Study on the red/far-red emitting Mn4+ doped Y3Al5O12-YAlO3 phosphors for plant growth lighting

Abstract

Mn⁴⁺-doped Y₃Al₅O₁₂-YAlO₃ phosphors (YAG-YAP:Mn⁴⁺) were successfully fabricated by a solid-state reaction method supported by a high-energy planetary ball milling. X-ray diffraction pattern (XRD) analysis result shows that the obtained product consists of two main Y₃Al₅O₁₂ (YAP) and YAlO₃ (YAG) phases when the sample is annealed at higher temperatures of 1300°C. Field emission scanning electron microscopy (FESEM) and X-ray energy dispersion spectrum (EDS) spectra indicate that the high-purity YAG-YAP:Mn⁴⁺ phosphors have a granular form with an average size of about 1-5 µm. By photoluminescence excitation (PLE) and photoluminescence spectra investigation, the YAG-YAP: Mn⁴⁺ phosphors, which could be well excited at two wavelengths of 305 and 477 nm, emit strongly in a wide wavelength range from the red light region (674 nm) to the far red region (715 nm). The 674 and 715 nm peaks are attributed to the ²E^___>⁴A₂ transition of Mn⁴⁺ ions in the YAG and YAP lattices, respectively. Under the experimental conditions, the highest photoluminescence intensity is found in the YAG-YAP:0.2%Mn⁴⁺ sample after annealing at 1300°C for 5 hours in the air. Compared with the far-red phytochrome absorption spectrum of plants, the photoluminescence spectrum matching rate of the YAG-YAP:Mn⁴⁺ sample is up to 36.1%. The obtained results suggest that the synthesised YAG-YAP:Mn⁴⁺ phosphors have great potential for application in specialised plant growth LED.