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具有核/壳结构的复合纳米材料兼有外壳层和内核材料的性能,由于其结构和组成能够在nm尺度上进行设计和剪裁,因而具有许多独特的光、电、磁、催化等物理与化学性质。简要介绍了实验室在过渡金属纳米复合高频软磁材料研究方面的最新进展,内容包括:绝缘壳层(如SiO2、Al2O3、C-SiO2等)复合材料,能显著改善过渡金属纳米颗粒的热温度性,有效防止氧化和团聚,具有饱和磁化强度高、高频软磁性能优异的特点;半导体壳层(如ZnO)复合材料,研究了材料的光致发光性能,观测到在ZnO材料中较少出现的700nm发光峰;螺旋碳纳米管与Fe组成的复合材料,实验结果表明该复合材料具有良好的高频吸波性能,有望成为新一代轻质高频吸波材料。 相似文献
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Sen W. Kwok Stephen A. Morin Bobak Mosadegh Ju‐Hee So Robert F. Shepherd Ramses V. Martinez Barbara Smith Felice C. Simeone Adam A. Stokes George M. Whitesides 《Advanced functional materials》2014,24(15):2180-2187
This paper describes the modular magnetic assembly of reconfigurable, pneumatically actuated robots composed of soft and hard components and materials. The soft components of these hybrid robots are actuators fabricated from silicone elastomers using soft lithography, and the hard components are acrylonitrile–butadiene–styrene (ABS) structures made using 3D printing. Neodymium–iron–boron (NdFeB) ring magnets are embedded in these components to make and maintain the connections between components. The reversibility of these magnetic connections allows the rapid reconfiguration of these robots using components made of different materials (soft and hard) that also have different sizes, structures, and functions; in addition, it accelerates the testing of new designs, the exploration of new capabilities, and the repair or replacement of damaged parts. This method of assembling soft actuators to build soft machines addresses some limitations associated with using soft lithography for the direct molding of complex 3D pneumatic networks. Combining the self‐aligning property of magnets with pneumatic control makes it possible for a teleoperator to modify the structures and capabilities of these robots readily in response to the requirements of different tasks. 相似文献
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The latest three-dimensional (3D) chip-stacking technology requires the repeated stacking of additional layers without remelting
the joints that have been formed at lower levels of the stack. This can be achieved by transient liquid-phase (TLP) bonding
whereby intermetallic joints can be formed at a lower temperature and withstand subsequent higher-temperature processes. In
order to develop a robust low-temperature Au/In TLP bonding process during which all solder is transformed into intermetallic
compounds, we studied the Au/In reaction at different temperatures. It was shown that the formation kinetics of intermetallic
compounds is diffusion controlled, and that the activation energy of Au/In reaction is temperature dependent, being 0.46 eV
and 0.23 eV for temperatures above and below 150°C, respectively. Moreover, a thin Ti layer between Au and In was found to
be an effective diffusion barrier at low temperature, while it did not inhibit joint formation at elevated temperatures during
flip-chip bonding. This allowed us to control the intermetallic formation during the distinct stages of the TLP bonding process.
In addition, a minimal indium thickness of 0.5 μm is required in order to enable TLP bonding. Finally, Au/In TLP joints of ∅40 μm to 60 μm were successfully fabricated at 180°C with very small solder volume (1 μm thickness). 相似文献
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Enhanced Nucleation of Vortices in Soft Magnetic Materials Prepared by Silica Nanosphere Lithography
Norbert Martin Nadja‐Carola Bigall Ingolf Mönch Thomas Gemming Alexander Eychmüller Roland Mattheis Rudolf Schäfer Ludwig Schultz Jeffrey McCord 《Advanced functional materials》2011,21(5):891-896
Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO2‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices. 相似文献
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Zhengchen Wu Ke Pei Linshen Xing Xuefeng Yu Wenbin You Renchao Che 《Advanced functional materials》2019,29(28)
The microwave absorption (MA) performance of carbon materials is severely hindered by their drawbacks of lacking magnetic loss ability and mismatched electromagnetic impedance. In this work, utilizing sustainable biomass kapok as a template, the hierarchically tubular C/Co nanoparticle composite is rationally constructed to acquire the enhanced MA performance for the first time. The fruit‐tree‐like hierarchical structure is composed from a “trunk” of kapok‐derived carbon microtubes, a “branch” of entangled carbon nanotubes, and “fruit” of Co nanoparticles embedded in the nanotubes. Such a hierarchically tubular structure offers the composite: i) a submillimeter‐scale 3D magnetic coupling network and reinforced magnetic loss ability, ii) a hierarchical dielectric carbon network, iii) better matched impedance, confirmed by the off‐axis electron holography and micromagnetic simulation. Accordingly, the as‐prepared hierarchically tubular carbon composite demonstrates impressive MA performance, with a maximum reflection loss of as much as ?52.3 dB and a broad absorption bandwidth of 5.1 GHz. These encouraging achievements light the way to the development of the hierarchical microstructure of magnetic absorbents. 相似文献
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Benjamin J. Blaiszik Marta Baginska Scott R. White Nancy R. Sottos 《Advanced functional materials》2010,20(20):3547-3554
