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Field assisted sintering of rare earth doped ceria

Densification and Coarsening

Field assisted sintering of rare earth doped ceria

Univ.-Prof. Dr.-Ing. Christoph Broeckmann
RWTH Aachen University

Augustinerbach 4
52062 Aachen
Telefon: 0241 / 80 94321
Fax: 0241 / 80 92266

PD Dr. Martin Bram
Forschungszentrum Jülich GmbH
Institute of Energy and Climate Research
IEK-1: Materials Synthesis and Processing (IEK-1)

52425 Jülich
Telefon: 02461 / 61 6858
Fax: 02461 / 61 2455

Proj.-Nr. BR 1844/21-1Proj.-Nr. BR 3418/1-1

Due to its mixed ionic and electronic conductivity (MIEC), rare earth doped ceria (REDC) represents a promising class of materials for electrochemical devices like solid oxide fuel cells (SOFCs) or solid oxide electrolysis cells (SOECs). To tailor the electrochemical properties of REDC, exact control of material synthesis and processing conditions is strictly required.

The field assisted sintering technology/spark plasma sintering (FAST/SPS) is an innovative technology, which offers the potential to tailor the microstructure and final properties of REDC. Furthermore, it is an economical process since the energy demand and duration of the sintering cycle can be significantly reduced compared to conventional sintering. Amongst others, the electronic conductivity makes REDC a promising candidate for successful application of FAST/SPS due to the direct heating of the ceramic by the Joule effect. Up to now, less information can be found in literature on FAST/SPS of REDC, which – to our knowledge – is caused by the fact that the material tends to severe crack formation, if processed under standard FAST/SPS conditions using graphite dies and Argon atmosphere. To overcome this restriction, our research concept deals with the following challenges:

i.Atmosphere control in the FAST/SPS device
ii.Control of the heating and – much more important – cooling rates during the FAST/SPS cycle
iii.Control of the electrical current with regard to the temperature dependent semi conduction of REDC
iv.Understanding and control of the chemical interaction between REDC and the tool material
v.Numerical simulation to reduce the experimental effort and to deepen the general understanding of sintering of MIEC ceramics activated by an electric field