Preparation and structural investigations of sol-gel derived Eu3+-doped CaAl2O4

Monoclinic and hexagonal undoped and Eu3+-doped calcium aluminates (CaAl2O4) were prepared as powders using sol-gel methodology after thermal treatments at 850∘C (hexagonal form) or 1200∘C (monoclinic form). Attempt was made to solve the unknown structure of the metastable hexagonal form by synchrotron powder diffraction in an average P63 model. The structural features of the metastable phase were investigated using infrared and Raman spectroscopies and by studying the luminescence properties of the Eu3+doped phases.