MXenes are an emerging family of two-dimensional (2D) materials with highly tunable properties. Their fundamental mechanical properties have received comparatively less research attention than other functional properties due to the difficulty of performing such experiments on 2D materials. Therefore, we have developed a bond-order potential for surface-terminated titanium carbide MXene monolayers $({\mathrm{Ti}}_{n+1}{\mathrm{C}}_n{T}_x, n=1,2,\text{or}3,T=\text{−}\mathrm{O}\text{or}\text{−}\mathrm{F})$, enabling large-scale atomistic simulations which can probe both mechanical properties and deformation mechanisms. The bond-order potential does an excellent job of capturing relevant structural, elastic, and defect properties of the studied MXenes with and without surface terminations and is computationally scalable to allow for molecular dynamics simulations of monolayers hundreds of nanometers in size, only an order of magnitude below typical monolayer experiments. Crucially, these large-scale simulations open the possibility to study more realistic MXenes containing distributions of both defects and nonuniform surface terminations. We demonstrate in this work that these variables can have significant effects on the mechanical response of MXenes and therefore offer additional property-tuning capabilities which can be utilized to inform synthesis and postprocessing techniques.

中文翻译：

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表面封端碳化钛 MXene 单层的键序电位Tin+1CnTx(n=1,2,or3;T=-Oor-F)

MXenes 是一个新兴的二维 (2D) 材料家族，具有高度可调的特性。由于难以在二维材料上进行此类实验，它们的基本机械性能比其他功能性能受到的研究关注相对较少。因此，我们开发了表面封端碳化钛 MXene 单层的键序势$({钛}_{n+1}{\mathrm{C}}_n{吨}_X, n=1,2,\text{或者}3,吨=\text{-}\mathrm{○}\text{或者}\text{-}\mathrm{F})$，实现可以探测机械性能和变形机制的大规模原子模拟。键序势能很好地捕获研究的 MXene 的相关结构、弹性和缺陷特性，无论有无表面终端，并且在计算上具有可扩展性，以允许对数百纳米大小的单层进行分子动力学模拟，仅一个数量级幅度低于典型的单层实验。至关重要的是，这些大规模模拟为研究包含缺陷和不均匀表面终止分布的更真实的 MXene 提供了可能性。