Anantharaman, M R; Swapna, Nair S; Francis, Xavier; Joy, P A; Kulkarni, S D(Elsevier, September 20, 2007)
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Abstract:
Ferrofluids belonging to the series NixFe1 xFe2O4 were synthesised by two different procedures—one by standard co-precipitation
techniques, the other by co-precipitation for synthesis of particles and dispersion aided by high-energy ball milling with a view to
understand the effect of strain and size anisotropy on the magneto-optical properties of ferrofluids. The birefringence measurements were
carried out using a standard ellipsometer. The birefringence signal obtained for chemically synthesised samples was satisfactorily fitted to
the standard second Langevin function. The ball-milled ferrofluids showed a deviation and their birefringence was enhanced by an order.
This large enhancement in the birefringence value cannot be attributed to the increase in grain size of the samples, considering that the
grain sizes of sample synthesised by both modes are comparable; instead, it can be attributed to the lattice strain-induced shape
anisotropy(oblation) arising from the high-energy ball-milling process. Thus magnetic-optical (MO) signals can be tuned by ball-milling
process, which can find potential applications
Description:
Journal of Magnetism and Magnetic Materials 320 (2008) 815–820
Swapna, Nair S; Francis, Wavier; Joy, P A; Kulkarni, S D; Anantharaman, M R(Elsevier, March , 2008)
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Abstract:
Ferrofluids belonging to the series NixFe1 xFe2O4 were synthesised by two different procedures—one by standard co-precipitation
techniques, the other by co-precipitation for synthesis of particles and dispersion aided by high-energy ball milling with a view to
understand the effect of strain and size anisotropy on the magneto-optical properties of ferrofluids. The birefringence measurements were
carried out using a standard ellipsometer. The birefringence signal obtained for chemically synthesised samples was satisfactorily fitted to
the standard second Langevin function. The ball-milled ferrofluids showed a deviation and their birefringence was enhanced by an order.
This large enhancement in the birefringence value cannot be attributed to the increase in grain size of the samples, considering that the
grain sizes of sample synthesised by both modes are comparable; instead, it can be attributed to the lattice strain-induced shape
anisotropy(oblation) arising from the high-energy ball-milling process. Thus magnetic-optical (MO) signals can be tuned by ball-milling
process, which can find potential applications.
Anantharaman, M R; Nampoori, V P N; Abraham, V S; Rajesh, S; Swapna, Nair S(Elsevier, December 27, 2005)
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Abstract:
Fine magnetic particles (sizeffi100A ˚ ) belonging to the series ZnxFe1 xFe2O4 were synthesized by cold co-precipitation methods and
their structural properties were evaluated using X-ray diffraction. Magnetization studies have been carried out using vibrating sample
magnetometry (VSM) showing near-zero loss loop characteristics. Ferrofluids were then prepared employing these fine magnetic powders
using oleic acid as surfactant and kerosene as carrier liquid by modifying the usually reported synthesis technique in order to induce
anisotropy and enhance the magneto-optical signals. Liquid thin films of these fluids were prepared and field-induced laser transmission
through these films was studied. The transmitted light intensity decreases at the centre with applied magnetic field in a linear fashion
when subjected to low magnetic fields and saturate at higher fields. This is in accordance with the saturation in cluster formation. The
pattern exhibited by these films in the presence of different magnetic fields was observed with the help of a CCD camera and was
recorded photographically
Description:
Journal of Magnetism and Magnetic Materials 305 (2006) 28–34