A solution phase thermal decomposition molecule precursors route to ZnS:Cu2+ nanorods and their optical properties

ZnS:Cu²⁺ nanorods were synthesized through a solution phase thermal decomposition molecule precursor route. The absorption spectra showed a minor red shift with increasing Cu doping concentration. Photoluminescence showed red shift and the intensity of defect luminescence emission would be enhanced as the concentration of Cu ions (0.2–0.4%) increased. The optical properties of the products can be controlled easily by changing Cu doping concentration. This synthetic strategy might exploit a favourable route to synthesize metal-doped semiconductor nanostructures, which are potentially important for optoelectonic nanodevices.     

Structural,optical and magnetic properties of Cu doped CdSe powders prepared by solid state reaction method

Cu doped CdSe powders were synthesized by solid state reaction method and studied the effect of Cu doping concentration on structural, optical and magnetic properties of the prepared samples. From XRD study it was found that the lattice constant increased with increase of Cu doping concentration. A clear blue shift was observed in the samples from optical studies. From the magnetic measurements, it was found that the samples were room temperature ferromagnetic in nature and strength of magnetic moment increased with increase of doping concentration. These synthesized powders are dilute magnetic semiconductors and are very promising candidates for ‘Spintronic’ device applications.     

Morphology and microstructure of textured SnO2 thin films obtained by spray pyrolysis and their effect on electrical and optical properties

Tin dioxide thin films on glass substrate with different Zn doping levels were obtained by spray pyrolysis. Their microstructure, preferred crystallographic orientation, electrical and optical properties were extensively studied. The characterization techniques employed were scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, electrical conductivity and optical transmission measurements. It was found that the material obtained has a nano-scale texture which characteristic size and orientation strongly depend on the Zn doping level. Doping-induced variations in texture and structure modify both the electrical and optical properties of films (namely, refractive index and transparency). The results obtained are relevant for potential applications of the studied films in gas sensing and photoconductive devices.     

Ce的添加对SnAgCu系钎料组织和性能的影响

通过向Sn-0.3Ag-0.7Cu系无铅焊料中添加微量稀土Ce,研究不同稀土含量对Sn-0.3Ag-0.7Cu合金的熔化温度和润湿性的影响,同时利用扫描电子显微镜(SEM)对焊料的显微组织进行了分析.实验结果表明,添加Ce对焊料的熔化温度影响不大,但对合金的润湿性和微观组织影响较大.当ω(Ce)=0.10%时,焊料合金的综合性能较好.     

Cu掺杂ZnSe高效量子点的合成及其光学特性研究

采用生长掺杂方式制备了Cu掺杂ZnSe高效量子点, 探索了不同Zn、Se前驱体配比对ZnSe晶核以及ZnSe:Cu量子点质量的影响, 并研究了Cu离子掺杂过程中的光谱特征。研究表明, 进一步通过在表面掺杂的ZnSe:Cu量子点上同质包覆ZnSe壳层, 能够实现其发光效率和稳定性的有效提高; 采用配体交换能够实现ZnSe:Cu量子点由油溶性到水溶性的转变。这种新型的掺杂量子点有望替代传统含Cd量子点应用于环境友好型固体发光器件和生物标记。     

Synthesis and characterization of porous ZnO nanoparticles by hydrothermal treatment of as pure aqueous precursor

The presence of the complexing agents in the growth solution poses risk of the unintentional doping in the synthesized product and hence is likely to adversely affect the intrinsic properties. Herein we report the synthesis of ZnO nanoparticles with porous microstructure using pure aqueous precursor. Crystalline ZnO nanoparticles were synthesized by thermal treatment of aqueous solution of zinc acetate in an open bath. The size of the nanocrystals was controlled by changing the initial precursor concentration. The structural and optical properties of the synthesized nanocrystals were analyzed by X-ray diffraction, high resolution transmission electron microscopy, UV-vis absorption and room temperature photoluminescence measurement techniques. The TEM and UV-vis spectral signature analyses confirmed the formation of dispersed single crystalline ZnO nanoparticles. The nanopowders were found to have disordered mesoporous structure. The synthesized nanocrystals exhibited characteristic band edge emission as well as to surface defect related deep level visible luminescence.     

