Microstructural Influence on Thermoelectric Properties of CaMnO3 Ceramics

• Autor(a) principal: Torres,Samanta de O. A.
• Data de Publicação: 2020
• Outros Autores: Thomazini,Daniel, Balthazar,Gabriel P., Gelfuso,Maria V.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Materials research (São Carlos. Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392020000500220
• topic: Calcium manganite; thermoelectric; sintering time

Thermoelectric properties of pure polycrystalline CaMnO3 ceramics were significantly enhanced by increasing sintering holding time from 1 to 24 h. The Seebeck coefficient values were reduced while the sintering holding time was increased, and the DC electrical conductivity was enhanced from 255 S/m to 1.748 S/m. This same effect was observed in electronic thermal conductivity, increasing from 5x10-3 to 3.5x10-2W/m K, whereas the lattice thermal conductivity decreased from 5.0 to 4.0 W/m K at 873K. Overall, CaMnO3 ceramic sintered for 24 h demonstrated the best performance, which presented a Figure-of-Merit value of about 0.03. The grain size of the samples ranged from 2.79 µm to 6.45 µm, due to the sintering holding time, directly influencing the high-temperature thermoelectric properties of CaMnO3 ceramics.