Magnetism in nanocrystalline BaTiO3 and role of TiO6 Octahedra
S Ramakanth 1, K C James Raju 1, 2,*
1
Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad,
Hyderabad 500046, India
2
School of Physics, University of Hyderabad, Hyderabad, 500046, India
*
kcjrsp@uohyd.ernet.in
Abstract: The understanding magnetic properties of nanocrystalline BaTiO3 (nc-BTO) is of current interest.
We have prepared the samples by sol-gel method. The charge transfer is observed for sample A whereas sample
B don’t show charge transfer evidence. A clear ferromagnetic transition and higher magnetic coercivity is
observed for charge transfer involved samples. Hence it is essential to include the charge transfer induced
electronic states in explaining the observed magnetism in this kind of materials.
2. EXPERIMENTAL
The BTO nanoparticles were prepared by sol-gel
method [3, 4], by taking barium acetate and titanium
isopropoxide as precursor chemicals. 0.0067 mole of
barium acetate is dissolved in 40ml of propanoic acid
and stirred until it gets completely dissolved. Then
same mole of titanium isopropoxide was dissolved
into 10 ml of ethyl alcohol in the presence of N2
atmosphere. Finally, this solution is added drop by
drop into dissolved barium acetate in the N2
atmosphere. Slowly, the sol is heated to 110o C.
Finally 0.02 mole of acetyl acetone is added and
stirred for 3hrs. The prepared sol was dried at 200oC
for 10 hrs. This dry powder is then calcined at 650oC
and at 800oC. The 650oC calcined sample is sintered at
1000 oC for 1hr (sample A). The 800oC sample is
named as sample B. The M-H hysteresis loop and FCZFC measurements were carried out using, vibrating
sample magnetometer (Quantum design instruments).
3. RESULTS AND DISCUSSION
The study of magnetic properties nonmagnetic
oxides is currently most studied. But the origin of
magnetism is not yet clear accurately. We have
explained the magnetism of nc-BTO using charge
transfer effects in the previous studies [5]. The M-H
measurements show ferromagnetic behavior with
magnetization ~ (2x10-3emu/gm) for these two
samples. The coercivity values of 380Oe and 28Oe are
observed for sample A and B respectively. The FCZFC measurements were carried out at 1000 Oe.
Sample A show a transition temperature of 62oC,
where as sample B show lower FC-ZFC bifurcation
with higher bifurcation temperature.
M(emu/gm)
0.0050
0.0045
0.0040
M(emu/gm)
1. INTRODUCTION
The multiferroic materials have got considerable
attention scientific society due to the existence of both
ferroelectric and ferromagnetic order in the same
material. The existence these both orders is explained
in fundamental multiferroic like BiFeO3 etc [1]. But
the existence of these two orders in materials like
BTO is under developed. BTO is prototype
ferroelectric material. Hence the study of origin of
magnetism in this attracted instead of multiferroicity
of it. There are previous reports on the magnetic
properties of this material by C N Rao et.al [2]. There
are many effects which come into picture when the
material is of nano dimension.
Here we have prepared two BTO samples named as
sample A and sample B. The photoluminescence (PL)
evidences the presence of charge transfer effects in
sample A. Whereas the sample B don’t show charge
transfer effects (not shown here) in spite of having
nanosize.
0.0035
0.010
0.005
0.000
-8000 -4000 0
0.0030
-0.005
0.0025
A
B
4000 8000
H(Oe)
-0.010
0.0020
0.0015
0.0010
0.0005
0
50
100
150
200
Temperature(K)
250
300
Fig.1. ZFC-FC curves for sample A and B. Inset
shows the M vs H curves for these two samples.
The EDAX measurements (not shown here), rule out
the existence magnetic elements like Fe in the sample.
ACKNOWLEDGEMENT
We Acknowledge DRDO for their financial support,
and UGC for providing VSM based Instruments in
Centre for Nano Technology.
REFERENCES
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067601.
[2]. R. V. K. Mangalam al, Solid state Comm. 149
(2009) 1.
[3]. X. Zhang et al, J. Am. Ceram. Soc. 93 (2010)
3591.
[4]. S. Otsuk et al, J. Am. Ceram. Soc. 82 (1999)
1676.
[5]. S. Ramakanth et.al, solid state comm. 187 (2014)
59.