Aqueous Synthesis of Water-Soluble Citrate-Modified Cadmium Selenide/Cadmium Sulfide/Zinc Sulfide Quantum Dots

Water-soluble cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots were synthesized in aqueous solution using trisodium citrate as modifier. The crystal structure, morphology, component, and spectral properties of cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots were characterized by X-ray power diffraction, transmission electron microscope, energy dispersive X-ray analysis, infrared spectrum, ultraviolet–visible absorption spectrum, and fluorescence spectrum. The results show that the spherical citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots with diameter around 3.6 nm belong to the cubic zinc blende structure. The citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots show a narrow, symmetric, and strong fluorescence emission spectrum band with narrow full width at half maximum of 53 nm, and the fluorescence quantum yield can reach up to 37.3%. The high-quality citrate-modified cadmium selenide/cadmium sulfide/zinc sulfide core/shell/shell quantum dots with good fluorescence properties have potential for application in biological fluorescence analysis.     

核-壳结构ZnS:Tb/CdS纳米晶的电致发光

利用微乳液方法合成出粒径为4nm的核．壳结构ZnS：Tb／CdS纳米晶。用XRD、TEM及荧光光谱等手段对合成的纳米晶的结构、形态和光学特性分别进行了表征。将ZnS：Tb／CdS纳米晶制作成有机-无机杂化结构电致发光器件,其结构为ITO／poly（3,4-ethylene dioxythiophene）：poly（styrene sulfonate）（PEDOT-PSS）（70nm）／poly（vinyleobarzale）（PVK）（100nm）／ZnS：Tb／CdS纳米晶（120nm）／2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline（BCP）（30nm）／LiF（1．0nm）／Al（100nm）。当驱动电压为13V时,可以测到Tb^3＋离子的两个特征峰。在电致发光光谱中未测到聚合物PVK的发光,说明电子和空穴是在纳米晶层上复合的。当驱动电压为25V时,得到器件的最大亮度为19cd／m^2。     

核/壳结构ZnS : Mn/CdS纳米粒子的制备及发光

利用溶剂热法制备了Mn离子掺杂的ZnS纳米粒子(ZnS : Mn),利用沉淀法对ZnS ∶ Mn纳米粒子进行了不同厚度的CdS无机壳层包覆。采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及光致发光(PL)光谱等手段对样品进行了表征。TEM显示粒子为球形,直径大约在14~18 nm之间。由XRD结果可以看出CdS壳层的形成过程受到了ZnS ∶ Mn核的影响,导致其结晶较差。XRD和XPS测量证明了ZnS : Mn/CdS的核壳结构。随着CdS壳层的增厚,样品的发光强度呈现一直减弱的现象。     

HgTe/CdS/ZnS多壳层量子点的制备与表征

采用一种简单的方法合成HgTe/CdS/ZnS多壳层量子点。首先,以1-硫代甘油为稳定剂,在水相溶液中制备出HgTe核量子点;然后,采用外延生长法依次在HgTe核量子点表面包覆CdS和ZnS壳层,合成出最终具有稳定近红外发光的HgTe/CdS/ZnS多壳层量子点。该合成方法仅需3个步骤,具有操作简单、成本低廉的优点。实验结果显示,当反应温度为90 ℃、反应溶液pH为11.0、反应加热回流时间为4 min时,HgTe/CdS/ZnS多壳层量子点具有最高荧光量子产率36%。     

Selective Synthesis of Wurtzite CdSe Nanorods and Zinc Blend CdSe Nanocrystals through a Convenient Solvothermal Route

By simply changing the reactants’ compositions, wurtzite CdSe nanorods and zinc blend CdSe nanoparticles were selectively synthesized through a convenient solvothermal route with the reaction of cadmium nitrate (Cd(NO₃)₂· 4H₂O), hydrazine hydrate (N₂H₄· H₂O), and Se in ethylenediamine (en) at 140°C. Effects of temperature and composition of the reactants were detected and the amount and gaining rate of Se²⁻ ions were found to determine the morphology and structure of the final product. Dong Wu and Guo-Qiao Lai contributed equally to this paper     

