Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

Abstract

MnBi attracts great attention in recent years for its great potential as permanent magnetmaterials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ B at 50 K and 300 K, respectively. MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 l B at 50 K and 300 K, respectively. V C 2014 AIP Publishing LLC.

Magnetic properties of(Fe1−xCox)2Balloys and the effect of doping byEdström1, Werwiński2, Iuşan3 et al. 2015Phys. Rev. B

“…Recently, however, the availability (and thus price) of the rare-earth elements became rather volatile, calling for development of replacement materials which would use less or none of * Corresponding author: jan.rusz@physics.uu.se the rare-earth elements. Intense research efforts have started worldwide, revisiting previously known materials, such as Fe 2 P [5][6][7], FeNi [8], or Fe 16 N 2 [9], doing computational data mining among the large family of Heusler alloys [10], exploring the effects of strain [11][12][13][14][15][16][17] and doping by interstitial elements [18,19], multilayers such as Fe/W-Re [20] or, as a limiting case of multilayers, the L1 0 family of compounds [21], or promising Mn-based systems [22][23][24][25][26][27], among others.…”

Effect of composition and heat treatment on MnBi magnetic materials

“…The composition, lattice structure and parameters for the HTP phase are Mn 2.23 Bi 1.88 , Pmma, and a = 0.5959 nm, b = 0.4334 nm, c = 0.7505 nm, a = b = c = 90°, respectively [2]. For the LTP phase, they are Mn 50 Bi 50 , P63/mmc, and a = b = 0.4290 nm, c = 0.6126 nm, a = b = 90°, c = 120°, respectively [3][4][5]. The LTP MnBi has a high magnetocrystalline anisotropy (1.6 Â 10 6 J m À3 ), and a relatively low saturation magnetization (81 emu g À1 , $9 kG) at 300 K [6].…”

Processing of MnBi bulk magnets with enhanced energy product

“…Past studies of MnBi materials have proven that it is extremely difficult to prepare a pure LT MnBi phase in large scale by conventional methods. [5][6][7][8][9][10][13][14][15][16][17][18][19][20][21][22][23][24] The single LTP MnBi formation is impeded by the Mn segregation from the Mn-Bi liquid at the peritectic temperature and the extremely slow diffusion of Mn to combine with Bi for forming MnBi at low annealing temperature (T a < 613 K). 9,25 Recently, we have reported our new efforts in preparing a MnBi bulk magnets with a good balance of remanence and coercivity via a novel processing route with (BH) max value of 7.8 MGOe at room temperature.…”