Effect Of High Magnetic Field Research Articles

High magnetic field effects on transport coefficients in heavily doped n-type Mg2Si

In contrast to parabolic band model typically used in understanding electronic properties in general, thermoelectric and magneto-thermoelectric in particular, this study confirms non-parabolic band model results in better understanding of Seebeck coefficient and Nernst coefficient in the presence of magnetic field for Mg2Si. The magneto Seebeck coefficient was found significantly enhanced from its zero-field value for non-parabolic band model compared to parabolic band model for different electron concentrations in the range 0.6 - 12× 1025/m3 and at room temperature due to the high magnetic field slightly beyond |3|T, but not for others. In both cases, the Seebeck coefficient is enhanced as a result of the magnetic field. The result for Nernst coefficient shows increasing trend in high magnetic field in the range |3-9|T for parabolic band model while it is decreasing with magnetic field on average for non-parabolic band model except for few of them slowly increasing.

Magnetic-field-induced valence change in Eu(Co1−xNix)2P2 up to 60 T

The solid solution 122 compounds, $\mathrm{Eu}{({\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x})}_{2}{\mathrm{P}}_{2}$, show a valence transition between divalent state and intermediate valence states at Eu, which is firmly correlated to multiple degrees of freedom in the solid such as the isostructural transition between the collapsed tetragonal (cT) and uncollapsed tetragonal (ucT) structures, $3d$ magnetism, and the formation of P-P dimers. To gain insights into the correlated behavior, we investigate the effect of high magnetic fields on the samples of $x=0.4$ and 0.5 using magnetostriction and magnetization measurements up to 60 T. The samples are in the Eu valence-fluctuating regime, where the possible structural transition from cT to ucT may be induced by the Eu valence change under the magnetic fields. For both samples, magnetostriction smoothly increases with increasing magnetic fields. The behavior is in good agreement with the calculated results using the interconfigurational fluctuation (ICF) model that describes the Eu valence change. This indicates that $\mathrm{\ensuremath{\Delta}}L$ represents the change of the Eu valence state in these compounds. Magnetization curves for both compounds show good agreement with the ICF model at high magnetic fields. In contrast, in the low-magnetic-field region, magnetization curves do not agree with the ICF model. These results indicate that the Eu valence changes manifest themselves in the magnetization curves at high magnetic fields and that the magnetism of the $3d$ electrons manifests itself in the magnetization at low magnetic fields. Hence, we conclude that the valence change occurs within the Eu valence fluctuation regime coupled with the cT structure. Thereby, we believe that the transition to ucT structure, which is firmly coupled with the divalent Eu state, does not occur within the magnetic field range of the present study. Even higher magnetic fields or pulsed magnetic fields with slower pulse durations may induce such large state changes in the present material, which is triggered by the Eu valence change under high magnetic fields.

Effect of high intensity pulsed magnetic field (30 T) on microstructure and tribological properties of Ni-based coatings

Pulsed magnetic fields can improve ferromagnetic and paramagnetic materials by improving their stress structure, domain variation, phase structure distribution and grain size of both solid and molten metals. Therefore, we strengthened the Ni-based wear-resistant coating by using the high-intensity (30 T) pulsed magnetic field equipment independently developed by our research group. The results show that the magnetic domains appeared as sheet domains and showed sinusoidal distribution after pulsed magnetic field intensification. The crystal structure is improved, the residual compressive stress is increased and the tribological coefficient is decreased. This study provides a new perspective on the design of high-strength metal base coatings for various applications.

