Long lasting phosphorescence behavior of Pr3+-doped CaTiO3-based oxides

Ceramic samples with nominal compositions of (Ca1−xSrx)0.9Pr0.001Zn0.099TiO3 (x = 0, 0.05, 0.10, 0.15, 0.20) were prepared by a mixed oxide method. When examined by the X-ray diffraction (XRD) analysis, the samples revealed a main CaTiO3 phase with small amounts of a second Zn2TiO4 phase. All of the ceramic samples emitted red phosphorescent light at about 613 nm when excited by light of a wide wavelength range (200 nm to about 500 nm). The partial substitution of Sr for Ca, up to approximately 10 at%, significantly enhanced the phosphorescence intensity and lifetime. The long lasting phosphorescence could be observed with naked eyes in dark room for more than 10 min in both air and water at room temperature.