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1.
《Microporous and mesoporous materials》2007,98(1-3):189-199
Mesoporous silica materials have been synthesized through sol–gel reaction using inexpensive sodium silicate as source of silica and low cost hydroxy carboxylic acid compounds as templates/pore forming agents. The material measured surface area of 1014 m2/g, pore diameter of 65 Å and pore volume of 1.4 cc/g when parameters like time and temperature of synthesis along with mole ratio of TA/SiO2 were optimized. Here TA stands for tartaric acid. Carbonization of sucrose inside the pores of above silica material at 900 °C followed by removal of silica framework using aqueous ethanoic solution of NaOH gave rise to mesoporous carbon material. The resulting materials were characterized by N2-sorption, FTIR spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, thermal analysis and cyclic voltammetry. Three dimensional interconnecting wormhole channel arrangement of mesoporous silica template leads to mesoporous carbon replica with surface area of 1200 m2/g. X-ray photoelectron spectroscopic study (XPS) of the mesoporous carbon material shows the concentration of carbon atom in the range of 97–98% with 1–2% oxygen and negligible amount of silica. The electrochemical double layer capacitance behavior of carbon material with the specific capacitance value of 88.0 F/g at the scan rate of 1 mV/s appears to be promising. 相似文献
2.
《Ceramics International》2016,42(7):7974-7979
In this paper forsterite (Mg2SiO4) nanopowder with particle size in the range of 33 and 112 nm was synthesized by a combination of sol–gel and ball milling methods. Magnesium nitrate and silica were used as the sources of magnesium and silicon in the forsterite nanopowder. Thermogravimetry (TG) analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and dynamic light scattering (DLS) techniques were utilized to characterize the synthesized powders. Single-phase nanocrystalline forsterite powder with mean crystallite size of about 16 nm was obtained from sol–gel method with subsequent ball milling for 5 h and heat treatment at 750 °C for 1 h. A combination of sol–gel and mechanical activation led to the formation of more homogeneous powder and subsequently lower sintering temperature to produce forsterite powder. In vitro biological studies were performed by immersing the forsterite samples in simulated body fluid (SBF). The results showed that nanostructure forsterite is bioactive and possessed apatite formation ability. 相似文献
3.
We successfully fabricated uniform SnO2–SiO2–Pt composite nanofibres (NFs) by using a co-electrospinning technique, in which we set up two coaxial capillaries. Morphology control of NFs was investigated, along with their structural properties and chemical compositions. Furthermore, to systematically investigate the morphological changes in SnO2–SiO2–Pt composite NFs, the relative weight ratios of the Sn precursor to the Si precursor including the 4 wt% Pt precursor were controlled at 3:1, 1:1, and 1:3. To demonstrate the formation mechanism of the composite NFs, the precursor positions of the shell section and the core section in co-electrospinning were reversed. The resultant composite NFs were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). These results showed that in the case of the optimum weight ratio (1:1) of the Sn precursor in the shell section to the Si precursor including the 4 wt% Pt precursor in the core section, SnO2 and Pt nanoparticles were uniformly grown on SiO2 NFs, implying the successful formation of uniform SnO2–SiO2–Pt composite NFs. 相似文献
4.
《Journal of the European Ceramic Society》2007,27(1):185-189
High brightness Y2SiO5:Ce phosphor powders with spherical shape and fine size were synthesized by melting salt assisted sol–gel method (MS&Sol–Gel). Commercial tetraethyl orthosilicate was used as the silica source and rare earth oxides were used as rare earth source. The prepared Y2SiO5:Ce powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser particle sizer, and fluorescentometer techniques. Y2SiO5:Ce powders were obtained at significantly lower temperature than that by conventional techniques. When sintered at 1200 °C for 2 h with 5 wt.% LiF and 2 wt.% KH2PO4 as fluxes, particles with spherical shape and narrow particle distribution could be obtained. Moreover, the grain size of the powders prepared through this process was in the range of 2–7 μm, strongly depending on the thermal treatments and the species of fluxes. PL intensity of the prepared Y2SiO5:Ce phosphor using 5 wt.% LiF and 2 wt.% KH2PO4 as fluxes was similar to that of commercial product. 相似文献
5.
