirmed that the particle size increases by increasing
the annealing temperature and also with an increasing of Fe3+ content. The optical band gap (E
g) of the films was determined by the UV–Vis spectrophotometer. We have found that the optical band gap decreased with an increasing
of annealing temperatures and also with an increasing of Fe3+ content. 相似文献
3.
Tao Yuan Zhonglei Wei Jing Yuan Longgang Yan Qingfang Liu Jianbo Wang 《Journal of Sol-Gel Science and Technology》2011,58(2):501-506
Nickel zinc ferrite (Ni0.4Zn0.6Fe2O4) films on Si (100) substrate were synthesized using a spin-coating method. The crystallinity of the Ni0.4Zn0.6Fe2O4 films with the thickness of about 386 nm became better as the annealing temperature increased. The films have smooth surface,
relatively good packing density and uniform thickness. The volatilization of Zn is serious at 900 °C. With the increase of
annealing temperature, the saturation magnetization M
s increases in the temperature ranging from 400 to 700 °C, however, decreases above 700 °C, and the coercivity H
c increases in the temperature range 400–800 °C, decreases above 800 °C. After annealed at 700 °C for 2 h in air with the heating
rate 2 °C/min, the film shows a maximum saturation magnetization M
s of 349 emu/cc and low coercivity H
c of 66 Oe. The M
s is higher than others which prepared by this method, however, the H
c is lower. The M
s of Ni0.4Zn0.6Fe2O4 films annealed at 700 °C increases with increasing annealing time and the H
c changes slightly. 相似文献
4.
P. M. Chavhan R. K. Sharma N. K. Kaushik 《Journal of Sol-Gel Science and Technology》2010,53(3):505-508
The 12BaO·7Al2O3 (B12A7) thin films have been prepared via sol–gel process. Optical and electrical properties of B12A7 films have been investigated.
The films were coated on soda lime float glass by the dip coating process, and annealed in air and hydrogen (H2) at 450 °C for 2 h. The UV absorption edge was red shifted for films annealed in H2 atmosphere. The B12A7 films had high transparency about 90% in wide visible range with maximum of 95% at 575 nm wavelength.
The sheet resistance of the 300 nm films corresponding to 90.57 and 0.974 kΩ per square has been observed for air and H2 annealed, respectively. 相似文献
5.
Nanocrystalline TiO2 powders in the anatase, rutile, and mixed phases prepared by hydrolysis of TiCl4 solution were of ultrafine size (<7.2 nm) with high specific surface areas in the range 167 to 388 m2/g. In the photocatalytic degradation of phenol as model reaction, the photocatalytic properties of TiO2 nanoparticles were evaluated by use of UV–vis absorption spectroscopy and total organic carbon (TOC) content. The synthetic
mixed-phase TiO2 powder calcined at 400 °C had higher activity than pure anatase or rutile; it degraded more than 90% phenol to CO2 (evaluated by TOC) after irradiation with near UV light for 90 min at a catalyst loading of 0.4 g/L. The TOC results indicated
that rutile TiO2 crystallites of particle size 7.2 nm resulted in much better photocatalytic performance than particles of larger size. This
result suggested that some intermediates, not determined by UV–vis absorption spectroscopy, existed in the solution after
the photocatalytic process over the rutile TiO2 photocatalysts of larger crystallite size. 相似文献
6.
Marzieh Daryanavard Hassan Hadadzadeh Aliakbar Dehno Khalaji Matthias Weil 《Transition Metal Chemistry》2009,34(7):779-786
The mononuclear Ru(III) complex, [Ru(bpy)(tppz)Cl][PF6]2.acetylacetone, where tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpy is 2,2′-bipyridine, has been prepared and characterized
by physicochemical and spectroscopic methods, cyclic voltammetry, and single crystal X-ray structure analysis. The coordination
around the Ru(III) center is distorted octahedral, with bite angles of 80.70–161.83° for the chelating bpy and tppz ligands.
The two pyridyl rings of the bpy ligand are nearly coplanar. UV–vis spectroelectrochemical studies of this complex in acetonitrile
showed a reversible redox behavior evaluated by the maintenance of isosbestic points in the UV–vis spectrum for both forward
reduction and reverse oxidation processes. Magnetic susceptibility data derived from paramagnetic NMR data revealed an effective
magnetic moment of 1.79 BM at room temperature. 相似文献
7.
