Speaker
Description
Cerium oxide is widely used in many applications, such as in solid oxide fuel cell electrodes, catalysis, or gas detection. There are, nevertheless, few experimental evidences to show the evolution of defects in this structure which may have a significant impact on many properties, especially on mechanical behavior.
In situ nanocompression experiment in a transmission electron microscope is a dedicated experiment to observe and follow the evolution of defects. This technique has been considered to test cerium oxides nanocubes (20-50nm size), using a Hysitron PI 95 sample holder in an environmental transmission electron microscope (ETEM).
Depending on the oxygen content and illumination conditions, cerium oxide nanocubes present different cubic structures: either a fluorite one (space group Fm-3m) or a bixbyite one (space group Ia-3). For both space groups, plasticity is evidenced at room temperature. High resolution imaging performed during compression allows the monitoring of dislocation, stacking fault and nano-twin formation. We will discuss the different possible mechanisms to explain the plasticity observed experimentally in the light of the literature found on other fluorite structures and Molecular Dynamics simulations. The effect of the electron beam will also be discussed.
| Speaker Country | France |
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