Thermal stability of MnBi magnetic materials

Zarkevich, Nikolai; Choi, J. P.; Johnson, Duane; Polikarpov, E.; Darsell, J.; Overman, N.; Olszta, M.; Schreiber, D.; Bowden, M.; Droubay, T.; Kramer, Matthew; Wang, Linlin; Johnson, Duane; Marinescu, M.; Takeuchi, I.; Huang, Q. Z.; Wu, H.; Reeve, H.; Vuong, N. V.; Liu, J.

Thermal stability of MnBi magnetic materials

File

2014_Cui_ThermalStability.pdf (1.78 MB)

Date

2014-01-01

Authors

Zarkevich, Nikolai

Choi, J. P.

Johnson, Duane

Polikarpov, E.

Darsell, J.

Overman, N.

Olszta, M.

Schreiber, D.

Bowden, M.

Droubay, T.

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Authors

Person

Zarkevich, Nikolai

Person

Johnson, Duane

Distinguished Professor

Organizational Units

Organizational Unit

Ames National Laboratory

Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.

For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.

Organizational Unit

Materials Science and Engineering

Materials engineers create new materials and improve existing materials. Everything is limited by the materials that are used to produce it. Materials engineers understand the relationship between the properties of a material and its internal structure — from the macro level down to the atomic level. The better the materials, the better the end result — it’s as simple as that.

Department

Ames National LaboratoryMaterials Science and Engineering

Abstract

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.

Comments

This article is from Journal of Physics: Condensed Matter 26 (2014): 064212, doi:10.1088/0953-8984/26/6/064212.