Glacier Journal of Scientific Research ISSN:2349-8498
The Structural and Magnetic Properties of Ni-Ferrite
Nano-particles at Annealing Temperature
Chaturbhuj Ojha and A.K.Shrivastava#
MPCT College, walior
School of Studies in Physics, Jiwaji University, Gwalior
Email: cbophy@gmail.com
#
Abstract. Magnetic nanoparticles NiFe2O4 were prepared by chemical co-precipitation technique using the
chlorides of Ni, Fe (III) and oleic acid. The precursors were annealed at different temperature 500, 700, and 900 °C.
The XRD of samples show the presence of inverse cubic spinel structure. Grain size was determined using Scherrer
formula and SEM technique. The Particle size, Lattice parameter and X-ray density were also estimated from X-ray
diffraction data. The particles size was found to vary from 17nm to 37 nm and largely depends on the annealing
temperature. Magnetization measurements have also carried out using VSM and it was found that saturation
magnetization (Ms), Remanance (Mr) and coercivity (Hc) of nano ferrite materials are lower compared to bulk
materials.
Keywords: Ferrite, Nanoparticles, XRD, SEM, VSM.
PACS: 68.55.J-, 81.05.Dz, 81.10.Dn, 81.15.Rs
INTRODUCTION
Development of nano particles of various materials is a
challenge to Scientists. The technological significance
of nano materials, compelled to innovate new methods
for their synthesis in laboratories. The magnetic
properties of these materials are strongly dependent on
grain size, size distribution and morphology of
crystallites. Ferrites are more suited at high
frequencies than other soft magnetic materials. They
show high electrical resistivity in addition to their
ferrimagnetic behavior [1]. Materials in nanosize have
wide application in designing a large variety of
integrated circuit, reading – writing heads, sensor,
catalysts and magnetic recording media. Present
investigation aims to carry out the study of structural
and magnetic properties of the NiFe2O4 (annealing
Temperature 500, 700 and 900°C) synthesized using
the co-precipitation method.
EXPERIMENTAL PROCEDURE
NiFe2O4 ferrite was synthesized using chlorides of Ni
and Fe (III). The solution was constantly stirred using
stirrer and the pH of solution was kept at 10. The
mixture was slowly heated to 85 °C. Thereafter, a
specified amount of oleic acid (5 ml) was added to the
solution as the surfactant which acts as coating
material. The resulting fluid was centrifuged at 12000
rpm for 10 minutes. The material collected at the
bottom was repeatedly washed with acetone for getting
dry particles. Acquired substance was then further
dried by keeping oven. The final product thus obtained
was brown in colour. The co-precipitated ferrite
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agglomerates were than ground to get fine material
particles. The powdered material was subsequently
heat treated in a box furnace at 500, 700 and 900 ºC.
The material so obtained was subjected for structural
characterization
using
XRD
and
Magnetic
characterization using VSM.
RESULT AND DISCUSSION
XRD patterns of all the samples annealed at different
temperature 500, 700 and 900 °C are shown in Fig. 1.
The diffractograms shows different reflection planes
indexed as (220), (311), (222), (400), (422), (511),
(440) and (620), which indicates the presence of
inverse spinal cubic structure of NiFe2O4. The X-ray
patterns of NiFe2O4 have been analyzed and compared
with that reported in literature [2, 3, and 4]. Diffraction
peaks corresponding to any other phase or impurities,
such as α-Fe2O4 or NiO, were not observed. Thus the
method adopted to obtain nano particles provides
impurity free NiFe2O4. Furthermore, it is clear from
the XRD pattern that the diffraction peaks becomes
sharper and narrower with increasing annealing
temperature. This shows an enhancement in the
crystallinity in the material. The XRD pattern show
that the sample are crystalline having strong
orientation along (311) plane with 2Ө = 35.6°.
