Magnetic field-induced nitridation of Sm2Fe17

Onoue, Masahira; Kobayashi, Ryota; Mitsui, Yoshifuru; Umetsu, Rie Y.; Uwatoko, Yoshiya; Koyama, K.

doi:10.1016/j.jallcom.2020.155193

Cited by 10 publications

(2 citation statements)

References 28 publications

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“…For condition of T n = 743 K, almost FN Sm 2 Fe 17 N 2.9 was obtained using IFN-5T, while x was only 2.3 using ZFN. Magnetic field promotes nitrogenation for the temperature T range of 623743 K. From XRD analysis for ZFN and IFN-5T samples, 17) we confirmed that the poornitride (PN) and FN phase coexisted in the nitride sample with x ¯1.9. However, the XRD patterns for x = 2.3 and 2.9 did not show clearly the two phase coexistence of the PN and FN phases but a single nitride phase with a very small amount of ¡-Fe phase.…”

Section: Resultsmentioning

confidence: 52%

Magnetic Field Effect on Nitrogenation of Sm2Fe17

et al. 2020

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Nitrogenation of Sm 2 Fe 17 powder was performed under a zero field and a magnetic field of 5 T at 623, 673 and 743 K to clarify the magnetic field effect on nitrogenation. Applying a magnetic field of 5 T induced nitrogenation compared with zero-field nitrogenation, and almost fully nitride Sm 2 Fe 17 N 2.9 was obtained at 743 K. Mössbauer spectroscopy results suggested that a 5-T magnetic field promoted the phase transformation to the fully-nitride Sm 2 Fe 17 N 3 phase. The magnetic field effect was discussed based on the magnetic energy gain and magnetic properties of host Sm 2 Fe 17 and fully nitride Sm 2 Fe 17 N 3 .

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Section: Resultsmentioning

confidence: 52%

Magnetic Field Effect on Nitrogenation of Sm2Fe17

et al. 2020

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“…In recent years, magnetic nanomaterials based on rare-earth elements (R) and transition metals (T) have been widely investigated due to their extremely diverse potential applications in industrial fields [1][2][3][4][5][6][7][8]. These properties are often used to produce soft, hard, or semi-hard magnetic materials [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The origin of these exceptional magnetic properties is particularly due to the coexistence of of two complementary kinds of magnetism: the localized magnetism characteristic of rare-earth (R) electrons and the itinerant magnetism of the 3d electrons of transition metals (T), such as cobalt (Co) and iron (Fe) [24][25][26][27][28][29][30][31][32][33].…”

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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