Synthesis and photoluminescence properties of a red emitting phosphor NaSr2(NbO3)5:RE3+ (RE=Sm, Pr) for white LEDs

Rare earth Sm3+, Pr3+ doped NaSr2(NbO3)5 red phosphors were successfully synthesized. X-ray diffraction analysis indicated that all the samples were single phased. The luminescence property was investigated in detail by diffuse-reflectance spectra and photoluminescence spectra measurement. Both NaSr2(NbO3)5:Sm3+ and NaSr2(NbO3)5:Pr3+ phosphors showed strong absorption in near ultraviolet region, which was suitable for application in LEDs. When excited by UV light, they both emitted bright red emission with CIE chromaticity coordinates (0.603, 0.397) and (0.669, 0.330), respectively. The optimal doping concentration of Sm3+ doped NaSr2(NbO3)5 was measured to be 0.04 and that for Pr3+ doped NaSr2(NbO3)5 was 0.01. The integral emission intensity was also measured and compared with the commercial red phosphor Y2O3:Eu3+. The results indicated that NaSr2(NbO3)5:RE3+ (RE=Sm, Pr) have potential to serve as a red phosphor for UV pumped white LEDs.