Promising red phosphors LaNbO4:Eu3+, Bi3+ for LED solid-state lighting application

La0.75NbO4:Eu3+0.25 and La0.65NbO4:Eu3+0.25, Bi3+0.10 phosphors were synthesized by solid-state reaction method, and their photoluminescence properties were discussed in detail. With the increased incorporation of the co-activator Bi3+, the charge transfer (CT) bands of Nb5+→O2− and Eu3+→O2− (−280 nm) weakened and a new and significant broad band Bi3+−O2−(−330 nm) appeared, while the peaks at 395 and 466 nm assigned to f–f transitions of Eu3+ was slightly changed. Compared with the commercial phosphor Y2O2S:0.05Eu3+, La0.75Nb5O4:Eu3+0.25 and La0.65Nb5O4:Eu3+0.25, Bi3+0.10 phosphors emit brighter red light at 615 nm with line spectra upon the excitation of near UV light (395 nm) and exhibited the Commission International d'Eclairage (CIE) chromaticity coordinates (x=0.658, y=0.342) and (x=0.657, y=0.342) that are closer to the standard of national television standard committee (NTSC). The results showed that La0.75Nb5O4:Eu3+0.25 and La0.65Nb5O4:Eu3+0.25, Bi3+0.10 phosphors might be as promising red phosphors for near UV InGaN-based LED solid-state lighting application.