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微波辐射乳液聚合制备磁性高分子微球 总被引:1,自引:0,他引:1
用化学共沉淀法制备了Fe3O4纳米粒子,并用油酸和十二烷基硫酸钠对Fe3O4纳米粒子进行表面修饰,得到了稳定的水分散性纳米Fe3O4磁流体。在Fe3O4磁流体存在下,以苯乙烯和丙烯酰胺为单体,采用微波辐射乳液聚合法制备了Fe3O4/聚(苯乙烯-丙烯酰胺)磁性高分子微球,表征了磁性高分子微球的形态与结构,研究了磁性高分子微球的粒径、热稳定性、磁含量与饱和磁化强度。研究发现,在选定合适的聚合条件下,通过微波辐射乳液聚合法可以制得粒径为70 nm~80 nm、磁含量为18.2%的磁性高分子微球。 相似文献
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以钢厂副产的氧化铁红作为含铁原料,采用微波辅助熔盐法制备了SrFe12O19铁氧体,研究了Fe/Sr摩尔比和微波煅烧温度对样品的物相组成、微观结构及磁性能的影响。采用FullProf软件对样品的XRD数据进行了精修拟合分析,利用扫描电子显微镜(SEM)观察了样品的形貌,用振动样品磁强计(VSM)对样品的磁性能进行了表征。结果表明,Fe/Sr摩尔比对样品的物相组成及样品的晶胞参数有重要影响,当Fe/Sr摩尔比为10.5时,样品获得了较好的磁性能。随着煅烧温度的增加,SrM相的厚度也随着增加,在1373.15 K下微波煅烧2 h, SrM相的厚度最大,此时样品矫顽力最大达到2.69×105 A/m,饱和磁化强度为63.04 A·m2/kg,而在1273.15 K制备的样品最大磁能积最大为9.47×103 J/m3。 相似文献
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用纳米Fe3O4磁性粉末作为载体,负载α-二亚胺N i催化剂制得磁性纳米催化剂。通过乙烯在纳米催化剂粒子表面原位聚合得到既不同于结构型磁性材料也不同于普通复合型磁性材料的一种新型磁性支化聚乙烯材料。 相似文献
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纳米磁性多层膜的微波电磁特性研究 总被引:5,自引:1,他引:5
采用射频磁控溅射法制备了FeCoB/SiO2纳米磁性多层膜,并对其微波特性进行研究。用微波谐振腔法测量了该薄膜的复磁导率.2GHz频率处复磁导率实部及虚部分别可达251和22.7。重点研究了多层膜结构中介质层厚度及薄膜总厚度对磁导率的影响,同时结合直流电阻率ρ、静态磁参数Bs、Hc的测量结果分析.探讨了纳米磁性多层膜的微波高磁导率机理.并提出了微波频率下获得高磁导率及低磁损耗的途径。实验结果也表明这种纳米磁性多层膜材料有望在高频平面变压器、平面电感器、薄膜电磁干扰抑制器等领域获得应用。 相似文献
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通过化学共沉淀法制备Fe3O4纳米粒子,再用油酸钠和十二烷基磺酸钠(SDS)对Fe3O4进行改性,制得稳定的水基磁流体。在自制的磁流体存在下,以氰基丙烯酸正丁酯(BCA)为单体,用微波辐射乳液聚合的方法制备了Fe3O4/聚氰基丙烯酸正丁酯磁性微球。并用X射线衍射仪(XRD),透射电子显微镜(TEM),傅立叶红外光谱仪(FT-IR),振动样品磁强计(VSM)对制备的磁性高分子微球的结构形貌和磁性能进行表征测试。结果表明,在适当的pH值条件下,得到了粒径为150 nm~200 nm,饱和磁化强度为20.23 emμ/g,粒径均一的聚氰基丙烯酸正丁酯磁性微球。 相似文献
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以硝酸铟作为铟源,用硫代乙酰胺或者2-甲基硫代丙酰胺为硫源,在低温开放系统中采用微波辅助加热制备得到硫化铟(In_2S_3)微球。分别采用包括表面光电压谱(SPV)及紫外-可见漫反射(DRS)在内的诸多方法对产物进行表征,并探究了不同硫源及pH值对In_2S_3的结构、尺寸及光学性质的影响。以硫代乙酰胺作为硫源时,微波温度90℃下,制备得到实心In_2S_3微球;以2-甲基硫代丙酰胺为硫源时,微波温度85℃下,制备得到空心In_2S_3微球。空心In_2S_3微球的表面光电压高于实心,说明空心In_2S_3微球的光激发电荷分离效率优于实心。 相似文献
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Nanocrystalline nickel ferrite has been successfully synthesized through a simple hydrothermal process at 180 °C for 10 h. The as-synthesized powders were characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. TEM image and HRTEM image revealed that the as-prepared crystals were well crystallized with grain size distribution from 50 to 80 nm. The magnetic properties were studied by vibrating sample magnetometer (VSM), it exhibited lower coercivity and higher saturation magnetization which came from high crystallinity and uniform morphologies. 相似文献
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CoPt nanoparticles with an average size of 3?nm and narrow distribution were synthesized by chemical reduction of Co(CH(3)COO)(2) and Pt(acac)(2) by polyethyleneglycol-200. The as-prepared nanoparticles have a disordered fcc structure which transformed after thermal treatment to an ordered fct structure, which results in coercivity up to 6?kOe at room temperature and 9?kOe at 5?K because of the high magnetocrystalline anisotropy of the tetragonal structure [Formula: see text]. 相似文献
