Ti-doped MgAl2O4 spinel single crystals grown by the micro-pulling-down method for laser application: Growth and strong visible blue emission

The photoluminescence spectra of the rod-shaped pure and Ti-doped MgAl2O4 single crystals, grown by the micro-pulling-down (μ-PD) method, have been systematically investigated under high-intensity pulsed Nd3+: YAG laser excitation in the ultraviolet (UV) region (266 nm). The chemical properties of the grown crystals under reducing argon atmosphere will be reported and the annealing effect under oxidizing atmosphere will be discussed. The room temperature luminescence properties of Ti-doped MgAl2O4 single crystals were performed before and after annealing as a function of the titanium concentration. Three broad bands absorption in the UV/VIS (visible) spectral regions and a broadband visible blue emission were observed from Ti-doped MgAl2O4. An estimation of the decay time value of theses emissions was determined from the time-resolved spectra and the energies of the vibrational modes of the MgAl2O4 crystal are obtained from the infrared spectra.