Dielectric, Ferroelectric and Magnetic Studies of
Sm/Ni Modified Bi4Ti3O12 Ceramics
Sumit Bhardwaj1, Joginder Paul1*, Kuldeep Kumar Sharma2, Ravi Kumar1, 3
1
Centre for Material Science and Engineering, National Institute of Technology, Hamirpur (H.P.)-177005, India
2
Department of Physics, National Institute of Technology, Hamirpur (H.P.)-177005, India
3
Beant college of Engineering and Technology, Gurdaspur (PB.)-143521, India
*
Corresponding author’s e-mail: jp_phy@yahoo.in, Tel.: +91-9418179401; Fax: +91-1972-223834
Abstract: Lead free Bi4-xSmxTi3-xNixO12 (x=0.0, 0.03) ceramics have been synthesized by solid state route. X-ray diffraction
(XRD) pattern confirms the formation of single phase orthorhombic structure. Frequency dependent dielectric constant and loss
tangent was found to decrease with substitution, due to reduction in interfacial polarization. The remanant polarization (2P r) value
was found to increase with substitution. The M-H curve shows the presence of weak ferromagnetism in the system. These
materials can be used for future multiferroic applications.
Keywords: Ceramics, microstructure, dielectric constant, ferroelectricity, ferromagnetism.
Introduction
Materials with two or more ferroic orders such
as ferroelectric, ferromagnetic or ferroelastic are known
as multiferroic materials. These materials can be used in
multiple state memories, data storage devices, sensors
and transducers [1]. The mechanism for ferroelectricity
and ferromagnetism are mutually exclusive to each
other, hence existence of single phase multiferroic
materials are very rare. Among the lead free materials
bismuth titanate (BIT) is one of the ferroelectric
materials with high Tc (675 ºC). Some reports are
available in literature related to multiferroic nature of
BIT [2]. In this paper, we have presented the dielectric,
ferroelectric and magnetic studies of Sm/Ni substituted
BIT ceramics.
Results and Discussion
Fig. 1(a) shows the X-ray diffraction pattern of
the prepared samples. All the diffraction peaks are
indexed to pure bismuth titanate having orthorhombic
unit cell (JCPDS card No. 89-7500). Lattice parameters
were calculated and it is found that orthorhombic
distortion increases with substitution. Fig. 1(b) and (c)
shows the FE-SEM images for x=0.0 and x=0.03
respectively. Plate like grain growth is observed for
both the samples and grain size is found to increase with
substitution. Fig. 2(a) shows the frequency dependent
dielectric constant and loss tangent (shown in inset) and
is found to decrease with substitution. This decrease is
attributed to the increase in grain size as observed in
FE-SEM images, which results in decrease in interfacial
polarization. Fig. 2(b) shows the room temperature P-E
loops for both the samples. The 2Pr and 2Ec values were
found to increase with substitution. This can be due to
the increased orthorhombic distortions and reduction in
domain wall pinning. Fig. 2(c) demonstrates the M-H
curve of both the samples. Pure BIT shows the
diamagnetic nature of the material. Upon Ni2+
substitution, observation of S-type non-saturated curve
shows the magnetic nature of the material with weak
ferromagnetism. This can be ascribed to the existence of
F-centre exchange mechanism in the system.
Fig. 1 (a) XRD, SEM images (b) x=0.0(c) x=0.03.
Fig. 2 (a) Dielectric constant and loss tangent, (b) P-E
hysteresis loop, (c) M-H curve.
References
[1] H. Schmid, “Multi-ferroic magnetoelectrics”,
Ferroelectrics, 162, (1994), 317-338.
[2] X. Q. Chen, F. J. Yang, W. Q. Cao, D. Y. Wang,
and K. Chen, “Room-temperature magnetoelectric
coupling in Bi4(Ti1Fe2)O12−δ system” J. Phys. D: Appl.
Phys., 43, (2010), 065001.