Effect of High Magnetic Field on Microstructure Evolution, Solute Distribution, and Crystallography in Directionally Solidified Cu–Ge Peritectic Alloy

Effect of High Magnetic Field on Microstructure Evolution, Solute Distribution, and Crystallography in Directionally Solidified Cu–Ge Peritectic Alloy

Preface

The 2022 8th International Forum on Manufacturing Technology and Engineering Materials (IFEMMT 2022) was successfully held on October 14th-16th, 2022 in Chongqing, China (virtual conference). IFEMMT 2022 brought together academics and experts in the field of Manufacturing Technology and Engineering Materials to a common forum, making it a great platform for people to share views and experiences in related areas.We were honored to have Prof. Xiansheng Ning from Shenyang Ligong University, China to serve as our General Conference Chair. The conference covered keynote speeches, oral presentations, and online Q&A discussion, attracting 150 individuals. Firstly, keynote speakers were each allocated 30-45 minutes to hold their speeches. Then in the oral presentations, the excellent papers selected were presented by their authors in sequence.During the conference, five sophisticated professors were invited to make keynote speeches. Among them, Prof. Vijay Kumar Thakur from Scotland’s Rural College delivered a keynote speech on Polymer Nanocomposites as Promising Materials for the Future. Polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. The combination of both the polymers and fillers provides enhanced properties depending on the type and nature of polymer matrices as well as fillers. Therefore, this presentation mainly discussed about the work on the synthesis and processing of polymer-based materials for advanced application. Additionally, Assoc. Prof. Xiao Lu from Shenyang Ligong University made a report on Structure Design of Defective Electrocatalysts and Effect of High Magnetic Field on Electrocatalysis Process. The report proposed a method to achieve high efficiency oxygen reduction reaction by regulating the defect structure of carbon materials and metal catalyst materials and put forward the preparation of catalyst materials under strong magnetic field and the influence of strong magnetic field on oxygen evolution reaction and oxygen reduction reaction process. Their excellent presentations had sparked heated discussion in the conference. Moreover, every participant praised this conference for disseminating insightful knowledge.After months of well preparation and hard work, the proceedings of IFEMMT 2022 covering a bunch of papers are smoothly published. These papers feature but are not limited to the following topics: Advanced Design Technology, Manufacturing Systems and Automation, New Materials and Advanced Materials, etc. All the papers have been checked through rigorous review and processes to meet the requirements of publication.We would like to express our heartfelt appreciation to all the keynote speakers, peer reviewers, and all the participants. Particularly, we would like to acknowledge the Journal of Physics: Conference Series, for the endeavor of all its colleagues in publishing this paper volume. We are sure that IFEMMT 2022 will contribute to not only scientific and engineering progress but also other new products and processes.The Committee of IFEMMT 2022List of Committee member is available in this Pdf.

Effects of high magnetic field on the reactive sintering process of Mn–Ga magnetic composites

This study focuses on the microstructure and magnetic properties of Mn-20at. %Ga composites prepared via high-energy ball milling and subsequent reactive sintering under a high magnetic field (HMF). XRD identified the ɛ-Mn3Ga, β-Mn0.85Ga0.15, and α-Mn phases, and their fractions determined the magnetic properties of the composites. The results revealed that HMF enhanced the fractions of both ɛ-Mn3Ga and β-Mn0.85Ga0.15 phases and decreased the fraction of α-Mn. The magnetic-field-induced enhancement effect on the reaction was mainly due to a decrease in the activation energy, which mainly affected the phase reaction at the initial stages. However, a HMF of 9–12 T suppressed the atomic diffusion between Mn and Ga, reducing the reaction-enhancing effect of the magnetic field. Compared with zero-field annealing, the 3 T in-field annealing enhanced the remanence and coercivity of the composite by 44% and 16%, respectively. In contrast, the 12 T HMF decreased the remanence but increased the coercivity to its highest value. The coercivity of the 12 T in-field samples reaches 11.09 kOe after 8 h of in-field annealing. After the in-field annealing, subsequent zero-field annealing for an appropriate duration may further increase the remanence and energy product. Enhancing the in-field annealing temperature up to 400 °C may increase the coercivity but decrease the remanence considerably.