不同浓度Cu掺杂SnO2材料电学和力学性质的研究

为研究Cu掺入对SnO_2性能的影响,本文采用密度泛函理论和平面波赝势法,建立了未掺杂SnO_2和不同比例Cu掺杂的SnO_2晶胞模型,对Sn_(1-x)Cu_xO_2(x=0、0.083、0.125、0.167、0.25、0.5)超晶胞体系进行优化计算、能量计算和弹性模量计算,得到晶格常数、弹性模量、电荷分布、能带结构和态密度图.研究表明:掺杂能够使得材料的弹性模量大幅减小,对应的硬化函数值降低,易于材料加工;在电性质方面,掺杂后,材料均属于直接带隙半导体材料.当x0.25时,由于掺杂浓度过高使得晶格发生畸变,电性质与未掺杂情况类似;当x0.25时,随着掺杂浓度的降低,导带收缩加剧,局域性增强,禁带宽度变窄,使得电子从价带受激跃迁所需能量降低,故掺杂后材料表现出半金属性,导电性增强.     

掺W纳米TiO2材料改性与光催化性能研究

溶胶-凝胶被广泛用来制备纳米氧化物材料。以钛酸丁酯为先驱体,冰醋酸为螯合剂,通过水解缩聚作用制备了纳米TiO2,掺杂钨元素对纳米TiO2进行改性,运用X射线衍射(XRD)和透射电镜(TEM)及光吸收等手段,研究了不同掺杂量对TiO2相变和光催化活性的影响,确定了最佳的掺杂量和热处理温度。     

Luminescence of novel terbium complex/inorganic/polymeric hybrid materials based on sol-gel technology

In this paper, a new terbium complex/inorganic/polymeric molecular hybrid material was prepared and its optical properties were studied. At first, 4-nitrobenzoic acid was modified by (3-aminopropyl) trimethoxysilane to form a precursor and coordinated with terbium ion. Then it was polymerized with inorganic host tetraethoxysilane or polymer host polyvinyl alcohol and formed hybrid material. ¹H NMR Fourier transform infrared (FT-IR), scanning electron microscope and TGA were applied to characterize the structure of the precursor. UV-vis spectrophotometer and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb³⁺ substantiates optimum energy couple and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb³⁺.     

主客体掺杂和空穴阻挡对蓝色磷光OLED发光性能的影响研究

以铱配合物蓝色磷光材料Firpic作为掺杂剂,制备了基于CBP为主体的蓝色有机电致发光器件,其结构为ITO/CuPc/FIrpic:CBP(x%)/BCP/Alq3/LiF/Al,其中x%为发光层主客体掺杂浓度.分别研究了主客体掺杂浓度和空穴阻挡层BCP的厚度对器件发光性能的影响,当掺杂浓度为8%时,主客体间的能量传转移最充分,器件的启亮电压为5V,器件在20V时的亮度为7122.25cd/m2.器件电致发光(EL)光谱出现明显的红移现象,为Alq3部分参与了发光,影响了发光的色纯度,改变BCP的厚度,可以调节载流子复合区域和器件发光的色度坐标,达到改善器件发光性能的目的.     

Enhancement of photoconduction in a conjugated polymer through doping with copper nanoparticles

We investigated the effect of doping with copper nanoparticles (Cu NPs) on photoconductivity of poly(3-hexylthiophene) P3HT films. ∼20 nm Cu NPs were fabricated in a simple one step reduction process in hydrophobic environment. Structure, morphology and optical properties of the Cu nanoclusters were characterized. Films of P3HT containing Cu NPs were fabricated and their optical and electrical properties investigated. The results indicate that the change of the efficiency of the light absorption brought about by the effect of plasmonic resonances is minor, but there is a substantial influence of the metal nanoparticles on the efficiency of the photogeneration of charges in P3HT.     

