Electric field assisted diffusion and sintering of polycrystalline ceria

Topic

In this project we focus on the effect of electric fields on diffusion processes, grain boundary formation and resulting densification behaviour of doped und pure ceria. The nature (DC/AC) and amplitude of applied field, as well as the possibility of current flow leading to Joule heating will be systematically investigated.

More specifically, the following points are of interest:

• How are diffusion processes (surface, grain boundary and bulk) affected?
• Are grain boundaries and related space charge layers irreversibly modified (structure, chemistry, electrical properties)?
• What are the consequences on the sintering behaviour (especially sintering stress and viscous parameters) and microstructural evolution (neck and pore geometry)?

To answer these questions, the following methodology will be used:

• Diffusion profiles measured by ToF-SIMS will be compared with theoretical tracer distributions. Numerical simulations of space-charge layers at boundaries will be performed in the Poisson-Cahn framework (R. A. De Souza, RWTH Aachen)
• Advanced electron microscopical methods such as electron holography and in-situ testing at high temperature and confined atmosphere (R. Dunin-Borkowski, ER-C, Forschungszentrum Jülich)
• Loading dilatometry under electric stimuli and impedance spectroscopy, to be correlated with quantitative analysis of reconstructed sintered volumes and mesoscopic modelling (O. Guillon, IEK-1, Forschungszentrum Jülich).

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