白光LED用LiBaBO3:Eu2+材料发光特性研究

采用高温固相法制备了LiBaBO₃:Eu²⁺绿色发光材料.测量了Eu²⁺浓度为1mol%时样品的激发与发射光谱,其发射光谱为双峰宽谱,主峰分别为482和507nm,与理论计算值符合很好;监测482nm发射峰时,对应激发光谱的峰值为287和365nm,监测507nm发射峰时,对应的激发峰为365和405nm.研究了Eu²⁺浓度对材料发射光谱的影响,结果显示,随Eu²⁺浓度的增大,蓝、绿发射峰均发生了     

用于白光LED的高亮度蓝白色荧光粉Ca2SiO3Cl2：Eu2+的发光性质

采用固相法在较低温度下合成了Eu²⁺激活的Ca₂SiO₃Cl₂高亮度蓝白色发光材料,并对其发光性质进行了研究。其发射光谱由两个谱带组成,峰值分别位于420,498nm处,归结为Ca₂SiO₃Cl₂晶体中占据两种不同Ca²⁺格位的Eu²⁺离子的5d→4f跃迁发射。改变Eu²⁺浓度,可以使样品的发光在蓝白色和绿白色之间变化。当Eu²⁺浓度为0.005mol^-1时,样品呈现很亮的蓝白色发光。两个发射峰的激发光谱均分布在250~410nm的波长范围内,峰值分别位于333,369nm处。Ca₂SiO₃Cl₂:Eu²⁺可被InGaN管芯产生的近紫外辐射有效激发,是一种性能良好的白光LED用单一基质蓝白色荧光粉。     

Eu2+,Mn2+在BaZnP2O7中的发光及Eu2+→Mn2+能量传递

采用高温固相法合成了BaZnP₂O₇:Eu²⁺,Mn²⁺荧光粉，并对其发光性质及Eu²⁺对Mn²⁺的能量传递机理进行了研究.Eu²⁺和Mn²⁺在380 nm和670nm的发射峰分别由Eu²⁺的5d—4f跃迁和Mn²⁺的⁴T₁(^{4相似文献}   

Eu3+掺杂CaWO4红色荧光粉发光性质的浓度依赖关系研究

采用共沉淀法制备了不同Eu³⁺掺杂浓度的CaWO₄荧光粉材料.通过X射线衍射和场发射扫描电镜技术对样品的结构和形貌进行了表征.测量了各样品的激发光谱、发射光谱和荧光衰减曲线, 计算了各样品的部分Judd-Oflet (J-O)参数和^5D_0 (Eu³⁺)能级量子效率,以及荧光粉的色坐标, 讨论了样品电荷迁移带相对强度、J-O参数、量子效率与掺杂浓度的依赖关系.对Eu³⁺掺杂的CaWO₄ 发光材料的光致发光性质的研究表明,在CaWO₄: Eu³⁺中⁵D₀→⁷F₂跃迁的616~nm 红色发光能被394.5~nm和465~nm的激发光有效激发,具有近紫外(或蓝光)激发效率高和猝灭浓度大的优点, 有潜力成为高效的近紫外(或蓝光)激发白光发光二极管用红色荧光粉材料.     

节能灯用BaMgAl10O17:Eu2+,Mn2+荧光粉的劣化机理研究

对节能灯用BaMgAl₁₀O₁₇: Eu²⁺,Mn²⁺荧光粉的热劣化和紫外辐照劣化机理进行了对比研究. 发现热处理和紫外辐照处理均对BaMgAl₁₀O₁₇: Eu²⁺,Mn²⁺产生明显的发光劣化作用. 研究结果表明：热劣化主要涉及到Eu²⁺ 的氧化及其格位偏移, 而紫外辐照劣化与上述过程无关. 紫外辐照劣化主要源自高能紫外辐照使Eu²⁺ 处于更加不稳定的状态, 从而降低Eu²⁺ 的直接吸收和发射强度.     

用于白光LED的单一基质白光荧光粉Ca2SiO3Cl2:Eu2+,Mn2+的发光性质

用高温固相法合成了Eu2+,Mn2+共激活的Ca2SiO3Cl2高亮度白色发光材料,并对其发光性质进行了研究.该荧光粉在近紫外光激发下发出强的白色荧光,Eu2+中心形成峰值为419 nm和498 nm的特征宽带,通过Eu2+中心向Mn2+中心的能量传递导致了峰值为578 nm的发射,三个谱带叠加从而在单一基质中得到了白光.激发光谱均分布在250-415 nm的波长范围,红绿蓝三个发射带的激发谱峰值分别位于385 nm,412 nm,370 nm和396 nm处,可以被InGaN管芯产生的紫外辐射有效激发.Ca2SiO3Cl2:Eu2+,Mn2+是一种很有前途的单一基质白光LED荧光粉.     

