共查询到20条相似文献,搜索用时 15 毫秒
1.
Ibrahim H. Mutlu Maharram Z. Zarbaliyev Ferhat Aslan 《Journal of Sol-Gel Science and Technology》2009,50(3):271-274
In this study we describe the preparation of Ga2Se3 semiconductor compound thin films by sol–gel method for different crystal formation temperatures. The films were characterized
by X-ray diffraction analyses (XRD), UV–visible spectrometer, and scanning electron microscope (SEM). The XRD spectrum showed
that the formation of Ga2Se3 crystals were between 743 and 823 K. The thin film crystals that were formed at 773 K corresponded to the β phase and the
preferred crystal structure was monoclinic. The value of band gap from optical absorption spectra for the Ga2Se3 thin films was estimated to be about E
g ~ 2.56 eV. The thickness of the one-coat Ga2Se3 thin films, which was measured by a Spectroscopic Ellipsometer, was about ~200 nm. The average grain sizes of scattered particles
were within the limits between 200 and 500 nm. 相似文献
2.
Marcela Stoia Mircea Stefanescu Thomas Dippong Oana Stefanescu Paul Barvinschi 《Journal of Sol-Gel Science and Technology》2010,54(1):49-56
The paper presents a study on the preparation of Co2SiO4/SiO2 nanocomposites by a new modified sol–gel method. We have prepared gels starting from tetraethylorthosilicate (Si(OC2H5)4), cobalt nitrate Co(NO3)2·6H2O and some diols: ethylene glycol (C2H6O2), 1,2propanediol (C3H8O2) and 1,3propanediol (C3H8O2), for a final composition: 30% CoO/70% SiO2. During the heating of the gels at 140 °C, a redox reaction takes place between NO3
− ions and diol with formation of some carboxylate anions. These carboxylate anions react with the Co(II) ions to form coordination
compounds embedded in silica matrix, as evidenced by FT-IR spectrometry and thermal analysis. These Co(II) coordinative compounds
thermally decompose in the range 250–300 °C to the corresponding oxides: CoO and/or Co3O4 inside the matrices pores. When CoO results, it reacts with SiO2 at low temperature leading to Co2SiO4, which crystallizes at 700 °C. XRD patterns of the samples annealed at temperatures lower than 700 °C were characteristic
to amorphous phases. The samples annealed at temperatures ≥700 °C, contain Co2SiO4 (olivine) as unique crystalline phase inside the amorphous silica matrix, according to XRD patterns. As evidenced by TEM
images, Co2SiO4 nanoparticles are homogenously dispersed inside the silica matrix. 相似文献
3.
This study describes the In2S3 semiconductor thin film coating on glass substrate by sol–gel method. The In2S3 thin film samples were prepared and examined by the X-ray diffraction (XRD), the UV–visible optical absorption and transmission
study, and the Scanning Electron Microscope (SEM) image analyses. The XRD analysis results show that the In2S3 semiconductor thin films prepared by sol–gel method is formed at T~360–520 °C temperature interval. Band gap energy and optical
absorption spectrum analysis of the In2S3 thin films reveal that Eg~2.51 eV for the In2S3 thin films. According to the EDX result the film was In-rich with the In/S = 1.42 ratio. The thickness of prepared In2S3 layer is about 400 nm. 相似文献
4.
5.
Nursen Avci Philippe F. Smet Hilde Poelman Nigel Van de Velde Klaartje De Buysser Isabel Van Driessche Dirk Poelman 《Journal of Sol-Gel Science and Technology》2009,52(3):424-431
Stable TiO2 sols were prepared using two non-aqueous sol–gel processes with titanium n-butoxide and titanium isopropoxide, respectively. Crystallization and phase transitions of powders and thin films were studied
by ex situ and in situ X-ray diffraction. For both methods, TiO2 began to crystallize around 320 °C in air. Using helium instead of air during heat treatment slowed down the crystallization
and substoichiometric powders were formed. TiO2 thin films were obtained by spin coating. The morphology of the films was evaluated using scanning electron microscopy. The
films were homogeneous and transparent in the visible range. The effect of the heating atmosphere and the type of substrate
was investigated. 相似文献
6.
