The behaviour of ceramics at the nanometre scale may strongly differ from their bulk counterparts. Controlling plastic deformation of nanoparticles during ceramics processing might be a way to enhance their properties or to improve the processing route. However, the literature still lacks information regarding plasticity mechanisms in many oxides. In situ mechanical testing in Transmission Electron Microscopy (TEM) is a convenient technique to study plasticity in nano-objects as it provides force measurements associated with live video recording up to atomic resolution.

The experimental set-up and the procedure used for data processing will first be described. The technique will then be applied to cerium oxide (CeOx) nanocubes, with sizes in the range 20-130 nm. Experiments under different conditions (dose rate, environment gas pressure) will be shown. The values measured for the Young modulus on single nanocubes under different conditions will be compared with theoretical values and discussed. The plasticity mechanism will also be determined and compared with simulation results. Moreover, as CeOx undergoes a reversible effect of the electron dose on the nanocube crystallographic phase and composition, the effect of the electron dose rate on the nanocube mechanical behaviour will be explored. We will show the evolution of the yield stress and the appearance of stacking faults. Finally, the effect on the nanocube size on the yield stress will be investigated and discussed in the light of the plasticity mechanism.