Improved thermal stability of Y3Al5O12:Ce3+ phosphor by SiO2 coating

摘要： In this paper, a heterogeneous precipitation method was adopted to coat a SiO2 layer on the surface of Y3Al5O12:Ce3+ phosphor. The surface morphologies, crystal phases, defect concentrations, luminescent properties and thermal stability of coated phosphors were investigated and compared with those of uncoated phosphor. A compact and homogeneous SiO2 layer on the surface of phosphor was determined by SEM-EDS, TEM, XRD and FT-IR results. Two thermoluminescent peaks were found at 112 oC and 248 oC on the thermoluminescence spectrum. Their intensities decreased slowly with the increasing coating amounts. It indicated that their corresponding defect concentrations were gradually reduced. Improved thermal stability was obtained by SiO2 coating in spite of a slight weakening of the emission intensity. The optimum theoretical coating amount was identified as 4%. Moreover, a structural modification mechanism on improved thermal stability of SiO2 coated Y3Al5O12:Ce3+ was proposed.