Optical properties of zinc borate glasses dispersed with Eu-doped SiAlON for white LED applications

Ca-α-SiAlON:Eu2+ oxynitride phosphors are typical luminescent materials with high thermal tolerances. A series of zinc borate glass samples (xZnO-(100-x)B2O3; mol%) were prepared for investigating their ability to disperse Ca-α-SiAlON:Eu2+ phosphor powders. Phosphor in glass (PiG) was prepared with SiAlON and zinc borate glass through a melting process. In the x = 45-60 range, PiGs could be obtained without the degradation of the SiAlON phosphors. The PiG composed of x = 50 glass exhibited the highest quantum efficiency. The glass structures of the mother glasses were investigated by Raman spectra; there was a decrease in the boroxol ring, and pyroborate and orthoborate were formed, on increasing x. From the XRD and SEM images, it was established that ZnAl2O4 was formed around the SiAlON powders in PiGs with x = 50, 55, and 60, respectively. This suggests that the partial crystallizations in the PiGs are effective in enhancing the photoluminescence of the SiAlON phosphors.