Structural, thermal, electrical and morphological characterization of
(Bi
2
O
3
)
1xy
(Sm
2
O
3
)
x
(Yb
2
O
3
)
y
nanostructures prepared by solid state
synthesis
Yasin Polat
a, *
,Yılmaz Da
gdemir
b
, Mehmet Arı
b
a
Institute of Science, Erciyes University, 38039 Kayseri, Turkey
b
Department of Physics, Erciyes University, 38039 Kayseri, Turkey
article info
Article history:
Received 3 June 2016
Received in revised form
10 August 2016
Accepted 20 September 2016
Available online 20 September 2016
Keywords:
Ceramics
Nanostructures
Oxides
Chemical synthesis
Electrical conductivity
abstract
In the present work, the ternary system of (Bi
2
O
3
)
1xy
(Sm
2
O
3
)
x
(Yb
2
O
3
)
y
was investigated. For the
production and stabilization of the fcc-type solid solution, nano-Sm
2
O
3
and nano-Yb
2
O
3
were doped into
nano-Bi
2
O
3
by solid-state synthesis techniques. The XRD results showed that the crystallographic
structure of the samples had displayed a fluorite type face-centered cubic d-Bi
2
O
3
phase. The phase
stability was also checked by the DTA measurements. The temperature dependent electrical conductivity
results revealed that the maximum electrical conductivity observed for the sample of the nanostructure-
(Bi
2
O
3
)
0.8
(Sm
2
O
3
)
0.1
(Yb
2
O
3
)
0.1
system was 5.39 10
2
(ohm.cm)
1
at 650
C. The results also show that
the lowest activation energy was 0.7062 eV and the lowest crystallite size was 31.62 nm for the nano-
structure-(Bi
2
O
3
)
0.75
(Sm
2
O
3
)
0.1
(Yb
2
O
3
)
0.15
system. Consequently, the face-centered cubic stable d-phase-
(Bi
2
O
3
)
0.8
(Sm
2
O
3
)
0.1
(Yb
2
O
3
)
0.1
is the optimal dopant amount due to the relatively good stability and
oxygen ionic conductivity obtained, which are two of our major concerns for the electrolyte layer of solid
oxide fuel cells (SOFCs).
© 2016 Elsevier B.V. All rights reserved.
1. Introduction
This research focuses on candidate electrolyte materials for
SOFCs which can directly produce electricity from the chemical
energy of fuels with high efficiency, without mechanical processes.
One of the constituents of a SOFC is the ion-conductive electrolyte
layer that separates the anode and cathode electrodes. Electrolytes
are an essential layer to transmit sufficient ionic conductivity be-
tween the anode and cathode electrodes. Until now, ZrO
2
-based
type systems have been widely used as electrolytes in SOFCs which
need high operating temperatures (1000e1100
C) to obtain suffi-
cient output power [1e5]. On the other hand, the d-Bi
2
O
3
-based
electrolyte has a high level of conductivity at an intermediate
temperature range (600e800
C) as compared to ZrO
2
-based type
solid electrolytes [6]. d-Bi
2
O
3
based electrolytes have been reported
to be potential electrolytes for intermediate temperature SOFCs (IT-
SOFCs). Moreover, Bi
2
O
3
with a lower melting point (824
C) is also
generally used as electrolyte which can help to increase the
transmission of oxide ions at lower temperatures.
Over the last decade, many studies have been performed on the
synthesis of single-doped Bi
2
O
3
-based electrolytes that have high
ionic conductivity but these materials have structural stability
deficiency [6e10]. Lately, several researches [11e 18] have reported
that the oxide ionic conductivities and structural stabilities of
double-doped Bi
2
O
3
-based electrolytes were found to be higher
and better than those of single-doped systems. Dap cevi c et al. [4]
found that (Bi
0.80
Tm
0.20
)
2
O
3
exhibits high conductivity
(0.117 S cm
1
at 550
C) with the following activation energies:
0.38 eV above 550
C and 1.27 eV below 550
C. Vasundhara et al.
[9] found the highest conductivity value as 1.8 10
3
(ohm.cm)
1
at 627
C and activation energy as 1.01 eV for the
Yb
0.50
Bi
0.50
O
1.50
binary system. Jaiswal et al. [11] focused on the
nanosized powders of compositions; Bi
0.8
Er
0.2
O
1.5
(ESB) and
Ce
0.85
La
0.15
O
1.925
(CLO) were investigated by the citrateenitrate
auto combustion method. They found that Ce
0.85
La
0.15
O
1.925
with
0.5 wt % of ESB exhibits the maximum conductivity of
1.41 10
2
S cm
1
at 600
C of all the compositions.
The Bi
2
O
3
system displays an exceptionally abundant variety of
polymorphs. These abundant varieties are represented by mono-
clinic aBi
2
O
3
, tetragonal bBi
2
O
3
, cubic-bcc gBi
2
O
3
, cubic-fcc
* Corresponding author.
E-mail address: yasinpolat2001@hotmail.com (Y. Polat).
Contents lists available at ScienceDirect
Current Applied Physics
journal homepage: www.elsevier.com/locate/cap
http://dx.doi.org/10.1016/j.cap.2016.09.013
1567-1739/© 2016 Elsevier B.V. All rights reserved.
Current Applied Physics 16 (2016) 1588e1596