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照宣, 宮崎; 亮, 高橋; 慶蔵, 久武; 実, 高橋

doi:10.3379/jmsjmag.7.55

Cited by 3 publications

(5 citation statements)

References 12 publications

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“…The magnetoelastic energy is connected with the saturated magnetostriction constant λ S . This quantity can be simply measured and, as found experimentally, Co-B alloys have negative λ S as opposed to the positive λ S of Fe-B alloys [22]. This indicates a significant influence of the alloy's chemical composition on magnetoelastic interactions in the sample.…”

Section: Basic Assumptionsmentioning

confidence: 62%

“…This indicates a significant influence of the alloy's chemical composition on magnetoelastic interactions in the sample. The anisotropy energy also depends on the amorphous alloy chemistry, as has been shown in [22,23].…”

Section: Basic Assumptionsmentioning

confidence: 71%

“…The peak just below the Curie temperature is usually narrow, and originates from a ferromagnetic to paramagnetic phase transition. This description of a typical MAE spectrum holds for a wide variety of compositions, from binary (Co, Fe)-M, where M is a metalloid [2][3][4][5] through ternary and quaternary alloys [1,[6][7][8] to multicomponent systems [9]; hence some authors argue (see [10] and references therein) that the magnetic relaxation has a structural, rather than compositional nature.…”

Section: Introductionmentioning

confidence: 99%

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Directional ordering in amorphous Co–Si–B alloys

Andrejco¹,

Vojtaník²

2004

J. Phys.: Condens. Matter

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Directional ordering in the amorphous Co75Si15B10 alloys by means of the magnetic after-effect (MAE) of the initial reluctivity and its influence on the Perminvar effect have been investigated. Two peak MAE spectra were obtained from isochronal measurements for as-cast as well as annealed samples. The spectrum of the as-cast sample has peak maxima at 383 and 545 K. Comparing this MAE spectrum with the spectrum of amorphous Co75B25 alloy, we identified the first peak as a result of Co–B atom pair reorientation (B-type relaxation) and the second one at higher temperatures as a result of Co–Si atom pair reorientation (Si-type relaxation). After annealing, the peaks shift to 442 and 576 K, respectively. For the numerical analysis of Co75Si15B10 MAE spectra we modified the micromagnetic model assuming the existence of more relaxation processes, where each process is connected to the relaxation of one metalloid element. The pre-exponential factor for B-type relaxation was found to be τ0,AC(B) = 7 × 10−17 s with the most probable activation energy QAC*(B) = 1.31 eV. These values correlate very well with the magnetic relaxation (MR) activation parameters of Co75B25 alloy, τ0,AC = 2 × 10−17 s and QAC* = 1.35 eV. Si-type relaxation has activation parameters τ0,AC(Si) = 6 × 10−18 s and QAC*(Si) = 1.96 eV. After annealing the sample at 683 K for 30 min they change to values τ0,AN(B) = 2 × 10−15 s, QAN*(B) = 1.38 eV and τ0,AN(Si) = 3 × 10−17 s, QAN*(Si) = 2.01 eV. The complicated shapes of the long-time isotherms reflect the superposition of two relaxation processes. We have numerically split each isotherm into two sub-isotherms representing the particular contributions of the two relaxation processes. The MAE spectrum of the critical field measured on the as-cast sample also has two peaks, like the reluctivity spectrum. The impact of Co–B and Co–Si atom pairs on the behaviour of the domain wall stabilization potential is discussed for the explanation of the observed MR results.

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Section: Basic Assumptionsmentioning

confidence: 62%

Section: Basic Assumptionsmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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Directional ordering in amorphous Co–Si–B alloys

Andrejco¹,

Vojtaník²

2004

J. Phys.: Condens. Matter

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“…In addition, Fe is a ferromagnetic metal with a very large magnetization at room temperature (1.76 MA/m [3]). However, the SmFe 5 compound is thermodynamically unstable and does not appear in the equilibrium Sm-Fe phase diagram, although the alloy compound Sm(Co 1-x Fe x ) 5 with the CaCu 5 -type structure has been synthesized by the melt-spinning method for x = 0.0 -0.3 [7].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of SmCo5 compound doped with Fe and Ni: An ab initio study

