Sr3B2O6：Eu3+,Li+荧光粉的合成与发光性能

采用高温固相法合成Sr₃B₂O₆：Eu³⁺,Li⁺红色荧光粉,考察了激活剂Eu³⁺和电荷补偿剂Li⁺浓度对Sr₃B₂O₆：Eu³⁺,Li⁺荧光粉发光性能的影响。结果表明：适量掺杂Eu³⁺、Li⁺离子并不改变Sr₃B₂O₆的结构。当Eu³⁺掺杂量为4%、Li⁺的掺杂量为8%时,在900 ℃下灼烧2 h可以得到发光性能最佳的Sr_2.9B₂O₆：0.04Eu³⁺,0.08Li⁺红色荧光粉。以394 nm的近紫外光激发时,Sr₃B₂O₆：Eu³⁺,Li⁺荧光粉发射出红光,对应于Eu³⁺的4f-4f 跃迁,其中以614 nm附近的⁵D₀→⁷F₂跃迁发光最强,是一种有潜力用于白光LED的红色荧光粉。     

白光LED用红色荧光粉Sr2EuxGd1-xAlO5的制备及其发光性质

用高温固相反应法合成了Sr₂Eu_xGd_1-xAlO₅红色荧光粉,研究了荧光粉的晶体结构和发光性质。在紫外光和近紫外光激发下,样品的发射光谱由Eu³⁺的⁵D₀→⁷F_J(J=0,1,2,3,4) 特征发射组成,其中Eu³⁺离子的⁵D₀→⁷F₁(λ=590 nm)和⁵D₀→⁷F₂(λ=622 nm)跃迁发射的强度最大。当Eu³⁺离子的摩尔分数为 0.75时,样品的发光最强。研究结果表明,Sr₂Eu_xGd_1-xAlO₅荧光粉是一种在近紫外芯片白光LED上有应用前景的红光荧光粉。     

Ba5SiO4Cl6: Yb3+, Er3+, Li+荧光粉的制备及上转换发光性质研究

本文采用高温固相反应法制备了Ba₅SiO₄Cl₆: Yb³⁺, Er³⁺, Li⁺ 荧光粉, 并对其上转换发光性质及其发光机理进行了研究. 在980 nm 激光的激发下, Ba₅SiO₄Cl₆: Yb³⁺, Er³⁺ 荧光粉呈现较强的红色(662 nm) 和较弱的绿色(550 nm) 的上转换发光, 红色和绿色的上转换发光分别对应于Er³⁺ 离子的⁴S_3/2/²H_11/2→⁴I_15/2 和⁴F_9/2→⁴I_15/2 跃迁, 且随着掺杂的Er³⁺ 和Yb³⁺ 离子浓度增加, 样品的上转换发光强度增加, 这是因为Yb³⁺ 离子和Er³⁺ 离子之间的能量传递效率增加引起的. 在0.5—0.8 W 功率激发下,样品属于双光子发射, 而在0.9—1.2 W 功率激发下样品具有新的上转换发光机理——光子雪崩效应. 探讨了Li⁺ 掺杂对Ba₅SiO₄Cl₆: Yb³⁺, Er³⁺ 样品的上转换发光性质的影响, Li⁺ 离子的掺杂引起Ba₅SiO₄Cl₆:Yb³⁺, Er³⁺ 上转换发光强度增加, 这是由于Li⁺ 离子的掺入降低了晶体场的对称性引起的.     

蓝光激发白光LED用深红色荧光粉 Ca1-x-yWO4∶xPr3+, yLi+的制备与表征

用高温固相法合成了用于白光LED的Ca_1-x-yWO₄∶xPr³⁺,yLi⁺ 红色荧光粉。用XRD、SEM和荧光分光光度计,对试样的晶体结构、表面形貌和发光性能进行表征。所合成的样品为四方晶系。经预先球磨的样品颗粒比较均匀,粒径较小。荧光粉的激发峰位于440~500 nm的宽带内,主要发射峰位于602,620,651 nm,对应于Pr³⁺的¹D₂→³H₄、³P₀→³H₆和³P₀→³F₂特征跃迁发射, 651 nm处的强度最大。同时还研究了Pr³⁺、Li⁺的掺杂浓度以及助熔剂的加入对样品性能的影响。实验结果表明,所合成的Ca_1-x-yWO₄∶xPr³⁺,yLi⁺是可用于蓝光芯片激发的白光LED用红色荧光粉。     

