Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results ...Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results showed that the bands of BAM：Eu2＋ were of low band energy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM：Eu^2＋ showed stronger absorption intensity while Eu^2＋ occupied the BR sites instead of the mO sites. The concentration of Eu^2＋ at BR sites increased while that at mO sites decreased after Si-N doping. The influence of the variation of Eu^2＋ distribution on the spectra was stronger than the influence of the decrease of Eu^2＋ PDOS when SiN concentration was lower than 0.25, therefore the absorption and luminescence intensity of BAM：Eu^2＋ were enhanced. Mulliken population of Si-N bond was higher than A1-O bond, while that of Eu-N bond was higher than Eu-O bond as well, indicating that Si-N bonds and Eu-N bonds possessed higher covalence than Al-O bonds and Eu-N bonds respectively. The existence of Si-N bonds and Eu-N bonds enhanced the local covalence of Eu^2＋, hence the optical stability of BAM：Eu^2＋.展开更多
To discuss the function of Eu and Dy and their interaction in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ long afterglow material,the Eu and Dy single doped and their co-doped Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ were prepared.The samples wer...To discuss the function of Eu and Dy and their interaction in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ long afterglow material,the Eu and Dy single doped and their co-doped Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ were prepared.The samples were characterized by X-ray diffraction（XRD）,decay curves,photoluminescence（PL）,and thermoluminescence（TL）.The results indicate that Sr2 Mg Si2O7：Eu has afterglow properties,and the doping of Eu ion in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ can lower the depth of traps.Eu ion can not only serve as luminescence center,but also produce traps in the matrix,meanwhile,it also exerts certain influences on the traps produced by Dy in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋.The Dy ion can not act as luminescence center but relates to the change of the traps in the Sr2 Mg Si2O7 matrix.展开更多
Eu^(2+)and Mn^(2+)co-activated CaAlSiN_(3)red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to study...Eu^(2+)and Mn^(2+)co-activated CaAlSiN_(3)red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to study the luminescence characteristics,energy gap,and thermal stability in detail.CaAlSiN_(3)∶Eu^(2+)exhibits an extended emission band when stimulated with 450 nm blue light,which is caused by the 4f65d to 4f7 transition of Eu^(2+).Similar⁃ly,CaAlSiN_(3)∶Mn^(2+)displays a wide emission band centered at 628 nm,which results from Mn^(2+)’s transition from 4T1(4G)to 6A1(6S).When the ions of Mn^(2+)were combined into CaAlSiN_(3)∶Eu^(2+),the photoluminescence intensity of Eu^(2+)was greatly boosted because there was energy transfer and co-emission between Mn^(2+)and Eu^(2+).Beyond that,CaAlSiN_(3)∶Eu^(2+),Mn^(2+)emerges with splendid thermostability and high quantum efficiency,the quenching temperature surpasses 300℃,and the internal quantum efficiency is determined to be around 84.9%.The white LED was pack⁃aged with a combination of CaAlSiN_(3)∶Eu^(2+),Mn^(2+),LuAG∶Ce3+and a blue chip.At a warm white-light corresponding color temperature(3009 K)with CIE coordinates(0.4223,0.3748),the color rendering index Ra has reached 93.2.CaAlSiN_(3)∶Eu^(2+),Mn^(2+)would have great application potential as a red-emitting phosphor for white LEDs.展开更多
采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照...采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照片显示荧光粉为2μm的不规则颗粒。当激发波长为264 nm时,发射光谱出现四个尖锐的发射峰,分别位于591(^(5)D_(0)→^(7)F_(1))、619(^(5)D_(0)→^(7)F_(2))、657(^(5)D_(0)→^(7)F_(3))和693 nm(^(5)D_(0)→^(7)F_(4))。Eu^(3+)离子之间能量传递为电偶极子-电偶极子(d-d)相互作用。YMT∶0.14Eu^(3+)荧光粉的CIE色度坐标为(0.645,0.332),与红光标准色坐标(0.67,0.33)非常接近。变温PL光谱及热激活能计算结果显示荧光粉具有一定的热稳定性,因此YMT∶Eu^(3+)是一种具有潜在应用价值的LED红色荧光粉。展开更多
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.51072191）, One Hundred Talents Program of the Chinese Academy of Sciences, the National Basic Research Program of China （No.2012CB922004）, the National Natural Science Foundation of China （No.11105133）, and USTC- NSRL Association Funding （No.KY2060140005）.
