Synthesis and Characterization of Bismuth Ferrite Nanoparticles
Anoopshi Johari
Department of Physics, National Institute of Technology, Kurukshetra 136119 Haryana
anoopshi.akg@gmail.com
OF ADAPTIVE VOLTERRA FILTERS
__________________________________________________________________________________________________________
.Abstract--In the present work, Nanoparticles (NPs) of
multiferroic bismuth ferrite (BiFeO3) were synthesized via a wet
chemical route using bismuth nitrate and iron nitrate as starting
materials and excess citric acid as chelating agent, respectively,
followed by thermal treatment at 350∘C, 450∘C and 550∘C. It was
found that BiFeO3 nanoparticles crystallized at 350∘C when
using citric acid as chelating agent. BiFeO3 nanoparticles with
different sizes distributions show obvious ferromagnetic
properties, and the magnetization is increased with reducing the
particle size.
The prepared samples were characterized by X-ray diffraction of
powder (XRD), scanning electron microscope (SEM) for
extracting their surface morphology and their crystallographic
structure. The surface morphology studies confirm the growth of
bismuth ferrite nanoparticles with their diameters in the range of
200nm to 500nm. The XRD analysis concludes the
rhombocentered structure of synthesized nanoparticles.
Keywords: Bismuth ferrite, Nanoparticles, X-ray diffraction
I. INTRODUCTION
BISMUTH Ferrite (BiFeO3, BFO) is one of the very few
multiferroic materials with a simultaneous coexistence of
ferroelectric with high Curie temperature (TC = 810-830˚C)
and anti-ferromagnetic order (below TN= 370˚C) parameters
in perovskite structure. However, these two ordering
parameters are mutually exclusive in principle because
ferroelectricity and magnetism require different filling states
of d shells of transition metal ions. Empty d shells mainly
exist in ferro-electricity, while partially filled d shells are
required in magnetism. Therefore multiferroic are rare and it
exhibits weak magnetism at room temperature.
Though BFO was discovered in 1960, recently there is a
renewed interest because of its possible novel applications in
the field of radio, television, microwave and satellite
communications, audio-video and digital recording and, as
permanent magnets. So far,
bismuth ferrite powders have been prepared by the solid-state
methods (classic [1, 2] and mechano-chemical ones [3] and
solution chemistry methods (such as precipitation/co
precipitation [4], sol–gel [5, 6] hydrothermal [7] and
sonochemical [8] ones). Most of the mentioned procedures
need high temperature treatments (>800°C). Due to the
requirement of nanosized oxides and in order to avoid bismuth
volatilization the developing of low temperature synthesis
methods is essential [9]. Previous studies have demonstrated
that synthesis of Bismuth Ferrites nanoparticles through a
traditional solid-state method produces poor reproducibility
and causes formation of coarser powders as well as
Bi2O3/Bi2Fe4O9 impurity phase [7], [8]. Up to date, several
chemical routes (for example: hydrothermal treatment,
mechano-chemical
synthesis
method,
and
sol-gel
methodology, etc.) have been successfully employed for
fabricating BFO nanoparticles. However, these approaches
have certain shortcomings such as impurities in the final
products [9].
In the present work, Bismuth ferrite (BiFeO3) nanoparticles
are successfully synthesized using citric acid. The sythesized
bismuth ferrite (BiFeO3) nano-particles were characterized by
X-Ray Differaction (XRD) and Scanning Electron Microscope
(SEM) for extracting their surface morphology and crystal
structure.
II. EXPERIMENTAL PROCEDURE
In the present work, sol-gel method is used. For the synthesis
of bismuth ferrite nano-particles, bismuth nitrate
[Bi(NO3)3·5H2O] and iron nitrate [Fe(NO3)3.9H2O] were
weighed and dissolved in de-ionized water to make a solution
of 0.2M. Afterwards some amount of diluted nitric acid (65%
to 68% HNO3) was added to the mixture. Then citric acid
(C6H8O7) was added to the solutions, this act as chelating
agent.
The light-yellow-colored solution was heated under vigorous
stirring. The beaker with solid deposit was kept in the oven at
150˚C. Powders were quarterly divided and calcinated in the
oven at 350˚C, 450˚C, and 550˚C respectively, to obtain well
crystallized Bismuth Ferrites nano-particles with controllable
sizes [10].
After the complete chemical synthesis and heat treatment of
the synthesized products, the sample were characterized using
X-ray diffraction (XRD) with a X-ray diffractometer with Cu
Kα radiation (λ = 0.154178 nm) and Scanning Electron
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Microscope (SEM) for extracting their surface morphology
and their crystallographic structure.
Formation of precursor
Figure 2: Bismuth Ferrites nanoparticles calcinated at different
temperature.
Bismuth nitrate
Solution
20mL diluted
Nitric acid
Iron nitrate
Solution
Mixed solution
Citric acid
91
Heating under vigorous stirring at 70˚
C
Fig. 1 Schematic for chelating complex formed by Citric acid, where
purple stands for Bi, blue for Fe, red for Oxygen and gray for Carbon
atoms.
Heating in the oven at 150˚C for 2 Hr
Brown powder is obtained
Calcined at 350˚C, 450˚C and 550˚C (
calcination time = 2Hr)
BiFeO3
Fig. 3 Process flow for the synthesis of Bismuth Ferrite
Nanoparticles.
III.