Sr3Gd0.5-xTb0.5(BO3)3∶xEu3+的发光性质及能量传递

采用高温固相法制备了Sr₃Gd_0.5-xTb_0.5(BO₃)₃∶xEu³⁺系列荧光粉,并研究了其发光性质与能量传递过程。Sr₃Gd_0.5-xTb_0.5(BO₃)₃∶xEu³⁺系列荧光粉在300~400 nm的近紫外光有效激发下产生489,544,594,614,624 nm的发射谱线,分别对应于Tb³⁺和Eu³⁺的特征跃迁。荧光寿命测试表明,随着Eu³⁺掺杂浓度的增大,Tb³⁺寿命逐渐缩短,证实该体系中存在Tb³⁺→Eu³⁺的能量传递过程,能量传递效率最大值为20.53%。在对Tb³⁺和Eu³⁺的能级结构进行分析的基础上,进一步探讨了Tb³⁺→Eu³⁺能量传递过程。Sr₃Gd_0.5-xTb_0.5-(BO₃)₃∶xEu³⁺系列荧光粉具有良好的红色发光性质,是潜在的可以应用于白光LED的光转换材料。     

新型红色荧光粉Sr2ZnMoO6:Sm3+的制备与发光性能

采用高温固相法合成了Sr₂ZnMoO₆:Sm³⁺新型红色荧光材料,并对其发光特性进行了研究。XRD测量结果表明所制备样品为纯相Sr₂ZnMoO₆晶体。样品的发射光谱由一系列锐谱组成,分别位于563 nm(⁴G_5/2→⁶H_5/2)、598 nm(⁴G_5/2→⁶H_7/2)、607 nm(⁴G_5/2→⁶H_7/2)和645 nm(⁴G_5/2→⁶H_9/2),最强发射为645 nm。样品激发光谱由电荷迁移带CT和Sm³⁺离子的特征激发峰组成,主激发峰位于284 nm(CT)和403 nm(⁶H_5/2-⁴L_13/2)。 随着Sm³⁺浓度的增大, Sr_2-xZnMoO₆:xSm³⁺材料的发光强度先增大后减小, 在x≥2%时,发生浓度猝灭现象。根据Dexter理论分析其猝灭机理为电偶极-电偶极相互作用。比较了Li⁺、Na⁺和K⁺作为电荷补偿剂的作用,发现均使Sr₂ZnMoO₆:Sm³⁺材料的发射强度得到增强,但以Li⁺补偿效果最为显著。     

Bi3+掺杂对Sr2MgSi2O7∶Eu2+荧光粉的结构及发光性能的影响

采用溶胶-凝胶法在还原气氛下制备了Sr₂MgSi₂O₇∶Eu²⁺,xBi³⁺(x=0,0.02,0.04,0.06,0.08,0.1)荧光粉,并用XRD、TG-DTA及激发与发射谱仪对样品的结构及发光性能进行了表征。结果发现:单掺杂Bi³⁺的Sr₂MgSi₂O₇样品的发射光谱所用的材料的激发光谱为一主峰为286 nm的宽带谱,这是由于激发态时Bi³⁺的³P₁→¹S₀电子能级跃迁而造成的;单掺杂Eu²⁺的Sr₂MgSi₂O₇样品的发射光谱所用的材料的激发光谱为一主峰为358 nm的宽带谱,这是典型的Eu²⁺的4f⁶5d¹→4f⁷跃迁而引起的。当Bi³⁺离子掺杂到Sr₂MgSi₂O₇∶Eu²⁺样品的摩尔分数为0.04时,样品的发射强度是未掺杂Bi³⁺离子样品的1.9倍。     

Mg5SnB2O10:Eu3+,Bi3+—一种用于发光二极管的红色荧光粉的制备及其发光性能的研究

采用高温固相法成功合成了单一相的Eu³⁺,Bi³⁺共掺的Mg₅SnB₂O₁₀红色荧光粉,并通过X射线衍射、漫反射光谱、光致发光光谱等手段对该体系的结构及其发光特性进行了测试和研究.激发光谱表明,该荧光粉在393 nm呈现Eu³⁺的⁷Fo—⁵L₆特征激发,可以与用于发光二极管的近紫外芯片很好地匹配.在393 nm激发下,其发射光谱在591,612,701 nm处呈现Eu³⁺的⁵Do—⁷F₁,⁵Do—⁷F₂,⁵D₀—⁷F₄的特征发射.并且当固定Eu³⁺的浓度时,随着Bi³⁺含量的增加,发现Bi³⁺,Eu³⁺在这一体系中存在能量传递现象,系列样品发光强度大幅度提高.通过研究系列样品在不同Bi³⁺,Eu³⁺掺杂浓度下的发光性能,得出最佳样品为Mg_4.89Eu_0.1Bi_0.01SnB₂O₁₀,其积分强度达到了商用Y₂O₂S:Eu³⁺的1.1倍.     

