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.

中文翻译：

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MnBi合金硬磁低温相的合成：挑战与展望

二元MnBi合金系统的低温相（LTP）因其在不含稀土元素的永磁体中产生最高能量积值的潜力而广为人知。然而，研究表明，LTP-MnBi 的磁性对 LTP 相的纯度极为敏感，主要挑战在于制备纯 LTP-MnBi 的合适工艺技术的配方和选择。在过去的 20 年里，通过开发新的制备方法，LTP-MnBi 的纯度不断提高。综述了通过新开发的路线开发高纯度 LTP-MnBi 的最新进展以及工艺参数对 LTP-MnBi 系统纯度、物理和磁性能的影响。