Effect of high hydrostatic pressure on structural stability of Ti3GeC2: A first-principles investigation

An investigation into the structural stability, electronic and elastic properties of Ti3GeC2 under high hydrostatic pressure was conducted using first-principles calculations based on density functional theory (DFT). From the energy and enthalpy calculations, and the variations of elastic constants with pressure, we conclude that α‐Ti3GeC2α‐Ti3GeC2 is most stable upon compression to 100 GPa, which is not consistent with the nonhydrostatic in situ synchrotron X-ray diffraction studies. The higher structural stability was analyzed in terms of electronic level. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of all polymorphs of Ti3GeC2.

The less phase stability of β‐Ti3β‐Ti3 SiC2 compared to that of α‐Ti3α‐Ti3 SiC2 can be interpreted by the states between −6.0 and 3.6 eV shift toward the higher energy region for β‐Ti3β‐Ti3 SiC2Figure optionsDownload as PowerPoint slideResearch highlights
► From the energy and enthalpy calculations of polymorphs for Ti3GeC2, we can conclude that Ti3GeC2 possessed higher stable structural stability under pressure to 100 GPa, which is not consistent with the nonhydrostatic experiments.
► The higher stable structure of Ti3GeC2 is testified by the calculated variations of elastic constants with pressure.
► The reasons for this higher stable phase stability were discussed in terms of the electronic level.