直接置换法制备包覆型纳米铜-银双金属粉末

以AgNO3为主盐,采用直接置换法初步制备了包覆型纳米铜-银双金属粉末,分析了工艺条件对包覆效果的影响,并用透射电子显微镜、X射线能量色散谱仪和X射线衍射仪进行了表征。实验结果表明：纳米铜-银双金属粉末为包覆型结构,平均粒径约70 nm,分散性较好,表面银的原子分数达到74.28%。在洗涤过程中加入一定量的保护剂,有效解决了纳米铜粉的氧化问题。     

空心阴极辉光放电包覆铜纳米粉末

简要叙述了自悬浮定向流方法制备铜纳米粉末的原理和包覆层薄膜的生长机理,采用空心阴极辉光放电对铜纳米粉末进行有机包覆,实验中CH4和H2的流量分别为6 ml/min和12 ml/min,工作电压为450 V,衬底与空心阴极的底端距离为2 cm,背景真空和工作气压分别为6 Pa和100 Pa,沉积速率为7.5 nm/min。用透射电镜(TEM)对铜纳米粉末进行了观察和分析,结果表明：铜纳米粉末呈球状,其粒径分布在10～100 nm之间, 平均粒径大小为50 nm;其包覆层的厚度大约为15 nm,而且该厚度可以通过调节空心阴极辉光放电的参数来控制。     

空心阴极辉光放电包覆铜纳米粉末

 简要叙述了自悬浮定向流方法制备铜纳米粉末的原理和包覆层薄膜的生长机理，采用空心阴极辉光放电对铜纳米粉末进行有机包覆，实验中CH4和H2的流量分别为6 ml/min和12 ml/min，工作电压为450 V，衬底与空心阴极的底端距离为2 cm，背景真空和工作气压分别为6 Pa和100 Pa，沉积速率为7.5 nm/min。用透射电镜(TEM)对铜纳米粉末进行了观察和分析，结果表明：铜纳米粉末呈球状，其粒径分布在10～100 nm之间, 平均粒径大小为50 nm；其包覆层的厚度大约为15 nm，而且该厚度可以通过调节空心阴极辉光放电的参数来控制。     

青霉胺稳定的铜/银双金属纳米簇制备及其在银离子检测中的应用EI北大核心CSCD

以青霉胺(DPA)为还原剂和稳定剂,通过一锅法一步制备了青霉胺稳定的铜/银双金属纳米簇(DPA-Cu/Ag NCs),并将其作为一种传感器用于检测水样中的银离子。该银离子传感器具有价格低廉、分析速度快速、选择性高等特点。采用透射电子显微镜(TEM)等方法表征了DPA-Cu/Ag NCs的结构及其化学组成,并通过荧光光谱和紫外-可见光谱法研究了DPA-Cu/Ag NCs的光学性质。结果表明,该DPA-Cu/Ag NCs在激发波长为300 nm时的最大发射波长为555 nm,其溶液在可见光照射下呈现乳白色,在紫外灯照射下则呈现出明亮的黄色荧光。在DPA-Cu/Ag NCs的制备条件达到最优化的情况下,可以将其作为探针,用来高选择性、高灵敏性地检测银离子。该探针检测银离子的检测限为0.3μmol/L,线性范围为0~500μmol/L。该DPA-Cu/Ag NCs探针还可应用于自然环境水样(湖水、瓶装矿泉水和实验室自来水)中银离子浓度的检测,其检测性能十分优异且具有良好的准确度和重现性,表明DPA-Cu/Ag NCs探针在环境检测方面有非常高的应用价值。     

用电爆炸丝法制备纳米粉末及负载型纳米催化剂

目前制备纳米材料的方法很多，其中电爆炸丝法制备纳米粉末材料是20世纪90年代后期发展起来的新型方法，俄罗斯和日本研究人员利用该方法成功制备多种金属和金属化合物纳米粉末。我国吉林大学利用该方法制备了纳米Cu-Zn合金粉末，其粒度分布在30～180nm，平均粒度约85nm。为了探索电爆炸金属丝技术在制备纳米粉末及其相关产品中的应用前景，文中对电爆炸金属丝产生纳米Al2O3和TiO2进行了实验研究，并在此基础上开展了电爆炸金属丝制备负载型纳米催化剂的初步研究。     

超声波辅助电解方法制备金属纳米粉末

研究利用电磁感应加热一自悬浮定向流技术合成金属纳米粉末。然而，这种技术很难制备出高熔点的金属纳米粉末，如W，Mo。而超声波辅助电解方法正好可以弥补这个缺陷。尽管超声波辅助电解方法操作简单，但是它能合成高产额的纳米粉末。因此，这种方法很适合于工业生产。     

