共查询到20条相似文献,搜索用时 15 毫秒
1.
Masoud Salavati-Niasari Fatemeh Davar Masoud Farhadi 《Journal of Sol-Gel Science and Technology》2009,51(1):48-52
Nanocrystalline Copper aluminate (CuAl2O4) was prepared by sol–gel technique using aluminum nitrate, copper nitrate, diethylene glycol monoethyl ether and citric acid
were used as precursor materials. This method starts from of the precursor complex, and involves formation of homogeneous
solid intermediates, reducing atomic diffusion processes during thermal treatment. The formation of pure crystallized CuAl2O4 nanocrystals occurred when the precursor was heat-treated at 600 °C in air for 2 h. The stages of the formation of CuAl2O4, as well as the characterization of the resulting compounds were done using thermo–gravimetric analysis, X-ray diffraction,
scanning electron microscopy and Fourier transform infrared spectroscopy. The products were analyzed by transmission electron
microscopy and ultraviolet–visible (UV–Vis) spectroscopy to be round, about 17–26 nm in size and E
g = 2.10 eV. 相似文献
2.
C. Aydın Sh. A. Mansour Z. A. Alahmed F. Yakuphanoglu 《Journal of Sol-Gel Science and Technology》2012,62(3):397-403
Pure and boron (B) doped iron oxide (Fe2O3) nanostructured thin films were prepared by sol–gel spin coating method. The effects of B (0.1, 0.2, 0.5 and 1 %) content
on the crystallinity and morphological properties of Fe2O3 films were investigated by X-ray diffractometer and atomic force microscopy. X-ray diffraction patterns revealed that the
Fe2O3 films have a rhombohedral crystalline phase of α-Fe2O3 phase (hematite) with nanostructure and their crystallite size (D) is changed from 27 ± 2 to 45 ± 5 nm with B dopant content.
The minimum crystallite size value of 27 ± 2 nm was obtained for 0.2 % B doped Fe2O3 film. Carrying out UV–VIS absorption study for both doped and undoped films at room temperature, it was realized that allowed
optical transitions may be direct or indirect transitions. The direct and indirect energy gap values for pure Fe2O3 were obtained to be 2.07 and 1.95 eV, respectively. The optical band gap value of the films was changed with 0.1 % B doping
to reach 1.86 eV for direct band gap and 1.66 eV in case of indirect band gap. 相似文献
3.
M. Baikousi S. Agathopoulos I. Panagiotopoulos A. D. Georgoulis M. Louloudi M. A. Karakassides 《Journal of Sol-Gel Science and Technology》2008,47(1):95-101
Magnetic bioglasses in the system CaO–SiO2–P2O5 were prepared by interaction of acetic acid vapors with iron nitrate dispersed on the surface of sol–gel derived porous silicate
network. Upon pyrolysis, the created iron acetate species transform into magnetic iron oxide nanoparticles. X-ray diffraction
(XRD), FT-infrared (FT-IR) spectroscopy and surface area measurements (BET) were employed to monitor the evolution of glass
structural features during the synthetic pathway as well as the structure and the texture of the resultant glasses. XRD, Raman
spectroscopy and vibration magnetic measurements (VSM) revealed the features of magnetic phases, developed in the form of
γ-Fe2O3 and magnetite. The obtained glasses exhibit in vitro bioactivity, expressed by spontaneous formation of hydroxyapatite on
their surface after immersion in SBF at 37 °C, confirmed with μ-Raman and FT-IR spectroscopies. 相似文献
4.
