首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
《Ceramics International》2016,42(11):12860-12867
In this work, X-ray diffraction analysis and optical properties of pure and Ba-doped ZnO nanoparticles prepared by the precipitation method were investigated. X-ray analysis was employed to evaluate the micro structural parameters of ZnO nanoparticles in terms of crystallite sizes and lattice strain by the Williamson–Hall method. The average crystallite size of Ba-doped ZnO nanoparticles estimated by the Williamson–Hall method varied as the doping concentration increased. The effect of Ba doping on the photoluminescence (PL) emission spectrum of ZnO was also investigated. The temperature dependence of the PL emissions was also studied, and it was found that at low temperature, the samples show stronger emissions than those at room temperature in both UV and visible regions. As a final point, the FT–IR reflection spectrum along with Kramers–Kronig (K–K) method and classical dispersion theory was applied to obtain optical properties of the samples at low frequency infrared regime.  相似文献   

2.
The nanocomposites were manufactured by the incorporation of modified ZnO into the poly(vinyl chloride). ZnO nanoparticles were modified with diacid containing alanine amino acid. Ultrasonic irradiation was used for all process. The PVC/ZnO@DA nanocomposites were investigated by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, thermogravimetric, and mechanical analysis. Results showed the uniform dispersion of particles in the polymer matrix and ZnO@DA nanoparticles in quantum dot size. The optical properties of PVC were affected by the incorporation of modified quantum dot ZnO; also mechanical properties of PVC/ZnO@DA nanocomposites were improved.  相似文献   

3.
Transparent ZnO/epoxy nanocomposites with high-UV shielding efficiency were reported in this paper. First, zinc oxide (ZnO) precursor was synthesized via the homogeneous precipitation method and ZnO nanoparticles were then made by calcination of the precursor at different temperature. The structural properties of the as-prepared ZnO nanoparticles were studied in detail using thermogravimetry (TGA), differential thermal analysis (DTA), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR) and transmission electron microscopy (TEM), respectively. Transparent ZnO/epoxy nanocomposites were subsequently prepared from transparent epoxy (EP-400) and as-prepared ZnO nanoparticles via in situ polymerization. Optical properties of ZnO/epoxy nanocomposites, namely visible light transparency and UV light shielding efficiency, were studied using an ultraviolet-visible (UV-vis) spectrophotometer. The optical properties of the as-obtained nanocomposites were shown to depend on ZnO particle size and content. The nanocomposite containing a very low content (0.07% in weight) of ZnO nanoparticles with an average particle size of 26.7 nm after calcination at 350 °C possessed the most optimal optical properties, namely high-visible light transparency and high-UV light shielding efficiency, that are desirable for many important applications.  相似文献   

4.
《Ceramics International》2017,43(11):8488-8496
In this paper, the structural, optical and magnetic properties of pure ZnO and Fe/Co co-doped ZnO nanoparticles are presented. Rietveld refinement of XRD pattern revealed the single phase wurtzite structure for prepared samples. FTIR study confirmed the formation of tetrahedral coordination between zinc and oxygen ions. SEM and TEM techniques were used to examine the morphology of samples. The absorption spectra showed the decrease in optical energy band gap with Fe/Co co-doping in ZnO. PL spectra demonstrated five peaks correspond to the ultraviolet region, violet, violet-blue, blue-green and green in the visible region. Emission peak in the UV region is attributed to near band-edge excitonic emission. Other four emission peaks in PL spectra are related to different defect states. M-H curve showed room temperature ferromagnetic (RTFM) behaviour of doped ZnO sample. This paper enhances the understanding of structural, optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals for application in spintronics, solar cells, and ceramics.  相似文献   

5.
The polymeric blend was fabricated with crystalline poly(vinylidene fluoride) (PVDF)/amorphous functionalized-poly(methyl methacrylate) (PMMA) in 70/30 w/w ratio by chemical mixing method. Functionalization of PMMA was achieved with 2-amino-5-nitrobenzoic acid. The prepared polymer blend was used as a matrix to synthesize nanocomposites with undoped/doped zinc oxide (ZnO) nanoparticles. Doping in ZnO was achieved with vanadium, sulfur, and dysprosium elements as a dopant. The structural, optical, electronic, and morphological properties of undoped/doped nanosized ZnO and blended nanocomposites were accessed through sophisticated analytical techniques, that is, Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis), UV–vis–diffuse reflectance spectra, nuclear magnetic resonance, fluorescence spectroscopy, X-ray diffraction (XRD), transmission electron microscopy, and scanning electron microscopy. The FTIR band at 1165–1176 cm−1 in functionalized-PMMA indicate the formation of aliphatic C-N bond along with aromatic 1H chemical shift (δ) at 7.134, 7.829 and 8.210 ppm confirm the successfully functionalization of PMMA. The prominent XRD peak at 2θ = 20.8° in nanocomposites shown improvement in β-phase of PVDF. The results show that Dy doped ZnO nanoparticles create remarkable effect on various properties of nanocomposites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47116.  相似文献   