室温固相反应制备AgX纳米粉末

首次利用ＡｇＮＯ３与ＫＸ（Ｘ为Ｃｌ＾－,Ｂｒ＾－,Ｉ＾－）的室温固相反应成功地年鉴轩出纳米ＡｇＸ粉末。并结合ＸＲＤ,ＴＥＭ,ＴＧ／ＤＴＡ测试对其结构和性能进行了表征。发现固相反应制得的超细ＡｇＸ与水相法制得的相应常粒ＡｇＸ颜色有所不同。     

微波合成银包覆金纳米粒子膜的拉曼散射活性研究

采用微波加热加压法和静电吸附自组装法在石英玻璃表面制备了银包覆金纳米粒子薄膜,利用原子力显微镜分析了薄膜的表面形态和结构,测定结晶紫分子在薄膜表面的拉曼光谱。结果表明,银包覆金纳米粒子薄膜具有很强的表面增强拉曼散射效应(SERS)活性和稳定性。     

柠檬酸盐热分解法制备纳米YBCO超导粉末

利用硝酸盐为起始原料,硝酸为氧化物,柠檬酸为络合剂和燃料,氨水为酸碱中和剂,制备了稳定的柠檬酸盐络合物。柠檬酸盐络合物经高温燃烧分解,获得了YBCO粉体。粉体在960℃氧气条件下退火8小时后压制成块再在960℃氧气条件下退火7小时。利用X-射线对块体进行物相分析,利用标准四接线柱法对块体进行R-T分析,结果发现有比较纯的相,根据Scherrer公式计算得到样品的平均晶粒尺寸约为18nm,起始转变温度约为84.9K,表现出良好的超导电性,并且我们从理论上预言了整个化学反应过程的机理,得出结论:反应物中的柠檬酸与金属阳离子的物质的量之比应不低于0.722。实验结果与理论分析完全一致。     

退火法制备石墨烯-银纳米粒子及其增强拉曼实验

针对目前SERS基底上金属颗粒制备过程中存在的分布不均匀、易氧化和稳定性差等缺点,通过热蒸镀和高温退火获得分布均匀的SERS基底;同时结合石墨烯优良的光学性能、化学惰性、荧光猝灭以及本身的SERS增强等优点,制备了稳定的石墨烯-银纳米颗粒（GE/AgNPs）复合结构SERS基底。通过GE/AgNPs复合结构的拉曼光谱稳定性试验证明了石墨烯在GE/AgNPs结构中起到隔绝银纳米颗粒与空气直接接触及催化氧化银脱氧的作用,有利于SERS基底的时间稳定性。(1) 石墨烯、Ag纳米颗粒及其复合结构的制备。首先采用热蒸镀和高温退火的方法使Ag纳米颗粒均匀地沉积在SiO₂/Si基底上,再采用化学气相沉积法在Cu箔上制备少层石墨烯,并用湿法转移法将石墨烯转移到目标基底上,并实验研究了以不同的退火顺序对GE/AgNPs基底造成的影响。(2) 石墨烯、Ag纳米颗粒及其复合基底的表征。分别采用光学显微镜、扫描电子显微镜和拉曼光谱进行表征,得到转移后的纯石墨烯较完整地覆盖在SiO₂/Si基底上面,表面比较平整,但在少数地方仍然存在褶皱和杂质;SEM表征结果表明对于不同制备流程的GE/AgNPs复合结构上的Ag纳米颗粒基本呈球形。基本符合Ostwald熟化理论,通过对退火温度和时间的控制能获得平均粒径在40~60 nm的银颗粒,且分布较均匀。此外,在不同退火顺序中,石墨烯的加入对银纳米颗粒的扩散形成扩散势垒,从而出现较大的不规则的颗粒。(3) 基底稳定性试验和仿真分析。通过基底本身的Raman mapping测试,分析了石墨烯拉曼特征峰峰值和半高宽的变化,得知基底对石墨烯本身的拉曼增强效果主要来源于银纳米颗粒间的电磁场增强。同时采用浓度为10-6 mol·L-1的罗丹明6G (R6G)水溶液作为探针分子,对转移了石墨烯的GE/AgNPs复合基底和未转移石墨烯的Ag纳米颗粒基底进行了SERS稳定性实验。结果表明GE/AgNPs复合基底在1~33 d内衰减较缓慢,30 d后仍能探测到拉曼信号约为原来信号的35.1%~40.6%;而纯Ag基底上随着Ag纳米颗粒在空气中迅速氧化,基底的SERS性能显著下降,在30 d后只有原来信号的5.9%~11.3%。此外,通过实验得到覆盖了石墨烯之后的增强因子约为6.05×105。最后采用时域有限差分算法（FDTD）计算了复合结构的电磁场分布和理论增强因子,其理论增强因子可以达到5.7×105。实验和仿真结果的差异,主要是源于石墨烯的化学增强作用。     

