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931.
932.
以乙二醇为溶剂,氯化铁、氯化钴、氯化镍和醋酸铵为反应试剂,采用溶剂热法制备纳米NixCo1-xFe2O4(x=0、0.3、0.5、0.7、1)铁氧体空心微球,研究镍含量对铁氧体空心球的磁性与吸波性能的影响。借助X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、振动样品磁强计(VSM)和网络分析仪对试样的物相组成、微观形貌和电磁特性进行表征。结果表明制备的镍钴铁氧体为尖晶石结构,且形貌为空心球,粒径在200 nm左右。当x=0时,镍钴铁氧体空心球饱和磁化强度最大为81.7 emu·g-1,反射损耗在1 658.8 MHz有最小值为-16.9 dB。 相似文献
933.
将低温水热反应和低温热处理相结合,制备了含还原氧化石墨烯(RGO)、碳纳米管(CNTs)和Co3O4的三元纳米复合材料RGO-CNTs-Co3O4;利用X射线衍射仪、扫描电子显微镜、透射电子显微镜分析了合成产物的相组成和微观结构,分析了其形成过程;并利用电化学测试装置测定了其作为锂离子电池负极材料的电化学性能.结果表明,在合成反应过程中,氧化石墨烯被还原剂肼还原为石墨烯,同时在石墨烯和CNTs表面生成氢氧化钴;再经低温热处理得到RGO-CNTs-Co3O4三元复合材料.Co3O4纳米颗粒均匀分散在由RGO片层和CNTs组成的三维网络结构中;这种三维网络结构既有利于电子和离子的传输,又能够有效抑制Co3O4在脱嵌锂过程中因体积变化引起的结构破坏.总体而言,合成的新型三元复合材料具有高的比容量以及良好的循环性能与倍率性能. 相似文献
934.
Preparation and Characterization of Cyclohexyl Moiety Toughened POSS-Reinforced Epoxy Nanocomposites
Polyhedral oligomeric silsesquioxane (POSS)-reinforced epoxy nanocomposites were prepared by reacting commercially available diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM) epoxy resins with 1,1-bis(3-methyl-4-glycidyloxyphenyl)cyclohexane (Cy-Ep) separately and reinforced with POSS nanocluster. POSS (OAPS)-reinforced hybrid Cy-Ep-epoxy resin castings were characterized for their mechanical and morphological properties. The data obtained from mechanical studies indicated that the incorporation of nano OAPS into Cy-Ep modified hybrid systems results in improved stability. Among the epoxy systems studied, the TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher than that of the TGDDM system. The dispersion of POSS was confirmed by scanning electron microscopy and visual observation studies. 相似文献
935.
H. P. S. Abdul Khalil M. Jawaid P. Firoozian E. S. Zainudin M. T. Paridah 《International Journal of Polymer Analysis and Characterization》2013,18(4):247-256
Nano-activated carbons obtained from oil palm empty fiber bunch (AC-EFB), bamboo stem (AC-BS), and coconut shells (AC-CNS) were reinforced in epoxy matrix to fabricate epoxy nanocomposites. The dynamic mechanical analysis of epoxy nanocomposites was carried out, and 5% AC-CNS treated with KOH-filled epoxy composites displayed the highest storage modulus of all the activated carbon–filled epoxy composites. The incorporation of a small amount of AC-BS, AC-EFB, and AC-CNS to the epoxy matrix enhanced the damping characteristics of the epoxy nanocomposites. The 5% AC-EFB treated with H3PO4 filled epoxy composites showed the highest glass transition temperature (Tg) in all temperature ranges. 相似文献
936.
A solvothermal post‐treatment method was developed to synthesize Fe3O4@mesosilica core–shell nanospheres (CSNs) with a well‐preserved morphology, mesoporous structure, and tunable large pore diameters (2.5–17.6 nm) for the first time. N,N‐Dimethylhexadecylamine (DMHA), which was generated in situ during the heat‐treatment process, was mainly responsible for this pore‐size enlargement, as characterized by NMR spectroscopy. This pore‐size expansion can be strengthened with the aid of hexamethyldisilazane (HMDS), whilst the nature of the surface of the Fe3O4@mesosilica CSNs can be easily modified with trimethylsilyl groups during the pore‐size‐expansion process. The hydrophobicity of the Fe3O4@mesosilica CSNs increased for the enlarged mesopores and the adsorption capacity of these CSNs for benzene (up to 1.5 g g?1) is the highest ever reported for Fe3O4@mesosilica CSNs. The resultant Fe3O4@mesosilica CSNs (pore size: 10 nm) showed a 3.6‐times higher adsorption capacity of lysozyme than those without the pore expansion (pore size: 2.5 nm), thus making them a good candidate for loading large molecules. 相似文献
937.
