Magnetic properties of MnBi1−xRx (R=rare earth) systems

Abstract

MnBi crystallizes in a NiAs-type hexagonal crystal structure, exhibits a high uniaxial anisotropy, and is potentially useful as a permanent magnet material. We have examined the effect of partial substitution of Bi with rare earth elements on the magnetic properties of MnBi. MnBi1−xRx (R=Nd, Dy) were prepared by mechanically alloying powders of the constituent elements at liquid nitrogen temperature followed by heat treatment. X-ray diffraction and magnetic measurements were performed on powder samples to characterize the samples. We found that in MnBi1−xNdx, coercivity (at room temperature) increases from 0.7 kOe to 6.6 kOe for x=0.0 and 0.3, respectively. In MnBi1−xDyx the coercivity increases from 0.7 kOe to 7.9 kOe for x=0.0 and 0.3. The increase in coercivity may be in part due to the increase in the crystal field anisotropy as Nd or Dy is introduced and in part due to the finer particle size. A magnet made from MnBi shows coercivity of ∼17 kOe. A very fine particle size is considered to be the reason for this high coercivity.

Structure and magnetic properties of the MnBi low temperature phase

“…[7][8][9] Many efforts have been made to produce single phase MnBi. [7][8][9][10][11][12][13][14][15] At present, no single phase MnBi has been prepared by sintering Mn and Bi powders.…”

Magnetic and Structural Properties of MnBi1-xTixAlloys

“…In Fig. 2, the increase of magnetization with cooling, compared with that with heating, is most likely due to the formation of more LTP, as the sample passes through the heat treatment [16]. In MnTi sample, as shown in Fig.…”

Unusual Lattice‐Magnetism Connections in MnBi Nanorods

“…HTP MnBi of nominal composition Mn 1.08 Bi possesses either paramagnetic or antiferromagnetic character. [23,24] The bulk magnetostructural transition is thermodynamically first order and exhibits hysteresis in both field and temperature, [25,26] although controversy concerning the nature of the phase transformation persists. [27] Data on the thermal expansion and lattice parameter evolution with temperature of bulk MnBi are only available from older publications, published by Willis and Rooksby in 1954 and by Roberts in 1956.…”