Color tunable Er-Eu co-doped double perovskite La₂MgSnO₆ phosphor for optical temperature sensor

To develop new luminescent materials for optical thermometers, a series of Er³⁺/Eu³⁺doped double perovskite La₂MgSnO₆ phosphors are synthesized by a high-temperature solid-phase method. The structure, luminescence performance, energy transfer, and thermal sensitivity are systematically studied by X-ray diffraction (XRD), scanning electron microscopy fluorescence spectroscopy, lifetime decay curve, and temperature-dependent emission spectra. The prepared samples possess good coincidence with pure perovskite phase, and the refined high-quality XRD data reveal that Eu³⁺ and Er³⁺jointly occupy La³⁺ sites. which is attributed to the effective energy transfer from Er³⁺ to Eu³⁺ ions. By adjusting the doping concentration of Eu³⁺, the emission of Er³⁺ is attenuated and the luminous color is modulated from green to orange-red. These demonstrate the existence of energy transfer between Er³⁺ and Eu³⁺. In addition, the optimized La₂MgSnO₆: 0.075Er³⁺, 0.04Eu³⁺ phosphor exhibits excellent thermal stability and good temperature cycling. The emission intensity showed good cycling in the process of repeated heating and cooling, and maintained to 76% of the initial temperature (303K) at 403K. Studied the optical temperature sensing performance of LMS: 0.075Er³⁺, 0.04Eu³⁺ fluorescent powder. The results of fitting the fluorescence intensity ratio with the non-thermal coupling characteristic peaks of 555 and 706nm showed excellent optical sensitivity, and the S_a and S_r were calculated as 0.0029K⁻¹ and 1.21%K⁻¹, respectively. All results indicate that LMS: 0.075Er³⁺, 0.04Eu³⁺ phosphors could have potential applications for non-contact optical temperature measurement materials.