A potential red-emitting phosphor with high color-purity for near-UV light emitting diodes

New red tungstates phosphors, Na5La1−xLnx(WO4)4 (Ln = Eu, Sm) and Na5Eu1−xSmx(WO4)4, were prepared by solid-state reaction technique. And their structure and photo-luminescent properties were investigated. The introduction of Sm3+ broadened the excitation band around 400 nm of the phosphors, and strengthened the red emission. And the possible energy transfer process from Sm3+ to Eu3+ is discussed. The single red LED was fabricated by combining InGaN chip with Na5Eu0.94Sm0.06(WO4)4 as red phosphor, intense red light can be observed by naked eyes. Then the phosphor Na5Eu0.94Sm0.06(WO4)4 may be a good candidate for red component of near-UV InGaN-based W-LEDs, because of efficient red-emitting with broadened absorption around 400 nm and appropriate CIE chromaticity coordinates (x = 0.65, y = 0.34).

► The excitation bands around 400 nm of Na5Eu1−xSmx(WO4)4 are broadened by Sm3+–Eu3+ co-doping.
► The phosphor Na5Eu0.94Sm0.06(WO4)4 exhibits efficient red-emitting under near-UV excitation, compared with. Na5Eu(WO4)4.
► The possible energy transfer process from Sm3+ to Eu3+ in these compounds was discussed.
► Bright red light can be observed from the red LED-based Na5Eu0.94Sm0.06(WO4)4.