Promising red phosphors LaNbO 4:Eu 3+, Bi 3+ for LED solid-state lighting application

Abstract

La 0.75NbO 4:Eu 3+ 0.25 and La 0.65NbO 4:Eu 3+ 0.25, Bi 3+ 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 Bi 3+, the charge transfer (CT) bands of Nb 5+→O 2− and Eu 3+→O 2− (−280 nm) weakened and a new and significant broad band Bi 3+−O 2−(−330 nm) appeared, while the peaks at 395 and 466 nm assigned to f–f transitions of Eu 3+ was slightly changed. Compared with the commercial phosphor Y 2O 2S:0.05Eu 3+, La 0.75Nb 5O 4:Eu 3+ 0.25 and La 0.65Nb 5O 4:Eu 3+ 0.25, Bi 3+ 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 La 0.75Nb 5O 4:Eu 3+ 0.25 and La 0.65Nb 5O 4:Eu 3+ 0.25, Bi 3+ 0.10 phosphors might be as promising red phosphors for near UV InGaN-based LED solid-state lighting application.