D. Melo R. M. M. Marinho F. T. G. Vieira S. J. G. Lima E. Longo A. G. Souza A. S. Maia I. M. G. Santos 《Journal of Thermal Analysis and Calorimetry》2011,106(2):513-517
Perovskite type oxides have been intensively studied due to their interesting optical, electrical, and catalytic properties.
Among perovskites the alkaline earth stannates stand out, being strontium stannates (SrSnO3) the most important material in ceramic technology among them due to their wide application as dielectric component. SrSnO3 has also been applied as stable capacitor and humidity sensor. In the present work, SrSnO3:Cu was synthesized by polymeric precursor method and heat treated at 700, 800, and 900 °C for 4 h. After that, the material
was characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared spectroscopy, and UV–vis spectroscopy. Results
indicated three thermal decomposition steps and confirmed the presence of strontium carbonate and Cu2+ reduction to Cu+ at higher dopant amounts. XRD patterns indicated that the perovskite crystallization started at 700 °C with strontiatite
(SrCO3) and cassiterite (SnO2) as intermediate phases, disappearing at higher temperatures. The amount of secondary phase was reduced with the increase
in the Cu concentration. 相似文献
8.
I. John Berlin J. S. Lakshmi S. Sujatha Lekshmy Georgi P. Daniel P. V. Thomas K. Joy 《Journal of Sol-Gel Science and Technology》2011,58(3):669-676
Transparent nanocrystalline zirconia thin films were prepared by sol–gel dip coating technique using Zirconium oxychloride
octahydrate as source material on quartz substrates, keeping the sol at room temperature (SET I) and 60 °C (SET II). X-ray
diffraction (XRD) pattern shows the formation of mixed phase [tetragonal (T) + monoclinic (M)] in SET I and a pure tetragonal
phase in SET II ZrO2 thin films annealed at 400 °C. Phase transformation from tetragonal to monoclinic was achieved in SET II film annealed at
500 °C. Atomic force microscopy analysis reveals lower rms roughness and skewness in SET II film annealed at 500 °C indicating
better optical quality. The transmittance spectra gives a higher average transmittance >85% (UV–VIS region) in SET II films.
Optical spectra indicate that the ZrO2 films contain direct—band transitions. The sub- band in the monoclinic ZrO2 films introduced interstitial O−defect states above the top of the valance band. The energy bandgap increased (5.57–5.74 eV) in SET I films and decreased
(5.74–5.62 eV) in SET II films, with annealing temperature. This is associated with the variations in grain sizes. Photoluminescence
(PL) spectra give intense band at 384 and 396 nm in SET I and SET II films, respectively. A twofold increase in the PL intensity
is observed in SET II film. The “Red” shift of SET I films and “Blue” shift of SET II films with annealing temperature, originates
from the change of stress of the film due to lattice distortions. 相似文献
9.
E. Ramírez-Meneses A. García-Murillo F. de J. Carrillo-Romo R. García-Alamilla P. Del Angel-Vicente J. Ramírez-Salgado P. Bartolo Pérez 《Journal of Sol-Gel Science and Technology》2009,52(2):267-275
Titania thin films were synthesized by sol–gel dip-coating method with metallic Ni nanoparticles synthesized separately from
an organometallic precursor Ni(COD)2 (COD = cycloocta-1,5-diene) in presence of 1,3-diaminopropane as a stabilizer. Titania was obtained from a titanium isopropoxide
precursor solution in presence of acetic acid. A Ni/TiO2 sol system was used to coat glass substrate spheres (6, 4 and 3 mm diameter sizes), and further heat treatment at 400 °C
was carried out to promote the crystallization of titania. XRD analysis of the TiO2 films revealed the crystallization of the anatase phase. Transmission Electron Microscopy (TEM) and High Resolution TEM studies
of Ni nanoparticles before mixing with the TiO2 solution revealed the formation of Ni nanostructures with an average size of 5–10 nm. High-angle annular dark-field images
of the Ni/TiO2 system revealed well-dispersed Ni nanoparticles supported on TiO2 and confirmed by AFM analysis. The photocatalytic activity of the Ni/TiO2 films was evaluated in hydrogen evolution from the decomposition of ethanol using a mercury lamp for UV light irradiation.
