Synthesis and up-conversion luminescence properties of Er3+/Yb3+ co-doped Sr2CeO4 phosphors

Er3+/Yb3+ co-doped Sr2CeO4 phosphors were synthesized using a high-energy ball milling method at 1100 °C. The X-ray diffraction patterns confirmed their orthorhombic structure. The up-conversion emissions corresponding to 2H11/2→4I15/2, S3/2→4I15/2 and 4F9/2→4I15/2 transitions peaking at 526 nm, 552 nm and 669 nm have been observed under 975 nm excitation. With the help of a schematic energy level diagram the up-conversion mechanisms were discussed in detail. The excited state absorption and energy transfer process were discussed as possible up-conversion mechanisms. The energy back transfer (4S3/2+2F7/2→4I13/2+2F5/2) contribute the increased intensity ratio of red to green emission in Sr2CeO4:Er3+/Yb3+ samples. A decay curve analysis for the UC emission corresponding to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions in the Er3+/Yb3+ co-doped Sr2CeO4 phosphors was performed. The CIE chromaticity coordinates of the Er3+/Yb3+ co-doped Sr2CeO4 phosphors were located in the green region. The results indicate that the material may be suitable for applications in the fields of color displays and light emitting devices.