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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Grain size dependence of physico-optical properties of nanometallic silver in silica aerogel matrix
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Grain size dependence of physico-optical properties of nanometallic silver in silica aerogel matrix

机译：二氧化硅气凝胶基质中纳米金属银的物理光学性质的粒度依赖性

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摘要

Synthesis of silver nanoparticles in silica aerogel matrix by sub-critical drying technique is reported in the present article. Physical characterization of silver/silica aerogel nanocomposites with 1, 5 and 25 wt% of silver has been discussed. Physico-optical properties of the composites have been evaluated as a function of the silver particle size crystallized within the silica matrix. The maximum size of the silver grains that could be accommodated in the amorphous matrix was observed to be 25 nm. Silver particles of diameter larger than 25 nm were found segregated out of the silica matrix; such silver particles were single crystalline with dendritic morphology. Optical absorption analysis confirmed the presence of both the oligomeric and nanometallic silver in the samples heat-treated up to 500 degrees C. With decreasing silver particle size, the surface plasmon resonance was found first to shift towards blue followed then by a red shift. The blue shift is attributed to the chemisorption occurring between the metallic core and the silica matrix. With larger grain size of 25-80 nm in 25 wt% Ag-silica aerogel sample, the diffuseness of electron cloud outside the potential well was observed to cause a red shift in the surface plasmon resonance. (c) 2006 Elsevier B.V. All rights reserved.
机译：本文报道了通过亚临界干燥技术在二氧化硅气凝胶基质中合成银纳米颗粒。已经讨论了具有1、5和25重量％的银的银/二氧化硅气凝胶纳米复合材料的物理表征。已经评估了复合材料的物理光学性能，作为在二氧化硅基质中结晶的银粒径的函数。观察到可容纳在非晶基质中的银晶粒的最大尺寸为25nm。发现直径大于25 nm的银颗粒从二氧化硅基质中分离出来;这样的银颗粒是具有树枝状形态的单晶。光吸收分析证实了在热处理至500摄氏度的样品中同时存在低聚和纳米金属银。随着银颗粒尺寸的减小，发现表面等离子体激元共振首先向蓝移，然后向红移。蓝移归因于在金属芯和二氧化硅基质之间发生的化学吸附。在25％（重量）的Ag-二氧化硅气凝胶样品中，晶粒尺寸较大，为25-80 nm，观察到电子云在势阱之外的扩散导致表面等离振子共振发生红移。 （c）2006 Elsevier B.V.保留所有权利。

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