Titania films in presence of Ni nanoparticles show higher efficiency in their photocatalytic properties in comparison with
TiO2. 相似文献
10.
Hui Li Jinshu Wang Hongyi Li Shu Yin Tsugio Sato 《Research on Chemical Intermediates》2010,36(1):27-37
Nitrogen and sulfur co-doped mesoporous TiO2 thin films were fabricated using thiourea as a doping resource by the combination of the sol–gel and evaporation-induced
self-assembly (EISA) processes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy
(XPS), N2 adsorption–desorption, and UV–vis spectra were performed to characterize the as-synthesized mesoporous TiO2 materials. The XPS result shows that O–Ti–N and O–Ti–S bonds in the (S, N)-codoped mesoporous TiO2 were formed. The resultant mesoporous (S, N)-codoped TiO2 exhibited anatase framework with a high porosity and a narrow pore distribution. After being illuminated for 3 h, methyl
orange (MO) could be degraded completely by the co-doped sample under the ultraviolet irradiation, whereas mesoporous TiO2 film without doping could only degrade 60% MO. After being illuminated by visible light, the water contact angles of the
mesoporous co-doped TiO2 samples decreased slightly, but the pure TiO2 mesoporous film exhibited no change in the hydrophilicity. 相似文献
11.
Andres Trikkel Merli Keelmann Tiit Kaljuvee Rein Kuusik 《Journal of Thermal Analysis and Calorimetry》2010,99(3):763-769
In the present research, CO2 and SO2 binding ability of different oil shale ashes and the effect of pre-treatment (grinding, preceding calcination) of these ashes
on their binding properties and kinetics was studied using thermogravimetric, SEM, X-ray, and energy dispersive X-ray analysis
methods. It was shown that at 700 °C, 0.03–0.28 mmol of CO2 or 0.16–0.47 mmol of SO2 was bound by 100 mg of ash in 30 min. Pre-treatment conditions influenced remarkably binding parameters. Grinding decreased
CO2 binding capacities, but enhanced SO2 binding in the case of fluidized bed ashes. Grinding of pulverized firing ashes increased binding parameters with both gases.
Calcination at higher temperatures decreased binding parameters of both types of ashes with both gases studied. Clarification
of this phenomenon was given. Kinetic analysis of the binding process was carried out, mechanism of the reactions and respective
kinetic constants were determined. It was shown that the binding process with both gases was controlled by diffusion. Activation
energies in the temperature interval of 500–700 °C for CO2 binding with circulating fluidized bed combustion ashes were in the range of 48–82 kJ mol−1, for SO2 binding 43–107 kJ mol−1. The effect of pre-treatment on the kinetic parameters was estimated. 相似文献
12.
Tongjit Kidchob Luca Malfatti Daniela Marongiu Stefano Enzo Plinio Innocenzi 《Journal of Sol-Gel Science and Technology》2009,52(3):356-361
The process of formation of cerium titanate films as a function of annealing temperature and composition has been studied
by combining X-ray diffraction analysis and far infrared spectroscopy. The films have been prepared by a sol–gel synthesis
using metal chlorides as precursors; the synthesis allows obtaining cerium titanate films upon annealing in air. A brannerite
type, CeTi2O6, phase has been identified by X-ray diffraction and Rietveld analysis on thin films. CeTi2O6 is formed upon annealing at 700 °C and in a limited range of ceria-titania mixed compositions. The far infrared spectra are
useful to observe the formation of crystalline phases at the beginning of the crystallization process at lower firing temperatures,
when the XRD analysis is not enough sensitive. 相似文献
13.
