Synergistic luminescent thermometer and indoor plant growth lighting utilizing the Mg2LaSbO6:Eu3+/Mn4+ phosphor

Abstract

The development of non-contact temperature sensors has attracted much attention, and high sensitivity is the difficulty to overcome. A new type of red phosphor, Mg₂LaSbO₆:Eu³⁺,Mn⁴⁺ (MLSO:Eu³⁺,Mn⁴⁺), was synthesized by the solid phase reaction method. The effect of different Eu³⁺ concentrations on its luminescence was discussed, and its temperature-sensitive properties were studied. The results indicate that Eu³⁺ and Mn⁴⁺ successfully entered the matrix lattice, causing slight distortion of the crystal structure of the phosphor MLSO:Eu³⁺,Mn⁴⁺. The emission spectrum of the phosphor MLSO:Eu³⁺,Mn⁴⁺ consists of sharp emission peaks of Eu³⁺ (560–640 nm) and broadband emission peaks of Mn⁴⁺ (640–800 nm). The experimental results show that the red light emission (612 nm) intensity of Eu³⁺ and the deep red light emission (695 nm) intensity of Mn⁴⁺ in the phosphor MLSO:Eu³⁺,Mn⁴⁺ are temperature dependent. Therefore, using the Fluorescence Intensity Ratio (FIR) technique, temperature fluorescence testing was conducted on the phosphor MLSO:0.02Eu³⁺,0.002Mn⁴⁺ to achieve visible light temperature measurement. The maximum relative sensitivity (S_r) was calculated to be 3.97% K⁻¹ (@440 K), and the maximum sensitivity (S_a) was 0.17 K⁻¹ (@400 K). Meanwhile, the electroluminescence spectra of LED devices prepared using the phosphor MLSO:0.06Eu³⁺,0.002Mn⁴⁺ were consistent with the absorption spectra of chlorophyll (A and B) and photosensitizers (Pr and Pfr) required for plant growth. It shows that the phosphor MLSO:Eu³⁺,Mn⁴⁺ can be used in the field of optical temperature measurement and indoor plant growth lighting.