Novel efficient deep-red emitting phosphor SrCaGaO:Mn with tululite-related structure.

Mn-activated phosphors have been attracted to replace the rare-earth-activated phosphors in the use of deep-red optical devices. Owing to their low toxicity and wide applications, oxide materials are promising hosts for Mn phosphors. Exploration into novel oxides is important for developing new Mn-doped phosphors with high luminescent efficiencies. In this study, we discovered the deep-red emitting phosphor SrCaGaO:Mn in the SrGaO-CaGaO solid solution system. From the single crystal X-ray diffraction analysis, SrCaGaO:Mn was found to crystallize in a cubic unit cell with space group 432. Furthermore, SrCaGaO:Mn was revealed to be a new member of tululite structure-related phosphors, such as CaZnAlO:Mn, CaZnGaO:Mn, and CaMgGaO:Mn. To study the fundamental luminescence properties, we synthesized SrCaGaO:Mn powder samples the conventional solid-state reaction method. SrCaGaO:Mn has an absorption band in the region of 250-550 nm, and shows a deep-red emission band peaks at 712 nm. The excitation band is well matched to the emission wavelength of near-ultraviolet and blue light emitting diodes. The optimized sample exhibited high quantum efficiency and good thermal quenching properties. This study revealed SrCaGaO:Mn has excellent potential as a deep-red emitting phosphor and is expected to be used for commercial applications, such as indoor plant cultivation and wavelength down-convertor for solar-cells.