A Tour of Soft Atomic Motions: Chemical Pressure Quadrupoles Across Transition Metal–Main Group 1:2 Structure Types
A Tour of Soft Atomic Motions: Chemical Pressure Quadrupoles Across Transition Metal–Main Group 1:2 Structure Types
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DOI：
10.1021/acs.chemmater.2c02410
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发表时间：
2022-11
影响因子：
8.6
通讯作者：
Kendall R Kamp;D. Fredrickson
中科院分区：
文献类型：
--
作者：
Kendall R Kamp;D. Fredrickson
材料的合理设计需要理解结构和性能之间的关系。在某些领域，计算工具和建模的进步已经描绘出了许多这些联系。然而，在金属间化合物领域，仍然需要这种关系的原理。最近，我们说明了DFT-化学压力（CP）分析如何将晶体排列中的几何图案与金属间化合物的声子能带结构联系起来，从而与振动和原子运动相关的物理特性联系起来。这里的关键指标是四极CP特征--正负原子间压力相互垂直的分布。然后，这些四极子为原子创造了低能量的运动路径，这些路径可以与各种结构现象联系起来，例如各向异性振动和无公度调制。在这篇文章中，我们调查的CP四极子的存在下，在收集的TE 2结构（T =过渡金属和E =主族元素）和他们所扮演的角色，观察到这些化合物的行为。我们开始通过开发CP四极特征的度量，其可以从CP分析的输出计算。在对17种TE_2结构类型进行了比较之后，我们进一步研究了四种具有四极特征的体系：（1）Co-Sn二元体系，其中CuAl_2型CoSn_2中Co原子上的四极子决定了CoSn_3中超结构的特征;（2）毒砂型CoSb 2，其中Sb原子上的高四极CP分布与其高温白铁矿相变过程中的运动相关-类型形式;（3）CrSi 2结构，其中晶格的膨胀被预测为打开潜在软运动的螺旋路径，类似于Nowotny Chimney Ladder系列的潜在软运动;以及（4）CdAs 2类型，其CP特征预期能够将Li原子作为客人。总之，这些案例研究突出了潜在的CP四极链接本地原子的安排与各种新兴的金属间化合物相的属性。
The rational design of materials requires an understanding of the relationships between structure and properties. In some fields, advances in computational tools and modeling have mapped out many of these connections. In the realm of intermetallics, however, principles for such relationships are still needed. Recently, we illustrated how the DFT–Chemical Pressure (CP) analysis can link geometrical motifs within crystalline arrangements to the phonon band structures of intermetallics and thus the physical properties related to vibrations and atomic motion. The key indicators here are quadrupolar CP features─distributions in which positive and negative interatomic pressures are oriented perpendicular to one another. These quadrupoles then create low energy paths of motion for the atoms that can be linked to various structural phenomena, such as anisotropic vibrations and incommensurate modulations. In this article, we survey the presence of CP quadrupoles in a collection of TE2structures (T = transition metal and E = main group element) and the roles they play in the behavior observed for these compounds. We begin by developing a metric for CP quadrupolar character, which can be calculated from the output of CP analysis. After compiling these metrics for 17 TE2structure types, we delve deeper into four systems detected as exhibiting atomic sites with quadrupolar character: (1) the Co–Sn binary system, where the quadrupoles on the Co atoms in CuAl2-type CoSn2direct the features of its superstructure in CoSn3; (2) arsenopyrite-type CoSb2, in which the highly quadrupolar CP distributions on the Sb atoms correlate with the motions followed during the phase transition to its high-temperature marcasite-type form; (3) the CrSi2structure, in which the expansion of the lattice is predicted to open a helical path of potential soft motion analogous to that underlying the Nowotny Chimney Ladder series; and (4) the CdAs2type, whose CP features anticipate the ability to incorporate Li atoms as guests. Together, these case studies highlight the potential for CP quadrupoles to link local atomic arrangements with a variety of emergent properties in intermetallic phases.