Electron microscopy study of pure and doped synthetically grown CaF2 crystals

An electron microscopy study of CaF2 crystals, pure or doped with either uranium or thorium, is performed. The electron diffraction patterns show several extra spots attributed to the CaF2 lattice deformation. The deformation is determined by the presence of colloidal particles, formed as a result of electron-irradiation-induced defect aggregation. On a etudie par microscopie electronique des cristaux de CaF2, pures ou doppes avec uranium ou thorium. Les images de diffraction electronique montrent plusieurs touches supplementaires attribues a la deformation du reseau CaF2. La deformation est determinee par la presence des particules colloidales, formees par l'aggregation de defauts produites par irradiation electronique.