中国物理B ›› 2010, Vol. 19 ›› Issue (10): 107502-107502.doi: 10.1088/1674-1056/19/10/107502

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Polydispersity effects on the magnetization of diluted ferrofluids: a lognormal analysis

王旭飞, 施立群   

  1. Applied Ion Beam Physics Laboratory, Fudan University, Key Laboratory of the Ministry of Education, Shanghai 200433, China; Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China
  • 收稿日期:2010-01-03 修回日期:2010-04-15 出版日期:2010-10-15 发布日期:2010-10-15
  • 基金资助:
    Project supported by the Shanghai Leading Academic Discipline Project of China (Grant No. B107).

Polydispersity effects on the magnetization of diluted ferrofluids: a lognormal analysis

Wang Xu-Fei(王旭飞)a)b)† and Shi Li-Qun(施立群)a)b)   

  1. Applied Ion Beam Physics Laboratory, Fudan University, Key Laboratory of the Ministry of Education, Shanghai 200433, China; Institute of Modern Physics, Department of Nuclear Science and Technology, Fudan University, Shanghai 200433, China
  • Received:2010-01-03 Revised:2010-04-15 Online:2010-10-15 Published:2010-10-15
  • Supported by:
    Project supported by the Shanghai Leading Academic Discipline Project of China (Grant No. B107).

摘要: Based on a lognormal particle size distribution, this paper makes a model analysis on the polydispersity effects on the magnetization behaviour of diluted ferrofluids. Using a modified Langevin relationship for the lognormal dispersion, it first performs reduced calculations without material parameters. From the results, it is extrapolated that for the ferrofluid of lognormal polydispersion, in comparison with the corresponding monodispersion, the saturation magnetization is enhanced higher by the particle size distribution. It also indicates that in an equivalent magnetic field, the lognormally polydispersed ferrofluid is magnetically saturated faster than the corresponding monodispersion. Along the theoretical extrapolations, the polydispersity effects are evaluated for a typical ferrofluid of magnetite, with a dispersity of σ =0.20. The results indicate that the lognormal polydispersity leads to a slight increase of the saturation magnetization, but a noticeable increase of the speed to reach the saturation value in an equivalent magnetic field.

Abstract: Based on a lognormal particle size distribution, this paper makes a model analysis on the polydispersity effects on the magnetization behaviour of diluted ferrofluids. Using a modified Langevin relationship for the lognormal dispersion, it first performs reduced calculations without material parameters. From the results, it is extrapolated that for the ferrofluid of lognormal polydispersion, in comparison with the corresponding monodispersion, the saturation magnetization is enhanced higher by the particle size distribution. It also indicates that in an equivalent magnetic field, the lognormally polydispersed ferrofluid is magnetically saturated faster than the corresponding monodispersion. Along the theoretical extrapolations, the polydispersity effects are evaluated for a typical ferrofluid of magnetite, with a dispersity of $\sigma$ =0.20. The results indicate that the lognormal polydispersity leads to a slight increase of the saturation magnetization, but a noticeable increase of the speed to reach the saturation value in an equivalent magnetic field.

Key words: ferrofluid, polydispersity effects, lognormal distribution

中图分类号:  (General theory and models of magnetic ordering)

  • 75.10.-b
75.50.Mm (Magnetic liquids) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects)