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1.
Haijun Zhang Faliang Li Quanli Jia Guotian Ye 《Journal of Sol-Gel Science and Technology》2008,46(2):217-222
Titanium carbide ultrafine powders were prepared from tetrabutyl titanate and sucrose by sol–gel and microwave carbothermal
reduction. The influences of reaction temperature and molar ratio of Ti to C on the synthesis of titanium carbide were studied.
The results show that excess amount of carbon plays a positive effect on the carbothermal reduction of TiO2 at low temperature. The inceptive carbothermal reduction temperature of TiO2 and formation of titanium oxycarbide was below 900 °C, and pure TiC can be prepared at 1,200 °C, which was considerably lower
compared to that by conventional carbothermal reduction using a mixture of TiO2 and carbon powders as raw materials. The morphology and particle size of synthesized TiC powder were examined by field emission-scanning
electron microscopy (FE-SEM) and the quantities of the phases of the powders were analyzed by Rietveld refinement method,
the particle sizes of the TiC powders synthesized at 1,300 °C distribute over 0.1–0.5 μm. 相似文献
2.
Effect of sol-gel preparation method on particle morphology in pure and nanocomposite PZT thin films
Double-scale composite lead zirconate titanate Pb(Zr0.52Ti0.48)O3 (PZT) thin films of 360 nm thickness were prepared by a modified composite sol-gel method. PZT films were deposited from
both the pure sol and the composite suspension on Pt/Al2O3 substrates by the spin-coating method and were sintered at 650°C. The composite suspension formed after ultrasonic mixing
of the PZT nanopowder and PZT sol at the powder/sol mass concentration 0.5 g mL−1. PZT nanopowder (≈ 40–70 nm) was prepared using the conventional sol-gel method and calcination at 500°C. Pure PZT sol was
prepared by a modified sol-gel method using a propan-1-ol/propane-1,2-diol mixture as a stabilizing solution. X-ray diffraction
(XRD) analysis indicated that the thin films possess a single perovskite phase after their sintering at 650°C. The results
of scanning electron microscope (SEM), energy-dispersive X-ray (EDX), atomic force microscopy (AFM), and transmission electron
microscopy (TEM) analyses confirmed that the roughness of double-scale composite PZT films (≈ 17 nm) was significantly lower
than that of PZT films prepared from pure sol (≈ 40 nm). The composite film consisted of nanosized PZT powder uniformly dispersed
in the PZT matrix. In the surface micrograph of the film derived from sol, large round perovskite particles (≈ 100 nm) composed
of small spherical individual nanoparticles (≈ 60 nm) were observed. The composite PZT film had a higher crystallinity degree
and smoother surface morphology with necklace clusters of nanopowder particles in the sol-gel matrix compared to the pure
PZT film. Microstructure of the composite PZT film can be characterized by a bimodal particle size distribution containing
spherical perovskite particles from added PZT nanopowder and round perovskite particles from the sol-matrix, (≈ 30–50 nm and
≈ 100–120 nm), respectively. Effect of the PZT film preparation method on the morphology of pure and composite PZT thin films
deposited on Pt/Al2O3 substrates was evaluated. 相似文献
3.
The composite powders 90 vol.% Al2O3–5 vol.% YAG–5 vol.% ZrO2 were produced by doping commercial alumina powders with zirconium and yttrium chloride aqueous solutions. Both a nanocrystalline
transition alumina and a pure α-phase powder were used as starting materials. The obtained materials were characterized by
DTA-TG, XRD and dilatometric analyses and compared to the respective biphasic systems developed by the same procedure. Pressureless
sintering at 1500 °C for 3 h was able to consolidate the doped powders in fully dense bodies, characterized by a very fine
and homogeneous dispersion of the second phases into the micronic alumina matrix. 相似文献
4.
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
5.
V. V. Bakovets S. A. Savintseva L. N. Trushnikova P. E. Plyusnin I. P. Dolgovesova T. D. Pivovarova I. V. Korol’kov 《Russian Journal of General Chemistry》2010,80(6):1115-1121
A processes of formation of nanostructured powders of nickel oxide by annealing in the temperature range of 200–700°C of the
nickel hydroxide obtained by the sol-gel method at 80°C from solutions of nickel nitrate by precipitation with alkali in the
presence of surfactant AF-12 (polyethylene oxide alkylphenyl ether) was investigated. The formation of nanostructured powders
of nickel oxide in the presence of a surfactant reduces the size of nanoparticles to 20–25 nm, which is 1.5 times smaller
than the particles obtained without a surfactant. The effective influence of surfactant on the particle size begins in the
temperature range of its decomposition and evaporation equal 350–400°C. 相似文献
6.