Average particle sizes as calculated using the Scherrer
equation was found to vary from 17nm to 37nm after
annealing the samples at 500, 700, and 900 ºC,
respectively. The lattice parameter and X-ray densities
as calculated for these samples are listed in table1.
SEM micrographs are shown in Fig. 2. SEM figures
show uniform, almost spherical structural morphology
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Glacier Journal of Scientific Research ISSN:2349-8498
with a narrow size distribution of particles. Good
agreement in XRD and SEM data are observed.
FIG. 2. SEM images of NiFe2O4.
45
Magnetic Moment (emu/gm)
The plots of magnetization versus applied magnetic
field corresponding to different grain size of the
samples are shown in Fig. 3. The material show
ferromagnetic hysteresis only up to the magnetic field
2000 gauss. Beyond this the magnetization increases
with increasing field and finally saturates. The field
required for saturation for all the specimens does not
differ much; instead the difference is well within (±10
gauss). Saturation magnetization (Ms), Remanance
(Mr) and Coercivity (Hc) were evaluated using these
plots. These values along with annealing temperature
are shown table 1. In case of nano materials the
magnetic properties depends on shape and size of the
nano particles [5, 6]. The variation in coercivity (Hc),
with particle size can be explained on the basis of
domain structure, critical diameter and anisotropy of
the crystal [7]. In fact a crystallite spontaneously
breaks up in to a number of domains in order to reduce
the large magnetization energy which it would have if
it were a single domain [8].
25
5
-10000 -8000
17
21
0.8304
0.8315
5.4372
5.4160
1.2
2.4
160
148
19
33
900
37
0.8338
5.3715
6.16
112
42
-2000
-5
0
2000
4000
6000
8000
10000
-35
-45
Magnetic field (gauss)
FIG. 3. Magnetization Vs Magnetic field
REFERENCES
1.
2.
4.
5.
6.
7.
8.
R D K Mishra et al.,.
Material Science and technology 19 (2003) 1617
Manish Srivastava, and Animesh ku. Ojha;
J. of Alloys and Compounds 481 (2009) 515
Youjin Lee, Jinwoo Lee, and Taeghwan Hyeon;
Adv. Funct. Mater. 15 (2005) 503
Santi Maensiri, Chivalrat Masingboon, & Supapan
Seraphin ;
Scripta Materialia 56 (2007) 797
J. M. D. Coey ;
Phys. Rev. Lett. 27 (1971) 1140
K. Maaz, and Abdullah Ceylan ; J.of Magnetism
& Magnetic Materials 308 (2007) 289
B. D. Cullity ; Introduction to Magnetic Materials,
Adddison – Wesley publishing Co. Inc. Reading
MA (1972)
M. Georgea and M. R. Anantharaman ;
J. Magn. Magn. Mater. 302 (2006) 190
(311)
Thus using Co-precipitation method, nanoparticles of
NiFe2O4 can easily be synthesized. The particle size
can be changed by annealing the material. The
technique also provides good stoichiometric control.
The XRD and SEM data on particle size show good
agreement with each other. XRD analysis confirms
that the sample posses inverse spinel cubic structure.
The magnetic parameters show particle size dependent
behavior. Coercivity shows a monotonic behavior with
particle size, i.e., for small particle size, the coercivity
is higher and it decreases for large size particles.
-4000
-25
3.
CONCLUSION
-6000
-15
(Ms)
emu/g
500
700
700 °C
500 °C
15
TABLE 1. Showing the variation different parameters
Lattice
Annealing Particle
X-ray density (Mr)
(Hc)
Parameter
Temp ºC size, nm
( gm/ cm3) emu/gm gauss
a (nm)
900 °C
35
1200
(440)
(620)
600
(422)
(511)
(400)
800
(222)
(220)
Intensity (a.u.)
1000
900 ºC
400
700 ºC
500 ºC
200
0
15
25
35
45
55
65
75
85
2 θ (Degree)
FIG. 1. X-ray diffraction of NiFe2O4
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