Efficiently enhanced deep-red emission of Ba3WO6:Mn4+ oxide phosphor via the Gd3+ incorporation

Abstract

At present, it is highly desirable to seek the inorganic phosphors with deep-red emission for the plant cultivation lighting. In this paper, the lanthanide Gd 3+ -incorporated Ba 3 WO 6 :Mn 4+ oxide phosphors were successfully prepared by the conventional high-temperature solid state reaction. The oxide phosphors were confirmed to crystallize into the double-perovskite structure corresponding to the cubic system with space group Fm-3m. Under the excitation with ultraviolet light 365 nm, all the phosphor samples displayed the deep-red emission band from 650 to 750 nm with the peaks around 678 and 692 nm, which was attributed to the intrinsic 2 E g → 4 A 2g transition of activator Mn 4+ . It was observed that the luminescence of Ba 3 WO 6 :Mn 4+ material was almost ignorable due to the low quantum yield (less than 2%). After the introduction of certain amount of Gd 3+ ions to substitute the octahedral Ba 2+ site, the double-perovskite structure of the phosphor was hardly changed, but the deep-red emission intensity of Mn 4+ was efficiently enhanced and the quantum yield reached 30.4% through the optimization to the Gd 3+ and Mn 4+ doping concentration. The optimal composition was Ba 2.1 Gd 0.9 WO 6 :0.3%Mn 4+ and the Commission International de L'Eclairage (CIE) color coordinate was (0.731, 0.269), which located at the deep-red spectral region. The mechanism for the enhanced deep-red luminescence after Gd 3+ incorporation was discussed. Owing to the highly suited to the phytochrome absorption wavelength, the optimized oxide phosphor with bright deep-red emission in the 650–750 nm range is a potential candidate for the plant cultivation lighting.