Evaluation of structural and magnetic property of Cr-doped MnBi permanent magnet material

Abstract

In the present study, the effects of doping on the LTP-MnBi phase formation as well as on Mn to Bi ratio in the matrix were investigated. Structural- and magnetic properties of nanocrystalline Mn50−xBi50Crx (x = 0, 1.5, 3, 5) permanent magnet material, prepared by melt-spinning were studied and correlated with the thermal analysis. A more stabilized LTP-MnBi phase is formed with Cr doping. A large enhancement in the coercivity along with magnetization is observed with Cr doping. A magnetization of 54.2 emu/g and a coercivity value of 11.9 kOe were obtained for the composition Mn47Bi50Cr3 at room temperature, which increases to 17.5 kOe at 150 °C. An interesting correlation exists between the thermal as well as the structural- and magnetic properties of the compound. Also, a decrease in magnetic transition temperature is observed in Cr-doped samples, which has been studied in detail. This decrease in magnetic transition temperature helps in the decoupling of structural- and magnetic transition temperature, thereby leading to a formation of more stable LTP-MnBi compound.