核/壳结构的ZnS:Mn/SiO_2纳米粒子的制备及发光性质研究

采用溶剂热法制备了Mn离子掺杂的ZnS纳米粒子(ZnS∶Mn),然后利用正硅酸乙酯(TEOS)的水解反应对其进行了不同厚度的SiO2无机壳层包覆。采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及荧光发射光谱(PL)对样品的结构及光学性质进行了表征和研究。包覆SiO2壳层后,粒子的粒径明显增大并且在ZnS∶Mn纳米粒子表面可以观察到明显的SiO2壳层。XPS测试印证了ZnS∶Mn/SiO2的核壳结构。随着SiO2壳层的增厚,ZnS∶Mn/SiO2的Mn离子的发光先增强后减弱,这是因为SiO2壳层同时具有表面修饰和降低发光中心浓度这两种相反的作用。当壳层厚度(壳与核的物质的量的比)达到5时,发光效果达到最好,其强度达到未包覆样品的7.5倍。     

ZnS:Mn纳米荧光粉的制备

介绍一种制备ZnS:Mn纳米荧光粉的化学合成方法。本合成通过调节甲基丙烯酸与巯基乙酸的摩尔比，可在1.8-3nm范围内对纳米粒径进行很好的控制。生成的聚甲基丙烯酸包敷了ZnS:Mn纳米微粒，从而防止了纳米微粒团聚，同时增强了纳米微粒的抗氧化性，大大提高了纳米荧光粉的发光效率和发光稳定性。通过透射电镜（TEM）、X射线粉末衍射（XRD）和光致发光谱（PL）对所制得的纳米粉末进行了表征。     

复合空心立方银/金属纳米材料的制备及其SERS表征

本文用一锅法, 以立方银纳米材料为模板, 通过置换反应成功制备了空心的立方银/钯(Ag/Pd)、银/铂(Ag/Pt)和银/金(Ag/Au)纳米材料, 并将它们作为基底(以KSCN作为探针), 检测其SERS信号。     

Novel Two-Step Approach for the Synthesis of Cadmium Selenide/Zinc Sulfide Core/Shell Nanocomposites with Precursor Injection Technique

This work describes the synthesis of cadmium selenide/zinc sulfide core/shell nanoparticles from the cadmium oxide precursor through a convenient, two-step approach. This modified novel synthesis procedure for cadmium selenide/zinc sulfide nanoparticles in trioctylphosphine oxide and trioctyl phosphine provides better control over growth dynamics. The outer zinc sulfide shell provides efficient confinement of electron and hole wave functions inside the nanocrystals as well as high photochemical stability. The materials have been characterized using a range of optical and structural techniques. The high resolution transmission electron microscope micrographs of the cadmium selenide/zinc sulfide core/shell nanoparticles show well-defined spherical particles with an increase in diameter as compared to the parent cadmium selenide material. Thus, the present simulation and its extension can give insight to the understanding of the formation of core/shell or other heterostructures in different kinds of self-assembled aggregates.     

采用紫外光照法在磷酸盐玻璃中合成CdS/Ag复合微粒

掺杂有Ⅱ-Ⅵ族半导体纳米颗粒(如CdS)或者过渡金属(如Ag)的玻璃由于其较大的非线性光学效应而引起人们的极大兴趣,而同时掺杂有半导体/金属的复合微粒则可以进一步增强玻璃的三阶非线性效应,因此成为目前的研究热点。我们利用玻璃沉淀技术及随后的热处理和紫外光还原技术制备了含高浓度(1%)Ag微粒的玻璃,并采用X射线衍射分析了其物相,用高分辨扫描电镜分析了其形貌,以及测试了其吸收和发光性能。从CdS/Ag复合微粒的扫描照片可以发现晶粒均匀分布在玻璃中,尺寸约为1μm。X射线衍射发现经过热处理和紫外光照的样品衍射峰中含有CdS和Ag,而只进行热处理的样品则只含有CdS,未处理的样品则显非晶态。CdS/Ag复合微粒的吸收峰呈现典型的表面等离子共振峰(420nm)以及CdS的峰(600nm),只含有CdS微粒的样品的吸收峰则在480nm附近,未处理的样品在320nm附近有一个吸收峰,这可能是由于样品在快速冷却过程中的微小晶化造成的。只含有CdS微粒的样品有三个明显的发光峰,然而CdS/Ag复合微粒的发过峰则消失。我们提出了共振能量转移机制来解释该现象。讨论了紫外光照还原Ag微粒的机制。可以认为通过紫外光照,CdS表面的电子被激发出来还原Ag+,从而形成银颗粒,伴随着空穴则被表面缺陷所捕获。     

