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高能球磨法制备纳米晶Zn铁氧体 总被引:12,自引:0,他引:12
用高能球磨法制备了纳米晶Zn铁氧体。通过样品的Moessbauer谱及XRD谱的测定,研究了纳米晶的形成过程。结果表明:球磨的3hα-Fe2O3即与ZnO发生机械化学反应生成Zn铁氧体,这种反应是通过先形成α-Fe2O3-ZnO固溶体而进行的。制得的纳米晶铁氧体有一定的晶格畸变。 相似文献
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应用化学共沉淀法制备了NiZn铁氧体的前驱体粉末。对前驱体在900℃热处理后,得到尖晶石型NiZn铁氧体样品。用X射线衍射(XRD)和电子扫描显微镜(SEM)对其进行表征,结果表明:样品的晶体形貌为准六角形,粒径大小Dsem≈3.5μm,而Dxrd≈80nm,即Dsem≈44Dxrd这是NiZn铁氧体制备领域一个新颖的结果。采用该方法制备的样品可能具有一定的实用价值与经济价值。 相似文献
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球磨条件对Fe-Ni纳米晶结构和磁性的影响 总被引:7,自引:0,他引:7
用机械合金化方法制备两组Fe100-xNix系纳米晶合金。采用不同的球磨条件:A组样品的球粉质量比为20:1,球磨机的转速为200r/min,对应着较高的球磨能量。B组样品的球粉质量比为14:1,球磨机的转速为160r/min。对应着较低的球磨能量。在相同的球磨时间(60h),不同的球磨能量下得到Fe-Ni系纳米晶合金的不同结构与磁性。前者基本上为单相Ni(FCC)的无序Fe-Ni固溶体而后者为α-Fe(BCC)与γ-Ni(FCC)混相合金。前者基本呈现超顺磁性的磁滞回线而后者却出现了Perminvar效应,吴峰腰形磁滞回线。本文对这些结果进行了讨论。 相似文献
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以LiOH-H2O,Fe2O3和草酸为原料,通过流变相反应,制得草酸盐结构的Li铁氧体前驱体。将前驱体在远低于通常的固相反应的温度下进行热处理,得到Li铁氧体纳米粒子。这一反应通过LiFeO2作为中间相来完成。用XRD和VSM对制得的Li铁氧体粉体进行了表征。结果表明,所得铁氧体为纳米粒子,具有有序结构,且具有较高的饱和磁化强度和矫顽力。纳米晶Li铁氧体粉料表现出良好的微波吸收特性。 相似文献
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我们用PEG凝胶法合成出的LiFe_5O_3纳米晶,用XRD和TEM观测其粒径和形貌。用振动样品磁强计考察其比饱和磁化强度σ_s,随粒径口变化,得到样品的σ_s随D的减小而下降。 相似文献
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对Fe73.5Cu1nb3Si13.5B9成分的母合金进行了机械球磨,并对不同时间的球磨样品进行了X射线衍射(XRD)和Mossbauer谱(MS)的测量,结果表明样品难以完全非晶化,形成了无序的αFe-Si固溶体的纳米晶,晶粒尺寸在5nm左右,同时共存一部分富集Nb,B元素的界面非晶相。在各种球磨条件下对αFe-Si固溶体中的Si含量进行了计算。 相似文献
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为了改善Mg-Ni合金的电化学性能,采用高能球磨技术合成了Mg-Zr-Ni储氢合金,通过改变球磨条件和添加合金元素Zr,利用XRD物相分析和电化学测量技术,研究了Mg-Ni合金的组织演变过程及其对电化学容量的影响.结果表明,高能球磨Mg-Ni和Mg-Zr-Ni合金都经历了非晶态向纳米晶态的转变过程,用少量Zr替代部分Mg后,促进了高能球磨Mg-Zr-Ni合金的非晶化和纳米晶化的过程.与非晶态Mg(Zr)Ni相比,纳米晶的Mg(Zr)Ni中氢更易放出,放电曲线主要呈现高电位放电特征,添加Zr后合金的放电容量有所下降. 相似文献
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为了制备高密度的TiA l基合金,研究了高能球磨Ti/A l复合粉体的烧结性能.冷压坯在660℃以下真空反应烧结,采用排水法测定了烧结坯体积和密度变化,利用X射线衍射、扫描电子显微镜研究了坯料烧结过程中的相变和显微组织特征.结果表明,坯料在低温烧结过程中产生明显的体积膨胀和开裂.原因主要是低密度过渡金属间化合物TiA l3的形成,烧结过程中A l向Ti扩散留下的孔隙,高能球磨和压坯过程中产生的塑性变形以及Ti、A l反应烧结过程中的自蔓燃现象.适当延长球磨时间和严格控制烧结温度将有助于减少膨胀,避免开裂. 相似文献
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Ho Tak Yu Chadrasekhar Loka Kee-Sun Lee Jong Soo Cho Sang Han Lee 《Materials Science and Engineering: B》2013,178(20):1422-1428
Nano-structured composite with overall atomic composition Si60/(FeSiB)40 has been synthesized by high-energy mechanical milling (HEMM) for Lithium-ion rechargeable batteries as anode material. Crystal structure, microstructure, electrochemical properties, elastic modulus and Vickers hardness (HV) have been observed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), electrochemical test and nano-indentation test. With increasing milling time from 6 to 10 h, we observed a relatively homogeneous structure comprised of nano-crystalline active silicon (Si) embedded in less active FeSiB matrix phase. Electrochemical properties of 10 h milled nano-composite powder offers low capacity fade, high coulombic efficiency from 3rd cycle (540 mAh g−1) to until 102nd cycle (495 mAh g−1). The coulombic efficiencies of both 6 and 10 h milled powders are 98% and 99%, respectively. Coin cell cross sections of 6 and 10 h milled powders showed evidence for the void formation during lithiation and delithiation. Nano-indentation results exhibited that the amorphous FeSiB flakes have 2.96 times higher recoverable energy than Si. Resultant composite powders showed high irreversible capacity and stable lithiation and delithiation due to the reduced particle size, increased surface area and the highly elastic FeSiB matrix phase. Research reveals that the obtained nano-composite can be a promising candidate for lithium-ion rechargeable batteries. 相似文献
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Mustafa Baris Tuncay Simsek Telem Simsek Sadan Ozcan Bora Kalkan 《Advanced Powder Technology》2018,29(10):2440-2446
The present work provides a new insight into the high purity synthesis of zirconium diboride (ZrB2) powders and a method of controlling impurity during the synthesis process. The single phase ZrB2 nano-powder was synthesized by a combined ball milling and carbothermal method using zirconium oxide (ZrO2), boron oxide (B2O3) and carbon (C) as starting materials. The reaction pathway, phase purity, and morphology of the ZrB2 produced are elucidated from X-ray diffraction (XRD) and scanning electron microscopy studies. The details of the impure phases generated during synthesis were obtained from multi-phase Rietveld refinements of XRD data. Experiments revealed that the method of synthesis carried out at 1750?°C involving ZrB2:B2O3:C at a molar ratio of 1:4.5:7.5 could produce highly pure ZrB2 nano-powders of 67?nm average crystallite size. The magnetometry studies on such pure form of ZrB2 nano-powders indicated that both paramagnetic and diamagnetic characteristics coexisted in ZrB2, which could be attributed to its polycrystallinity. 相似文献