Effects of heat-treatment with a flux under reduced atmosphere on photoluminescence of orange-red emitting CaSrSiO4:Eu2+ phosphors

Abstract

The effects of heat-treatments with various conditions such as temperature, atmosphere and luxing agents on photoluminescence properties of CaSiSiO4:Eu2+ phosphors were investigated in detail. X-ray absorption fine structure of CaSrSiO4:Eu2+ phosphors heat-treated at various temperatures revealed that the reduction from Eu3+ to Eu2+ in the precursor powder was effectively promoted at the temperatures higher than melting temperature of luxing agent. We found that red shift of emission peak was caused by pre-heat-treatment under a reduced atmosphere. The effect of fluxing agents such as BaCl2, SrCl2, CaCl2 on photoluminescence properties of CaSrSiO4:Eu2+ phosphor was also examined. The results indicate that CaSrSiO4:Eu2+ phosphor heat-treated using BaCl2 lux shows high emission eficiency. We also recognized that the small amounts of Ba2+ was incorporated into CaSrSiO4 lattice due to the ion exchange.