Nanocrystalline Hf and Ta containing FeCo based alloys for high frequency applications

Lucas, M. S.; Bourne, W.C.; Sheets, A. O.; Brunke, Lyle; Alexander, M.; Shank, Joshua; Michel, Eric; Semiatin, S. L.; Horwath, J.; Turgut, Z.

doi:10.1016/j.mseb.2011.05.044

Cited by 28 publications

(10 citation statements)

References 21 publications

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“…A residual magnetization of ∼20 emu cm −3 can be observed in the temperature range from 600 to 705 K. This originates from structural relaxation and nucleation of crystals before apparent crystal growth occurring in the a-CFTBO thin film. At about 705 K the magnetization starts to increase due to such crystallization, consistent with early findings that nanocrystallized CoFeMB (M=Ta, Hf) thin film has a higher Curie temperature than the corresponding amorphous CoFeMB smaple2122. The ferromagnetism together with its semiconducting properties indicates that the single-phase a-CFTBO thin film is a MS.…”

Section: Resultssupporting

confidence: 86%

A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

et al. 2016

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Emerging for future spintronic/electronic applications, magnetic semiconductors have stimulated intense interest due to their promises for new functionalities and device concepts. So far, the so-called diluted magnetic semiconductors attract many attentions, yet it remains challenging to increase their Curie temperatures above room temperature, particularly those based on III–V semiconductors. In contrast to the concept of doping magnetic elements into conventional semiconductors to make diluted magnetic semiconductors, here we propose to oxidize originally ferromagnetic metals/alloys to form new species of magnetic semiconductors. We introduce oxygen into a ferromagnetic metallic glass to form a Co28.6Fe12.4Ta4.3B8.7O46 magnetic semiconductor with a Curie temperature above 600 K. The demonstration of p–n heterojunctions and electric field control of the room-temperature ferromagnetism in this material reflects its p-type semiconducting character, with a mobility of 0.1 cm2 V−1 s−1. Our findings may pave a new way to realize high Curie temperature magnetic semiconductors with unusual multifunctionalities.

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Section: Resultssupporting

confidence: 86%

A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

et al. 2016

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“…Melt-spun and planar flow cast nanocrystalline soft magnetic ribbons are typically thin (20-30 lm) and resistivity can be improved by careful alloy design. 4,5 Additionally, the dimensions of the ribbon lend itself to processing techniques such as magnetic field annealing and strain annealing that can induce large magnetic anisotropies to tune the permeability and reduce anomalous losses caused by domain wall motion. [6][7][8] Further reduction in losses can be achieved, if the ribbon thickness is reduced.…”

mentioning

confidence: 99%

“…4 The frequency range of measurement was too low to see f ec of the rolled annealed sample, but it can be estimated by assuming the thickness reduction of $40% from the unrolled to the rolled sample and the ratio between the l 0 of the unrolled sample and the rolled sample at 5 kHz is $2. Using the unrolled annealed f ec of 100 kHz, the f ec of the rolled sample is estimated to be $1250 kHz.…”

mentioning

confidence: 99%

Reduced losses in rolled Fe73.5Si15.5Nb3B7Cu1 nanocrystalline ribbon

Kernion

Lucas

Horwath

et al. 2013

Journal of Applied Physics

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Eddy currents in magnetic components undergoing high frequency switching can be mitigated by reducing the thickness of the component. Planar flow cast Fe73.5Si15.5Nb3B7Cu1 ribbon was plastically deformed by cold rolling, resulting in a thickness reduction of 38%. Shear band formation was seen and the coercivity was dramatically higher in the rolled ribbon. After crystallization, the hysteresis loop of the rolled ribbon was nearly identical to a non-rolled ribbon and losses were lower in the rolled ribbon above 25 kHz. Reductions in thickness by this method can lead to increases in operating frequency for power conversion applications.

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“…Similar to Nb, both Ta and Hf are normally used in soft magnetic nanocomposites as growth inhibitors. Work on Ta-and Hf-containing nanocrystalline FeCo has been reported by Lucas et al 11 It was observed that these alloys exhibit high resistivity, which results in lower power loss. This finding is particularly promising from the standpoint of high frequency switching applications.…”

Section: Introductionmentioning

confidence: 98%

“…[1][2][3][4][5][6][7] In the synthesis of these alloys, early transition metals (e.g., Nb, Ta, and Hf) and glass formers (e.g., B, Si, and Al) are used to improve glass formability and prevent overgrowth of the grains. [8][9][10][11][12] However, precursors such as B, Nb, Ta, and Hf are expensive and make up for more than 70% of the total alloy cost despite their low concentrations. [13][14][15] Attempts to reduce the alloy cost include the development of B-free alloys and substitution of B with B 4 C.…”

Section: Introductionmentioning

confidence: 99%

Effect of alloy substituents on soft magnetic properties and economics of Fe-based and Co-based alloys

2015

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Amorphous and nanocrystalline soft magnetic alloys have garnered interests in academia and industry due to their potentials for applications, such as power transformers, electric motors, and sensors. To achieve good glass formability, thermal stability, and prevent grain overgrowth, elements such as B, Nb, Ta, and Hf are used in many soft magnetic systems. However, the high price of these precursors results in expensive soft magnetic alloys. Herein, we report on substituting Ta and Hf with TaC and HfC, respectively, to significantly reduce the cost of Fe-based FINEMET and Co-based HTX005 alloys. Soft magnetic properties of these alloys are studied. The effect of thermal annealing and strain annealing on TaC and HfC substituted alloys are also investigated. Lastly, we discuss the cost analysis on these alloys. Using the synthesis route presented here, a cost reduction of up to 74% can be achieved.

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Nanocrystalline Hf and Ta containing FeCo based alloys for high frequency applications

Cited by 28 publications

References 21 publications

A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

Reduced losses in rolled Fe73.5Si15.5Nb3B7Cu1 nanocrystalline ribbon

Effect of alloy substituents on soft magnetic properties and economics of Fe-based and Co-based alloys

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