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1.
为进一步改善超细CaCO3的表面活性,利用γ-氨基丙基三乙氧基硅烷偶联剂(KH-550)对超细CaCO3进行表面改性,采用密炼工艺制备了超细CaCO3/热塑性丁苯橡胶(SBS)复合材料.通过红外光谱(FT-IR)、热重分析(TGA)、接触角测定仪(CAMI)和粒径分析等研究了改性前后超细CaCO3的结构变化,采用橡胶加工分析仪(RPA)和扫描电子显微镜(SEM)等对改性前后超细CaCO3的复合材料的力学性能和微观形貌进行了测试分析.结果表明:硅烷偶联剂KH-550与超细CaCO3粉体间能形成化学结合,修饰后的超细Ca-CO3能有效阻止颗粒间团聚,并均匀分散在橡胶胶体中,与胶体间形成物理和化学交联结构;改性后超细Ca-CO3在SBS体系中能形成网状结构,材料力学性能明显提高;当活化超细CaCO3的质量分数为20%时,能获得性能优异的复合材料. 相似文献
2.
Han Chen Yifeng ChenWenqiang Gong Kaixiong XiangBin Sun Jianhua Liu 《Materials Letters》2011,65(3):559-561
LiFePO4/C composite with network connections of nano-carbon wires was successfully prepared by using polyvinyl alcohol as carbon source. The composite was characterized by X-ray diffraction and transmission electron microscopic, and its electrochemical performance was investigated by galvanostatic charge and discharge tests. The experimental results show that LiFePO4 grains are tightly connected by the network of nano-carbon wires. Moreover LiFePO4/C composite exhibits high capacity of 168 mAh g−1 applied 15 mA g−1 current density (C/10), excellent cyclic ability and rate capability. When 1500 mA g−1 current density (10C) was applied, the high discharge capacity of 129 mAh g−1 has been obtained at room temperature. 相似文献
3.
Spinel Fe2VO4 was synthesized by solid state method and its properties were characterized using XRD, SEM, TG-DSC and specific surface area measurements. The average size of the particles was 500 nm. TG-DSC test demonstrated that the Fe2VO4 was thermally stable in nitrogen atmosphere within 300 °C. Lithium insertion into the sample at room temperature and 55 °C has been investigated and the highest discharge capacity approached 250 mAh/g at an average voltage of 0.6 V vs Li+/Li. Capacity retention was unexpectedly good at 1C discharge rate at room temperature and 55 °C. At 5C discharge rate, the specific capacity was still 136 mAh/g. The results show that the Fe2VO4 is a promising anode material due to its high specific capacity, thermal stability and rate performances. 相似文献
4.
A novel soft magnetic nanocomposite with FeCo particles encapsulated by amorphous SiO2 was synthesized using a co-precipitation combined H2 reduction method. The saturation magnetization of the (Fe70Co30)90/(SiO2)10 nanocomposite is as high as 200 emu/g, which is 4-5 times larger than that of traditional spinel ferrites. The frequency dependence of the complex initial permeability is intensely dependent upon the content of SiO2 insulating phase. With increasing the content of SiO2 to 10 wt.%, the cut-off frequency is drastically increased to over 1 GHz. The results show that a new high-frequency soft magnetic material with high saturation magnetization (Ms) can be achieved by introducing FeCo/SiO2 nanocomposite. 相似文献
5.
A novel approach, combining in-situ composite method with electrospinning, was used to prepare high magnetic Fe3O4/poly(vinyl alcohol) (PVA) composite nanofibers. Fe3O4 magnetic fluids were synthesized by chemical co-precipitation method in the presence of 6 wt.% PVA aqueous solution. PVA was used as stabilizer and polymeric matrix. The resulting Fe3O4/PVA composite nanofibers were characterized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffractometer (XRD), respectively. These composite fibers showed a uniform and continuous morphology, with the Fe3O4 nanoparticles embedded in the fibers. Magnetization test confirmed that the composite fiber showed a high saturated magnetization (Ms = 2.42 emµ·g-1) although only 4 wt.% content. 相似文献
6.