High static magnetic field-assisted synthesis of Mn-doped ZnO diluted magnetic semiconductor via the hydrothermal method

ABSTRACT The magnetic field-assisted approach had been applied in the synthesis of Mn-doped ZnO diluted magnetic semiconductor via the hydrothermal method. The effect of high static magnetic field (HSMF) on the structures, morphologies and magnetic properties of the samples were characterised. X-ray diffraction and X-ray photoelectron analysis revealed that Mn ions had been doped in the hexagonal wurtzite ZnO and there were no any other detectable phases observed. Energy dispersive spectroscopy revealed that the content ratio of Zn to Mn was about 19:1. In addition, transmission electron microscopy and high-resolution transmission electron microscopy studies confirmed that Zn0.95Mn0.05O was nanorods in shape, and the growth rate of the nanorod was obviously restrained. While more oxygen vacancies (V O) had been introduced with increasing the magnetic flux density. Finally, magnetisation measurements implied that all of the Zn0.95Mn0.05O samples were room-temperature ferromagnetism and their magnetism was improved by the HSMF.

Electrical Treeing and Its Suppression Method of SiR in High Magnetic Field

This paper investigates the effects of high magnetic field on electrical treeing of silicone rubber (SiR). Experimental results show that electrical trees are more easily to be initiated and spread further along the direction of electric field under the effects of high magnetic field. When the direction of high magnetic field is perpendicular to that of electric field, magnetic field with higher magnetic flux density also results in larger accumulated damage area. Splitting of energy band structure and changes in polarization characteristics result in a lower interface barrier and more serious partial discharge, thus causing the weakened resistance to electrical treeing in high magnetic field. Based on the insulation degradation mechanism, SiR was modified by adding ferroferric oxide (Fe3O4) nanoparticles to improve its insulation performance in high magnetic field. Moderate addition amount of Fe3O4 nanoparticles is proved to be able to suppress electrical treeing in high magnetic field by forming quantum dots, modifying polarization properties and partial discharge behavior. Excessive addition of Fe3O4 nanoparticles has negative effects on suppressing electrical treeing due to the magnetization of the nanocomposites.

Effects of gradient high-field static magnetic fields on diabetic mice.

Although 9.4 T magnetic resonance imaging (MRI) has been tested in healthy volunteers, its safety in diabetic patients is unclear. Furthermore, the effects of high static magnetic fields (SMFs), especially gradient vs. uniform fields, have not been investigated in diabetics. Here, we investigated the consequences of exposure to 1.0-9.4 T high SMFs of different gradients (>10 T/m vs. 0-10 T/m) on type 1 diabetic (T1D) and type 2 diabetic (T2D) mice. We found that 14 h of prolonged treatment of gradient (as high as 55.5 T/m) high SMFs (1.0-8.6 T) had negative effects on T1D and T2D mice, including spleen, hepatic, and renal tissue impairment and elevated glycosylated serum protein, blood glucose, inflammation, and anxiety, while 9.4 T quasi-uniform SMFs at 0-10 T/m did not induce the same effects. In regular T1D mice (blood glucose ≥16.7 mmol/L), the >10 T/m gradient high SMFs increased malondialdehyde ( P<0.01) and decreased superoxide dismutase ( P<0.05). However, in the severe T1D mice (blood glucose ≥30.0 mmol/L), the >10 T/m gradient high SMFs significantly increased tissue damage and reduced survival rate. In vitro cellular studies showed that gradient high SMFs increased cellular reactive oxygen species and apoptosis and reduced MS-1 cell number and proliferation. Therefore, this study showed that prolonged exposure to high-field (1.0-8.6 T) >10 T/m gradient SMFs (35-1 380 times higher than that of current clinical MRI) can have negative effects on diabetic mice, especially mice with severe T1D, whereas 9.4 T high SMFs at 0-10 T/m did not produce the same effects, providing important information for the future development and clinical application of SMFs, especially high-field MRI.

1-2​T static magnetic field combined with Ferumoxytol prevent unloading-induced bone loss by regulating iron metabolism in osteoclastogenesis.

