Sol-gel elaboration and characterization of YAG: Tb~(3+) powdered phosphors

摘要

Pure and Tb~(3+) doped Y_3Al_5O_12 materials have been successfully synthesized from sol-gel based alkoxide precursors. Their formation process, structure and microstructure were examined by means of X-ray diffraction (XRD), thermal analysis combined with infrared spectroscopy (TG-IR / TDA), infrared spectroscopy (IR), scanning electron microscopy (SEM) and solid-state NMR study (~(27)Al MAS NMR). Pure highly crystalline YAG powders were obtained from 900°C. Laser induced luminescence spectra as well as decay times versus Tb~(3+) concentration were also studied. The well known ~(5)D_3 → ~(5)D_4 cross-relaxation and concentration quenching phenomena were observed. Decay times of the green emission (λem = 544 nm) were mainly found to be exponential with time constant lower than 5 ms. Finally, the optimal terbium concentration for the luminescence efficiency of YAG: Tb~(3+) powders was determined.