Nanocrystalline BaSnO3 with a primary particle size of 40–60 nm was prepared through hydrolysis of a barium tin isopropoxide and following crystallization.
The thermal decomposition, the crystallization and the microstructure of the obtained powders were investigated with the help
of TG-DTA, IR, XRD, HRSEM and HRTEM. The organic rest groups in the as-prepared powder decompose thermally at 350°C, which
is accompanied by the building of BaCO3 that disappear again at 600°C. The crystallization of BaSnO3 takes place at 500–600°C. Single-phase BaSnO3 powders have been obtained at a temperature as low as 600°C. The amorphous as-prepared powder shows a cluster structure.
Nucleation of BaSnO3 beginning at 350°C was observed under HRTEM, and the spherical nano-particles of BaSnO3 calcined at 760°C crystallize well and are strongly aggregated. The presented results indicate a heterogeneous nucleation
and growth mechanism by the formation of BaSnO3. 相似文献
7.
Esin Burunkaya Nadir Kiraz Ömer Kesmez H. Erdem Çamurlu Meltem Asiltürk Ertuğrul Arpaç 《Journal of Sol-Gel Science and Technology》2010,55(2):171-176
Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum
sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents.
Ratio of Al2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175–225 °C for 5 h. Ratios of alcohol, H2O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were
subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained
at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 °C. Particle size was determined as 3.2 ± 0.4 nm
from TEM examinations and as 1–2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus
they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO
powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential
to be utilized in the form of thin films for optical and electronic purposes. 相似文献
8.
Yingchao Han Xinyu Wang Shipu Li Xionghua Ma 《Journal of Sol-Gel Science and Technology》2009,49(1):125-129
Terbium doped calcium phosphate (Tb-doped CaP) nanocrystalline powders were synthesized by the citric acid sol–gel combustion
method. The phase composition, morphology and luminescent property of Tb-doped CaP nanocrystalline powders were characterized
by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrophotometer
and fluorescence microscopy. At 700 °C, Tb-doped CaP nanocrystalline powders are composed of HAP (main phase) and β-TCP (minor
phase) with Tb doping content of 0.5–4%. SEM and TEM observations show that the 4% Tb-doped CaP nanocrystalline powders are
about 50–150 nm spherical particles. The 4% Tb-doped CaP nanocrystalline powders exhibit the strongest emission at 548 nm
(λexcitation = 240 nm) and show strong green fluorescence under fluorescence microscopy. 相似文献
9.
Ge Yu Hailong Zhang Bo-Ping Zhang Jiamin Zhang 《Journal of Sol-Gel Science and Technology》2012,61(2):403-410
Sol–gel processing of Cu-particle-dispersed (K0.5Na0.5)NbO3 (Cu/KNN) thin films was studied in an attempt to develop a method producing piezoelectric composite films with good mechanical
performance. The Cu/KNN films were prepared via crystallization annealing at 650–750 °C for 1 min in air, followed by reduction
annealing at 400–500 °C for 1–2 h in a 5% H2 and 95% Ar gas mixture. The resultant composite films consisted of perovskite KNN, metallic Cu, and Cu4O3. This suggests that the decomposition of Cu sources takes two different ways in this study. The Cu/KNN composite films containing
Cu4O3 phases were produced by the crystallization annealing at 700 °C for 1 min followed by the reduction annealing at 500 °C for
1 h. Surface morphology observations reveal that these films have dense KNN matrix with a grain size of ~200 nm and uniformly
dispersed Cu or Cu4O3 particles with a size of <500 nm. 相似文献
10.
Bansi Lal Sasmita K. Patro Shivani Singh 《Journal of Sol-Gel Science and Technology》2010,56(3):340-344
Bismuth silicon oxide (Bi12SiO20, BSO) nano crystalline powder was prepared by sol–gel technique using bismuth nitrate and tetraethyl orthosilicate as starting
materials. The prepared samples were sintered at various temperatures (750 °C maximum) and characteristic sillenite single
cubic phase with crystallite size ~38 nm (calculated from room temperature powder XRD measurements) was realized at 750 °C
sintering temperature. SEM analysis showed that the powder contains the nano-sized particles with almost spherical morphology.
