Sol-gel elaboration and characterization of YAG: Tb3+ powdered phosphors

Pure and Tb3+-doped Y3Al5O12 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 (27Al MAS NMR). Pure highly crystalline YAG powders were obtained from 900◦C. Laser induced luminescence spectra as well as decay times versus Tb3+ concentration were also studied. The well known 5D3 → 5D4 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:Tb3+ powders was determined. C 2006 Springer Science + Business Media, Inc.