Preparation and magnetic properties of monodisperse Permalloy hollow spheres

Lin, Chun-Rong; Hsieh, Ming-Hsiu; Siao, Yu-Jhan; Wang, Cheng Chien

doi:10.1063/1.2830229

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…Over the last decade, much effort has been devoted to studying submicro-/nano-size magnetic hollow spheres of metals (Co [25,29,30], Ni [23,25,31,32,33], and Fe [30]), intermetallic alloys (FePt [34], CoPt [35,36], and NiFe [37]) and metal oxides/ferrites (Co 3 O 4 [28], CoO [38], Ni [39], α-/γ-Fe 2 O 3 [40,41,42,43], CoFe 2 O 4 [44,45,46], and Fe 3 O 4 [9,10,26,47,48,49,50,51,52,53,54,55,56]). As a result, a number of preparation methods have been developed, such as the template-mediated approach [23,26,28,30,31,32,33,34,36,37,40,43,44,45,46,47,48,49,50,51,52], nanoscale Kirkendall effect [42,54], Ostwald ripening [25,53,…”

Section: Introductionmentioning

confidence: 99%

“…As a result, a number of preparation methods have been developed, such as the template-mediated approach [23,26,28,30,31,32,33,34,36,37,40,43,44,45,46,47,48,49,50,51,52], nanoscale Kirkendall effect [42,54], Ostwald ripening [25,53,55], galvanic replacement [35], and so on. Among them, the template-mediated approach is one of the most prevalent methods, and has been employed by many groups.…”

Section: Introductionmentioning

confidence: 99%

“…Among them, the template-mediated approach is one of the most prevalent methods, and has been employed by many groups. Templates can be mainly categorized into two types: hard templates (silica particles, polymer beads, and carbon spheres) [ 23 , 26 , 28 , 30 , 34 , 37 , 40 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ] and soft templates (emulsion droplets, supramolecular micelles/vesicles, and gas bubbles) [ 31 , 32 , 33 , 36 , 50 , 51 , 52 ]. Soft templates are often used in preparing nanometer-size hollow spheres, since the templates are usually in nanoscale sizes.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic and Optical Properties of Submicron-Size Hollow Spheres

Yoshikawa

Awaga

2010

Materials

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Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic and Optical Properties of Submicron-Size Hollow Spheres

Yoshikawa

Awaga

2010

Materials

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“…Hollow-structured metal materials have recently attracted considerable attention because of their potential applications in catalysis, bioseparation, medical diagnosis, and targeting drug delivery. , These hollow structures have low density, high specific surface, and large surface permeability without much sacrifice of mechanical and thermal stabilities, which is apparently superior to the solid counterparts. Hollow-structured Co materials are typically synthesized by using polystyrene (PS) sphere as the hard template. − For example, hollow Co spheres with a size of 660 nm and a shell thickness of 40 nm assembled by nanoparticles of about 15 nm were synthesized in liquid phase using PS as template .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Hollow Co Structures with Netlike Framework

Liu

Guo

et al. 2009

Langmuir

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Hollow Co structures with the size of 4-10 microm were fabricated by a simple solvothermal process using stearic acid as surfactant. Cobalt stearate formed at the initial stage and further self-assembled to micelles as a soft template. This precursor controlled the growth rate of Co crystal to form the primary nanorods attaching on the surface of the micelles. These nanorods then assembled into hollow Co spheres with a dense shell. Because of the acidic etching effect of stearic acid, however, the hollow Co spheres were further developed to Co nests constructed by netlike frameworks. Stearic acid acted as structure-directing and acidic etching agents in the formation of these novel hollow structures constructed by nanorods. The Co nests showed quite promising catalytic performance in hydrogenolysis of glycerol, demonstrating the potential application in heterogeneous catalysis.

