Random magnetic anisotropy approach in amorphous Fe88.4Zr11.6 films: Effects of hydrogen implantation

Alouhmy, M.; Moubah, R.; Yamkane, Z.; Abid, M.; Lassri, H.

doi:10.1016/j.jnoncrysol.2021.120876

Cited by 4 publications

(1 citation statement)

References 28 publications

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“…This method, which constitutes a non-equilibrium synthesis process, makes it possible to obtain metastable nanostructured powders from a mixture of elementary powders. We tailored the mean field theory (MFT) [56,57] and random magnetic anisotropy (RMA) [58,59] to investigate the magnetic moments, exchange interactions, and magnetic anisotropy properties. The correlation between microstructure and magnetic properties is discussed.…”

Section: Introductionmentioning

confidence: 99%

Influence of Chemical Substitution and Light Element Insertion on the Magnetic Properties of Nanocrystalline Pr2Co7 Compound

2022

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It is well recognized that intermetallics based on rare-earth (R) and transition metals (T) display numerous interesting magnetic properties, leading to potential applications in different fields. The latest progress regarding magnetic properties and the magnetocaloric effect (MCE) in the nanostructured Pr2Co7 compound, as well as its carbides and hydrides, is reviewed in this paper. Some of this progress reveals remarkable MCE performance, which makes it attractive in the field of magnetic refrigeration at high temperatures. With the purpose of understanding the magnetic and magnetocaloric characteristics of these compounds, the crystal structure, microstructure, and magnetism are also brought into focus. The Pr2Co7 compound has interesting magnetic properties, such as a high Curie temperature TC and uniaxial magnetocrystalline anisotropy. It crystallizes in a hexagonal structure (2:7 H) of the Ce2Ni7 type and is stable at relatively low temperatures (Ta≤ 1023 K), or it has a rhombohedral structure (2:7 R) of the Gd2Co7 type and is stable at high temperatures (Ta≥ 1223 K). Studies of the magnetocaloric properties of the nanocrystalline Pr2Co7 compound have shown the existence of a large reversible magnetic entropy change (ΔSM) with a second-order magnetic transition. After its substitution, we showed that nanocrystalline Pr2Co7−xFex compounds that were annealed at Ta = 973 K crystallized in the 2:7 H structure similarly to the parent compound. The extended X-ray absorption fine-structure (EXAFS) spectra adjustments showed that Fe atoms preferably occupy the 12k site for x ≤ 1. The study of the magnetic properties of nanocrystalline Pr2Co7−xFex compounds revealed an increase in TC of about 26% for x = 0.5, as well as an improvement in the coercivity, Hc (12 kOe), and the (BH)max (9 MGOe) product. On the other hand, the insertion of C atoms into the Pr2Co7 cell led to a marked improvement in the TC value of 21.6%. The best magnetic properties were found for the Pr2Co7C0.25 compound annealed at 973 K, Hc = 10.3 kOe, and (BH)max = 11.5 MGOe. We studied the microstructure, hydrogenation, and magnetic properties of nanocrystalline Pr2Co7Hx hydrides. The crystal structure of the Pr2Co7 compound transformed from a hexagonal (P63/mmc) into an orthorhombic (Pbcn) and monoclinic (C2/c) structure during hydrogenation. The absorption of H by the Pr2Co7 compound led to an increase in the TC value from 600 K at x = 0 to 691 K at x = 3.75. The Pr2Co7H0.25 hydride had optimal magnetic properties: Hc = 6.1 KOe, (BH)max = 5.8 MGOe, and TC = 607 K. We tailored the mean field theory (MFT) and random magnetic anisotropy (RMA) methods to investigate the magnetic moments, exchange interactions, and magnetic anisotropy properties. The relationship between the microstructure and magnetic properties is discussed. The obtained results provide a fundamental reference for adapting the magnetic properties of the Pr2Co7, Pr2Co6.5Fe0.5, Pr2Co7C0.25, and Pr2Co7H0.25 compounds for potential permanent nanomagnets, high-density magnetic recording, and magnetic refrigeration applications.

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Section: Introductionmentioning

confidence: 99%

Influence of Chemical Substitution and Light Element Insertion on the Magnetic Properties of Nanocrystalline Pr2Co7 Compound

2022

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Exploring Microstructure and Magnetic Domain Evolution in the As-cast Soft Magnetic Fe74B20Nb2Hf2Si2 Alloy: A Comprehensive Study Using STEM, Lorentz TEM, and LM-STEM DPC Microscopy

Czaja,

Rezaei-Shahreza,

Hasani

et al. 2024

Metall Mater Trans A

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This study delves into subtle changes in the microstructure and domain arrangement of a Fe74B20Nb2Hf2Si2 soft magnetic amorphous alloy. Utilizing transmission electron microscopy in Lorentz mode, low-magnification STEM, and differential phase contrast analysis (DPC), the research explores both the as-cast state and annealed samples. The results confirmed the formation of α-Fe, Fe23B6, Fe2(Hf, Nb), and Fe2B crystalline phases with increasing annealing temperature. Consequently, these crystallization stages induce significant alterations in magnetic domain size and spatial distribution due to microstructural changes. As the crystallization temperature rises, the volume fraction of crystalline phases increases, leading to modifications in the arrangement and size of magnetic domains. The decrease in magnetic domain size, associated with the formation of pinning sites during heat treatment, leads to alterations in soft magnetic properties. This includes an increase in coercivity (Hc) up to 40 A/m in the sample annealed at the temperature range of the third crystallization stage compared to the as-cast sample (1.5 A/m). Furthermore, as the annealing temperature rises, there is a corresponding increase in saturation magnetization (Ms), which reached to 1.71 T in the sample annealed within the temperature range of the third crystallization stage. These findings hold substantial implications for the practical applications of the Fe-based soft bulk metallic glasses (BMGs) alloy across various industries.

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Investigation of the unusual temperature dependence of magnetic anisotropy in nanocrystalline Fe96Zr4 films

Alouhmy

Moubah

Lassri

et al. 2022

Journal of Magnetism and Magnetic Materials

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Random magnetic anisotropy approach in amorphous Fe88.4Zr11.6 films: Effects of hydrogen implantation

Cited by 4 publications

References 28 publications

Influence of Chemical Substitution and Light Element Insertion on the Magnetic Properties of Nanocrystalline Pr2Co7 Compound

Influence of Chemical Substitution and Light Element Insertion on the Magnetic Properties of Nanocrystalline Pr2Co7 Compound

Exploring Microstructure and Magnetic Domain Evolution in the As-cast Soft Magnetic Fe74B20Nb2Hf2Si2 Alloy: A Comprehensive Study Using STEM, Lorentz TEM, and LM-STEM DPC Microscopy

Investigation of the unusual temperature dependence of magnetic anisotropy in nanocrystalline Fe96Zr4 films

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