Eu2+, Cr3+共掺杂的MAl12O19 (M=Ca, Sr, Ba) 的发光性质及能量传递

三基色荧光粉中, 红色荧光粉性能较差, 为获得性能优良的红色荧光粉, 本文采用高温固相法合成了Eu²⁺, Cr³⁺单掺杂及共掺杂的碱土金属多铝酸盐MAl₁₂O₁₉ (M =Ca, Sr, Ba) 发光体. 实验表明, 在以上三种基质中均存在Eu²⁺→Cr³⁺的能量传递, 利用能量传递可以有效将Eu²⁺的蓝光或绿光转换为红光. 三种碱土金属多铝酸盐基质的晶体结构相似,但Eu²⁺, Cr³⁺发光受晶体场影响,导致在不同的基质中Eu²⁺, Cr³⁺间能量传递效率不同.通过光谱分析及能量传递效率计算发现, 相同掺杂浓度下,CaAl₁₂O₁₉中Eu²⁺→Cr³⁺的能量传递效率最高,SrAl₁₂O₁₉次之, BaAl₁₂O₁₉最低.红光转换率在CaAl₁₂O₁₉中最高.     

退火温度对ZrO2纳米材料中Eu3+离子发光的影响

研究了退火温度对ZrO₂纳米材料中Eu³⁺离子发光性质的影响. 材料的结构、晶粒尺寸和形状以及晶格的排列分别由XRD，TEM表征. 结果表明：用共沉淀法制备的ZrO₂纳米材料具有不随退火温度变化、稳定的四方结构；材料的晶粒尺寸随退火温度的提高而增大；晶格的排列由无序逐渐变为有序；发射光谱表明其主要发射在595 nm和604 nm处；在394 nm的紫外光辐照下得到了不同样品的604 nm荧光发射强度的变化不同. 这种现象与样品中O^2-离子含量和样品表面的表面缺陷有关；另外，电荷迁移带随退火温度的变化而变化.     

白光LED用LiSrBO3∶Sm3+材料的光谱特性

采用固相法制备了一种新型的白光LED用LiSrBO₃∶Sm³⁺红色发光材料,并研究了材料的光谱特性.材料的激发与发射光谱显示其能够被404 nm近紫外光激发,发射599 nm红光,很好的符合近紫外光激发下白光LED的需要.研究了Sm³⁺浓度对材料发射强度的影响,发现Sm³⁺浓度为3 mol%时,强度最大.添加Na⁺或K⁺也可提高LiSrBO₃∶Sm³⁺材料的发射强度.     

YBO3:Eu3+纳米晶发光特性

用水热法制备了YBO₃:Eu³⁺纳米材料，通过改变其反应条件对纳米颗粒的大小和形貌进行了控制，对其发射光谱进行分析并与体材料进行了比较.在纳米材料中，很大比例的稀土离子微观环境受到表面的影响.这种影响可能使稀土离子的Judd-Ofelt参数Ω₂增大，从而使Eu³⁺的⁵D₀→⁷F₂的发射加强，红色发光材料的色纯度提高.     

Eu2+激活的Ca3SiO5绿色荧光粉的制备和发光特性研究

研究了Eu²⁺激活的绿色发光材料Ca₃SiO₅的制备条件和发光性质. Eu²⁺中心形成主峰值为501 nm和次峰值为570 nm的特征宽带，两峰值叠加形成发射峰值为502nm的绿色发射光谱带. 利用这些光谱结果和Van Uitert 经验公式，确认Ca₃SiO₅:Eu²⁺中存在两种性质有差异的Eu²⁺发光中心，它们分别占据基质中八配位的Ca²⁺(Ⅰ)格位和四配位的Ca²⁺(Ⅱ)格位. 其激发光谱分布在250—450 nm的波长范围，峰值位于375 nm处，可以被InGaN管芯产生的350—410 nm辐射有效激发. 关键词： 发光 荧光粉 绿色荧光粉 3SiO₅')" href="#">Ca₃SiO₅ 2+')" href="#">Eu²⁺     

Luminescence characteristics of Eu2+ activated Ca2SiO4 Sr2SiO4 and Ba2SiO4 phosphorsfor white LEDs

<正>This paper investigates the luminescence characteristics of Eu²⁺ activated Ca₂SiO₄,Sr₂SiO₄ and Ba₂SiO₄ phosphors. Two emission bands are assigned to the f-d transitions of Eu²⁺ ions doped into two different cation sites in host lattices,and show different emission colour variation caused by substituting M²⁺ cations for smaller cations.This behaviour is discussed in terms of two competing factors of the crystal field strength and covalence.These phosphors with maximum excitation of around 370 nm can be applied as a colour-tunable phosphor for light-emitting diodes（LEDs） based on ultraviolet chip/phosphor technology.     