Two new 3D lanthanide(III)? copper(II) organic frameworks based on unusual {OLn6} clusters have been successfully synthesized and fully characterized. Crystallographic studies showed that the {OLn6} clusters acted as 12‐connected nodes that were linked together by [CuL2] (H2L=3‐hydroxypyrazine‐2‐carboxylic acid) moieties to construct an interesting 4,12‐c net with the point symbol {436.630}{44.62}3. Magnetic studies revealed that these two isostructural heterometallic frameworks exhibited different magnetic properties, depending on the different anisotropies of the lanthanide spin carriers: Gd‐Cu showed a large magnetocaloric effect, with an entropy change (?ΔSm) of 35.76 J kg?1 K?1, which is one of the largest values in high‐dimensional complexes, whilst Dy‐Cu exhibited slow relaxation of the magnetization at low temperatures. 相似文献
938.
Prof. Dr. Minghuey Shieh Chun‐Hsien Yu Yen‐Yi Chu Yu‐Wen Guo Chung‐Yi Huang Kai‐Jieah Hsing Pei‐Chi Chen Chung‐Feng Lee 《化学:亚洲杂志》2013,8(5):963-973
The reactions of E powder (E=S, Se) with a mixture of Cr(CO)6 and Mn2(CO)10 in concentrated solutions of KOH/MeOH produced two new mixed Cr? Mn? carbonyl clusters, [E2CrMn2(CO)9]2? (E=S, 1 ; Se, 2 ). Clusters 1 and 2 were isostructural with one another and each displayed a trigonal‐bipyramidal structure, with the CrMn2 triangle axially capped by two μ3‐E atoms. The analogous telluride cluster, [Te2CrMn2(CO)9]2? ( 3 ), was obtained from the ring‐closure of Te2Mn2 ring complex [Te2Mn2Cr2(CO)18]2? ( 4 ). Upon bubbling with CO, clusters 2 and 3 were readily converted into square‐pyramidal clusters, [E2CrMn2(CO)10]2? (E=Se, 5 ; Te, 6 ), accompanied with the cleavage of one Cr? Mn bond. According to SQUID analysis, cluster 6 was paramagnetic, with S=1 at room temperature; however, the Se analogue ( 5 ) was spectroscopically proposed to be diamagnetic, as verified by TD‐DFT calculations. Cluster 6 could be further carbonylated, with cleavage of the Mn? Mn bond to produce a new arachno‐cluster, [Te2CrMn2(CO)11]2? ( 7 ). The formation and structural isomers, as well as electrochemistry and UV/Vis absorption, of these clusters were also elucidated by DFT calculations. 相似文献
939.
Herein, we present three imidazo[1,2‐a]pyridin‐2(3 H)‐one derivatives that are diamagnetic in solution, but paramagnetic in the solid state, possibly owing to a stacking‐induced formation of phenoxide‐type radicals. Notably, a larger bathochromic shift of the absorption (even up to the near‐ infrared region) of these three compounds was observed in the solid state than in solution, which was attributable to the ordered columnar stacking arrangements or their single‐electron character as radicals in the solid state. Interestingly, compared to that in solution, (E)‐3‐(pyridin‐4′‐ylmethylene)imidazo[1,2‐a]pyridine 2(3 H)‐one displayed a largely red‐shifted emission (centered at 660 nm, with tailing above 800 nm) in the solid state. A larger bathochromic shift (260 nm) of the emission is an indication of better order and tight stacking in the solid state, which is brought about by the rigid and polar acceptor. These three compounds also reveal different magnetic susceptibilities at 300 K, thus implying that they possess various columnar stacking structures. Most interestingly, these three radicals exhibit unusual ferromagnetic‐to‐antiferromagnetic phase transitions, which can be attributed to anisotropic contraction and non‐uniform slippage of the columnar stacking chains. 相似文献
940.
Graphene is a 2D sp2‐hybridized carbon sheet and an ideal material for the adsorption‐based separation of organic pollutants. However, such potential applications of graphene are largely limited, owing to their poor solubility and extensive aggregation properties through graphene? graphene interactions. Herein, we report the synthesis of graphene‐based composites with γ‐Fe2O3 nanoparticle for the high‐performance removal of endocrine‐disrupting compounds (EDC) from water. The γ‐Fe2O3 nanoparticles partially inhibit these graphene? graphene interactions and offer water dispersibility of the composite without compromising much of the high surface area of graphene. In their dispersed form, the graphene component offers the efficient adsorption of EDC, whilst the magnetic iron‐oxide component offers easier magnetic separation of adsorbed EDC. 相似文献