Mn/Mn co-doped LaMAlO (M = Mg, Zn) luminescent materials: electronic structure, energy transfer and optical thermometric properties.

Dual-emitting manganese ion doped LaMAlO (M = Mg, Zn) phosphors were prepared by substituting Zn/Mg with Mn and replacing Al with Mn. The LaMAlO:xMn,yMn phosphors show a narrow green emission band of the Mn ions at 514 nm and a red emission band of the Mn ions at 677 nm. In addition, the thermal stability of luminescence shows that the response of Mn and Mn to the temperature is obviously different in LaMAlO, implying the potential of the prepared phosphors as optical thermometers. The decay lifetime of Mn was changed with temperature due to the different fluorescence intensity ratios of Mn and Mn, and a dual-mode optical temperature-sensing mechanism was studied in the temperature range of -50-200 °C. The maximum relative sensitivities (S) are calculated as 3.22 and 3.13% K, respectively. The unique optical thermometric features demonstrate the application potential of LaMAlO:Mn,Mn in optical thermometry.