中国物理B ›› 2007, Vol. 16 ›› Issue (12): 3837-3842.doi: 10.1088/1009-1963/16/12/047

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Microstructure and magnetic characteristics of nanocrystalline Ni0.5Zn0.5 ferrite synthesized by a spraying--coprecipitation method

丘 泰1, 刘 银2   

  1. (1)College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China; (2)College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China;Department of Materials Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
  • 出版日期:2007-12-20 发布日期:2007-12-20
  • 基金资助:
    Project supported by the National Defence Foundation of China.

Microstructure and magnetic characteristics of nanocrystalline Ni0.5Zn0.5 ferrite synthesized by a spraying--coprecipitation method

Liu Yin(刘银)a) b) † and Qiu Tai(丘泰)a)   

  1. a College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China; b Department of Materials Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
  • Online:2007-12-20 Published:2007-12-20
  • Supported by:
    Project supported by the National Defence Foundation of China.

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摘要： Nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite with average grain sizes ranging from 10 to 100~nm is prepared by using a spraying--coprecipitation method. The results indicate that the nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite is ferromagnetic without the superparamagnetic phenomenon observed at room temperature. Specific saturation magnetization of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite increases from 40.2 to 75.6 emu/g as grain size increases from 11 to 94nm. Coercivity of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite increases monotonically when $d < 62$~nm.The relationship between the coercivity and the mean grain size is well fitted into a relation $H_{\rm c }\sim d^{3}$. A theoretically evaluated value of the critical grain size is 141nm larger than the experimental value 62nm for nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite. The magnetic behaviour of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite may be explained by using the random anisotropy theory.

Abstract: Nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite with average grain sizes ranging from 10 to 100~nm is prepared by using a spraying--coprecipitation method. The results indicate that the nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite is ferromagnetic without the superparamagnetic phenomenon observed at room temperature. Specific saturation magnetization of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite increases from 40.2 to 75.6 emu/g as grain size increases from 11 to 94nm. Coercivity of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite increases monotonically when $d < 62$ nm.The relationship between the coercivity and the mean grain size is well fitted into a relation $H_{\rm c }\sim d^{3}$. A theoretically evaluated value of the critical grain size is 141nm larger than the experimental value 62nm for nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite. The magnetic behaviour of nanocrystalline Ni$_{0.5}$Zn$_{0.5}$ ferrite may be explained by using the random anisotropy theory.

Key words: nanocrystalline material, Ni$_{0.5}$Zn$_{0.5}$ ferrite, spraying--coprecipitation method, magnetic properties

中图分类号:  (Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots))

  • 61.46.Df
75.50.Cc (Other ferromagnetic metals and alloys) 75.50.Gg (Ferrimagnetics) 75.50.Tt (Fine-particle systems; nanocrystalline materials) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects)