采用溶胶-凝胶法及在氢气中还原的工艺制备了纳米FeCo/Al_2O_3复合材料. 利用X射线衍射、透射电镜、振动样品磁强计和M(o)ssbauer谱学对样品微观结构和磁性进行了研究. 结果表明: 纳米FeCo/Al_2O_3复合材料中的FeCo合金为体心立方结构;随着还原温度的提高, α-FeCo合金晶粒尺寸变大, Al_2O_3的存在有效地抑制了a-FeCo合金晶粒的团聚和生长;随着α-FeCo合金晶粒尺寸的变大, 样品的比饱和磁化强度增加, 而矫顽力先增大后减小, 两者分别在1100℃和1000℃时达到最大值62. 41 emu·g~(-1)和208. 99 Oe, FeCo/Al_2O_3由超顺磁和磁有序的混合状态转变为完全的磁有序状态;矫顽力的变化是由于FeCo合金的磁学结构由单磁畴结构转变为多磁畴结构造成的.
Nano FeCo/Al2O_3 composites were synthesized using a sol-gel technique combined with H_2 reduction method. The microstructnre and magnetic properties of the samples were characterized by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer and M(o)ssbauer spectroscopy. The results show that nano FeCo in FeCo/Al_2O_3 composites presents bcc structure. With the increasing of reducing temperature, the grain size of FeCo increases, while glomeration and growth of α-FeCo are restricted effectively due to the existence of Al_2O_3. With the increasing of the grain size of FeCo, the saturation magnetization of the samples increases, but the coercivity of the samples increases firstly then decreases. The maximum values of saturation magnetization and coercivity are 62. 41 emu·g~(-1) and 208. 99 Oe respectively; FeCo/Al_2O_3 transforms from a mixed state containing superparamagnetism and magnetic-order to a complete magnetic-order state. The change of coercivity results from the transformation of magnetic structure from single-domain to multi-domain.
参考文献
| [1] | Paesano J A,Matsuda C K,DaCunha J B M,et al.Synthesis and characterization of Fe-Al_2O_3 composites[J].Journal of Magnetism and Magnetic Materials,2003,264(2/3):264-274. |
| [2] | Carta D,Mountjoy G,Gass Mt et al.Structural characterization study of FeCo alloy nanoparticles in a highly porous aerogel silica matrix[J].Journal of Chemical Physics,2007,127(20):204705-204713. |
| [3] | Stefano C,Luca M,Plinio I,et al.Confined growth of iron cobalt nanocrystals in mesoporous silica thin films:FeCo-SiO_2 nanocomposites[J].Mieroporous and Mesoporous Materials,2008,115(3):338-344. |
| [4] | Tang G D,Hou D L.Zhang M,et al.Influence of preparing condition on magnetic properties of the FeCoNi-SiO_2 granular alloy solids[J].Journal of Magnetism and Magnetic Materials,2002,215(1):42-49. |
| [5] | Girl A K.Magnetic properties of Fe-Al_2O_3 gel granular solids prepared by ball milling[J].Journal of Applied Physics,1997.32(5):523-529. |
| [6] | Lu X G,Liang G Y,Zhang Y M.Structure and magnetic properties of FeCo-SiO_2 nanocomposite synthesized by a novel wet chemical method[J].Materials Letters,2007,61(27):4928-4931. |
| [7] | 张伯军,陈敬艳,刘梅,等.热处理温度对纳米CoFe_2O4_/SiO_2复合材料结构和磁性的影响[J].复合材料学报,2008,25(3):144-148.Zhang Bojun,Chen Jingyan,Liu Mei,et al.Influence of heat treat temperature on structure and magnetic properties of CoFe_2O4_/SiO_2 nanocomposite[J].Acta Materiae Compositae Sinica,2008,25(3):144-148. |
| [8] | Liu X X,Morisako A.Soft magnetic properties of FeCo films with high saturation magnetization[J].Journal of Applied Physics,2008.103(7):07E726(1-3). |
| [9] | Zele(n)ākovā A,Olek(s)ākovā D,Degmovā J,et al.Structuraland magnetic properties of mechanically alloyed FeCo powders[J].Journal of Magnetism and Magnetic Materials.2007,316(2):e519-e522. |
| [10] | Schneeweissa O,David B,Zak T,et al.Nanocrystalline Fe-Ni and Fe-Co samples prepared by powder processing[J].Journal of Magnetism and Magnetic Materials,2007,310(2):e858-e860. |
| [11] | Li F S,Zhou D,Wang T,et al.Fabrication and magnetic properties of FeCo alloy nanotube array[J].Journal of Applied Physics,2007,101(1):014309(1-3). |
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