With the deepening of magnetic biomedical effects and electromagnetic technology, some medical instruments based on static magnetic field (SMF) have been used in orthopedic-related diseases treatment. Studies have shown SMF could combat osteoporosis by regulating the differentiation of mesenchymal stem cells (MSCs), osteoblast and osteoclast. With the development of nanotechnology, iron oxide nanoparticles (IONPs) have been reported to regulate the process of bone anabolism. As for SMF combined with IONPs, studies indicated osteogenic differentiation of MSCs were promoted by the combination of SMF and IONPs. However, there are few reports on the effects of SMF combined with IONPs on osteoclast. Herein, the purpose of this study was to investigate the effects of high static magnetic field (HiSMF) combined with IONPs on unloading-induced bone loss in vivo and osteoclastic formation in vitro, and elucidated the potential molecular mechanisms. In vivo, C57BL/6​J male mice were unloaded via tail suspension or housed normally. The hindlimb of mice were fixed and exposed to 1-2​T SMF for 1​h every day, 10​mg/kg of Ferumoxytol or saline were injected by tail vein once a week, last for 4 weeks. Bone microstructure, mechanical properties, and osteoclastogenesis were examined respectively. In vitro, the RAW264.7​cells were used to assess the effects of 1-2​T SMF combined with IONPs in osteoclastogenesis. The iron content was detected by atomic absorption spectrometry and Prussian blue staining. DCFH-DA and MitoSOX™ fluorescence staining were used to assess oxidative stress levels. NF-κB and MAPK signaling pathways were examined by western blot assay. In vivo, the results showed 1-2​T SMF and IONPs prevented the damage to bone microstructure and improved the mechanical properties, diminished the number of osteoclasts in unloaded mice, 1-2​T SMF combined with IONPs was found more effective. The iron content in the liver and spleen was reduced by the combination of 1-2​T SMF and IONPs, enhancing iron levels in the femur. In vitro, osteoclast formation was inhibited by 1-2​T SMF and IONPs treatment, and 1-2​T SMF combined with IONPs had a more pronounced effect. Moreover, iron uptake of IONPs in osteoclast was reduced to 1-2​T SMF exposure. Oxidative stress levels were decreased in osteoclast differentiation under 1-2​T SMF combined with IONPs treatment. Molecularly, the expression of NF-κB and MAPK signaling pathways were inhibited under 1-2​T SMF combined with IONPs in osteoclastogenesis. Synthetically, our research illustrated 1-2​T SMF combined with IONPs prevented unloading-induced bone loss by regulating iron metabolism in osteoclastogenesis.Translational potential of this article: As a non-invasive alternative therapy, some medical instruments based on SMF have been used for orthopedic-related diseases treatment for their portability, cheapness and safety. Ferumoxytol (Feraheme™), the first FDA-approved IONP drug for the treatment of iron deficiency anemia, has been also adapted in translational research for osteoporosis. Based on the above-mentioned two points, we found the synergistic effects of SMF and Ferumoxytol for treatment of experimental osteoporosis. These results show translational potentials for clinical application.

Magnetic and Electric Field Dependent Charge Transfer in Perovskite/Graphene Field Effect Transistors

AbstractStable all‐inorganic CsPbX3 perovskite nanocrystals (PNCs) with high optical yield can be used in combination with graphene as photon sensors with high responsivity (up to 106 A W−1) in the VIS‐UV range. The performance of these perovskite/graphene field effect transistors (FET) is mediated by charge transfer processes at the perovskite – graphene interface. Here, the effects of high electric (up to 3000 kV cm−1) and magnetic (up to 60 T) fields applied perpendicular to the graphene plane on the charge transfer are reported. The authors demonstrate electric‐ and magnetic‐field dependent charge transfer and a slow (&gt;100 s) charge dynamics. Magneto‐transport experiments in constant (≈0.005 T s−1) and pulsed (≈1000 T s−1) magnetic fields reveal pronounced hysteresis effects in the transfer characteristics of the FET. A magnetic time is used to explain and model differences in device behavior under fast (pulsed) and slowly (continuous) changing magnetic fields. The understanding of the dynamics of the charge transfer in perovskite/graphene heterostructures developed here is relevant for exploitation of these hybrid systems in electronics and optoelectronics, including ultrasensitive photon detectors and FETs for metrology.