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Using the polyol method and a thermal post-treatment, nanoporous tin dioxide (SnO2) were prepared at different hydrolysis ratio (h = n (H2O)/n (Sn)). The influence of the hydrolysis ratio on the structural, textural, optical and electrical properties of SnO2 nanopowders was investigated by employing a set of various techniques including Fourier Transform Infra-Red spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Nitrogen Sorption Porosimetry and Impedance Spectroscopy. FTIR and EDX studies revealed that SnO2 species were obtained. Nanocrystallites of cassiterite, i.e. rutile-like tetragonal SnO2 structure, were formed after annealing in air at 700 °C and the average crystallite size increased from 12.8 to 29.1 when the hydrolysis ratio rose from 17 to 24. Moreover, TEM, SEM, and N2 sorption porosimetry investigations indicated that the sample prepared for h = 17 was composed of an aggregated network of almost spherical nanoparticles, the morphology and sizes of which changed with the increase in the hydrolysis ratio to h = 24 and the mesoporosity of which was found to be linked to the interparticle space. Moreover, this increase in mean nanoparticle size was accompanied by a decrease in the band gap value from 3.4 eV (h = 17) to 3.16 eV (h = 24). Finally, bulk conductivity dependence with temperature was found to follow an Arrhenius law for samples annealed at 700 °C with an activation energy of 0.65 eV for h = 17, 0.69 eV for h = 20 and 0.71 eV for h = 24 that is typical of SnO2 nanopowders. 相似文献
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采用多元醇法在150~190℃合成了CoNi合金纳米粒子,利用SEM-EDX,XRD和VSM对所制备的CoNi纳米粒子形貌、成分、结构以及磁性能进行了研究,并进一步探讨了形核剂K2PtCl4对CoNi纳米粒子形貌及磁性能的影响。结果表明,在180℃用多元醇法制备的Co40Ni60(inat%)纳米粒子为FCC结构,Co2+要易于Ni2+被还原,导致最初10min内合成的CoNi纳米粒子中含有约78%(原子分数)Co,表现为高饱和磁化强度和高矫顽力,随着反应时间的延长,CoNi纳米粒子的Co含量、饱和磁化强度及矫顽力逐步下降。在150~190℃范围内,随着反应温度的提高,Ni2+的被还原能力增强,高温下合成的CoNi纳米粒子具有较低的饱和磁化强度和较小的矫顽力。形核剂K2PtCl4的加入,并不影响CoNi合金纳米粒子的成分和晶体结构。但是,随着形核剂浓度的增加,CoNi纳米粒子平均直径明显减小,其矫顽力有所增大。通过设计形核剂的浓度,CoNi纳米粒子的直径可以在96~580nm范围内任意控制。 相似文献
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Liu T Zhang G Su X Chen X Wang D Qin J 《Journal of nanoscience and nanotechnology》2007,7(7):2500-2505
A microwave-assisted monosaccharide reducing approach has been developed in the preparation of tellurium nanotubes. The as-prepared tellurium nanotubes have the sizes of 50 - 100 nm in diameter, and a few micrometers in length. A series of contrastive experiments have illustrated that microwave-heating contributed a lot in the synthesis, and the decomposition of H2TeO3 to TeO2 and low reducibility of the monosaccharide played a key role in the process. The possible mechanism of the synthesis of the nanotubes has been preliminarily discussed. 相似文献
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Qin GW Pei WL Ren YP Shimada Y Endo Y Yamaguchi M Okamoto S Kitakami O 《Journal of nanoscience and nanotechnology》2011,11(12):10796-10799
Ni80Fe20 permalloy nanoparticles with narrow size distribution and homogeneous composition have been prepared by the polyol processing at 180 degrees C for 2 h and their particle sizes can be tunable in the size range of 20-440 nm by proper addition of K2PtCI4 agent. X-ray diffraction results show that the NiFe nanoparticles are of face centered cubic structure. The addition of K2PtCl4 does not affect the composition of NiFe NPs but decreases the particle size remarkably. Both saturation magnetization and coercivity of the as-prepared NiFe nanoparticles decrease with decreasing particle size. Annealed at 280 degrees C, however, the saturation magnetization of various sized NiFe nanoparticles increases drastically and approaches to the bulk for the -440 nm NiFe particles, and a maximum coercivity (-270 Oe) happens at a critical size of -50 nm. The magnetic property dependency of these NiFe nanoparticles on annealing has been discussed by considering the surface chemistry. 相似文献
