Update of the HTSI method: Application to the characterization of mechanical properties of CaF$$_2$$ from RT to $${800}\,^\circ \text{C}$$

The High-Temperature Scanning Indentation (HTSI) method (Tiphéne et al. in J Mater Res 36(12):2383–2396, 2021) allows for the characterization of material mechanical properties quasi-continuously over a large temperature range in 1-day experiments, based on a cycle with a constant maximum load applied regardless of the temperature. For materials exhibiting an Indentation Size Effect (ISE), the variations in hardness with temperature can stem from both temperature and ISE. It is challenging to differentiate their impact on the mechanical properties. So, a new 1-second indentation cycle was implemented, with an adjustment of the applied maximum load to control the maximum achieved depth across temperatures. It allows for the determination of mechanical properties at a given maximum depth over a wide temperature range. This methodology has been applied to CaF $$_2$$ single crystal from RT to $${800}\,^\circ \text{C}$$ . It enables the characterization of this material at $${1000}\,\text{nm}$$ depth over the entire temperature range. The obtained results are consistent with conventional indentation results.