6.
In this work, polymer nanocomposites consisting of a poly(vinyl chloride) (PVC) and polyvinylidene fluoride (PVDF) polymer network with ZnO nanoparticles as a dopant were prepared by solution casting. An XRD study of the PVC/PVDF/ZnO polymer nanocomposites shows predominantly sharp and high intensity peaks. However, the intensity and sharpness of the XRD peaks decreases with further increment in loading of ZnO (wt%), which reveals a proper intercalation of ZnO nanoparticles within the PVC/PVDF polymer system. Fourier transform infrared spectroscopy has been used to verify the chemical compositional change as a function of ZnO nanoparticle loading. TGA analysis clearly describes the thermal degradation of the pure polymer and polymer nanocomposites. The complex dielectric function, AC electrical conductivity and impedance spectra of these nanocomposites were investigated over the frequency range from 10 Hz to 35 MHz. These spectra were studied with respect to the Wagner ? Maxwell ? Sillars phenomenon in the low frequency region. Nyquist plots of the PVC/PVDF/ZnO nanocomposites were established from impedance measurements. The temperature‐dependent DC ionic conductivity obtained from the Nyquist plots follows Arrhenius behaviour. © 2016 Society of Chemical Industry  相似文献   

7.
Ag-doped ZnO nanoparticles with high and stable photocatalytic activity were prepared by polymer-assisted freeze-drying method with simple process and without organic solvents used. The structural morphology and optical properties of Ag-doped ZnO nanoparticles were characterized by X-ray Diffraction (XRD), Inductive Coupled Plasma Optical Emission Spectrometry (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM) and high resolution TEM (HRTEM) with energy dispersive X-ray spectroscopy, Ultraviolet-visible Diffuse Reflectance Spectroscopy (UV–vis DRS), X-ray Photoelectron Spectroscopy (XPS) and Fourier Transmission Infrared Spectroscopy (FTIR). Moreover, the thermoanalytical measurements (TGA–DTG) analysis is carried out for proper calcination temperature. XRD results show that Ag nanoparticles were successfully doped into ZnO lattice, and UV–vis DRS results indicate that the doped Ag nanoparticles result in ZnO exhibiting enhanced light trapping capability in the 400?nm and 600?nm range. The photocatalytic activity of Ag-doped ZnO was examined by analyzing the degradation of methyl orange (MO) and methylene blue (MB) dyes under UV light and solar light irradiation, and the results show that all Ag-doped ZnO nanoparticles exhibit better photocatalytic activity than those of pure ZnO nanoparticles at the same degradation conditions; especially the synthesized Ag-ZnO nanoparticles are easy to be recycled and have high photocatalytic stability. Based on the experimental results, the photocatalytic electron transfer path and the photocatalytic mechanism of Ag-ZnO nanoparticles under UV and solar irradiation conditions are explained and clarified.  相似文献   

8.
PVC/PVDF/CPE共混体系研究   总被引:6,自引:0,他引:6  
以CPE作为PVC/PVDF的增容剂,研究了PVC/PVDF/CPE三元共混新体系。对不同组成的共混物的物理机械性能进行测试,分析了讨论了PVDF/CPE的增韧效果和机理。结果表明:CPE对PVC/PVDF共混体系有明显的增容作用,PVDF/CPE并用对增韧PVC有显著的协同效应。  相似文献   

9.
Zinc oxide nanoparticles were prepared by uniform precipitation using urea hydrolysis. The ZnO precursor was slowly deposited from aqueous solution. Anionic surfactant was added into solution to block ZnO crystal growth and its agglomeration. Then ZnO nanoparticles were synthesized by the calcination of the precursor at high temperature. Transmission electron microscope (TEM) observation and particle size analyzer demonstrated that the ZnO nanoparticle exhibited nearly spheric shape with 10-40 nm particle size. The surface of the ZnO nanoparticle was modified by methacryloxypropyltrimethoxysilane (MPS). FT-IR (Fourier transform-infrared spectrophotometry) and XPS (X-ray photoelectron spectrophotometry) revealed that MPS was grafted onto the zinc oxide nanoparticle. XRD (X-ray diffraction) showed that the ZnO nanoparticle was a hexagonal crystal with a perfect crystalline structure, and its crystalline morphology was not altered through surface modification. The activation index (AI) of the modified ZnO nanoparticle was measured. It was found that the surface of the ZnO nanoparticle was changed from hydrophilicity into hydrophobicity via surface modification, implying the enhancement of its compatibility with organic polymers. FE-SEM (field scanning electron microscopy) showed that the modified ZnO nanoparticles were homogeneously dispersed in PVC matrices. Consequently, ZnO nanoparticles were integrated with PVC matrices by the grafting organic molecule.  相似文献   

