Content uploaded by Rakesh Kr Singh
Author content
All content in this area was uploaded by Rakesh Kr Singh on Jan 20, 2021
Content may be subject to copyright.
Content uploaded by Rakesh Kr Singh
Author content
All content in this area was uploaded by Rakesh Kr Singh on Oct 14, 2016
Content may be subject to copyright.
9
Manthan, International Journal, Vol. 12, June, 2011, Pages 9-11
ISSN No. 0974-6331 www.bbmanthan.info
Rakesh Kumar Singh a, A. Narayan b, A. Yadav c, S.Layek d, H. C. Verma d
aDepartment of Physics, Patna Women’s College, Patna University, Patna, Bihar, India
bDepartment of Physics, Patna University, Patna, Bihar, India
cVidyavihar Institute of Technology, Purnea, Bihar, India
d Department of Physics, IIT Kanpur, Kanpur, India
Abstract
Nanocrystalline Nickel Zinc Ferrite particles (NixZn1-
xFe2O4) with different composition were prepared by
Citrate precursor method. The ferrite powders were
characterized using X-ray diffraction (XRD), Vibrating
sample magnetometer (VSM) and Mossbauer
Spectroscopy tools. The maximum value of saturation
magnetization was observed as 52.18 emu/g and
Coercivity as 116.10 Oe in sample with x = 0.8. The
Mössbauer spectroscopy results show two
environments for iron nuclei. In contrast to bulk Ni-Zn
ferrites, the lattice parameter in our samples has a
tendency to nonlinearly decrease with increase in the
proportion of Nickel. The range of average particle
size is 7 nm to 18 nm as obtained from XRD line
broadening.
Keywords: Ferrite, Nanoparticle, Magnetic Properties,
Mossbauer studies
Introduction
Nanocrystalline Spinel Nickel zinc ferrites have
been investigated extensively in recent years because
of their potential applications in various electronics
devices, radio frequency circuits, high quality filters,
rod antennas, transformers, read-write heads for high
speed digital tape recorders and magnetic storage
devices1,2,3. Their multifarious use in electronics
industry stems from the fact that they have large
permeability even at high frequency4. Moreover, they
have remarkably high electrical resistivity, mechanical
hardness, chemical stability and reasonable cost.
Several researchers have used citrate precursor method
for synthesis of ferrites in bulk as well as nano sizes
due to its attractive features like low cost and ease of
preparation5-11. We have also used the same method for
preparing our samples.
Materials and methods
Synthesis of Ni-Zn Ferrite Nanoparticles: Samples
of nanometer-sized nickel-zinc ferrite powder, NixZn1-
xFe2O4(x=0.2, 0.4, 0.5, 0.6, 0.8) were prepared by
using the Citrate precursor method. Ferric nitrate,
nickel nitrate and Zinc nitrate were taken in
stoichiometric proportions as starting materials.
Aqueous solutions of these salts were prepared
separately by dissolving the salt in minimum amount
of deionized water while stirring constantly. The
solutions were then mixed together. Aqueous solution
of citric acid was prepared in adequate quantity by
weight and was added to the prepared salt solutions.
The mixture was heated at temperature about 60oC to
80oC for two hours with continuous stirring. This
solution was allowed to cool to room temperature and
finally it was dried at 90-95oC in an oven until it
formed a brown color fluffy mass. This precursor was
heated at 450oC for one hour in a muffle furnace. By
this process, the precursor decomposed to give nickel-
zinc ferrite powder consisting of nanometer size
particles.
Results and Discussions
Structural features: The ferrite samples prepared
as described above were structurally characterized
using large angle X-Ray Diffractometer (XRD). In all
our samples of Ni-Zn mixed ferrites, XRD patterns
show diffraction peaks that correspond to spinel
ferrites mainly, together with small peaks of Hematite
(Figure 1) and sodium Zincate tetrahydrate. However,
the intensities corresponding to these impurity phases
are small. Similar peaks were also observed in Ni-Zn
ferrite samples prepared using hydrothermal technique4.