橙红色荧光粉Ca3Y2Si3O12：Sm3+的制备及发光特性

采用高温固相法在1 400 ℃下经二次煅烧合成了橙红色荧光粉Ca₃Y_2-xSi₃O₁₂：xSm³⁺,研究了Sm³⁺离子掺杂浓度及助熔剂对荧光粉发光性能的影响。XRD结果显示,所合成的荧光粉的主晶相为Ca₃Y₂Si₃O₁₂。荧光光谱分析表明,Ca₃Y₂Si₃O₁₂：Sm³⁺硅酸盐荧光粉可以在320~500 nm范围内得到有效激发,并发射橙红光。在402 nm激发下,样品发射光谱中的主发射峰分别位于562 nm（⁴G_5/2→⁶H_5/2）、598 nm（⁴G_5/2→⁶H_7/2）和646 nm（⁴G_5/2→⁶H_9/2）,其中598 nm处峰值最大。改变Sm³⁺离子掺杂浓度发现：荧光粉发光强度先增大后减小,最佳Sm³⁺掺杂量x（Sm³⁺）为5%,浓度猝灭机理为离子间的相互作用。讨论了几种助熔剂的影响,NH₄F、CaF₂和NaCl均降低荧光粉的发光强度,只有H₃BO₃能够显著增强样品的发光,其最佳掺杂质量分数为1%。     

Sr2SiO4:Ce3+,Li+蓝紫色荧光粉发光性能的研究

以MCM-41为硅源,采用共沉淀法制备Sr_2-xSiO₄:xCe³⁺(x=0.01~0.09,步长为0.01)和Sr_1.95-ySiO₄: 0.05Ce³⁺,yLi⁺(y= 0.01~0.07,步长为0.02)蓝紫色荧光粉。Sr_2-xSiO₄:xCe³⁺的发射光谱是一个不对称的宽带,最大峰值在410 nm左右。Ce³⁺的最佳掺杂量为5%。Ce³⁺离子倾向于占据九配位的Sr(Ⅱ)格位。共掺电荷补偿剂Li⁺可以有效地提高Sr_1.95SiO₄: 0.05Ce³⁺的发光强度,其中Li⁺离子对1 100 ℃煅烧样品的发光强度的提高程度比1 000 ℃的更高,Li⁺的最佳掺杂量为y=0.05。     

Luminescent properties of KGd1−x(WO4)2:Eux and KGd1−x(WO4)2−y(MoO4)y:Eux phosphors in UV-VUV regions

KGd_1−x(WO₄)_2−y(MoO₄)_y:Eu³⁺_x(0.1?x?0.75, y=0 and 0.2) phosphors are synthesized through traditional solid-state reaction and their luminescent properties in ultraviolet (UV) and vacuum ultraviolet (VUV) regions are investigated. Under 147 nm excitation, these phosphors show characteristic red emission with good color purity. In order to improve their emission intensity, the MoO₄²⁻ (20 wt%) is introduced into the anion of KGd_1−x(WO₄):Eu³⁺_x. The Mo⁶⁺ and Eu³⁺ co-doped KGd(WO₄)₂ phosphors show higher emission intensity in comparison with the singly Eu³⁺-doped KGd(WO₄)₂ in VUV region. The chromaticity coordination of KGd_0.45(WO₄):Eu³⁺_0.55 is (x=0.669, y=0.331), while that of KGd_0.45(WO₄)_1.8(MoO₄)_0.2:Eu³⁺_0.55 is (x=0.666, y=0.334) in VUV region.     

