溶胶-凝胶法制备环氧树脂/纳米SiO_2复合材料中纳米粒子的分散性研究

用溶胶-凝胶法制备环氧树脂/纳米SiO2复合材料,研究了在脱除溶剂以及反应副产物过程中温度、表面改性剂对纳米SiO2粒子的分散性、固化后样品力学性能的影响。研究表明:纳米SiO2的引入对环氧树脂的力学性能有一定的提高;随着体系溶剂脱除温度的升高纳米粒子的团聚明显;加入表面改性剂能够阻止纳米粒子的团聚,硅烷偶联剂KH550比表面活性PEG剂能够更好地阻止纳米粒子的团聚;但是表面活性剂PEG的加入会使纳米复合材料的力学性能有一定程度的下降。

溶胶-凝胶法合成ZrO_2-8%Y_2O_3纳米粉体相转变及晶粒生长行为研究

以醋酸为水解催化剂和螯合剂,采用溶胶-凝胶法合成ZrO2-8%Y2O3(8YSZ)粉末,利用XRD、SEM方法研究纳米8YSZ粉末热处理后的相成分、晶粒尺寸和形貌的变化,并分析纳米8YSZ粉末中的晶粒生长行为。结果表明:溶剂中添加乙醇不利于纳米8YSZ粉末四方相(t)的稳定;在400～1200℃范围内,随着热处理温度的升高晶粒尺寸逐渐增大;然而纳米8YSZ粉末的晶粒生长活化能在低温区和高温区有所不同,热处理温度低于800℃时的晶粒生长活化能(9.71kJ/mol)明显小于热处理温度高于800℃时的晶粒生长活化能(43.06kJ/mol),这有利于t-8YSZ在低温下结晶,在高温下保持四方相的稳定性。

β-SiC纳米线增韧58S活性生物玻璃陶瓷的研究

目的:测定所制备58S生物医用玻璃陶瓷的机械性能和生物活性。方法:采用溶胶-凝胶法制备单相58S玻璃A组,以超长β-SiC纳米线为增韧体,根据所混合SiC纳米线的质量分数15%、25%、30%和40%制备复合生物玻璃陶瓷B、C、D、E组(每组5个试件),烧结后均加工成标准试件。测定三点弯曲强度及断裂韧性;扫描电子显微镜观察基体断口形貌。结果:随超长β-SiC纳米线质量分数的增加,58S生物玻璃陶瓷基体的抗弯强度先上升后下降,而断裂韧性随β-SiC纳米线质量分数的增多呈线性增加。统计分析结果表明,各组两两间三点弯曲强度和断裂韧性的差异均有统计学意义(P<0.05)。复合生物玻璃陶瓷在SBF中的XRD衍射结果表明仍有羟基磷灰石的成核和生长。结论:新方法合成的58S活性生物医用玻璃陶瓷可兼备优良的机械性能与生物活性。

Sol-gel synthesis and photoluminescence of LaPO_4:Eu^(3+) nanorods

Monoclinic LaPO4 nanostructures with uniform rod shape have been successfully synthesized by a simple sol-gel method.The procedure involves formation of homogeneous,transparent,metal-citrate-EDTA gel precursors,followed by calcination to promote thermal decomposition of the gel precursors to yield the LaPO4 nanoparticles.Their morphologies and structures were characterized by XRD,TEM,TG-DSC and HRTEM.The results indicate that single monoclinic phase LaPO4 nanorods are readily obtained at 800 ℃ within 3 h.Furthermore,photoluminescence(PL) characterization of the Eu3+-doped LaPO4 nanocrystals was carried out.The effects of calcination temperatures and Eu3+ doping content on the PL properties were elaborated in detail.Room-temperature photoluminescence(PL) characterization reveals that the optical brightness as well as the intensity ratio of 5D0-7F1 to 5D0-7F2 is highly dependent on the calcination temperature,and the Eu0.05La0.95PO4 nanophosphor shows the relatively promising PL performance with the most intense emission.

Structure,morphology and opto-magnetic properties of Bi_2MoO_6 nano-photocatalyst synthesized by sol-gel method

Bismuth molybdate （Bi2MoO6） nano-particles （NPs） were synthesized using bismuth nitrate, ammonium molybdate, citric acid and ethyl cellulose by a simple sol-gel method. The structure, morphology, opto-magnetic and photocatalytic properties of the obtained powder were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, high resolution scanning electron microscopy （HRSEM）, energy dispersive X-ray （EDX）, ultraviolet-visible diffuse reflectance spectra （DRS）, photoluminescence （PL） spectra and vibrating sample magnetometer （VSM） techniques. The XRD, FT-IR and EDX results indicate that the resultant powder is pure and single phase crystalline Bi2MoO6 with orthorhombic structure. The HRSEM image shows that the morphology of obtained powder consists with well defined nano-particles structure. The VSM results show superparamagnetic behavior of the obtained nano-particles. The photocatalytic activity of Bi2MoO6 nano-particles was performed. The addition of TiO2 catalyst enhances the photocatalytic activity of Bi2MoO6 nano-particles. The catalysts Bi2MoO6, TiO2 and mixed oxide catalyst Bi2MoO6-TiO2 nano-composites （NCs） were tested for the photocatalytic degradation （PCD） of 4-chlorophenol （4-CP）. It is found that the PCD efficiency of Bi2MoO6-TiO2 NCs is higher than that of pure Bi2MoO6 and TiO2 catalysts.