Landa

Söderlind

Parker

et al. 2018

Journal of Alloys and Compounds

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SmCo 5 permanent magnets exhibit enormous uniaxial magnetocrystalline anisotropy energy and have a high Curie temperature. However, a low energy product presents a significant drawback in the performance of SmCo 5 permanent magnets. In order to increase the energy product in SmCo 5 , we propose substituting fixed amount of cobalt with iron in a new magnet, SmFe 3 CoNi, where inclusion of nickel metal makes this magnet thermodynamically stable. We further discuss some basic theoretical magnetic properties of the SmCo 5 compound. IntroductionThree basic material parameters determine the intrinsic properties of hard magnetic materials: (i) spontaneous (saturation) magnetization, M s , (ii) Curie temperature, T c , and (iii) magnetocrystalline anisotropy energy (MAE), K 1 [1]. These three parameters all need to be large for the permanent magnet to be technologically suitable: T c ~ ≥ 550 K, M s ~ ≥ 1 MA/m, K 1 ~ ≥ 4 MJ/m 3 . The desired values of these properties can be achieved by combining transition-metal (TM) with rare-earth-metal (RE) atoms in various intermetallic compounds, where the RE atoms induce a large magnetic anisotropy while the TM atoms provide a large magnetization and high Curie temperature [1,2].SmCo 5 (in the hexagonal CaCu 5 -type structure) magnets exhibit enormous uniaxial MAE of K 1 ~ 17.2 MJ/m 3 , substantially higher than that of Nd 2 Fe 14 B (Neomax) magnets (K 1 ~ 4.9 MJ/m 3 ), and have almost twice the Curie temperature (T c ~ 1020 K) compared to Neomax (T c ~ 588 K) [3,4]. However, Nd 2 Fe 14 B currently dominates the world market for permanent magnets (~ 62 %) [5,6], since it possesses the highest energy performance measured by a record energy product (BH) max of 512 kJ/m 3 , more than twice as high as the energy product of SmCo 5 magnets, (BH) max of 231 kJ/m 3 [3,4]. Although SmCo 5 magnets are more suitable for high temperature applications than Neomax, due to their relatively low energy performance SmCo 5 magnets occupy only ~ 3% of the world market [5,6].From a cost stand point, it would be beneficial to substitute Co atoms with Fe, because Fe in the Earth's crust is ~ 2000 times more abundant than Co and consequently much cheaper. In addition, Fe is a ferromagnetic metal with a very large magnetization at room temperature (1.76 MA/m [3]). However, the SmFe 5 compound is thermodynamically unstable and does not appear in the equilibrium Sm-Fe phase diagram, although the alloy compound Sm(Co 1-x Fe x ) 5 with the CaCu 5 -type structure has been synthesized by the melt-spinning method for x = 0.0 -0.3 [7]. Furthermore, the Curie temperature for Sm(Co 1-x Fe x ) 5 alloys was found to increase from ~ 1020 K to ~ 1080 K when increasing x from 0.0 to 0.2 [8], in contrast to Sm 2 (Co 1-x Fe x ) 17 alloys which exhibit a monotonic decrease in Curie temperature with increasing Fe content [9].The fundamental purpose of the present study is to explore the effect of adding Ni to the SmCo 5 magnet in order to stabilize Sm(Co 1-x Fe x ) 5 alloys containing a sufficient amount of iron to boost the...

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“…With the addition of a small amount of Fe to Co-based amorphous alloys, the magnetostriction value tends towards zero. Hence, a series of CoFe-based amorphous alloys were developed with the aim of attaining zero magnetostrictive material and, hence, high permeability [3][4][5][6][7][8]. such as flux-gate magnetometers and proximity sensors, which require materials with high permeability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fe addition on the crystallization behaviour and Curie temperature of CoCrSiB-based amorphous alloys

Panda

Kumari

Chattoraj

et al. 2005

Philosophical Magazine

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The crystallization behaviour and Curie temperature of melt-spun Co 71Àx Fe x Cr 7 Si 8 B 14 (x ¼ 0, 2, 3.2, 4, 6, 8 and 12 at.%) amorphous alloys have been studied. Differential scanning calorimetry (DSC) showed two stages of crystallization. The first stage of crystallization (T X1 ) in the alloy with 6 at.% Fe was the highest and it had the highest activation energy. X-ray diffraction studies revealed that the primary crystalline phase is hcp-(CoCr) 2 Si for Fe-free alloy, whereas (CoFeCr) 2 Si and (CoFeCr) 3 Si phases were formed with the addition of Fe. hcp-Co was also formed along with these phases. The secondary crystalline phases were fcc-Co and various boron-rich phases. The Curie temperature of the alloys also changed with the addition of Fe to the system. Like the primary crystallization temperature, the Curie temperature of the alloys did not vary systematically with the Fe content. The addition of Fe to the Co-based system changes the nearest-neighbour interaction. This changes the exchange interaction between the transition metal elements. Due to the asymmetry in the Bethe-Slater curve, a systematic variation with Fe addition was not observed in the Curie temperature measurement.

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Untitled

Cited by 3 publications

References 12 publications

Directional ordering in amorphous Co–Si–B alloys

Directional ordering in amorphous Co–Si–B alloys

Thermodynamics of SmCo5 compound doped with Fe and Ni: An ab initio study

Effect of Fe addition on the crystallization behaviour and Curie temperature of CoCrSiB-based amorphous alloys

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