Microwave synthesis of red-emitting Ca2Si5N8:Eu2+ phosphor and its photoluminescence properties for white-LEDs

A microwave synthesis method has been developed for synthesis of Ca2Si5N8:Eu2+ phosphor and its photoluminescence properties were investigated. Ca, Si, and Eu2O3 powders were used as the reactants serving as the sources of the Ca, Si and Eu. Addition of NaN3 NH4Cl and Si3N4 powders was found to increase significantly the product yield. These powders were mixed and pressed into a compact which was then embedded in AlN powder inside a BN crucible. The crucible was then placed at the center of the microwave cavity (TE103 single-mode). The microwave synthesis was performed at a microwave power (2.45 GHz) of 600 W for 1 h in a flowing 90%N2-10%H2 gas at one atmosphere. The effects of process parameters on the product yield were investigated and a reaction mechanism was proposed. The synthesized Ca2Si5N8:Eu2+ phosphor absorbs light in the region of 240–520 nm and shows a single broad band emission in the region of 550–700 nm (peaking at 596–606 nm). The peak emission intensity at an optimized Eu2O3 molar ratio (0.03) was measured to be ∼106% of the commercial YAG:Ce3+ (P46-Y3) phosphor.