Thermoelectric Properties of the Layered Compound GeBi4Te7 Doped with Copper

The effect of Cu doping (0.05–0.20 at. %) on the thermoelectric and transport properties of the layered compound GeBi₄Te₇ (with a small Ge deficiency) was studied. According to x-ray diffraction data obtained on cleaved (001) surfaces, Cu doping increases the c cell parameter, presumably because some of the Cu atoms are incorporated in the van der Waals gaps between the five- and seven-layer slabs. In addition, Cu doping reduces lattice thermal conductivity and increases electron mobility. The thermoelectric figure of merit of the material with the optimum Cu content (0.05 at. %) is ZT = 0.65 around 330 K.     

前驱体对含Cu低碳钢I&Q&P处理后组织性能的影响

采用IQP工艺和EPMA、SEM和XRD等手段,研究了3种前驱体对含Cu低碳钢残余奥氏体含量及力学性能的影响。结果表明,双相区保温初期试验钢奥氏体长大由C配分控制,后期由合金元素Mn、Cu配分控制;双相区保温奥氏体化后,双相区配分后形成弥散分布的局部高浓度Mn、Cu区域仍保留富集效果,在随后的淬火-碳配分阶段易于形成残余奥氏体。经IQP处理后,前驱体为P+F的钢室温组织中马氏体板条较粗,原始奥氏体晶界并不明显;前驱体为F+M钢得到的马氏体板条有序细密;前驱体为M的钢室温组织中马氏体板条更加细密。其中,前驱体组织为M的钢中残余奥氏体量最高,延伸率为24.1%,强塑积可达25 338 MPa·%,综合性能最好。     

浸渗掺杂技术在制备半透明氧化铝陶瓷中的应用

实验证实了可以使用液相前驱体浸渗技术来均匀引入添加剂和制备半透明氧化铝陶瓷。首先在不同的浸渗条件下使用硝酸钇的水溶液浸渗了预烧的氧化铝坯体。通过线扫描表征了沿坯体厚度方向上的钇元素分布情况, 发现当试样厚度更小, 溶液浓度更低时, 钇元素分布更加均匀, 而且引入量的调控也更为精确。通过假设气孔被溶液完全填充, 提出了预测浸渗引入理论量的公式。最后使用浸渗方法制备了透明氧化铝陶瓷, 发现与球磨制备的样品相比, 浸渗制备的材料显微组织更为均匀, 透光性能也更好。     

Investigations on surface composition and microstructure of sintered barium titanate

The paper describes studies on surface atomic composition, microstructure and microarea elemental distribution in sintered undoped as well as donor or acceptor doped polycrystalline barium titanate ceramics. The specimens examined are derived from barium titanate powders synthesized by two different wet chemical procedures namely oxalate precursor route and gel-to-crystallite conversion. The compositional analysis is carried out by backscattering spectrometry (BS) involving 3.05 MeV ¹⁶O(α,α)¹⁶O resonant scattering while investigations on microstructure and microarea elemental distribution are performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The specimens prepared by either method are monophasic; however, their surface atomic composition, microstructural features as well as electrical characteristics are significantly different. The specimens obtained by oxalate precursor route generally have Ti rich surfaces and exhibit coarse to fine grained microstructure depending on the nature and extent of doping. The Mn-doped specimens exhibit appreciable O deficiency. The specimens prepared by gel to crystallite conversion, in contrast, usually have Ba enriched surfaces and exhibit fine-grained microstructure. EDS measurements show the segregation of acceptors such as Mn, Cu and Zn in the grain boundaries of oxalate precursor derived ceramics. Further, the relative atomic ratio of Ti to Ba at the sites of segregations is higher compared to other locations.     