《Ceramics International》2007,33(6):915-918
Nano-sized (Sn0.25,Ti0.75)O2 photocatalysts were successfully synthesized by a molten salt (MS) method at 260 °C for 2 h, where a homogeneous precipitate containing titanium and tin cations as a precursor. The synthesized powders were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis, respectively. The results show that the products are composed of homogeneously spherical particles with an average size of ca.10 nm, and have better UV absorption and visible light response when the reaction temperature is increased to 400 °C. 相似文献
6.
L. Mancic K. Marinkovic B.A. Marinkovic M. Dramicanin O. Milosevic 《Journal of the European Ceramic Society》2010,30(2):577-582
Cerium-doped yttrium aluminum garnet (YAG:Ce3+) powder phosphor is synthesized via spray pyrolysis of polymeric precursor solution obtained by dissolving the corresponding nitrates in ethylenediaminetetraacetic acid (EDTA). Ultrasonically generated aerosol droplets are decomposed at 600 °C in argon atmosphere. Following the initial attempt in providing pure YAG:Ce3+ phase generation the particles were additionally thermally treated for 3 h in air at 1000 and 1100 °C. The powder morphology is followed with scanning electron microscopy (SEM), while inner particle structure is analysed by analytical and high-resolution transmission electron microscopy (TEM). Phase identification is performed by X-ray powder diffraction (XRPD) based on which a structural refinement through Rietveld method was done. The spherical submicronic particles have grained sub-structure comprising clustered garnet monocrystals sized below 100 nm. The YAG:Ce3+ emission shows wide peak in the range 470–600 nm with the maximum near 520 nm. 相似文献
7.
《Ceramics International》2016,42(9):10599-10607
Pure and chromium doped titanium dioxide (TiO2) thin films at different atomic percentages (0.5%, 1.3% and 2.9%) have been elaborated on ITO/Glass substrates by sol–gel and spin–coating methods using titanium (IV) isopropoxide as a precursor. The surface morphology of films was investigated by scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM), the structure was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission microscopy (HRTEM). SEM and HRTEM show homogenous and polycrystalline films. XRD patterns indicate a phase transition from anatase to anatase-rutile leading to expand the absorption band of TiO2 molecules around 520 cm−1 in FTIR spectra. The optical constants such as the refractive index (n), the extinction coefficient (K) and the band gap (Eg) as well as the film thickness are determined using spectroscopic ellipsometry technique and Fourouhi–Blommer dispersion model. Results show three major changes; (i) the thickness of pure TiO2 layer is 54 nm, which linearly decreases when the layer is doped with chromium and reaches 33 nm for a doping concentration of 2.9%, (ii) the band gap energy (Eg) is also linearly reduced from 3.24 eV to 2.80 eV when the Cr-doping agent increases, and, (iii) a phase transition from anatase to anatase-rutile is observed causing an increase in values of n(λ) for wavelength greater than 350 nm. 相似文献
8.
《Journal of Industrial and Engineering Chemistry》2014,20(1):113-117
CaO is an important material because of its application as catalyst and effective chemisorbents for toxic gases. In this research CaO nanoparticles were prepared via direct thermal decomposition method using Ca(OH)2 as a wet chemically synthesized precursor. Nanocrystalline particles of Ca(OH)2 have been obtained by adding 1 and 2 M NaOH aqueous solutions to 0.5 M CaCl2·2H2O aqueous solutions at 80 °C. The precursor [Ca(OH)2] was calcined in N2 atmosphere at 650 °C for 1 h. Samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared spectrum (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunaure–Emett–Teller (BET). SEM images showed that CaO nano-particles were nearly spherical in morphology. TEM images illustrated that produced CaO nano-particles had the mean particle size of 91 and 94 nm for 1 and 2 M NaOH concentration, respectively. As a result, this method could be used for production of CaO nano-particles on large-scale as a cheap and convenient way, without using any surfactant, organic medium or complicated equipment. 相似文献
9.