Performance of carbon-coated nano-ZnO prepared by carbonizing gel precursor as anodic material for secondary alkaline Zn batteries

Although carbon coating can improve the cycle life of anode for alkaline Zn batteries, the specific capacity reported is still lower compared with nanosized ZnO. Herein, carbon-coated nanosized ZnO(nano-ZnO@C) was synthesized by one-step heat treatment from a gel precursor in N2. Commercial ZnO and homemade ZnO prepared similarly in air atmosphere were studied for comparison. Structure analysis displayed that both nano-ZnO@C and homemade ZnO had a porous hierarchical agglomerated architecture produced from primary nanoparticles with a diameter of approximately 100 nm as building blocks. Electrochemical performance measurements showed that nano-ZnO@C displayed the highest electrochemical activity, the lowest electrode resistance, the highest discharge capacity(622 m A·h/g), and the best cyclic stability. These properties were due to the combination of nanosized ZnO and the physical capping of carbon, which maintained the high utilization efficiency of nano-ZnO, and simultaneously prevented dendrite growth and densification of the anode.

Synthesis of NiMoO_4 nanoparticles by sol-gel method and their structural,morphological,optical,magnetic and photocatlytic properties

Nickel molybdate(NiMoO4)nanoparticles(NPs)were synthesized by sol-gel method.Utilizing water as solvent providescrystalline nanostructures.These nanocrystals were structurally characterized by X-ray diffraction,energy dispersive X-ray analysis(EDX),and Fourier transform infrared spectra.Compositional stoichiometry was confirmed by EDX technique.The size and shapewere observed by scanning electron microscopy(SEM)and transmission electron microscope(TEM).It was found that the obtainedNPs were pure and single phase crystalline with monoclinic structure.The optical properties were studied by ultraviolet-visiblediffuse reflectance spectroscopy(UV-Vis-DRS)and photoluminescence(PL)measurements at room temperature.The magneticproperties were studied by vibrating sample magnetometer(VSM)and results showed superparamagnetic behavior of the obtainednanoparticles.Photocatalytic activity of NiMoO4was studied.The photocatalytic activity of NiMoO4was enhanced with the additionof TiO2.The catalysts NiMoO4,TiO2and NiMoO4-TiO2nanocomposites(NC)were tested for photocatalytic degradation(PCD)of4-chlorophenol(4-CP).It was found that PCD efficiency of NiMoO4-TiO2NC was higher than that of pure NiMoO4and TiO2.

PREPARATION OF POLYSULFONAMIDE/TiO_2 NANOCOMPOSITES BY SOL-GEL

Polysulfonamide(PSA)was synthesized at room temperature,the polymerization based on terephthaloyl chloride and 3,3’-diaminodiphenylsulfone in the common solvent N,N-Dimethyl-acetamide(DMAc).Polysulfonamide/titanium oxide nanocomposites were prepared by sol-gel method.Tetrabutyl titanate(TBT)was added into the polysulfonamide solution,at the same time,some water was mixed to make the TBT hydrolyze.In the process,hydrochloric acid was used to catalyze the reaction.The polysulfonamide chemistry structure was characterized by FT-IR spectrum.Atomic force microscopy(AFM)was employed to observe the microstructure of the composite film.The thermal property was investigated by TGA.The results show that we have succeeded to synthesize the polysulfonamide,TiO2 particles were well distributed in the composite film and average size was about 20 nm on average,the heat-resistance of nanocomposite was batter than the pure polysulfonamide.

Synthesis and Characterization of Sol-Gel Derived MgO/CNTs Nanocomposite

In this research, synthesis of magnesium oxide-multi walled carbon nanotube （MgO/MWCNTs） nanocomposite is reported using sol-gel method in which magnesium nitrate is added to aqueous solution. The structure of MWCNTs and MgO/MWCNTs composite has been characterized by analyzing the X-ray diffraction pattern （XRD）, Fourier Transform Infrared （FT-IR） spectra and Scanning Electron Microscopy （SEM） images. Experimental results indicate that the surface of purified MWCNTs sample is covered homogenously by a layered of MgO nanoparticles.