Zn_(1-x)Mn_xS稀磁半导体的合成与光学性能

通过水热法制备不同掺杂浓度的Zn_(1-x)Mn_xS(x=0.00,0.02,0.05,0.07)稀磁半导体材料,研究Mn~(2+)掺杂浓度对ZnS纳米棒微观结构和光学性能的影响。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)、X射线能量色散分析谱仪(XEDS)和紫外可见吸收光谱(UV-vis)对样品的晶体结构、形貌和光学性能进行表征。结果表明:制备的所有样品均具有结晶良好的纤锌矿结构,没有杂峰出现,生成纯相Zn_(1-x)Mn_xS纳米晶。样品形貌为纳米棒状结构,分散性良好。掺杂的Mn元素进入到ZnS纳米晶中,Mn~(2+)替代了Zn~(2+),而且随着Mn掺杂量的增加晶格常数减小。同时UV-vis光谱发现样品的光学带隙增大,发生了蓝移现象。     

共掺杂Cu-Ce/TiO_2光催化性能研究

采用溶胶-凝胶法,以钛酸丁酯为前驱体制备了不同Cu-Ce掺杂量的纳米TiO2光催化材料。通过模拟环境室内甲醛气体的降解实验,探讨了不同样品在日光灯和纯可见光下的光催化效果,并采用X射线衍射仪和紫外-可见分光光谱仪对其晶相结构与光学特性进行表征分析。结果表明,Cu-Ce掺杂能明显提高二氧化钛在可见光下的光催化活性,当Cu-Ce掺杂浓度为2.5%时,对甲醛气体的光催化降解效果最佳。     

Mn,Cu掺杂对ZnS∶Mn,Cu电致发光材料亮度的影响

采用水热法制备了ZnS∶Mn,Cu电致发光材料,利用透射电镜对发光材料的结构和形貌进行表征,并且探讨了Cu2+、Mn2+掺杂量和反应温度对ZnS∶Mn,Cu发光材料亮度的影响。结果显示,随着Cu2+、Mn2+掺杂量的增加,发光材料的亮度也随之增加,但对于Cu2+、Mn2+掺杂都存在最佳值,当Cu2+掺杂量0.2%,Mn2+掺杂量4%,温度150℃时,得到的电致发光材料亮度较高,粒径约10nm左右。     

Ni掺杂浓度对CdS:Ni体系电子和光学性质的影响

采用基于密度泛函理论框架下的第一性原理计算方法,对纤锌矿结构CdS:Ni的几何结构、能带结构、电子态密度和光学性质随Ni掺杂浓度的变化进行了系统地研究。计算结果显示,无论是在富镉,还是富硫条件下,计算得到不同Ni掺杂浓度的形成能都较小,说明CdS:Ni系统在实验上是可以实现的;Ni掺杂的CdS在价带顶附近出现杂质带,大大提高了材料的导电率。光学性质的计算结果显示,Ni掺杂后体系的光学性质有很大的改变,在吸收光谱上产生了新的吸收峰,并且随着掺杂浓度的增加,吸收范围增大。所有结果表明,CdS:Ni体系是极具潜力的透明导电材料。     

Li-Cu共掺杂ZnO纳米薄膜的溶胶凝胶法制备

采用溶胶-凝胶法,通过调整氯化锂和氯化铜的摩尔比在不同基片上制备了不同Li-Cu共掺杂浓度的ZnO薄膜.利用X射线衍射仪、扫描电子显微镜、透射电子显微镜、紫外可见光分光光度计和伏安特性测试等表征了薄膜的结晶状况、表面形貌及光电特性.结果表明:所得Li-Cu共掺杂ZnO薄膜为六角纤锌矿多晶结构,有CuO杂质相生成.随Li和Cu摩尔比增加,共掺杂ZnO薄膜结晶度增强,晶粒长大,样品表面不平整度增加.CuO颗粒的出现,使得共掺杂ZnO薄膜透射率降低,透光性较差.Li与Cu摩尔比为1∶1时,共掺杂ZnO薄膜的综合导电性最好.