The observed frequencies in room temperature FTIR spectrum could be assigned to Bi–O, Si–O and Bi–O–Si bonds. The FWHM (full
width at half maximum) of the diffraction peaks decreased while the intensity of FTIR absorption lines increased with the
increase in the sintering temperature indicating better bond formation and crystallization. The thermograph of the samples
recorded in the temperature range 50–1,000 °C showed almost no weight loss after ~575 °C further confirmed the conclusion
arrived at from XRD and FTIR analysis. The samples sintered at 750 °C showed about 50% absorbance in 400–600 nm region which
was consistent with the pale yellow color of the sample. Broad blue emission centered ~478 nm was observed when excited by
350 nm radiation from a Xe-lamp. The intensity of this broad emission band increased while its FWHM decreased with the increase
in sintering temperature. Self-trapped excitons could be responsible for this emission. 相似文献
11.
I. V. Lisnevskaya I. A. Bobrova A. V. Petrova T. G. Lupeiko 《Russian Journal of Inorganic Chemistry》2012,57(4):474-477
A low-temperature method has been developed for preparing nickel ferrite doped with cobalt and copper (Ni0.9Co0.1Cu0.1Fe1.9O4 − δ). This method provides the target product at 170–200°C with nanosized particles. The role of ammonium nitrate in the considerable
reduction of ferrite synthesis temperature was studied. 相似文献
12.
Ronaldo Santos da Silva Maria Inês Basso Bernardi Antonio Carlos Hernandes 《Journal of Sol-Gel Science and Technology》2007,42(2):173-179
In this work, we have studied the influence of the pH on the synthesis and structural properties of the Ba0.77Ca0.23TiO3 nanopowders synthesized by a modified polymeric precursor method, in order to achieve non-agglomerated powders. Synthesis,
morphology, thermal reactions, crystallite and average particle size of the synthesized powders were investigated through
thermal analysis (DTA/TG), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and Infrared spectroscopy.
In summary, Ba0.77Ca0.23TiO3 nanopowders were synthesized for the first time at a relative low temperature (500 °C). It was also found that the alkalinity
and acidity of the solution presented a great influence on the powder properties. The best results were obtained from solutions
with pH = 8.5 and 11 whose nanopowders presented weakly agglomerate, with homogeneous particle size and a narrow size distribution
(30–40 nm). This behavior could be explained based on the FT-IR results in which it was possible to see the increased of the
chelation in higher pHs. 相似文献
13.
Taisuke Nakamura Masataka Shima Masahiro Yasukawa Kazushige Ueda 《Journal of Sol-Gel Science and Technology》2012,61(2):362-366
Pr3+ doped or Tb3+–Mg codoped CaSnO3 phosphor powder with perovskite structure was synthesized by the polymerized complex method. Powder samples crystallized
into the perovskite phase at approximately 600 °C, which is 400 °C lower than the crystallization temperature for the solid-state
reaction method. Uniform-sized powders with average particle sizes of 1–2 μm were obtained after heat treatment at 1,400 °C.
Although the samples heat-treated at 600 °C did not exhibit photoluminescence, white photoluminescence of Pr3+ doped CaSnO3 or green photoluminescence of Tb3+–Mg codoped CaSnO3 was observed from the sample heat-treated above 800 °C. The intensity of the photoluminescence increased with increase of
the heat-treatment temperature and reached a maximum for heat treatment at 1,400 °C. The maximum photoluminescence intensity
for the samples prepared by the polymerized complex method was larger than those prepared by solid-state reaction method,
which is probably due to the homogeneous mixing of the doped rare earth ions. 相似文献
14.
M. S. Bhuwaneswari L. Dimesso W. Jaegermann 《Journal of Sol-Gel Science and Technology》2010,56(3):320-326
Lithium intercalation materials are of special interest as cathodes in rechargeable batteries. An uncomplicated sol–gel process
has been used for the synthesis of Li–Co phosphates powders and, for the first time, of LiCoPO4 films. The powders were prepared from aqueous solutions, containing Li, Co and phosphate precursors to which acid citric
and ethylene glycol was added, during the drying process at 75 °C. The X-ray diffraction patterns of the prepared powders
confirmed the presence of LiCoPO4 with an olivine-like structure as main phase. The morphological investigations of the powder showed a platelet-like structure
with an average grain size of 0.75 μm. The films of LiCoPO4 were deposited onto ITO glass substrates with the combination of the dip-coating process under the same conditions. Finally,
the films were annealed in inert atmosphere at 300 °C. The morphological investigations reveal a smooth and homogeneous surface
of the prepared Li–Co phosphate films. The preliminary electrical investigation on the prepared LiCoPO4 films showed lithium ions electrochemical activity in the range 3.0–4.5 V. 相似文献
15.