《Carbon》2013
Hybrid silica–carbon nanotube (CNT) particles with a radial symmetry were produced by the growth of nanotubes onto spherical, mesoporous silica gel particles using the floating catalyst chemical vapour deposition (FC-CVD) method. Characterisation of the hybrid particles, using electron microscopy, Raman spectroscopy and thermogravimetry showed the geometry and porosity of the silica particles to influence the alignment and density of the CNTs produced. CNT growth initiated in the pores of the gel particles and three hours of CVD growth were required to get extensive surface coverage. In the early stages of growth, the reactants diffused inside the mesoporous silica and consequently the CNTs grew mainly within the silica gel rather than on the surface. Some indication of catalyst templating was observed within the smaller (<10 nm) pores, but this templating did not result in aligned CNTs. Composite films of hybrid silica–CNT particles in poly(vinyl alcohol) were cast and their impedance measured. An electrical percolation threshold of 0.62 wt.% was found for the hybrid particles, of which 0.20 wt.% were CNTs. 相似文献
10.
《Journal of the European Ceramic Society》1999,19(16):2731-2737
The nitridation of elemental silicon powder at 900–1475 °C was studied by X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), XRD, thermal analysis and 29Si MAS NMR. An initial mass gain of about 12% at 1250–1300 °C corresponds to the formation of a product layer about 0·2 μm thick (assuming spherical particles). XPS and XAES show that in this temperature range, the surface atomic ratio of N/Si increases and the ratio O/Si decreases as the surface layer is converted to Si2N2O. XRD shows that above 1300 °C the Si is rapidly converted to a mixture of α- and β-Si3N4, the latter predominating >1400 °C. In this temperature range there are only slight changes in the composition of the surface material, which at the higher temperatures regains a small amount of an oxidised surface layer. By contrast, in the interval 1400–1475 °C, the 29Si MAS NMR chemical shift of the elemental Si changes progressively from about −80 ppm to −70 ppm, in tandem with the growth of the Si3N4 resonance at about −48 ppm. Possible reasons for this previously unreported change in the Si chemical shift are discussed. © 相似文献
11.
《Ceramics International》2016,42(13):14862-14866
TiO2 was prepared by detonating a slurry explosive made of Ti precursor, ammonium nitrate, cyclotrimethylenetrinitramine (RDX), and polystyrene (EPS). X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and UV–vis diffuse reflection spectroscopy revealed that the sample was composed of mixed crystals of rutile and anatase TiO2 with irregular spherical shapes and 10 nm particle size. The minimum energy gap of the sample was 2.9 eV. An ideal TiO2 explosive was prepared from a precursor/ammonium nitrate/RDX ratio of 1:1:0.6 and 2 g of EPS as a density modifier. 相似文献
12.
《Ceramics International》2015,41(6):7421-7428
The goal of this study was to demonstrate that sol–gel processing route is suitable for the fabrication of calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHA) thin films on Si substrate by spin-coating technique. The substrate was spin-coated by precursor sol solution 1, 5, 15 and 30 times. The samples were annealed after each spin-coating procedure at 1000 °C for 5 h in air. In the sol–gel process ethylendiamintetraacetic acid and 1,2-ethandiol, and triethanolamine and polyvinyl alcohol were used as complexing agents and as gel network forming agents, respectively. The coatings were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman spectroscopies, profilometry and the contact angle measurements (CAM). It was demonstrated, that properties of calcium hydroxyapatite thin films depend on spinning and annealing times. 相似文献
13.