Petr Brázda Daniel Nižňanský Jean-Luc Rehspringer Jana Poltierová Vejpravová 《Journal of Sol-Gel Science and Technology》2009,51(1):78-83
ε-Fe2O3/SiO2 nanocomposite was prepared by novel solgel method using single precursor for both nanoparticles and matrix. This method allows to prepare the samples free of α-Fe2O3 with 40% of Fe2O3 in SiO2. Nanoparticles of 12 nm diameter were obtained by annealing at 1,000 °C. The samples were characterized by powder X-ray diffraction and transmission electron microscopy. Mössbauer spectroscopy identified ε-Fe2O3 as the only magnetically ordered phase at room temperature. Magnetic measurements revealed progressive necking of hysteresis loops measured at 300 and 2 K. In both cases the intrinsic coercivity reaches only 0.25 T. Measurements up to 14 T shows monotonous decreasing trend of saturated magnetization with increasing temperature. 相似文献
7.
Z. Zhuang X. P. Wang A. H. Sun Y. Li Q. F. Fang 《Journal of Sol-Gel Science and Technology》2008,48(3):315-321
La2Mo2O9 films were successfully synthesized on silicon (100) and poly-alumina substrates via modified sol–gel method with inorganic
salts of La(NO3)3 and (NH4)6Mo7O24 as precursors. Pure La2Mo2O9 phase was confirmed by XRD if the annealing temperature was higher than 500 °C. Energy dispersive spectrometry (EDS) of TEM
revealed that the molar ratio of La to Mo was nearly 1:1. Field-emission SEM characterization showed that the films were dense,
crack-free and uniform. The grain size of the films ranged from 30 to 400 nm depending upon the calcination temperature and
duration time. The roughness calculated from AFM topography varied in the range between 10 and 35 nm. The thickness of the
films was more than 200 nm for single-layered films. The electrical conductivity of the films reaches 0.06 S/cm at 600 °C
that was almost more than one order of magnitude higher than that of the corresponding bulk material. 相似文献
8.
Shih-Yuan Lin Chih-Ming Wang Kuo-Sheng Kao Ying-Chung Chen Chan-Chih Liu 《Journal of Sol-Gel Science and Technology》2010,53(1):51-58
Molybdenum trioxide (MoO3) films were deposited on ITO/Glass substrates by the sol–gel method using a spin-coating technique and heat treated at various
temperatures under different ambient atmosphere. Effects of the process parameters on the electrochromic properties of MoO3 films were studied using cyclic voltammetry (CV) in a propylene carbonate (PC) non-aqueous solution containing 1 M lithium
perchlorate (LiClO4). Electrochromic MoO3 film on lithium intercalation was investigated by in-situ transmittance measurement during the CV process. The MoO3 films showed reversible recharge ability on Li+/e− intercalation/deintercalation. Experimental results revealed that the heat-treatment temperature, the ambient atmosphere,
and the thickness will have the string influence on the electrochromic properties of MoO3 thin films. X-ray diffraction (XRD) results show that the amorphous MoO3 films can be obtained with the heat-treatment temperature below 300 °C in O2 ambient atmosphere. The optimum electrochromic MoO3 film, with a thickness of 130 nm, exhibits a maximum transmittance variation (ΔT%) of 30.9%, an optical density change (ΔOD) of 0.213, an intercalation charge (Q) of 8.47 mC/cm2, an insertion coefficient x in Li
x
MoO3 was 0.21 and a coloration efficiency (η) of 25.1 cm2/C between the colored and bleached states at a wavelength (λ) of 550 nm. 相似文献
9.
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
10.
