Frequency dependence of dielectric anisotropy in ferrofluids

被引：21

作者：

Spanoudaki, A

Pelster, R

机构：

[1] Univ Cologne, Inst Phys 2, D-50937 Cologne, Germany

[2] Univ Cologne, Inst Phys & Ihre Didaktik, D-50931 Cologne, Germany

来源：

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS | 2002年 / 252卷 / 1-3期

关键词：

ferrofluids; dielectric spectroscopy; magnetodielectric anisotropy; hopping; relaxation; frequency dependence;

D O I：

10.1016/S0304-8853(02)00718-7

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We have conducted broadband, temperature-dependent dielectric spectroscopy on ferrofluids of various concentrations. We study the change of the permittivity on application of a homogeneous magnetic field (approximate to0.5 T, parallel or orthogonal). The results reveal that the field-induced magnetodielectric effect is markedly frequency dependent and should be attributed to two different mechanisms: The structural anisotropy affects not only the interfacial polarisation of the nanoparticles, but also the strength of the hopping process observed in the samples. Both these effects influence the low-frequency permittivity values. High-frequency measurements should be used to derive information on the microstructure by means of effective media analysis. (C) 2002 Elsevier Science B.V. All rights reserved.

引用

页码：71 / 73

页数：3

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