石墨烯和石墨炔的温度依赖弹性常数和极限强度
Temperature dependent elastic constants and ultimate strength of graphene and graphyne
摘要：
本文基于第一性原理计算结合准谐波近似，重点分析了石墨烯和石墨烯炔的晶格结构、热膨胀系数、弹性常数和极限强度随温度的变化规律.对于线性热膨胀系数，石墨烯和石墨炔两者在低温区域中显示负区域。该系数在高温下增加到正值。石墨烯具有优异的机械性能，杨氏模量E11=371.0 N/m，E22=378.2 N/m，室温下的极限拉伸强度为119.2 GPa。基于我们的分析，发现石墨烯的机械性能对高达1200 K的温度升高具有很强的抵抗力。石墨烯还显示出良好的机械性能，在室温下杨氏模量E11=224.7 N/m，E22=223.9 N/m和极限拉伸强度为81.2 GPa，但是石墨烯的机械性能相对于温度的增加具有比石墨烯更弱的抵抗力。
英文摘要：
Based on the first principles calculation combined with quasi-harmonic approximation, in this work we focus on the analysis of temperature dependent lattice geometries, thermal expansion coefficients, elastic constants and ultimate strength of graphene and graphyne. For the linear thermal expansion coefficient, both graphene and graphyne show a negative region in the low temperature regime. This coefficient increases up to be positive at high temperatures. Graphene has superior mechanical properties, with Young modulus E11=371.0 N/m, E22=378.2 N/m and ultimate tensile strength of 119.2 GPa at room temperature. Based on our analysis, it is found that graphene's mechanical properties have strong resistance against temperature increase up to 1200 K. Graphyne also shows good mechanical properties, with Young modulus E11=224.7 N/m, E22=223.9 N/m and ultimate tensile strength of 81.2 GPa at room temperature, but graphyne's mechanical properties have a weaker resistance with respect to the increase of temperature than that of graphene.
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