Morphology and luminescence of MgAl2O4 ceramics obtained via spark plasma sintering

Spark plasma sintering cycles were applied to a commercial magnesium aluminate spinel powder to evaluate its suitability for producing small-grained optical ceramics. Translucent stoichiometric samples with a crystalline grain size as small as similar to 0.5 mu m were obtained. Structural, microstructural (XRD and SEM), and correlated spectroscopic (transmission and cathodoluminescence) analyses were used to further investigate the defect structure and inversion degree of the material. We argue that the transparency is closely related to F and F+ centers, which can be distinguished in the absorption and luminescence spectra of the stoichiometric compositions.