Luminescent properties of novel red-emitting M 7 Sn(PO 4 ) 6 :Eu 3+ (M = Sr, Ba) for light-emitting diodes.

Novel red-emitting phosphors, Eu3+ -activated M7 Sn(PO4 )6 (M = Sr, Ba), were synthesized at 1200°C by conventional solid-state reaction method. The luminescent properties of M7 Sn(PO4 )6 :Eu3+ (M = Sr, Ba) phosphors were investigated, and the critical concentration of the activator (Eu3+ ) concentration were found to be 0.175 mol and 0.21 mol per formula unit for Sr7-x Sn(PO4 )6 :xEu3+ and Ba7-x Sn(PO4 )6 :xEu3+ , respectively. These phosphors presented red luminescence under the excitation of 395 or 465 nm, perfectly matching with the emissions wavelength of near-ultraviolet (UV) light-emitting diodes (LEDs) and InGaN blue LED.