Hybrid microwave processing of Ca3Co4O9 thermoelectrics
authors Miyazawa, K; Amaral, F; Kovalevsky, AV; Graca, MPF
nationality International
journal CERAMICS INTERNATIONAL
author keywords Thermoelectrics; Ca3Co4O9; Hybrid microwave sintering
keywords GRAIN-SIZE; CERAMICS; PERFORMANCE; TEXTURE; OXIDES; DENSIFICATION; SUBSTITUTION; ENHANCEMENT; IMPROVEMENT; SCATTERING
abstract In this study, hybrid microwave sintering of Ca3Co4O9 thermoelectric materials was implemented for the first time. Thermoelectric properties of samples sintered in different conditions and in conventional electrical furnace, using the same temperatures and dwell times, were assessed and compared. Microwave processing was found to promote densification and grain texturing in Ca3Co4O9 bulk ceramics, leading to a significant increase of the electrical conductivity. Seebeck coefficient and thermal conductivity were essentially unaffected by the microstructural changes. Prolonged exposure to microwave radiation at 800 degrees C led to partial phase decomposition and consequent formation of Ca3Co2O6 and Co3O4 impurities, with minor effect on the charge transport. Still, the significant presence of residual porosity suggests the need for further optimization of powder and microwave processing conditions. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0272-8842
year published 2016
volume 42
issue 8
beginning page 9482
ending page 9487
digital object identifier (doi) 10.1016/j.ceramint.2016.03.015
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000374811600022
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journal impact factor 3.057
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