abstract
Oxide materials based on calcium manganite show clear prospects as thermoelectrics, provided by their stability at high temperatures and inherent flexibility in tuning the relevant electrical and thermal transport properties. Donor-doped CaMnO3 is an n-type semiconductor with a perovskite structure and relatively high thermoelectric performance. In this work, the precursor powders have been modified through potassium carbonate additions to produce Ca0.9Gd0.1MnO3 pellets without the usual delamination problems occurring during the compaction process. In order to demonstrate the relevant effects, several samples with different amounts of potassium carbonate (0-15wt%) have been prepared. The results showed that potassium additions significantly facilitate the compaction procedure, while also improving the thermoelectric performances. The results also highlight the importance of porosity control for improving ZT, by decreasing the thermal conductivity without reduction of the electrical performance. The highest ZT values were observed for the samples processed at 15wt% of potassium carbonate addition, exhibiting an improvement at least 30% at 800 degrees C when compared to the pure samples.
keywords
CAMNO3; MICROSTRUCTURE; CONDUCTIVITY
subject category
Materials Science
authors
Ferreira, NM; Ferro, MC; Sarabando, AR; Ribeiro, A; Davarpanah, A; Amaral, V; Madre, MA; Kovalevsky, AV; Torres, MA; Costa, FM; Sotelo, A
our authors
Amin Davarpanah
PhD Student
Andrei Kavaleuski
Principal Researcher
Artur Ricardo Mesquita Sarabando
research grante
Marta Ascenção Carmona Ferro
Laboratory Officer
Nuno Miguel Freitas Ferreira
Post-Doc Fellowship
Vitor Brás Sequeira Amaral
Full professorGroups
G2 - Photonic, Electronic and Magnetic Materials
G3 - Electrochemical Materials, Interfaces and Coatings
acknowledgements
N.M. Ferreira, A.V. Kovalevsky and FM Costa acknowledge the support of i3N (UID/CTM/50025/2013) and CICECO-Aveiro Institute of Materials (UID/CTM/50011/2013), financed by FCT/MEC and FEDER under the PT2020 Partnership Agreement. The support from FCT (Portugal) grant SFRH/BPD/111460/2015, and the funding that allowed a scientific mission to Zaragoza to perform the present work, is also acknowledged. A. Sotelo, M. A. Madre, J. C. Diez, and M. A. Torres acknowledge the Gobierno de Aragon (Grupo de Investigacion T 54-17 R), and the MINECO-FEDER (MAT2017-82183-C3-1-R) for funding.