Preparation of a novel infrared low-emissive coating from the Cu powder modified by the polyethylene wax

Cu powder was coated with polyethylene wax via the flux-capping method in hope to avoid the oxidation of it, so the increment of the infrared emissivity of the coating can be greatly reduced. The prepared product was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The infrared emissivity of the prepared material was measured by Infrared Emissometer. The influence parameters that will affect the emissivity of the coating were systematically investigated, such as the content of coated Cu powder, coating fineness, coating thickness and aging process. The results indicated that the infrared emissivity value of the coating was reduced after Cu powder was coated with polyethylene wax. The polyethylene wax/Cu composites presented a homogenous sheet structure when the content of Cu powder increased to 30 wt.%, and it has a lower emissivity. The infrared emissivity of the coating increases rapidly as thickness increases and becomes steady above thickness of 70 μm. The composite coating exhibits lower emissivity value and excellent physical properties at coated Cu content of 20 wt.%. The emissivity of the coating that was prepared from the modification of the Cu powder was decreased with the decrement of the grinding fineness and increased with the aging time. The emissivity of the coating that was prepared from the modification of the Cu powder is always lower than that of the coating that only composed of the Cu powder with the increment of the aging time. Therefore, it can be concluded that the anti-oxidation of Cu powder is greatly improved after it was modified by polyethylene wax, which results in a novel coating with long-run low emissivity.     

Ag-Cu双金属团簇中Ag原子偏析行为的 分子动力学研究

采用了恒温分子动力学方法系统模拟研究了不同尺寸不同组分的Ag-Cu双金属团簇的退火过程。分析低温退火结构可得团簇中Ag原子的偏析行为：在Ag原子所占比率较少时,Ag原子全部占据在团簇表面;随着Ag原子数的增多,直到Ag和Cu的比率接近时,绝大多数Ag原子仍占据在团簇表面;这与实验观测Ag-Cu混合团簇中Ag原子的偏析行为完全一致。通过细致研究Ag-Cu双金属团簇中Ag原子的偏析行为与团簇尺寸、组分和温度的关系发现：当Ag原子所占比重明显少于Cu原子时,在各不同尺寸下,Ag原子偏析温度点均高于熔点,即在熔点以上一定温度范围内仍会出现Ag原子的偏析现象;当Ag原子所占比重明显多于Cu原子时,在各不同尺寸下,体系偏析温度点均低于团簇熔点;对于较大尺寸团簇,在Ag原子所占比重接近于Cu原子时,体系偏析温度点与团簇熔点相同。     

冷速对Cu10Ag90合金凝固结构的影响

通过分子动力学对液态Cu10Ag90合金在四种冷速条件下进行快速凝固模拟。结果显示,1 × 1010和1 × 1011 K/s下系统的平均原子能量分别在750 K和650 K发生突变,冷速越低最终平均原子能量越低;1 × 1012和1 × 1013 K/s的双体分布函数第二峰出现分裂,表明结构处于非晶态。从1 × 1011K/s开始出现尖锐小峰,表明此冷速开始出现晶化现象,1 × 1010 K/s下分裂的峰更加尖锐明显,说明体系形成结晶度较高的晶体结构;1 × 1010 和1 × 1011 K/s下系统凝固后晶体结构含量由高到低分别为fcc, hcp, bcc。冷速越低晶体结构数目越多,系统的有序度更高,结构熵越低。     

Synthesis and structural investigation of Pd/Ag bimetallic nanoparticles prepared by the solvothermal method

Pd/Ag bimetallic nanoparticles have been synthesized successfully by reducing PdCl₂ and AgNO₃ mixture in ethylene glycol solution using the solvothermal method. The prepared samples have been characterized by UV–vis, XRD, TEM, HRTEM, EDS, and XPS, respectively. Moreover, the bimetallic particles possess alloy and core-shell structure from the HRTEM images. Here, the lattice fringe spacing of Pd/Ag bimetallic nanoparticles corresponds to its (111) plane, which is between that of the Pd and Ag nanoparticles prepared under the same conditions. Furthermore, the possible formation mechanism and factors influencing the formation of Pd/Ag bimetallic nanoparticles, such as reaction temperature and time, have also been investigated.     

