Energy transfer mechanism of Sr4Al14O25:Eu2+ phosphor

Long lasting blue-green-emitting Sr4Al14O25:Eu2+ phosphors were synthesized by solid-state reactions. The phosphors were investigated by X-ray diffraction (XRD) and fluorescence spectrophotometer. A pure phase of Sr4Al14O25: Eu2+ phosphor was obtained at 1250 °C. There are two different types of Eu emission centers in Sr4Al14O25:Eu2+ phosphor. The effects of the Eu2+ concentration and the reducing temperature on the distribution of Eu2+ among different sites were investigated. The energy transfer mechanism between two different emission centers was elucidated via the investigation of thermal damage influence on the phosphorescence spectra, that is, the energy emitted from an Eu1 emission center could be reabsorbed by an Eu2 emission center.