10.
The main aim of this study is to investigate the effect of silver‐doped zinc oxide (Ag‐ZnO) loading on the structural, morphological, thermal and electrical properties, and gas sensing behavior of polypyrrole (PPy)/phenothiazine (PTZ)‐blend nanocomposites. The composites are characterized by FTIR, XRD, SEM, TEM, DSC, TGA, and impedance studies. FTIR spectra exhibit the presence of Ag‐ZnO in the PPy/PTZ blend. XRD analysis shows that the semicrystalline behavior of the polymer blend is greatly enhanced by the addition of Ag‐doped ZnO particles. Uniform dispersion of nanoparticles in the polymer is obtained from SEM analysis. The TEM images confirm the presence of spherically shaped nanoparticles in PPy/PTZ blend with a size of 10–25 nm. The DSC measurement indicates that the glass transition temperature of PPy/PTZ blend was significantly improved in the presence of Ag‐doped ZnO nanoparticles. The thermal decomposition temperature of nanocomposite obtained from TGA shows an increase with increase in the content of Ag‐ZnO particles. The incorporation of Ag‐doped ZnO nanoparticles to PPy/PTZ blend exhibit increase in the AC conductivity and dielectric properties of the nanocomposite, due to the pilling of charges at the extended interface of the composite system. The DC conductivity of the nanocomposite increases with the loading of nanoparticles. The ammonia gas sensing performance of PPy/PTZ/Ag‐ZnO nanocomposite is analyzed, and the result shows that the fabricated blend composite can be used as a promising candidate for the easy access of gas molecules. J. VINYL ADDIT. TECHNOL., 26:187–195, 2020. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.  相似文献   

11.
Zinc oxide nanoparticles were prepared by uniform precipitation using urea hydrolysis. The ZnO precursor was slowly deposited from aqueous solution. Anionic surfactant was added into solution to block ZnO crystal growth and its agglomeration. Then ZnO nanoparticles were synthesized by the calcination of the precursor at high temperature. Transmission electron microscope (TEM) observation and particle size analyzer demonstrated that the ZnO nanoparticle exhibited nearly spheric shape with 10–40 nm particle size. The surface of the ZnO nanoparticle was modified by methacryloxypropyltrimethoxysilane (MPS). FT-IR (Fourier transform-infrared spectrophotometry) and XPS (X-ray photoelectron spectrophotometry) revealed that MPS was grafted onto the zinc oxide nanoparticle. XRD (X-ray diffraction) showed that the ZnO nanoparticle was a hexagonal crystal with a perfect crystalline structure, and its crystalline morphology was not altered through surface modification. The activation index (AI) of the modified ZnO nanoparticle was measured. It was found that the surface of the ZnO nanoparticle was changed from hydrophilicity into hydrophobicity via surface modification, implying the enhancement of its compatibility with organic polymers. FE-SEM (field scanning electron microscopy) showed that the modified ZnO nanoparticles were homogeneously dispersed in PVC matrices. Consequently, ZnO nanoparticles were integrated with PVC matrices by the grafting organic molecule.  相似文献   

12.
SiO2 nanowires, made from natural chrysotile, were used to synthesize zinc oxide (ZnO)/SiO2 composites by chemical precipitation. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, and Fourier transform infrared. Their optical properties were studied by a ultraviolet-vis spectrophotometer and a fluorescence spectrophotometer. Structural analysis revealed that the crystal size of ZnO crystallites is <20 nm, and the leached SiO2 nanowires were amorphous. TEM analysis showed that the size of ZnO particles in SZ8 was mainly in the range from 15 to 20 nm and dispersed uniformly on the surface of SiO2 nanowires. The photoluminescence spectra showed that ZnO/SiO2 composites have stronger emitting intensity at the blue–green band than pure ZnO synthesized under the same reaction conditions. Therefore, the composites will be of great interest in the application of luminescence material. The as-prepared ZnO/SiO2 composites can be used as photocatalysts for waste water treatment because they separate much more easily away from solution.  相似文献   

