Improvement of thermoelectric properties of Ca0.9Gd0.1MnO3 by powder engineering through K2CO3 additions

authors	Ferreira, NM; Ferro, MC; Sarabando, AR; Ribeiro, A; Davarpanah, A; Amaral, V; Madre, MA; Kovalevsky, AV; Torres, MA; Costa, FM; Sotelo, A
nationality	International
journal	JOURNAL OF MATERIALS SCIENCE
keywords	CAMNO3; MICROSTRUCTURE; CONDUCTIVITY
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.
publisher	SPRINGER
issn	0022-2461
isbn	1573-4803
year published	2019
volume	54
issue	4
beginning page	3252
ending page	3261
digital object identifier (doi)	10.1007/s10853-018-3058-x
web of science category	Materials Science, Multidisciplinary
subject category	Materials Science
unique article identifier	WOS:000452502500039