Tuning the Mn⁴⁺Coordination Environment in Mg₂TiO₄through a Codoping Strategy for Enhancing Luminescence Performance

In the present work, a series of M n+ cations (including Ca 2+, Sr 2+, Ba 2+, Li +, Na +, or Al 3+ ) and Mn 4+ codoped Mg 2 TiO 4 samples were synthesized through the hydrothermal–calcination route with an aim to explore the crystal structure and luminescence performance in which M n+ acted as codoped ions. The sites of Mg 2+ or Ti 4+ were occupied by M n+, resulting in a variety of coordination environments around Mn 4+ ions. Through the methods of experimental characterization and theoretical simulation, the effect of codoping on the lattice structure, electronic structure, and photoluminescence properties was systematically investigated. The emission intensity of the Li/Mn codoped Mg 2 TiO 4 sample was much higher than that of other samples, which is believed to be related to structural symmetry, codoping effect, and its relevant defect chemistry. By crystal microstructure control and ion codoping, the luminescence properties of Mn 4+ must have been well regulated and optimized. The finding in this work is meaningful in the luminescence field, which may provide a strategy for developing novel photoluminescent materials.