Potential red-emitting NaGd(MO4)2:R (M=W, Mo, R=Eu3+, Sm3+, Bi3+) phosphors for white light emitting diodes applications

Abstract NaGd(MO 4 ) 2 :R (M=W, Mo, R=Eu 3+ , Sm 3+ , Bi 3+ ) phosphors were synthesized by solid-state reaction. The structure and photoluminescence properties of the samples were characterized using X-ray powder diffraction and fluorescence spectrophotometry. The 5 D 0 → 7 F 2 transition of Eu 3+ , which led to a red emission of the phosphors, was dominantly observed in the photoluminescence spectra. The doped Bi 3+ and Sm 3+ efficiently sensitized the emission of Eu 3+ and effectively extended and strengthened the absorption of near-UV light with wavelengths ranging from 395 to 405 nm. In addition, energy transfers from Bi 3+ to Eu 3+ and from Sm 3+ to Eu 3+ occurred. The chromaticity coordinates of the obtained phosphors were close to the standard values of the National Television Standard Committee ( x =0.670, y =0.330). The results suggest that NaGd(WO 4 ) 2− y (MoO 4 ) y :Eu 3+ , Sm 3+ , Bi 3+ is an efficient red-emitting phosphor for light-emitting diode applications.