双钙钛矿型Ca2Gd1-xTaO6：xTb3+绿色荧光粉的合成与荧光性质

通过高温固相法合成了双钙钛矿型Ca₂Gd_1-xTaO₆：xTb³⁺（CGTO：xTb³⁺）绿色荧光粉。采用X射线衍射、扫描电镜、荧光光谱、荧光衰减曲线、量子效率（η）测试分别表征了CGTO： xTb³⁺荧光粉的物相、形貌和荧光性质。在紫外光激发下,CGTO： xTb³⁺荧光粉实现了较强的绿光发射,绿光为Tb³⁺离子的⁵D₄-⁷F₅跃迁。通过变温发射光谱研究发现CGTO：0.15Tb³⁺荧光粉的热猝灭活化能为0.181 9 eV。在255 nm的激发下,最佳Tb³⁺掺杂浓度的CGTO：0.15Tb³⁺荧光粉的量子效率为32.32%。     

Ca0.8-2x(YbxTb0.1Na0.1+x)2xWO4近红外下转换荧光粉水热合成及发光性质

一种在近红外光谱(NIR)区域高效的量子剪裁现象已在Ca0.8-2x(Ybx Tb0.1Na0.1+x)2x WO4(x=0～0.2)荧光粉中得到证实,该量子剪裁通过吸收紫外线光子发射近红外光子,能量传递包括两个协同过程,分别是WO42-基团到Yb3+离子和WO42-基团到Tb3+离子再到Yb3+离子,Yb3+离子的掺杂浓度对荧光粉在可见光和近红外光谱的发光,荧光寿命和量子效率的影响已进行了详细的研究。经计算,量子效率最大达到135.7%。铽与镱共掺钨酸钙的近红外量子剪裁,通过吸收太阳光谱的1个紫外光子到2个1 000 nm光子(2倍光子数增加)的下转化机制实现高效率硅太阳能电池的途径。     

LiBa0.95-yBO3:0.05Tb3+,yBi3+荧光粉的制备及荧光性质

以硼酸和碳酸盐为原料,用高温固相法制备了可被（近）紫外光（369、254 nm）有效激发的Tb³⁺单掺杂LiBa_1-xBO₃：xTb³⁺（物质的量分数x=0.02、0.03、0.04、0.05、0.06、0.07）及Bi³⁺和Tb³⁺共掺杂LiBa_0.95-yBO₃：0.05Tb³⁺,yBi³⁺（物质的量分数y=0.02、0.03、0.04、0.05、0.06、0.07）的2个系列荧光粉,产物的结构和形貌分别用粉末X射线衍射（PXRD）和扫描电子显微镜进行表征。PXRD测定结果表明2个系列的产物均为纯相LiBaBO₃。通过对第一系列产物荧光光谱的测定,筛选出发光强度最好的产物,据此确定铽离子的最佳掺杂量;在此基础上制备出铋离子掺杂量不同的第二系列荧光粉。荧光光谱测定的实验结果表明,Tb³⁺/Bi³⁺共掺杂的荧光粉的发光强度好于Tb³⁺单掺杂的荧光粉,这说明Bi³⁺对Tb³⁺有敏化作用;而且随着Bi³⁺掺杂量的增加,产物的荧光强度表现出先增加后减小的趋势,当Bi³⁺的掺杂量y=0.03时,产物的荧光强度达到最大。Bi³⁺和Tb³⁺之间存在偶极-四极相互作用而进行能量传递。系列荧光粉的CIE坐标显示其发光颜色在一定程度上呈现出由绿色光到白光的渐变趋势。     

Bi2WO6量子点(QDs)修饰Bi2MoO6-xF2x异质结的构筑及其催化活性增强机理

采用简单沉积-沉淀法合成了Bi₂WO₆@Bi₂MoO_6-xF_2x（BWO/BMO6-xF2x）异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B（RhB）的光催化降解作为探针反应来评价Bi₂WO₆@Bi₂MoO_6-xF_2x异质结的光催化活性增强机制。形貌分析表明,所得Bi₂MoO₆微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi₂WO₆量子点均匀沉积在Bi₂MoO_6-xF_2x微球表面,形成新颖的Bi₂WO₆@Bi₂MoO_6-xF_2x异质结;与纯Bi₂MoO₆或者Bi₂WO₆相比,1∶1Bi₂WO₆@Bi₂MoO_6-xF_2x异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi₂WO₆量子点表面沉积显著提高Bi₂MoO_6-xF_2x光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O₂^-和h⁺是主要的活性物种。根据实验结果,探讨了F^-掺杂和Bi₂WO₆量子点之间的协同效应对Bi₂MoO₆的光催化活性的影响机制。     

