Highly Stable Red Oxynitride β-SiAlON:Pr³⁺ Phosphor for Light-Emitting Diodes

Abstract

Trivalent Pr3+-doped oxynitirde red phosphors β-SiAlON with composition Si6–zAlzOzN8–z:Prx (z = 0–2.0, x = 0.016) were synthesized by gas pressure sintering (GPS) at 1950 °C for 2 h. Red luminescence in the range 600–650 nm was detected upon excitation with 460 nm blue light, indicating that the phosphor can be excited by blue InGaN light-emitting diodes (LED). The crystallization and cell parameters of samples were investigated by powder X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM). Energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were further adopted to examine the effect of Al substitution on the microstructure. 27Al and 29Si solid-state nuclear magnetic resonance (NMR) data are consistent with SiN4–xOx and partially substituted AlN4–xOx tetrahedra. The temperature-dependent luminescence from the 1D2 and 3P0 states of Pr3+ were studied (10–573 K), and the integrated red emission from 600 to 650 nm increased with temperature (298–473 K). This unexpected phenomenon is proposed to be the result of two crossed excitation states in the configurational coordination diagram. This investigation reveals the superior characteristics of nitride compounds and the feasibility of doping Pr3+ into phosphor