单核/双壳结构CdSe/CdS/ZnS纳米晶的合成与发光性质

以巯基乙酸为稳定剂,在水溶液中合成了单核/双壳结构的CdSe/CdS/ZnS纳米晶。在内核CdSe和外壳ZnS之间的内壳CdS作为晶格匹配调节层,能够很好的改善核/壳界面处的性能,而且,最外层ZnS能够最大程度地使激子受限。用TEM和XPS对纳米晶进行了表征,并且用光致发光光谱和吸收光谱对不同核壳结构的纳米晶的发光性能进行了比较,结果表明单核/双壳结构的纳米晶具有更加优异的发光特性。     

Silver-Alkylamine Complex Mediated Single Micelle toward Synthesis of Sub-8 nm Silver Nanocrystals

Small size and narrow distribution are the key factors to improve performances of metal nanocrystals due to nanosize effect. Here, a silver-alkylamine complex–mediated single micelle, a one-pot approach, for controlled synthesis of monodisperse silver nanocrystals, in which oleylamine molecules play key roles serving both as complex agent and as micellar coalescence blocker is reported. After the synthesis, monodisperse products can be directly collected through subsequent single-step separation as the particle size is finely adjusted during the synthesis. Dual-soluble silver oleylamine complex is prepared through liquid phase complexing and is used as oil-soluble precursor in single reverse micelle. The as-synthesized silver nanocrystals are very uniform with a controlled size of 6.00 ± 0.29 or 8.0 ± 0.40 nm and a narrow size distribution with a standard deviation (σ) of ≈5.0%. The protocol offers a general platform for fast synthesis of noble metal nanocrystals with rationally designed size and structure.     

Mn2+, Pb2+共掺杂ZnS纳米材料制备及光致发光

采用聚乙烯基吡咯烷酮(PVP)为表面包覆剂,在室温大气条件下的水溶液中制备了ZnS:Mn,Pb纳米晶。讨论了Mn²⁺和Pb²⁺掺杂量对ZnS纳米发光材料光致发光强度的影响,确定了Mn²⁺和Pb²⁺掺杂量相对于Zn²⁺的最佳的量的比,并对其发光机理进行了初步的探讨。     

Synthesis and Optical Properties of Eu3+ Ion Doped Nanocrystalline Hydroxyapatites

The Ca₁₀(PO₄)₆(OH)₂ hydroxyapatite (HA) nanopowders doped with Eu³⁺ ions were prepared using a wet synthesis method. Their structure and morphology were investigated. The XRD analysis has proven a single-phase of HA nanocrystallites. The average sizes of HA nanocrystallites calcinated at 400°C and 700°C were determined to be about 20 nm and 30 nm, respectively. The emission and excitation spectra as well as the fluorescence decay rates of Eu³⁺ ion doped HA nanocrystallites were measured. Particular attention was given to the spectroscopic properties of Eu³⁺ ions as a luminescent probe of nanocrystalline HA structure as a result of varying annealing temperature and dopant concentration. The Judd-Ofelt analysis of f-f transitions of Eu³⁺:HA nanocrystallites was performed. The effect of calcination temperatures on grain sizes and luminescence properties is noted and discussed.     

弯曲银/银同质结纳米线的合成及其SERS表征

用液相法合成弯曲的银/银(Ag/Ag)同质结纳米线, 即由Ag/Ag同质结和Ag纳米棒组成。同质结相邻的两个Ag纳米棒以一定的角度形成弯曲的Ag纳米线, 其角度可能是锐角, 也可能是钝角, 而且其长度可达几个微米。研究发现, 反应温度对弯曲Ag/Ag同质结纳米线的形成具有非常重要的作用, 改变反应温度, 得到的是其它形状的纳米粒子; 同时, 表面增强拉曼光谱(SERS)表征发现, 与Ag纳米球和纳米线相比, 弯曲Ag/Ag同质结纳米线具有更好的SERS活性。     

L-半胱氨酸修饰CdS量子点检测银离子

室温一步合成了L-半胱氨酸修饰的CdS量子点,具有水溶性和生物相溶性。在0．0050mol／L磷酸缓冲溶液中,于L-半胱氨酸存在下,银离子对CdS量子点荧光发射有显著的增敏作用,CdS量子点荧光发射峰位置逐渐由545nm向558nm红移,CdS量子点荧光强度与银离子的浓度成线性关系,方法的线性响应范围为2．0×10^-7-1．0×10^-6mol／L,检出限为2．1×10^-8mol／L。是一种简单,迅速,灵敏且可操作的检测银离子的新方法。