共查询到20条相似文献,搜索用时 31 毫秒
1.
H. C. Vasconcelos 《Journal of Sol-Gel Science and Technology》2010,55(1):126-133
SiO2-TiO2-PO2,5 (STP) and SiO2-TiO2-AlO1,5 (STA) glasses were prepared by sol-gel processing. Their infrared absorption spectra (IR), differential thermal analysis
curves (DTA) and X-ray diffraction patterns (XRD) have been recorded. In the SiO2-TiO2 system, the chemical homogeneity of the sol-gel glass could be evaluated by the relative concentration of Si-O-Ti heterocondensation
comparing to Si-O-Si homocondensation. For the STA system, a gradual decrease of the Si-O-Ti/Si-O-Si band ratio (based on
IR spectra) with the addition of Al2O3 is observed, with the simultaneous formation of Si-O-Al and Ti-O-Al bounds, i.e Al3
+ ions are dissolved in the SiO2-TiO2 glass matrix and do not promote glass-in-glass phase-separation in the composition range of 0–15 mol% AlO1.5. In the STP system, on the other hand, P=O bond IR stretch in the ternary glasses indicates that P=O free PO2O2/2
− tetrahedra are formed, rather than the double bonded POO3/2 tetrahedra that usually occur in binary SiO2-P2O5 glasses. It can be concluded that SiO2-TiO2-P2O5 glass separates into a SiO2-rich phase and a TiO2(P2O5)-rich phase. During heat-treatment in STA system only anatase precipitates, even at T ~ 1,000 °C, while in for STP, anatase (TiO2) or (TiO)2P2O7 (TOP) crystals precipitate at ~600 °C, depending on the P2O5 concentration. The major crystal phase, cristobalite, precipitated at ~1,000 °C and at ~1,200 °C, the P-containing phase
melts. 相似文献
2.
A. L. Zharnyl’skaya V. V. Vol’khin H. Reuther 《Russian Journal of Applied Chemistry》2009,82(8):1364-1369
Samples of a precursor for an aluminum oxide ceramics reinforced with zirconium oxide were synthesized by hydrolysis of various
aluminum salts in the presence of a ZrO2 sol under conditions of urea decomposition at 90°C and pH < 4 maintained, with hydrolysis products deposited onto the surface
of ZrO2 sol particles. It was found that the nature of a salt anion affects the interaction of hydrolysis products of the aluminum
cation with the surface of ZrO2 sol particles. The structure of products formed in thermal treatment of samples of a precursor for Al2O3-ZrO2 (T = 1250°C) was characterized by X-ray phase analysis and scanning electron microscopy. The phase transition temperatures of
the oxides Al2O3 and ZrO2 contained in the precursor were estimated using the results of thermal analysis of the samples in the temperature range 20–1300°C. 相似文献
3.
Li Chen Haixia Shen Zhen Lu Cang Feng Su Chen Yanru Wang 《Colloid and polymer science》2007,285(13):1515-1520
TiO2–SiO2 composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO2–SiO2 composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO2–SiO2) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO2–SiO2 composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO2–SiO2 composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO2–SiO2 core surface via surface functionalized reaction. The particle size of TiO2–SiO2 composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and
Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid
films. The average particle size of the TiO2–SiO2 composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO2–SiO2 composite nanoparticles are well dispersed in the PU matrix. 相似文献
4.
Vinícius D. Araújo Waldir Avansi Elaine C. Paris Lauro J. Q. Maia Maria I. B. Bernardi 《Journal of Sol-Gel Science and Technology》2011,59(3):488-494
Pb2CrO5 nanoparticles were embedded in an amorphous SiO2 matrix by the sol–gel process. The pH and heat treatment effects were evaluated in terms of structural, microstructural and
optical properties from Pb2CrO5/SiO2 compounds. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy
(EDS), and diffuse reflectance techniques were employed. Kubelka–Munk theory was used to calculate diffuse reflectance spectra
that were compared to the experimental results. Finally, colorimetric coordinates of the Pb2CrO5/SiO2 compounds were shown and discussed. In general, an acid pH initially dissolves Pb2CrO5 nanoparticles and following heat treatment at 600 °C crystallized into PbCrO4 composition with grain size around 6 nm in SiO2 matrix. No Pb2CrO5 solubilization was observed for basic pH. These nanoparticles were incorporated in silica matrix showing a variety of color
ranging from yellow to orange. 相似文献
5.
