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Materials (Basel). 2019 Apr 14;12(8). pii: E1218. doi: 10.3390/ma12081218.

Gd/Sm-Pr Co-Doped Ceria: A First Report of the Precipitation Method Effect on Flash Sintering.

Author information

1
Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino (FR), Italy. l.spiridigliozzi@unicas.it.
2
Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy. lorenzo.pinter@alumni.unitn.it.
3
Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy. mattia.biesuz@unitn.it.
4
Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via G. Di Biasio 43, 03043 Cassino (FR), Italy. gianfranco.dellagli@unicas.it.
5
Center of Hydrogen-Fuel Cell Research, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu, Seoul 136-791, Korea. d16605@kist.re.kr.
6
Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy. vincenzo.sglavo@unitn.it.

Abstract

In this work, ceria-based ceramics with the composition Gd0.14Pr0.06Ce0.8O2-δ and Sm0.14Pr0.06Ce0.8O2-δ, were synthesized by a simple co-precipitation process using either ammonium carbonate or ammonia solution as a precipitating agent. After the calcination, all of the produced samples were constituted by fluorite-structured ceria only, thus showing that both dopant and co-dopant cations were dissolved in the fluorite lattice. The ceria-based nanopowders were uniaxially compacted and consequently flash-sintered using different electrical cycles (including current-ramps). Different results were obtained as a function of both the adopted precipitating agent and the applied electrical cycle. In particular, highly densified products were obtained using current-ramps instead of "traditional" flash treatments (with the power source switching from voltage to current control at the flash event). Moreover, the powders that were synthesized using ammonia solution exhibited a low tendency to hotspot formation, whereas the materials obtained using carbonates as the precipitating agent were highly inhomogeneous. This points out for the first time the unexpected relevance of the precipitating agent (and of the powder shape/degree of agglomeration) for the flash sintering behavior.

KEYWORDS:

co-doped ceria; flash sintering; precipitation

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