Improvement of thermoelectric properties of Ca0.9Gd0.1MnO3 by powder engineering through K2CO3 additions
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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 (0–15 wt%) 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 15 wt% of potassium carbonate addition, exhibiting an improvement at least 30% at 800 °C when compared to the pure samples.
N.M. Ferreira, A.V. Kovalevsky and FM Costa acknowledge the support of i3 N (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.
- 12.Sotelo A, Costa FM, Ferreira NM, Kovalevsky A, Ferro MC, Amaral VS, Amaral JS, Rasekh Sh, Torres MA, Madre MA, Diez JC (2016) Tailoring Ca3Co4O9 microstructure and performances using a transient liquid phase sintering additive. J Eur Ceram Soc 36:1025–1032. https://doi.org/10.1016/j.jeurceramsoc.2015.11.024 CrossRefGoogle Scholar
- 13.https://pubchem.ncbi.nlm.nih.gov/compound/calcium_carbonate#section=Boiling-Point. Last visit March 2018
- 16.Rosić M, Kljajević LJ, Jordanov D, Stoiljković M, Kusigerski V, Spasojević V, Matović B (2015) Effects of sintering on the structural, microstructural and magnetic properties of nanoparticle manganite Ca1-xGdxMnO3 (x = 0.05; 0.1; 0.15; 0.2). Ceram Int 41:14964–14972. https://doi.org/10.1016/j.ceramint.2015.08.041 CrossRefGoogle Scholar
- 18.Noorsyakirah A, Mazlan M, Afian OM, Aswad MA, Jabir SM, Nurazilah MZ, Afiq NHM, Bakar M, Nizam AJM, Zahid OA, Bakri MHM (2016) Application of potassium carbonate as space holder for metal injection molding process of open pore copper foam. Proc Chem 19:552–557. https://doi.org/10.1016/j.proche.2016.03.052 CrossRefGoogle Scholar