Far-red emitting MgAl2O4:Cr3+ceramic phosphors with luminescence thermal stability for plant lighting LEDs

MgAl 2 O 4 :Cr 3+ far-red emitting ceramic phosphors were prepared by the solid-state reaction method. The photoluminescence characteristics, especially the luminescence thermal stability, thermal conductivity, and its application in phosphor-converted LEDs were studied. Under 450 nm excitation, the ceramic phosphors exhibited an emission range of 650-750 nm and showed a narrow-band emission peaked at 688 nm. It also shows 708 nm and 718 nm far-red emission, which matches well with the absorption peak of the plant phytochrome P FR . The luminescence thermal stability of MgAl 1.99 O 4 :0.01Cr 3+ was excellent. The integral intensity of the two emissions peaked at 708 nm and 718 nm at 500 K can maintain 98.27% and 98.24% of the counterparts measured at room temperature, respectively, showing zero thermal quenching behavior up to 500 K. The thermal conductivity of the MgAl 1.99 O 4 :0.01Cr 3+ ceramic was 10.3 W·m -1 ·K -1 . These results indicate that MgAl 2 O 4 :Cr 3+ ceramic phosphors can be applied in plant lighting when packaged onto 450 nm blue LED chips.