Highly Stable Red Oxynitride β-SiAlON:Pr 3+ Phosphor for Light-Emitting Diodes

Trivalent Pr 3+ -doped oxynitirde red phosphors β-SiAlON with composition Si 6– z Al z O z N 8– z:Pr x ( 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. 27 Al and 29 Si solid-state nuclear magnetic resonance (NMR) data are consistent with SiN 4– x O x and partially substituted AlN 4– x O x tetrahedra. The temperature-dependent luminescence from the 1 D 2 and 3 P 0 states of Pr 3+ 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 Pr 3+ into phosphor.