Mn⁴⁺-doped rare-earth-free Mg₄Nb₂O₉ phosphors for optical temperature sensing

In this report, rare-earth-free Mg₄Nb₂O₉:Mn⁴⁺ phosphors were obtained through a high-temperature solid-state reaction. This work aims to investigate the photoluminescence properties of Mg₄Nb₂O₉:Mn⁴⁺ phosphors and the temperature sensitive performance of the optimized phosphor. The crystal structure and lattice parameters as well as the effects of the dopant ions on the host structure were investigated. It should be noted that the Mg₄Nb₂O₉ crystal is in a trigonal system P3̄c1. The as-prepared phosphors exhibited good thermal sensitivity, and the relative sensitivity of the optimal Mg₄Nb₂O₉:0.004Mn⁴⁺ phosphor was calculated to be 0.48% K^-1, allowing it to activate optical temperature sensing applications.