Thermally stable Cr3+-activated silicate phosphors for plant-growth LEDs and three-mode optical thermometry

The structural, optical and temperature-dependent luminescence properties of Y2Mg2Al2Si2O12:Cr3+ phosphors are investigated for their multifunctional applications. The as-prepared phosphors exhibited an intense far-red emission band around 600-850 nm with a peak at 687 nm, which matches well with the absorption band of plant phytochromes. Importantly, the optimized sample showed excellent thermal stability and the emission intensity at 423 K maintained about 77% of that at 298 K. The potential application of the phosphor in plant growth LED devices was also demonstrated. Furthermore, due to the unique thermal quenching behavior of Cr3+, a three-mode luminescent thermometry was designed based on the fluorescent intensity (FL), fluorescent intensity ratio (FIR), and full width at half maximum (FWHM) method. The maximum temperature relative sensitivity (Sr) of each mode can reach 2.74% K−1, 1.09% K−1, 1.47% K−1, respectively. These results indicate that the Y2Mg2Al2Si2O12:Cr3+ phosphors can address applications in plant growth and optical thermometry.