文摘Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results showed that the bands of BAM：Eu2＋ were of low band energy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM：Eu^2＋ showed stronger absorption intensity while Eu^2＋ occupied the BR sites instead of the mO sites. The concentration of Eu^2＋ at BR sites increased while that at mO sites decreased after Si-N doping. The influence of the variation of Eu^2＋ distribution on the spectra was stronger than the influence of the decrease of Eu^2＋ PDOS when SiN concentration was lower than 0.25, therefore the absorption and luminescence intensity of BAM：Eu^2＋ were enhanced. Mulliken population of Si-N bond was higher than A1-O bond, while that of Eu-N bond was higher than Eu-O bond as well, indicating that Si-N bonds and Eu-N bonds possessed higher covalence than Al-O bonds and Eu-N bonds respectively. The existence of Si-N bonds and Eu-N bonds enhanced the local covalence of Eu^2＋, hence the optical stability of BAM：Eu^2＋.
文摘为研究稀土发光纳米晶的微观结构和形貌对发光性能的影响,用凝胶-微波干燥法和凝胶-烘箱干燥法制备了花状形貌的Sr3Al2O6晶体.研究了微波干燥和烘箱干燥两种不同的干燥方式对溶胶-凝胶法制备的Sr3Al2O6∶Eu2+发光粉体粒径、形貌、团聚程度、干燥时间及发光性能等的影响,结果表明采用微波干燥不仅可以大大缩短干燥所需时间,而且有利于减弱Sr3Al2O6∶Eu2+发光粉料的团聚和团聚程度,制得了颗粒分散均匀、团聚程度低、发光强度高的Sr3Al2O6∶Eu2+花状形貌粉体.研究了Sr3Al2O6∶Eu2+发光粉体的新型形貌对发光性能的影响,微波干燥法制备的均匀分散的花状形貌发光粉体发光强度高,余辉时间长达20 min.
文摘To discuss the function of Eu and Dy and their interaction in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ long afterglow material,the Eu and Dy single doped and their co-doped Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ were prepared.The samples were characterized by X-ray diffraction（XRD）,decay curves,photoluminescence（PL）,and thermoluminescence（TL）.The results indicate that Sr2 Mg Si2O7：Eu has afterglow properties,and the doping of Eu ion in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋ can lower the depth of traps.Eu ion can not only serve as luminescence center,but also produce traps in the matrix,meanwhile,it also exerts certain influences on the traps produced by Dy in Sr2 Mg Si2O7：Eu^2＋,Dy^3＋.The Dy ion can not act as luminescence center but relates to the change of the traps in the Sr2 Mg Si2O7 matrix.
文摘Eu^(2+)and Mn^(2+)co-activated CaAlSiN_(3)red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to study the luminescence characteristics,energy gap,and thermal stability in detail.CaAlSiN_(3)∶Eu^(2+)exhibits an extended emission band when stimulated with 450 nm blue light,which is caused by the 4f65d to 4f7 transition of Eu^(2+).Similar⁃ly,CaAlSiN_(3)∶Mn^(2+)displays a wide emission band centered at 628 nm,which results from Mn^(2+)’s transition from 4T1(4G)to 6A1(6S).When the ions of Mn^(2+)were combined into CaAlSiN_(3)∶Eu^(2+),the photoluminescence intensity of Eu^(2+)was greatly boosted because there was energy transfer and co-emission between Mn^(2+)and Eu^(2+).Beyond that,CaAlSiN_(3)∶Eu^(2+),Mn^(2+)emerges with splendid thermostability and high quantum efficiency,the quenching temperature surpasses 300℃,and the internal quantum efficiency is determined to be around 84.9%.The white LED was pack⁃aged with a combination of CaAlSiN_(3)∶Eu^(2+),Mn^(2+),LuAG∶Ce3+and a blue chip.At a warm white-light corresponding color temperature(3009 K)with CIE coordinates(0.4223,0.3748),the color rendering index Ra has reached 93.2.CaAlSiN_(3)∶Eu^(2+),Mn^(2+)would have great application potential as a red-emitting phosphor for white LEDs.
文摘采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照片显示荧光粉为2μm的不规则颗粒。当激发波长为264 nm时,发射光谱出现四个尖锐的发射峰,分别位于591(^(5)D_(0)→^(7)F_(1))、619(^(5)D_(0)→^(7)F_(2))、657(^(5)D_(0)→^(7)F_(3))和693 nm(^(5)D_(0)→^(7)F_(4))。Eu^(3+)离子之间能量传递为电偶极子-电偶极子(d-d)相互作用。YMT∶0.14Eu^(3+)荧光粉的CIE色度坐标为(0.645,0.332),与红光标准色坐标(0.67,0.33)非常接近。变温PL光谱及热激活能计算结果显示荧光粉具有一定的热稳定性,因此YMT∶Eu^(3+)是一种具有潜在应用价值的LED红色荧光粉。
