共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Ma C.Z. Chen D.G. Wang J.Z. Shi 《Materials science & engineering. C, Materials for biological applications》2010,30(6):886-890
The partial substitution of MgO for CaO in the ternary SiO2–CaO–P2O5 glass system was conducted by the sol–gel method and a comparison of the textural and structural properties was reported. The textural properties (specific surface area and pore size distribution) were obtained by N2-adsorption measurement and the glasses structure was elucidated by Fourier transform infrared spectroscopy. It is observed that, in general, all synthesized glasses show high specific surface area and present porous nature in mesopore region. The presence of MgO in glass composition has little influence on its textural properties, however, with increasing MgO concentration the frequency of Si–O(s,asym) group shifts towards lower energy and the absorbance intensity ratio of Si–O–NBO(Q3)/Si–O–Si(s,sym)(Q4) declines, indicating the structure modification of MgO in glass composition. 相似文献
2.
《Current Opinion in Solid State & Materials Science》2003,7(2):151-157
Since the launching of the photonic bandgap concept in 1987, the development of corresponding structures has expanded very rapidly, in particular two-dimensional semiconductor-based structures. In the case of sol–gel derived materials, the main emphasis for the past year has been on one-dimensional multilayer stacks and, in particular, on three-dimensional structures of the opal and inverse opal type. 相似文献
3.
Ill Yong Kim Chikara Ohtsuki Aisling Coughlan Lana Placek Anthony W. Wren Mark R. Towler 《Journal of materials science. Materials in medicine》2013,24(12):2677-2682
Glass ionomer cements (GICs) are composed of an acid degradable glass, polyacrylic acid and water. Sol–gel processing to prepare the glass phase has certain advantages, such as the ability to employ lower synthesis temperatures than melt quenching and glasses that are reported to have higher purity. A previous study reported the effects of glass synthesis route on GIC fabrication. However, in that study, the sol–gel derived glass exhibited a reduced concentration of cations. This study investigates increasing the cation content of a sol–gel derived glass, 12CaO·4SrO·36ZnO·48SiO2 (molar ratio) by heating before aging to reduce dissolution of cations. This glass was prepared by both sol–gel and melt-quenched routes. GICs were subsequently prepared using both glasses. The resultant cement based on the sol–gel derived glass had a shorter working time than the cement based on the melt-quenched one. Contrary to this, setting time was considerably longer for the cement based on the sol–gel derived glass than for the cement based on the melt-quenched one. The cements based on the sol–gel derived glass were stronger in both compression and biaxial flexure than the cements prepared from the melt-quenched glass. The differences in setting and mechanical properties were associated with both cation content in the glass phase and the different surface area of the resultant cements. 相似文献
4.
Catauro M Raucci MG De Gaetano F Marotta A 《Journal of materials science. Materials in medicine》2004,15(7):831-837
The antibacterial effect of addition of silver oxide to Na2O x CaO x 2SiO2 glass have been studied. Silver containing and silver free Na2O x CaO x 2SiO2 glasses have been prepared by sol-gel synthesis using tetramethil orthosilicate, sodium ethoxide, calcium nitrate tetrahydrate and silver nitrate as starting materials and methyl ethyl ketone as solvent. The gel was examined by differential thermal analysis, thermo gravimetric analysis, FTIR spectroscopy and X-ray diffraction analysis. Antibacterial and bioactive tests on gel glass powders, obtained after a heat treatment of 2 h at 600 degrees C of the dried gel, were carried out. High antimicrobial effects of samples against Escherichia coli and Streptococcus mutans were found. FTIR measurements and SEM micrographs have ascertained the formation of a hydroxyapatite layer on the surface of samples soaked in a simulated body fluid for different times. 相似文献
5.
The fabrication of ceramic composites based on a mullite matrix uniaxially reinforced with either high strength carbon or Nicalon-SiC continuous fibres is described. Sols of high solids contents of up to 40 vol% were prepared using colloidal silica sol with either -alumina powder or colloidal boehmite as reactants for the preparation of the mullite matrix, 3Al2O3·2SiO2. Single-stage infiltration was used for the preparation of prepregs for laminating into composites. The composites were consolidated by uniaxially hot-pressing at 1300 or 1550°C, depending on the matrix precursors and the final phases in the matrix. Highly densified composites with fibre volume fractions of 32–60% were obtained and the microstructures characterised by mercury porosimetry, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. 相似文献
6.