Co3O4-RuO2 composite nanofibers (NFs) were synthesized by an electrospinning method and were calcinated at 400°C for 1 hr in air. Scanning electron microscopy and high-resolution transmission electron microscopy (HRTEM) examinations show that all the synthesized NFs have uniform surface morphology and their diameters are in the range of ~ 30-~70 nm. X-ray diffraction (XRD) results show that crystalline Co3O4 phase and RuO2 phase coexist in the composite NF matrix which is confirmed by X-ray photoemission spectroscopy. In addition, the HRTEM energy-dispersive X-ray spectroscopy mapping results show that the Co3O4 and RuO2 phases are uniformly distributed across the NF matrix. 相似文献
7.
Preparation and characterization of magnetic nanofibrous composite membranes with catalytic activity
Xiang-Yu Ye 《Materials Letters》2009,63(21):1810-1813
Magnetic nanofibrous composite membranes were electrospun from the mixtures of poly(acrylonitrile-co-acrylic acid) (PANCAA) and Fe3O4 nanoparticles. Field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were used to characterize the composite membranes. TGA results indicate that the addition of Fe3O4 nanoparticles catalyzes the carbonization of PANCAA as well as dramatically increases the carbonization temperature. The intrinsic peroxidase-like activity of Fe3O4 nanoparticles was measured by the color reaction of phenol/4-amino antipyrine in the presence of H2O2. Under optimal conditions, the electrospun composite membranes show high peroxidase-like catalytic activity and reusability. Taking into account of the potentiality for separation, these as-prepared magnetic nanofibrous composite membranes will be applied in phenolic wastewater treatment. 相似文献
8.
DNA-like dye-sensitized solar cells based on TiO2 nanowire-covered nanotube bilayer film electrodes 总被引:1,自引:0,他引:1
This paper reports a two-step formation of a TiO2 nanowire-covered nanotube bilayer film technique and its application in DNA-like dye-sensitized solar cells. The bilayer film was prepared by the electrochemical anodization first and then the hydrothermal method. From the reflectivity spectrum and scanning electron microscopy it is observed that the nanowire layer on the top cannot only decrease the reflectivity of the film, but also play a role to modify the film cracks. Compared with the dye-sensitized solar cells based on a single layer electrode, the cell with the bilayer film showed higher photovoltaic parameters and a lower dark current, which is due to its higher light harvesting efficiency and lower charge recombination between the electrolyte and the substrates. 相似文献
9.
A Ni/TiO2 nanocomposite was successfully prepared by a pulse electrodeposition (PED) technique. Highly-ordered TiO2 nanotube arrays fabricated by anodization were employed as a substrate and loaded with Ni nanoparticles by PED. The influence of pulse electrodeposition parameters was investigated on the morphology of nickel electrodeposits. The nanocomposite was characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results indicated that Ni nanoparticles with average size ranging from 19 to 84 nm were obtained by changing electrodeposition parameters. At constant current off-time (toff) and pulse time of both negative and positive currents, the particle size decreased asymptotically with increasing amplitude of both negative and positive current. A progressive decrease of the particle size was observed with increasing current off-time at constant amplitude and pulse time of both negative and positive current. Increase in the deposition time at constant current off-time, amplitude and pulse time of both negative and positive current resulted in particle growth. 相似文献
10.
Improvement of magnetic characteristics and electrical properties of FeCoHfO/AlOx multilayered films
High permeability magnetic films can enhance the inductance of thin-film inductors in DC-DC converters. In order to obtain high permeability, effective uniaxial anisotropic field should be as low as possible. A multilayered technique (laminating the magnetic layers with oxide spacers) was exploited to improve the magnetic properties of thick films. The FeCoHfO/AlOx multilayered films were fabricated by dc reactive magnetron sputtering. Inserting an insulator (AlOx) layer can decrease the magneto-elastic anisotropy by reducing the residual stress of the FeCoHfO magnetic films. The anisotropic field and resistivity of the FeCoHfO/AlOx multilayered films were evidently improved by multilayered coating. With this optimum configuration of 9 layers structure [FeCoHfO (133 nm)/AlOx (10 nm)]9, low anisotropic field (HK = 65 Oe) and high resistivity (ρ ∼ 1350) μΩ cm were achieved. 相似文献
11.
The BaTiO3-CoFe2O4 (BTO-CFO) composite films were grown on SrTiO3 (STO) (100) substrates at 750 °C under various working pressures by pulsed laser deposition. The composite film grew into a supersaturated single phase at the working pressure of 10 mTorr, BTO and CFO (00 l) oriented hetero-epitaxial films on STO (100) at 100 mTorr, and a polycrystalline composite film at 500 mTorr. The slow growth rate at high working pressure led to the phase separation in the composite film. The CFO was compressively strained along out-of-plane due to the lattice mismatch with the BTO matrix phase. The BTO-CFO composite film grown at 100 mTorr showed reversible switching of ferroelectric polarization and magnetic hysteresis with strong magnetic anisotropy. 相似文献
12.
