Luminescence properties of a green-emitting Eu²⁺-doped Sr-containing SiAlON phosphors by gas pressure sintering

A green-emitting platelet Eu²⁺ doped SiAlON phosphor with a composition of Sr₆Si_25.6Al_6.4N_41.6O_4.4 is developed by gas pressure sintering method at 1800 °C and 0.5 MPa of N₂ for 10 h, which is highly luminescent under the excitation of ultraviolet to blue light and shows green emission, peaking around 510 nm with the FWHM of 65 nm, the emission is ascribed to the 4f⁶5d¹–4f⁷ transition of Eu²⁺ ions. The phase purity and crystal structure are investigated in this work. Quenching concentration of the phosphors is found to be 0.03 mol fraction. The thermal quenching properties of the green phosphors with different Eu²⁺ concentrations are also investigated. Better thermal stabilities can be obtained with lower Eu²⁺ concentration, the emission intensity at 200 °C remains 68 % of that measured at room temperature when Eu²⁺ concentration is 0.03, which is much better than standard orthosilicate phosphors. The internal and external quantum efficiencies of the green phosphor are 85 and 64 % upon the 460 nm excitation. The interesting properties of the phosphor make it a competitive candidate for UV or blue chip based white LEDs.