Autonomic self‐healing of interfacial damage in a model single‐fiber composite is achieved through sequestration of ca. 1.5 μm diameter dicyclopentadiene (DCPD) healing‐agent‐filled capsules and recrystallized Grubbs’ catalyst to the fiber/matrix interface. When damage initiates at the fiber/matrix interface, the capsules on the fiber surface rupture, and healing agent is released into the crack plane where it contacts the catalyst, initiating polymerization. A protocol for characterizing the efficiency of interfacial healing for the single‐fiber system is established. Interfacial shear strength (IFSS), a measure of the bond strength between the fiber and matrix, is evaluated for microbond specimens consisting of a single self‐healing functionalized fiber embedded in a microdroplet of epoxy. The initial (virgin) IFSS is equivalent or enhanced by the addition of capsules and catalyst to the interface and up to 44% average recovery of IFSS is achieved in self‐healing samples after full interfacial debonding. Examination of the fracture interfaces by scanning electron microscopy reveals further evidence of a polyDCPD film in self‐healing samples. Recovery of IFSS is dictated by the bond strength of polyDCPD to the surrounding epoxy matrix. 相似文献
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Significant Strain‐Induced Orbital Reconstruction and Strong Interfacial Magnetism in TiNi(Nb)/Ferromagnet/Oxide Heterostructures via Oxygen Manipulation 下载免费PDF全文
Chun Feng Shiru Wang Li Yin Xujing Li Mingke Yao Feng Yang Xiaolei Tang Lei Wang Wenbo Mi Guanghua Yu 《Advanced functional materials》2018,28(37)
Dynamical manipulation of oxygen ion (O2?) at metal/oxide heterointerfaces is widely demonstrated to tailor numerous physical and chemical properties and facilitate creating novel functionalities significantly. The traditional works mainly focus on electric control of O2? dynamical behavior and related interface characteristics. Here, an alternative strategy is reported to modulate O2? transport and interfacial magnetism via a significant strain induced by shape memory effect, which is different from the conventional magnetoelastic coupling mechanism. By driving the martensite to austenite transition in TiNi(Nb) shape memory alloy substrates, a significant and tunable strain is exerted on Pt/Co/MgO heterostructure, which promotes interfacial O2? migration in a nonvolatile manner. The O2? migration induces an orbital reconstruction of Co to tune the orbital magnetism noticeably, which strengthens the interfacial magnetic anisotropy energy by two times to a striking value of 0.95 erg cm?2. Besides, the overall magnetic anisotropy is broadly tunable from in‐plane to perpendicular direction by an elaborate strain engineering with changing Co thickness. This work develops a nonelectrical oxygen manipulation for tailoring ion‐controlled interfacial properties universally and also clarifies the magnetoionic coupling origin for enriching the oxygen‐related orbital physics and functional device applications. 相似文献
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Wenzhan Xu Tao Zhu Yongrui Yang Luyao Zheng Lei Liu Xiong Gong 《Advanced functional materials》2020,30(30)
Perovskite photovoltaics have drawn great attention in both academic and industrial sectors in the past decade. To date, impressive device performance has been achieved in state‐of‐the‐art device architectures through morphological manipulation and generic interface engineering. In this study, enhanced device performance of perovskite photovoltaics by magnetic field‐aligned CH3NH3PbI3‐mixed Fe3O4 magnetic nanoparticles (CH3NH3PbI3:Fe3O4) composite thin films is reported. It is found that magnetic field‐aligned CH3NH3PbI3:Fe3O4 composite thin films possess superior film morphology, boosted and balanced charge carrier mobility, and suppressed trap density. Moreover, perovskite photovoltaics by magnetic field‐aligned CH3NH3PbI3:Fe3O4 composite thin films exhibit suppressed charge carrier recombination and shorter charge carrier extraction time. As a result, perovskite solar cells by magnetic field‐aligned CH3NH3PbI3:Fe3O4 composite thin films exhibit 20.23% power conversion efficiency with significantly reduced photocurrent hysteresis. Moreover, perovskite photodetectors by magnetic field‐aligned CH3NH3PbI3:Fe3O4 composite thin films exhibit a photoresponsivity of 858 mA W?1, a photodetectivity over 1013 Jones (1 Jones = 1 cm Hz1/2 W?1) and a linear dynamic range over 160 dB at room temperature. All these device performance parameters are significantly better than those by pristine CH3NH3PbI3 thin film. Thus, these studies provide a facile way to boost device performance of perovskite photovoltaics. 相似文献
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Roland Fuhrer Christoph M. Schumacher Martin Zeltner Wendelin J. Stark 《Advanced functional materials》2013,23(31):3845-3849
The combination of force and flexibility enables controlled and soft movements. In sharp contrast, presently used machines are solid and mostly based on stiff driveshafts or cog wheels. Magnetic elastomers are realized through dispersion of small particles in polymer matrices and have attracted significant interest as soft actuators for controlled movement or conveying and are particularly attractive candidates for magnetic pump applications. At present, low magnetic particle loading and thus limited actuator strength have restricted the application of such materials. Here, the direct incorporation of metal microparticles into a very soft and flexible silicone and its application as an ultra‐flexible, yet strong magnetic tube, is described. Because metals have a far higher saturation magnetization and higher density than oxides, the resulting increased force/volume ratio afforded significantly stronger magnetic actuators with high mechanical stability, flexibility, and shape memory. Elliptical inner diameter shape of the tubing allowed a very efficient contraction of the tube by applying an external magnetic field. The combination of magnetic silicone tubes and a magnetic field generating device results in a magnetic peristaltic pump. 相似文献
