Prusty Mitali Madhusmita, Molleti Sri Harsha, Takanobu Hiroto, Malladi Sai Rama Krishna, Tang Xin, Sepehri-Amin Hossein
Green Magnetic Material Group, Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, Tsukuba, Japan.
Department of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, India.
Sci Technol Adv Mater. 2025 Jun 30;26(1):2525742. doi: 10.1080/14686996.2025.2525742. eCollection 2025.
Magnetic cooling technology, based on the magnetocaloric effect (MCE), offers an energy-efficient and eco-friendly alternative to conventional gas compression, but is often hindered by large magnetic hysteresis, which limits cyclic performance. In this study, we show that the hysteresis of LaCe(Fe,Si)₁₃ hydrides - a promising material for room-temperature refrigeration - can be significantly reduced by refining the microstructure of the precursor alloy. Substituting Ce for La in (LaCe)(Fe,Si)H increases hysteresis losses from 12.3 J/kg to 34 J/kg. However, preparing the precursor alloy using the melt-spinning technique can almost eliminate this hysteresis. Lorentz transmission electron microscopy (Lorentz-TEM) shows that phase transition nucleation preferentially occurs at the grain boundaries. The hydrides prepared from melt-spun ribbons exhibit a much larger volume fraction of grain boundaries due to finer grains, providing a higher density of nucleation sites. This reduces the energy barrier for the phase transition and weakens the magneto-structural phase transition, as confirmed by X-ray diffraction patterns. Consequently, the reduced phase transition energy barrier leads to significantly lower hysteresis in melt-spun hydrides samples. These findings demonstrate the potential of microstructure engineering to reduce hysteresis in (La,Ce)(Fe,Si)Hₓ materials for room-temperature magnetocaloric applications.
基于磁热效应（MCE）的磁制冷技术为传统气体压缩提供了一种节能且环保的替代方案，但通常会受到大磁滞的阻碍，这限制了循环性能。在本研究中，我们表明，通过细化前驱体合金的微观结构，可以显著降低LaCe(Fe,Si)₁₃氢化物（一种用于室温制冷的有前景的材料）的磁滞。在(LaCe)(Fe,Si)H中用Ce替代La会使磁滞损耗从12.3 J/kg增加到34 J/kg。然而，使用熔体纺丝技术制备前驱体合金几乎可以消除这种磁滞。洛伦兹透射电子显微镜（Lorentz-TEM）表明，相变形核优先发生在晶界处。由于晶粒更细，由熔体纺丝带制备的氢化物具有更大的晶界体积分数，提供了更高密度的形核位点。这降低了相变的能垒并削弱了磁结构相变，X射线衍射图谱证实了这一点。因此，降低的相变能垒导致熔体纺丝氢化物样品中的磁滞显著降低。这些发现证明了微观结构工程在降低用于室温磁热应用的(La,Ce)(Fe,Si)Hₓ材料中的磁滞方面的潜力。