Fredrik Söderlind Linnéa Selegård Per Nordblad Kajsa Uvdal Per-Olov Käll 《Journal of Sol-Gel Science and Technology》2009,49(2):253-259
Thin films of the perovskite and garnet structured gadolinium ferrites GdFeO3 and Gd3Fe5O12 have been synthesized by a sol–gel method, based on stoichiometric mixtures of acetyl acetone chelated Gd3+ and Fe3+ dissolved in 2-methoxy ethanol. After spin coating onto Si wafers, and heating in air at 700 °C for 20 h, neatly grown essentially
single phase films were obtained. From X-ray photoelectron spectroscopy an iron deficiency is observed in the uppermost layer
of both films, implying that the crystallites preferably end in planes rich in Gd and O but not in Fe. The films were also
characterized by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, and magnetic measurements. 相似文献
11.
CeO2/TiO2 nanocomposite was synthesized by particulate sol–gel method. The X-ray diffractogram shows the presence of cubic CeO2 and anatase TiO2 in the composite. The high resolution scanning electron micrographs reveal the nanoparticulate nature of the prepared composite. The composite absorbs UV light and exhibits near-band gap emission corresponding to TiO2 and deep level emission due to crystal defects. The Nyquist plot displays two semicircular arcs indicating the material heterogeneity. The physicochemical characteristics of the synthesized nanocomposite are in favour of its application as an ingredient of sunscreen formulations; under UV light the photocatalytic activity of CeO2/TiO2 composite, tested through the degradation of rhodamine B, is very much less than that by pristine anatase TiO2. Reduced adsorption of moisture by the nanocomposite is a possible reason for the observed very low photocatalytic activity. 相似文献
12.
A. Kamyabi-Gol S. M. Zebarjad S. A. Sajjadi 《Journal of Sol-Gel Science and Technology》2009,51(1):92-101
The present work deals with the synthesis of Ni–SiO2–Al2O3 nanocomposites fabricated by embedding nickel oxide particles, obtained from hexahydrated nickel nitrate [Ni(NO3)2 · 6H2O], in matrixes with different molar percents of Silica/Alumina, through sol–gel method based on hydrolysis and condensation
of tetraethylorthosilicate (TEOS) and Aluminum Isopropoxide [Al(OC3H7)3] alkoxides. Due to the various factors, e.g., pH, EtOH/TEOS/H2O ratio, Si/Ni ratio etc., influencing the nickel grain size of the nanocomposites, Taguchi robust design method of system
optimization was used to determine the percent of contribution (%ρ) of each factor. The nanocomposites were reduced in a flow
of hydrogen and nitrogen gas at 700 °C for half an hour. The nickel grain size in the nanocomposites was determined by utilizing
Scherrer`s method and XRD patterns. The smallest nickel grain size obtained from the Taguchi orthogonal array was about 24 nm,
later confirmed by TEM observations. After optimization of the controlling factors, a nickel grain size of 15.4 nm was obtained.
It was found that the SiO2/Al2O3 molar ratio of the matrix had the most influence on the nickel grain size (29.22%) and the Water/TEOS molar ratio stood in
second place (21.44%). It was illustrated that the starting temperature of the aluminum isopropoxide had the least influence
on the nickel grain size. 相似文献
13.
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
14.
K. P. Lopes L. S. Cavalcante A. Z. Simões R. F. Gonçalves M. T. Escote J. A. Varela E. Longo E. R. Leite 《Journal of Sol-Gel Science and Technology》2008,45(2):151-155
NiTiO3 (NTO) nanoparticles encapsulated with SiO2 were prepared by the sol–gel method resulting on core-shell structure. Changes on isoelectric point as a function of silica
were evaluated by means of zeta potential. The NTO nanoparticles heat treated at 600°C were characterized by X-ray diffraction,
transmission electron microscopy (TEM) and energy dispersive X-ray analysis. TEM observations showed that the mean size of
NTO is in the range of 2.5–42.5 nm while the thickness of SiO2 shell attained 1.5–3.5 nm approximately. 相似文献
15.
