Temperature-Dependent Mechanical and Electronic Properties of 3C-SiC: Insights From First-Principles Calculations

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The zinc-blende polytype of silicon carbide, known as 3C-SiC, is a promising ceramic material in high-temperature energy applications. However, the reported data on its mechanical and electronic properties, especially at elevated temperatures, are either lacking or scarce, with sizeable uncertainty. In this study, we present a comprehensive study on the temperature-dependent mechanical and electronic properties of 3C-SiC. First-principles calculations are combined with the quasi-harmonic approximation to investigate lattice properties at elevated temperature. We find that phonons dominate the temperature-dependent behavior. As temperature increases, all elastic constants exhibit a softening trend, and 3C-SiC becomes more elastically anisotropic. Our calculated degree of softening of elasticity is weaker than the values reported by previous studies. Moreover, the effects of thermal expansion and electron–phonon coupling on the electron band energy at elevated temperatures are investigated. The electron–phonon coupling dominates the temperature dependence of the band gap, where 3C-SiC maintains its wide gap at high temperature.