Synthesis and luminescence properties of deep-red emitting Mn4+ doped α-Al2O3 for professional LED grow light

Abstract

Red-emitting α-Al2O3:Mn4+ fluorescent powders were prepared by co-precipitation method and sintered at1000 to 1500oC in the air. Effects of sintering temperature and Mn4+ concentration on the optical properties of the materials were investigated. The X-ray diffraction (XRD) showed that the crystallinity of Al2O3 belonged to hexagonal with R3C space group. The excitation spectrum consisted of two broad intense bands centered at 399 and 568 nm and was assigned to 4A2g(F)→4T1g(F) and 4A2g(F)→4T2g(F) transitions, respectively. Under the excitation wavelengths of 399 and 568 nm, the α-Al2O3:0.1% Mn4+ phosphors emitted efficient red light at 694 nm caused by 2Eg→4A2g transition. A red LED is made by coating Al2O3:0.1% Mn4+ powder on a violet chip located in the deep-red light region. These results showed that α-Al2O3:Mn4+has the potential to produce red LED lightings for plants.