Li-doping effect on the photoluminescence behavior of CaTiO₃: Pr^(3+) nanopowder phosphors

Abstract

A red emission from Pr^(3+)-doped perovskite titanate is from the ^(1)D_(2) → ^(3)H_(4) transition of Pr^(3+). The improved luminescence properties by Li-adding to Pr^(3+)-doped CaTiO_(3). The properties of CaTiO_(3):Pr^(3+) and Li-added CaTiO_(3):Pr^(3+) powder have been investigated. The emissions of intra-4f transitions from the excited states (^(1)D_(2)) to the ground state (^(3)H_(4)) of Pr^(3+) are mainly observed around from 612 to 617 nm. The crystallinity, surface morphology and PL intensity of CaTiO_(3):Pr^(3+) powders have been improved by Li-adding. Among the powders with the different sintering temperature, Li-added CaTiO_(3):Pr^(3+) powder sintered at 800℃ showed the best luminescence brightness. Li-adding to the host lattice improved not only the crystallinity and but also the luminescent properties of CaTiO_(3):Pr^(3+) powders. The grain-size of Li-added CaTiO_(3):Pr^(3+) powder was larger than that of CaTiO_(3):Pr^(3+) powder. According to the results of photoluminescence (PL), the red emission peaks are attributed to ^(1)D_(2) → ^(3)H_(4) transition. The red emission peaks at 612 nm are assigned to 4f-5d transition from the ^(1)D_(2) states. The CaTiO_(3):Pr^(3+) nanopowders sintered at 900 oC shows a stronger PL intensity than another poders sintered different temperature. And Li-added CaTiO_(3):Pr^(3+) powders sintered at 800 oC shows the highest red emission. The intensity of the red emission radiated from the ^(1)D_(2) → ^(3)H_(4) transition was increased by more than 4.5 times by Li-adding. It is attributed that the Li+ ion plays a key role in order to make a good morphology and to have a good particle size distribution that is required to obtain the brightest phosphor. Thus, the red-emitting of Li-added CaTiO_(3):Pr^(3+) phosphor can give a promise for flat panel display (FPD) application.