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Engineering the Magnetic Dipolar Interactions in 3D Binary Supracrystals Via Mesoscale Alloying 下载免费PDF全文
Zhijie Yang Jingjing Wei Pierre Bonville Marie‐Paule Pileni 《Advanced functional materials》2015,25(30):4908-4915
Inspired by metallic alloys in atomic solids, two distinct metallic nanoparticles are used, considered as “artificial metal atoms,” to engineer ordered binary nanoparticle alloys at the mesoscale, called binary supracrystals. Here, ferromagnetic 7.2 nm Co nanoparticles are used as large “A” site particles, while either ferromagnetic 4.6 nm Co or nonmagnetic 4.0 nm Ag nanoparticles are used as small “B” site particles to fabricate long‐range ordered binary supracrystals with a stoichiometry of AB2 and AB13. The interparticle distances between 7.2 nm Co nanoparticles within the Co/Ag binary supracrystals can be tuned by a control of crystal structure from AB2 (CoAg2) to AB13 (CoAg13). A decrease of magnetic coupling between Co nanoparticles is observed as the Co–Co interparticle distance increases. Furthermore, by alloying 7.2 and 4.6 nm Co nanoparticles to form AB2 (CoCo2) binary supracrystals, a collective magnetic behavior of these two particle types, due to the dipolar interaction, is evidenced by observing a single peak in the zero‐field‐cooled magnetization curve. Compared with the CoAg2 binary supracrystals, a spin orientation effect in sublattice that reduces the dipolar interactions in the supracrystals is uncovered in CoCo2 binary supracrystals. 相似文献
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Yanfen Wan Hervé Portalès Nicolas Goubet Alain Mermet Marie-Paule Pileni 《Nano Research》2013,6(8):611-618
A colloidal solution of 5 nm Au tetradecanethiol-coated nanoparticles is syn-thesized. After fast evaporation of one drop, ordered monolayers both composed of single domain and polycrystalline nanocrystals are obtained. On increasing the amount of materials and the evaporation time, nanocrystal films with irregular outlines are produced together with close-packed 3D superlattices exhibiting a truncated-tetrahedral shape. Using low-frequency micro-Raman scattering spectroscopy and electron microscopy the building block nanocrystallinity is characterized. Spontaneous nanocrystallinity segregation is revealed: the truncated-tetrahedral supracrystals are shown to mainly contain single domain building blocks while the supracrystalline films are composed of a mixture of single domain and polycrystalline nanocrystals. This observation points out the correlation between the nanocrystallinity segregation involved in the growth of the nanocrystal superlattices and their morphology. 相似文献
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Danny Haubold Annett Reichhelm Alexander Weiz Lars Borchardt Christoph Ziegler Lydia Bahrig Stefan Kaskel Michael Ruck Alexander Eychmüller 《Advanced functional materials》2016,26(27):4890-4895
Supracrystals are highly symmetrical ordered superstructures built up from nanoparticles (NPs) via self‐assembly. While the NP assembly has been intensively investigated, the formation mechanism is still not understood. To shed some light onto the formation mechanism, one of the most common supracrystal morphologies, the trigonal structures, as a model system is being used to investigate the formation process in solution. To explain the formation of the trigonal structures and determining the size of the supracrystal seeds formed in solution, the concept of substrate‐affected growth is introduced. Furthermore, the influence of the NP concentration on the seed size is shown and our investigations from Ag toward Au are extended. 相似文献
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Cong Yan Imad Arfaoui Nicolas Goubet Marie‐Paule Pileni 《Advanced functional materials》2013,23(18):2315-2321
The elastic properties of highly ordered three‐dimensional colloidal crystals of gold nanocrystals (called supracrystals) are reported. This study is based on the simultaneous growth of two kinds of gold nanocrystal supracrystals that range in size from 5 nm to 8 nm: interfacial supracrystals and precipitated supracrystals. The elastic properties are deduced from nanoindentation measurements performed with an atomic force microscope. The Young's modulus of the interfacial supracrystals, which grow layer‐by‐layer and form well‐defined films, is compared to that of precipitated supracrystals, which are produced by homogeneous growth in solution. For the precipitated supracrystals, characterized by a thickness larger than 1 μm, the Oliver and Pharr model is used to determine the elastic moduli, which are in the gigapascal range and decrease with increasing nanocrystal size. For the interfacial supracrystals, with 300 nm average thickness, a second model (plate model) is applied in addition to the Oliver and Pharr model. These two models confirm independently that the interfacial films are very soft with Young's modulus in the range of 80–240 MPa. This result reveals a totally new feature of nanocrystal solids, never emphasized before. It is shown that these changes in the Young's modulus are related to the supracrystal growth mechanism. 相似文献
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