Dy含量对红色长余辉发光材料Sr3Al2Ｏ6:Eu2＋,Dy3＋性能的影响

采用溶胶凝胶法制备了Sr₃Al₂Ｏ₆:Eu^2＋,Dy^3＋红色长余辉发光材料,利用X射线衍射仪对材料的物相进行了分析,结果表明,1200℃下制备的样品的物相为Sr₃Al₂Ｏ₆,少量的Eu和Dy掺杂没有影响样品的相组成.采用荧光分光光度计、照度计测定了样品的发光特性.结果表明Sr₃Al₂Ｏ关键词： 红色长余辉 3Al₂Ｏ₆')" href="#">Sr₃Al₂Ｏ₆ 溶胶凝胶法     

Ce4+离子在Ca2SnO4一维结构基质中的电荷迁移光谱研究

利用高温固相反应法制备了Ca₂Sn_1-xCe_xO₄和Ca_2-ySr_ySn_1-xCe_xO₄一维结构发光体. XPS结果显示 Ca₂SnO₄拥有两种结合能分别为5277 eV和5293 关键词： 2Sn_1-xCe_xO₄')" href="#">Ca₂Sn_1-xCe_xO₄ 2-ySr_ySn_1-xCe_xO₄')" href="#">Ca_2-ySr_ySn_1-xCe_xO₄ 一维结构 电荷迁移光谱     

Luminescent properties of green- or red-emitting Eu-doped Sr3Al2O6 for LED

Eu²⁺-doped Sr₃Al₂O₆ (Sr_3−xEu_xAl₂O₆) was synthesized by a solid-state reaction under either H₂ and N₂ atmosphere or CO atmosphere. When H₂ was used as the reducing agent, the phosphor exhibited green emission under near UV excitation, while CO was used as the reducing agent, the phosphor mainly showed red emission under blue light excitation. Both emissions belong to the d-f transition of Eu²⁺ ion. The relationship between the emission wavelengths and the occupation of Eu²⁺ at different crystallographic sites was studied. The preferential substitution of Eu²⁺ into different Sr²⁺ cites at different reaction periods and the substitution rates under different atmospheres were discussed. Finally, green-emitting and red-emitting LEDs were fabricated by coating the phosphor onto near UV- or blue-emitting InGaN chips.     

Luminescence investigation of red phosphors Ca0.54Sr0.34−1.5xEu0.08Smx(MoO4)y (WO4)1−y for UV-white LED device

Ca_0.54Sr_0.34−1.5xEu_0.08Sm_x(MoO₄)_y (WO₄)_1−y red phosphors were prepared by solid-state reaction using Na⁺ as a charge compensator for light-emitting diodes (LED). The effects of Na⁺ concentration, synthesis temperature, reaction time and Eu³⁺ concentration were studied for the properties of luminescence and crystal structure of red phosphors. The results show that the optimum reaction condition is 6%, 900 °C, 2 h and 8%. The photoluminescence spectra show that red phosphors are effectively excited at 616 nm by 292, 395 and 465 nm. The wavelengths of 465 nm nicely match the widely applied emission wavelengths of blue LED chips.     

Combustion synthesis and luminescence properties of NaY1−xEux(WO4)2 phosphors

The red phosphors NaY_1−xEu_x(WO₄)₂ with different concentrations of Eu³⁺ were synthesized via the combustion synthesis method. As a comparison, NaEu(WO₄)₂ was prepared by the solid-state reaction method. The phase composition and optical properties of as-synthesized samples were studied by X-ray powder diffraction and photoluminescence spectra. The results show that the red light emission intensity of the combustion synthesized samples under 394 nm excitation increases with increase in Eu³⁺ concentrations and calcination temperatures. Without Y ions doping, the emission spectra intensity of the NaEu(WO₄)₂ phosphor prepared by the combustion method fired at 900 °C is higher than that prepared by the solid-state reaction at 1100 °C. NaEu(WO₄)₂ phosphor synthesized by the combustion method at 1100 °C exhibits the strongest red emission under 394 nm excitation and appropriate CIE chromaticity coordinates (x=0.64, y=0.33) close to the NTSC standard value. Thus, its excellent luminescence properties make it a promising phosphor for near UV InGaN chip-based red-emitting LED application.     

Luminescent properties of HTP AgGd1−xW2O8:Eux and AgGd1−x(W1−yMoy)2O8:Eux phosphor for white LED

