Tuning thermoelectric properties of Ca 0.9 Gd 0.1 MnO 3 by laser processing
- PDF / 1,915,148 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 25 Downloads / 197 Views
Tuning thermoelectric properties of Ca0.9Gd0.1MnO3 by laser processing N. M. Ferreira1,* A. Sotelo3
, A. R. Sarabando2, M. C. Ferro2, M. A. Madre3, O. J. Dura4, and
1
I3N, Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal Department of Materials and Ceramic Engineering, CICECO - Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal 3 ICMA, CSIC-Universidad de Zaragoza, Zaragoza, Spain 4 Applied Physics Department, University of Castilla-La Mancha, Ciudad Real, Spain 2
Received: 15 June 2020
ABSTRACT
Accepted: 4 September 2020
Donor-doped CaMnO3 is an n-type semiconductor with perovskite structure, being considered as a potential n-type leg in thermoelectric modules. This oxide presents stability at high temperatures and allows tuning the relevant electrical and thermal transport properties through doping. In this work, Ca0.9Gd0.1MnO3 precursors have been prepared to produce fibres through the laser floating zone technique using different pulling rates. However, as-grown fibres did not present thermoelectric properties due to the presence of high amounts of secondary phases, leading to very high electrical resistivity values. The results have highlighted the importance of annealing procedures to reduce electrical resistivity, due to the decrease of secondary phases amount, and producing promising thermoelectric performances. The annealed samples present higher ZT values when the growth rate is decreased, reaching around 0.22 for the lowest growth rate, which is very close to the best values reported in the literature for these materials. Moreover, this procedure possesses an additional advantage considering that these samples can be directly used as n-type legs in thermoelectric modules for high-temperature applications. However, further studies should be made to determine the optimal amount of dopant.
Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction The capacity of converting waste heat into electric energy by thermoelectric (TE) materials, with no needs of moving parts and without producing carbon dioxide gas, toxic substances, or other emissions, are
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10854-020-04428-x
gaining scientific and industrial interest. With this purpose, different materials are proposed to be used in thermoelectric devices. Transition oxides-based ceramics are one of the most promising, due to their high thermal and chemical stability when working under oxidizing atmospheres, at high temperatures
J Mater Sci: Mater Electron
[1]. Amongst the n-type semiconductor oxides, CaMnO3 is regarded as one of the most suitable ones [2–8]; however, this compound possesses limited TE performances due to its low carrier concentration [1–6]. Consequently, many studies have been carried out to improve its thermoelectric properties using dopants and different preparation techniques [2–6, 9–11]. These studies are essentially focused on the improvement of electrical conductivity, without d
Data Loading...