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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (20): 2457-2464. 上一篇    下一篇

研究论文

Li0.5－0.5xZnxFe2.5－0.5xO4纳米纤维的电纺制备及其结构和磁性能

向军*,1,2，褚艳秋1，周广振1，郭银涛1，郭纪源1，沈湘黔2   

  1. (1江苏科技大学数理学院 镇江 212003)
    (2江苏大学材料科学与工程学院 镇江 212013)
  • 投稿日期:2011-05-02 修回日期:2011-06-23 发布日期:2011-06-30
  • 通讯作者: 向军 E-mail:junx93@sina.com
  • 基金资助:

    高等学校博士学科点专项科研基金;江苏省普通高校研究生科研创新计划

Electrospinning Preparation, Structural and Magnetic Properties of Li0.5－0.5xZnxFe2.5－0.5xO4 Nanofibers

Xiang Jun*,1,2 Chu Yanqiu1 Zhou Guangzhen1 Guo Yintao1 Guo Jiyuan1 Shen Xiangqian2   

  1. (1 School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003)
    (2 School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013)
  • Received:2011-05-02 Revised:2011-06-23 Published:2011-06-30

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以聚乙烯吡咯烷酮、硝酸锂、硝酸锌和硝酸铁为主要原料, 通过静电纺丝技术结合后期的热处理制备了直径在50～100 nm的单相Li0.5－0.5xZnxFe2.5－0.5xO4 (x＝0.0, 0.2, 0.3, 0.4, 0.5, 0.8)纳米纤维. 利用热重-差热分析、X射线衍射、场发射扫描电子显微镜、透射电子显微镜和振动样品磁强计研究了前驱体纤维的热分解过程以及焙烧温度和化学成分对所得纳米纤维样品的晶体结构、微观形貌和磁性能的影响. 结果表明: 前驱体纤维经350 ℃焙烧后, 纯相晶态的LiZn铁氧体纳米纤维基本形成. 当焙烧温度由350 ℃升高到600 ℃, Li0.35Zn0.3 Fe2.35O4纳米纤维的平均晶粒尺寸由13.0 nm增大到47.5 nm, 微观形貌逐渐向链状结构演化, 比饱和磁化强度由39.7 A•m2•kg－1单调递增到84.5 A•m2•kg－1, 而矫顽力先增大后减小, 在550 ℃时达到最大值12.6 kA•m－1, 其单畴临界尺寸约为35 nm. 随着Zn含量x的增加, 所制备的LiZn铁氧体纳米纤维的晶格常数近似呈线性增长, 符合Vegard定律, 矫顽力从x＝0.0时的17.1 kA•m－1逐步减小到 x＝0.8时的2.4 kA•m－1, 比饱和磁化强度Ms先增大后减小, 在x＝0.3时达到一个最大值74.7 A•m2•kg－1. 与相似条件下制备的LiZn铁氧体纳米粒子相比, LiZn铁氧体纳米纤维由于其形状各向异性, 而表现出相对较高的矫顽力.

关键词: LiZn铁氧体, 纳米纤维, 静电纺丝, 磁性能, 形状各向异性

Single-phase Li0.5－0.5xZnxFe2.5－0.5xO4 (where x＝0.0, 0.2, 0.3, 0.4, 0.5 and 0.8) nanofibers with diameters of 50～100 nm were successfully fabricated via electrospinning technique in combination with subsequent heat treatment using polyvinylpyrrolidone, nickel nitrate, zinc nitrate and ferric nitrate as principal raw material. The thermal decomposition process of as-spun precursor nanofibers and the influences of the calcination temperature and chemical composition on the crystal structure, micromorphology and magnetic properties of the prepared nanofiber samples were investigated by means of thermogravimetric and differential thermal analysis, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer. The results indicate that the pure crystalline LiZn ferrite nanofibers are basically formed when the precursor nanofibers are calcined at 350 ℃ for 2 h. As the calcination temperature increases from 350 to 600 ℃, the average grain size of Li0.35Zn0.3Fe2.35O4 nanofibers ranges from 13.0 to 47.5 nm and the micromorphology evolves toward a chain-like structrue. The saturation magnetization of the samples monotonously increases from 39.7 to 84.5 A•m2•kg－1, while the coercivity increases initially, reaches a maximun value of 12.6 kA•m－1 at 550 ℃ and then decreases, which reveals that the magnetic single-domain critical size of Li0.35Zn0.3Fe2.35O4 nanofibers may be around 35 nm. The lattice constant of as-prepared Li0.5－0.5xZnxFe2.5－0.5xO4 nanofibers calcined at 500 ℃ for 2 h exhibits an almost linear increase with increasing x and complies with Vegards law. The coercivity of these nanofiber samples gradually decreases from 17.1 kA•m－1 for x＝0.0 to 2.4 kA•m－1 for x＝0.8, and the saturation magnetization firstly increases to 74.7 A•m2•kg－1 with the value of x up to 0.3 and then decreases beyond this limit. Compared to the nanoparticle counterparts prepared under similar conditions, the LiZn ferrite nanofibers have a relatively high coercivity due to their large shape anisotropy. These LiZn ferrite nanofibers have potential application in many fields such as nanoelectronic devices, sensitive devices, microwave absorbers, and biomedicine.

Key words: LiZn ferrite, nanofiber, electrospinning, magnetic properties, shape anisotropy

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