Preparation and luminescence properties of KLaSiO4 :Tb3+ phosphors.

Abstract

KLaSiO4 :Tb3+ phosphors were synthesized using the sol-gel method. The structure and luminescence properties of the materials were characterized using X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, thermogravimetry-differential thermal analysis, fluorescence spectra and calculated Commission Internationale de l'éclairage coordinates. The results showed that the material had a hexagonal structure, and that doping of Tb3+ did not change the crystal structure of KLaSiO4 . FTIR spectroscopy confirmed the existence of stretching vibrations of Si-O, bending vibrations of Si-O-Si, and asymmetric tensile vibrations of Si-O in KLaSiO4 . The excitation spectrum of the sample consisted of 4f7 →5d1 broadband absorption and the characteristic excitation peak of Tb3+ , the excitation peak at 232 nm belongs to the spin allowed 7 FJ →7 DJ transition of Tb3+ , the excitation peak at 268 nm belongs to the spin forbidden 7 FJ →9 DJ transition of Tb3+ , and the absorption band of 7 FJ →7 DJ transition is split. Under excitation at 232 nm, the emission peak of the sample was composed of the 5 D4 →7 FJ (J = 6, 5, 4, 3) energy level transition of Tb3+ . The highest emission peak is located at 543 nm, which belongs to the 5 D4 →7 F5 transition and emits green light. Concentration quenching occurred when the Tb3+ doping concentration was greater than 1% mol, the quenching mechanism was an electric dipole-electric dipole action. When the ratio of citric acid to total metal ions was 1:1 and the annealing temperature was 800°C, the surface defects of the phosphors were greatly reduced, the quenching effect was reduced, and the luminous intensity reached the maximum.