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

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 Gd3+ -incorporated Ba3WO6:Mn4+ 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 2Eg.4A2g transition of activator Mn4+. It was observed that the luminescence of Ba3WO6:Mn4+ material was almost ignorable due to the low quantum yield (less than 2%). After the introduction of certain amount of Gd3+ ions to substitute the octahedral Ba2+ site, the double-perovskite structure of the phosphor was hardly changed, but the deep-red emission intensity of Mn4+ was efficiently enhanced and the quantum yield reached 30.4% through the optimization to the Gd3+ and Mn4+ doping concentration. The optimal composition was Ba2.1Gd0.9WO6:0.3% Mn4+ 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 Gd3+ 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.