Local structure mediation and photoluminescence of Ce³⁺- and Eu³⁺-codoped YAG nanophosphors^®

Cerium and europium codoped yttrium aluminum garnet (YAG:Ce,Eu) nanophosphors were prepared by sol-gel method. We systematically explored the structure, composition, morphology and photoluminescence (PL) properties by using X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope, energy dispersive spectrometer, photoluminescence emission and excitation spectra techniques, and focused on clarifying the change of local structure surrounding Ce³⁺ ions by utilizing advanced quantitative ²⁷Al magic angle spinning nuclear magnetic resonance spectroscopy. The results show that the lattice constant slightly increases as the Ce³⁺ and Eu³⁺ ions incorporate, and the geometric distortion of local structure surrounding Ce³⁺ activator introduced by the incorporated Eu³⁺ coactivator causes the variation of crystal field, which results in red shift of Ce³⁺ PL emitting in YAG:Ce,Eu nanophosphor. Furthermore, the YAG:Ce,Eu nanophosphors could exhibit several sharp and narrow ⁵D₀ → ⁷F_J (J = 1∼4) emissions of Eu³⁺ ion besides the classic broad 5d₁ → 4f (²F_5/2, ²F_7/2) emissions of Ce³⁺ ion under near ultraviolet (UV) excitation.