微乳液法合成白光LED NaLu(MO4)2:Eu3+/Eu3+,Tb3+(M=W, Mo)荧光粉

采用微乳液法制备NaLu(WO₄)_2-x(MoO₄)x:8%Eu³⁺(x=0, 0.5, 1.0, 1.5, 2.0)/y%Eu³⁺,5%Tb³⁺(y=1, 3, 5, 7, 9)系列荧光粉.通过X射线衍射(XRD)表征,所制样品的X射线衍射峰与标准卡片PDF#27-0729基本吻合,表明所制的样品为白钨矿结构,属于四方晶系.扫描电镜SEM显示制备的纳米粒子是梭子状的,粒径大约是110 nm.激发发射光谱显示,在Eu³⁺离子掺杂浓度为8%时,NaLu(WO₄)(MoO₄):Eu³⁺发光强度最大.NaLu(WO₄)_2-x(MoO)x :8%Eu³⁺(x=0, 0.5, 1.0, 1.5, 2.0)荧光粉在Mo/W比达到1:1(x=1)时发光强度最大,强烈的红光发射表明该材料可用于白光LED材料.该荧光粉在268、394和466 nm波长光激发下分别发出橙红色、黄色和淡黄色光,可以满足不同光色需要.NaLu(WO)(MoO):y%Eu³⁺,5%Tb³⁺(y=1, 3, 5, 7, 9)荧光粉,随着y值增大,从绿光区(x=0.278, y=0.514)进入白光区(x=0.356, y=0.373), (x=0.278, y=0.313),同时观察到Tb³⁺到Eu³⁺有效能量传递.     

ErxYb1-x(TPB)3Bath(x=0,0.218,0.799,0.896,0.987,1)配合物的近红外发光性能

采用4,4,4-三氟-1-苯基-1,3-丁二酮（TPB）为第一配体,4,7-二苯基-1,10-菲咯啉（Bath）为第二配体,分别制备了配合物Er（TPB）₃Bath和Yb（TPB）₃Bath,以及它们的混合配合物Er_xYb_1-x（TPB）₃Bath（x=0.218,0.799,0.896,0.987）,并对所制得配合物的发光性能进行了系统研究。研究结果表明,所有配合物均能发射所含稀土离子的近红外特征光,并且可以通过调节混合配合物中的n_Er/n_Yb来调控Yb³⁺/Er³⁺之间的能量传递,进而提高Er³⁺离子在1530 nm处的发光。     

空气中合成固溶体荧光粉Ba2(Zn, Mg)Si2O7:Ce3+,Eu2+,Eu3+及其发光特性

采用高温固相法在空气中合成了Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu,yCe³⁺系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu²⁺离子的4f⁶5d¹-4f⁷跃迁,590~725 nm红光区窄带谱源于Eu³⁺的⁵D₀-⁷F_J (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu³⁺在Ba_1.97-yZn_1-xMg_xSi₂O₇基质中被还原成了Eu²⁺;当x=0.1时,荧光粉Ba_1.97Zn_0.9Mg_0.1Si₂O₇:0.03Eu的绿色发光最强,表明Eu³⁺被还原成Eu²⁺离子的程度最大。当共掺入Ce³⁺离子后,形成Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺荧光粉体系,其发光随着Ce³⁺离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.01Ce³⁺,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba₂Zn_0.9Mg_0.1Si₂O₇基质中的能量传递与发光机理。     

Cr3+掺杂Ca4HfGe3O12宽带近红外荧光粉的发光特性及应用

近红外荧光粉在生物活体成像领域展现出重要的应用前景。但活体成像用近红外荧光粉存在种类匮乏、耐温性差等瓶颈问题。采用固相法合成了宽带近红外Ca₄HfGe₃O₁₂∶ xCr³⁺(0≤x≤0.09)荧光粉。X射线衍射和能谱分析的结果表明Cr³⁺离子成功进入Ca₄HfGe₃O₁₂晶格。在469 nm蓝光激发下，Ca₄HfGe₃O₁₂∶xCr³⁺荧光粉发射出690~1 200 nm的宽带近红外光，峰值波长为825 nm (⁴T₂-⁴A₂)，半高宽达到141 nm，Cr³⁺掺杂最佳浓度为0.03。依据激发光谱峰形和寿命衰减行为，证实Cr³⁺仅占据基质中一种阳离子格位。Ca₄HfGe₃O₁₂∶0.03Cr³⁺荧光粉的荧光量子效率为33.63%，该荧光粉发射光谱在400 K下的积分面积为室温下的60.5%，表明该样品具有优良的热稳定性。采用自制近红外荧光粉转换器件照射人手掌和滤波片遮挡的水果，观察到清晰地静脉血管和遮挡水果的轮廓。     