团簇连接对Cu10Ag90快速凝固中晶体结构的影响

快速凝固得到的晶体通常都会形成多种孪晶结构,但其成因一直是一个谜。本文采用分子动力学模拟Cu10Ag90合金在0、20和40 GPa压强下的快速凝固过程,分别形成了五重孪晶、层片状孪晶和复杂晶体,通过最大标准团簇方法(LaSCA)分析了短程有序结构的演变和晶体团簇之间的连接形式。结果发现,结晶转变温度Tc随着压强的增大而升高,平均原子势能也随之增加。非晶共有近邻子团簇(CNS)会在温度降至Tc时转变为晶体CNS,同时晶体团簇数量急剧增加,结构有序度提升。此外,通过分析晶体团簇之间的连接方式发现,五重孪晶中心团簇截边十面体(tDh)只能与具有相同S422的HCP相连形成五重孪晶轴;FCC与HCP有相同的S421,但只能以彼此的顶层或者底层原子作为彼此的中心原子连接形成层片状结构;BCC与FCC、HCP虽然没有共同的CNS,但是可以通过D-S6结构及其变形体连接,其连接方式的多样性是形成复杂晶体的主要原因。这些结果为研究晶体结构不同排列方式提供了新的理解。     

Ultrasonic enhancement of microdroplet-based interfacial reaction for improving the synthesis of Ag2S QDs

Ag₂S quantum dots (QDs) have aroused extensive concerns in intravital imaging field due to their merits of narrow bandgap, low biological toxicity and decent fluorescence emission properties in the second near-infrared (NIR-II) window. However, low quantum yield (QY) and poor uniformity of Ag₂S QDs are still main obstacles for its application. In this work, a novel strategy of utilizing ultrasonic field is presented, which can enhance the microdroplet-based interfacial synthesis of Ag₂S QDs. The ultrasound increases the presence of ions at the reaction sites by enhancing the ion mobility in the microchennels. Therefore, the QY is enhanced from 2.33 % (optimal QY without ultrasound) to 8.46 %, which is the highest value of Ag₂S ever reported without ion-doping. Also, the decrease of the corresponding full width at half maximum (FWHM) from 312 nm to 144 nm indicates the obvious uniformity improvement of the obtained QDs. Further mechanism exploration illustrates that ultrasonic cavitation significantly increases the interfacial reaction sites by splitting the droplets. Meanwhile, the acoustic flow field strengthens the ion renewal at the droplet interface. Consequently, the mass transfer coefficient increases by more than 500 %, which is favorable to improve both the QY and quality of Ag₂S QDs. This work serves both fundamental research and practical production for the synthesis of Ag₂S QDs.     

多腔耦合微波表面波PECVD法沉积 DLC薄膜研究

报道了利用多腔耦合微波表面波等离子体增强化学气相沉积(PECVD)的方法制备类金刚石(DLC)薄膜。通过发射光谱(OES)测量,对Ar等离子体中的各种放电参数以及全部四个腔室内放电的均匀性作出评估。采用表面轮廓仪测量了薄膜的厚度;薄膜的表面形貌、组成结构通过原子力显微镜(AFM)、激光拉曼光谱和X射线衍射光谱(XPS)进行了表征。在12.5μm厚度的有机薄膜聚酯(PET)表面沉积一定厚度DLC后,通过测量水蒸气透过率(WVTR)对DLC薄膜的阻隔性能进行了研究。结果表明,这种多腔耦合微波表面波等离子体装置,不仅能够实现四个腔室同时相对均匀的放电,也能够实现单个腔室的轴向均匀放电。制备的DLC薄膜结构致密、成分均匀,可以使PET薄膜阻隔性能提高约20倍。     

金银三层纳米管局域表面等离激元共振特性研究

相对于单一金属纳米材料,二金属复合纳米材料具有更大的潜在应用价值.基于时域有限差分方法,研究了SiO₂-Ag-Au和SiO₂-Au-Ag二金属三层纳米管的消光光谱,并对其局域表面等离激元共振(Localized Surface Plasmon Resonance,LSPR)特性进行了分析.研究发现,内核尺寸变大将导致上述两种金属纳米管LSPR峰红移;内层金属及外层金属壳层厚度增大均会导致其LSPR峰蓝移.银壳厚度变化对纳米管LSPR的调制作用大于金壳厚度变化造成的影响.上述现象可以利用等离激元杂化理论及自由电子和振荡电子变化的竞争机制进行分析.     

Molecular simulation investigations on the coating of Al-alloy surface by nano-SiO2-epoxy composite

To improve corrosion protections, a better understanding of the coating behavior and therefore the interaction properties between the inhibitor and the surface is a vital factor. Density functional theory (DFT) simulations were used to explore the adsorption properties of the pure epoxy and nano-SiO₂-epoxy composites on the Al₂Cu surface. The interaction energies and transferred charges of adsorbed composites on the Al₂Cu surface and their optimized structures with various interacting orientations are investigated. It is found that nano-SiO₂-epoxy adsorb more strongly on Al₂Cu substrate in comparison with the epoxy matrix with interaction energies of ˗228.084 kcal/mol and ˗35.341 kcal/mol, respectively. The validity of our computational methods was evaluated by experiments as well as high-level quantum chemistry method. The atom-in-molecules analysis with DFT indicates that the interaction nature is typical for electrostatics. The stability of the adsorption behavior of composites on the surface was also explored by DFT-based molecular dynamics simulation.