I. Prakash N. Nallamuthu P. Muralidharan M. Venkateswarlu Manjusri Misra Amar Mohanty N. Satyanarayana 《Journal of Sol-Gel Science and Technology》2011,58(1):24-32
In situ base catalyst assisted sol–gel process is used for the synthesis of nanocrystalline CoFe2O4 deposition on SiO2 particles. The SiO2 particles were prepared using base catalyst assisted sol–gel process and the consecutive formation and deposition of nanocrystalline
CoFe2O4 on SiO2 particles was monitored using Powder X ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric
And Differential Thermal Analysis (TG/DTA), Scanning Electron Microscopy and Energy Dispersive X ray Spectroscopy (SEM–EDS)
and High Resolution Transmission Electron Microscopy (HRTEM). The crystallite size of CoFe2O4 is calculated using Scherrer’s formula and it is found to be 8 nm. The HRTEM images and selective area electron diffraction
(SAED) results confirmed the formation of nanocrystalline CoFe2O4 particles deposited over SiO2 spheres. 相似文献
5.
Wen Wang Jian-Cun Rao Hua Ke Ming Feng Rui-Lin Xia Qing-Chang Meng De-Chang Jia Yu Zhou 《Journal of Sol-Gel Science and Technology》2010,56(1):87-92
We report the independent invention of perovskite ferroelectric nanowires strontium bismuth tantalate (SrBi2Ta2O9, SBT). Electrophoretic sol–gel techniques have been used successfully. The morphology and structures are analyzed via SEM,
TEM and XRD. SBT nanowires and nanoparticles filled template revealed 30 and 40 μm long, respectively. SBT are proved to be
a single phase of orthorhombic perovskite structure. As it indicated, SBT nanowires has been crystallized at 700 °C. To minimize
surface polarity, SBT nanowires oriented preferentially along the growing axis (c axis) by translation and rotation of atomic clusters of SBT. 相似文献
6.
Haiyan Xia Yunzhe Ye Longgang Yan Qingfang Liu Jianbo Wang Desheng Xue 《Journal of Sol-Gel Science and Technology》2012,61(1):39-43
Ba2Co2Fe12O22 (Co2Y) was synthesized by sol–gel method using glucose as chelating agent. X-Ray diffraction studies indicate that sintering temperature
as low as 950 °C is sufficient to produce Co2Y ferrites. Co2Y ferrites calcined at 1,000 °C exhibit good magnetic prosperities in high frequency, with the resonance frequency up to 11 GHz
and intrinsic permeability about 5 even at 6 GHz. The heat-treated temperature dependence of coercivity, initial permeability
and resonance frequency is close related to the particle shape and size. 相似文献
7.
Lifeng Cao Lingxia Li Ping Zhang Haitao Wu 《Journal of Sol-Gel Science and Technology》2009,51(2):251-254
Perovskite-type Ag(Nb0.6Ta0.4)O3 nanopowder was prepared by the sol–gel process from the AgNO3, Ta2O5 and Nb2O5, with help of K2CO3, avoiding use of strong corrosive acid or expensive niobium ethoxide and tantalum ethoxide. The results suggested that thermal
decomposition of the xerogel took place when the xerogel was heated at 450 °C. Well-crystallized single-phased powder was
obtained at low temperature about 680 °C. With the heat-treatment temperature increasing (680–1,100 °C), the intensity of
the diffraction peaks increased. The crystallite size determined by Scherer formula and the result suggested that higher temperature
lead to larger crystallite size. Moreover, the average grain size 30–50 nm was estimated by a field emission scanning electron
microscope. The influence of holding time on microstructures indicated that the homogeneous and small grains were obtained
at 800 °C for 2–4 h while larger ones for 8–16 h. 相似文献
8.
Jia-jia Ji Hui Sun Xiang-yu Mao Wei Wang Xiao-bing Chen 《Journal of Sol-Gel Science and Technology》2012,61(2):328-331
The Bi5FeTi3O15 (BFTO) films of layered structure have been fabricated on Pt/Ti/SiO2/Si substrates by the sol–gel method. The thermal decomposition behaviors of precursor powder were examined using thermo-gravimetric
and differential scanning calorimeters analysis. The optimal heat treatment process for BFTO films were determined to be low-temperature
drying at 200 °C for 4 min and high-temperature drying at 350 °C for 5 min followed by annealing at 740 °C for 60 min, which
led to the formation of compact films with uniform grains of ~300 nm. The structural, surface topography, ferroelectric and
magnetic properties of the films were investigated. The remnant polarization (2P
r) of BFTO thin films under an applied electric field of ~550 kV/cm are determined to be 67.5 μC/cm2
. Meanwhile, the weak ferromagnetic properties of the BFTO films were observed at room temperature. 相似文献
9.
