Novel RE-free Nanocomposite Magnets

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanocomposite Materials".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 5349

Special Issue Editors

National Institute for Materials Physics, 077125 Magurele, Romania
Interests: RE-free nanocomposite magnets; L10 magnets; structural phase stability

Special Issue Information

Dear Colleagues,

The present Special Issue invites the submission of research papers on theoretical as well as experimental approaches toward conceiving and developing RE-free nanocomposite magnets. The motivation for editing this Special Issue is linked to the current needs for alternative solutions to the commonly employed magnetic materials.

Magnets and especially permanent magnets are widely used in most industrial technologies today—from domestic household to magnetic recording media, from the automotive to the aircraft industry, for renewable energy generation for wind turbine components. Industry demand for magnets is continuously growing with the increased emergence of autonomous and hybrid electric vehicles and wind turbines, new developments in the automation and robotics industry, new smartphones and telecom, as well as the potential use in a wide range of medical devices, for imaging, diagnostics, and therapy. This is why the research community has embarked on a quest for magnetic materials based on abundant elements which are less costly and easy to process, without trading off too much of the magnetic performances of rare earth magnets.

The present Special Issue will address all the challenges encountered in developing novel RE-free nanocomposite magnets, including but not limited to:

  • Theory and modeling of novel magnetic alloys compositions;
  • Synthesis challenges and microstructure optimization for novel nanocomposite magnets;
  • Magnetic phase coexistence and phase stability with temperature;
  • Hard–soft exchange coupling in multiphase magnetic nanocomposites;
  • Optimization of magnetic performances in RE-free nanocomposite magnets;
  • Trade-off between lowering costs and holding high enough magnetic performances;
  • Magnetic performances in extreme conditions of operation.

Dr. Alina Daniela Crişan
Dr. Ovidiu Crisan
Guest Editors

Manuscript Submission Information

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Keywords

  • RE-free nanocomposite magnets
  • hard-soft exchange coupling
  • magnetic stability
  • structural phase transformation

Published Papers (5 papers)

