Laboratory discovery of new phosphors for white-light light-emitting diodes （WLEDs） is still an im- perative challenge. A new yellow-emitting Sr9MgLi（PO4）7：Eu^2＋ phosphor was discovered based on the mineral-insp...Laboratory discovery of new phosphors for white-light light-emitting diodes （WLEDs） is still an im- perative challenge. A new yellow-emitting Sr9MgLi（PO4）7：Eu^2＋ phosphor was discovered based on the mineral-inspired pro- totype evolution and new phase construction strategy pro- posed by our group. Sr9MgLi（PO4）7：Eu^2＋ has been synthesized by using a high temperature solid-state method, and its phase structure and luminescence properties have been investigated in detail, and applied in WLED lamp. Sr9MgLi（PO4）7 phase is derived from the ]3-Ca3（PO4）2-type mineral structure. Upon 365 nm UV light excitation, the SrgMgLi（PO4）7：Eu^2＋ phosphor exhibits a broad emission band from 450 nm to 700 nm. The white-light LED lamp was fabricated based on the phosphor blends of the composition-optimized yellow-emitting Sr9MgLi （PO4）7：Eu2＋ and commercial blue-emitting BaMgAl10O17：Eu^2＋, and a 365 nm UV chip was used as the excitation source. The Ra, CCT value and CIE of the as-fabricated LEDs were found to be 83, 5,612 K, and （0.324, 0.358）, respectively. All the results indicate that Sr9MgLi（PO4）7：Eu^2＋ could be potential in the development of UV-pumped white-light LEDs.展开更多
Single phase of Ba1-x MgAl10O17 ： x Eu^2＋ （0.02≤ x ≤ 0. 14） phosphors was first successfully prepared by coprecipitation in aqueous medium with a “reverse strike” method, using oxalic acid and ammonia together...Single phase of Ba1-x MgAl10O17 ： x Eu^2＋ （0.02≤ x ≤ 0. 14） phosphors was first successfully prepared by coprecipitation in aqueous medium with a “reverse strike” method, using oxalic acid and ammonia together as precipitants. Completely crystallized phosphors were obtained at 1300 ℃, which is 300 ℃ lower than the temperature of solid-state reaction. Their photoluminescence was investigated under UV and VUV region, respectively. The emission spectra of Ba1-x MgAl10O17：xEu^2＋ samples excited by 254 or 147 nm showed a characteristic wide band with the peak centred at about 450 454 nm. Optimum emission intensity reached at x = 0.1 and then concentration quenching occurred. The synthesized phosphor shows 10% higher emission intensity than that prepared by solid-state reaction.展开更多
The mechanisms of thermal,ultraviolet and vacuum ultraviolet radiation degradation behaviors of the Eu2+,Mn2+ co-doped BaMgAl10O17 phosphors were investigated comparatively.The result indicated that the Mn2+ ions whic...The mechanisms of thermal,ultraviolet and vacuum ultraviolet radiation degradation behaviors of the Eu2+,Mn2+ co-doped BaMgAl10O17 phosphors were investigated comparatively.The result indicated that the Mn2+ ions which replaced the Mg2+ sites in the sample were stable and negligibly influenced by treatments.The oxidation and migration of Eu2+ ions primarily caused the thermal degradation of the sample.The vacuum ultraviolet radiation degradation was primarily because of the migration of Eu2+.The ultraviolet radiation increased traps which trended the Eu2+r to be in a metastable state,leading to the ultraviolet radiation degradation of the sample.The vacuum ultraviolet excited luminous loss of samples after ultraviolet radiation partly originated from the interruption of energy transfer from the host to activators by traps.展开更多
Heterogeneous precipitation method was used to prepared surface coating on self-made BaMgAl10O17 : Eu phosphor. Results illustrate that the coating film can be silicon dioxide in amorphous state with 50 nm in thicknes...Heterogeneous precipitation method was used to prepared surface coating on self-made BaMgAl10O17 : Eu phosphor. Results illustrate that the coating film can be silicon dioxide in amorphous state with 50 nm in thickness. Photolumi-nescence results indicate that the coating layer presents an observable improved effect on the enhancement of thermal stability. When baked at 600℃for 1 h, the luminance of coated BAM keeps at 92% higher than that of uncoated BAM by 23% . This protective effect can be attributed to the high compact degree and uniformity of this amorphous SiO2 coating film which is served as a diffusion block layer to inbreak oxygen atom, thus releases the oxidation extent of Eu2 + effectively.展开更多