N. P. Simonenko E. P. Simonenko V. G. Sevastyanov N. T. Kuznetsov 《Russian Journal of Inorganic Chemistry》2016,61(7):805-810
The synthesis of hydrolytically active heteroligand coordination compounds [M(C5H7O2)3?x(C5H11Oi)x] (M = Fe3+ and Y3+) using iron and yttrium acetylacetonates has been studied. The gel formation kinetics in solutions of these compounds upon hydrolysis and polycondensation has also been studied. Thin films of a solution of these precursors have been applied to polished sapphire substrates by dip coating technology. The crystallization of nanostructured yttrium iron garnet (Y3Fe5O12) films during heat treatment of xerogel coatings under various conditions has been studied. How the phase composition, microstructure, and particle size depend on the synthesis parameters has been recognized. 相似文献
10.
Zhanyong Wang Wenjun Fei Huichun Qian Min Jin Hui Shen Minglin Jin Jiayue Xu Weirong Zhang Qin Bai 《Journal of Sol-Gel Science and Technology》2012,61(2):289-295
CoFe2O4 ferrites were synthesized sol–gel with cobalt chloride, ferric chloride and citric acid as the main raw material. X-ray diffraction,
vibrating sample magnetometer and simultaneous thermal analysis were applied to character the structure and magnetic properties
of traditional and microwave calcined samples. The samples with pH 5 and molar ratio of citric acid to metal nitrate 1–1.2
showed the optimal structure and magnetic properties. Microwave calcination reduces the synthesis time from 2 h for conventional
calcination to 15–30 min. The saturation magnetization (σ
s
) for sample microwave-calcined at 550 °C for 30 min reaches to 75.89 emu/g, much higher than that of conventional-calcined
samples. 相似文献
11.
MgNb2O6 nanocrystalline powders have been synthesized at a low temperature by improved citrate sol–gel method in this paper. The
high quality solution of Nb5+ was prepared using Nb2O5 as the starting material. The crystal structure and microstructure of MgNb2O6 powders were characterized by XRD and SEM techniques, and the effects of preparation craft including pH value and the proportion
of citric acid to the niobium ions on the crystal structure and microstructure of powders were also investigated. XRD and
TG/DTA results show that the single phase of MgNb2O6 for synthesized powders can be obtained by calcining the precursor at 700 °C. SEM results indicate that the average particle
size of MgNb2O6 exhibits a significantly dependence on the pH values and the proportion of citric acid to the niobium ions, where it was
found that particle size of a 20 nm can be obtained for the MgNb2O6 powders by sol–gel process. 相似文献
12.
Nanocrystalline cubic fluorite/bixbyite CeO2 or α–Mn2O3 has been successfully synthesized by using methanol as a solvent via sol–gel method calcined at 400 °C. The obtained products
were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy
(SEM), Transmission electron microscopy (TEM), UV–vis absorption and Photoluminescence (PL) spectroscopy. TEM reveals that
the as-synthesized ultra-fine samples consist of elliptical/spherical and sheet-like morphology of crystalline particles of
8/30 nm, which are weakly aggregated. Optical absorbance spectra reveal that the absorption of ceria in the UV region originates
from the charge- transfer transition between the O2− (2p) and Ce4+ (4f) orbit in CeO2. However, α–Mn2O3 nanostructures with nearly pure band gap emission should be of importance for their applications as UV emitters. 相似文献
13.
14.