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Copper sulfide nanostructured spheres and nanotubes were successfully synthesized, using a microwave-assisted solvothermal method, by the decomposition of [Cu(CH3CSNH2)2]Cl2 complexes, formed by the reaction of CuCl2·2H2O and CH3CSNH2 in ethylene glycol at different pH values, and identified by CHNS/O and FTIR analyses. The decrease in bonding energy of N-H revealed the coordination of copper ions and thioacetamide molecules. It was specified that nitrogen atoms of thioacetamide molecules were used to form Cu-thioacetamide complexes. XRD, SEM, TEM and SAED analyses show that the products were hexagonal CuS spheres in an extremely low pH solution, and hexagonal CuS nanotubes at a pH 13. Their Raman spectra show sharp peaks at 473 cm− 1, identified as the S-S stretching mode of S2 ions at the 4e sites. 相似文献
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Fatemeh Ashrafi Seyyed Mohammad Hassan Feiz Hamid Reza Fallah Mohammad Hassan Yousefi Mohammad Hosein Shivaee 《Journal of Materials Science: Materials in Electronics》2014,25(4):1880-1886
In this paper, zinc selenide nanoparticles powder was successfully synthesized using rapid polyol method. The preparation method was changed by using new Se solvents in the final stage to delete seleniums which have not participated in reaction product. This change in the preparation method increased the purity of final product (92 %); and using selenium’s solvents as detergents caused the production of ZnSe with roughly 100 % purity. X-ray diffractions showed that the samples had a cubic structure with lattice constant equalling 5.6699 Å and with 5.5 nm for crystallite size. Atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) images showed that the particles were almost spherical and well crystallized ZnSe nanoparticles were formed. The average sizes of nanoparticles were 15 and 16.4 nm for AFM and HRTEM, respectively. Absorption Spectra of all samples showed a blue shift in comparison with bulk ZnSe. It showed low absorption in a wide range of wavelengths. Band gap energy of the pure ZnSe nanoparticles was found to be 4.51 eV, which is higher than that of the bulk value of ZnSe (2.67 eV). Photoluminescence spectra of the samples showed emission at 450–500 nm wavelengths at room temperature which are useful for the application of solar cells, quantum dot light-emitting diodes and blue organic light-emitting diodes devices. 相似文献
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Ni1?xFexO (x = 0 and 0.03) nanoparticles are synthesized by a chemical route. XRD and TEM measurements confirm phase purity and crystallinity of the nanoparticles. Fe substitution in NiO reduces considerably the average particle size of the nanoparticles. The pristine NiO sample with size 14 nm and Fe-substituted sample having size 7 nm show room temperature ferromagnetism. The pristine NiO having 31 nm size and Fe-substituted sample with size 25 nm are found to be antiferromagnetic. The M–H and M–T behavior of the pristine and Fe-doped samples are explained with a core–shell model with an antiferromagnetic core and a ferromagnetic shell. The disordered spins at the shell give rise to a spin-glass like frozen state below 10 K. The obtained room temperature ferromagnetism in the pristine and Fe-doped NiO has been attributed to particle size effect. 相似文献