Zhan Jie Wang Hirokazu Usuki Toshihide Kumagai Hiroyuki Kokawa 《Journal of Sol-Gel Science and Technology》2007,42(3):375-379
(La0.7Sr0.3)MnO3 thin films were deposited on SiO2/Si substrates by a metal-organic decomposition (MOD) method, and then Pb(Zr0.52Ti0.48)O3 (PZT) thin films were grown on (La0.7Sr0.3)MnO3-coated SiO2/Si substrates by a sol-gel method. The effects of annealing temperature on the crystalline phases, microstructures and electrical
properties of the PZT films were investigated. X-ray diffraction analysis results indicated that the PZT films with a perovskite
single phase could be obtained by annealing at 650°C. The dielectric constant and the remnant polarization of the PZT films
increased with increasing annealing temperature. The remnant polarization and the coercive field of the films annealed at
650°C were 18.3 μC/cm2 and 35.5 kV/cm, respectively, whereas the dielectric constant and loss value measured at 1 kHz were approximately 1100 and
0.81, respectively. 相似文献
6.
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
7.
Magnetic Co3O4 nanoparticles were prepared by using microporous regenerated cellulose films as sacrificial scaffolds. The cellulose macromolecules
and the porous structure of the films made them used as spatially confined reacting sites where Co(OH)2 nanoparticles could be synthesized in situ. When the cellulose matrix was removed by sintering at 500 °C, Co3O4 nanoparticles were obtained. XRD and XPS indicated that the prepared nanoparticles were pure Co3O4 without any impurity. TEM and SEM images revealed that the particle size of the nanoparticles was smaller than 100 nm. The
nanoparticles had weak ferromagnetic properties at 25 °C. Furthermore, the pronounced quantum confinement effects of the synthesized
nanoparticles have been observed, the optical bandgap energies determined were about 1.92 ~ 2.12 and 2.74 ~ 2.76 eV for O2− → Co3+ and O2− → Co2+ charge-transfer processes, respectively. Furthermore, the resulted Co3O4 nanoparticles behaved stable electrochemical performance with promising applications in the electrode for lithium ion battery. 相似文献
8.
The phase transition at T
p (~109 °C) of RbH2PO4 and its composite with SiO2 has been investigated by thermal analysis here. In the case of neat RbH2PO4, there is a linear relationship between endothermic peak temperature (T
m) and square root of heating rate (Φ
1/2), from which the onset temperature of phase transition can be determined. Besides, Kissinger method and another calculation
method were employed to obtain the activation energy of phase transition. The detailed deduction process was presented in
this paper, and the estimated activation energies are E
1 ≈ 126.3 kJ/mol and E
2 ≈ 129.2 kJ/mol, respectively. On the other hand, the heterogeneous doping of RbH2PO4 with SiO2 as dopant facilitates its proton conduction and leads to the disappearance of jump in conductivity at T
p. The heats of transition in the composites decrease gradually with increasing the molar fraction of SiO2 additives. In the cooling process, a new and broad exothermic peak appeared between ~95 and ~110 °C, and its intensity also
changes with the SiO2 amount. These phenomena might be related to the formation of amorphous phase of RbH2PO4 on the surface of SiO2 particles due to the strong interface interaction. 相似文献
9.
