Abstract
Mn(4+)-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(4+) phosphors. Exploration into novel oxides is important for developing new Mn(4+)-doped phosphors with high luminescent efficiencies. In this study, we discovered the deep-red emitting phosphor SrCa(2)Ga(2)O(6):Mn(4+) in the Sr(3)Ga(2)O(6)-Ca(3)Ga(2)O(6) solid solution system. From the single crystal X-ray diffraction analysis, SrCa(2)Ga(2)O(6):Mn(4+) was found to crystallize in a cubic unit cell with space group F432. Furthermore, SrCa(2)Ga(2)O(6):Mn(4+) was revealed to be a new member of tululite structure-related phosphors, such as Ca(14)Zn(6)Al(10)O(35):Mn(4+), Ca(14)Zn(6)Ga(10)O(35):Mn(4+), and Ca(14)Mg(4)Ga(12)O(36):Mn(4+). To study the fundamental luminescence properties, we synthesized SrCa(2)Ga(2)O(6):Mn(4+) powder samples via the conventional solid-state reaction method. SrCa(2)Ga(2)O(6):Mn(4+) 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 SrCa(2)Ga(2)O(6):Mn(4+) 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.