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石墨-FeNi核-壳结构复合微球的制备 被引量:1
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作者 李东红 陈栋 +2 位作者 李旺兴 沈湘黔 景茂祥 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2007年第4期728-731,共4页
以硫酸亚铁、硫酸镍、碳酸钠和石墨微球为主要原料,利用非均相成核工艺制备出水合氧化铁和碱式碳酸镍均匀包覆石墨的前驱体微球;通过对前驱体进行热还原处理得到了晶粒约为50nm的γ-FeNi合金颗粒层包覆石墨的产物微球。利用SEM,EDS,XRD... 以硫酸亚铁、硫酸镍、碳酸钠和石墨微球为主要原料,利用非均相成核工艺制备出水合氧化铁和碱式碳酸镍均匀包覆石墨的前驱体微球;通过对前驱体进行热还原处理得到了晶粒约为50nm的γ-FeNi合金颗粒层包覆石墨的产物微球。利用SEM,EDS,XRD对前驱体和产物的形貌、成分、物相分别进行了表征,并利用TG/DSC对前驱体热分解过程进行了分析。通过研究,得出了制备这种核-壳结构复合微球的优化工艺参数。 展开更多
关键词 石墨微球 铁镍 非均相成核 核-壳结构
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Fabrication of magnetic nanosized γ-FeNi-coated ceramic core-shell microspheres by heterogeneous precipitation and thermal reduction 被引量:1
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作者 Donghong Li Jianxin Zhou +1 位作者 Xiangqian Shen Wei Liu 《Particuology》 SCIE EI CAS CSCD 2010年第3期257-261,共5页
Precursors with NiCO3-2Ni(OH)2.2H2O- and Fe203.nH20-coated alumina, graphite and cenosphere were synthesized by precipitation using ferrous sulfate, nickel sulfate, ammonium bicarbonate, alumina, graphite and cenosp... Precursors with NiCO3-2Ni(OH)2.2H2O- and Fe203.nH20-coated alumina, graphite and cenosphere were synthesized by precipitation using ferrous sulfate, nickel sulfate, ammonium bicarbonate, alumina, graphite and cenosphere as the main starting materials. Magnetic γ-FeNi-coated alumina, graphite and cenosphere core-shell structural microspheres were subsequently prepared by thermal reduction of the as-prepared precursors at 600℃ for 2 h. Precipitation parameters, e.g. concentration of ceramic micropowders (lOg/L), sulfate solution (0.2mol/L), rate of adding reactants (3 mL/min) and pH value were optimized by a trial-and-error method. Powders of the precursors and the resulting coating of γ-FeNi with grain size below 40 nm on alumina, graphite and cenosphere microspheres were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The magnetic properties of the nanosize γ-FeNi-coated alumina, graphite and cenosphere microspheres were measured by vibrating sample magnetometer (VSM). The results show that the core-shell structural γ-FeNi-coated ceramic microspheres exhibited higher coercivity than pure γ-FeNi powders, indicating that these materials can be used for high-Derformance functional materials and devices. 展开更多
关键词 Heterogeneous precipitation Core-shell structure γ-feni-coated Magnetic property
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FeNi/SiO_2核-壳纳米球的制备及磁学性质
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作者 彭坤 尹晓建 金晖 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2009年第9期55-58,共4页
利用共沉淀结合氢气还原法制备球形核-壳结构的γ-FeNi/SiO2纳米复合材料.用X射线衍射(XRD)确定样品的相组成,用透射电子显微镜(TEM)观察样品的形貌,用振动样品磁强计(VSM)测定样品的磁性能.结果表明:pH值是影响核-壳纳米结构形貌的重... 利用共沉淀结合氢气还原法制备球形核-壳结构的γ-FeNi/SiO2纳米复合材料.用X射线衍射(XRD)确定样品的相组成,用透射电子显微镜(TEM)观察样品的形貌,用振动样品磁强计(VSM)测定样品的磁性能.结果表明:pH值是影响核-壳纳米结构形貌的重要因素;pH值为9左右且还原温度为700℃,制备出的纳米粒子具有近似的球形核-壳结构:纳米颗粒是以γ-FeNi合金为核心,其平均粒径大约为80 nm,外面包覆非晶SiO2壳层的核-壳结构;随着SiO2质量分数增加,样品的饱和磁化强度明显下降.随着还原温度升高,纳米粒子的尺寸大小略有增加,其饱和磁化强度明显增大,但矫顽力下降,这主要归结于铁镍与铁镍氧化物界面存在交换耦合相互作用. 展开更多
关键词 磁学性能 γ—FeNi/SiO2 核-壳纳米球 共沉淀法
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