In
this work, nanocrystalline MgFe2O4 powders were
synthesized by co-precipitation method and then
heat treated at different temperatures in the range
from 200 - 1400°C with the objective of obtaining
superparamagnetic properties. The single phase cubic
structure of MgFe2O4 with space
group Fd3m
was confirmed by powder X-ray diffraction (XRD), and
the average crystallite size of each sample has
been estimated from the (311) peak of the XRD spectra
using the Debye-Scherrer equation.
Formation of ferrites has also been studied by using
FTIR. On heating, the crystallite size increased
with corresponding increase in saturation magnetization
(Ms), and for
1400°C, it is 27.96 emu/g that is
close to the bulk MgFe2O4. On
increasing the crystallite size, the coercivity (Hc) increased passed
through a maximum and then dropped, indicates a
transition from single to multi-domain state at a
critical particle size ~52.5 nm. B-H loop measurements
have been carried out by B-H loop tracer. The
room temperature Mössbauer spectra of the samples show
six-figure patterns for higher crystallite
size and a doublet pattern for smaller crystallite
size, which is confirmed the appearance of
superparamagnetic (SPM) relaxation of the nanoparticles
with crystallite size up to 7.7 nm in the
samples. Curie temperatures have been determined from
the temperature dependence of
permeability. Curie temperatures for the samples of
this composition do not vary significantly with the
variation of sintering temperatures. From the Raman
spectrum all the peaks observed in samples
matched with Raman active modes of MgFe2O4 spinel
structure. The optimized properties make these
nanoparticles a potential candidate for various
applications including biomedical field.
Author
(s) Details
Dr. Engr. Sheikh Manjura Hoque,
Materials Science Division, Atomic Energy Centre, Dhaka – 1000,
Bangladesh.
Dr. Harinarayan Das,
Materials Science Division, Atomic Energy Centre, Dhaka – 1000,
Bangladesh.
Dr. Nipa Debnath
Departtment of Physics, Jagannath University, Dhaka – 1100,
Bangladesh.
Md. Tanvir Hasan
Departtment of Physics, Chittagong University, Bangladesh.
Prof. Dr. D. P. Paul,
Departtment of Physics, Chittagong University, Bangladesh.
Prof. Dr. S. S. Sikder
Departtment of Physics, Chittagong University, Bangladesh.
Prof. Dr. Kamanio Chattopadhayay
Department of Materials Engineering, Indian Institute of Science,
Bangalore, India.
View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/250
No comments:
Post a Comment