13.
In this work, we have prepared Co‐doped ZnO nanocomposites by zinc nitrate and cobalt sulfate as new precursors via the coprecipitation method and the samples were followed to identify the morphological, optical, structural, and magnetic properties. The XRD patterns revealed the crystalline nature of nanoparticles with hexagonal wurtzite structures, which meant that Co impurity did not disturb the structure of pure ZnO and the minimum crystallite size of nanoparticles was calculated to be around 37 nm. The XRD patterns also showed the lattice parameter increase owing to the incorporation of a Co dopant. The TEM results revealed the sphere‐like particles whose size varied between 56 and 88 nm in diameter at a 4% level of impurity. DRS analysis identified that the band gap energy decreased from 3.18 eV for the pure substance to 2.36 eV for the 10% impure substance. VSM analysis exhibited that the saturation magnetization value increased to 8.4 × 10?3 emu/g for the highest Co content of 10%, which indicated the ferromagnetic behavior of NPs.  相似文献   

14.
In this study, the nanocomposite films of polyvinylidene fluoride/copper nanoparticles were prepared by mixing of copper nanoparticles in a solution of dimethylformamide and polyvinylidene fluoride. The prepared nanocomposites were investigated by fourier transform infrared spectroscopy and X-ray diffraction techniques, showed an obvious α- to β-phase transformation compared to pure PVDF. Scanning electron microscope micrographs showed spherulitic crystal structure of PVDF. The spherulitic morphology of the pure PVDF is maintained for the PVDF nanocomposites; the size of the spherulites decreased by increasing weight fraction of copper nanoparticles. The optical band gap values deduced from the UV–Visible absorption spectra were found to reduce from 4.77 eV in pure PVDF to 3.2 eV after embedding 1 wt% of copper nanoparticles. The surface resistivity values were decreased with increasing copper nanoparticles content. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to pure PVDF.  相似文献   

15.
Silver doped zinc oxide (Ag–ZnO) thin films were deposited on glass and tin doped indium oxide (ITO) coated glass substrates by using pneumatic spray pyrolysis technique (SPT) at 450 °C from aqueous solutions of zinc acetate and silver nitrate precursors. The effect of silver doping on structural, morphological and optical properties of films was studied. The XRD spectra of the Ag–ZnO films indicate the polycrystalline nature having hexagonal crystal structure. SEM micrographs show the uniform distribution of spherical grains of about 80–90 nm grain size for the pure ZnO thin films. The Ag nanoparticles are clearly visualized in SEM images of Ag–ZnO samples. The optical band gap energy decreases as the percentage of silver doping increases. Surface Plasmon Resonance (SPR) related phenomena are observed and correlated to the optical properties of Ag–ZnO thin films. The overall photoelectrochemical (PEC) performance of the samples was investigated and discussed. Moreover, the samples are more photoactive as compare to the pure ZnO sample and the sample ZnOAg15 shows the highest current. The photocurrent increases upto 249 μA cm−2 and 303 μA cm−2 in visible light and in UV illumination, respectively, and then decreases as the Ag doping increases into the film.  相似文献   

16.
张帅国  米杰  尚素利  上官炬  武蒙蒙 《化工进展》2014,33(3):710-713,719
以乙酸锌和草酸为原料,采用低热固相化学反应法制备纳米氧化锌的前体,通过微波和马弗炉两种焙烧方式焙烧制备得到纳米氧化锌,考察了焙烧温度和时间对纳米氧化锌粒径的影响。使用透射电镜、热重-差热、傅里叶变换红外光谱仪和X射线衍射仪对前体和纳米ZnO进行表征;采用晶粒生长动力学唯象理论计算得出纳米氧化锌在这两种焙烧方式下的晶粒生长动力学规律。结果表明,前体为ZnC2O4?2H2O,随着焙烧温度的提高,纳米氧化锌晶粒迅速长大,在相同焙烧温度和时间下,微波焙烧氧化锌的晶粒尺寸要明显大于常规焙烧方式。微波焙烧和常规焙烧下氧化锌的晶粒生长平均动力学指数分别是6.114和6.858,晶粒生长的平均活化能分别为70.67 kJ/mol和52.13 kJ/mol。  相似文献   