C. K. Ghosh S. R. Popuri T. U. Mahesh K. K. Chattopadhyay 《Journal of Sol-Gel Science and Technology》2009,52(1):75-81
Nanocrystalline powders of CuAlO2 were synthesized through sol–gel method using nitrate-citrate route and also through solid state reaction method. We used
a new set of precursor materials for the synthesis of CuAlO2 through sol–gel route which were not reported in the past. A little lowering of the synthesis temperature (1,000 °C) was
observed in case of sol–gel process compared to the solid state reaction method (1,100 °C) and also at shorter time duration.
The particle size of the synthesized powders was determined through small angle X-ray scattering. It has been observed that
the particle size prepared by nitrate-citrate technique is less than the particle size prepared by the solid-state reaction
method. Chemical states of the atomic species were determined by X-ray photoelectron spectroscopy. The formation of phase
pure CuAlO2 were also confirmed by Fourier transformed infrared spectroscopy. A number of solvents were also used for finding the best
possible combinations for obtaining phase pure CuAlO2 at 1,000 °C and it was observed that only the combination of nitrate salts, citric acid and ethanol resulted phase pure CuAlO2. 相似文献
16.
Monica Ari Kimberly J. Miller Bojan A. Marinkovic Paula M. Jardim Roberto de Avillez Fernando Rizzo Mary Anne White 《Journal of Sol-Gel Science and Technology》2011,58(1):121-125
Aluminum molybdate was successfully synthesized using a simplified PVA assisted sol–gel method resulting in highly crystalline,
monophasic (monoclinic P21/a) samples. These materials could readily be obtained at temperatures of 600 and 700 °C after calcining for as little as
15–20 min. Scanning electron microscopy and X-ray powder diffraction indicated that even the sample calcined at 600 °C for
20 min was free of impurities and composed of submicron sized particles (~300 nm). Transmission electron microscopy was used
to confirm the monophasic character and submicron dimensions of the as-prepared powders. In addition to producing high quality
samples, it was also observed that the metal to PVA ratio used during this simplified synthesis, could be used as a control
parameter for tailoring the particle sizes of the final product. 相似文献
17.
Bimetallic Ni-Cu particles were synthesized from either suspensions of nickel carbonate and copper carbonate, and solutions of nickel nitrate and copper nitrate in ethylene glycol which acts both as solvent and reducing agent. The nature and composition of the powders depend on both the reaction temperature and time, and the reactants. Using the carbonates, bimetallic Ni-Cu powders composed of a nickel-rich and a copper-rich solid solution were obtained after 39 h at 140°C. Increasing the reaction temperature to 190°C gives a Ni-Cu powder composed of a copper-rich solid solution and nickel. Particles obtained under these conditions, however, are polydisperse. The nitrate solution gave bimetallic Ni-Cu particles with a narrow size distribution of about 140 nm after 4 h of reaction at 196°C. These particles are made of a copper core and a nickel shell. The mechanism of bimetallic particle formation is controlled by the solubility of the reactants, the formation of intermediate metal glycolates and Cu2O, and the required reduction temperature. 相似文献
18.
Robert Ianoş Ioan Lazău Cornelia Păcurariu 《Journal of Thermal Analysis and Calorimetry》2009,97(1):209-214
The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experimental results proved that β-alanine is a more suitable fuel for
LiNO3, whereas urea seems to be more adequate for Al(NO3)3. Based on the different metal nitrate/fuel mixture reactivity, nanocrystalline γ-LiAlO2 powders were prepared by solution combustion synthesis using a fuel mixture of urea and β-alanine. This fuel mixture yielded
single-phase nanocrystalline γ-LiAlO2 (32.6 nm) directly from the combustion reaction. The resulted powder had a specific surface area of 3.2 m2/g and no supplementary annealing was required. On the other hand, pure γ-LiAlO2 could not be obtained by using a single fuel (urea, β-alanine) unless annealing at 900 °C for 1 h was performed. 相似文献
19.
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
20.
James R. Heley David Jackson Peter F. James 《Journal of Sol-Gel Science and Technology》1997,8(1-3):177-181
Ultra fine silica powders were prepared by hydrolysis of SiCl4 using aqueous ammonia solution followed by supercritical drying. Using different methods of combining the SiCl4 and ammonia solution, to vary the initial and final pH of the solution, large silica powders surface areas (271–905 m2/g), fine average particle diameters (3.5–17) nm and low tapping densities (0.02–0.05 g/cm2) could be prepared. Powders with characteristics similar to pyrogenic silica, and with similar thermal stability at temperatures
up to 1000°C, could be produced. 相似文献