Comparison between a magneto-optical method and Fannin´s technique for the measurement of Brown´s relaxation frequency of ferrofluids

Author

Payet, B. ; Siblini, A. ; Blanc-Mignon, M.F. ; Noyel, G.

Author_Institution

L.R.C.C.I., St.-Etienne Univ., France

Volume

35

Issue

3

fYear

1999

fDate

5/1/1999 12:00:00 AM

Firstpage

2018

Lastpage

2023

Abstract

A magneto-optical method, conceived in our laboratory to measure Brown´s relaxation frequency of ferrofluids, is compared with Fannin´s technique based on impedance measurements (slit toroid). We have developed a complete theory and an experimental setup of the first method and have briefly described the second one. We present a study of Brown´s relaxation of cobalt ferrite Fe₂CoO₄ in different carrier liquids (glycerol, diethylene glycol, dibutyl phthalate, and water). The two methods show very close results, proving the high sensitivity of both. The relation between the viscosity η and Brown´s relaxation frequency f_B has been verified. Moreover the analysis of relaxation and viscosity versus temperature has enabled us to estimate the hydrodynamic diameter of particles

Keywords

Brownian motion; cobalt compounds; ferrites; magnetic fluids; magnetic particles; magnetic permeability; magnetic relaxation; magnetic variables measurement; magneto-optical effects; particle size measurement; viscosity; Brown´s relaxation frequency; CoFe₂O₄; Fannin´s technique; Fe₂CoO₄; carrier liquids; ferrofluids; hydrodynamic diameter; impedance measurements; magneto-optical method; slit toroid; Cobalt; Ferrites; Frequency measurement; Impedance measurement; Iron; Laboratories; Liquids; Temperature sensors; Time of arrival estimation; Viscosity;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.764903

Filename

764903