A narrow-band blue emitting phosphor Ca8Mg7Si9N22:Eu2+ for pc-LEDs

A narrow-band blue emitting phosphor Ca8Mg7Si9N22:Eu2+ was synthesized by a high temperature solid state reaction. Ca8Mg7Si9N22 crystallizes in a tetragonal space group P4(2)/nmc (No. 137) with a unit cell of a = 7.3469(6) angstrom and c = 10.3298(8) angstrom. The structure framework is composed of [SiN4] tetrahedra and a distorted square-pyramid [MgN5] polyhedron. Under UV light excitation, Ca8-xMg7Si9N22:xEu(2+) phosphors exhibit a narrow band emission peaking at 400 nm with a full width at half maximum similar to 34 nm. The CIE coordinates of Ca7.95Mg7Si9N22:0.05Eu(2+) are (0.1850, 0.0430) with a color purity of 89.22%. More importantly, the Ca8Mg7Si9N22:Eu2+ phosphor shows a remarkably high thermal quenching resistance, maintaining 92% photoluminescence emission intensity at 420 K and 75% at 700 K. Thus Eu2+ doped Ca8Mg7Si9N22 would be a promising blue phosphor even working under considerably high temperature (>700 K) conditions.