Color-tunable luminescence properties of Sm.sup.3+/Dy.sup.3+ co-doped NaLa.sub.2 phosphors and their energy transfer mechanism

• Published in: Journal of materials science 2017-06, Vol.52 (11), p.6310
• Main Authors: Kong, Lingzhan, Xiao, Xiuzhen, Yu, Jun, Mao, Dongsen, Lu, Guanzhong
• Format: Article
• Language: English
• Subjects: LEDs
• ISSN: 0022-2461
• DOI: 10.1007/s10853-017-0863-6

The Sm.sup.3+, Dy.sup.3+ doped and Sm.sup.3+/Dy.sup.3+ co-doped NaLa(MoO.sub.4).sub.2 spherical phosphors were hydrothermally synthesized by the EDTA-2Na mediated method. Under the excitation of 297 nm, the quenching concentration of Sm.sup.3+ in NaLa(MoO.sub.4).sub.2 host was determined to be 13%, and the concentration quenching mechanism was discussed to be the electric quadrupole-quadrupole interaction. After Sm.sup.3+ and Dy.sup.3+ ions were co-doped into the NaLa(MoO.sub.4).sub.2 host, the energy transfer behaviors resulted from Dy.sup.3+ to Sm.sup.3+ ions were investigated by the help of the luminescent spectra of the obtained phosphors. By varying co-doping concentrations of Sm.sup.3+/Dy.sup.3+ ions, the emission color of NaLa(MoO.sub.4).sub.2:Sm.sup.3+/Dy.sup.3+ can be tuned from reddish-orange, pink and white to bluish-green. The CIE chromaticity coordinate, the correlated color temperature and the quantum efficiency of NaLa.sub.0.87(MoO.sub.4).sub.2:1%Sm.sup.3+, 12%Dy.sup.3+ were calculated to be (0.356, 0.320), 4353 K and 20%, respectively. Furthermore, in the temperature-dependent analysis, it presented good thermal stability, which can become a promising single-phased white-emitting phosphor for white LEDs devices. Based on these results, the possible energy transfer mechanism between Dy.sup.3+ and Sm.sup.3+ in NaLa(MoO.sub.4).sub.2:Sm.sup.3+/Dy.sup.3+ was also proposed.