DFT insights into the electronic structure, mechanical behaviour, lattice dynamics and defect processes in the first Sc-based MAX phase Sc2SnC

doi:10.21203/rs.3.rs-870934/v1

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Research Article

DFT insights into the electronic structure, mechanical behaviour, lattice dynamics and defect processes in the first Sc-based MAX phase Sc₂SnC

https://doi.org/10.21203/rs.3.rs-870934/v1

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The ceramic and metallic properties of the MAX phases make them attractive for numerous technological applications. The very recent experimental synthesis of the first scandium (Sc) based MAX phase Sc₂SnC is an important addition to the MAX phase family as it further expands the diversity of physical characteristics of this family. Here we employ density functional theory (DFT) calculations to investigate the structural, electronic, mechanical, lattice dynamical properties of Sc₂SnC including defect processes to compare with those of existing M₂SnC phases. The calculated structural properties are in good agreement with the experimental values. The new phase Sc₂SnC is structurally, mechanically and dynamically stable. Sc₂SnC is metallic with a mixture of covalent and ionic character. The covalency of Sc₂SnC including M₂SnC is mostly controlled by the effective valence. Sc₂SnC in M₂SnC family ranks second in the scale of deformability, softness and machinability. The elastic anisotropy level in Sc₂SnC is moderate compared to the other M₂SnC phases. Like other members of the M₂SnC family, Sc₂SnC has the potential to be etched into 2D MXenes and has the potential to be a thermal barrier coating (TBC) material. The hardness and melting point of Sc₂SnC, including M₂SnC, follows the trend of bulk modulus.