Tahir Shabbir, Smoliarova Tatiana, Doñate-Buendía Carlos, Farle Michael, Shkodich Natalia, Gökce Bilal
Chair of Materials Science and Additive Manufacturing, University of Wuppertal, Gaußstr. 20, 42119 Wuppertal, Germany.
Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany.
Beilstein J Nanotechnol. 2025 Jun 5;16:823-836. doi: 10.3762/bjnano.16.62. eCollection 2025.
Magnetic phase transitions at the Curie temperature are essential for applications like magnetocaloric refrigeration, magnetic sensors, and actuators, but the reliance on costly, scarce rare-earth materials limits sustainability. Developing affordable, rare-earth-free materials with tunable magnetic properties and scalable miniaturization methods is vital for advancing technology. We present a comprehensive synthesis approach for rare-earth-free compositionally complex alloys (CCAs) with magnetic phase transitions, spanning from bulk materials to nanoparticles. Specifically, we investigate MnFeNiGeSi (Ge-based CCA) and MnFeNiSiAl (Al-based CCA). The bulk materials are prepared by ball milling and spark plasma sintering or powder pressing and sintering. Nanoparticles (NPs) from the bulk materials are synthesized by pulsed laser ablation in liquid. Magnetization measurements confirm a ferromagnetic-to-paramagnetic phase transition in bulk alloys, with = 179 K for Ge-based CCA and = 263 K for Al-based CCA. At the nanoscale, both Ge- and Al-based NPs exhibit superparamagnetic behaviour, with blocking temperatures of ≈ 120 K for Ge-based NPs ( = 13.4 ± 15.5 nm, average particle size) and ≈ 100 K for Al-based NPs ( = 18.4 ± 9.1 nm, average particle size), demonstrating the intrinsic superparamagnetic nature of NPs. While the Ge-based CCA demonstrates almost twice the saturation magnetization ( ) and ≈20% lower hysteresis ( ) in bulk form, the Al-based CCA exhibits comparable and ≈45% lower at the nanoscale at 5 K. These results indicate that the Al-based CCA is a promising, cost-effective alternative to Ge-based CCA at nanoscale, providing an economically viable and cost-effective alternative for nanoscale-based applications.
居里温度下的磁相变对于磁热制冷、磁传感器和致动器等应用至关重要，但对昂贵、稀缺的稀土材料的依赖限制了可持续性。开发具有可调磁性能且可扩展的小型化方法的经济适用、无稀土材料对于推动技术发展至关重要。我们提出了一种用于具有磁相变的无稀土成分复杂合金（CCA）的综合合成方法，涵盖从块状材料到纳米颗粒。具体而言，我们研究了MnFeNiGeSi（基于Ge的CCA）和MnFeNiSiAl（基于Al的CCA）。块状材料通过球磨和放电等离子烧结或粉末压制与烧结制备。通过液体中的脉冲激光烧蚀从块状材料合成纳米颗粒（NP）。磁化测量证实了块状合金中从铁磁到顺磁的相变，基于Ge的CCA的居里温度为179 K，基于Al的CCA的居里温度为263 K。在纳米尺度上，基于Ge和基于Al的NP均表现出超顺磁行为，基于Ge的NP（平均粒径 = 13.4 ± 15.5 nm）的阻塞温度约为120 K，基于Al的NP（平均粒径 = 18.4 ± 9.1 nm）的阻塞温度约为100 K，证明了NP的固有超顺磁性质。虽然基于Ge的CCA在块状形式下的饱和磁化强度（ ）几乎是两倍，磁滞（ ）低约20%，但基于Al的CCA在5 K时在纳米尺度上具有相当的 且磁滞低约45%。这些结果表明，基于Al的CCA在纳米尺度上是基于Ge的CCA的一种有前景、经济高效的替代品，为基于纳米尺度的应用提供了经济可行且成本效益高的选择。
