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实验采用γ-射线辐照法制备聚乙烯醇栽纳米银复合材料。在水体系中,由γ-射线辐照使水激发产生还原性粒子,水合电子,它将Ag^+还原成银原子,银原子聚集形成纳米粒子,被载在所加入的聚乙烯醇上,形成复合材料。通过紫外-可见分光光度计和透射电镜对产物的特征进行表征。采用不加表面活性剂的情况下制备聚乙烯醇载纳米银复合材料,并用透射电镜测量其粒径大小,结果表明用此法可制得50nm左右的纳米银粒子。 相似文献
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本文论述了在常温常压、无任何催化剂的条件下,通过电子束辐照制备纳米钴。利用X射线衍射仪(XRD)、透射电子显微镜(TEM)和差热分析仪(DSC)分别分析了纳米钴的结构、行貌、大小和熔点。利用激光散射粒度分布仪(LSPSDA)观察了纳米钴的粒度分布,并用样品振荡磁力计(VSM)分析了纳米钴的磁性。结果表明实验所制得的纳米钴粒子平均粒径32nm,粒度分布窄,熔点显著降低。最后,探讨了纳米钴的形成机理。 相似文献
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微乳液法制备纳米银粒子 总被引:24,自引:3,他引:24
采用SDS/异戊醇/二甲苯/水体系,用水合肼还原硝酸银制备了钠米级银粒子,并考察了体系中含水量,粒子浓度及异戊醇含量等因素对银粒径大小的影响。 相似文献
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利用磁控溅射在玻璃衬底上制备Ag纳米粒子及其氧化物(AgOx)薄膜,通过高温退火实验,研究银及AgOx薄膜的热稳定特性。采用x射线衍射分析薄膜的晶相结构,采用UV-Vis分光光度计测定薄膜的吸收光谱。结果表明:Ag纳米薄膜在450nm附近出现特征吸收峰,200℃退火后,峰位蓝移,400℃退火后,吸收峰显著减弱,表明Ag纳米粒子在退火过程中发生了蒸发;AgOx薄膜在200℃下退火后,出现Ag纳米粒子特征吸收峰,表明AgOx的热分解,400℃退火同样导致Ag纳米粒子的蒸发。 相似文献
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用可聚合表面活性剂在超声辐照下乳液聚合制备聚苯乙烯纳米粒子 总被引:3,自引:0,他引:3
合成了一种离子型可聚合表面活性剂马来酸酐衍生物磺酸钠(M12),它既可作为乳化剂又能充当引发剂,在超声辐照下乳液聚合制备了聚苯乙烯纳米粒子。产物的红外光谱分析表明,可聚合表面活性剂与苯乙烯发生了共聚,随M12加入量的增加,M12共聚组成提高。用凝胶渗透色谱、透射电镜对超声辐照乳液聚合产物的分子量、乳胶粒形貌和大小进行了表征,发现得到的是高分子量(>106)的聚苯乙烯纳米粒子,粒径为15nm~45nm,分布较窄。对该聚合反应影响因素的研究结果表明,表面活性剂M12浓度增加、超声波输出功率增加、温度升高、加快氮气流速和单体浓度减少都有利于提高单体转化率。 相似文献
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采用溶胶-凝胶法制备了TiO2和Ag/TiO2纳米粒子,采用涂覆法制备了TiO2和Ag/TiO2纳米粒子光催化剂基板样品。使用XRD、SEM和拉曼光谱等手段,对TiO2和Ag/TiO2纳米粒子进行了晶格结构和表面形貌研究;通过UV-Vis,研究了TiO2和Ag/TiO2纳米粒子光催化剂基板样品在光催化反应器中对苯酚的光催化降解性能。结果表明,制备的TiO2和Ag/TiO2纳米粒子均为纯净的金红石相,二者表面形貌并没有明显区别,Ag单质粒子成功负载在TiO2纳米材料上;Ag单质粒子的负载,明显增强了TiO2纳米粒子对可见光的吸收,且Ag/TiO2纳米粒子薄膜对苯酚的光催化降解性能明显优于TiO2纳米粒子薄膜;在光催化降解1 h后,TiO2纳米粒子薄膜仅催化降解了溶液中30%(质量分数)的苯酚,且光催化降解出现了饱和趋势,而Ag/TiO2纳米粒子薄膜可催化降解溶液中50%(质量分数)的苯酚,且在光催化降解3 h后,仍未出现饱和趋势。 相似文献
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在微波辐照下,以硝酸银为银源,水为溶剂,聚乙烯吡咯烷酮(PVP)为稳定剂和还原剂,不加入其他还原剂的条件下,快速制备出纳米银胶体。利用紫外光谱法,对微波制备纳米银粒子的条件进行了一系列研究,得出了先40℃下预热15min,再微波辐照30min,微波功率为260W,AgNO3∶PVP=1∶3(质量比)为最佳制备条件。对制得的纳米银粒子进行了TEM、SPM、DTA表征,发现制得的纳米银粒子为球形粒子,粒径较小,且粒径分布较窄,为18~25nm。对PVP的作用机理研究认为:主要是由于Ag离子与PVP的配位作用和PVP的空间位阻效应,使得能够制备出纳米球形银粒子。 相似文献
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Kevin M. Roccapriore Shin-Hum Cho Andrew R. Lupini Delia J. Milliron Sergei V. Kalinin 《Small (Weinheim an der Bergstrasse, Germany)》2022,18(1):2105099
Spatial confinement of matter in functional nanostructures has propelled these systems to the forefront of nanoscience, both as a playground for exotic physics and quantum phenomena and in multiple applications including plasmonics, optoelectronics, and sensing. In parallel, the emergence of monochromated electron energy loss spectroscopy (EELS) has enabled exploration of local nanoplasmonic functionalities within single nanoparticles and the collective response of nanoparticle assemblies, providing