B.T. Raut M.A. Chougule Shashwati Sen R.C. Pawar C.S. Lee V.B. Patil 《Ceramics International》2012,38(5):3999-4007
Polyaniline–CdS nanocomposites have been synthesized by spin coating technique. The nanocrystalline CdS powder of particle size 40–50 nm was synthesized by sol–gel technique and the polyaniline was synthesized by chemical oxidative polymerization of aniline. The composite films were characterized by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy and Four probe method. The results were compared with corresponding data on pure polyaniline films. The intensity of diffraction peaks for PANi–CdS composites is lower than that for CdS. The conductivity measurement shows that molecular chain constitution of polyaniline is the most important carrier in polyaniline–CdS nano composite. The optical studies showed that variation in band gap of polyaniline (3.40 eV) to 2.54 eV CdS which is attributed to the interaction of CdS nanoparticles with PANi molecular chains. 相似文献
14.
《Journal of Industrial and Engineering Chemistry》2014,20(4):1819-1824
Zirconia fine particles were prepared by ultrasonic spray pyrolysis (USP) and employed as a substrate for titanium/titania coating by ultrasonochemistry. The effects of several process factors on the characteristics of the prepared particles were investigated and the particles were then characterized by various techniques. This substrate was coated with various titanium concentrations (0.025–0.1 M) for two ultrasonication time periods (30 min, 2 h) by sonochemistry, and finally calcined at 1100 °C. Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size analysis (PSA), Fourier transformation infrared spectroscopy (FT-IR) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) comprised the techniques used to characterize them. The particles were prepared in a monodispersed spherical form with no interior cavity; their average size was shown to be 0.62 μm before calcination and 2.57 μm after calcination. The titania surface coating acted to partially stabilize the particles to a tetragonal phase. Based on the analytical results, the optimum conditions for preparing the particles were shown to be 7.5 wt% of titania as an initial solution concentration and 0.5 h of coating time. 相似文献
15.
S. Vivekanandhan M. Venkateswarlu D. Carnahan M. Misra A.K. Mohanty N. Satyanarayana 《Ceramics International》2013,39(4):4105-4111
Surface modification of nanocrystalline NiFe2O4 spinel particles with amorphous SiO2 by the sol–gel process at 350 °C was demonstrated. Amorphous phase of the SiO2 layer was evaluated by X-ray diffraction technique. Structural coordination of the pristine and SiO2 coated NiFe2O4 particles as investigated by employing FTIR analysis. Thickness of the SiO2 layer was investigated through transmission electron microscopy and it was identified to be ~10–23 nm over nanocrystalline NiFe2O4 particles. The magnetic behavior of pristine and surface modified NiFe2O4 particles were investigated using vibrating sample magnetometer (VSM). Magnetic studies showed the retention of magnetic property of surface modified NiFe2O4 particles with the reduced saturation magnetization and coercivity compared to the pristine NiFe2O4 particles, which is respectively due to the lower fraction of the magnetic component and the formation of interfacial structure. 相似文献
16.
Cr-incorporated diamond-like carbon (Cr-DLC) films were deposited on AZ31 magnesium alloy as protective coatings by a hybrid beams deposition system, which consists of a DC magnetron sputtering of Cr target (99.99%) and a linear ion source (LIS) supplied with CH4 precursor gas. The Cr concentration (from 2.34 to 31.5 at.%) in the films was controlled by varying the flow ratio of Ar/CH4. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the microstructure and composition of Cr-DLC films systematically. An electrochemical system and a ball-on-disk tribotester were applied to test the corrosion and tribological properties of the film on the AZ31 substrate, respectively. At low Cr doping (2.34 at.%), the film mainly exhibited the feature of amorphous carbon, while at high doping (31.5 at.%), chromium carbide crystalline phase occurred in the amorphous carbon matrix of the film. In this study, all the prepared Cr-DLC films showed higher adhesion to AZ31 than the DLC film. Especially for the film with low Cr doping (2.34 at.%), it owned the lowest internal stress and the highest adhesion to substrate among all the films. Furthermore, this film could also improve the wear resistance of magnesium alloy effectively. But, none of the films could improve the corrosion resistance of the magnesium alloy in 3.5 wt.% NaCl solution due to the existence of through-thickness defects in the films. 相似文献
17.
