Enhanced shape anisotropy and magneto-optical birefringence by high energy ball milling in NixFe1−xFe2O4 ferrofluids

Abstract

Ferrofluids belonging to the series Ni x Fe 1Àx Fe 2 O 4 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. r

Effects of γ-irradiation on AC electrical and impedance spectroscopy of Ni-Zn nano ferrites

“…Ni-Zi ferrites are also stable magnetic materials for making composites with various resins which is useful for moulding [8]. In the literature, ferrites are synthesized using high-energy ball milling [9], the low-cost sol-gel method [10], micro emulsion process [11], hydrothermal technique [12] and citrate precursor auto combustion method [13]. Among these, the solution processing of nano-crystalline Ni-Zn ferrites has attracted considerable interest due to the tailoring of their physical properties, recently identified with the highest magnetization value i.e.…”