Magnetic properties of Ni1.5Fe1.5O4 ferrite
nanoparticles prepared at highly alkaline medium
K.S.Aneeshkumar*, R.N.Bhowmik
Department of Physics, Pondicherry University, R. Venkataraman Nagar, Kalapet, Pondicherry-605014, India
*
Corresponding author’s e-mail: aneeshkumar20sd@gmail.com
Abstract
experiment
expt.-fit
(a)
(c)
profile fit
Bragg position
0.4
H=50 Oe
100
0.2
0.0
0
(d)
0.8
H=100 Oe
-100
20
30
40
50
2(deg)
60
70
6
Sample preparation
Nickel and iron nitrates were used as starting
solutions. NaOH solution was used to maintain pH at ~
12 during coprecipitation at 60°C for 4 hrs. A reddish
brown precipitate was formed and washed several times
to get the ferrite powder. The brownish black powder
was annealed at different temperatures until the cubic
spinel phase was confirmed at 800 °C. The prepared
sample was annealed up to 1000 °C for studying the
grain size effect and we present this sample.
Results and Discussions
XRD profile of the sample annealed at 1000 °C
matched to single phased cubic spinel structure of lattice
constant 8.2895Å (Fig. 1(a)). The peaks appeared broad
due to nano- crystalline structure with average grain size
 30 nm. The hysteresis loop (Fig. 1(b)) indicates soft
ferromagnetic properties with coercivity  82 Oe. The
magnetization is not saturated even at 70 kOe. The
spontaneous magnetization ( 6.7emu/g) was calculated
using Arrot plot (plot of M2 v/s H/M). The smaller value
of spontaneous magnetization in comparison to 55 emu/
g for NiFe2O4 ferrite is attributed to higher Ni content
and also superparamagnetic feature of the nanoparticles.
The squareness value of the sample is 0.10.
3
M(emu/g)
Ni doped Fe3O4 provides an excellent route to
tailor soft ferromagnetic properties in ferrites [1-3]. The
reports of Ni rich side of NixFe3-xO4 (0 ≤ x ≤ 2) series
are limited number in literature. With the objective of
developing room temperature soft ferromagnetic ferrite,
we have studied the magnetic properties of Ni1.5Fe1.5O4,
a specific composition of Ni doped Fe3O4 with Ni and
Fe ratio 1:1.
0.4
(b)
Introduction
(e)
H=500 Oe
0
3
-3
-6
-5000
4
2
1
0
Field (Oe)
5000
0
50
100 150 200
Temperature (K)
250
300
Fig. 1: (a) XRD profile, (b) M-H loop, and temperature
dependence of magnetization at different fields under
ZFC and FC modes (c-e). ZFC (black) and FC (red).
Superpramagnetic blocking of the ferromagnetic nanoparticles was confirmed from temperature dependence
of magnetization measurements (Fig. 1(c-e)).
Conclusions
Soft ferromagnetic properties have been tuned
in Ni1.5Fe1.5O4 ferrite by preparing the sample at highly
alkaline medium and annealing of as prepared powder at
different annealing temperatures.
Acknowledgment
We acknowledge CIF, Pondicherry University
for experimental facilities and UGC Consortium, Indore
for low temperature magnetic measurements. RNB
acknowledge the Research grant from UGC (No. 42804/2013 (SR), Govt. of India.
References
[1] S. Son, M. Taheri, E. Carpenter, V. G. Harris, and
M. E. McHenry, J. Appl. Phys. 91 (2002) 7589-7591
C.N. Chinnasamy et al., Phys. Rev. B. 63, (2001)
184108.
[3] J. Jacob and M.A. Khadar J. Appl. Phys. 107,
114310 (1-20)
M(emu/g)
Keywords: Nickel ferrite, Coprecipitation, Ferromagnetism,
Superparamagnetism.
200
Intensity(c/s)
The nanoparticles of Ni1.5Fe1.5O4 ferrite have been
prepared by coprecipitation of iron and nickel nitrates solution
in high alkaline medium. The ferromagnetic loop of the
sample is not saturated even at 70 kOe due to coexistence of
superparamagnetic component. The superparamagnetic feature
is confirmed from temperature dependence of magnetization
measurements.