A. W. Wren A. Coughlan K. E. Smale S. T. Misture B. P. Mahon O. M. Clarkin M. R. Towler 《Journal of materials science. Materials in medicine》2012,23(12):2881-2891
A series of titanium (Ti) based glasses were formulated (0.62 SiO2?C0.14 Na2O?C0.24 CaO, with 0.05?mol% TiO2 substitutions for SiO2) to develop glass/ceramic scaffolds for bone augmentation. Glasses were initially characterised using X-ray diffraction (XRD) and particle size analysis, where the starting materials were amorphous with 4.5???m particles. Hot stage microscopy and high temperature XRD were used to determine the sintering temperature (~700?°C) and any crystalline phases present in this region (Na2Ca3Si6O16, combeite and quartz). Hardness testing revealed that the Ti-free control (ScC??2.4?GPa) had a significantly lower hardness than the Ti-containing materials (Sc1 and Sc2 ~6.6?GPa). Optical microscopy determined pore sizes ranging from 544 to 955???m. X-ray microtomography calculated porosity from 87 to 93?% and surface area measurements ranging from 2.5 to 3.3?SA/mm3. Cytotoxicity testing (using mesenchymal stem cells) revealed that all materials encouraged cell proliferation, particularly the higher Ti-containing scaffolds over 24?C72?h. 相似文献
7.
8.
《Thin solid films》2002,402(1-2):65-70
Lanthanum and niobium-doped lead zirconate titanate, Pb(Zr,Ti)O3, (PZT) thin films were prepared on Pt/Ti/SiO2/Si substrates by sol–gel processing. Films have a Zr/Ti ratio of 52:48 and tetragonal perovskite phase structure. The influence of donor dopants on the morphology, texture and defects of PZT films was studied using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, breakdown field strength and fatigue. Donor doping of PZT films results in increased breakdown field strength and improved fatigue properties. These originate from (i) the reduction of texture in the [111] and increase in the texture in [100]; (ii) lower porosity, smaller grain size and smoother surfaces; (iii) granular grain structure; and (iv) reduction in the oxygen vacancy concentration in the films. 相似文献
9.
《Materials Characterization》2003,50(2-3):95-99
Silica embedded with transition metals exhibits adequate properties for applications in catalysis, sensors and optics. Cobalt–silica (Co–SiO2) nanocomposites were prepared by the sol–gel method and thermally treated at 700, 900, 1100 and 1250 °C. Characterization of the samples was performed by XRD and BET nitrogen adsorption. The performance of the nanocomposites was investigated by catalysis reactions of oxidation. These catalysts were found to be recyclable showing a catalytic activity even after a third recovering. The results indicate that thermal treatment of sol–gel nanocomposites at temperatures higher than 900 °C is essential for the preparation of active heterogeneous catalysts. 相似文献
10.
Miki Inada Akira Nishinosono Kai Kamada Naoya Enomoto Junichi Hojo 《Journal of Materials Science》2008,43(7):2362-2366
Spherical mesoporous SiO2 and SiO2–TiO2 particles were synthesized by sol–gel method using W/O emulsion under microwave irradiation. In SiO2 system, W/O emulsion was prepared by mixing partially hydrolyzed Si(OC2H5)4 aqueous solution including C18TAC as template with n-hexane solution including polyglycerol polyricinalate as emulsifier. In SiO2–TiO2 system, Ti(OC2H5)4 capped by acetylacetone was added to the aqueous phase. In both cases, spherical products were synthesized by heating of
W/O emulsion for 30 min under microwave irradiation. The specific surface area and pore size of spherical products were 800 m2/g and 1.6 nm, respectively, which indicates that the spherical products are mesoporous. These results suggest that sol–gel
reaction in water phase proceeds rapidly because microwave quickly and selectively heats up the aqueous solution. 相似文献
11.
Kyung-Jun Hwang Jae-Wook Lee Wang-Geun Shim Hee Dong Jang Se-Il Lee Seung-Joon Yoo 《Advanced Powder Technology》2012,23(3):414-418
Titanium dioxide (TiO2) powders were synthesized by using TiO2 colloidal sol prepared from titanium-tetraisopropoxide (TTIP) and used as a starting material by applying the sol–gel method. The effect of aging times and temperatures on physical and chemical properties of TiO2 sol particles was systematically investigated. The results showed that the crystallinity and average particle size of TiO2 can be successfully controlled by adjusting the aging time and temperature. The samples after calcination of TiO2 powders were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and nitrogen adsorption measurements. In addition, the photocatalytic activity of synthesized TiO2 powders was evaluated by studying the degradation of 10 ppm aqueous methylene blue dye under 32 W high pressure mercury vapor lamp with 100 mg of TiO2 powders. The highest photocatalytic activity was observed in TiO2 powder synthesized at 90 °C for 0 h attributed to the presence of anatase and rutile phases in an 80:20 ratio. 相似文献
12.