Mustafa Aghazadeh Ahmad Nozad Golikand Mehdi GhaemiTaher Yousefi 《Materials Letters》2011,65(10):1466-1468
A novel and interesting nanostructure of La(OH)3 was prepared by electrochemical method under mild conditions without any hard templates and surfactants. In this method, La(OH)3 was galvanostatically deposited from low-temperature nitrate bath on the steel substrate by electrogeneration of base. X-ray results showed that the obtained deposit has single crystalline hexagonal phase of La(OH)3. Morphological characterization revealed that the product has compact morphology with capsule-like structures having approximately an average diameter of 15 nm and the length of up to 50 nm. The results showed that low-temperature cathodic electrodeposition can be recognized as an easy and facile method for the synthesis of La(OH)3 nanocapsules. 相似文献
13.
Yanbao Fu 《Materials Letters》2009,63(22):1946-1948
SnO2/multi-walled carbon nanotube (MWCNT) composite was prepared via a diffusion method. Firstly the MWCNT was sonicated in a filtrate which was derived from a tin dichloride solution mixed with AgNO3 solution. Then the SnO2/MWCNT composite was prepared whereby, after calcination in N2 atmosphere, the salts inside the MWCNT decomposed to SnO2. The resulting composite was characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which indicated that SnO2 had infiltrated into the MWCNT and filled the interior. The subsequent evaluation of the electrochemical performance in lithium ion batteries showed that the SnO2/MWCNT composite had a reversible discharge capacity of 505.9 mAh?g− 1 after 40 cycles, as compared to 126.4 mAh?g− 1 for pure nano-SnO2. 相似文献
14.
An Au/Fe3O4 nanocomposite catalyst was fabricated through a simple deposition-precipitation method. The Au/Fe3O4 nanocomposite is a true nanocomposite that has single crystalline Au nanoparticles supported on single crystalline Fe3O4 nanoparticles. Lattice fringes from both Au and Fe3O4 single nanoparticles were simultaneously observed by transmission electron microscope (TEM). This nanocomposite catalyst showed much high activity in low temperature CO oxidation reaction. The Au/Fe3O4 nanocomposite catalyst reaches 100% CO conversion at 40 °C. In comparison, Au/commercial Fe3O4 catalyst needs 375 °C to convert CO. This Au/Fe3O4 nanocomposite is an ideal sample to study synergetic effect between the catalyst and the support at nanoscale. 相似文献
15.
Thermal stability of the TiAlN/Si3N4 nanoscale multilayered coating that was reported to show excellent hardness and toughness, has been investigated in terms of the nano-layered structure and hardness. TiAlN/Si3N4 nanoscale multilayered coatings with various thickness of Si3N4 layer were prepared by alternating deposition of TiAlN and Si3N4. In contrast to other nanoscale multilayered coating system such as AlN/CrN in which the intensity of the low angle XRD peaks decreases with increasing annealing temperature by interdiffusion between adjacent layers, the low angle XRD peak intensity of the nanoscale multilayered TiAlN/Si3N4 coatings increased after heat-treatment in an N2 atmosphere up to 800 °C. Such a thermal stability of the nano-layered structure is believed to be due to spinodal type phase separation of TiAlN and Si3N4, which increased the hardness value of the TiAlN/Si3N4 coating at high temperatures. 相似文献
16.
LiFePO4/C composite with carbon core structure was successfully prepared by using araldite as carbon source. The microstructure and morphology of LiFePO4/C composite were confirmed by X-ray diffraction and transmission electron microscopic observation. The experimental results show that this structure is entirely different from carbon coating. The LiFePO4/C composite forms a common core structure in which carbon is used as line core and carbon core is covered by nano-LiFePO4 grains. Moreover, the LiFePO4/C composite exhibits higher tap density of 1.66 g cm− 3, shows higher capacity about 162 mAhg− 1 applied 30 mAg− 1 current, excellent cyclic ability and rate capability about 139 mAhg− 1 applied 700 mAg− 1 current at room temperature. 相似文献
17.
