β-Sialon:Eu phosphor-in-glass: A robust green color converter for high power blue laser lighting

Solid state laser lighting is superior to white light-emitting diodes in brightness, efficiency and color gamut, which require thermally robust color converters that can be endured by high power blue laser irradiation. Due to this, the application of bulk phosphor-in-glass (PiG) luminescent materials could be of great interest. Here, we report a green-emitting PiG material by co-firing β-Sialon:Eu phosphor powders with the ZnO-B₂O₃-BaO-Al₂O₃ glass frits at 630-660 °C for 20-80 min in air. The microstructure, photoluminescence spectra, quantum efficiency, transmittance and thermal quenching of the β-Sialon:Eu PiG materials were investigated. The microstructural analysis indicated that β-Sialon:Eu phosphor powders were uniformly dispersed in the glass matrix without any interfacial reactions. The luminescence efficiency and transparency of the PiG materials were largely dependent on the phosphor concentration, firing temperature and dwell time. Under the blue laser excitation, the optimized PiG sample consisting of 5 wt% β-Sialon:Eu showed a linear relationship between the luminous flux and the incident laser power when the blue laser flux density was below 0.7 W mm^-2, indicating its potential applications in solid state laser lighting.