Albuquerque et al. (2000) have prepared ferrite
samples by coprecipitation technique with heat
treatment at 300oC as well as higher temperatures12 and
it was shown that samples exhibit good structural
ordering only for heat treatment at temperature higher
than 400oC. The other phases (in addition to spinel)
may be attributed to inaccuracy in stoichiometric
proportions, inhomogeneity at microscopic scale and
presence of unreacted chemicals in the finished
product.
The lattice constant was observed to change with
the proportion of nickel. Apart from the anomalous
result for x= 0.2, as the proportion of nickel is
increased from x= 0 to 0.8, the lattice constant shows a
Structural, Magnetic and Mössbauer Studies of Nanocrystalline Ni-Zn Ferrite,
Synthesized using Citrate Precursor Method
10
Manthan, International Journal, Vol. 12, June, 2011, Pages 9-11
ISSN No. 0974-6331 www.bbmanthan.info
decreasing trend. A similar trend has also been
reported for bulk nickel-zinc ferrite materials earlier 13.
Fig.1: XRD pattern for Ni0.8Zn0.2Fe2O4 Nanomaterials
Lattice const as a function of Nickel Zinc ratio
8.28E-10
8.3E-10
8.32E-10
8.34E-10
8.36E-10
8.38E-10
8.4E-10
0 20406080100
Nickel %
Lattice cons tant
Fig. 2: Variation of Lattice constant with percentage
increase of Nickel
Magnetic and Mossbauer studies: The ferrite
samples were magnetically characterized using VSM
as well as by Mössbauer spectroscopy. The magnetic
parameters obtained from VSM measurements of the
six samples of Ni-Zn mixed ferrite particles are
tabulated in Table 1. The magnetic hysteresis curves
for Ni0.8Zn0.2Fe2O4 nanoparticles are shown in figure 3.
Fig. 3: Hysteresis Loop for Ni 0.8Zn 0.2Fe2O4
Nanoparticles
The values of the magnetization parameters do not
show a systematic trend with change in composition.
Partly the impurity phases and partly the varying
particle size might be responsible for this. The
annealing temperature of 4500 C may not be optimum
for all the samples. The most interesting case seems to
be with Ni0.8Zn0.2Fe2O4 ,where both the coercive field
(116.10 Oe) and the saturation magnetization (52.18
emu/g) are largest. Values of saturation magnetization
higher than 50 emu/g have so far been achieved by
using other methods14,15, only through sintering at
temperatures much above 450oC, the sintering
temperature used in the present method. Synthesing
ferrite samples at lower temperatures have its own
advantages as the grain growth is checked and one is
more likely to get strain-free nanoparticles.
Table 1: Magnetic parameters of the Nickel Zinc
Ferrite samples
Sample Hc (Oe) Mr (emu/g) Ms
(emu/g) Squareness/
Particle size
(nm)
Ni0.2Zn 0.8Fe2O4. 22.42 0.5744 17.50 0.033/ 16
Ni0.4 Zn.6Fe2O4 1.53 0.1049 43.43 0.002/7
Ni0.5Zn.0.5Fe2O4 90.86 5.658 40.54 0.140/16
Ni 0.6 Zn0.4Fe2O4 35.77 2.678 43.64 0.059/9
Ni 0.75 Zn 0.25 Fe2O4 93.10 4.610 38.94 0.118/9
Ni 0.8Zn 0.2Fe2O4 116.10 11.38 52.18 0.148/18
Caizer and Stefaneseu15 have reported that the
magnetic properties are determined by the size of the
nanocrystallites. The decrease in saturation
magnetisation with decrease in particle size of the
nanocrystallites can be attributed to surface effect, spin
canting and broken exchange bonds16. In our studies,
we have also obtained lowering of saturation
magnetization as compared to bulk values.