RESULTS AND DISCUSSION
The synthesized bismuth ferrite nanoparticles were
characterized by using the room temperature powder X-ray
18
diffraction with filtered 0.154 nm Cu Kα radiation for their
phase analysis studies at different calcined temperatures of
350˚C, 450˚C and 550˚C. The calcined samples are scanned in
a continuous mode from 20° – 80° with a scanning rate of
30/minute. The XRD analysis of BiFeO3 (BFO) powder
calcined at 350˚C,450˚C and 550˚C are shown in the Fig. 3.
The prominent peaks in xrd plot are indexed to various hkl
planes of BFO, indicating formation of BFO. Besides these
prominent peaks, some other peaks of low intensity are also
observed, which do not belong to BFO. The sample calcined
at 550˚C is having many extra peaks other than BFO whereas
that prepared at 350˚C is less impurity peaks. The literature
survey of BFO synthesis relates these impurity peaks to be
that of Bi2.88Fe5O12.
(300)
(208)
(220)
(036)
(312)
(125)
(211)
(122)
(113)
(012)
(202)
(0
12
)
)
(024)
(110)
The appearance of these extra phases at 550˚C could be due
to large bismuth loss at higher temperature. Powder calcined
at 450˚C is having less impurity phase of Bi2.88Fe5O12, as is
evident from the lesser peak height than 550˚C.The
synthesized bismuth ferrite nanoparticles were characterized
by using the SEM for revealing their surface morphology at
different calcined temperatures of 350˚C, 450˚C and 550˚C.
The particle size estimated from SEM images for the BFO
sample is about 200nm for the calcined temperature 350˚C,
400nm for the calcined temperature of 450˚C and 500nm for
the calcined temperature of 550˚C. The proportional increase
in particle size is also confirmed by their surface morphology
studies.
(b)
(c)
Mag : 5K
Mag : 10K
Fig. 4: SEM image of BiFeO3 nanoparticles synthesized at calcination
temperature of (a) 350˚C (b) 450˚C (c) 550˚C
IV. CONCLUSION
In the reported experiment, bismuth ferrite (BiFeO3)
nanoparticles are successfully synthesized by chemical route
method using citric acid. The sythesized bismuth ferrite
(BiFeO3) nanoparticles were characterized by X-Ray
Differaction (XRD) and Scanning Electron Microscope
(SEM). The XRD characterization results indicates the
rhombo centered structure of bismuth ferrite nanoparticles and
the SEM anaysis reveals that the diameter of bismuth ferrite
(BiFeO3) nanoparticles increases with calcination temperature
and varies from 200 to 500nm by increasing the calcined
temperature from 350˚C to 550˚C. This method avoids using
traditional high temperature and therefore could be easily
extended to other systems.
V. ACKNOWLEDGEMENT
Support from IIT Delhi and NIT Kurukshetra for SEM and
XRD characterization is gratefully acknowledged.
Fig 3: XRD patterns of BiFeO3 nanopaticles synthesized at 350˚C, 450˚C and
550 ˚C.
(a)
Mag : 10K
VI. REFERENCES
[1] W. Eerenstein, N. D. Mathur, and J. F. Scott, ‘‘Multiferroic and
Magnetoelectric Materials,’’ Nature, 442 [7104] 759–65 (2006).
[2] G. Catalan and J. Scott, ‘‘Physics and Applications of Bismuth
Ferrite,’’ Adv.Mater., 21 [24] 2463–85 (2009).
[3] P. Fischer, M. Polomska, I. Sosnowska, and M. Szymanski,
‘‘Temperature Dependence of the Crystal andMagnetic Structures of
BiFeO3,’’ J. Phys. C, 13 [10]1931–40 (1980).
[4] S. M. Selbach, T. Tybell, M. A. Einarsrud, and T. Grande, ‘‘SizeDependent Properties of Multiferroic BiFeO3 Nanoparticles,’’ Chem. Mater.,
19 [26] 6478–84(2007).
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AKGEC INTERNATIONAL JOURNAL OF TECHNOLOGY, Vol. 2, No. 2
[5] W. Eerenstein, N. D. Mathur, and J. F. Scott, “Multiferroic and
magnetoelectric materials,”Nature, vol. 442, no. 7104, pp. 759–765.
[6] P. Fischer, M. Polomska, I. Sosnowska, and M. Szymanski, “Temperature
dependence of the crystal and magnetic structures of BiFeO3,” Journal of
Physics C, vol. 13, no. 10, pp. 1931–1940, 1980.
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[8] Y. P. Wang, L. Zhou, M. F. Zhang, X. Y. Chen, J.-M. Liu, and Z. G. Liu,
“Room-temperature
saturated
ferroelectric
polarization
in
BiFeO3 ceramicssynthesized by rapid liquid phase sintering,” Applied
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Anoopshi Johari is currently an
Assistant Professor in Kumaun
Engineering College, Dwarahat,
Almora) . Did M.Tech in
Nanotechnology from National
Institute
of
Technology,
Kurukshetra in 2011 and BTech in
ECE from Ajay Kumar Garg
Engineering College, Ghaziabad in
2009.
Did six months research work on
Tin Oxide Nanowires and two
months summer project at I.I.T.
Delhi in the field of Multi ferrites.
Published a paper in International Journal of Applied Engineering Research.
Attended National Conferences and International Workshop.
[10] Y. P. Wang, L. Zhou, M. F. Zhang, X. Y. Chen, J.-M. Liu, and
Z. G. Liu, “Room-temperature saturated ferroelectric polarization in
BiFeO3
ceramics synthesized by rapid liquid phase sintering,”
Applied Physics Letters, vol. 84, no. 10, pp, 1731–1733, 2004.
Folio
BISMUTH FERRITE NANOPARTICLES
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