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Research

13 pages, 2661 KiB  
Article
Novel Rare Earth (RE)-Free Nanocomposite Magnets Derived from L10-Phase Systems
by Alina Daniela Crisan and Ovidiu Crisan
Nanomaterials 2023, 13(5), 912; https://doi.org/10.3390/nano13050912 - 01 Mar 2023
Viewed by 1256
Abstract
In the quest for novel rare earth (RE)-free magnetic materials, which also exhibit other additional properties such as good corrosion resistance and potential to operate at higher temperatures, an alloy deriving from the binary FePt system, with Mo and B addition, has been [...] Read more.
In the quest for novel rare earth (RE)-free magnetic materials, which also exhibit other additional properties such as good corrosion resistance and potential to operate at higher temperatures, an alloy deriving from the binary FePt system, with Mo and B addition, has been synthesized for the first time, using the out-of-equilibrium method of rapid solidification form the melt. The alloy with the composition Fe49Pt26Mo2B23 has been subjected to thermal analysis through differential scanning calorimetry in order to detect the structural disorder – order phase transformation as well as to study the crystallization processes. For the stabilization of the formed hard magnetic phase, the sample has been annealed at 600 °C and further structurally and magnetically characterized by means of X-ray diffraction, transmission electron microscopy, 57Fe Mössbauer spectrometry as well as magnetometry experiments. It has been proven that after annealing at 600 °C the tetragonal hard magnetic L10 phase emerges via crystallization from a disordered cubic precursor and becomes the predominant phase in terms of relative abundance. Moreover, it has been revealed by quantitative analysis via Mössbauer spectroscopy that the annealed sample exhibits a complex phase structure, where the L10 hard magnetic phase is accompanied by few other soft magnetic phases, in minority abundance: the cubic A1, orthorhombic Fe2B and residual intergranular region. The magnetic parameters have been derived from 300 K hysteresis loops. It was shown that, contrary to the as-cast sample which behaves as a typical soft magnet, the annealed sample presents strong coercivity and high remanent magnetization, accompanied by a large saturation magnetization. These findings offers good insight into the potential developing of novel class of RE-free permanent magnets, based on Fe-Pt-Mo-B, where the magnetic performance emerges from the co-existence of hard and soft magnetic phases in controlled and tunable proportions, capable of finding good applicability in fields requiring good catalytic properties and strong corrosion resistance. Full article
(This article belongs to the Special Issue Novel RE-free Nanocomposite Magnets)
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14 pages, 2224 KiB  
Article
Microcrystallization Effects Induced by Laser Annealing in Cr-Al-C Ion-Beam-Sputtered Films
by Ovidiu Crisan and Alina Daniela Crisan
Nanomaterials 2022, 12(23), 4136; https://doi.org/10.3390/nano12234136 - 23 Nov 2022
Cited by 1 | Viewed by 1203
Abstract
The microcrystallization effects induced by the real-time laser annealing in Cr-Al-C ion-sputtered films with an off-stoichiometric composition are studied. The laser annealing has been performed during Raman experiments with tunable laser power densities. Morphostructural changes induced during laser annealing were investigated by scanning [...] Read more.
The microcrystallization effects induced by the real-time laser annealing in Cr-Al-C ion-sputtered films with an off-stoichiometric composition are studied. The laser annealing has been performed during Raman experiments with tunable laser power densities. Morphostructural changes induced during laser annealing were investigated by scanning electron microscopy. It has been proven that real-time laser annealing in the high-laser-power-density mode promotes quite clearly the formation of nanograins through surface microcrystallization. Detailed Raman analysis allowed for the observation of the optical modes that unequivocally identifies the low-symmetry 211 MAX phase in both low- and high-power-density modes. Such findings confirming the microcrystallization as well as the stabilization of the grain boundaries by carbon nanoclustering are confirmed by X-ray diffraction results, where the single-phase hexagonal 211 was unequivocally proven to form in the high-laser-power-density mode. The microcrystallization via laser annealing was also found to be beneficial for the elastic behavior, as the hardness values between 16 and 26 GPa were found after laser annealing, accompanied by a significantly high Young’s bulk modulus. Such large values, larger than those in bulk compounds, are explicable by the nanometric grain sizes accompanied by the increase of the grain boundary regions. Full article
(This article belongs to the Special Issue Novel RE-free Nanocomposite Magnets)
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18 pages, 3676 KiB  
Article
Temperature-Dependent Phase Evolution in FePt-Based Nanocomposite Multiple-Phased Magnetic Alloys
by Ovidiu Crisan, Alina Daniela Crisan and Nirina Randrianantoandro
Nanomaterials 2022, 12(23), 4122; https://doi.org/10.3390/nano12234122 - 22 Nov 2022
Viewed by 738
Abstract
A quaternary Fe–Pt–Nb–B alloy has been fabricated by the melt spinning method with the purpose of the formation of crystallographically coherent multiple magnetic phases, emerging from the same metastable precursor, as well as to investigate the phase interactions and the influence of their [...] Read more.