-15 -10 -5 0 5 10 15
98.0
98.5
99.0
99.5
100.0 Ni
0.8Zn0.2Fe2O4 (RT )
Transmission(%)
Ve locity(m m /s)
Fig. 4: Mössbauer Spectrum for Ni 0.8Zn 0.2Fe2O4
Nanomaterials
The Mössbauer pattern of the Ni0.8Zn0.2Fe2O4
sample (Fig. 4) shows that two sextets are superposed,
one over the other. Ni-ferrite is an inverse ferrite and
one expects Fe ions to occupy both A and B sites. Zn
has a preference for A-sites and hence the area
corresponding to the A-site sextet should be somewhat
smaller to that corresponding to B-site. The well
resolved six-line pattern shows that there are no
significant superparamagnetic fluctuations of the
magnetic moment. However, the Bhf values of the
sextets in the spectrum (47.6 T and 43.5 T) are less
than the values expected for bulk samples (50 T to 55
T) indicating the fact that the particles are in nanosize
but the blocking temperature is above room
temperature. The XRD peak broadening for this
particular sample gives the average particle size to be
18 nm consistent with the reduced Bhf.
Conclusion
We used a single annealing temperature for all our
samples of nanocrystalline Ni-Zn mixed ferrite. We
observed that the magnetic properties as well as
particle size depended on stoichiometric proportion of
11
Manthan, International Journal, Vol. 12, June, 2011, Pages 9-11
ISSN No. 0974-6331 www.bbmanthan.info
Nickel and Zinc. The maximum saturation
magnetization was found to 52.18 emu/g. This might
be a feature of the citrate precursor method that was
used by us. The lattice parameter has a tendency to
decrease with increase in the proportion of Nickel but
we did not get a straight line function as has been
reported for the case of bulk ferrites. The Mössbauer
spectrum shows that Fe occupies both the A and B
sites in the sample and superparamegnetic fluctuations
are not significant.
Acknowledgement
Authors, Rakesh K. Singh and A. Yadav are
thankful to Nalanda Open University, Patna for partial
financial support for this work.
References
[1] Sugimoto, M., J.Am. Ceram. Soc. 82 (1999) 269.
[2] Ishino, K. and Y. Naruniya, Ceram. Bull. 66, (1987)
1469.
[3] Gilot, B., Euro, Phys. J. Appl. Phys. 91 (2002) 10.
[4] Upadhaya, C., D. Mishra, H. C. Verma, S. Anand,
R.P. Das, J. Magn. Mag. Mat. 260 (2003) 188.
[5] Guaita, F. J., H. Beltron, E Cordoncillo, J. B.Carda,
P.Secribano, J. Euro. Ceram. Soc. 19 (1999) 363.
[6] Vijayalakshmi, A. and N.S. Gajbhiye, J. Appl. Phys.
83 (1998) 400.
[7] Kamble R.C. et al., J. Alloy. Comp., 491 (2010)
372.
[8] Costa, A.C.F.M, Tortella, E, M. R. Morelli,
R.H.G.A. Kiminami, J. Magn.Mag. Mat., 256
(2003) 174.
[9] Prasad, S., and N. S. Gajbhiye, J. Alloy. Comp.,
265 (1998) 27.
[10] Verma, A., T. C. Goel, R. G. Mendiratta, P.
Kishan. J. Magn.Mat., 192 (1999) 271.
[11] Narayan A, R. K. Singh, M. Roy, B. Pandey, V.
Kumar, H. C. Verma, Patna Univ. Jour. 31 (2007)
11.
[12] Albuquerque, A. S., Jose, D. Ardisson, Waldemar,
A.A. Maedo, J. Appl. Phys. 87 (2000) 4352.
[13] Smit, J. and H.P.J. Wijn, Ferrites, (1959) Philips
Technical Library, U. K. Edition, London. 145.
[14] Verma, A., T. C. Goel, R. G. Mendiratta, P.
Kishan., J. Magn. Mag.Mat. 208 (2000) 3119.
[15] Caizer, C. and M. Stefanescu, J. Phys. D: Appl.
Phys, 35 (2002) 3035.
[16] Coey, J . M. D., Phys. Rev. Lett. 27 (1971) 1140.
Corresponding Author:
Email: rakeshpu@yahoo.co.in
