Monitor local structure variation of Ce3+ activator in YAG:Ce nanophosphor with calcination temperature by nuclear magnetic resonance spectroscopy

Understanding the intrinsic relationship between photoluminescence (PL) properties and fine crystal structure is essential for developing excellent cerium doped Y3Al5O12 (YAG:Ce) nanophosphors. Herein, we studied the crystal structure evolution of YAG: Ce nanophosphors with calcination temperature via multiple characterization techniques, and focused on clarifying the local structure of Ce3+ activator by advanced quantitative Al-27 magic angle spinning nuclear magnetic resonance (Al-27 MAS NMR) spectroscopy. The results showed that the crystallinity of the YAG:Ce nanophosphors was improved and the lattice constant monotonously decreased with rising calcination temperature. Especially, as the calcination temperature increased from 830 to 1030 degrees C, more Ce3+ ions entered the first sphere of AlO6 groups and the symmetry of AlO4 species gradually increased in YAG: Ce nanophosphors, which caused the decrease of geometrical distortion surrounding Ce3+ activators. Due to the variations of fine structure, the PL intensity obviously increased with calcination temperature while its position remained constant. When the calcination temperature further increased to 1080 degrees C, CeO2 impurity formed in the nanophosphor, resulting in the increase of the quenching centers. (C) 2017 Elsevier B.V. All rights reserved.