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991.
In order to understand the difference in metallic film growth modes on perfect and defective oxide substrates, we have combined ab initio B3LYP periodic calculations on the slab models of the corresponding Me/MgO(0 0 1) interfaces (Me = Ag, Cu) with thermodynamic theory of solid solutions. For a defectless magnesia surface, we confirm the experimentally observed submonolayer growth of 3D metallic islands (Ag possesses a higher trend than Cu). Formation of Fs centers (neutral O vacancies) on the substrate markedly enhances metal atom adsorption as compared to physisorption over regular sites on a defect-free substrate. For the first time, we predict that the presence of these surface defects (beginning with concentrations of 5% for Cu and 22% for Ag) can stimulate the growth of uniform 2D metallic sublayers. 相似文献
992.
采用二步阳极氧化法在草酸溶液中制备了高度有序的多孔阳极氧化铝(Porous Anodic Alumina,PAA)薄膜。以多孔氧化铝薄膜为模板,采用真空电子束蒸发的方法在多孔氧化铝模板上制备出了高度有序的金属银纳米点阵列体系。扫描电镜(SEM)测试结果表明,所制备的金属银纳米点阵列与多孔阳极氧化铝膜的多孔阵列具有完全相同的有序结构,阵列中银纳米颗粒的形状接近球形,其直径大约为70nm,与氧化铝模板的孔径基本一致。研究了高度有序银纳米点阵列的形成过程。 相似文献
993.
TiO2- and Ag/TiO2-nanotubes (NTs) were synthesized by hydrothermal methods and microwave-assisted preparation, respectively. Scanning electron microscopy, high resolution transmission electron microscopy, Brunauer-Emmett-Teller particle surface area measurement and X-ray diffraction were used to characterize the nanotubes. Rutile TiO2-NTs with Na2Ti5O11 crystallinity had a length range of 200-400 nm and diameters of 10-20 nm. TiO2- and Ag/TiO2-NTs with a 0.4% deposition of Ag had high surface areas of 270 and 169 m2 g−1, respectively. The evaluation of photocatalytic activity showed that Ag/TiO2-NTs displayed higher photocatalytic activity than pure TiO2-NTs and a 60.91% degradation of Rhodamine-B with 0.8% deposition of Ag species. Also 60% of Rhodamine-6G was physisorbed and 40% chemisorbed on the surface of TiO2-NTs. In addition, the photocatalytic degradations of organochlorine pesticides taking α-hexachlorobenzene (BHC) and dicofol as typical examples, were compared using Ag/TiO2-NTs, and found that their degradations rates were all higher than those obtained from commercial TiO2. 相似文献
994.
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996.
Tomáš Křenek Nataliya Murafa Petr Bezdička Jan Šubrt Husain M. Masoudi Josef Pola 《应用有机金属化学》2012,26(3):135-139
Pulsed IR laser irradiation of metal (Au or Ag) target in gaseous tetramethyltin (TMT) results in metal ablation and adjacent dielectric breakdown (DB) in TMT and allows gas phase deposition of films containing metal (Au or Ag), Sn and C elements. Volatile products of DB of TMT were examined by FT‐IR spectroscopy and revealed as intermediates of gas phase carbonization reactions. The solid films were analyzed by FT‐IR and Raman spectroscopy, X‐ray diffraction and electron microscopy and shown as amorphous nanostructured Au–Sn/C and Ag–Sn/C phases containing β‐Sn nanograins. These Sn nanograins exhibit irreversible amorphization upon heating and melt below the melting point of bulk β‐Sn phase. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
997.
Light scattering effect of submicro-textured Ag/Al composite films prepared at lower substrate temperatures 下载免费PDF全文
We present a new and practical approach for preparing submicro-textured silver and aluminum (Ag/Al) double-structured layers at low substrate temperatures. The surface texturing of silver and aluminum double-structured layers was performed by increasing the deposition temperature of the Al layers to 270℃. The highly submicro-textured silver and aluminum double-structured layers were prepared by thermal evaporation on quartz glasses and their surface microstructure, light scattering properties, and thermal stability were investigated. Results showed that the highly submicro-textured Ag/Al composite films prepared at low substrate temperatures used as back reflectors not only can enhance the light scattering and have good thermal stability, but also have good adhesion properties. In addition, their fabrication is low cost and readily carried out. 相似文献
998.
Cholesteric liquid crystal displays (Ch-LCDs) have potential as screens in portable readers. In the present study, it is demonstrated that a Ch-LCD can be driven by a thermal process at a temperature of 90 °C. At a suitable temperature, the texture of the cholesteric liquid crystal will be transfrred from planar to focal conic. The experimental results show that the reflectance of a Ch-LCD is influenced by texture after the thermal process. After thermal treatment at 90 °C, the periodicity was reduced from 63 nm to 55 nm. A chain tilting angle of ∼29° was estimated. 相似文献
999.
Comparing with physical and chemical methods, green synthesis techniques are emerging as facile and eco-friendly methods for the synthesis of silver nanoparticles. In this work, we demonstrated the biological synthesis of silver nanoparticles by the reduction of silver ions using kiwifruit juice as the reducing and stabilizing reagent. From the evidence of ultraviolet-visible spectroscopy and transmission electron microscopy, different sizes of silver nanoparticles were formed when the juice volume, reaction temperature, and reaction time were altered with respect to 0.01% silver acetate solution. The synthesized silver nanoparticles were stable for more than 1 month. Transmission electron microscopy studies showed the silver nanoparticles synthesized in room temperature have the diameters in the range of 5–25 nm. The proposed synthesis method is green and low cost, and the synthesized silver nanoparticles have potential bioanalytical applications. 相似文献
1000.
Molecular dynamics simulation of polyhedron analysis of Cu–Ag alloy under rapid quenching conditions
《Physics letters. A》2014,378(30-31):2151-2156
In this study, the formation mechanism of polyhedron clusters in Cu50Ag50 binary alloy system consisting of 50 000 atoms has been investigated by using molecular dynamics simulations based on embedded atom method (EAM) during the rapid cooling processes. The cluster-type index method (CTIM) has been used to describe the evaluation properties of clusters and the structural development has been investigated by using radial distribution function (RDF). The simulation results show that the amorphous phase is formed by the main bonded pairs of 1551, 1541 and 1431 in the system, and ideal icosahedral (icos) cluster (12 0 12 0) and other basic polyhedron clusters, such as defective icos, Frank–Kasper, Bernal polyhedron, play a critical role under the rapid cooling conditions. The results of our simulations that have been disclosed show that high cooling rate favors the icos and defective icos clusters for model alloy system. 相似文献