The behavior of materials at the nanoscale is known to be different from the one observed for bulk material. Due to the nanometer size of the sample, it is nevertheless difficult to observe the mechanisms responsible for these differences, and to measure the differences of properties. This project will develop techniques to improve the accuracy when measuring the mechanical properties of nanoparticles.

It will consist in crossing and linking the results obtained by different techniques (in situ compression inside a transmission electron microscope (TEM) and Brillouin spectroscopy performed under pressure) to better identify the different sources of error inherent to these experimental techniques. Numerical simulations techniques will be developed in parallel to get reference data for the mechanical properties of nanoparticles.

In this project each technique will be further developed to measure properly the mechanical properties of individual nanoparticles. The influence of several parameters will be studied and the deviation with respect to reference data will be quantified. A real coupling of experimental devices will then be performed by adapting the TEM sample holder on a Brillouin spectrometer, so that both techniques can be used to measure the mechanical properties of the same nanoparticle. The comparison will be used to estimate error bars for each technique.

This project will be focused on CeO₂ nanocubes. CeO₂ is used in different applications like for instance catalytic systems, photocatalysis, or for biomedical applications. For all these applications, CeO₂ may undergo stresses leading to a change of its mechanical properties and then a loss of efficiency. The methodology developed in this project can then be used for all kinds of nanoparticles, whether they are metallic or ceramic. In particular, investigating the mechanical behavior of ceramics at the nanoscale can have a large impact on their processing route.