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Acta Chimica Sinica ›› 2011, Vol. 69 ›› Issue (20): 2457-2464. Previous Articles Next Articles
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向军*,1,2,褚艳秋1,周广振1,郭银涛1,郭纪源1,沈湘黔2
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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
Xiang Jun*,1,2 Chu Yanqiu1 Zhou Guangzhen1 Guo Yintao1 Guo Jiyuan1 Shen Xiangqian2
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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
CLC Number:
O611.6
XIANG Jun, CHU Yan-Qiu, ZHOU Guang-Zhen, GUO Yin-Tao, GUO Ji-Yuan, SHEN Xiang-Qian. Electrospinning Preparation, Structural and Magnetic Properties of Li0.5-0.5xZnxFe2.5-0.5xO4 Nanofibers[J]. Acta Chimica Sinica, 2011, 69(20): 2457-2464.
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