Preparation of Highly Pure MnBi Intermetallic Compounds by Arc-Melting

Yoshida, Hajime; Shima, T.; Takahashi, T.; Fujimori, H.

doi:10.2320/matertrans1989.40.455

Cited by 58 publications

(31 citation statements)

References 8 publications

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“…The lattice parameters a and c were determined to be 0.4310 nm and 0.6076 nm at RT, respectively, which are comparable to the reported data of the LTP phase. 4,5,[7][8][9][10][11][12] Using a Farady-force magnetometer, magnetization M was measured in the temperature range from 300 to 620 K and in magnetic fields up to 10 T. The experimental setup of the magnetization measurements was described in Ref. 13) in detail.…”

Section: Methodsmentioning

confidence: 99%

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

et al. 2007

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Magnetization measurements and differential thermal analysis (DTA) of polycrystalline MnBi were carried out in magnetic fields up to 14 T and in 300-773 K, in order to investigate the magnetic phase transition. The magnetic phase transition temperature (T t ) at a zero magnetic field is 628 K and linearly increases with increasing fields up to 14 T at the rate of 2 KT À1 . A metamagnetic transition between the paramagnetic and field-induced ferromagnetic states was observed just above T t . The exothermic and endothermic peaks were detected in the magnetic field dependence of DTA signals in 626-623 K, which relates to the metamagnetic transition. The obtained results were discussed on the basis of a mean field theory.

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Section: Methodsmentioning

confidence: 99%

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

et al. 2007

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“…A rather drastic peritectic reaction exists over wide temperature and composition ranges. Several methods have been utilized in preparation of high purity MnBi single phase, including arc-melting, sintering, and melt-spin rapid solidification [4,[8][9][10][11]. Among them, only rapid solidification was able to consistently produce over 90% pure MnBi single phase.…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of MnBi magnetic materials

Cui

Choi

et al. 2014

J. Phys.: Condens. Matter

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MnBi has attracted much attention in recent years due to its potential as a rare-earth-free permanent magnet material. It is unique because its coercivity increases with increasing temperature, which makes it a good hard phase material for exchange coupling nanocomposite magnets. MnBi phase is difficult to obtain, partly because the reaction between Mn and Bi is peritectic, and partly because Mn reacts readily with oxygen. MnO formation is irreversible and harmful to magnet performance. In this paper, we report our efforts toward developing MnBi permanent magnets. To date, high purity MnBi (>90%) can be routinely produced in large quantities. The produced powder exhibits 74.6?emu?g?1 saturation magnetization at room temperature with 9?T applied field. After proper alignment, the maximum energy product (BH)max of the powder reached 11.9?MGOe, and that of the sintered bulk magnet reached 7.8?MGOe at room temperature. A comprehensive study of thermal stability shows that MnBi powder is stable up to 473?K in air. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. AbstractMnBi has attracted much attention in recent years due to its potential as a rare-earth-free permanent magnet material. It is unique because its coercivity increases with increasing temperature, which makes it a good hard phase material for exchange coupling nanocomposite magnets. MnBi phase is difficult to obtain, partly because the reaction between Mn and Bi is peritectic, and partly because Mn reacts readily with oxygen. MnO formation is irreversible and harmful to magnet performance. In this paper, we report our efforts toward developing MnBi permanent magnets. To date, high purity MnBi (>90%) can be routinely produced in large quantities. The produced powder exhibits 74.6 emu g −1 saturation magnetization at room temperature with 9 T applied field. After proper alignment, the maximum energy product (BH) max of the powder reached 11.9 MGOe, and that of the sintered bulk magnet reached 7.8 MGOe at room temperature. A comprehensive study of thermal stability shows that MnBi powder is stable up to 473 K in air.

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“…As shown in Fig. 2(a), with the increase of temperature, magnetization of MnBi alloy decreases slightly, reaches minimum value at around 497 K, and then increases gradually up to 590 K. Increase of magnetization with temperature is considered to be due to increasing the volume fraction of LTP MnBi, which possesses a higher magnetization value [8]. The increase of magnetization above 500 K is due to the formation of the LTP of MnBi [14].…”

Section: Resultsmentioning

confidence: 94%

“…Many efforts have been made to produce single-phase MnBi. Yoshida et al [8] prepared the MnBi magnet with about 90 wt.% LTP by zone-arc-melting under He atmosphere, followed by heat treatment. The Curie temperature was measured at 633 K. Furthermore, fine powders obtained by grinding the strongly orientated bulk possess a large coercivity of 0.7 T, and this large coercivity is considered to be due to the large crystalline anisotropy of the particles in the single domain state.…”

Section: Introductionmentioning

confidence: 99%

Magnetic and Structural Properties of MnBi_1-xTi_xAlloys

Zhang¹,

Zhang²,

H.C.Jiang³

et al. 2014

Journal of Magnetics

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MnBi 1-x Ti x (x = 0, 0.4, 0.7, 1) alloys were prepared by arc-melting, followed by heat treatment. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) were used to measure and investigate the phase structure and magnetic properties. The temperature dependent magnetization curves indicate that the phase transitions between LTP and HTP MnBi occur with heating or cooling in MnBi 1-x Ti x (x ≤ 0.7) samples. However, MnTi samples are in Mn 2 Ti single-phase, with very low magnetic properties. Furthermore, the coercivity exhibits a positive temperature coefficient. The results show that the optimal content of Ti for the coercivity of MnBi 1-x Ti x alloy is x = 0.4. For MnBi sample, the coercivity reaches a maximum value of 1.13 T at 550 K. However, the remanence and energy product show apparent decrease with the addition of Ti in MnBi 1-x Ti x alloys.

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Preparation of Highly Pure MnBi Intermetallic Compounds by Arc-Melting

Cited by 58 publications

References 8 publications

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

Thermal stability of MnBi magnetic materials

Magnetic and Structural Properties of MnBi_1-xTi_xAlloys

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Preparation of Highly Pure MnBi Intermetallic Compounds by Arc-Melting

Cited by 58 publications

References 8 publications

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

Magnetic Phase Transition of MnBi under High Magnetic Fields and High Temperature

Thermal stability of MnBi magnetic materials

Magnetic and Structural Properties of MnBi1-xTixAlloys

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Product

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Magnetic and Structural Properties of MnBi_1-xTi_xAlloys