Magnetic and Dielectric Properties of
DyxSr2-xTiMnO6 (x = 0, 0.5) oxides
Rajib Mondal1, Tapas Ghosh1, R. Nirmala1* and A. K. Nigam2
1
Department of Physics, Indian Institute of Technology Madras, Chennai 600 036, India
2
Tata Institute of Fundamental Research, Mumbai 400 005, India
*nirmala@iitm.ac.in, Tel.: +91-4422574888; Fax: +91-4422574852
Abstract
Polycrystalline oxides Sr2TiMnO6 and Dy0.5Sr1.5TiMnO6
crystallize in Cubic structure (Space group Fm3m ) at room
temperature. While Sr2TiMnO6 orders magnetically at ~ 45 K
and further at ~15 K, Dy0.5Sr1.5TiMnO6 shows no magnetic
transition down to 5 K. The magnetization vs field data at 5
K, suggest antiferromagnetic-like behavior and Dy
substitution enhances the magnetic moment value. Silver
painted pellets of both oxides show colossal dielectric
constant ~104 over a large frequency range.
Keywords: Oxides, dielectrics, magnetic properties.
Introduction
Study of colossal dielectric constant (CDC)
materials is of special interest because of their wide
applications in microelectronics [1]. Manganite like
double perovskite oxide Sr2TiMnO6 is one of the CDC
materials that show interesting dielectric and magnetic
properties. The origin of such high dielectric constant is
often attributed to the Maxwell-Wagner (MW)
relaxation mechanism [1]. In addition, Sr2TiMnO6
shows interesting magnetic properties which is signified
by the presence of ferromagnetic-like ordering at ~ 45 K
(TC) followed by another transition at ~ 15 K (TN) [2].
The present work aims to study the effect of rare earth
ion substitution at Sr-site of Sr2TiMnO6 on magnetic
and dielectric properties.
group, Fm3m ). Magnetization data of Dy0.5Sr1.5TiMnO6
in 5 kOe do not reveal any transition down to 5 K.
Inverse paramagnetic susceptibility follows Curie-Weiss
law with negative θp value of ~ -6.2 K and effective
magnetic moment ~9.1 μB. Magnetization vs field at 5 K
in 70 kOe field is ~3.35 μB and is about one order larger
than parent Sr2TiMnO6. Ag-painted pellets of
Sr2TiMnO6 and Dy0.5Sr1.5TiMnO6 show real part of
dielectric constant to be ~20000 and 16000, respectively
at 1 kHz frequency at 300 K. The origin of such high
dielectric constant behavior may be explained in terms
of intrinsic hopping conduction and extrinsic MW
relaxation mechanism.
Experimental details
Polycrystalline DyxSr2-xTiMnO6 (x = 0, 0.5)
oxides were prepared by solid state reaction and were
characterized by powder X-ray diffraction (XRD),
scanning electron microscopy and energy dispersive Xray analysis. Magnetic measurements were carried out
in the temperature range of 5 K - 300 K and in fields up
to 70 kOe. Dielectric measurements were carried out in
the frequency range of 1 kHz – 1 MHz and in the
temperature range from 125 K – 300 K.
Results and discussion
Room temperature powder XRD patterns of
DyxSr2-xTiMnO6 (x = 0, 0.5) confirm the phase purity
and the samples crystallize in cubic structure (space
Fig. 1: - Dielectric constant vs frequency of Sr2TiMnO6
and Dy0.5Sr1.5TiMnO6 at 300 K [Inset: Magnetization vs
Field of Sr2TiMnO6 and Dy0.5Sr1.5TiMnO6 at 5 K]
Conclusions
Magnetic and dielectric properties of DyxSr2(x = 0, 0.5) oxides are investigated and both of
them show large room temperature dielectric constant
values.
xTiMnO6
References
[1] K. R. S. Preethi Meher et al. J. Appl. Phys. 105 (2009)
034113.
[2] Jagat Lamsal et al. J. Appl. Phys. 109 (2011) 07E329.