Microstructure Characterization of La-Ca-Sr-Mn-O Magnetocaloric Ceramics Prepared by Spark Plasma Sintering Method

Abstract:

The influence of different sintering temperatures during Spark Plasma Sintering (SPS) process on microstructure of La-Ca-Sr-Mn-O ceramics has been studied. The powders of La_0.67Ca_0.33-xSr_xMnO₃ (x = 0.33; 0.03) (LCSM) perovskite were prepared by milling of the stoichiometric amounts of the starting materials - lanthanum oxide (La₂O₃), calcium oxide (CaO), strontium carbonate (SrCO₃) and manganese oxide (MnO₂), and subsequently calcinated twice. After the second calcinations the LCSM powders were treated by SPS method at four different temperatures (1000°C, 1150°C, 1200°C and 1250°C), at uniaxial pressure of 50 MPa in a vacuum. The microstructure characterizations were done by polarized light microscopy and scanning electron microscopy. The microstructural observations showed that increasing sintering temperature leads to an increase of grain size. The energy dispersive spectral (EDS) analysis confirmed that higher sintering temperatures cause changes in the phase composition of the investigated LCSM perovskite materials. The benefits of the LCSM samples preparation by SPS process are discussed.

• Periodical: Materials Science Forum (Volume 891)
• Pages: 468-472
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.891.468
• Online since: March 2017
• Authors: Katarina Zmorayova, Pavel Diko, Jacques G. Noudem
• Keywords: La-Ca-Sr-Mn-O Perovskite, Magnetocaloric Ceramics Material, Microstructure, Spark Plasma Sintering, Thermal Analyses

References

[1] K.A. Gschneidner Jr, V.K. Pecharsky, A.O. Tsokol, Recent developments in magnetocaloric materials, Rep. Prog. Phys. 68 (2005) 1479–1539.

DOI: 10.1088/0034-4885/68/6/r04

[2] N. Pryds, F. Clemens, M. Menon, P. H. Nielsen, K. Brodersen, R. Bjork, Ch. R. H. Bahl, K. Engelbrecht, K. K. Nielsen, A. Smith, A Monolithic Perovskite Structure for Use as a Magnetic Regenerator, J. Am. Ceram. Soc. 94. 8 (2011) 2549–2555.

DOI: 10.1111/j.1551-2916.2011.04398.x

[3] K. Zmorayova, S. Piovarci, M. Radusovska, V. Antal, V. Kavecansky and P. Diko, Materials Science Forum 782 (2014) 503-506.

DOI: 10.4028/www.scientific.net/msf.782.503

[4] O. Guillon, J. G. -Julian, B. Dargatz, T. Kessel, G. Schierning, J. Rathel and M. Herrmann, Field-Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments, Advanced Engineering Materials 16. 7 (2014).

DOI: 10.1002/adem.201300409