Er3+，Yb3+共掺杂NaY(WO4)2上转换荧光粉的制备及其发光性能

应用传统水热法合成出具有四方白钨矿结构的NaY（WO₄）₂微米颗粒及一系列Er³⁺/Yb³⁺共掺杂NaY（WO₄）₂上转换荧光粉。利用XRD、SEM、TEM、HRTEM、粒度分布和上转换发光光谱对样品的物相、形貌及上转换发光性能进行分析表征。结果表明,pH值对于制备具有同一形貌的纯相NaY（WO₄）₂微米颗粒发挥重要作用。随着pH值的升高,可以完成从八面体到拟立方体再到片状颗粒的形貌转变。在980 nm近红外光激发下,观测到525及553 nm处的强绿光发射,对应Er³⁺的²H_11/2→⁴I_15/2与⁴S_3/2→ ⁴I_15/2跃迁,以及650~680 nm范围内的弱红光发射,对应Er³⁺的⁴F_9/2→⁴I_15/2跃迁,且绿、红光上转换发射均属于双光子过程。此外,通过调节NaY（WO₄）₂：Er³⁺,Yb³⁺荧光粉中Yb³⁺的浓度,可实现对绿光色度的有效控制。     

ErxYb1-x（TPB）3Bath（x=0，0.218，0.799，0.896，0.987，1）配合物的近红外发光性能

采用4,4,4-三氟-1-苯基-1,3-丁二酮（TPB）为第一配体,4,7-二苯基-1,10-菲咯啉（Bath）为第二配体,分别制备了配合物 Er（TPB）₃Bath和Yb（TPB）₃Bath,以及它们的混合配合物Er_xYb_1-x（TPB）₃Bath（x=0.218,0.799,0.896,0.987）,并对所制得配合物的发光性能进行了系统研究。研究结果表明,所有配合物均能发射所含稀土离子的近红外特征光,并且可以通过调节混合配合物中的 n_Er/n_Yb来调控Yb³⁺/Er³⁺之间的能量传递,进而提高Er³⁺离子在1530 nm处的发光。     

Visible quantum cutting through downconversion in GdPO4:Tb and Sr3Gd(PO4)3:Tb

Visible quantum cutting has been observed in GdPO₄:Tb³⁺ upon Tb³⁺ 4f⁸–4f⁷5d¹ excitation and host excitation, and in Sr₃Gd(PO₄)₃:Tb³⁺ upon Tb³⁺ 4f⁸–4f⁷5d¹ excitation. In the quantum cutting process, Tb³⁺ acts as a quantum cutter, which converts one short wavelength ultraviolet photon or one vacuum ultraviolet photon into more than one visible photon. The quantum cutting involves a cross-relaxation process between two neighboring Tb³⁺ and direct energy transfer between Tb³⁺ and Tb³⁺ or Tb³⁺ and Gd³⁺, depending on the excitation wavelength. The quantum efficiency variation of GdPO₄:xTb³⁺ and Sr₃Gd(PO₄)₃:xTb³⁺ shows a growing trend with increasing of Tb³⁺ content from x=1.5% to 13%.     

Effcient Near-Infrared Quantum Cutting in Tm3+/Yb3 Codoped LiYF4 Single Crystals for Solar Photovoltaic

Downconversion (DC) with emission of two near-infrared photons about 1000 nm for each blue photon absorbed was obtained in thulium (Tm³⁺) and ytterbium (Yb³ ) codoped yt-trium lithium fluoride (LiYF₄) single crystals grown by an improved Bridgman method. The luminescent properties of the crystals were measured through photoluminescence excitation, emission spectra and decay curves. Luminescence between 960 and 1050 nm from Yb³ : ²F_5/2→²F_7/2 transition, which was originated from the DC from Tm³ ions to Yb³ ions, was observed under the excitation of blue photon at 465 nm. Moreover, the energy transfer processes were studied based on the Inokuti-Hirayama model, and the results indicated that the energy transfer from Tm³ to Yb³ was an electric dipole-dipole interaction. The max-imum quantum cutting effciency approached up to 167.5% in LiYF₄ single crystal codoped with 0.49mol% Tm³ and 5.99mol% Yb³ . Application of this crystal has prospects for increasing the energy e ciency of crystalline Si solar cells by photon doubling of the high energy part of the solar spectrum     

