Genetic Algorithm-Assisted Combinatorial Search for New Blue Phosphors in a (Ca,Sr,Ba,Mg,Eu)xByPzOδ System

Abstract

Genetic algorithm-assisted combinatorial chemistry (GACC) was implemented to search for new blue phosphors in seven cation systems, including CaO, MgO, BaO, SrO, B2O3, P2O5, and Eu2O3. The GACC process was followed by a series of fine-tuning processes based on conventional high-throughput screening employing quaternary and ternary libraries, to pinpoint promising compositions. GACC was found to be useful as a preliminary step for final screening. This series of processes involving computations and actual syntheses led us to (Sr1-x-yCaxBay)2P2O7:Eu2+ (0.32 < x < 0.72, y < 0.04) phosphors. It was found that the boron addition played a significant role in enhancing the luminance but it was completely evaporated during the synthesis, and an excessive amount of alkali earth elements was essential for better luminescence. The luminance of (Sr1-x-yCaxBay)2P2O7:Eu2+ (0.32 < x < 0.72, y < 0.04) phosphors reached 70% of a commercially available BAM phosphor at 254 nm excitation. The color chromaticity was in the deep blue region, x = 0.15, y = 0.05. The structure of these phosphors was found to be Sr2P2O7 (Pnma, 62), but the luminescent property was far better than the Sr2P2O7:Eu2+ phosphor.