ABSTRACT

Multielement rare earth (R)–transition metal (T) intermetallics are arguably the next generation of high-performance permanent magnetic materials for future applications in energy-saving and renewable energy technologies. Pseudobinary Sm₂Fe₁₇N₃ and (R,Zr)(Fe,Co,Ti)₁₂ (R = Nd, Sm) compounds have the highest potential to meet current demands for rare-earth-element-lean permanent magnets (PMs) with ultra-large energy product and operating temperatures up to 200°C. However, the synthesis of these materials, especially in the mesoscopic scale for maximizing the maximum energy product (${\left(BH\right)}_{\mathrm{m}\mathrm{a}\mathrm{x}}$), remains a great challenge. Nonequilibrium processes are apparently used to overcome the phase-stabilization challenge in preparing the R–T intermetallics but have limited control of the material’s microstructure. More radical bottom-up nanoparticle approaches based on chemical synthesis have also been explored, owing to their potential to achieve the desired composition, structure, size, and shape. While a great achievement has been made for the Sm₂Fe₁₇N₃, progress in the synthesis of (R,Zr)(Fe,Co,Ti)₁₂ magnetic mesoscopic particles (MMPs) and R–T/T exchange-coupled nanocomposites (NCMs) with substantial coercivity ($H_{\mathrm{c}}$) and remanence ($M_{\mathrm{r}})$, respectively, remains marginal.

摘要

多元素稀土（R）-过渡金属（T）金属间化合物可以说是下一代高性能永磁材料，可用于节能和可再生能源技术的未来应用。伪二元Sm ₂ Fe ₁₇ N ₃和（R，Zr）（Fe，Co，Ti）₁₂（R = Nd，Sm）化合物具有最高的潜力，可以满足目前对贫稀土元素永磁体（PMs）的需求具有超大型能源产品，工作温度高达200°C。但是，这些材料的合成，尤其是在介观尺度上的合成，以最大程度地提高最大能量乘积（${\left(乙H\right)}_{\mathrm{米}\mathrm{一种}\mathrm{X}}$），仍然是一个巨大的挑战。显然，非平衡工艺可用来克服制备R–T金属间化合物的相稳定挑战，但对材料的微观结构的控制有限。由于它们具有实现所需组成，结构，尺寸和形状的潜力，因此还探索了基于化学合成的更彻底的自下而上的纳米粒子方法。尽管Sm ₂ Fe ₁₇ N ₃取得了巨大成就，但（R，Zr）（Fe，Co，Ti）₁₂磁介观粒子（MMPs）和R–T / T交换耦合纳米复合材料的合成取得了进展。（NCMs）具有很大的矫顽力（$H_{\mathrm{C}}$）和剩余（${\mathrm{中号}}_{\mathrm{[R}}）$分别保持边际。