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Investigating the phase transition and properties of CaSiN2 under pressure based on first-principles calculations
Author(s)
Meethan, Weerachon
Kongnok, Thanundon
Fongkaew, Ittipon
Bootchanont, Atipong
Saisopa, Thanit
Meethan, Peeraya
Sailuam, Wutthigrai
Date Issued
December 1, 2023
Type
Article
Abstract
In this study, we apply first-principles calculations to examine the pressure-induced phase transformation of CaSiN2 in a range of pressure of 0–100 GPa. Its pressure-induced transitions at 1.3 GPa, 15.3 GPa, and 55.8 GPa followed the order of α- CaSiN2 → β- CaSiN2 → α- CaSiN2 → γ- CaSiN2, for α- CaSiN2 → β- CaSiN2, β- CaSiN2 → α- CaSiN2, and α- CaSiN2 → γ- CaSiN2, respectively. The stability of the phases of CaSiN2 was confirmed based on calculations of the Born criterion of elastic stability. Its behavior transitioned in the sequence of brittle (0–1.3 GPa) → ductile (1.3–55.8 GPa) → brittle (55.8–100 GPa). The structure of its projected orbital band reflected insulating behavior by CaSiN2 under a range of pressure of 0–55.8 GPa with a direct band gap, which transformed into metallic behavior by the γ- CaSiN2 phase under pressures higher than 55.8 GPa, due to a shift in energy to higher levels around the Γ point of the N p orbitals and Si p orbitals. The Si-N bonds in CaSiN2 were found to be covalent, while ionic bonding dominated the Ca-Si and Ca-N bonds in the range of pressure of 0–100 GPa. We also investigate and discuss its mechanical properties, Vickers hardness (Hv), average sound velocity vm, and Debye temperature (θD).
Citation
Journal of Physics and Chemistry of Solids, 183, 2023