80
2 – Methods and techniques
<
<
<
<
<
<
<
<
ORJı
H >ı
H LQ6FP
<
@
ı Q
ı S
ORJ D 2
:(
Figure 32 – Log of oxygen activity as a function of applied potential.
6. The equations for the lines obtained in question 5 allow us to calculate the
conductivities σ n and σ p for
.
a
and a
1
1 0
O
WE
O
WE
12
2
2
=
=
−
For a
10
O
WE
12
2
=
−
log σ n = − 0.18 # log (10
−12
) − 5.49
log σ n = − 3.32
or
4.68 10 S cm
n
4
1
σ =
−
−
#
For a
1
O
WE
2
=
log σ p = 0.27 # log (1) − 3.56
log σ p = − 3.56
or
2.75 10 S cm
p
4
1
σ =
−
−
#
Solution 2.4 – Measurement of ionic conductivity in a mixed conductor
1. The scheme for the electrochemical chain is
O 2 , Pt / YSZ / LSCo, O 2
2. The two electrodes (WE and CE) are subject to the following equilibrium:
2
1
O 2(g) + 2e m O
2−
which allows us to write
2 at the counter electrode
2
2
1 CE
CE
CE
O
e
O
2
2
μ
μ
μ
+
=
−
u
u
2 at the working electrode
2
2
1 WE
WE
WE
O
e
O
2
2
μ
μ
μ
+
=
−
u
u
2 – Methods and techniques
<
<
<
<
<
<
<
<
ORJı
H >ı
H LQ6FP
<
@
ı Q
ı S
ORJ D 2
:(
Figure 32 – Log of oxygen activity as a function of applied potential.
6. The equations for the lines obtained in question 5 allow us to calculate the
conductivities σ n and σ p for
.
a
and a
1
1 0
O
WE
O
WE
12
2
2
=
=
−
For a
10
O
WE
12
2
=
−
log σ n = − 0.18 # log (10
−12
) − 5.49
log σ n = − 3.32
or
4.68 10 S cm
n
4
1
σ =
−
−
#
For a
1
O
WE
2
=
log σ p = 0.27 # log (1) − 3.56
log σ p = − 3.56
or
2.75 10 S cm
p
4
1
σ =
−
−
#
Solution 2.4 – Measurement of ionic conductivity in a mixed conductor
1. The scheme for the electrochemical chain is
O 2 , Pt / YSZ / LSCo, O 2
2. The two electrodes (WE and CE) are subject to the following equilibrium:
2
1
O 2(g) + 2e m O
2−
which allows us to write
2 at the counter electrode
2
2
1 CE
CE
CE
O
e
O
2
2
μ
μ
μ
+
=
−
u
u
2 at the working electrode
2
2
1 WE
WE
WE
O
e
O
2
2
μ
μ
μ
+
=
−
u
u