Photoluminescence and electron paramagnetic resonance studies of Mn2+doped CaAl4O7

Manganese doped polycrystalline CaAl4O7 samples with doping concentrations in 0.1-2.0 mol% range were synthesized using the solid-state synthesis method. Photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopy techniques were applied to characterize the local structure and properties of Mn ions in CaAl4O7. With excitation of 406 nm, Mn2+ exhibited a wide emission band centered at 572 nm with luminescence decay time 6.5-8.3 ms. The results of EPR and X-ray diffraction (XRD) analyses evidenced preferential incorporation of Mn2+ in the seven-fold coordinated site of Cav.