Synthesis and photoluminescence properties of beta-sialon: Eu2+ (Si6-zAlzOzN8-z : Eu2+)

Divalent europium-activated p-sialon (Si 6-z Al z O z N 8-z , 0.1 ≤ S≤ S 2.0) phosphors with dopant concentration varying in the range of 0.02-1.5 mol % were synthesized by firing the powder mixture of α-Si 3 N 4 , AIN, Al 2 O 3 , and Eu 2 O 3 at 2000°C for 2 h under a nitrogen-gas pressure of 1.0 MPa. The phase purity, microstructure, luminescence spectra, and thermal quenching of the fired β-sialon:Eu 2+ phosphors were investigated. The samples with lower z values (z≤ 1.0) showed higher phase purity, finer and more uniform particle size, and higher emission. Green luminescence of Eu 2+ (λ em = 528-550 nm) was achieved in p-sialons upon near-ultraviolet (NUV) or blue-light excitations. Furthermore, the β-sialon:Eu 2+ phosphors had small thermal quenching, the emission intensity of which attained 84-87% of that measured at room temperature. The experimental data clearly indicates that β-sialon:Eu 2+ has great potentials as a down-conversion green phosphor for white light-emitting diodes (LEDs) utilizing NUV or blue LEDs as the primary light source.