Structural and Magnetic Properties of Chemically Synthesized Pd-Modified NiFe2O4 Nanoparticles

Magnetic nanoparticles of NiFe2O4-Pd composites have been synthesized using a simple, low cost, sol-gel auto-combustion method. As-prepared samples were sintered at 800℃ for 6 h in order to develop the crystalline phase. X-ray diffraction confirmed the spinel structure of the ferrite samples. Structural morphology and size of the nanoparticles were evaluated using a field emission scanning electron microscope. Magnetic hysteresis loops were obtained at 300 and 100 K using a physical properties measurement system. The value of saturation magnetization was observed to decrease at the temperatures with the increase of Pd contents up to 5% but then a sudden rise in saturation magnetization was observed for the addition of 10% Pd in NiFe2O4.

Preparation, Properties and Application of Polymeric Organic-Inorganic Nanocomposites

Six preparation methods for polymeric organic-inorganic nanocomposites and their respective mechanisms and features are reviewed. The extraordinary properties of polymeric organic-inorganic nanocomposites are discussed,and their potential applications are evaluated.

Optimization of the preparation process of nano TiO2 with sol-gel method at low temperature

In this paper, preparation process of nano TiO2 with sol-gel method at low temperature was optimized by response surface method. The nano TiO2 was analysised by DRS and XRD. Result show that： 20mL tetrabutyl titanate, 10mL acetic acid, 6mL ethanol dosage, aging time was 29h, aging temperature was 36℃, Nano TiO2 was prepared under the condition. Particle size of nano particles was 37.3nm, Photodegradation rate was 90.2%. It had good photocatalytic ability.

The Physical Properties and Photocatalytic Activity of CulTEA Doped TiO2-Nanoparticles Prepared by the Sol-Gel Process

Cu/TEA-doped TiO2 nanoparticles were prepared by the sol-gel process. Titanium （IV） isoproxide, copper （II） nitrate trihydrate and triethanolamine were used as precursors and calcined at a temperature of 400℃ for 2 h with a heating rate of 10℃/min to produce powders. Different interstitial amounts of TEA were added in the range of 0 mol% to 15 mol% of TiO2. The X-ray diffractrometer patterns show the TiO2 nanocomposites have a high anatase phase. It was also apparent that doped TEA has an effect on the crystallite size of TiO2 composite nanoparticles. The morphology of the composite powders was characterized by scanning electron microscope. The photocatalytic activity of Cu/TEA-doped TiO2 nanoparticles was evaluated through the degradation of methylene blue under UV irradiation. The results showed that 1 mol% TEA of TiO2 nanocomposites exhibited high photocatalytic activity and a small crystallite size.

Sol-Gel Synthesis and Structure-Property Relations in Silver Nanoparticles-Dispersed in GeO2 Matrix

Synthesis of Ag nanoparticles dispersed in germanium dioxide （GeO2） matrix was performed via sol-gel route. Analysis of the powder X-ray diffraction （XRD） pattern shows fcc cubic unit cell of Ag with lattice parameters： a = 4.0884 A, space group Fm-3m. Energy dispersive analysis of X-rays （EDAX） results show the presence of only GeO2 and Ag in the sample. The average crystallite sizes of Ag particles determined by Scherrer＇s relation are found to be i 8-47 nm. Observed sharp electron paramagnetic resonance （EPR） lineshapes at 8, 70 and 300 K with g-values of 2.004, 2.004, and 2.004, respectively, show that the Ag （5s~） electrons are localized in the Ag nanoparticles. The calculated value of the magnetic susceptibility is 1.014~ 10-5 emu/gG from the observed magnetic moments data at 300 K, which shows fairly strong paramagnetic nature of the material. Refinement of Ag crystal structure in space group Fm-3m with Ag atoms in 4（a） position shows the agreement bond length as 2.8909 ,＆. Calculated density of states below Fermi factors Rp= 67.22%, Rwp= 75.7%, Rexp= 0.06%, Z = 4 and Ag-Ag energy, EF, from -2 to -8 eV are due to valence d orbitals of Ag.