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“…In this sample, while the ∼5 nm nanoparticles were small enough to exhibit superparamagnetism [6], the ∼35 nm nanoparticles were too large, leading to the hysteresis at 300 K. In comparison to the bulk, the coercive field at 300 K was higher than the reported unannealed Ni (3 mT) [126] and was also found to higher than when compared with electrospun Ni nanofibers. [125] However, it was similar to that reported for Ni 1−x Fe x nanoparticles with x=0.2 with diameters of 22 nm (10.5 mT) [127], and was twice of that reported for 18 nm diameter at x=0.1 nanoparticles (6 mT). [128] The lower right inset of Figure 4.…”

Section: Magnetic Studiessupporting

confidence: 86%

Synthesis of Magnetic Nanofibers for Their Potential Applications in Wireless Charging for Energy Efficient EVs

Nawaz¹

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There is a growing demand to find new materials for flux guiding applications in the inductive power transfer systems. The inductive power transfer system (IPT) in electric vehicles has gained importance due to advantages including safety, efficiency, flexibility, and user-friendliness. The potential of IPT systems in dynamic flux transfer on-road requires the flux concentrators to maximize flux transfer at minimum power losses. Ferrite materials are the most commonly used materials in the IPT cores for flux-transfer applications due to their reasonable susceptibility, high resistivity, and semi-conducting nature. Their high resistivity is advantageous to minimize eddy-current losses. However, there are certain drawbacks to their use, for example, they can still result in some eddy-current losses as their resistivity is not high enough, they are very brittle in nature and are difficult to be made in thin sheets or in arbitrary shapes, and they are very heavy that increases the vehicle mass and energy consumption. An ideal material for wireless charging applications should be thin, and flexible that can be made in arbitrary shapes with a reasonable susceptibility and high resistivity for wireless charging applications. This thesis aimed to investigate the preparation of bimetallic Ni1−xFex, semi-conducting MnFe2O4, and Sm3+ doped semi-conducting MnFe2−xSmxO4 nanofibers made by an electrospinning method for their potential applications in wireless charging. Ni1−xFex was selected because the bulk material shows a high permeability which is useful for flux-guiding, but it has a low resistivity. However, the preparation of thin Ni1−xFex nanofiber sheets can result in high resistivities in nanodimensions. The parameter x was studied by varying its value between 0.1-0.5 as Ni1−xFex show high susceptibility at x∼0.2, and high magnetic moment at x∼0.5. The characterizations showed the presence of Ni1−xFex nanoparticles formation within nanofibers for all the samples which can be advantageous to further increasing the resistivity and to reduce eddy-current losses. A bimodal particle size distribution was observed at x∼0.1, that became less bimodal at x∼0.2 and skewed with predominantly small nanoparticles at x∼0.5. Superparamagnetic behaviour was observed at x∼0.5 due to the formation of smaller nanoparticles. There was a systematic increase in the differential susceptibility with increasing x from 6 at x∼0.1 to 18 at x∼0.5. These results were encouraging for potential applications in wireless charging. Semiconducting MnFe2O4 nanofibers were made by electrospinning method because bulk material has high resistivity. The thermal processing of these nanofibers at 700◦C resulted in large polycrystalline nanoparticles whereas, the thermal processing at lower temperature 620◦C resulted in a mixture of small nanoparticles within these nanofibers. The presence of some single crystal nanorods was also seen in both samples. The high field magnetization was largest for the sample processed at higher temperature, i.e., 57% of the total magnetization value at 700◦C as compared to 46% obtained at low temperatures at 620◦C. However, one sample processed at 620◦C showed the complete formation of MnFe2O4 nanorods with the highest saturation magnetization to 76% of the total magnetization. These results are encouraging as the potential of nanorod synthesis can be useful in the flux guiding applications. Electrospun MnFe2−xSmxO4 nanofibers with Sm3+(x) doping were also made to observe the change in the structural and magnetic properties at x=0.06-0.25. The results showed the successful incorporation of Sm3+ in the crystal structure of MnFe2O4 at x≤0.2. Polycrystalline nanoparticles were seen at low fractions of x≤0.1 but more smaller nanoparticles were formed at x=0.2 and x=0.25. Superparamagnetic behaviour was observed at high fractions of x (x=0.2 and x=0.25). The saturation magnetization for x≤0.2 was largest for x=0.06. This study has provided a solid foundation for a more in-depth exploration of magnetic electrospun nanofiber sheets for future applications in wireless charging systems.

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Preparation and magnetic properties of monodisperse Permalloy hollow spheres

Cited by 4 publications

References 11 publications

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

Synthesis of Hollow Co Structures with Netlike Framework

Synthesis of Magnetic Nanofibers for Their Potential Applications in Wireless Charging for Energy Efficient EVs

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