通过逐平面剪切研究过渡金属二硼化物同素异形体转变的能量学
On energetics of allotrope transformations in transition-metal diborides via plane-by-plane shearing
AI总结：
本文利用第一性原理计算模拟IV–VII族过渡金属二硼化物沿α、γ、ω结构转变路径的逐平面滑动，揭示能量、结构、稳定性及力学指标趋势，发现MnB₂和MoB₂滑动势垒最低。
摘要：
过渡金属二硼化物以α型、γ型或ω型结构结晶，其中纯过渡金属层与纯硼层沿六方[0001]轴交替堆叠。本文将这些原型视为过渡金属平面的不同堆叠方式，并假设它们能够通过位移型转变从一种结构转变为另一种结构。我们采用第一性原理计算，模拟了IV–VII族过渡金属二硼化物中单个平面沿连接α、γ和ω结构的转变路径发生的滑动。研究依据沿转变路径的能量和结构变化，以及不同堆叠方式的力学稳定性和动力学稳定性，预测了与化学组成相关的趋势。结果表明，在所研究的TMB₂中，MnB₂和MoB₂具有总体最低的滑动势垒。此外，我们还讨论了由弹性常数导出的强度和延性指标的趋势，包括杨氏模量和Cauchy压力。
英文摘要：
Transition metal diborides crystallise in the $α$, $γ$, or $ω$ type structure, in which pure transition metal layers alternate with pure boron layers stacked along the hexagonal [0001] axis. Here we view the prototypes as different stackings of the transition metal planes and suppose they can transform from one into another by a displacive transformation. Employing first-principles calculations, we simulate sliding of individual planes in the group IV-VII transition metal diborides along a transformation pathway connecting the $α$, $γ$, and $ω$ structure. Chemistry-related trends are predicted in terms of energetic and structural changes along a transformation pathway, together with the mechanical and dynamical stability of the different stackings. Our results suggest that MnB$_2$ and MoB$_2$ possess the overall lowest sliding barriers among the investigated TMB$_2$s. Furthermore, we discuss trends in strength and ductility indicators, including Young's modulus or Cauchy pressure, derived from elastic constants.
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