A quaternary Fe–Pt–Nb–B alloy has been fabricated by the melt spinning method with the purpose of the formation of crystallographically coherent multiple magnetic phases, emerging from the same metastable precursor, as well as to investigate the phase interactions and the influence of their coupling on magnetic performances. For this purpose, extended structural and magnetic investigations were undertaken by making use of X-ray diffraction, transmission electron microscopy, and 57Fe Mössbauer spectroscopy, as well as magnetic measurements using SQUID magnetometry. It was documented that intermediate metastable phases formed during primary crystallization, in intermediate stages of annealing, and a growth-dominated mode was encountered for the secondary crystallization stage upon annealing at 700 °C and 800 °C where fcc Fe3Pt and fct Fe2B polycrystalline were formed. The Mössbauer investigations have documented rigorously the hyperfine parameters of each of the observed phases. The fcc A1 FePt phase was shown to exhibit a peculiar ferromagnetic transition, and this transition has been proven to occur gradually between 300 K and 77 K. The magnetic measurements allowed us to identify the annealing at 700 °C as optimal for obtaining good magnetic features. Coercive field dependence shows similarities to the random anisotropy model for samples annealed at 500 °C to 700 °C which are nanocrystalline. These results show good perspectives for use in applications where different magnetic states are required at different operating temperatures. Full article
(This article belongs to the Special Issue Novel RE-free Nanocomposite Magnets)
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22 pages, 3145 KiB  
Article
Reverse Magnetization Behavior Investigation of Mn-Al-C-(α-Fe) Nanocomposite Alloys with Different α-Fe Content Using First-Order Reversal Curves Analysis
by Seyed Nourallah Attyabi, Seyyed Ali Seyyed Ebrahimi, Zahra Lalegani and Bejan Hamawandi
Nanomaterials 2022, 12(19), 3303; https://doi.org/10.3390/nano12193303 - 22 Sep 2022
Cited by 2 | Viewed by 1445
Abstract
The reverse magnetization behavior for bulk composite alloys containing Mn-Al-C and α-Fe nanoparticles (NPs) has been investigated by hysteresis loops, recoil, and first-order reversal curves (FORC) analysis. The effect of adding different percentages of α-Fe (5, 10, 15, and 20 wt. %) on [...] Read more.
The reverse magnetization behavior for bulk composite alloys containing Mn-Al-C and α-Fe nanoparticles (NPs) has been investigated by hysteresis loops, recoil, and first-order reversal curves (FORC) analysis. The effect of adding different percentages of α-Fe (5, 10, 15, and 20 wt. %) on the magnetic properties and demagnetization behavior of Mn-Al-C nanostructured bulk magnets was investigated. The fabricated nanocomposites were characterized by XRD and VSM for structural analysis and magnetic behavior investigations, respectively. The demagnetization curve of the sample Mn-Al-C-5wt. % α-Fe showed a single hard magnetic behavior and showed the highest increase in remanence magnetization compared to the sample without α-Fe, and therefore this combination was selected as the optimal composition for FORC analysis. Magnetic properties for Mn-Al-C-5 wt. % α-Fe nanocomposite were obtained as Ms = 75 emu/g, Mr = 46 emu/g, Hc = 3.3 kOe, and (BH)max = 1.6 MGOe, indicating a much higher (BH)max than the sample with no α-Fe. FORC analysis was performed to identify exchange coupling for the Mn-Al-C-0.05α-Fe nanocomposite sample. The results of this analysis showed the presence of two soft and hard ferromagnetic components. Further, it showed that the reverse magnetization process in the composite sample containing 5 wt. % α-Fe is the domain rotation model. Full article
(This article belongs to the Special Issue Novel RE-free Nanocomposite Magnets)
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17 pages, 1651 KiB  
Article
Change in Magnetic Anisotropy at the Surface and in the Bulk of FINEMET Induced by Swift Heavy Ion Irradiation
by Ernő Kuzmann, Sándor Stichleutner, Libor Machala, Jiří Pechoušek, René Vondrášek, David Smrčka, Lukáš Kouřil, Zoltán Homonnay, Michael I. Oshtrakh, András Mozzolai, Vladimir A. Skuratov, Mátyás Kudor, Bence Herczeg and Lajos Károly Varga
Nanomaterials 2022, 12(12), 1962; https://doi.org/10.3390/nano12121962 - 08 Jun 2022
Cited by 3 | Viewed by 1515
Abstract
57Fe transmission and conversion electron Mössbauer spectroscopy as well as XRD were used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET samples with a composition of Fe73.5Si13.5Nb3B9Cu1. The [...] Read more.
57Fe transmission and conversion electron Mössbauer spectroscopy as well as XRD were used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET samples with a composition of Fe73.5Si13.5Nb3B9Cu1. The XRD of the samples indicated changes neither in the crystal structure nor in the texture of irradiated ribbons as compared to those of non-irradiated ones. However, changes in the magnetic anisotropy both in the bulk as well as at the surface of the FINEMET alloy ribbons irradiated by 160 MeV 132Xe ions with a fluence of 1013 ion cm−2 were revealed via the decrease in relative areas of the second and fifth lines of the magnetic sextets in the corresponding Mössbauer spectra. The irradiation-induced change in the magnetic anisotropy in the bulk was found to be similar or somewhat higher than that at the surface. The results are discussed in terms of the defects produced by irradiation and corresponding changes in the orientation of spins depending on the direction of the stress generated around these defects. Full article
(This article belongs to the Special Issue Novel RE-free Nanocomposite Magnets)
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