Alumina encapsulated SrAl2O4:Eu, Dy phosphors

Alumina encapsulation on SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors by a new type of chemical precipitation process was reported for the first time to the best of our knowledge. X-ray fluorescent measurements revealed that using glycol instead of the distilled water as the disperse medium is helpful to alumina encapsulation. Scanning electron micrographs and BET measurements showed that a dense and homogeneous off-white alumina layer was formed on the phosphor surface after encapsulation. Water resistance and heat resistance measurements showed that when the encapsulation amount reached to 5 wt.% (fed value), the encapsulated phosphors began to show good water resistance and heat resistance with little loss of persistent phosphorescence.