Li Hengtao, Wang Hongyan, Li Xiumei, Li Yong, Chen Yuanzheng, Wang Hui
School of Physical Science and Technology, Key Laboratory of Advanced Technology of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
Superconductivity and New Energy R&D Center, Key Laboratory of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu, Sichuan 610031, People's Republic of China.
J Phys Condens Matter. 2022 Sep 21;34(46). doi: 10.1088/1361-648X/ac9170.
Transition metal carbides and nitrides (MXenes) are considered the new generation of flexible electronic materials because of their superior mechanical strength and flexibility. Based on the density functional theory, the structures, electronic properties and mechanical properties of the 2D Zr-based MXenes with and without surface functional groups (O, F and OH) are investigated systematically to explore their elastic properties and tensile fracture mechanism. The results reveal the tensile strength and critical strain under biaxial tensile direction can reach 52 GPa, 12% for ZrC and 55 GPa, 19% for ZrC, more outstanding than the mechanical behavior of the pristine TiC (47 GPa, 9.5%). The tensile behaviors of the functionalized ZrCT(= 1, 2, T = O, F, OH) strongly depend on the crystallographic orientation and the surface functional group. The phonon spectrum under the critical strain indicates the tensile fracture of the pristine Zr-based MXenes was determined by phonon instability, except along the armchair direction of ZrC and zigzag direction of ZrC. During tensile strain, the collapse of ZrCFand ZrC(OH)(= 1, 2) are mainly caused by internal Zr-C bond rupture and transfer to the surface. While the O-functionalized ZrCO(= 1, 2) presented the opposite collapse trend. Additionally, according to the research results of critical strain, elastic modulus and electrical conductivity, F/OH-terminated ZrC MXene is relatively more suitable for flexible sensors of wearable devices than ZrCT.
过渡金属碳化物和氮化物（MXenes）因其优异的机械强度和柔韧性而被视为新一代柔性电子材料。基于密度泛函理论，系统研究了有无表面官能团（O、F和OH）的二维Zr基MXenes的结构、电子性质和机械性质，以探索其弹性性质和拉伸断裂机制。结果表明，在双轴拉伸方向下，ZrC的拉伸强度和临界应变可分别达到52 GPa、12%，ZrC的拉伸强度和临界应变可分别达到55 GPa、19%，比原始TiC（47 GPa、9.5%）的力学性能更优异。功能化ZrCT（T = O、F、OH，T = 1、2）的拉伸行为强烈依赖于晶体取向和表面官能团。临界应变下的声子谱表明，除了沿着ZrC的扶手椅方向和ZrC的锯齿方向外，原始Zr基MXenes的拉伸断裂由声子不稳定性决定。在拉伸应变过程中，ZrCF和ZrC(OH)（T = 1、2）的崩塌主要是由内部Zr-C键的断裂并转移到表面引起的。而O官能化的ZrCO（T = 1、2）则呈现出相反的崩塌趋势。此外，根据临界应变、弹性模量和电导率的研究结果，F/OH端接的ZrC MXene相对于ZrCT而言，相对更适合用于可穿戴设备的柔性传感器。
