2.6. Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-Ray Spectroscopy (EDX)

MgF₂ particles were prepared by adding 20 µL of 1 M MgCl₂ to 10 µL of 1 M NaF. The sample was incubated at 37 °C for 30 min. 3 µL of the sample was then left to dry for 15 h on a glass slip. The dried sample was subjected to platinum sputtering for 45 s at a current of 30 mA, and a tooling factor of 2.3. The particles were visualised at 10 kV (for EDX) and 5 kV (for SEM). The device used was Hitachi/SU8010 (Tokyo, Japan).