التفاصيل البيبلوغرافية
| العنوان: |
Anomalous thermal expansion and enhanced magnetocaloric effect in <001>-textured MnxFe5–xSi3 alloys. |
| المؤلفون: |
Gong, Yong, Miao, Xue-Fei, Samanta, Tapas, Taake, Chris, Liu, Jun, Qian, Feng-Jiao, Shao, Yan-Yan, Zhang, Yu-Jing, Ren, Qing-Yong, Caron, Luana, Xu, Feng |
| المصدر: |
Rare Metals; May2024, Vol. 43 Issue 5, p2263-2274, 12p |
| Abstract (English): |
The development of zero and negative thermal expansion (i.e., ZTE and NTE) materials is of crucial importance to the control of undesirable thermal expansion for high-precision devices. In the present work, ZTE and NTE were obtained in directionally-solidified MnxFe5–xSi3 alloys with a strong <001> texture, in striking contrast to positive thermal expansion in their isotropic counterparts. Magnetometry and in-situ X-ray diffraction (XRD) measurements were performed to uncover the origin of the anomalous thermal expansion. Magnetic measurements indicate a strong easy-plane magnetocrystalline anisotropy in the textured samples, where the magnetic moments are aligned within the ab plane of the hexagonal structure. Temperature-dependent XRD on the x = 1 sample reveals a ZTE character in the ab plane that is coupled to a ferromagnetic transition. As a result, the macroscopic ZTE (~ 0.22 × 10–6 K−1) in the x = 1 sample can be attributed to the microscopic magneto volume effect within the ab plane, which is realized by the introduction of the <001>-textured microstructure. Besides, the competition between antiferromagnetic and ferromagnetic exchange coupling leads to NTE in textured x = 1.5 and 2 samples. Additionally, textured x = 1 sample displays enhanced magnetocaloric properties as compared to the conventional counterparts with randomly-oriented grains. Consequently, this work demonstrates a new strategy toward the exploration of anomalous thermal expansion properties as well as the enhancement of magnetocaloric properties for materials with a strong magnetocrystalline anisotropy. [ABSTRACT FROM AUTHOR] |
| Abstract (Chinese): |
摘要: 零热膨胀和负热膨胀 (即ZTE和NTE) 材料对于控制精密元器件的尺寸稳定性至关重要。本研究通过定向凝固技术制备了具有 < 001 > 织构的MnxFe5–xSi3 合金, 获得了常规各向同性样品不具有的ZTE和NTE性能。进一步利用磁测量和原位X 射线衍射(XRD) 研究了其反常热膨胀的物理起源。磁测量表明, MnxFe5–xSi3系列样品具有较强的磁晶各向异性, 磁矩沿着六方结构的 ab 面排列。变温 XRD结果表明, x = 1 样品的六方晶胞在ab 面内呈现出ZTE, 并且该ZTE行为与铁磁相变同时发生。因此, x = 1 样品的宏观 ZTE (~ 0.22 × 10–6 K−1)来源于ab 面内的微观磁体积效应与晶粒择优取向的协同作用。x = 1.5和2样品中反铁磁与铁磁交换作用之间的相互竞争进一步增强了磁体积效应, 使得其呈现出NTE。 此外, 与常规各向同性样品相比, 晶粒择优取向样品表现出更强的磁热效应。 因此, 本研究提供了一种开发反常热膨胀材料的新思路以及增强磁热效应的新策略。 [ABSTRACT FROM AUTHOR] |
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