Bi2WO6量子点(QDs)修饰Bi2MoO6-xF2x异质结的构筑及其催化活性增强机理

采用简单沉积-沉淀法合成了Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)(BWO/BMO_(6-x)F_(2x))异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B(Rh B)的光催化降解作为探针反应来评价Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结的光催化活性增强机制。形貌分析表明,所得Bi_2MoO_6微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi_2WO_6量子点均匀沉积在Bi_2MoO_(6-x)F_(2x)微球表面,形成新颖的Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结;与纯Bi_2MoO_6或者Bi_2WO_6相比,1∶1Bi_2WO_6@Bi_2MoO_(6-x)F_(2x)异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi_2WO_6量子点表面沉积显著提高Bi_2MoO_(6-x)F_(2x)光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O_2~-和h~+是主要的活性物种。根据实验结果,探讨了F-掺杂和Bi_2WO_6量子点之间的协同效应对Bi_2MoO_6的光催化活性的影响机制。     

Vacuum ultraviolet and near-infrared excited luminescence properties of Ca3(PO4)2:RE, Na (RE=Tb, Yb, Er, Tm, and Ho)

Tb³⁺, Yb³⁺, Tm³⁺, Er³⁺, and Ho³⁺ doped Ca₃(PO₄)₂ were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb³⁺-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb³⁺ content is comparable with that of the commercial Zn₂SiO₄:Mn²⁺ green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb³⁺, Tm³⁺, Er³⁺, and Ho³⁺ doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb³⁺-Ho³⁺, Yb³⁺-Er³⁺, and Yb³⁺-Tm³⁺ in Ca₃(PO₄)₂, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb³⁺-Tm³⁺-Er³⁺-Ho³⁺ in Ca₃(PO₄)₂, in which the cross-relaxation process between Er³⁺ and Tm³⁺, producing the ¹D₂-³F₄ transition of Tm³⁺, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams.     

Flame synthesized Y<Subscript>2</Subscript>O<Subscript>3</Subscript>:Tb<Superscript>3+</Superscript>–Yb<Superscript>3+</Superscript> phosphors as spectral convertors for solar cells

Near-infrared (NIR) quantum cutting phosphors serve as a potential material for fabricating photovoltaic spectral convertors. In many cases, quantum cutting phosphors are obtained via a wet chemical method coupled with a post-annealing treatment—a very costly process. In this report, we used continuous flame spray pyrolysis (FSP) for fabricating Y₂O₃:Tb³⁺–Yb³⁺ quantum-cutting phosphors without any post-treatment. Based on characterizations by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we found that as-synthesized Y₂O₃:Tb³⁺–Yb³⁺ phosphors exhibit hollow and shell-like micro-structures composed of highly crystalline and pure cubic-phase nanoparticles (< 50 nm). Photoluminescence studies of the phosphors revealed that NIR emissions appeared with the introduction of Yb to Y₂O₃:Tb³⁺. Phosphor size was successfully controlled by managing the concentration of the metal precursor solution for FSP. The Y₂O₃:Tb³⁺–Yb³⁺ phosphors were then embedded into transparent poly-ethylene-co-vinyl acetate (EVA) film to form a spectral convertor. The composite films of Y₂O₃:Tb³⁺–Yb³⁺ phosphors and poly-EVA were found to be highly transparent in the visible range (> 500 nm), making them suitable as spectral photovoltaic convertors.     

NixCo3-xO4表面修饰对CdSe/TiO2纳米管阵列光电化学氧化水活性的影响

利用氨挥发诱导法在CdSe/TiO2纳米管阵列表面负载一层NixCo3-xO4。采用SEM、XRD、XPS、UV-Vis对样品进行表征,通过线性扫描伏安法测定光阳极的释氧电势来评价其光电水氧化活性。结果表明:表面NixCo3-xO4是尖晶石结构;相对于CdSe/TiO2纳米管阵列光阳极,NixCo3-xO4/CdSe/TiO2光阳极能将光电氧化水的过电势降低430 mV。Ni离子的引入使得NixCo3-xO4表面富含三价阳离子(Ni3+,Co3+),从而促进CdSe/TiO2光阳极光电水氧化的进行。