Eu2+-activated blue-emitting glass phosphor derived from Eu3+ exchanged USY zeolites by thermal treatment in reducing atmosphere

In this work, we report a facile method to prepare Eu2+ activated blue-emitting glass phosphor via loading Eu3+ into USY (Na28Si168Al28O384·240H2O, Si/Al ratio=6) zeolites' cavities followed by thermal treatment in reducing atmosphere. The zeolites powders containing Eu3+ were treated at different temperatures from 800 °C to 1200 °C in flowing 5%H2 + 95%N2 ambient. The photoluminescence properties were investigated on aspects of the emission and excitation spectra, internal quantum efficiency (IQE), thermal stability and the fluorescence lifetime. The XRD patterns showed that the sample calcined at 950 °C was of pure glassy state. Under the broad 200-430 nm excitation, a strong blue emission band peaked at 451 nm with a full width of half maximum (FWHM) value of 74 nm was observed for this sample. Under the 365 nm excitation, the samples treated at different temperatures showed monotone red shift in the emission peak wavelengths with the thermal treatment temperature increasing. Transparent glass sheets were obtained from the glass phosphor powders by spark plasma sintering (SPS) at 1200 °C, 1250 °C and 1300 °C. The optical transmittance and thermal conductivity of transparent glass sheets were measured. The results indicated that this glass phosphor may be a potential candidate material for white LEDs.