Photoluminescence performance of Er/Yb co-doped NBT ceramics prepared via hydrothermal method

Er/Yb co-doped Na0.5Bi0.5TiO3 (Na0.5Bi0.5-x-yErxYbyTiO3, NBT-Er/Yb) ceramics were prepared via a hydrothermal method, in which the effects of different content of Er/Yb co-doping on the NBT ceramics were studied. XRD and SEM analysis proved that the hydrothermal synthesized NBT-Er/Yb precursor powders present rather pure rhombohedral perovskite structure and homogeneous cube-shape particles with slight distortion composed of nano-sized lamellars. Pure rhombohedral perovskite structure NBT-Er/Yb ceramics accompanied by high densification and homogenous microstructure morphology were synthesized using the high active nano-sized particles, where slight impurity appears when the Yb doping content is larger than 7 mol%. The NBT-Er/Yb ceramics present the strongest emission peak at 550 nm under the excitation of 488 nm light, corresponding to the 4S3/2 → 4I15/2 electron transition, where the fluorescence intensity decreases rapidly with further increasing the Yb3+ doping content. Enhanced upconversion luminescence is induced by the Yb co-doping and the maximum intensity appears around 3-5 mol% Yb content in the NBT-Er/Yb ceramics under 800 nm light excitation, which emits strong yellowish green light centering around 542 nm, correlating with the electron transition from 4S3/2 to 4I15/2.