Anisotropic characteristics and improved magnetic performance of Ca–La–Co-substituted strontium hexaferrite nanomagnets

Abstract Recent studies on next-generation permanent magnets have focused on filling in the gap between rare-earth magnets and rare-earth-free magnets, taking into account both the cost-effectiveness and magnetic performance of the magnetic materials. As an improved rare-earth-free magnet candidate, here, Ca-substituted M-type Sr-lean hexaferrite particles within a nano- to micro-scale regime, produced using an ultrasonic spray pyrolysis method, are investigated. Theoretically, the maximum coercivity (Hc) can be achieved in submicron Sr-ferrite crystals (i.e., 0.89 μm). The plate-like resultants showed a significant enhancement in Hc, up to a record high of 7880.4 Oe, with no deterioration in magnetization (M: 71–72 emu/g). This resulted in more favorable magnetic properties than those of the traditional Sr–La–Co ferrites. On the basis of microstructural analysis and fitting results based on the law of approach to saturation method, the Ca-substitution effects on the change in size and anisotropic characteristics of the ferrite particles, including pronounced lateral crystal growth and a strong increase in magnetocrystalline anisotropy, are clearly demonstrated. The cost-effective, submicron, and Ca-substituted Sr-ferrite is an excellent potential magnet and moreover may overcome the limitations of traditional hard magnetic materials.

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Special Issue: Advances in Computational Electromagnetics

Magnetochemistry ◽

10.3390/magnetochemistry7060089 ◽

2021 ◽

Vol 7 (6) ◽

pp. 89

Author(s):

Valerio De Santis

Keyword(s):

Rare Earth ◽

Magnetic Materials ◽

Permanent Magnets ◽

Computational Electromagnetics ◽

Superconducting Materials ◽

Special Issue ◽

Full Characterization ◽

Recent Advances

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...]

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Contribution of Additive Manufacturing of Rare Earth Material to the Increase in Performance and Resource Efficiency of Permanent Magnets

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.882.135 ◽

2018 ◽

Vol 882 ◽

pp. 135-141

Author(s):

Nikolaus Urban ◽

Alexander Meyer ◽

Vitalij Keller ◽

Jörg Franke

Keyword(s):

Rare Earth ◽

Additive Manufacturing ◽

Permanent Magnets ◽

High Energy ◽

Significant Loss ◽

Material Behavior ◽

Parameter Study ◽

Great Effort ◽

Magnetic Performance ◽

Process Route

Powerful permanent magnets are of essential meaning for electric drives as well as for environmental friendly energy conversion in general. The main requirements for these applications are high energy products, coercivity and remanent polarization, thermal stability as well as affordable price. As state of the art, rare earth permanent magnets, frequently consisting of NdFeB based alloys, meet these requirements. When complex geometric shapes like arcs, shells or freeform surfaces are required by the application, a trade-off has to be taken into account between magnetic performance and post magnet-fabrication processing steps. Either bonded magnets can be produced with great variety of geometries while accepting low magnetic performance due to a significant amount of nonmagnetic plastic binder matrix, or sintered blocks with great magnetic performance have to be machined out to the specified shape accepting great effort for grinding or wire cutting as well as a significant loss of valuable material. To overcome the drawback of both conventional established magnet manufacturing processes, Laser Beam Melting (LBM) is investigated to provide an alternative process route for magnet production. This innovative Additive Manufacturing (AM) process offers tool less production of nearly any thinkable geometry by use of a metal powder bed fusing process. Due to the challenging material behavior, a detailed parameter study is presented including a systematic design of experiment (DoE) approach. The connection between process parameters, density and key performance indicators on the B/H-curve is broken down.

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Solid-state magnetic materials for magnetic levitation transport

Journal of Radio Electronics ◽

10.30898/1684-1719.2021.8.20 ◽

2021 ◽

Vol 2021 (8) ◽

Author(s):

D.A. Karpukhin ◽

◽

A.O. Petrov ◽

V.V. Koledov ◽

D.A. Suslov ◽

...

