Significant enhancement of the thermoelectric performance in Ca3Co4O9 thermoelectric materials through combined strontium substitution and hot-pressing process

Torres, M.A. (Universidad de Zaragoza) ; Costa, F.M. ; Flahaut, D. ; Touati, K. ; Rasekh, S. ; Ferreira, N.M. ; Allouche, J. ; Depriester, M. ; Madre, M.A. (Universidad de Zaragoza) ; Kovalevsky, A.V. ; Diez, J.C. (Universidad de Zaragoza) ; Sotelo, A. (Universidad de Zaragoza)

Resumen: This work explores the possibilities for a further enhancement of the thermoelectric properties of Ca3Co4O9 by Sr-doping combined with hot-pressing. Modified hot-pressing process resulted in highly-textured and dense ceramics. Sr-doping significantly improves electrical properties, resulting in extremely large power factor (1.2 mW/K2m at 800 °C) due to simultaneous electrical resistivity decrease and Seebeck coefficient increase. The main effect on cumulative electrical performance is provided by the Seebeck coefficient, reaching 270µV/K at 800 °C. XPS revealed relatively high average cobalt oxidation state at room temperature (+3.3), compared to materials produced by conventional sintering. The results of combined XPS and Auger electron spectroscopy emphasize the importance of high densification in Ca3Co4O9-based ceramics for preventing phase decomposition and interaction with CO2 and moisture. Still, despite the exceptional electrical performance, the calculated figure-of-merit (estimated as 0.29 at 800 °C) is around the best reported in the literature due to a high thermal conductivity (4.4 W/K m at room temperature).

Idioma: Inglés

DOI: 10.1016/j.jeurceramsoc.2018.12.049

Año: 2019

Publicado en: Journal of the European Ceramic Society 39, 4 (2019), 1186-1192
ISSN: 0955-2219

Factor impacto JCR: 4.495 (2019)

Categ. JCR: MATERIALS SCIENCE, CERAMICS rank: 1 / 28 = 0.036 (2019) - Q1 - T1

Factor impacto SCIMAGO: 1.164 - Materials Chemistry (Q1) - Ceramics and Composites (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/T54-17R
Financiación: info:eu-repo/grantAgreement/ES/MINECO-FEDER/MAT2017-82183-C3-1-R

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Expresión Gráfica en Ing. (Dpto. Ingeniería Diseño Fabri.)
Área (Departamento): Área Cienc.Mater. Ingen.Metal. (Dpto. Ciencia Tecnol.Mater.Fl.)