Mechanism of high magnetic field effect on the D03-L12 phase transition in Fe-Ga alloys

The effect of a high magnetic field (HMF) on phase transition and microstructure formation in Fe-Ga alloys with a Ga concentration of about 25 at.% has been investigated using experimental research and ab initio modeling. We found that the HMF of 25 T significantly accelerates the D03 to L12 transformation in the hyperstoichiometric Fe-27 %Ga alloy upon isothermal annealing at 475 °C. At the same time, the field has little effect on the transformation in the hypostoichiometric Fe-24 %Ga alloy. We have found that HMF does affect the kinetics of the transformation rather than the energy of the phases. We have shown that the effect of HMF is mainly associated with the ferromagnetic ordering of magnetic moments, which leads to lattice instability of the D03 phase and enhancement of the D03 → L12 transition due to the initiation of the barrierless mechanism.

Effect of High Magnetic Field in Combination with High-Temperature Tempering on Microstructures and Mechanical Properties of GCr15 Bearing Steel

The microstructures and mechanical properties of GCr15 bearing steel after high-temperature tempering with and without a 5 T high magnetic field (HMF) were investigated. It was found that the application of the HMF at the stage of high-temperature tempering slowed down the growth of the tempered sorbite (TS) structures, increased the density of the carbides, and reduced the carbide size and the volume fraction. XRD diffraction patterns showed that the HMF resulted in a higher dislocation density. Hardness testing indicated that the HMF led to an increase in the Vickers hardness in the tempered sample. It is inferred that the change in carbide size stems from the reduction in nucleation barrier in the HMF and the increase in dislocation density originates from the interaction between dislocations and carbides. Additionally, the decrease in diffusivity in the HMF also contributes to the reduction in the size of TS structures and the refinement of carbides. This work demonstrates that high-temperature tempering with an HMF can slow down the growth of TS microstructures in GCr15 bearing steel, control the carbide size, and improve Vickers hardness, which provides a new heat treatment method to regulate the microstructure and properties of GCr15 bearing steel.

Effects of High Magnetic Field on Partial Discharge and Dielectric Breakdown Behavior of Silicone Rubber

In this article, space charge and partial discharge (PD) behavior and the breakdown strength of silicone rubber under ac and dc voltages are tested in high magnetic field. In the case of ac voltage, the effects of high magnetic field on promoting air gap breakdown result in the decrease in PD inception voltage. Polarization of specimens with higher speed and lower air gap breakdown voltage result in the increase in PD frequency and eventually causes the decrease in breakdown strength. In the case of dc voltage, energy level splitting due to Zeeman effects results in lower interface barrier, considering both the increase in electron affinity and the increase in density deference between donor-like and acceptor-like surface traps. The decrease in interface barrier causes more space charge injection. The electric field distortion caused by local space charge accumulation leads to the decrease in breakdown strength in high magnetic field.

Effect of Vertical High Magnetic Field on the Morphology of Solid-Liquid Interface during the Directional Solidification of Zn-2wt.%Bi Immiscible Alloy

The morphology of the solid-liquid (S-L) interface is crucial for the directionally solidified microstructures of various alloys. This paper investigates the effect of vertical high magnetic field (VHMF) on the morphology evolution of the S-L interface and the solidified microstructure during the directional solidification of Zn-2wt.%Bi immiscible alloy. The results indicate that the morphology of the S-L interface is highly dependent on the VHMF, resulting in various solidified microstructures. When the growth rate was 1 μm/s, the aligned droplets were formed directly at the disturbed S-L interface under a 1 T VHMF. However, the stability of the S-L interface was improved to form a stable Bi-rich fiber under a 5 T VHMF. When the growth rate was 5 μm/s, the S-L interface was changed from cellular to dendritic to cellular again with increasing magnetic flux density. A theory regarding constitutional supercooling and efficient solute diffusion has been proposed to explain the S-L interface transition under the VHMF. The difference in the effective diffusion capacity of the solute originates from the thermoelectric magnetic effect and the magneto-hydrodynamic damping effect. The present work may initiate a new method to transform the solidified microstructures of immiscible alloys via an applied magnetic field during directional solidification.

