Up-conversion photoluminescence based on the intrinsic defects in Na0.5Bi0.5TiO3:Yb3+ ceramics

•The UC PLis found basing on the intrinsic defects in the Na0.5Bi0.5TiO3:Yb3+.•The UC PL mechanism of the intrinsic defects was proposed.•The influencing factors on the UC PL were studied.•The PL properties of intrinsic defects can be tuned by the electric field.

Na0.5Bi0.5-xYbxTiO3 (NBT:xYb, x = 0-0.03) ceramics with different Yb doping contents were prepared with a conventional solid-state reaction method. A strong up-conversion photoluminescence (UC PL) based on the intrinsic defect of Na0.5Bi0.5TiO3:Yb3+ ceramics without doping any rare earth activators under a 980 nm diode laser excitation is found. The effects of annealing, temperatures, and external electric fields on the UC PL were investigated. It is found that the UC emissions can be tuned by both chemical method: annealing at 600 °C under a low oxygen pressure, and physical approach: an application of external electric field upon the ceramics. The possible UC PL mechanism of the defects in the ceramics is also discussed via the UC and down-conversion PL characteristics. The unique UC PL features, which is much different with the conventional rare earth activators, and universality of intrinsic defects in perovskite ferroelectrics open a new window for the development of UC PL materials.