V. H. Martínez-Landeros Bruce E. Gnade M. A. Quevedo-López R. Ramírez-Bon 《Journal of Sol-Gel Science and Technology》2011,59(2):345-351
In this work we report the performance of permeation barriers based on organic/inorganic multilayer stacks. We have used PMMA-SiO2 (poly methyl methacrylate-silica) hybrid films synthesized through a sol–gel route as organic–inorganic components, whereas
Al2O3 thin films were used as the inorganic component. The hybrid layers were deposited by dip coating and the Al2O3 by atomic layer deposition (ALD), films were prepared on polyethylene naphthalene (PEN) substrates. The permeability of the
films and stacks is evaluated using helium as the diffusion gas in a custom made ultra-high vacuum system. The results show
that permeability for PEN is reduced from 5 × 10−3 g/m2-day to about 9 × 10−5 g/m2-day for the best multiple barrier evaluated. Increased barrier properties are due to the increasing in the path and hence
the lag-time of the permeating gas. In particular, we report the surface roughness of the different layers and its impact
on the barrier performance. The hybrid layers reduced notably the roughness of the bare PEN substrate improving the quality
of the Al2O3 layer in the barrier. The optical transmittance of the barriers in the visible region is higher than 80% in all the studied
cases. 相似文献
14.
Deuk Yong Lee Kyong-Ho Lee Myung-Hyun Lee Nam-Ihn Cho Bae-Yeon Kim 《Journal of Sol-Gel Science and Technology》2010,53(1):43-49
Ba1−x
Sr
x
TiO3(x = 0–0.5, BST) nanofibers with diameters of 150–210 nm were prepared by using electrospun BST/polyvinylpyrrolidone (PVP) composite
fibers by calcination for 2 h at temperatures in the range of 650–800 °C in air. The morphology and crystal structure of calcined
BST/PVP nanofibers were characterized as functions of calcination temperature and Sr content with an aid of XRD, FT-IR, and
TEM. Although several unknown XRD peaks were detected when the fibers were calcined at temperatures less than 750 °C, they
disappeared with increasing the temperature (above 750 °C) due to its thermal decomposition and complete reaction in the formation
of BST. In addition, the FT-IR studies of BST/PVP fibers revealed that the intensities of the O–H stretching vibration bands
(at 3430 and 1425 cm−1) became weaker with increasing the calcination temperature and a broad band at 540 cm−1, Ti–O vibration, appeared sharper and narrower after calcination above 750 °C due to the formation of metal oxide bonds.
However, no effect of Sr content on the crystal structure of the composites was detected. 相似文献
15.
N, B, Si-tridoped mesoporous TiO2, together with N-doped, N, B-codoped and N, Si-codoped TiO2, was prepared by a modified sol–gel method. The samples were characterized by wide-angle X-ray diffraction (WAXRD), N2 adsorption–desorption, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, UV–visible
adsorbance spectra (UV–vis) and X-ray photoelectron spectra (XPS). The N, B, Si-tridoped mesoporous TiO2 showed small crystallite size, large specific surface area (350 m2/g), uniform pore distribution (3.2 nm) and strong absorption in the visible light region. The photocatalytic activities of
the samples were evaluated by the photodegradation of 2,4-dichlorophenol (2,4-DCP) aqueous solution. The N, B, Si-tridoping
sample exhibited much higher photocatalytic activity compared with other synthesized photocatalysts. The high activity could
be attributed to the strong absorption in the visible light region, large specific surface area, small crystallite size, large
amount of surface hydroxyl groups, and mesoporosity. 相似文献
16.
Shih-Yuan Lin Ying-Chung Chen Chih-Ming Wang Chan-Chih Liu 《Journal of Solid State Electrochemistry》2008,12(11):1481-1486
Electrochromic titanium oxide (TiO2) films were deposited on ITO/glass substrates by chemical solution deposition (CSD). The stock solutions were spin-coated
onto substrates and then heated at various temperatures (200–500 °C) in various oxygen concentrations (0–80%) for 10 min.
The effects of the processing parameters on the electrochromic properties of TiO2 films were investigated. X-ray diffraction measurements demonstrated that the amorphous TiO2 films were crystallized to form anatase films above 400 °C. The electrochromic properties and transmittance of TiO2 films were measured in 1 M LiClO4–propylene carbonate (PC) non-aqueous electrolyte. An amorphous 350 nm-thick TiO2 film that was heated at 300°C in 60% ambient oxygen exhibited the maximum transmittance variation (ΔT%), 14.2%, between the bleached state and the colored state, with a ΔOD of 0.087, Q of 10.9 mC/cm2, η of 7.98 cm2/C and x in Li
x
ClO4 of 0.076 at a wavelength (λ) of 550 nm. 相似文献
17.