Yang Ren Gaoyang Zhao Chenxi Zhang Yuanqing Chen 《Journal of Sol-Gel Science and Technology》2012,61(3):565-569
CuAlO2 thin films were deposited on quartz substrates by sol–gel process using copper acetate monohydrate and aluminum nitrate nanohydrate
as starting materials and isopropyl alcohol as solvent. The influence of annealing temperature on the film structure and the
phase evolution of CuAlO2 films were investigated, so as to obtain CuAlO2 films with superior performance. The phase compositions of the films were dependent on the annealing temperature. The films
annealed at temperatures below 400 °C were amorphous while those annealed above 400 °C were polycrystalline. The phases of
CuO and CuAl2O4 appeared gradually with the increase of annealing temperature. When the heat treatment temperature was elevated to 900 °C,
the uniform and dense films with single phase of CuAlO2 were obtained, with a resistivity of 15 Ωcm. The transmittance of the 310 nm-thick CuAlO2 film is 79% at 780 nm and the direct optical band gap is 3.43 eV. 相似文献
16.
Ömer Kesmez Nadir Kiraz Esin Burunkaya H. Erdem Çamurlu Meltem Asiltürk Ertuğrul Arpaç 《Journal of Sol-Gel Science and Technology》2010,56(2):167-176
SiO2 sols were prepared by hydrolysis and condensation reactions of tetraethyl orthosilicate through a one step acid or a two step acid + base catalysis process, in the presence of nitric acid and four different base catalyzers, namely trimethylamine, triethylamine, tripropylamine and tributylamine. Hydrolysis of TEOS was followed by FT-IR analyses. Particle size distributions of the sols were evaluated after predetermined durations in 1–22 days. Particle growth was seen to be faster in amine catalyzed systems than in one step acid catalyzed system. The highest rate of growth was in triethylamine catalyzed system. Glass substrates were dip coated with the prepared SiO2 sols. Effect of sol aging duration on film thickness and on light transmittance properties of the films was investigated with respect to type of base catalyst. Thicknesses of the films which were measured to be in the range of 100–400 nm, were seen to increase with aging duration of the sols. Triethylamine catalyzed system presented the highest film thickness. Films obtained from one step acid catalyzed system presented an increase of 4.8%; whereas acid + base catalyzed films provided an increase in the light transmittance of 5.7% in the first 4 days of aging. Surfaces of films were examined by FESEM and AFM. The antireflective character of the films was verified by diffuse reflectance analyses. 相似文献
17.
18.
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
19.
Xin Zhang Xiaogang Li Junsheng Wu Renchun Yang Limin Tian Zhihua Zhang 《Journal of Sol-Gel Science and Technology》2009,51(1):1-3
Mesoporous TiO2 with a high specific surface area was prepared from titanium sulfate solution in a simple sol–gel route, where formamide
was used as pH adjusting agent. TiO2 had a high resistance to phase transformation, and maintained monophasic anatase after calcinating at 600 °C. The highest
specific surface area achieved on the prepared samples is 231.90 m2 g−1 after calcinating at 450 °C. 相似文献
20.
Chiwon Kang Jung-Hyun Park Dongna Shen Hosang Ahn Minseo Park Dong-Joo Kim 《Journal of Sol-Gel Science and Technology》2011,58(1):85-90
(K0.5 Na0.5)NbO3 (KNN) perovskite materials have been developed as a promising lead-free piezoelectric material for environmentally benign
piezoelectric devices. KNN films with about 320 nm thickness were fabricated on Pt(111)/SiO2/Si(100) substrates by a sol–gel method from stoichiometric and A-site ion excess precursor solutions. Two different annealing
methods were also used to investigate the crystallographic evolution of the films. A layer-by-layer annealing process results
in highly (001) oriented KNN from the annealing temperature of 550 °C, while the final annealing method leads to weaker crystalline
peaks with a random orientation. The KNN films from the K and Na excess precursor solutions show similar crystallization behavior.
However, the ferroelectric hysteresis loops of the films were greatly improved by compensating for an A-site vacancy. In particular,
the KNN films from K-excess precursor solutions show better ferroelectric properties compared to the films prepared from Na
excess solutions. 相似文献