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.