deep insight into associated mechanisms. However, modern synthesis processes for plasmonic nanostructures are often limited in the types of accessible geometry, and materials and are limited to spatial precisions on the order of tens of nm, precluding the direct exploration of critical aspects of the structure-property relationships. Here, the atomic-sized probe of the scanning transmission electron microscope is used to perform precise sculpting and design nanoparticle configurations. Using low-loss EELS, dynamic analyses of the evolution of the plasmonic response are provided. It is shown that within self-assembled systems of nanoparticles, individual nanoparticles can be selectively removed, reshaped, or patterned with nanometer-level resolution, effectively modifying the plasmonic response in both space and energy. This process significantly increases the scope for design possibilities and presents opportunities for unique structure development, which are ultimately the key for nanophotonic design. 相似文献
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Fengqi Song Tingyu Wang Xuefeng Wang Changhui Xu Longbing He Jianguo Wan Christian Van Haesendonck Simon P. Ringer Min Han Zongwen Liu Guanghou Wang 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(3):446-451
Anisotropic plasmon coupling in closely spaced chains of Ag nanoparticles is visualized using electron energy‐loss spectroscopy in a scanning transmission electron microscope. For dimers as the simplest chain, mapping the plasmon excitations with nanometer spatial resolution and an energy resolution of 0.27 eV intuitively identifies two coupling plasmons. The in‐phase mode redshifts from the ultraviolet region as the interparticle spacing is reduced, reaching the visible range at 2.7 eV. Calculations based on the discrete‐dipole approximation confirm its optical activeness, where the longitudinal direction is constructed as the path for light transportation. Two coupling paths are then observed in an inflexed four‐particle chain. 相似文献
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氢电弧等离子体法制备碳包铁纳米粒子 总被引:5,自引:0,他引:5
采用氢电弧等离子体法制备了碳包铁纳米粒子,通过X射线衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)、X射线能谱仪(EDS)、热重-差热分析仪(TG-DSC)等分析手段对粒子的成分、形貌,相结构,热性能等进行了表征.结果表明,制备的粒子中含有α-Fe、Fe3 C、无定形碳和石墨,没有铁的氧化物相出现.铁粒子外碳层的厚度为5~15nm,碳包铁纳米粒子的熔点为1360℃,碳层的存在增强了纳米粒子的抗酸蚀能力. 相似文献
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Yujie Xiong Mark Brunson Juyoung Huh Aaron Huang Adam Coster Kristy Wendt Justin Fay Dong Qin 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(15):2628-2638