为了提高石墨相氮化碳光催化性能,本文以尿素、硫脲、醋酸锌为前驱体,通过氧化热剥离与共混煅烧法分别制备g-C3N4纳米片和ZnO/g-C3N4异质结复合材料,并采用TEM、FTIR、XRD、UV-Vis DRS、BET等表征手段对制备的催化剂进行结构表征。以罗丹明、大肠杆菌为探针,考察了催化剂的光催化降解性能和抑菌活性。结果表明:以尿素和硫脲为前驱体,经过氧化热剥离处理后能得到的g-C3N4 2D纳米片,其比表面积更大、光催化性能更加优异,且其对罗丹明的降解率较未剥离的g-C3N4提高了21.2%。在40 min氙灯照射下,纯g-C3N4并未表现出良好的抑菌性能,而通过ZnO复合制备的ZnO/g-C3N4异质结复合材料,在光催化降解率和抑菌活性方面均有很大提高,其中复合20%ZnO制得的ZnO异质结复合材料表现出最佳的光催化性能... 相似文献
18.
Y.X.Chen ) L.H.He ) P.J.Shang ) Q.L.Tang ) Z.Q.Liu ) H.B.Liu ) L.P.Zhou ) ) College of Materials Science Engineering Hunan University Changsha China ) Shenyang National Laboratory for Materials Science 《材料科学技术学报》2011,27(1):41-45
Micro-sized(1030.3±178.4 nm) and nano-sized(50.4±8.0 nm) Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe2O3 particles synthesized by means of a hydrothermal process.The morphology and microstructure of the micro-sized and the nano-sized Fe3O4 particles were characterized by X-ray diffraction,field-emission gun scanning electron microscopy,transmission electron microscopy and highresolution electron microscopy.The micro-sized Fe3O4 particles exhibit porous structure,while the nano-sized Fe3O4 particles are solid structure.Their electrochemical performance was also evaluated.The nano-sized solid Fe3O4 particles exhibit gradual capacity fading with initial discharge capacity of 1083.1 mAhg-1 and reversible capacity retention of 32.6% over 50 cycles.Interestingly,the micro-sized porous Fe3O4 particles display very stable capacity-cycling behavior,with initial discharge capacity of 887.5 mAhg-1 and charge capacity of 684.4 mAhg-1 at the 50th cycle.Therefore,77.1% of the reversible capacity can be maintained over 50 cycles.The micro-sized porous Fe3O4 particles with facile synthesis,good cycling performance and high capacity retention are promising candidate as anode materials for high energy-density lithium-ion batteries. 相似文献
19.
AbstractAt the present time, color homogeneity and luminous flux are the two essentials utilized to appraise high-quality phosphor-converted LEDs (pcLEDs). In this paper, we present the search for the optimal selection among scattering enhancement particles (SEPs) to apply to improve these essentials for pcLEDs having correlated color temperature of 8500 K. The interested contenders include CaCO3, CaF2, SiO2, and TiO2. Each of them is added to yellow phosphor compounding (Y3Al5O12:Ce3+). Firstly, the LightTools program is employed to do the optical simulations. Secondly, the obtained results are verified and analyzed based on Mie scattering theory. The scattering computation of SEPs includes the scattering coefficients, the anisotropic scattering, the reduced scattering and the scattering amplitudes at 455 and 595 nm. It is observed that TiO2 particles provide the highest color homogeneity among the SEPs but the luminous flux reduces significantly as its concentration increases. By using CaCO3 particles, the highest luminous flux of 792 lm is obtained. CaCO3 particles can also reduce the deviation of color correlated temperature to 620 K at 30% concentration. Therefore, CaCO3 particles should be selected to enhance both color homogeneity and luminous flux. 相似文献
20.
Changyuan Hu Shuwang Duo Tingzhi Liu Wenkui Li Rongfa Zhang 《Materials Letters》2010,64(22):2472-2474
Anatase TiO2 coated multiwalled carbon nanotube (MWNT) nanocomposites were prepared by combining the sol-gel method with a self assembly technique at a low temperature. XRD, TEM, FTIR and XPS spectra were applied to characterize the crystal phase, microstructure, and other physicochemical properties of the sample. The results showed that MWNTs were covered with a 12-20 nm thickness layer of anatase TiO2 or surrounded by a 30 -290 nm thickness coating of anatase TiO2. The layer or coating is constructed of TiO2 nanoparticles about 5.8 nm. Furthermore, as-prepared composite was rich in surface hydroxyl groups. 相似文献