著者

稲葉 信幸 宮島 英紀 武富 荒 近角 聡信

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.13, no.2, pp.245-248, 1989-04-30 (Released:2007-12-07)

参考文献数

4

被引用文献数

2 2

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Magnetization (M), field induced magnetic anisotropy (Ku), rotational hysteresis loss (Erot) and melting point (Tm)f water- and paraffin-base ferrofluids were investigated in a temperature range from 77 K to 300 K as a function of the density of colloidal particles. Both paraffin and paraffin-base fluids were melted down at the temperature range from 180 to 210 K. In this range, the values of M and Erot, for paraffin-base fluids increased and Ku decreased with increasing temperature. These properties are interpreted by assuming that liquid-state and solid-state parts in paraffin exist in this tempetarure range and that the volume of solid-state part decreases with increasing temperature. The freezing point depression was observed in water-base fluids.

著者

稲葉 信幸 宮島 英紀 武富 荒 近角 聡信

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.12, no.2, pp.283-286, 1988-04-30 (Released:2007-12-07)

参考文献数

6

被引用文献数

5 3

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The magnetization process of a ferrofluid whose carrier fluid is paraffin was investigated in a temperature range from 77K to 300K as a function of the intensity of cooling field and the freezing rate. Phase transition between liquid state and solid state can be simulated by using the ferrofluids as a magnetic probe. The uniaxial magnetic anisotropy was induced by field cooling in frozen ferrofluids. This induced anisotropy decreased with increasing temperature near the melting point and disappeared at 30K higher temperature than the melting point. In this region the rotational hysteresis was observed. The anisotropy constant K near the melting point was described by the equation K=A·exp(ΔEK/kT). The value of the activation energy ΔEK was almost the same as that of ΔEη estimated from the viscosity vs. temperature relation η∝ exp(ΔEη/kT).

著者

武富 荒 小川 伸一 宮島 英紀 近角 聡信

出版者

公益社団法人 日本磁気学会

雑誌

日本応用磁気学会誌 (ISSN:02850192)

巻号頁・発行日

vol.12, no.2, pp.263-268, 1988-04-30 (Released:2007-12-07)

参考文献数

20

被引用文献数

14 16

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Magnetooptical effect of magnetic fluids is investigated. The phase difference θ between the ordinary ray and the extraordinary ray which are transmitted through the magnetic fluid thin film was found to be described in the functional form θ1f(H)/[T-T1+f(H)], where H is the magnetic field applied to the magnetic fluid thin film, T is the absolute temperature of the film, f(H) is a certain increasing function of H and T1, θ1 are the positive constants. The field dependence of light transmissivity of magnetic fluid thin films is well described by the cluster model of ferrous colloidal particles in the applied field direction when the aggregation is small. The field dependence of transmissivity is, however, interpreted neither by the electric absorption of the clusters nor by the Rayleigh scattering when the cluster becomes larger. The diffraction effect by the linear clusters directed to the applied field must be taken into account in interpreting the light extinction.