《Applied catalysis. B, Environmental》2009,85(3-4):457-467
Two series of Sr- or Ce-doped La1−xMxCrO3 (x = 0.0, 0.1, 0.2 and 0.3) catalysts were prepared by thermal decomposition of amorphous citrate precursors followed by annealing at 800 °C in air atmosphere. The effect of Ce and Sr on the morphological/structural properties of LaCrO3 was investigated by means of thermogravimetric/differential thermal analysis (TG/DTA) of the precursors decomposition under air, X-ray diffraction (XRD), electron paramagnetic resonance (EPR), transmission electron microscopy–X-ray energy dispersive spectroscopy (TEM–XEDS), SBET determination, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques. The characterization results are employed to explain catalytic activity results for C3H6 combustion. It is shown that the lanthanum chromite perovskite structure is obtained upon thermal treatment of the sol–gel derived precursors at T > ca. 800 °C. The presence of the dopant generally induces the formation of segregated oxide phases in the samples calcined at 800 °C although some introduction of the Sr in the perovskite structure is inferred from EPR measurements. The oxidation activity becomes maximised upon formation of such doped perovskite structure. 相似文献
18.
Mohammad Hossein Habibi Reza Sheibani 《Journal of Industrial and Engineering Chemistry》2013,19(1):161-165
Silver-doped zinc oxide (SDZO) films have been grown on glass substrate by a novel combination of sol–gel and photochemical deposition processes (SGPD). The effect of sintering on structural, electrical and optical properties was investigated. The films were characterized by UV–vis absorption spectroscopy (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The result of X-ray photoelectron spectroscopy (XPS) revealed that the binding energy of Ag 3d5/2 for SDZO shifts remarkably to the lower binding energy compared to the pure metallic Ag due to the interaction between silver and zinc oxide. The XRD spectra of the SDZO films indicate that silver was incorporated in the hexagonal crystal structure of zinc oxide. SEM micrographs show the uniform distribution of spherical grains of about 73 nm grain size for the pure zinc oxide thin films. The results indicated that silver doping photochemical deposition was a feasible method to tune the optical properties of zinc oxide nanostructures. SDZO films coated on glass were applied for the photodegradation of mercaptan in water. SDZO films were applied for degradation of mercaptobenzoxazole which reduced the mercaptan concentration to more than 98%. 相似文献
19.
Lead zirconate titanate nanoparticles (PZT-NPs) were synthesized by a modified sol–gel method and were calcinated at temperatures of 600, 650 and 700 °C. Fourier transform infrared (FTIR), powder X-ray diffraction (XRD) and thermal analysis (TGA/DTA), indicate that single-phase perovskite PZT-NPs are obtained after heat treatment at a temperature of 650 °C. The TEM results obtained from the PZT-NPs confirm that the morphology of the PZT nanoparticles is spherical, with an average diameter size of 17 nm. We also investigated the crystallite development in the nanostructured PZT by X-ray peak broadening analysis. The individual contribution of many small crystallite sizes and lattice strains to the peak broadening in the PZT nanoparticles prepared at different temperatures were studied using Williamson–Hall (W–H) analysis in the range of 2θ = 15–80°. 相似文献
20.
The adsorption of toluene was tested with MCM-41 and mesoporous silica materials (S-MCM) synthesized from waste solar panel. X-ray powder diffraction (XRD), nitrogen adsorption–desorption analysis, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were applied to characterize the prepared samples. In addition, the adsorption capacities of MCM-41 and S-MCM were almost the same which was observed according to the breakthrough experiments. The adsorption capacity of toluene in S-MCM was 57, 104, 200 and 277 mg g− 1 for initial toluene concentrations of 250 to 1500 ppm respectively. The effects of the operation parameters, such as contact time and initial concentration on adsorption performance, were also tested in this study. 相似文献