abstract
Thermoelectric performances of cobaltite ceramics were improved by increasing grain sizes and alignment through the Electrically Assisted Laser Floating Zone method. Bi2Sr2Co1.8Oy, ceramics were directionally grown at 30 mm/h, applying external DC (0-500 mA) during the growth process. Microstructure and thermoelectric properties are significantly influenced by the external current direction and intensity. Negative currents/pole on the seed rod prevent the formation of thermoelectric phase, while positive pole on the seed rod, decreases the amount of secondary phases and increase grain orientation when compared to samples grown without current. Annealing procedure decreases secondary phases content, without modifying grain alignment. The best thermoelectric performances were obtained for samples grown with + 300 mA, reaching the highest ZT values of 0.09 at 650 degrees C. Moreover, it should be highlighted that these processed samples can be directly applied in thermoelectric modules, avoiding the long and expensive steps necessary when other preparation processes are used.
keywords
PERFORMANCE; GROWTH; MICROSTRUCTURE; ENHANCEMENT; FABRICATION; CA3CO4O9
subject category
Materials Science
authors
Ferreira, NM; Madre, MA; Torres, MA; Davarpanah, A; Amaral, V; Costa, FM; Sotelo, A
our authors
Nuno Miguel Freitas Ferreira
Post-Doc FellowshipGroups
acknowledgements
Authors acknowledge the support of i3N (UIDB/50025/2020 & UIDP/50025/2020) and CICECO-Aveiro Institute of Materials (UID/CTM/50011/2020), financed by FCT/MEC and FEDER under the PT2020 Partnership Agreement.; This work is funded by national funds (OE), through FCT Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.; A. Sotelo, M. A. Madre, and M. A. Torres acknowledge the MINECOFEDER (MAT2017-82183-C3-1-R), and the Gobierno de Aragon (Grupo de Investigacion T 54-17 R)for funding.