A novel orange-red Sr9Ga(PO4)7: Sm3+ phosphors for white light emitting diodes

Novel red-orange emitting phosphors Sr9Ga(PO4)(7):xSm(3+) were synthesized by solid state reaction for the first time. Their crystal structure, photoluminescence, thermo stability and lifetime were studied in detail. Results of XRD analysis suggests that Sm3+ is doped on the host lattice without any changes on crystal texture and photoluminescence emission spectra mainly consists of three emission bands attributed to transitions of (4)G(5/2) -> H-6(J) (J = 5/2, 7/2 and 9/2). Besides, the Dexter theory and lifetime were considered carefully to explain the concentration quench performance of phosphors and to reveal the mechanism for Sm3+ energy transfer. Especially, at 150 degrees C the phosphor still kept high energy efficiency relative to 97.34% of the best. Additionally, the thermal activation energy was determined to be 0.411 eV as calculated from the Arrhenius equation. All the results showed the potential application of these red-orange phosphors in n-UV white light-emitting diodes.