Understanding the luminescence in Yb3+ co-doped Sialon: Eu2+/Eu3+ transparent phosphor ceramic plate

The transparent Sialon phosphor ceramic plates were fabricated with varying amounts of Yb2O3 and Eu2O3. The hot press sintering technique was used to sinter the compact powders. The fabricated samples with the highest Yb2O3 concentration (10 wt%) and lowest Eu2O3 concentration (1 wt%) show a dominant alpha-Sialon phase, whereas the highest Eu2O3 (8 wt%) and lowest Yb2O3 (3 wt%) containing sample shows composite alpha/beta-Sialon phases as confirmed by the XRD analysis. The light transmittance was measured for 0.1 mm thick samples. The maximum light transmission of 60% was observed at 800 nm wavelength for the highest Yb2O3 added Sialon ceramics. Also, the higher Yb2O3 and lower Eu2O3 containing samples show a sharp orange luminescence at 590 nm, attributed to the parity allowed magnetic dipole induced D-5(0) -> F-7(1) transition of the Eu3+. These samples also produced upconversion luminescence as irradiated by 980 nm wavelength. The sample with the highest Eu2O3 addition exhibits broad greenish-yellow down-conversion emission with a sharp emission at 590 nm for composite alpha/beta-Sialon phases. The recorded broad emission ranges from green to red, offering a wide spectrum of visible light for lighting applications.