Enhanced photoluminescence of the Ca0.8 Zn0.2 TiO3 :0.05% Pr3+ phosphor by optimized hydrothermal conditions.

The red-emitting phosphor Ca0.8 Zn0.2 TiO3 :Pr3+ was synthesized using an ethylene glycol (EG)-assisted hydrothermal method. The effects of additional amounts of and order of adding EG, plus hydrothermal temperature, time, and pH on the composition, morphology and optical properties of the titanate phosphors were studied. The crystalline phases of the titanate phosphors were confirmed to be constituted of a series of co-existing CaTiO3 , Zn2 TiO4 and Ca2 Zn4 Ti16 O38 compounds in various proportions that were visualized using an X-ray diffractometer (XRD). The optical properties of the phosphors were studied using photoluminescence spectra and UV-visible spectroscopy. The results show that the impurities Zn2 TiO4 :Pr3+ and Ca2 Zn4 Ti16 O38 :Pr3+ significantly contributed to the enhancement of an absorption band around 380 nm. The optimum Ca0.8 Zn0.2 TiO3 :Pr3+ phosphor consisting of appropriate amounts of CaTiO3 , Ca2 Zn4 Ti16 O38 and Zn2 TiO4 in three phases was achieved by controlling the hydrothermal conditions, and the obtained red phosphor exhibited the highest red emission (1 D2  → 3 H4 transition of Pr3+ ) with an ideal chromaticity coordinate located at (x = 0.667, y = 0.332) under 380 nm excitation.