Enhancing the thermoelectric performance of cold sintered calcium cobaltite ceramics through optimised heat-treatment
Yu, Jincheng; Nelo, Mikko; Liu, Xiaodong; Shao, Shouqi; Wang, Bing; Haigh, Sarah J.; Jantunen, Heli; Freer, Robert (2022-03-14)
Yu, J., Nelo, M., Liu, X., Shao, S., Wang, B., Haigh, S. J., Jantunen, H., & Freer, R. (2022). Enhancing the thermoelectric performance of cold sintered calcium cobaltite ceramics through optimised heat-treatment. Journal of the European Ceramic Society, 42(9), 3920–3928. https://doi.org/10.1016/j.jeurceramsoc.2022.03.017
© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
https://creativecommons.org/licenses/by/4.0/
https://urn.fi/URN:NBN:fi-fe2022091358851
Tiivistelmä
Abstract
Cold sintering is a promising technology for preparing electronic materials, enabling densification at low temperature, but rarely employed for thermoelectrics. Herein, high-quality Ca2.7Bi0.3Co3.92O9+δ ceramics were synthesised by a combination of cold sintering and annealing processes. Stoichiometric mixtures of raw materials were calcined once or twice at 1203 K for 12 h in air, and then cold sintered at 673 K for 60 min under a pressure of 85 MPa, followed by annealing at 1203 K for 12 h or 24 h in air. The effects of the calcination processes and annealing conditions on the thermoelectric performance of cold sintered samples were investigated. By optimising heat-treatment, the formation of secondary phases, texture development and porosity were controlled, leading to enhanced electrical conductivity and reduced thermal conductivity. Consequently, at 800 K there was 85% increase in power factor and 35% increase in ZT (value of 0.15) compared to previous studies.
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