Synthesizing the Hard Magnetic Low-Temperature Phase of MnBi Alloy: Challenges and Prospects

The low-temperature phase (LTP) of the binary MnBi alloy system is well recognized for its potential to yield the highest maximum energy product value among the rare earth element-free permanent magnets. However, studies have revealed that the magnetic properties of LTP-MnBi are extremely sensitive to the purity of the LTP phase, and the major challenge lies in the formulation and selection of the appropriate processing techniques for preparing pure LTP-MnBi. During the last 2 decades, up-gradation in the purity of LTP-MnBi has been achieved through the development of new preparation methods. A review is presented on the recent advancements made in developing high-purity LTP-MnBi through the newly developed routes and the effect of the process parameters on the purity, physical and magnetic properties of the LTP-MnBi system.