12010-50-3Relevant academic research and scientific papers
Synthesis and characterization of rare-earth-free magnetic manganese bismuth nanocrystals
Shen, Jian,Cui, Huizhong,Huang, Xiaopeng,Gong, Maogang,Qin, Wei,Kirkeminde, Alec,Cui, Jun,Ren, Shenqiang
, p. 5567 - 5570 (2015)
Earth abundant manganese bismuth (MnBi) has long been of interest due to its large magnetocrystalline anisotropy and high energy density for advanced permanent magnet applications. However, solution synthesis of MnBi phase is challenging due to the reduction potential mismatch between Mn and Bi elements. In this study, we show a versatile MnBi synthesis method involving the metal co-reduction followed by thermal annealing. The magnetically hard MnBi crystalline phase is then exchange coupled with magnetically soft cobalt coating. Our processing approach offers a promising strategy for manufacturing rare-earth-free magnetic nanocrystals. This journal is
Decoupling the structural and magnetic phase transformations in magneto-optic MnBi thin films by the partial substitution of Cr for Mn
Bandaru, Prabhakar R.,Sands, Timothy D.,Kubota, Yukiko,Marinero, Ernesto E.
, p. 2337 - 2339 (1998)
The first-order nature of the magnetic phase transformation at 360°C and the presence of a Bi-rich eutectic at 265°C have inhibited the application of MnBi thin films for high density magneto-optical data storage. It is suggested that partial substitution of Cr for Mn should both lower the Curie temperature, Tc, and decouple the lattice and magnetic transitions so as to allow reversible Curie point writing. It is found experimentally that 10% substitution of Cr for Mn reduces the apparent Tc to ～250°C while retaining a Kerr rotation angle greater than 1° at 633 nm, as measured through the silica glass substrate. Observations of increasing Hc with temperature in both MnBi and (Mn,Cr)Bi thin films suggest that the low-temperature phase is ferrimagnetic.
Change of the equilibrium state of ferromagnetic MnBi by high magnetic fields
Koyama, Keiichi,Mitsui, Yoshifuru,Choi, Eun Sang,Ikehara, Yuki,Palm, Eric C.,Watanabe, Kazuo
, p. L78-L80 (2011)
Differential thermal analysis was carried out for ferromagnetic material MnBi in the temperature range 300-773 K in magnetic fields up to 45 T to investigate the effect of high magnetic fields on its decomposition process and corresponding phase diagram.
FORMATION PROCESS OF MnBi THIN FILMS BY WILLIAMS' METHOD.
Iwama,Takeno
, p. 75 - 83 (1983)
When Mn and Bi are successively evaporated on a glass substrate followed by prolonged annealing around 300 degree C, a ferromagnetic thin film can be obtained with its c axis perpendicular to the film plane. In order to elucidate the formation process. Rutherford backscattering experiments X-ray diffractometry, electron microscope studies and magnetic measurements were carried out. At the first stage of annealing up to 250 degree C, a non-magnetic transitional compound Mn//1//. //2Bi is formed. During subsequent annealing at 250 degree C, the final crystals with aligned c axes nucleate and grow at the expense of the transitional phase. At the last stage of the reaction, a few Bi crystals remaining in the transitional phase may serve as nuclei.
Anisotropic nanocrystalline MnBi with high coercivity at high temperature
Yang,Yang,Chen,Ma,Han,Yang,Guo,Yan,Huang,Wu,Chen
, (2011)
Magnetic hard nanocrystalline MnBi has been prepared by melt spinning and subsequent low temperature annealing. A coercivity of 2.5 T can be achieved at 540 K for MnBi with an average grain size of about 20-30 nm. The coercivity iHc, mainly controlled by the coherent magnetization rotation, shows a strong dependence on the time of grinding and exhibits a positive temperature coefficient from 100 up to 540 K. The unique temperature dependent behavior of the coercivity (magnetocrystalline anisotropy) has a relationship with the variations in the crystal lattice ratio of c/a with temperatures. In addition, discontinuity can not be found in the lattice parameters of a, c, and c/a ratio at the magnetostructural transition temperature. The nanocrystalline MnBi powder fixed in an epoxy resin and under an applied magnetic field of 24 kOe shows a maximum energy product of 7.1 MGOe at room temperature and shows anisotropic characteristics with high Mr/Ms ratio up to 560 K.