Takeshi Miki Kaori Nishizawa Eiji Watanabe Hiroshi Taoda 《Research on Chemical Intermediates》2009,35(3):257-262
To obtain porous TiO2 film, the precursor sol was prepared by hydrolysis of Ti isopropoxide and then complexed with trehalose dihydrate. The porous
TiO2 film was fabricated by the dip-coating technique on glass substrates using this solution. The TiO2 film was calcined at 500 °C. The maximum thickness of the film from one-run dip-coating was ca. 740 nm. The film was composed
of nanosized particle and pores. The porosity of the TiO2 film was increased by addition of trehalose dihydrate to the sol. The porous TiO2 films were calcined at different temperatures. The effects of calcination temperature on the microstructure of the porous
TiO2 film were investigated. The porous film prepared from sol containing trehalose still kept the porous structure after calcination
at 950 °C. The phase transition temperature of the film from anatase to rutile was shifted from 650 to 700 °C by addition
of trehalose to the sol. 相似文献
10.
Xiu-Bin Ren Hai-Yan Lu Hai-Bo Lin Ya-Nan Liu Yan Xing 《Russian Journal of Electrochemistry》2010,46(1):77-80
WO3 films have been prepared onto IrO2-coated Ti substrate by electro-deposition, and as-deposited and annealed films have been characterized by using Raman spectroscopy.
It was found that the asdeposited film consists of orthorhombic WO3 · H2O phase, which transforms to amorphous WO3 by annealing at 250°C and to monoclinic phase by annealing at and above 350°C. All electrochemical experiments were carried
on Ti/IrO2/WO3 annealed at 450°C. The open-circuit potential could change significantly due to the hydration of the coating film. However
this process is fairly slow. Reproducible voltammograms could be obtained quickly, further revealing high electrochemical
stability of the Ti/IrO2/WO3 electrode. And the shapes of CV show the approximate rectangular mirror image, showing the typical characteristic of capacitive
behavior. The specific capacitance obtained at a scan rate of 50 mV s−1 is 46 F g−1. 相似文献
11.
The metal-ferroelectric-semiconductor (MFS) heterostructure has been fabricated using Bi3.25La0.75Ti3O12 (BLT) as a ferroelectric layer by sol-gel processing. The effect of annealing temperature on phase formation and electrical
characteristics of Ag/BLT/p-Si heterostructure were investigated. The BLT thin films annealed at from 500°C to 650°C are polycrystalline,
with no pyrochlore or other second phases. The C-V curves of Ag/BLT/p-Si heterostructure annealed at 600°C show a clockwise C-V ferroelectric hysteresis loops and obtain good electrical properties with low current density of below 2×10−8 A/cm2 within ±4 V, a memory window of over 0.7 V for a thickness of 400 nm BLT films. The memory window enlarges and the current
density reduces with the increase of annealing temperature, but a annealing temperature over 600°C is disadvantageous for
good electrical properties. 相似文献
12.
E. Kraleva M. L. Saladino R. Matassa E. Caponetti S. Enzo A. Spojakina 《Journal of Structural Chemistry》2011,52(2):330-339
Pure titania, zirconia, and mixed oxides (3–37 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by
Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen
adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the
presence of 3–13 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature
increase above 700°C. The mixed oxide with 37 mol.% of ZrO2 treated at 550°C shows a new single amorphous phase with a surface area of the nanoparticles double with respect to the other
crystalline samples and the formed srilankite structure (at 700°C). The anatase phase is not observed in the sample containing
37 mol.% of ZrO2. The treatment at 700°C causes the formation of the srilankite (Ti0.63Zr0.37Ox) phase. 相似文献
13.
