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首页> 外文期刊>Philosophical magazine, B. Physics of condensed matter, electronic, optical, and magnetic properties >Structure and chemistry of Ag-Cu nanoclusters in a silica matrix by the sol-gel process
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Structure and chemistry of Ag-Cu nanoclusters in a silica matrix by the sol-gel process

机译：溶胶-凝胶法在二氧化硅基体中Ag-Cu纳米团簇的结构与化学

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Mixed Ag-Cu nanoclusters with doped silica coatings were prepared by the sol-gel process and characterized by conventional transmission electron microscopy, nanodiffraction, energy-dispersive X-ray spectrometry, high-resolution transmission electron microscopy and related Fourier transforms and optical absorption spectroscopy. This study reports on the results of two samples with Cu-to-Ag molar ratios of 1 and 3 respectively. A constant (Ag + Cu)-to-SiO2 molar ratio of 0.175 was maintained in both cases. Optical absorption spectra of the coated samples exhibit surface plasmon resonance bands characteristic of both Ag and Cu metallic clusters after heat treatment in 5% H-2-95% N-2 atmosphere at 700 degrees C. The transmission electron microscopy was performed in order to correlate the Cu-to-Ag molar ratio with the modification of the optical properties. A different cluster size distribution was found for the two different molar ratios. A bimodal distribution was found for a Cu-to-Ag ratio of 1, while a more homogeneous monomodal cluster distribution was obtained for the sample with a Cu-to-Ag ratio of 3. Both materials show the presence of Ag and Cu clusters as separate crystalline phases. In case of the Cu-to-Ag ratio of 3, electron microscopy results suggest the presence of a superstructure and/or a Cu-Ag alloy in the clusters.
机译：通过溶胶-凝胶法制备了具有掺杂二氧化硅涂层的混合Ag-Cu纳米团簇，并通过常规透射电子显微镜，纳米衍射，能量色散X射线光谱，高分辨率透射电子显微镜以及相关的傅里​​叶变换和光学吸收光谱进行了表征。这项研究报告了铜与银的摩尔比分别为1和3的两个样品的结果。在两种情况下，均保持恒定的（Ag + Cu）/ SiO2摩尔比为0.175。在5％H-2-95％N-2气氛中，在700℃下进行热处理后，涂覆样品的光吸收光谱显示出Ag和Cu金属簇的表面等离振子共振带的特征。使铜与银的摩尔比与光学性质的改变相关。对于两种不同的摩尔比，发现了不同的簇尺寸分布。发现铜与银之比为1的双峰分布，而铜与银之比为3的样品获得更均一的单峰簇分布。两种材料均显示存在Ag和Cu簇分离的结晶相。在Cu与Ag之比为3的情况下，电子显微镜结果表明在簇中存在上层结构和/或Cu-Ag合金。

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