Magnetic birefringence of ferrofluids. I. Estimation of particle size

Abstract

The magnetic birefringence of various samples of Fe3O4 ferrofluids with particle sizes in the range of approximately 8.5-18.5 nm has been measured in field strengths of 5*10-4 to 5*10-1 T. For all the samples it has been found that in low fields the birefringence varies as the square of the field strength, indicating a classical behaviour of the particles. The size of the particles and the width of the particle size distribution curve have been estimated from an analysis of the variation of the birefringence with the applied magnetic field; the results obtained are in good agreement with results obtained from electron microscope and magnetic susceptibility measurements.

Magnetic birefringence of iron oxyhydroxide nanoparticles stabilised by sucrose

“…3) in contrast to the situation observed for magnetite particles in different liquid carriers [38] or covered with dextran [33]. As reported by Gutierrez et al [18], magnetisation of ironsucrose measured in fields up to 5 T and at a few temperatures did not reach the saturation level either.…”

“…The value obtained may be now compared with the results found for similar nanoscale systems. An estimation made using literature data [38] for magnetite particles with the core diameter of about 10 nm and in some other liquid carrier provide Da mag in the range 3.7-14.7 Â 10 À 37 Fm 2 . Our measurements of the anisotropy of the optical polarizability for aqueous suspension of magnetite particles coated with dextran having the core diameter of 15 nm, gives Da mag E7 Â 10 À 37 Fm 2 [33].…”

Versatile transmission ellipsometry to study linear ferrofluid magneto-optics

“…Both experimental and theoretical work is focused on elucidating the origin of the magneto-optical properties of these suspensions and exploring their applicability as active optical devices [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Initially, the theoretical description of the magneto-optical properties of ferrofluids was based on the alignment of slightly non-spherical particles with uniaxial magnetic anisotropy in an applied magnetic field [9].…”

“…The magneto-optical properties of ferrofluids have been investigated in the past with a number of different experimental set-ups [9,10,14,[17][18][19][20]22]. Most often only birefringence is considered, and the magnetically induced dichroism is neglected.…”

Birefringence of maghemite-based magnetic fluid in the highly concentrated regime

“…The traditional techniques used in the investigations are the high-resolution microscopy [5], X-ray diffraction [6], static magnetic birefringence [7], and magnetometry [8]. Since the last decade magnetic resonance has been systematically used as a valuable tool in the investigation of several properties of MFs [9].…”