E. Hatzistavrou X. Chatzistavrou L. Papadopoulou N. Kantiranis E. Kontonasaki A.R. Boccaccini K.M. Paraskevopoulos 《Materials science & engineering. C, Materials for biological applications》2010,30(3):497-502
The fabrication and characterization of sol–gel derived hydroxyapatite–calcium oxide (HAp–CaO) material is investigated focusing on the effect of the addition of a bioactive glass on the material bioactive behaviour through the fabrication of a novel HAp–CaO (70 wt.%)–bioactive glass (30 wt.%) composite material. The bioactive behaviour of the materials was assessed by immersion studies in Simulated Body Fluid (SBF) and the alterations of the materials surfaces after soaking periods in SBF were characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). A brittle and weakly crystalline carbonate hydroxyapatite (HCAp) layer was found to develop on the surface of all samples, few hours after immersion in SBF, confirming the high bioactivity of the material. Alterations of the morphology of the developed HCAp layer, which led to a more compact structure, were observed on the surface of composite samples after 7 days of immersion in SBF. The presence of the CaO phase seems to accelerate the formation of HCAp, while the bioactive glass affects both the morphology and cohesion of the developed layer. 相似文献
13.
Shr-Nan Bai Shich-Chuan Wu 《Journal of Materials Science: Materials in Electronics》2011,22(4):339-344
Zinc oxide (ZnO) nanowires with various morphologies are synthesized by the hydrothermal method on silicon substrates coated
with ZnO thin films. The ZnO films are used as the seed layer and are prepared using the sol–gel technique. Experimental results
demonstrate that the synthesis of ZnO nanowires is dependent on the crystalline properties of the ZnO seed-layer films. Sol
concentration is the controlled parameter for the preparation of ZnO seed-layer films in this study. The ZnO films are found
to have the hexagonal wurtzite structure with highly preferred growth along the c-axis at suitable sol concentrations. The vertically aligned ZnO nanowire arrays on the substrates are believed to be the
result of the epitaxial growth of the ZnO seed layer. Scanning electron microscopy shows that nanowires with uniform distribution
in length, diameter, and density are obtained. X-ray diffraction patterns clearly reveal that the ZnO nanowires are primarily
grown along the c-axis direction. Transmission electron microscopy and selected-area electron diffraction measurements show that the nanowires
have good crystalline properties. The well-aligned and high surface areas of the ZnO nanowires make them a potential candidate
for applications in solar cells, field emission devices, and ultra-sensitive gas sensors. 相似文献
14.
Xuejun Zou Xinyong Li Zhenping Qu Qidong Zhao Yong Shi Yongying Chen Moses Tade Shaomin Liu 《Materials Research Bulletin》2012,47(2):279-284
TiO2–SiO2 composite nanotubes were successfully synthesized by a facile sol–gel technique utilizing ZnO nanowires as template. The nanotubes were well characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption analysis and UV–vis diffuse reflectance spectroscopy. The nanotubular TiO2–SiO2 composite photocatalysts showed diameter of 300–325 nm, fine mesoporous structure and high specific surface area. The results indicated that the degradation efficiency of gaseous toluene could get 65% after 4 h reaction using the TiO2–SiO2 composite as the photocatalyst under UV light illumination, which was higher than that of P25. 相似文献
15.
《Materials Science and Engineering: B》2001,79(1):55-62
Linear (visible photoluminescence) and non-linear (third-order susceptibility) optical properties have been measured for laser-synthesized crystalline Si nanoparticles. The observed luminescence is compared to similar measurements on nanocomposite aerogels prepared integrating the Si-nanoparticles into a continuous silica phase by sol–gel processing. The results show that incorporation of the Si-nanoparticles into a silica matrix by sol–gel technology is not detrimental to the PL (photoluminescence) emission intensity. The effect on the nanocomposites of annealing in air (at temperatures in the range of 300–500°C) has been investigated by means of PL and Raman spectroscopy. The obtained results indicate that the oxidation treatment induces the bleaching of the smaller luminescent particles and is not effective in reducing the average size. Micro-Raman mapping and TEM analysis of the nanocomposites have shown the presence of agglomerated nanoparticles (in the sub-micrometer range), as confirmed by dynamic light scattering (DLS) measurements on colloidal suspensions of the as-synthesized powders. 相似文献
16.
