Effects of Deformation and Non - harmonic Vibration on Effective Charge, Thermal Expansion and Elastic Modulus of SiC

Abstract:

On the consideration of the deformation and atomic non-harmonic vibration, this paper applies the methods of Harrison bonding orbit and solid state physics to obtain thermal expansion coefficient and elastic modulus of hexagonal two-dimensional graphene compounds, and analytical formula of effective charge. Take SiC as an example, the paper discusses the effect of deformation and atomic non-harmonic vibration on SiC. The result shows that thermal expansion coefficient and elastic modulus of SiC enlarges slowly with increasing temperature, the thermal expansion coefficient and elastic modulus of SiC would be zero if not considering non-harmonic term, therefore, thermal expansion coefficient and elastic modulus enlarge with the increase of temperature is caused by non-harmonic effect. The deformation reduces the effective charge of SiC’s positive and negative ions by 14.5% and 8.56% respectively. The effect of deformation on positive ions is greater than negative ions. Among the deformations of size, shear, axial tensile and atomic vibrations, axial tensile deformation has the greatest effect on effective charge, while size deformation and shearing deformation has the smallest influence. When temperature increases, atomic non-harmonic vibration effect is presented more obvious, the deformation exerts greater influence on SiC polarity and effective charge.