Photoluminescence properties of β-SiAlON:Yb2+, a novel green-emitting phosphor for white light-emitting diodes

We have synthesized Yb2+-activated Si(6-z)AlzOzN(8-)z (0.05 <= z <= 2.3, 0.03 mol% <= Yb2+ <= 0.7 mol%) green phosphors by solid-state reaction at 1900 degrees C for 2 h under a nitrogen pressure of 1.0 MPa. Phase purity, photoluminescence and its thermal quenching were investigated. A single phase was obtained for all values of z and Yb2+ concentration. A distinct emission band was observed at 540 nm originating from the 5d-4f electronic transition in Yb2+ under 480 nm excitation. The photoluminescence properties mainly depended on the Yb2+ concentration and chemical composition of the matrix. The resultant phosphor showed high thermal stability, that is, the emission intensity at 150 degrees C was about 82% of that measured at room temperature. The experimental results indicate that beta-SiAlON : Yb2+ is a potential green phosphor for white light-emitting diodes (LEDs), which use blue LEDs as the primary light source.