Keyword(s):

Rare Earth ◽

High Temperature ◽

Solid State ◽

Magnetic Materials ◽

Permanent Magnets ◽

Magnetic Levitation ◽

High Temperature Superconductivity ◽

Translational Motion ◽

Practical Interest ◽

Rare Earth Compound

Study and implementation of innovative systems of environmentally friendly and energy-efficient transport based on magnetic levitation, the principle of operation of which is based on the use of new solid-state magnetic materials based on compounds of rare earth materials, in particular materials with high-temperature superconductivity based on Y, permanent magnets based on Nd and Sm and magnetocaloric alloys based on Dy, Tb are of great interest throughout the world. In this work, the basic principles of magneto-levitation transport with the most economical principle of acceleration and deceleration - gravitational - are studied experimentally on mock-ups. The strength characteristics were measured: the levitation force and the lateral stabilization force, as well as losses during periodic translational motion of a cryostat with high-temperature superconducting elements made of ceramic material Y-Ba-Cu-O over the paths of permanent magnets made of the rare-earth compound Nd-Fe-B. A system for measuring the speed and compensation of losses for the implementation of continuous motion has been created and tested. The presented results indicate the possibility of scaling the layout project. It is concluded that the investigated scheme may be of practical interest for intracity and local transport communication with high comfort, environmental friendliness and record economy in the case of a successful solution of the problem of cooling HTSC elements to the temperature of the phase transition to the superconducting state, for example, using new principles of solid-state magnetic cooling based on compounds Dy-N, Tb-Ni, etc.

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L10 rare-earth-free permanent magnets: The effects of twinning versus dislocations in Mn-Al magnets

Physical Review Materials ◽

10.1103/physrevmaterials.4.094402 ◽

2020 ◽

Vol 4 (9) ◽

Author(s):

Yuxiao Jia ◽

Yuye Wu ◽

Shuang Zhao ◽

Shulan Zuo ◽

Konstantin P. Skokov ◽

...

Keyword(s):

Rare Earth ◽

Permanent Magnets

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Temperature-dependent magnetocrystalline anisotropy of rare earth/transition metal permanent magnets from first principles: The light RCo5 (R=Y, La-Gd) intermetallics

Physical Review Materials ◽

10.1103/physrevmaterials.3.101401 ◽

2019 ◽

Vol 3 (10) ◽

Cited By ~ 11

Author(s):

Christopher E. Patrick ◽

Julie B. Staunton

Keyword(s):

Rare Earth ◽

Transition Metal ◽

First Principles ◽

Permanent Magnets ◽

Magnetocrystalline Anisotropy ◽

Temperature Dependent

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Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

Applied Sciences ◽

10.3390/app11073102 ◽

2021 ◽

Vol 11 (7) ◽

pp. 3102

Author(s):

Md. Zakirul Islam ◽

Seungdeog Choi ◽

Malik E. Elbuluk ◽

Sai Sudheer Reddy Bonthu ◽

Akm Arafat ◽

...

Keyword(s):

Rare Earth ◽

Permanent Magnets ◽

Design Procedure ◽

Lumped Parameter Model ◽

High Power Density ◽

Analytical Design ◽

Synchronous Reluctance Motor ◽

Lumped Parameter ◽

Reluctance Motor ◽

External Rotor

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

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Effect of the Temperature on the Magnetic and Energetic Properties of Soft Magnetic Composite Materials

Energies ◽

10.3390/en14154400 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4400

Author(s):

Luca Ferraris ◽

Fausto Franchini ◽

Emir Pošković ◽

Marco Actis Grande ◽

Róbert Bidulský

Keyword(s):

Magnetic Materials ◽

Eddy Currents ◽

Electrical Machines ◽

Soft Magnetic Materials ◽

Magnetic Composite ◽

Soft Magnetic ◽

Soft Magnetic Composite ◽

Magnetic Performance ◽

Magnetic Circuits ◽

Energetic Characterization

In recent years, innovative magnetic materials have been introduced in the field of electrical machines. In the ambit of soft magnetic materials, laminated steels guarantee good robustness and high magnetic performance but, in some high-frequency applications, can be replaced by Soft Magnetic Composite (SMC) materials. SMC materials allow us to reduce the eddy currents and to design innovative 3D magnetic circuits. In general, SMCs are characterized at room temperature, but as electrical machines operate at high temperature (around 100 °C), an investigation analysis of the temperature effect has been carried out on these materials; in particular, three SMC samples with different binder percentages and process parameters have been considered for magnetic and energetic characterization.

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