Luminescence characteristics of Eu3+ activated borate phosphor for white light emitting diode

In this paper, the Sr₃Y₂ (BO₃)₄:Eu³⁺ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613nm corresponding to the electric dipole ⁵D₀--⁷F₂ transition of Eu³⁺ under 365nm excitation, this is because Eu³⁺ substituted for Y³⁺ occupied the non-centrosymmetric position in the crystal structure of Sr₃Y₂ (BO₃)₄. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet (254nm, 365nm and 400nm) and blue (470nm) light. The effect of Eu³⁺ concentration on the red emission of Sr₃Y₂ (BO₃)₄:Eu³⁺ was measured, the result shows that the emission intensities increase with increasing Eu³⁺ concentration, then decrease. The Commission Internationale del'Eclairage chromaticity (x, y) of Sr₃Y₂(BO₃)₄:Eu³⁺ phosphor is (0.640,0.355) at 15 mol% Eu³⁺.     

A novel yellow emitting phosphor Dy3+, Bi3+ co-doped YVO4 potentially for white light emitting diodes

Novel Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) phosphors for light emitting diode(LED) were successfully synthesised by solid-state reaction.The calculation results of electronic structure show that YVO4 has a direct band gap with 3 eV at G.The top of the valence band is dominated by O 2p state and the bottom of the conduction band is mainly composed of O 2p and V 3d states.An efficient yellow emission under near-ultraviolet(365 nm) excitation is observed.Compared with the pure YVO4:Dy3+ samples,the Dy3+,Bi3+ co-doped samples show a more intensive emission peak(at 574 nm) and a new broad emission band(450-770 nm),due to the 4F9/2 6H13/2 transition of Dy3+ and the emission of the VO3 4 Bi3+ complex respectively.The optimum chromaticity index of Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) is(0.447,0.497),which indicates that YVO4:Dy3+,Bi3+ has higher colour saturation than the commercial phosphor YAG:Ce3+.The effects of concentration of Dy3+,Bi3+,electric states and the photoluminescence properties are discussed in details.     

Structure and luminescence of Ca2Si5N8：Eu^2＋ phosphor for warm white light-emitting diodes

We have synthesized Ca 2 Si 5 N 8:Eu 2+ phosphor through a solid-state reaction and investigated its structural and luminescent properties.Our Rietveld refinement of the crystal structure of Ca 1.9 Eu 0.1 Si 5 N 8 reveals that Eu atoms substituting for Ca atoms occupy two crystallographic positions.Between 10 K and 300 K,Ca 2 Si 5 N 8:Eu 2+ phosphor shows a broad red emission band centred at ～1.97 eV-2.01 eV.The gravity centre of the excitation band is located at 3.0 eV-3.31 eV.The centroid shift of the 5d levels of Eu 2+ is determined to be ～1.17 eV,and the red-shift of the lowest absorption band to be ～ 0.54 eV due to the crystal field splitting.We have analysed the temperature dependence of PL by using a configuration coordinate model.The Huang-Rhys parameter S=6.0,the phonon energy ν=52 meV,and the Stokes shift S=0.57 eV are obtained.The emission intensity maximum occurring at ～200 K can be explained by a trapping effect.Both photoluminescence (PL) emission intensity and decay time decrease with temperature increasing beyond 200 K due to the non-radiative process.     

Dy3+、Tm3+共掺杂Ca2MgSi2O7的发光特性

采用高温固相法合成了系列Ca₂MgSi₂O₇：Dy³⁺,Tm³⁺发光材料。对样品进行了XRD结构表征,测量了激发光谱、发射光谱、色温和荧光寿命。研究结果表明,Ca₂MgSi₂O₇：Tm³⁺在355 nm激发下显示出蓝色发光,在CIE1931中的色坐标为x=0.165 9,y=0.082 2,色纯度为89%。通过Dy³⁺和Tm³⁺的叠加激发谱带激发,即在349,353,365 nm激发下,Ca₂MgSi₂O₇：Dy³⁺,Tm³⁺显示出青白、冷白和暖白光,相关色温值分别为5 193,9 672,4 685 K。300~500 nm区域间可以有效地激发Ca₂MgSi₂O₇：Dy³⁺,Tm³⁺,并在400~600 nm之间产生蓝光和黄光复合产生的白光,表明该体系可用作白光LED的发光材料。     

TiO2微粒对远程荧光粉膜及白光发光二极管器件光色性能的影响

利用热压法将TiO₂微粒掺入至YAG:Ce荧光粉和硅树脂中制备出远程荧光粉膜并封装成白光发光二极管(LED)器件, 通过荧光粉相对亮度仪、双积分球测试系统和可见光光谱分析系统对样品的光色性能及机理进行了研究. 结果表明: TiO₂的散射效应能够显著提高蓝光的利用率和黄光的透射强度, 白光LED器件的光通量在TiO₂浓度为0.966 g/cm³ 时达到最高值415.28 lm(@300 mA, 9.3 V), 提高了8.15%, 相关色温从冷白6900 K逐渐变化至暖白3832 K. TiO₂的掺入不仅提高了远程荧光粉膜的发射强度和白光LED器件的光通量, 同时能调控其相关色温.