Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Chang, C. T.; Su, Shih-Chieh; Chang, Tsun-Hsu; Chang, Ching‐Ray

doi:10.1038/s41598-021-82590-w

Cited by 5 publications

(3 citation statements)

References 31 publications

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“…The pattern of susceptibility-frequency change in the Ni and Fe sample is consistent with the of results of R.F. Jardim et al [20] and Ching-Ray Chang et al [21] observed on Ni and nano magnetite powder sample.…”

Section: Calibration Of the Ac Susceptometer And Measurement Of Stand...supporting

confidence: 90%

A versatile and cost-effective automation of an AC susceptometer using Virtual Instruments and Arduino-Uno microcontroller

Borgohain

2021

J. Inst.

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A LabVIEWTM based VIRTUAL INSTRUMENT (VI) system is designed with the aid of an Arduino-Uno microcontroller, which is used as a data acquisition system for collecting data from an AC magnetic susceptometer operating in the range of 10 Hz to 10 kHz. The magnetic susceptometer system was indigenously built using standard modules/components and is capable of measuring AC magnetic susceptibility from room temperature down to 100 K. The proposed VI can have diverse applications and may be modified according to the user requirements. Herein, we have decided to focus its applicability on the automation of an AC susceptometer integrated with an inexpensive signal processing unit comprising an AD630-based lock-in-amplifier and an ICL8038-based signal generator. Data from the lock-in- amplifier, the signal generator, and the temperature sensor are interfaced to a computer via an Arduino-Uno microcontroller. A program (VI) developed using LabVIEW is used to acquire and record in a PC the data from the AC magnetic susceptometer.

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Section: Calibration Of the Ac Susceptometer And Measurement Of Stand...supporting

confidence: 90%

A versatile and cost-effective automation of an AC susceptometer using Virtual Instruments and Arduino-Uno microcontroller

Borgohain

2021

J. Inst.

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“…In this case, it is not clear whether the magnetic particles move themselves or move by the shape change of the magnetic elastomer. The relative magnetic susceptibility of carbonyl iron is 600-fold higher than that of epoxy resin . It can be considered that the magnetic effect of resin can be neglected in this experiment.…”

Section: Methodsmentioning

confidence: 99%

“…The relative magnetic susceptibility of carbonyl iron is 600-fold higher than that of epoxy resin. 33 It can be considered that the magnetic effect of resin can be neglected in this experiment. An electromagnet (5201 horizontal projected field, GMW) was used to generate magnetic fields using a bipolar power supply (BOP20-20DL, KEPCO) while monitoring the output current with a digital multimeter (Keithley 2100).…”

Section: Methodsmentioning

confidence: 99%

In Situ Observation of the Movement of Magnetic Particles in Polyurethane Elastomer Densely Packed Magnetic Particles Using Synchrotron Radiation X-ray Computed Tomography

et al. 2022

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In situ observation of the migration and structure formation of magnetic particles in polyurethane elastomers was carried out by X-ray computed tomography using synchrotron radiation. The mean diameter of the magnetic particles was 7.0 μm, and the volume fraction was ϕ= 0.24 at its maximum. The exposure time was 100 ms/frame, and the pixel size was 0.458 μm/ pixel. The orientation angle and the volume fraction of the maximum aggregate were analyzed using commercial software for image analysis. The orientation angle for magnetic elastomers with ϕ = 0.24 was approximately 55°at 0 mT and decreased remarkably with the magnetic field. At magnetic fields above 150 mT, the orientation angle gradually decreased with the field and showed a constant value of 38°at 300 mT, suggesting that magnetic particles move and form a chain-like structure although the chains do not align perfectly in the direction of the magnetic field. On the other hand, the volume fraction of the maximum aggregate was constant at magnetic fields below 100 mT, and it significantly increased with the field, indicating that magnetic particles were connected to each other and developed into a macroscopic structure with anisotropy. Dynamic viscoelastic measurements revealed that the storage modulus of the magnetic elastomers cannot be simply scaled by the orientation angle. It was also found that the volume fraction of the maximum aggregate is a good parameter for explaining the huge increase in the storage modulus. The dynamic movement of magnetic particles when a magnetic field of 300 mT was switched on and off was also successfully observed. When the field was switched on, magnetic particles connected instantly and their aggregates were rapidly elongated in the direction of the magnetic field. When the field was switched off, some of the connections between aggregates were broken; however, most of the aggregates did not return to the original position even 5 min after being switched off.

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Electromagnetic composites: From effective medium theories to metamaterials

Qin

Peng

Estévez

et al. 2022

Journal of Applied Physics

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Electromagnetic (EM) composites have stimulated tremendous fundamental and practical interests owing to their flexible electromagnetic properties and extensive potential engineering applications. Hence, it is necessary to systematically understand the physical mechanisms and design principles controlling EM composites. In this Tutorial, we first provide an overview of the basic theory of electromagnetism about electromagnetic constitutive parameters that can represent the electromagnetic properties of materials. We show how this corpus allows a consistent construction of effective medium theories and allows for numerical simulation of EM composites to deal with structure–property relationships. We then discuss the influence of spatial dispersion of shaped inclusions in the material medium on the EM properties of composites, which has not been systematically illustrated in the context of this interdisciplinary topic. Next, artificial composites or metamaterials with peculiar properties not readily available in nature are highlighted with particular emphasis on the control of the EM interaction with composites. We conclude by discussing appropriate methods of electromagnetic measurement and practical aspects for implementing composites for specific applications are described. Overall, this Tutorial will serve the purpose of introducing the basics and applications of electromagnetic composites to newcomers in this field. It is also anticipated that researchers from different backgrounds including materials science, optics, and electrical engineering can communicate to each other with the same language when dealing with this interdisciplinary subject and further push forward this advancement from fundamental science to technological applications.

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Frequency-induced negative magnetic susceptibility in epoxy/magnetite nanocomposites

Cited by 5 publications

References 31 publications

A versatile and cost-effective automation of an AC susceptometer using Virtual Instruments and Arduino-Uno microcontroller

A versatile and cost-effective automation of an AC susceptometer using Virtual Instruments and Arduino-Uno microcontroller

In Situ Observation of the Movement of Magnetic Particles in Polyurethane Elastomer Densely Packed Magnetic Particles Using Synchrotron Radiation X-ray Computed Tomography

Electromagnetic composites: From effective medium theories to metamaterials

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