Cathodoluminescence, SEM and EDX analysis of CaF2 and Tm2O3 pellets for radiation dosimetry applications

Highlights: • A simple dry thermal process was performed to activate CaF₂ with Tm₂O₃ (3 mol%). • EDX spectra and composition maps showed the average homogeneity of the specimens. • SEM/CL-RGB images displayed a new LC in the blue wavelength (450–475 nm) due to the material fabrication process. Preparation and synthesis of luminescent materials has a special interest in medicine, industry and research due to the wide variety of applications offered by phosphors. In this study, pellets of a mixture of CaF₂ and Tm₂O₃ which were pressed and thermally treated up to 600 °C were prepared in air. Combined SEM (scanning electron microscopy), EDX (energy dispersive X-ray analysis) and CL-RGB (cathodoluminescence red-green-blue) microanalysis and, complementarily spectral CL analysis of this phosphor were performed. EDX analysis showed that the activator was homogeneously distributed in the prepared specimens. The additional CL emission can be attributed to the properties of some luminescent centers that were apparently created during the annealing. In addition, it seems that other trapping centers were created by new structural defects during the preparation process in the CaF₂ lattice. The combined techniques SEM/EDX/CL-RGB have confirmed their capabilities in the characterization of the prepared materials. This contribution provides a process and characterization methods used in the fabrication and characterization of a phosphor that can also be used to optimize the luminescent emission of other similar synthetic materials with rare earth oxides as activators.