Jiansheng Huang,Ronghui Liu,Yuanhong Liu,Yunshen Hu,Guantong Chen,Chunpei Yan,Junhang Tian,Bin Hu
Eu 2+ activated BaSi 2 O 2 N 2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF 2 , Na 2 CO 3 and NH 4 Cl were used as the fluxes. The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photoluminescence properties. The results indicate that with the addition of BaF 2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi 2 O 2 N 2 :Eu 2+ phosphor can be improved effectively. The photoluminescence intensity of BaSi 2 O 2 N 2 :Eu 2+ phosphor with BaF 2 as flux gets enhanced obviously, which is much higher than that of Na 2 CO 3 , NH 4 Cl and without flux. The optimum content of BaF 2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi 2 O 2 N 2 :Eu 2+ phosphor prepared with BaF 2 flux rises to 141%, meanwhile, the phosphors with BaF 2 flux exhibits low thermal quenching. The results indicate that the BaSi 2 O 2 N 2 :Eu 2+ is sort of promising bluish-green phosphor for application in full-spectra LED.
He Youyi,Liu Jun,Gao Yalei,Yan Lijuan,Lv Fengzhen,Liu Fuchi,Long Lizhen
Mn 4+ -activated phosphors have become a hotspot in the development of inorganic red phosphors due to the fascinating photoluminescent properties. Herein, the synergetic manipulation of the flux effect and charge compensation was employed to improve the performance of Mn 4+ -activated CaAl 12 O 19 red phosphors. The crystallinity was improved by appropriate Zn 2+ -doping, while nonradiative transition between Mn 4+ ions is reduced by charge compensation of the formation of Mn 4+ –Mg 2+ pairs with Mg 2+ dopants. Thus, the emission of Mn 4+ -activated CaAl 12 O 19 red phosphors has been remarkably enhanced. The low probability of nonradiative transition between Mn 4+ ions was demonstrated by the thermal stability analysis. To depict the luminescent process, the crystal-field strength ( D q ), and Racah parameters ( B and C ) were calculated to determine the sequence of the energy levels. Meanwhile, the warm WLEDs with high CRI and low CCT were obtained using the prepared phosphors as red-emitting composition. Our results clearly suggested that the synergetic strategy by combining the flux effect and charge compensation is an effective method to enhance the luminescence of CaAl 12 O 19 :Mn 4+ , and CaAl 12 O 19 :Mn 4+ /Zn 2+ /Mg 2+ red-emitting phosphors, which have potential application value in warm WLEDs.
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