Mn⁴⁺-Activated Double-Perovskite-Type Sr₂LuNbO₆ Multifunctional Phosphor for Optical Probing and Lighting

Multifunctional phosphors have significant application and scientific value and are becoming a research hotspot in the field of luminescent materials. Herein, we report Mn⁴⁺-activated double-perovskite-type Sr₂LuNbO₆ multifunctional phosphors with excellent comprehensive properties in the fields of optical temperature/pressure sensing and w-LED lighting. The crystalline structure, elemental composition, optimal doping concentration, crystal-field strength, and optical bandgap of the phosphors are investigated in detail, and the mechanisms of concentration and thermal quenching are discussed. From the optimal Sr₂LuNb_0.998O₆:0.2%Mn⁴⁺ phosphor, a LED lamp for indoor warm-white lighting is successfully fabricated. Further, the thermometric properties of the phosphors are explored for applications as FIR- and lifetime-based thermometers, showing a maximum relative sensitivity of 1.55% K^-1 at 519 K. Upon pressure loading, a significant red-shift of the peak centroid is observed, and the pressure sensitivity is determined to be 0.82 nm/GPa. These results suggest that the Mn⁴⁺-activated Sr₂LuNbO₆ multifunctional phosphors have great potential to be utilized in the fields of optical thermometry, manometry, and lighting.