Charles Y. Cummings Susan J. Stott Michael J. Bonné Karen J. Edler Pauline M. King Roger J. Mortimer Frank Marken 《Journal of Solid State Electrochemistry》2008,12(12):1541-1548
The formation of variable-thickness CeO2 nanoparticle mesoporous films from a colloidal nanoparticle solution (approximately 1–3-nm-diameter CeO2) is demonstrated using a layer-by-layer deposition process with small organic binder molecules such as cyclohexanehexacarboxylate
and phytate. Film growth is characterised by scanning and transmission electron microscopies, X-ray scattering and quartz
crystal microbalance techniques. The surface electrochemistry of CeO2 films before and after calcination at 500 °C in air is investigated. A well-defined Ce(IV/III) redox process confined to
the oxide surface is observed. Beyond a threshold potential, a new phosphate phase, presumably CePO4, is formed during electrochemical reduction of CeO2 in aqueous phosphate buffer solution. The voltammetric signal is sensitive to (1) thermal pre-treatment, (2) film thickness,
(3) phosphate concentration and (4) pH. The reversible ‘underpotential reduction’ of CeO2 is demonstrated at potentials positive of the threshold. A transition occurs from the reversible ‘underpotential region’
in which no phosphate phase is formed to the irreversible ‘overpotential region’ in which the formation of the cerium(III)
phosphate phase is observed. The experimental results are rationalised based on surface reactivity and nucleation effects. 相似文献
14.
K. G. Khatmullina G. R. Baimuratova V. A. Lesnichaya N. I. Shuvalova O. V. Yarmolenko 《Polymer Science Series A》2018,60(2):222-228
Nanocomposite polymer electrolytes based on the system poly(vinylidene fluoride-co-hexafluoropropylene)–liquid electrolyte 1 mol/L LiBF4 in gamma-butyrolactone which is modified by introducing up to 10 wt % of SiO2 nanopowder (an average particle size of 7 nm) are synthesized and characterized. The introduction of SiO2 nanoparticles worsens the elasticity of films but increases their fracture stress to 24 MPa. The conductivity of the nanocomposite electrolytes containing SiO2 nanoparticles is higher than that without SiO2 and attains 3.7 mS/cm at 20°C for the electrolyte containing 1.25 wt % SiO2. Upon the introduction of SiO2 nanoparticles, the electrochemical stability of electrolytes grows by 0.50–0.85 V and attains 6.7 V relative to Li/Li+. 相似文献
15.
Jun Liu Wenping Geng Xiujian Chou Wendong Zhang 《Journal of Sol-Gel Science and Technology》2012,62(3):414-418
(Pb, La)(Zr, Ti)O3 antiferroelectric thick films with (100)-preferred orientation were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates via a sol–gel method. The electric-field-induced antiferroelectric (AFE) to ferroelectric (FE) phase transition
characteristics were studied by C (capacitance)–E (electric field) measurements at different temperature. The films were in
AFE state under 0 kV/cm below 122 °C, and the switching field values decreased, with increasing temperature. The films were
in FE state between 122 and 135 °C, and when the temperature above 135 °C, the films were in PE state. The temperature-dependent
dielectric parameters were deconvoluted using a Gaussian fit multi-peaks showed that two typical phase transitions were discovered.
The first peak is the AFE-to-FE phase transition and the second peak is the FE-to-PE phase transition which has been verified
by C–E tests. 相似文献
16.
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
17.
Betul Akkopru Akgun Nathan P. Mellott Caner Durucan 《Journal of Sol-Gel Science and Technology》2012,62(2):240-251
Silver containing silica (Ag–SiO2) thin films with and without aluminum (Al) were prepared on soda-lime-silica glass by spin coating of aqueous sols. The coating
sol was formed through mixing tetraethyl orthosilicate [Si(OC2H5)4]/ethanol solution with aqueous silver nitrate (AgNO3) and aluminum nitrate nonahydrate [(AlNO3)3·9H2O] solutions. The deposited films were calcined in air at 100, 300 and 500 °C for 2 h and characterized using x-ray diffraction,
UV-visible and x-ray photoelectron spectroscopy. The effect of Al incorporation and calcination treatment on microstructure
and durability of the films, and chemical/physical state of silver in the silica thin film have been reported. The bactericidal
activity of the films was also determined against Staphylococcus aureus via disk diffusion assay studies before and after chemical durability tests. The investigations revealed that the optical,
bactericidal properties and chemical durability of Ag–SiO2 films can be improved by Al addition. The Al-modified Ag–SiO2 thin films do not exhibit any coloring after calcination in the range of 100–500 °C, illustrating that silver is incorporated
within the silica gel network in ionic form (Ag+). Al incorporation also improved the overall durability and antibacterial endurance of Ag–SiO2 thin films. 相似文献
18.
