DFT study of structural, mechanical, and thermodynamic properties of Mg2C3 crystals under varying pressures: Phase transitions and material behavior

Abstract

This paper offers a comprehensive DFT investigation into the structural, mechanical and thermodynamic characteristics of four distinct Mg2C3 crystal structures across a broad pressure spectrum spanning from 0[Formula: see text]GPa to 100[Formula: see text]GPa, utilizing the GGA-PBE method. Our rigorous calculations indicate that Mg2C3 undergoes phase transitions from the Pnnm phase to the [Formula: see text] phase at P[Formula: see text][Formula: see text]GPa, and subsequently to the [Formula: see text] phase at [Formula: see text][Formula: see text]GPa. Notably, within the pressure range of approximately 0–20[Formula: see text]GPa, the enthalpy difference between the Pnnm and Pbca phases shrinks considerably, hinting at the possibility of their coexistence under lower pressure conditions. Furthermore, our analysis delves into the interplay between the mechanical and thermodynamic properties of Mg2C3 and pressure, revealing that the [Formula: see text] structure possesses exceptional ductility in Mg2C3 crystals under low to moderate pressure, whereas Mg2C3 exhibits brittleness under high pressure. Additionally, a notable variation in material hardness is observed throughout the phase transition process.