M. Kamal I. K. Battisha M. A. Salem A. M. S. El Nahrawy 《Journal of Sol-Gel Science and Technology》2011,58(2):507-517
A sol–gel process for producing monolithic silica–phosphate (SiO2–P2O5) system different concentrations of P2O5, starting with tetra-ethoxysilane TEOS, and triethyl-phosphate as sources of SiO2 and P2O5 was performed. The gels were heat-treated at temperatures ranging from 100 up to 900 °C. The structural and chemical analyses
of the samples were determined by using X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). It was
found from the XRD that the existence of phosphorus enhances the crystallization of silica gel, while the FTIR indicated the
main functional groups of silica–phosphate. It is important to study the effect of hydroxyl in silica–phosphate glass. The
results obtained are promising to use the prepared samples in a variety of applications, ranging from traditional application
such as lighting products) to the modern application (such as optical fibers. Optical studies were measured by using the spectrophotometer
in wavelength range 0.2–2.5 μm. The refractive index (n) was calculated for the prepared samples, it was found to be strongly affected by structural rearrangement resulting from
the elimination of the solvent and the Si–OH, Si–O–Si and Si–O–OH bonding by phosphate and aluminum and it increases by increasing
phosphate concentrations. The weight losses have investigated for prepared samples. 相似文献
15.
Xiaoyong Chen Wei Cai Chunlin Fu Huaqiang Chen Qiang Zhang 《Journal of Sol-Gel Science and Technology》2011,57(2):149-156
Barium zirconate titanate, Ba(Zr0.20Ti0.80)O3 (BZT) powders were prepared by sol–gel method. These powders were characterized by thermogravimetric and differential thermogravimetric
analyses (TG-DTA), X-ray diffraction (XRD) and microcopy electron transmission (TEM). The decomposition of the precursors
was monitored by TG-DTA. XRD patterns reveal that BZT powders heat treated at 800 °C present single phase with perovskite-type
cubic structure. TEM micrographs were employed to estimate the average particle size of the BZT powders (≈ 20 nm). The results
indicate that the particle size of the BZT powders increases with the increasing of the holding time and aging temperature.
The low aging temperature can reduce the agglomeration of the nanopowders. Three polyalcohols were employed as surfactants
in sol–gel method: butanol (BTOL), polyethylene glycol (PEG) and polyvinyl alcohol (PVA). It is noted that PEG has a better
effect on reducing agglomeration of BZT powders than that of the BTOL and PVA. 相似文献
16.
J. Ma C. Z. Chen D. G. Wang X. G. Meng J. Z. Shi 《Journal of Sol-Gel Science and Technology》2010,54(1):69-76
Two glasses of the CaO-MgO-P2O5-SiO2 system with different MgO contents (0 and 10 mol%, respectively) have been synthesized by sol–gel method. The degradation
of glass samples was evaluated through the weight loss in the tris-(hydroxymethyl)-aminomethane and hydrochloric acid (Tris–HCl)
buffer solution, and the in vitro bioactivity was assessed by determining the changes in surface morphology and composition
after soaking in a simulated body fluid. Formation of the apatite-like layer on glasses surface was studied by means of X-ray
diffraction, Fourier-transform infrared, scanning electron microscopy. Results indicate that, with the partial substitution
of MgO for CaO in glass composition, the glass degradation decrease and the formation of apatite-like layer is delayed. Furthermore,
it is observed that the glass bioactivity is relative to its dissolution, and the effects of MgO on glass degradability and
bioactivity may be attributed to the influence of ionic field strength and distinct bonding configuration of glass. 相似文献
17.
Neng Zhang Zhao-Chun Zhang Jian-Gang Zhou 《Journal of Sol-Gel Science and Technology》2011,58(2):355-359
Calcium stannate (CaSnO3) nanofibers were synthesized by electrospinning technique combined with a sol–gel process. The structure and morphology of
the as-prepared CaSnO3 nanofibers were characterized by X-ray diffraction and scanning electron microscopy, respectively. The samples had a band
gap of about 3.87 eV, which was estimated by UV–Vis diffuse reflectance spectroscopy. On the basis of the experiment results,
the composite fibers containing polymer and inorganic salt can be changed to pure CaSnO3 nanofibers only when they were sintered at an appropriate temperature. At the same time, a possible mechanism of the nanofibers
forming process was also proposed. 相似文献
18.
