Point Defects in Magnesium Aluminates Spinel Ceramics Doped with Lithium Fluoride

The nature and topological distribution of optical centers within various regions of hot pressed disks of transparent magnesium aluminates spinel ceramics doped with LiF were studied. In the optical absorption spectra of this type of ceramic, bands were revealed at 4.75 eV and 5.3 eV, which were identified with $F^{+}-$ and F-centers, respectively. Because both bands are formed by anionic vacancies which captured one or two electrons, the topological distribution of anionic vacancies was determined. The band at 5.65 eV was also found which is tentatively identified with complex centers of anionic vacancies that capture fluorine ions and electrons. Using X-ray irradiation the variety of absorption bands of hole centers related to cationic vacancies was established. The spatial distribution of cationic vacancies within the ceramic disk was also determined.