Pressure-induced magnetic transformations in Cd3As2+MnAs hybrid composite

Considerable interest to magnetism of MnAs both in bulk or in the form of epitaxial films is stimulated by its applications as a magnetocaloric material and in spintronic devices. Since the MnAs films deposited on GaAs reproduce well a magnetic transformation related to α–β magnetostructural transition that occurs in bulk MnAs, this first-order phase transition occurs through a phase coexistence over a wide temperature range. Here, we considered the same magnetostructural transition in a bulk hybrid structure based on micrometer-scaled MnAs inclusions embedded into the Cd3As2 matrix. In particular, the effect of high pressure and magnetic fields on the ferromagnetic transition temperature, TC, in a composite Cd3As2 + 30 mol. % MnAs has been studied. We found that at ambient pressure, the transition from α-MnAs to β-MnAs is accompanied by the absence of thermal hysteresis of magnetization, implying a phase coexistence regime. The hysteresis width does not markedly increase even at pressures about P = 0.35 GPa, and displacement of TC occurs with a rate of dTC/dP ∼ −91.42 K/GPa. In the temperature region of the α–β phase coexistence, a local peak at T = 283 K and P = 1 GPa is observed, which is associated with an antiferromagnetic order of MnAs inclusions. Direct measurements of isothermal magnetization vs pressure indicate both the stabilization of the ferromagnetic hexagonal α phase at P &amp;lt; Pmax and the development of an orthorhombic antiferromagnetic long-range order, which propagate up to 5 GPa.

Magnetohydrodynamic blood flow study in stenotic coronary artery using lattice Boltzmann method

Background and objective: Cardiovascular diseases such as atherosclerosis are the first engender of death in the world. The malfunctioning of cardiovascular system is attributed mainly to hemodynamics. However, blood magnetic properties are of major haemodynamic interest, with significant clinical applications. The aim of this work is to study numerically the effect of high magnetic field on blood flow in stenotic artery.Methods: In this paper, a double population D2Q9 lattice Boltzmann model is proposed. Velocity and magnetic field are both solved using Lattice Boltzmann method with single relaxation time. Blood is considered homogeneous and Newtonian bio-magnetic fluid. The results of the proposed model are compared and validated by recent numerical and experimental studies in the literature and show good agreement. In this study, simulations are carried out for both hydrodynamics and magneto-hydrodynamics. For the magneto-hydrodynamic case, five values of Hartmann number of 10, 30, 50, 75 and 100 at Reynolds number of 400, 600 and 800 are investigatedResults: The results show that velocity and recirculation zone increase with the increase of the degree of stenosis and Reynolds number. In addition, a considerable decrease in velocity, recirculation zones and pressure drop across the stenotic artery is noticed with the increase of Hartmann number.Conclusion: The suggested model is found to be effective and accurate in the treatment of magneto-hydrodynamic blood flow in stenotic artery. The found results can be used by clinicians in the treatment of certain cardiovascular disorders and in regulating blood flow movement, especially during surgical procedures.

High Magnetic Field Effects on Cu-precipitation Behavior of Fe-1mass%Cu at 773 K

High Magnetic Field Effects on Cu-precipitation Behavior of Fe-1mass%Cu at 773 K

Mechanism of High Magnetic Field Effect on the D03-L12 Phase Transition in Fe-Ga Alloys

Mechanism of High Magnetic Field Effect on the D03-L12 Phase Transition in Fe-Ga Alloys

Effects of High Magnetic Fields on the Diffusion of Biologically Active Molecules

The diffusion of biologically active molecules is a ubiquitous process, controlling many mechanisms and the characteristic time scales for pivotal processes in living cells. Here, we show how a high static magnetic field (MF) affects the diffusion of paramagnetic and diamagnetic species including oxygen, hemoglobin, and drugs. We derive and solve the equation describing diffusion of such biologically active molecules in the presence of an MF as well as reveal the underlying mechanism of the MF’s effect on diffusion. We found that a high MF accelerates diffusion of diamagnetic species while slowing the diffusion of paramagnetic molecules in cell cytoplasm. When applied to oxygen and hemoglobin diffusion in red blood cells, our results suggest that an MF may significantly alter the gas exchange in an erythrocyte and cause swelling. Our prediction that the diffusion rate and characteristic time can be controlled by an MF opens new avenues for experimental studies foreseeing numerous biomedical applications.