Tatiana Nedoseykina Pavel Plyusnin Yuri Shubin Sergey Korenev 《Journal of Thermal Analysis and Calorimetry》2010,102(2):703-708
Thermolysis of double complex salt [Pd(NH3)4][AuCl4]2 has been studied in helium atmosphere from ambient to 350 °C. The XAFS of Pd K and Au L3 edges and thermogravimetry measurements have been carried out to characterize the intermediates and the final product. In
the temperature range 115–160 °C the complex is decomposed to form Pd(NH3)2Cl2 and AuCl4−x
N
x
species with x ranging from 2 to 3. Subsequent heating of the intermediate up to 300 °C leads to the total loss of NH3. The Au–Cl and Au–Au bonds form the local environment of Au at the stage of decomposition while only four chlorine atoms
are around Pd. At the temperature of 330 °C the Au and Pd nanoparticles as well as residues of palladium chloride are detected.
The final product consists of separated Au and Pd nanoparticles. 相似文献
18.
CuCrO2 and CuCrO2:Mn thin films were prepared on sapphire substrates by chemical solution deposition method. The effects of the annealing temperatures
and Mn concentration on the structural, electrical and optical properties were investigated. The X-ray diffraction measurement
was used to confirm the c-axis orientation of CuCrO2 and CuCrO2:Mn thin films. The maximum transmittances of the films in the visible region are about 65% with direct band gaps of 3.25 eV.
All films showed the p-type conduction and semiconductor behavior. The electrical conductivity decreases rapidly with the
increase of Mn content, the maximum of the electrical conductivity of 1.35 × 10−2 S cm−1 is CuCrO2 film deposited at 600 °C temperature in 10−3 Torr vacuum, which is about four orders of magnitude higher than that of the Mn-doped CuCrO2 thin film. The energy band of the samples is constructed based on the grain-boundary scattering in order to investigate the
conduction mechanism. Moreover, the samples exhibit a clear ferromagnetism, which was likely ascribed to originating from
the double-exchange interaction between the Mn3+ and Cr3+ ions. 相似文献
19.
María Luisa Ojeda Monserrat Bizarro Antonio Campero 《Journal of Sol-Gel Science and Technology》2011,60(2):108-115
Nanostructured TiO2 films were synthesized by a modified sol–gel method using Pluronics P-123 (EO20PO70EO20) as templating agent, titanium n-butoxide [Ti(OC4H9)4] as inorganic precursor, and ammonium fluoride (NH4F) as the source of N and F dopant atoms in order to prepare sols of x(NF) TiO2 (x=2, 5, 10, 20 wt%). The thin film preparation was made by spin coating, followed by calcination at 400 °C. The as-prepared
TiO2 and xNF-TiO2 films were characterized by XRD, Raman spectroscopy, FTIR, TGA-DTA, SEM, UV–Vis diffuse reflectance spectroscopy and EPR.
XRD and Raman spectroscopy show that the crystalline structure of these samples consists exclusively of the anatase phase.
The band gap (E
g
) values for the doped 10 and 20 NF-TiO2 film systems were found to be significantly smaller than those corresponding to the rest of the other TiO2 films. The photocatalytic properties of these films are investigated by following the degradation of methyl orange in aqueous
solution under UV irradiation. The photodecomposition is mainly a direct function of the amount of NF present in the TiO2 matrix. The 20NF-TiO2 sample shows the highest activity of all the samples studied. 相似文献
20.
The reactions of [RuCl2(PPh3)3] with 8-hydroxy-2-methyl-quinoline-7-carboxylic acid was examined, and a novel ruthenium(II) complex—[Ru(PPh3)2(C5H8NO)2]—was obtained. The compound was studied by IR, UV–vis spectroscopy, and X-ray crystallography. The molecular orbital diagram
of the complex was calculated with the density functional theory (DFT) method. The spin-allowed singlet–singlet electronic
transitions of the compound were calculated using the time-dependent DFT method, and the UV–vis spectrum of the compound was
discussed, on this basis. The luminescence property of the [Ru(PPh3)2(C5H8NO)2]was examined. 相似文献