Song Yuzhu, Sun Qiang, Yokoyama Toshihiko, Zhu Huihui, Li Qiang, Huang Rongjin, Ren Yang, Huang Qingzhen, Xing Xianran, Chen Jun
Beijing Advanced Innovation Center for Materials Genome Engineering and Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China.
J Phys Chem Lett. 2020 Mar 5;11(5):1954-1961. doi: 10.1021/acs.jpclett.9b03880. Epub 2020 Feb 25.
Negative thermal expansion (NTE) is an intriguing property for not only fundamental studies but also technological applications. However, few NTE materials are available compared with the huge amount of positive thermal expansion materials. The discovery of new NTE materials remains challenging. Here we report a chemical modification strategy to transform thermal expansion from positive to negative in cubic magnetic compounds of (Zr,Nb)Fe by tuning the magnetic exchange interaction. Furthermore, an isotropic zero thermal expansion can be established in ZrNbFe (α = 1.4 × 10 K, 3-470 K) over a broad temperature range that is even wider than that of the prototype Invar alloy of FeNi. The NTE of (Zr,Nb)Fe is originated from the weakened magnetic exchange interaction and the increased d electrons of Fe by the Nb chemical substitution, so that the magnetovolume effect overwhelms the contribution of anharmonic lattice vibration.
负热膨胀（NTE）不仅是基础研究中的一个有趣特性，也是技术应用中的一个有趣特性。然而，与大量的正热膨胀材料相比，可用的NTE材料很少。发现新的NTE材料仍然具有挑战性。在这里，我们报告了一种化学改性策略，通过调节磁交换相互作用，将（Zr，Nb）Fe立方磁性化合物中的热膨胀从正转变为负。此外，在ZrNbFe（α = 1.4 × 10 K，3 - 470 K）中，可以在比原型FeNi因瓦合金更宽的温度范围内建立各向同性的零热膨胀。（Zr，Nb）Fe的NTE源于Nb化学取代导致的磁交换相互作用减弱和Fe的d电子增加，从而使磁体积效应超过非谐晶格振动的贡献。
