Exploring the Thermoelectric Performance of BaGd2NiO5Haldane Gap Materials.
One-dimensional Haldane gap materials, such as the rare earth barium chain nickelates, have received great interest due to their vibrant one-dimensional spin antiferromagnetic character and unique structure. Herein we report how these 1D structural features can also be highly beneficial for thermoelectric applications by analysis of the system CaxBaGd2-xNiO50 ≤ x ≤ 0.25. Attractive Seebeck coefficients of 140-280 μV K-1at 350-1300 K are retained even at high acceptor-substitution levels, provided by the interplay of low dimensionality and electronic correlations. Furthermore, the highly anisotropic crystal structure of Haldane gap materials allows very low thermal conductivities, reaching only 1.5 W m-1K-1at temperatures above 1000 K, one of the lowest values currently documented for prospective oxide thermoelectrics. Although calcium substitution in BaGd2NiO5increases the electrical conductivity up to 5-6 S cm-1at 1150 K < T < 1300 K, this level remains insufficient for thermoelectric applications. Hence, the combination of highly promising Seebeck coefficients and low thermal conductivities offered by this 1D material type underscores a potential new structure type for thermoelectric materials, where the main challenge will be to engineer the electronic band structure and, probably, microstructural features to further enhance the mobility of the charge carriers.
Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Narendar
http://orcid.org/0000-0002-6930-5369
N
Nasani
Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Carlos Miguel
CM
Oliveira Rocha
CICECO-Aveiro Institute of Materials, Department of Materials and Ceramic Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Andrei V
http://orcid.org/0000-0001-5814-9797
AV
Kovalevsky
Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Gonzalo
G
Otero Irurueta
Empa, Materials for Energy Conversion , Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland.|Semiconductors, ABB Switzerland Ltd. , Fabrikstrasse 3, CH-5600 Lenzburg, Switzerland.
Sascha
S
Populoh
Empa, Materials for Energy Conversion , Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland.
Philipp
P
Thiel
Materials Chemistry, Institute for Materials Science, University of Stuttgart , Heisenbergstrasse 3, DE-70569 Stuttgart, Germany.
Anke
http://orcid.org/0000-0002-7021-1765
A
Weidenkaff
Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Fernando
F
Neto da Silva
Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, University of Aveiro , 3810-193 Aveiro, Portugal.
Duncan P
http://orcid.org/0000-0001-6287-9223
DP
Fagg