Intense red phosphors, AgGd_1−xEu_x(W_1−yMo_y)₂O₈ (x=0.0-1.0, y=0.0-1.0), have been synthesized through traditional solid-state reaction and characterized by X-ray diffraction (XRD) and photoluminescence (PL). XRD results reveal that AgGd_1−xEu_xW₂O₈ synthesized at 1000 °C has a tetragonal crystal structure, which is named as high temperature phase (HTP) AgGdW₂O₈. All phosphors compositions with Eu³⁺ show red and green emission on excitation either in the charge-transfer or Eu³⁺ levels. Analysis of the emission spectra with different Eu³⁺ concentrations reveal that the optimum dopant concentration for Eu³⁺ is x=0.6 in the HTP AgGd_1−xEu_xW₂O₈ (x=0.0-1.0). Studies on the AgGd_0.4Eu_0.6(W_1−yMo_y)₂O₈ (y=0.0-1.0) and AgGd_1−xEu_x(W_0.7Mo_0.3)₂O₈ (x=0.0-1.0) show that the emission intensity is maximum for compositions with y=0.3 and x=0.5, respectively, and a decrease in emission intensity is observed for higher y or x values. The Mo⁶⁺ and Eu³⁺ co-doped AgGd(WO₄)₂ phosphors show higher emission intensity in comparison with the singly Eu³⁺-doped AgGd(WO₄)₂ in UV region. The intense emission of the tungstate/molybdate phosphors under 394 and 465 nm excitations, respectively, suggests that these materials are promising candidates as red-emitting phosphors for near-UV/blue GaN-based white LED for white light generation.     

Eu3+掺杂的Sr2CeO4发光材料的光致发光研究

利用高温固相反应法制备了Eu³⁺掺杂的Sr₂CeO₄样品,并对其吸附水前后的光谱特性进行了研究.结果发现,对于刚制备的Sr_2-xEu_xCeO_4+x/2样品, 在Ce⁴⁺—O^2-的电荷迁移激发中,只有强激发带(～35700cm^-1)与Eu³⁺离子间存在能量传递,而弱激发带 (～29400cm^-1)只是引起Ce⁴⁺—O^2-的电荷迁移发射;在Sr_2-xEu_xCeO_4+x/2样品吸附水后,Eu³⁺的线状吸收跃迁强度显著增加, Ce⁴⁺—O^2-两个激发带均向Eu³⁺离子传递能量. Ce⁴⁺—O^2-强激发带通过交换作用向Eu³⁺离子传递能量,而弱激发带与Eu³⁺离子间的能量传递机理是非辐射多极子近场力的相互作用. 关键词： 2-xEu_xCeO_4+x/2')" href="#">Sr_2-xEu_xCeO_4+x/2 发光性质 能量传递 吸附水     

A red oxide phosphor, Sr2ScAlO5:Eu2+ with perovskite-type structure, for white light-emitting diodes

Sr2ScAlO5:Eu2+,a red oxide phosphor with a perovskite-type structure,has been synthesized through a solid-state reaction and its luminescence properties have been investigated.An absorption band centering at 450 nm is observed from the diffuse reflection spectra and the excitation spectra,indicating that the phosphor can match perfectly with the blue light of InGaN light-emitting diodes.A broad red emission band at 620 nm is found from the emission spectra,originating from the 4f 6 5d-4f 7 transition of the Eu 2+ ions.The best doping content of Eu in this material is about 5%.Sr2ScAlO5:Eu2+is a highly promising red phosphor for use in white light-emitting diodes.     

Photoluminescence properties of Sr1-xSi2O2N2: Eux as green to yellow-emitting phosphor for blue pumped white LEDs

This study evaluated potential applications of green to yellow-emitting phosphors (Sr_1−xSi₂O₂N₂: Eu²⁺_x) in blue pumped white light emitting diodes. Sr_1-xSi₂O₂N₂: Eu²⁺_x was synthesized at different Eu²⁺ doping concentrations at 1450 °C for 5 h under a reducing nitrogen atmosphere containing 5% H₂ using a conventional solid reaction method. The X-ray diffraction patterns of the prepared phosphor (Sr_1-xSi₂O₂N₂: Eu²⁺_x) were indexed to the SrSi₂O₂N₂ phase and an unknown intermediate phase. The photoluminescence properties of these phosphors (Sr_1−xSi₂O₂N₂: Eu²⁺_x) showed that the samples were excited from the UV to visible region due to the strong crystal field splitting of the Eu²⁺ ion. The emission spectra under excitation of 450 nm showed a bright color at 545-561 nm. The emission intensity increased gradually with increasing Eu²⁺ doping concentration ratio from 0.05 to 0.15. However, the emission intensity decreased suddenly when the Eu²⁺ concentration ratio was >0.2. As the doping concentration of Eu²⁺ was increased, there was a red shift in the continuous emission peak. These results suggest that Sr_1-xSi₂O₂N₂: Eu₂⁺_x phosphor can be used in blue-pumped white light emitting diodes.