Spin reorientation in MnBi
Yoshida,Shima,Takahashi,Fujimori,Abe,Kaneko,Kanomata,Suzuki
, p. 297 - 301 (2001)
High purity MnBi was prepared by arc-melting under He gas. The prepared samples have the property of being hard to oxidize in air and progress of oxidation was not observed by X-ray diffraction 1 year later. It is easy to pulverize a good quality sample into powder even in air. We confirmed that coercive force at room temperature depends on the powder size and takes a value of 8 kOe for less than 400 mesh. The permeability has a hysteresis in a temperature range between 77 and 300 K and exhibits a maximum at 100 K corresponding to the spin reorientation temperature Tt. The pressure (P) dependence of Tt was examined by measuring the permeability at various pressures. The value of dTt/dP was obtained to be 9.6 K/kbar. The results of thermal expansion revealed that both the lattice parameters a and c increase abruptly near 250 K.
Alignment and analyses of MnBiBi nanostructures
Kang,Lewis,Moodenbaugh
, (2005)
A Mn5 Bi95 alloy was rapidly solidified into a mixture of nanocrystalline Bi and metastable Bi(Mn). Heating the ribbons to temperature T=525 K in a dc magnetic field causes formation and c -axis alignment of low-temperature phase (LTP) MnBi nanorods along the applied field direction. Nanorod alignment increases with increased magnetic field, with a calculated alignment half-angle of 47° for a sample heated to 520 K at 50 kOe. In situ magnetization changes suggest that nanorod alignment is achieved by rotation of MnBi particles. Particle alignment enables the measurement of the MnBi nanorod spin reorientation temperature of 100 K, the same as its bulk counterpart.
Large magnetoresistance in MnBi point contacts
Clifford,Venkatesan,Coey
, p. 1614 - 1615 (2004)
An MnBi alloy was produced by arc melting under helium followed by annealing. Point contacts were then created in a piezosystem using small crystals taken from the bulk sample. The I:V curves were then measured with and without an applied field. Large magnetoresistances (ΔR/R 0>70%) in a field of 10mT were observed in some cases.
Effect of a high magnetic field on the morphology and magnetic properties of the MnBi compound during the Mn1.08Bi-MnBi phase transformation process
Li, Xi,Ren, Zhongming,Fautrelle, Yves,Deng, Kang
, p. 2694 - 2700 (2009)
Effect of a 10 T high magnetic field on the morphology and magnetic properties of the MnBi compounds during the Mn1.08Bi-MnBi phase transformation has been investigated. Results indicate that the field has split the MnBi crystal along the (0 0
Magnetic-field-induced enhancement for synthesizing ferromagnetic MnBi phase by solid-state reaction sintering
Mitsui, Yoshifuru,Umetsu, Rie Y.,Koyama, Keiichi,Watanabe, Kazuo
, p. 131 - 134 (2014)
Ferromagnetic MnBi was synthesized by a solid-state reaction sintering method in high magnetic fields up to 15 T. The fraction of ferromagnetic MnBi phase in the sample sintered at 15 T was about 70% by weight, which was much larger than that sintered in a zero magnetic field. It was found that high magnetic fields dramatically enhanced the formation of MnBi phase from bismuth and manganese. In addition, the c-axis of a hexagonal structure of MnBi was oriented parallel to the magnetic field direction. These magnetic field effects on the synthesizing process were examined based on the gain of the Zeeman energy and the uniaxial magnetic anisotropy of MnBi phase.
