1. Effect of Ca2+ substitution on the structural,
thermal and electrical properties of BiYO 3 for
SOFC applications
Presented by
Samita Thakur, O. P. Pandey, K. Singh
School of Physics & Materials Science
At
IV th International Conference on Advances in Energy Research
Indian Institute of Technology Bombay, Mumbai
Copyright 2013-2014
Thapar University, Patiala

2. Copyright 2013-2014

3. Conventional Energy sources
We use energy every day. Energy is needed to operate machines, to heat and
cool our homes and schools, to cook, to provide light and to take people from
place to place.
Coal
Petroleum
Copyright 2013-2014
Natural
Gas
Nuclear
power
plants
THAPAR UNIVERSITY, PATIALA
3
Wednesday, December 11,

4. Copyright 2013-2014

5. Copyright 2013-2014
Green House Emission

6. Copyright 2013-2014
Solutions to Energy Problem

7. Copyright 2013-2014
Non-conventional energy sources

8. A fuel cell is a device that
converts chemical energy
into electrical energy, water,
and
heat
through
electrochemical reactions.
The voltage generated by a
single cell is typically rather
small (< 1 volt), so many
cells are connected in series
to create a useful voltage.
Copyright 2013-2014
Fuel Cells

9. Fuel cells operation
dc current
Heat
Oxygen
Hydrogen
Water
Catalyst (Pt)
Anode (-)
H2
2H
2e
Catalyst (Pt)
Cathode (+)
Copyright 2013-2014
Membrane
(Nafion)

10. Copyright 2013-2014
Types of Fuel Cells

11. Copyright 2013-2014
Electric power for
household supply
Practical Applications of
Fuel Cells
THAPAR UNIVERSITY, PATIALA
11
Wednesday, December 11,

12. Copyright 2013-2014
THAPAR UNIVERSITY, PATIALA
12
Wednesday, December 11,

13. Merits of SOFc
Solid oxide fuel cells (SOFCs) are attracting attention due
to following reasons:
 Higher efficiency
 Negligible environmental pollution
 No liquid electrolyte
 Least material corrosion
Copyright 2013-2014
 Offers good fuel flexibility
 Internal reformation of hydrocarbons fuels
THAPAR UNIVERSITY, PATIALA
13
Wednesday, December 11,

14. Copyright 2013-2014
Components of SOFC
THAPAR UNIVERSITY, PATIALA
14
Wednesday, December 11,

15. Copyright 2013-2014
Working Principle of SOFC
THAPAR UNIVERSITY, PATIALA
15
Wednesday, December 11,

16. Limitations of SOFC
The high temperature limits
applications of SOFC units and they
tend to be rather large
Assembling
Maintenance
Design Cost & choice of material
THAPAR UNIVERSITY, PATIALA
16
Wednesday, December 11,
Copyright 2013-2014
High operating temperature also enhance
the degradation rate of materials

17. Remedies for the problems
(1)
Increase the
choices for
materials
selection
(3)
Lower the
degradation of
materials, cost
and increase
the durability
Lowering of operating temperature will also increase the
resistance of the cell and reduces the overall output. So, there is
need to develop new material s .
THAPAR UNIVERSITY, PATIALA
17
Wednesday, December 11,
Copyright 2013-2014
Lowering of
operating
temperature
(2)

18. Motivation of the present work
 The best known solid electrolytes for SOFC are ceramics with fluorite type
structure, materials based on zirconia and ceria. But its conductivity falls down
drastically below 800
C. The major drawback associated with ceria based
electrolytes is the conversion of Ce4+ to Ce3+ under SOFC anodic conditions
(reducing atmosphere). This results in high electronic conduction and chemical
expansion
 One class of materials that exhibits high oxide ion conductivity is based upon the
perovskite structure. Sr2+ doped LaInO3, LaYO3, LaGaO3 have been exploited as
S/cm.
 Depending upon the above stated facts we have chosen Bi1-xCaxYO3 (x=0, 0.1) to
study its structural, thermal and electrical properties as electrolyte for SOFC
applications.
THAPAR UNIVERSITY, PATIALA
18
Wednesday, December 11,
Copyright 2013-2014
electrolytes for their oxide ion conductivity with conductivity in the range of 10-3

19. Synthesis of Bi1-xCaxYO3 (x=0, 0.1)
Bi2O3
CaO
Y2O3
Homogeneous mixture
Calcination at 750 0C
Copyright 2013-2014
Pelletization and
sintering at 800 0C
THAPAR UNIVERSITY, PATIALA
19
Wednesday, December 11,

20. X-ray Diffraction
(b)
Intensity (counts/s)
4000
2000
0
(a)
4000
2000
0
30
40
50
60
70
80
Copyright 2013-2014
20
2 (degree)
Figure 1: X-ray diffraction pattern of (a) BiYO3 (b) Bi0.9Ca0.1YO3.
THAPAR UNIVERSITY, PATIALA
20
Wednesday, December 11,

21. Differential scanning
calorimetry/Thermogravimetric analysis
0.3
(a)
(b)
100.0
100.0
98.8
100
200
300
400
500
600
700
800
0.1
0.0
99.2
-0.1
100
Temperature ( C)
99.6
200
300
400
500
600
700
800
Temperature ( C)
Copyright 2013-2014
-0.3
0.2
Weight (%)
99.2
0.0
Microvolt (endo-down)
99.6
0.3
Weight (%)
Microvolt (endo-down)
0.6
Figure 2: DSC/TGA curve of (a) BiYO3 (b) Bi0.9Ca0.1YO3
THAPAR UNIVERSITY, PATIALA
21
Wednesday, December 11,

22. Thermal expansion coefficient
0.008
0.008
12
(b)
(a)
9
0.006
9
0.006
0.002
6
0.002
( 10-6 C-1)
3
0.004
L/L0
0.004
( 10-6 C-1)
L/L0
6
3
0
0.000
0.000
-3
100
200
300
400
500
600
700
100
800
200
300
400
500
600
700
0
800
Temperature ( C)
Copyright 2013-2014
Temperature ( C)
THAPAR UNIVERSITY, PATIALA
22
Wednesday, December 11,

23. Ac impedance spectroscopy
2
(b)
(a)
470 C
(a)
(b)
0
12000
Ln ( T)
8000
Z'' (
)
-2
-4
-6
4000
-8
0
-10
0.8
0
4000
8000
12000
16000
1.0
1.2
1.4
1.6
1.8
1000/T (K-1)
Z' ( )
Cole –Cole plot of (a) BiYO3 (b) Bi1-xCaxYO3.
Copyright 2013-2014
Arrhenius curves of (a) BiYO3 (b) Bi1-xCaxYO3.
THAPAR UNIVERSITY, PATIALA
23
Wednesday, December 11,

24. ConclusionS
 Rietveld refinement confirms that samples are single phase
and exhibit pm-3m symmetry.
 The thermogravimetric analysis shows that samples exhibit
weight loss at high temperatures due to the creation of oxygen
vacancies and bismuth vitalization.
 The TEC and conductivity shows two different slopes one
be due to the increase in oxygen vacancy concentration and
hence increase in mobility of defects at high temperatures.
THAPAR UNIVERSITY, PATIALA
24
Wednesday, December 11,
Copyright 2013-2014
below 550 C and other above that. This change in slope can

25. Copyright 2013-2014
In today’s world, solving environmental and energy
problems is an investment, not an expense
THAPAR UNIVERSITY, PATIALA
25
Wednesday, December 11,