ZnS类石墨烯热膨胀系数、弹性模量以及有效电荷变化规律研究

考虑到形变和原子的非简谐振动,用固体物理方法,研究了ZnS类石墨烯的热膨胀系数和弹性模量随温度的变化规律以及有效电荷和极性与形变的关系,探讨了形变和原子非简谐振动对它们的影响.结果表明:①ZnS类石墨烯的热膨胀系数为负值,数值在1.178×10~(-3)～22.323×10~(-3)K~(-1)之间随着温度升高而增大;而弹性模量在0.241 405～453.253 5 GPa之间随着温度的升高而增大.②简谐近似下,热膨胀系数为零,弹性模量为常量;考虑非简谐项后它们才随温度升高而变化,温度愈高,非简谐效应愈显著.③大小形变、剪切形变、单轴形变这3种形变中,大小形变对正有效电荷、单轴形变对负有效电荷影响最大,剪切形变对正、负有效电荷影响最小;④大小形变对极性的影响可达到70.4%,而剪切形变的影响仅为46.5%.

On Thermal Expansion and Elastic Modulus and Effective Charge of ZnS Graphene

Considering the deformation and the anharmonic vibration of the atoms, we have studied the temperature-dependence of the thermal expansion coefficient and the elastic modulus of ZnS graphene, the relationship between the effective charge and the polarity and the deformation by the solid physical method. We have discussed the effects of the deformation and the atomic anharmonic vibration on them. The results show that the thermal expansion coefficient of ZnS graphene is negative, and the value is between1.1781.178×10^-3K^-1 and 22.323×10^-3, which is increasing with temperature. The value of elastic modulus is between 0.241 405-453.253 5 GPa increasing with temperature. In the consideration of the simple harmonic approximation, the thermal expansion coefficient is zero and the elastic modulus are constant. When the anharmonic term is considered, the thermal expansion coefficient and the modulus of elasticity vary with the temperature. The higher the temperature is, the more obvious the anharmonic effect is. Among the deformation shear, the shear deformation and uniaxial deformation, the size deformation has the greatest influence on the positive effective charge, the uniaxial deformation has the greatest influence on the negative effective charge, and the shear deformation has the least influence on the positive and negative effective charge. The influence of size deformation on polarity can reach 70.4%, while the effect of shear deformation is only 46.5%.