Li Yuan, Gao Qilong, Chang Dahu, Sun Pengju, Liu Junzhe, Jia Yu, Liang Erjun, Sun Qiang
Key Laboratory of Materials Physics , Ministry of Education International Laboratory for Quantum Functional Materials of Henan, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, People's Republic of China.
Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023, People's Republic of China.
J Phys Condens Matter. 2020 Aug 13;32(45). doi: 10.1088/1361-648X/aba777.
Negative thermal expansion (NTE) is an abnormal physical behavior that has promising applications for high precision thermal control. Since Prussian blue analogues have the two central linking atoms of -C≡N-, they have large structure flexibility and are suitable to explore new NTE materials. However, understanding the nature of structure flexibility from the point of view of chemical bonding is important and urgent. Here, we adopt for the first time first-principles calculations to predict that the cubic TiCo(CN)and ScCo(CN)have NTE behavior. The calculated results for M in MCo(CN)(M = Fe, Ti and Co) indicated that the Sc-N bond is the strongest, but with the weakest direction dependence among the M-N bonds in the three systems. The lattice dynamics calculations results revealed that the low-frequency phonon vibration modes for NTE in MCo(CN)have much stronger relationship with the M-N bond feature. The present work reveals the important role of the related bond in the NTE open-framework materials.
负热膨胀（NTE）是一种异常的物理行为，在高精度热控制方面具有广阔的应用前景。由于普鲁士蓝类似物具有-C≡N-这两个中心连接原子，它们具有很大的结构灵活性，适合于探索新型NTE材料。然而，从化学键的角度理解结构灵活性的本质既重要又紧迫。在此，我们首次采用第一性原理计算预测立方相TiCo(CN)和ScCo(CN)具有NTE行为。对MCo(CN)（M = Fe、Ti和Co）中M的计算结果表明，Sc-N键最强，但在这三个体系的M-N键中，其方向依赖性最弱。晶格动力学计算结果表明，MCo(CN)中NTE的低频声子振动模式与M-N键特征有更强的关系。本工作揭示了相关键在NTE开放框架材料中的重要作用。
