Characterization of Superfine Sr_2 CeO_4 Powder Prepared by Microemulsion-Heating Method

摘要

Powder phosphor of Sr_2CeO_4 is prepared by microemulsion-heating method and a film of the phosphor on ITO glass is formed by electrophoretic deposition. Field emission scanning electron microscopy (FE-SEM) images show that the powder fired at 850 t for 4 h has a spherical shape with an average diameter of 70 ~ 80 nm whereas the powder sintered at 900 deg C for 4 h and 1000 t for 4 h have shuttle-like and spherical shapes, respectively, with both sizes less than 1 mu m. X-ray diffraction (XRD) patterns indicate that the superfine Sr_2CeO_4 exhibits an orthorhombic crystal structure. Room-temperature photoluminescence (PL) measurements show that there are three excitation peaks located at around 262, 280 and 341 nm, and all the Sr_2CeO_4 samples display an intense blue emission at 470 nm with CIE coordinate of (x, y) - (0.176, 0.283) . The quantum yield of phosphor is high up to 0.47 + - 0.04. Compared with Sr_2CeO_4 samples prepared with traditional high-temperature heating, the phosphor synthesized with this method has a smaller size, lower calcination temperature , and shorter calcination time, and the main excitation and emission bands are blue shifted about 30 and 12 nm respectively . The startup voltage for Sr_2CeO_4 film on ITO glass shifts from 2700 to 4000 V with increasing thickness of the film.