The role of surface chemistry on the toxicity of Ag nanoparticles is investigated using Saccharomyces cerevisiae yeast as a platform for evaluation. Combining the shape‐controlled synthesis of Ag nanoparticles with a comprehensive characterization of their physicochemical properties, an understanding is formed of the correlation between the physicochemical parameters of nanoparticles and the inhibition growth of yeast cells upon the introduction of nanoparticles into the cell culture system. Capping agents, surface facets, and sample stability—the three experimental parameters that are inherent from the wet‐chemical synthesis of Ag nanoparticles—have a strong impact on toxicity evaluation. Hence, it is important to characterize surface properties of Ag nanoparticles in the nature of biological media and to understand the role that surface chemistry may interplay to correlate the physicochemical properties of nanoparticles with their biological response upon exposure. This work demonstrates the great importance of surface chemistry in designing experiments for reliable toxicity evaluation and in mitigating the toxicity of Ag nanoparticles for their safe use in future commercialization. 相似文献
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《Journal of Experimental Nanoscience》2013,8(12):937-946
Surface properties of Ag nanoparticles may not be perturbed when they are filled with the relatively cheap Cu. To better understand how Ag can be coated on Cu, growth of the Cu and Ag bimetal during the temperature-programmed carbonisation (TPC) of Ag+- and Cu2+-β-cyclodextrin (CD) complexes having the Cu/Ag ratios of 0.5, 1 and 2 was studied by in situ synchrotron small angle X-ray scattering (SAXS) spectroscopy. The SAXS spectra provide the detailed structural changes corresponding to the growth of Ag and Cu nanoparticles as the Ag+- and Cu2+-CD complexes are carbonised at the temperature range of 363–513 K. It seems that Cu having a relatively high surface free energy is enriched in the core of the cherry-like Cu@Ag bimetal nanoparticles. The Cu@Ag bimetals are encapsulated in the carbon-shell formed from carbon unconsumed in the oxidation of CD during TPC. A rapid growth of the bimetal nanoparticles occurs at 393–423 K. As Ag+ and Cu2+ are reduced during the CD oxidation, the Ag nanospheres are filled with Cu, and eventually encapsulated in the carbon-shell. Note that the carbon-shell coated on Cu@Ag can be removed by steam reforming at 573 K. 相似文献
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纳米铁颗粒在磁性、催化和吸波等方面都展现了优异的特性,具有广阔的应用前景。在过去的几十年里,国内外许多学者开展了对纳米铁颗粒制备、结构和性能的研究。着重阐述了纳米铁颗粒的气相法制备方法,并指出了这一领域今后的研究方向。 相似文献
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球形纳米银粒子制备新方法及其表征 总被引:1,自引:0,他引:1
采用水热法,不添加任何还原剂,在表面活性剂聚乙烯吡咯烷酮(polyvinyl pyrrolidone,PVP)的保护下,热分解碳酸银制得纳米银溶胶.将纳米银溶胶经过后续离心分离,干燥后得到纳米银粉.通过改变反应温度、反应时间、表面活性剂浓度、种类及反应物浓度等反应条件,分析了各反应条件对纳米银粒子形貌的影响.利用X射线衍射仪(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)和电子能谱仪(energy dispersivespectroscopy,EDS)分析表明,在反应温度为180℃、反应时间为5 h、AgNO3浓度为0.1 mol/L、NaHCO3浓度为0.05mol/L、PVP为1.7 g的最佳制备工艺条件下,纳米银粒子为球形,粒径分布范围窄,单一分散,粒径40 nm左右.结果表明,表面分散剂PVP以及AgNO3与NaHCO3的浓度对球形纳米银的合成具有关键作用. 相似文献