A surface corrosion and expansion mechanism on thermal degradation of SrAl2O4:Eu2+, Dy3+

The thermal degradation of SrAl2O4:Eu2+, Dy3+ phosphor limits its application in high temperature products. To clarify its thermal degradation mechanism, a heat-treatment process was carried out, and the interrelation of luminescent degradation, surface chemical composition and heat-treatment temperature was investigated. The results revealed that the afterglow properties degraded obviously with the increasing heat-treatment temperature, while the instantaneous emission intensity appeared two maximum values. According to the luminescent mechanism of long afterglow materials and the results of thermoluminescence spectra, two maximum values corresponded to the destruction of two trap levels at different temperatures. X-ray photoelectron spectroscopy results showed that the element composition of Sr and O on the phosphor surface increased with the increasing heat-treatment temperature, confirming that a SrO layer formed on the surface. Based on above results, we proposed a surface corrosion and expansion mechanism on the thermal degradation of SrAl2O4: Eu2+, Dy3+. (C) 2018 Elsevier B.V. All rights reserved.