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 Ca²⁺.