Structural, mechanical, thermal and electronic properties of novel ternary carbide Al4Si2C5 under high pressure by DFT calculation

Abstract

Structural, electronic, elastic and thermal properties of Al4Si2C5 under constant pressure were investigated by using first-principles theory. The total volume of the cell decreased by almost 15.7% under 40 GPa which is smaller than that of Al4SiC4 (16%), while the linear compressibility along [Formula: see text]- or [Formula: see text]-axis direction showed better anti-deformation behavior than that of along [Formula: see text]-axis direction. The peak heights of total density of state (TDOS) and partial density of state (PDOS) curves of Al4Si2C5 are slightly lowered with forced high pressure. Meanwhile, the mechanical properties of Al4Si2C5-like elastic constants and elastic moduli accelerate with the pressure increasing from 0 GPa to 40 GPa; the thermal expansion coefficient [Formula: see text] increases rapidly at lower temperature and this tendency gradually approaches a linear increase when the temperature is above 1000 K. At particular temperature, [Formula: see text] decreases continuously with the pressure accelerating. Heat capacity at constant volume ([Formula: see text] with pressure was also evaluated, the results displayed that [Formula: see text] is sensitive with the temperature rather than the pressure. The elastic anisotropy and Debye temperature with pressure were successfully obtained and discussed.