Vol.:(0123456789) 1 3
J Mater Sci: Mater Electron
DOI 10.1007/s10854-017-7667-y
Structural, dielectric, impedance and modulus spectroscopy
of Bi
2
NdTiVO
9
ferroelectric ceramics
Prabhasini Gupta
1
· Rajib Padhee
1
· P. K. Mahapatra
1
· R. N. P. Choudhary
1
Received: 23 June 2017 / Accepted: 5 August 2017
© Springer Science+Business Media, LLC 2017
1 Introduction
Nowadays, there is a huge craze for design and develop-
ment of new materials which show the properties required
for device fabrication. In the process, a large number of
oxide materials of diferent nature, structure and phenom-
enon, such as, piezoelectric, ferroelectric and ferromagnetic
have been developed. Out of these, some lead (Pb)-based
oxide ceramics including lead zirconate titanate (PbZrTiO
3,
PbMgNbO
3,
etc.) show excellent electronic and electro-
optic properties. But, due to toxicity of lead, serious steps
are being taken to replace these materials with eco-friendly
(non-lead) compounds. Thus, in order to get a lead-free
ferroelectric material with high ferroelectric and related
properties, bismuth layer structured ferroelectric (BSLF) of
Aurivillius family was discovered in 1949 [1]. Since then,
a large number of (BSLF) materials were investigated and
reported. Aurivillius family has a layer structure with a gen-
eral chemical formula (Bi
2
O
2
)
2+
(A
n−1
B
n
O
3n+1
)
2−
, where
(Bi
2
O
2
)
2+
is a bismuth oxide layer, (A
n−1
B
n
O
3n+1
)
2−
is a
pseudo perovskite layer and n is the number of BO
6
octa-
hedra in the perovskite layers (n = 1–5). The A-site can be
occupied by mono-di- or trivalent element (s) (i.e., Bi
3+
,
Ba
2+
, Sr
2+
, Ca
2+
, Pb
2+
, K
+
, Na
+
, Rare earths, etc.,) in the
12-fold coordination number and the B-site by transition
element (i.e., Fe
3+
, Mn
3+
, Ti
4+
, Nb
5+
, Ta
5+
, Mo
6+
, V
5+
and
W
6+
, etc.) of the sixfold coordination numbers [2–4]. The
oxygen octahedral blocks, sandwitched between the bismuth
oxide layers, are responsible for the ferroelectric behavior
[5]. Some members of the Aurivillus family have engraved
the attention of many researchers because of their low oper-
ating voltage, excellent switching speed, high retentivity and
small leakage current density. These characterestics of the
materials are best suited for some devices including non-
volatile ferroelectric random access memories (FRAM) [6].
Abstract Detailed studies of electrical and resistive prop-
erties of Bi
2
NdTiVO
9
(a member of the Aurivillius family),
fabricated by a method of standard high-temperature solid-
state reaction, are discussed here. The compound crystallizes
in the orthorhombic crystal structure. The surface morphol-
ogy studies show a uniform distribution of grains. The single
semicircle of the complex impedance plot and the value of
the nonlinear coefcient of the J∼E graph suggest that the
polarization in the material is due to grain efect only. The
semiconducting nature (i.e., negative temperature coefcient
of resistance) is observed in the temperature dependence
of bulk resistance and J–E characteristics of the sample.
The frequency dependence of impedance and electrical
modulus of the material shows the existence of non Debye-
type of relaxation. The activation energy obtained from the
relaxation and conduction processes is found to support
the activation of oxygen vacancies in the compound. An
analysis of ac conductivity, based on the Jonscher’s power
law, suggests that the conduction mechanism in the mate-
rial can be explained using CBH model (i.e., hopping of
oxygen ions between vacancies). The nature and existence
of electric feld dependent polarization (P–E hysteresis loop)
at room temperature show that the material has ferroelectric
property.
* Prabhasini Gupta
prabhasinigupta@gmail.com
1
Multifunctional materials Research Laboratory,
Department of Physics, Siksha ‘O’ Anusandhan University,
Bhubaneswar 751030, Odisha, India