Photoluminescence properties of novel Ba(2)Lu(5)B(5)O(17):Eu(3+) red emitting phosphors with high color purity for near-UV excited white light emitting diodes

A series of new red-emitting Ba(2)Lu(4.98−x)Eu(x)La(0.02)B(5)O(17) (0.1 ≤ x ≤ 1.0) phosphors were synthesized via the high-temperature solid-state reaction method. The phase formation of the as-synthesized Ba(2)Lu(4.48)Eu(0.5)La(0.02)B(5)O(17) phosphor was confirmed by powder X-ray diffraction analysis. It was found that La(3+) doping resulted in the reduction of LuBO(3) impurities and thus pure phase Ba(2)Lu(5)B(5)O(17) was realised. The morphology of Ba(2)Lu(4.48)Eu(0.5)La(0.02)B(5)O(17) phosphors was studied by field emission scanning electron microscopy (FE-SEM). As a function of Eu(3+) concentration the photoluminescence spectra and decay lifetimes were investigated in detail. Under excitation at 396 nm, a dominant red emission peak located at 616 nm ((5)D(0) → (7)F(2)) indicated that Eu(3+) ions mainly occupied low symmetry sites with a non-inversion center in Ba(2)Lu(4.48)Eu(0.5)La(0.02)B(5)O(17). The optimal Eu(3+) ion concentration was found to be x = 0.5 and the critical distance of Eu(3+) was determined to be 6.55 Å. In addition, the concentration quenching takes place via dipole–dipole interactions. The phosphors exhibited good CIE (Commission International de I'Eclairage) color coordinates (x = 0.643, y = 0.356) situated in the red region and a high color purity of 97.8%. Furthermore, the internal quantum efficiency and the thermal stability of Ba(2)Lu(4.48)Eu(0.5)La(0.02)B(5)O(17) phosphors were also investigated systematically. The results suggest that Ba(2)Lu(4.48)Eu(0.5)La(0.02)B(5)O(17) may be a potential red phosphor for white light-emitting diodes.