Ba(Ti1−x
Sn
x
)O3 (x = 0.10 or 0.15) thin films were deposited on Si(100) and Pt(111)/TiO
x
/SiO2/Si(100) substrates via sol–gel spin-coating. Crack-free thin films could be obtained by single-step deposition, where the
thickness was about 0.46 and 0.29 μm at 1000 and 2000 rpm, respectively. Circular delaminated parts 100 μm in diameter, however,
tended to appear in thicker films deposited at 1000 rpm. On both kinds of substrates, the films were crystallized between
500 and 600 °C, where the perovskite phase emerged as the primary phase, and the formation of single-phase perovskite was
basically achieved between 700–800 °C. The films deposited on Pt(111)/TiO
x
/SiO2/Si(100) substrates, however, tended to have small SnO2 and BaCO3 diffraction peaks, which decreased with increasing spinning rate. The dielectric properties were evaluated on the films deposited
on Pt(111)/TiO
x
/SiO2/Si(100) substrates at 2000 rpm. The films prepared by single-step depositions had dielectric constants of 350 and 230, and
dielectric loss of 0.30 and 0.10 at x = 0.1 and 0.15, respectively. The films prepared by two time deposition had dielectric constants of 450 and 250, and dielectric
loss of 0.21 and 0.19 at x = 0.10 and 0.15, respectively. 相似文献
19.
Chen-Chia Chou Shen-Da Tsai Wen-Hsiang Tu Yu-En Yeh-Liu Hsien-Lung Tsai 《Journal of Sol-Gel Science and Technology》2007,42(3):315-322
Fabrication of ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thick films on a Pt/Ti/SiO2/Si substrate using powder-mixing sol-gel spin coating and continuous wave CO2 laser annealing technique to treat the specimens with at a relatively low temperature was investigated in the present work.
PZT fine powders were prepared by drying and pyrolysis of sol-gel solutions and calcined at temperatures from 400 to 750°C.
After fine powder-containing sol-gel solutions were spin-coated on a substrate and pyrolyzed, CO2 laser annealing was carried out to heat treat the specimens. The results show that laser annealing provides an extremely
efficient way to crystallize the materials, but an amorphous phase may also form in the case of overheating. Thicker films
absorb laser energy more effectively and therefore melt at shorter periods, implying a significant volume effect. A film with
thickness of 1 μm shows cracks and rough surface morphology and it was difficult to obtain acceptable electrical properties,
indicating importance of controlling interfacial stress and choosing appropriate size of the mixing powders. On the other
hand, a thick film of 5 μm annealed at 100 W/cm2 for 15 s exhibits excellent properties (P
r = 36.1 μC/cm2, E
c = 19.66 kV/cm). Films of 10 μm form a melting zone at the surface and a non-crystallized bottom layer easily at an energy
density of 100 W/cm2, showing poor electrical properties. Besides, porosity and electrical properties of thick films can be controlled using appropriate
processing parameters, suggesting that CO2 laser annealing of modified sol-gel films is suitable for fabricating films of low dielectric constants and high crystallinity. 相似文献
20.
P. M. Silenko A. N. Shlapak T. V. Tomila A. I. Bykov A. V. Ragulya 《Theoretical and Experimental Chemistry》2011,47(1):9-13
The effect of the production temperature on the morphology and structure of Si3N4 nanofibers was investigated. It was shown that nanofibers produced in the temperature range of 1340–1360°C are amorphous
while those produced at 1380°C and above are monocrystalline. Apart from the principal phase (α-Si3N4) the imide Si2N2NH was also found in the reaction products. 相似文献