17.
ZnO–polyaniline nanocomposite with core–shell nanostructure was prepared by in situ polymerization of aniline monomer in the presence of ZnO nanoparticles. Fourier transform infrared spectroscopy, X-ray diffraction patterns, field emission scanning electron microscopy and transmission electron microscopy techniques were used to characterize the composition and structure of ZnO–polyaniline nanocomposite. d.c. electrical conductivity measurement showed that the electrical conductivity of ZnO–polyaniline nanocomposite pellets is higher than that of pristine polyaniline and ZnO nanoparticles pellets. The addition of ZnO nanoparticles causes to the increasing of polyaniline electrical conductivity. ZnO–polyaniline nanocomposite was mixed with polyvinyl chloride (PVC) through a solution mixing method and the three components PVC/ZnO–polyaniline hybrid material was applied as coating on iron coupon by the solution casting method. Corrosion protection efficiency of PVC/ZnO–polyaniline hybrid coating on iron coupons was studied by open circuit potential and Tafel techniques in 3.5% NaCl solution as corrosive environment. According to the results, PVC/ZnO–polyaniline hybrid nanocomposite coating showed dramatically increased corrosion protection effect on iron samples compared to that of uncoated iron coupon and pure polyaniline anticorrosive coating. It was found that ZnO nanoparticles improve the barrier and electrochemical anticorrosive properties of polyaniline and the addition of polyvinyl chloride increases the barrier effect of polyaniline coating.  相似文献   

18.
In the present investigation, a novel chiral poly(amide-imide) (PAI) was synthesized via direct polycondensation reaction of chiral diacid monomer with 4,4′-methylene bis(3-chloro-2,6-diethylaniline) in molten tetrabutylammonium bromide as a green solvent. Then PAI-based bionanocomposites (BNC)s have been successfully prepared via ultrasonic irradiation method using zinc oxide (ZnO) nanoparticles functionalized by γ-aminopropyltriethoxysilane as a coupling agent to decrease aggregation of nanoparticles in polymer matrix. The physicochemical and morphology properties of the neat PAI and BNCs were studied using 1H-NMR, FT-IR spectroscopy, specific rotation, elemental analysis, X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR and TEM depicted that the ZnO nanoparticles function as a physical cross-linking agent with PAI through hydrogen bonding between the OH on the ZnO nanoparticles and the C=O of the amide and imide groups. Also, TEM and FE-SEM images revealed that ZnO nanoparticles were dispersed in PAI matrix with particle size between 15 and 25 nm. Thermogravimetric analysis data showed an improvement of thermal stability of new BNCs in comparison with the pure PAI.  相似文献   

19.
Nanoparticles of zinc oxide and of ZnO doped with MgO in different concentrations (1, 2 and 4 mol%) were synthesized in a controlled and reproducible way, using the Pechini polymer precursor method. To determine the physicochemical and structural characteristics of the synthesized nanoparticles, Fourier transform IR (FTIR), X-ray diffraction (XRD), UV–Vis spectroscopy and transmission and scanning electron microscopy (TEM and SEM) were used. Characterization revealed the particles obtained to be nanometric in size (<50 nm) and with a deformed hexagonal morphology. Taking into account the doping percentage, the energy gap value varied between 3.3 eV for pure ZnO and 3.45 eV for ZnO with 4 mol% of Mg, which indicates that the optical properties of these nanoparticles were affected by dopant concentration. The effect of doping with Mg2+ on the capacity for removal of pollutant molecules by ZnO, for different working conditions, was evaluated by studying the removal of methyl orange (MO) in aqueous solution. Irradiation of the compounds led to a greater removal of MO from the solution such that all ZnO samples doped with MgO showed higher photoactivity than ZnO. The ZnO nanoparticles doped with 2% Mg were the most efficient in removing MO, achieving a removal percentage of ~73% after 2 h of testing and a totally transparent solution after 3 h of treatment. The kinetics of removal of MO promoted by this sample was best represented by pseudo-first-order kinetics. The results of this work showed that on combining a photosensitive semiconductor, ZnO, with a wide band gap insulator, MgO, Zn–Mg solid solutions are obtained that showed adequate capacity to remove contaminating organic molecules, specifically MO.  相似文献   

20.
Poly (vinyl chloride), PVC, and poly(vinylidene fluoride), PVDF, are incompatible polymers. Poly(neopentyl glycol adipate), PDPA, is miscible with both PVC and PVDF. With PDPA acting as a compatibilizer between PVC and PVDF. compatible PVC/PDPA/PVDF blends can be formed at PVDF content of about less than 50wt%. Above 50wt% PVDF the ternary blends exist in two phases exhibiting two glass transition temperatures, Tg, PVC is the main contributor to the mechanical strength while PDPA and PVDF contribute to the elastic properties of these blends. A compatible blend of 55/22.5/22.5 wt% PVC/PDPA/PVDF exhibiting one single Tg appears to show an interesting balance of the properties of the blend components.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号