基金supported by the National Natural Science Foundation of China (51722202, 91622125 and 51572023)Natural Science Foundation of Beijing (2172036)
文摘Laboratory discovery of new phosphors for white-light light-emitting diodes （WLEDs） is still an im- perative challenge. A new yellow-emitting Sr9MgLi（PO4）7：Eu^2＋ phosphor was discovered based on the mineral-inspired pro- totype evolution and new phase construction strategy pro- posed by our group. Sr9MgLi（PO4）7：Eu^2＋ has been synthesized by using a high temperature solid-state method, and its phase structure and luminescence properties have been investigated in detail, and applied in WLED lamp. Sr9MgLi（PO4）7 phase is derived from the ]3-Ca3（PO4）2-type mineral structure. Upon 365 nm UV light excitation, the SrgMgLi（PO4）7：Eu^2＋ phosphor exhibits a broad emission band from 450 nm to 700 nm. The white-light LED lamp was fabricated based on the phosphor blends of the composition-optimized yellow-emitting Sr9MgLi （PO4）7：Eu2＋ and commercial blue-emitting BaMgAl10O17：Eu^2＋, and a 365 nm UV chip was used as the excitation source. The Ra, CCT value and CIE of the as-fabricated LEDs were found to be 83, 5,612 K, and （0.324, 0.358）, respectively. All the results indicate that Sr9MgLi（PO4）7：Eu^2＋ could be potential in the development of UV-pumped white-light LEDs.
基金Project supported bythe National Natural Science Foundation of China (50272026) ,the Excellent Young Teachers ProgramofMOE,China (EYTP) and the Natural Science Foundation of Gansu Province (ZS031-A25-033-C)
文摘Single phase of Ba1-x MgAl10O17 ： x Eu^2＋ （0.02≤ x ≤ 0. 14） phosphors was first successfully prepared by coprecipitation in aqueous medium with a “reverse strike” method, using oxalic acid and ammonia together as precipitants. Completely crystallized phosphors were obtained at 1300 ℃, which is 300 ℃ lower than the temperature of solid-state reaction. Their photoluminescence was investigated under UV and VUV region, respectively. The emission spectra of Ba1-x MgAl10O17：xEu^2＋ samples excited by 254 or 147 nm showed a characteristic wide band with the peak centred at about 450 454 nm. Optimum emission intensity reached at x = 0.1 and then concentration quenching occurred. The synthesized phosphor shows 10% higher emission intensity than that prepared by solid-state reaction.
基金supported by the National Natural Science Young Foundation of China(Grant No.10904057)the Fundamental Research Funds for the Central Universities(Grant No.Lzjbky-2011-125)+1 种基金the National Science Foundation for Distinguished Young Scholars(Grant No.50925206)the National Natural Science Foundation of China(Grant No. 10874061)
文摘The mechanisms of thermal,ultraviolet and vacuum ultraviolet radiation degradation behaviors of the Eu2+,Mn2+ co-doped BaMgAl10O17 phosphors were investigated comparatively.The result indicated that the Mn2+ ions which replaced the Mg2+ sites in the sample were stable and negligibly influenced by treatments.The oxidation and migration of Eu2+ ions primarily caused the thermal degradation of the sample.The vacuum ultraviolet radiation degradation was primarily because of the migration of Eu2+.The ultraviolet radiation increased traps which trended the Eu2+r to be in a metastable state,leading to the ultraviolet radiation degradation of the sample.The vacuum ultraviolet excited luminous loss of samples after ultraviolet radiation partly originated from the interruption of energy transfer from the host to activators by traps.
基金Project supported by Jiangsu Province High Tech Foundation (BG2002024)
文摘Heterogeneous precipitation method was used to prepared surface coating on self-made BaMgAl10O17 : Eu phosphor. Results illustrate that the coating film can be silicon dioxide in amorphous state with 50 nm in thickness. Photolumi-nescence results indicate that the coating layer presents an observable improved effect on the enhancement of thermal stability. When baked at 600℃for 1 h, the luminance of coated BAM keeps at 92% higher than that of uncoated BAM by 23% . This protective effect can be attributed to the high compact degree and uniformity of this amorphous SiO2 coating film which is served as a diffusion block layer to inbreak oxygen atom, thus releases the oxidation extent of Eu2 + effectively.