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Techniques and Apparatus for Measuring Rotational Core Losses of Soft Magnetic Materials 总被引:1,自引:0,他引:1
In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years. 相似文献
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Enhanced Collective Magnetic Properties Induced by the Controlled Assembly of Iron Oxide Nanoparticles in Chains 下载免费PDF全文
Delphine Toulemon Mircea V. Rastei David Schmool José Sáiz Garitaonandia Luis Lezama Xavier Cattoën Sylvie Bégin‐Colin Benoit P. Pichon 《Advanced functional materials》2016,26(15):2454-2462
1D assemblies of magnetic nanoparticles are of great potential for designing novel nanostructured materials with enhanced collective magnetic properties. In that challenging context, a new assembly strategy is presented to prepare chains of magnetic nanoparticles that are well‐defined in structure and in spatial arrangement. The 1D assembly of iron oxide nanoparticles onto a substrate is controlled using “click” chemistry under an external magnetic field. Co‐aligned single nanoparticle chains separated by regular distances can be obtained by this strategy. The intrinsic high uniaxial anisotropy results in a strong enhancement of magnetic collective properties in comparison to 2D monolayers or isolated nanoparticles. In contrast to the intensively studied bundle chains of nanoparticles, the finely tuned chain structure reported here allows evidencing a first order intrachain dipolar interaction and a second order interchain magnetic coupling. This study offers new insights into the collective magnetic properties of highly anisotropic particulate assemblies which have been investigated by combining superconducting quantum interference device magnetometry, magnetic force microscopy, and ferromagnetic resonance. 相似文献
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Kazim K. Moncal Hemanth Gudapati Kevin P. Godzik Dong N. Heo Youngnam Kang Elias Rizk Dino J. Ravnic Hwabok Wee David F. Pepley Veli Ozbolat Gregory S. Lewis Jason Z. Moore Ryan R. Driskell Thomas D. Samson Ibrahim T. Ozbolat 《Advanced functional materials》2021,31(29):2010858
Reconstruction of complex craniomaxillofacial (CMF) defects is challenging due to the highly organized layering of multiple tissue types. Such compartmentalization necessitates the precise and effective use of cells and other biologics to recapitulate the native tissue anatomy. In this study, intra-operative bioprinting (IOB) of different CMF tissues, including bone, skin, and composite (hard/soft) tissues, is demonstrated directly on rats in a surgical setting. A novel extrudable osteogenic hard tissue ink is introduced, which induced substantial bone regeneration, with ≈80% bone coverage area of calvarial defects in 6 weeks. Using droplet-based bioprinting, the soft tissue ink accelerated the reconstruction of full-thickness skin defects and facilitated up to 60% wound closure in 6 days. Most importantly, the use of a hybrid IOB approach is unveiled to reconstitute hard/soft composite tissues in a stratified arrangement with controlled spatial bioink deposition conforming the shape of a new composite defect model, which resulted in ≈80% skin wound closure in 10 days and 50% bone coverage area at Week 6. The presented approach will be absolutely unique in the clinical realm of CMF defects and will have a significant impact on translating bioprinting technologies into the clinic in the future. 相似文献
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N. Martin N. C. Bigall I. Mönch T. Gemming A. Eychmüller R. Mattheis R. Schäfer L. Schultz J. McCord 《Advanced functional materials》2011,21(5):801-801
Magnetic vortices show promise as data storage structures, however the vortex formation process imposes a lower limit on the element’s size. In this article a technique is presented, which application increases the probability of nucleating of magnetic vortices in sub‐micrometer sized soft magnetic thin film elements. By tailoring the edge geometry of the elements, the symmetry of their magnetic configuration is broken in a manner which favors vortex nucleation. Micromagnetic simulations are presented, which demonstrate this effect in soft‐magnetic disks with beveled edges. The favored edge geometry is realized by applying nanosphere lithography directly on top of a ferromagnetic thin film material. In this process, the film is masked with a self assembled monolayer of SiO2‐nanospheres and subsequently ion‐etched. The resulting magnetic reversal loops show that in both magnetically isolated as well as in closely packed arrays of beveled disks, vortex formation takes place. The technique presented facilitates the vortex formation even in closely packed and small elements. The lowering of the minimum critical diameter for vortex formation enables a significant increase of data storage density in devices based on magnetic vortices. 相似文献