Authors: Sk. Manjura Hoque
Affilation: Atomic Energy Centre, Bangladesh Atomic Enegry Commission, Bangladesh
Pages: 518 - 521
Keywords: ferrite nanoparticle, chemical co-precipitation, permeability, transport properties, Curie temperature
NiFe2O4 nanoparticle has been prepared by chemical co-precipitation technique. X-ray diffraction patterns of as dried and samples calcined at different temperatures for four hours have been studied. The sample in the as dried condition is fully single phase and no extra peak could be observed in XRD patterns. The grain size has been obtained from Scherrer’s formula and found as 7 nm. When the samples were calcined at higher temperatures subsequent grain growth led the grain size to 16 nm at 600°C and increases further. Frequency dependence of real part of initial permeability has been measured for the samples calcined different temperatures. Permeability increases with grain growth as expected i.e. when the grain size is larger the permeability is higher. The presence of small grain size interferes with wall motion, which decreases permeability and increases the stability region of permeability. Microstructure studies have been performed by Scanning Electron Microscope. Magnetic phase transition temperature has been obtained from temperature dependence of initial permeability for the samples calcined at different temperatures. The behavior of grain size dependence of Curie temperature has been explained by finite size scaling theory. Field dependence of magnetization of as-dried sample shows superparamagnetic behavior, which has been attracted by the researcher for its enormous potential for biomedical application. Transport properties of the samples calcined at higher temperatures have also been described.
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