Luminescence optimization of MBO3:Eu3+ (M=Y, Gd, Al) red phosphor by spray pyrolysis using combinatorial chemistry

Conventional solution-based combinatorial chemistry was combined with spray pyrolysis and applied to optimize the luminescence properties of (Yx, Gdy, Alz)BO3:Eu3+ red phosphor under vacuum ultraviolet (VUV) excitation. For the Y–Gd–Al ternary system, a compositional library was established to seek the optimal composition at which the highest luminescence under VUV (147 nm) excitation could be achieved. The Al content was found to mainly control the relative peak ratio (R/O) of red and orange colors due to the 5D0→7F2 to 5D0→7F1 transitions of Eu3+. The substitution of Gd atoms in the place of Y sites did not contribute to change the R/O ratio, but was helpful to enhance the emission intensity. As a result, the 613 nm emission peak due to the 5D0→7F2 transitions of Eu3+ was intensified by increasing the Al/Gd ratio at a fixed Y content, resulting in the improvement of the color coordinate. Finally, the optimized host composition was (Y0.11, Gd0.10, Al0.79)BO3 in terms of the emission intensity at 613 nm and the color coordinate.