《Materials science & engineering. C, Materials for biological applications》2004,24(6-8):833-836
The nanosized silver particles are used to dope into the sol–gel film to prepare a biosensor. The horseradish peroxidase (HRP), mediator methylene blue (MB), nanosized silver particles and sol–gel solution are mixed and coated on the surface of glass carbon (GC) electrode to get the biosensor. The silver nanoparticles in the sol–gel film can adsorb the enzyme molecules and improve the sol–gel film conductivity. The biosensor has a high sensitivity, quickly response to H2O2 and good stability. The biosensor responds to H2O2 in the linear range from 1 μM to 1 mM. The detection limit was down to 0.4 μM when the signal to noise ratio is 3. The apparent Michaelis-Menten constant of the biosensor to H2O2 was estimated to be 1.2 mM, showing a high affinity. 相似文献
17.
Continuous alumina gel fibres were prepared by sol–gel method. The spinning sol was prepared by mixing aluminum nitrate, lactic acid and polyvinylpyrrolidone with a mass ratio of 10:3:1· 5. Thermogravimetry–differential scanning calorimetry (TG–DSC), Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibres. The Al2O3 fibres with a uniform diameter can be obtained by sintering gel fibres at 1200 °C. 相似文献
18.
Fabrication and characterization of bioactive composite coatings on Mg–Zn–Ca alloy by MAO/sol–gel 总被引:1,自引:0,他引:1
Gao JH Shi XY Yang B Hou SS Meng EC Guan FX Guan SK 《Journal of materials science. Materials in medicine》2011,22(7):1681-1687
High corrosion rate and accumulation of hydrogen gas upon degradation impede magnesium alloys’ clinical application as implants.
In this work, micro-arc oxidation (MAO) was used to fabricate a porous coating on magnesium alloys as an intermediate layer
to enhance the bonding strength of propolis layer. Then the composite coatings were fabricated using sol–gel method by dipping
sample into the solution containing propolis and polylactic acid at 40°C. The corrosion resistance of the samples was determined
based on potentiodynamic polarization experiments and immersion tests. Biocompatibility was designed by observing the attachment
and growth of wharton’s jelly-derived mesenchymal stem cells (WJCs) on substrates with MAO coating and substrates with composite
coatings. The results showed that, compared with that of Mg–Zn–Ca alloy, the corrosion current density of the samples with
composite coatings decreased from 5.37 × 10−5 to 1.10 × 10−6 A/cm2 and the corrosion potential increased by 240 mV. Composite coatings exhibit homogeneous corrosion behavior and can promote
WJCs cell adhesion and proliferation. In the meantime, pH value was relatively stable during the immersion tests, which may
be significant for cellular survival. In conclusion, our results indicate that composite coatings on Mg–Zn–Ca alloy fabricated
by MAO/sol–gel method provide a new type bioactive material. 相似文献
19.
A. W. Wren A. Coughlan F. R. Laffir M. R. Towler 《Journal of materials science. Materials in medicine》2013,24(2):271-280
Glass polyalkenoate cements (GPCs) have previously been considered for orthopedic applications. A Zn–GPC (BT 101) was compared to commercial GPCs (Fuji IX and Ketac Molar) which have a setting chemistry analogous to BT 101. Handling properties (working, T w and setting, T s times) for BT 101 were shorter than the commercial GPCs. BT 101 also had a higher setting exotherm (S x —34 °C) than the commercial GPCs (29 °C). The maximum strengths for BT 101, Fuji IX, and Ketac Molar were 75, 238, and 216 MPa (compressive, σ c), and 34, 54, and 62 MPa (biaxial flexural strengths, σ f), respectively. The strengths of BT 101 are more suitable for spinal applications than commercial GPCs. 相似文献
20.
A. W. Wren T. Keenan A. Coughlan F. R. Laffir D. Boyd M. R. Towler M. M. Hall 《Journal of Materials Science》2013,48(11):3999-4007
The structural role of Gallium (Ga) is investigated when substituted for Zinc (Zn) in a 0.42SiO2–0.40–xZnO–0.10Na2O–0.08CaO glass series, (where x = 0.08). Each starting material was amorphous, and the network connectivity (NC) was calculated assuming Ga acts as both a network modifier (1.23), and also as a network former. Assuming a network forming role for Ga the NC increased with increasing Ga concentration throughout the glass series (Control 1.23, TGa-1 2.32 and TGa-2 3.00). X-ray photoelectron spectroscopy confirmed both composition and correlated NC predictions. Raman spectroscopy was employed to investigate Q-structure and found that a shift in wavenumbers occurred as the Ga concentration increased through the glass series, from 933, 951 to 960 cm?1. Magic angle spinning nuclear magnetic resonance determined a chemical shift from ?73, ?75 to ?77 ppm as the Ga concentration increased, supporting Raman data. These results suggest that Ga acts predominantly as a network former in this particular Zn-silicate system. 相似文献