Nanodiamond incorporated sol−gel coating for corrosion protection of magnesium alloy

Sol-gel coatings containing various amounts of hydroxylated nanodiamond(HND)particles were applied on the magnesium alloy for corrosion protection.The micrometric defects in the sol-gel coating completely disappeared after adding 0.01,0.02 and 0.05 wt.%of the HND nanoparticles.The AFM analyses showed that average roughness of the sol-gel film is about 6.7 nm which increases to 16.1 and 20.2 nm after incorporating 0.005 and 0.02 wt.%of the HNDs,respectively.The corrosion resistance of the coatings was tested in Harrison’s solution by means of EIS technique after 15,30,60 and 120 min immersion.The corrosion resistance of the sol-gel coating was remarkably enhanced by incorporating different contents of the HNDs and the best result was obtained for 0.01 wt.%.The results of the EIS experiments were confirmed by the potentiodynamic polarization tests.The corrosion resistance enhancement was attributed to the film compactness(due to the chemical interaction with the HNDs),formation of tortuous pathways for diffusion of the corrosive solution,and filling of the defects by the nanoparticles.However,the beneficial effect of the HNDs on the corrosion resistance gradually diminished as the content of nanoparticle was increased.Finally,the micromorphology of the sol-gel nanocomposites was studied after the corrosion tests.

Grain Growth Kinetics of BaTiO3 Nanocrystals During Calcining Process

BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate （Ba（CH3COO2） and tetrabutyl titanate （Ti（OC4H9）4） as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry （TG/DSC）, X-ray diffraction （XRD） and transmission electron microscope （TEM）. The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

Oxidative Coupling of Methane over Li/MgO： Catalyst and Nanocatalyst Performance

The Li/MgO catalyst and nanocatalyst were prepared by the incipient wetness impregnation and sol-gel method, respectively. The catalytic performance of the Li/MgO catalyst and nanocatalyst on oxidative coupling of methane was compared. The catalysts prepared in two ways were characterized by X-ray powder diffraction, Brunauer-Emmett-Teller surface and transmission electron microscope. The catalyst was tested at temperature of 973-1073 K with constant total pressure of 101 kPa. Experimental results showed that Li/MgO nanocatalyst in the oxidative coupling of methane would result in higher conversion of methane, higher selectivity, and higher yield of main products （ethane and ethylene） compared to ordinary catalyst. The results show the improved influence of nanoscale Li/MgO catalyst performance on oxidative coupling of methane.

织物抗起毛起球新技术现状分析

介绍了目前一些纺织品的起毛起球成因,分析了纤维、纱线、织物、加工及服用等因素对起毛起球的影响。根据不同种类的纤维和织物(棉麻、涤纶、腈纶、毛),提出了相关的抗起毛起球新工艺。

Magnetic and microwave absorption properties of Ni_(1-x)Zn_xFe_2O_4 nanocrystalline synthesized by sol-gel method

Ni1-xZnxFe2O4(0≤x≤1,in steps of 0.1) nanocrystallines were synthesized by sol-gel route.The doping effects of zinc on structural,magnetic and microwave absorption properties were investigated in detail.X-ray diffraction(XRD) results show that all the samples are single-phase spinel structure.The magnetic and microwave absorption properties are strongly dependent on the zinc content,which can be understood in terms of the cations redistribution in spinel tetrahedral and octahedral sites with the increase of zinc content.The magnetic measurement shows the antiferromagnetic nature of the samples for x=0.9 and x=1.0.The saturation magnetization reaches the maximum of 3.35μB/f.u.at x=0.5.The optimal reflection loss(RL) of-29.6 dB is found at 6.5 GHz for an absorber thickness of 5 mm.The RL values exceeding 10 dB are obtained for the absorber in the range of 3.9-8.9 GHz.These Ni1-xZnxFe2O4 nanocrystallines may be attractive candidates for electromagnetic wave absorption materials.

Nanocomposite LiFePO_4·Li_3V_2(PO_4)_3/C synthesized by freeze-drying assisted sol-gel method and its magnetic and electrochemical properties

Nano-sized LiFePO_4·Li_3V_2（PO_4）_3/C was synthesized via a sol-gel route combining with freeze-drying. X-ray diffraction results show that this composite mainly consists of olivine Li Fe PO4 and monoclinic Li3 V2（PO4）3 phases with small amounts of V-doped LiFePO_4 and Fe-doped Li_3V_2（PO_4）_3. The magnetic properties of LiFePO_4·Li_3V_2（PO_4）_3/C are significantly different from LiFePO_4/C. Trace quantities of ferromagnetic impurities and Fe_2P are verified in LiFePO_4/C and LiFePO_4·Li_3V_2（PO_4）_3/C by magnetic tests, respectively. LiFePO_4·Li_3 V_2（PO_4）_3/C possesses relatively better rate capacities and cyclic stabilities, especially at high charge-discharge rates.The initial discharge capacities are 136.4 and 130.0 mA h g^（-1）,and the capacity retentions are more than 98% after 100 cycles at 2C and 5C, respectively, remarkably better than those of LiFePO_4/C. The excellent electrochemical performances are ascribed to the mutual doping of V^（3＋）and Fe^（2＋）, complementary advantages of LiFePO_4 and Li_3V_2（PO_4）_3 phases, the residual high-ordered carbon and Fe_2P with outstanding electric conductivity in the nanocomposite.