Preparation and characterization of TiO<Subscript>2</Subscript> sol–gel modified nanocomposite films
In this study, the role of TiO2 MT-150A loading in the polymeric sol was investigated for the synthesis of immobilized TiO2 nanocomposite films on glass substrate using the MT-150A nanoparticles-modified sol–gel method. The nanocomposite film properties
were examined using different material characterization techniques including X-ray diffraction, X-ray photoelectron spectroscopy,
field emission scanning electron microscopy, UV–Vis spectrophotometer, Scotch tape test and pencil hardness test. The hydrophilicity
of films during UV/Vis irradiation and storage in a dark place were evaluated by a contact angle analyzer. The MT-150A loading
had a significant effect on the amount of crystallite phases in the films. However, increasing the MT-150A loading in the
sol resulted in an increase in rutile phase content. In addition, increasing MT-150A loading in the sol yielded films with
higher hydrophilicity but a concentration of 10–30 g/L MT-150A in the sol was found as the maximum for obtaining films with
good adherence on the glass substrate. 相似文献
19.
Masoud Salavati-Niasari Masoud Farhadi-Khouzani Fatemeh Davar 《Journal of Sol-Gel Science and Technology》2009,50(3):321-327
Nanocrystalline films of magnetite have been prepared by a novel sol–gel route in which, a solution of iron (III) nitrate
dissolved in ethylene glycol was applied on glass substrates by spin coating. Coating solution showed Newtonian behaviour
and viscosity was found as 0.0215 Pa.s. Annealing temperature was selected between 291 and 350 °C by DTA analysis in order
to obtain magnetite films. In-plane grazing angle XRD and TEM studies showed that magnetite phase was present upon annealing
the films at 300 °C. The films had crack free surfaces and their thicknesses varied between ~10 and 200 nm. UV–Vis spectrum
results showed that transmittance of the films increases with decreasing annealing temperature and increasing spinning rate.
Up to 96% transmittance was observed between the wavelengths of 900–1,100 nm. Vibrating sample magnetometer measurements indicated
that magnetite thin films showed ferromagnetic behavior and the saturation magnetization value was found as ~35 emu/cm3. 相似文献
20.
Leticia M. Torres-Martínez Cecilia Sánchez-Trinidad Vicente Rodríguez-González Soo Wohn Lee Ricardo Gómez 《Research on Chemical Intermediates》2010,36(1):5-15
Indium-Na2Ti6O13 doped semiconductors were prepared by the sol–gel method using titanium and sodium alkoxides as precursors. The gelled samples
were annealed at 700 °C for 4, 6, and 8 h, and then characterized by X-ray diffraction (XRD), scanning electron microscopy
(SEM), energy-dispersive spectroscopy (EDS), and UV–Vis diffused reflectance spectroscopy (DRS). XRD patterns of the samples
show the formation of the Na2Ti6O13 phase, whose crystallinity depends on the annealing time. The band gap calculated from the UV–Vis Kubelka–Munk function report
similar values (3.2–3.4 eV) for all of the samples annealed at different times. SEM observations of the semiconductors showed
microfiber bundle morphologies of about 5 μm. Meanwhile, by EDS analysis, indium oxide highly homogeneously dispersed on the
hexatitanate surface was identified. The evaluation of the In-Na2Ti6O13 semiconductors in the 2,4-dichlorophenoxyacetic acid (2,4-D) photodecomposition using ultraviolet light (λ = 254 nm) irradiation show that the photoactivity of the solids depends on the annealing time applied to the samples. The
role of indium oxide is related to the indium oxide dispersed on the surface of the titanate diminishing the electron-hole
recombination rate. 相似文献