Structural Prediction and Overall Performances of CrSi<sub>2</sub> Disilicides: DFT Investigations
Yong Pan
Abstract
Chromium-based silicides (Cr–Si) are broadly used in thermoelectric devices, semiconductors, ultrahigh-temperature devices, and energy-storage systems. However, the structural feature and related properties of CrSi2 are not clear. Here, the structural, mechanical, and physical performances of CrSi2 were studied from density functional theory investigations. Four phases: C40 (hexagonal)-CrSi2, C11b (tetragonal)-CrSi2, C49 (orthorhombic)-CrSi2, and C54 (orthorhombic)-CrSi2 are considered. In this work, two novel structures: C49 (orthorhombic)-CrSi2 and C54 (orthorhombic)-CrSi2 are first predicted. Especially, CrSi2 with C11b (tetragonal) has better stability compared to other CrSi2. Here, CrSi2 with the C11b (tetragonal) phase shows the strongest elastic modulus among all CrSi2. However, the Vickers hardness of CrSi2 with the C49 (orthorhombic) phase is 34.9 GPa. Furthermore, the band gap of CrSi2 with the C40 (hexagonal) phase and the C54 (orthorhombic) phase is 0.392 and 0.040 eV, respectively, indicating that they are semiconductor materials. Finally, the ultrahigh-temperature thermodynamic properties of CrSi2 disilicides are determined from the lattice vibrations of Si and Si–Cr bonds.