Enhancing the thermoelectric power factor of Sr 0.9 Nd 0.1 TiO 3 through control of the nanostructure and microstructure
Donor-doped SrTiO 3 ceramics are very promising n-type oxide thermoelectrics. We show that significant improvements in the thermoelectric power factor can be achieved by control of the nanostructure and microstructure. Using additions of B 2 O 3 and ZrO 2 , high density, high quality Sr 0.9 Nd 0.1 T...
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Published in | Journal of materials chemistry. A, Materials for energy and sustainability Vol. 6; no. 48; pp. 24928 - 24939 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
11.12.2018
|
Online Access | Get full text |
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Summary: | Donor-doped SrTiO
3
ceramics are very promising n-type oxide thermoelectrics. We show that significant improvements in the thermoelectric power factor can be achieved by control of the nanostructure and microstructure. Using additions of B
2
O
3
and ZrO
2
, high density, high quality Sr
0.9
Nd
0.1
TiO
3
ceramics were synthesised by the mixed oxide route; samples were heat treated in a single step under reducing atmosphere at 1673 K. Synchrotron and electron diffraction studies revealed an
I
4/
mcm
tetragonal symmetry for all specimens. Microstructure development depended on the ZrO
2
content; low level additions of ZrO
2
(up to 0.3 wt%) led to a uniform grain size with transformation-induced sub-grain boundaries. HRTEM studies showed a high density of dislocations within the grains; the dislocations comprised (100) and (110) edge dislocations with Burger vectors of
d
(100)
and
d
(110)
respectively. Zr doping promoted atomic level homogenization and a uniform distribution of Nd and Sr in the lattice, inducing greatly enhanced carrier mobility. Transport property measurements showed a significant increase in the power factor, mainly resulting from the enhanced electrical conductivity while the Seebeck coefficients were unchanged. In optimised samples a power factor of 2.0 × 10
−3
W m
−1
K
−2
was obtained at 500 K. This is an ∼30% improvement compared to the highest values reported for SrTiO
3
-based ceramics. The highest
ZT
value for Sr
0.9
Nd
0.1
TiO
3
was 0.37 at 1015 K. This paper demonstrates the critical importance of controlling the structure at the atomic level and the effectiveness of minor dopants in enhancing the thermoelectric response. |
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ISSN: | 2050-7488 2050-7496 |
DOI: | 10.1039/C8TA07861K |