Doping level dependence of the structure and luminescence properties of LaBO3: Tb3+ phosphors

Tb 3+ doped LaBO 3 phosphors with various doping levels were synthesized by hydrothermal and post-calcination methods. The structure, morphology, chemical composition, and optical properties of the samples were studied by X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), Photoluminescence spectroscopy (PL). XRD patterns reveal that Tb 3+ doped LaBO 3 crystals with monoclinic or orthorhombic structures can be obtained by adjusting the doping content of Tb 3+ . The XPS and EDS results indicate that the elements of La, O, B, and Tb were uniformly distributed in the samples, and some doping Tb 3+ were oxidized to Tb 4+ . The prepared Tb 3+ doped LaBO 3 phosphors emit green emission at 543 nm under 271 nm excitation. The luminescence intensity is affected by the Tb 3+ doping level, and concentration quenching will be observed due to an electric quadrupole-electric quadrupole interaction (p-p) process when the Tb 3+ doping amount rises above 22 %. In particular, the luminescence properties of the Tb 3+ doped LaBO 3 phosphors are dramatically affected by the structure of the samples, and the luminescence intensity of the samples with orthorhombic structure is significantly higher than those with monoclinic structure. The decay curves of samples exhibit a double exponential behavior, and the average luminescence lifetime decreases with an increase in Tb 3+ doping levels.