Ab-initio investigations on elastic properties in L12 structure Al3Sc and Al3Y under high pressure

• The three-order polynomials of the dependencies of B and ΘD on the applied pressure are obtained.
• The anisotropic indexes of Al3Sc are larger than that of Al3Y and increases generally with the increasing P.
• The covalent-type bonding enhances in Al3Sc and Al3Y under applied pressures.

The effects of high pressure on elastic properties and electronic structures of L12 structure trialuminide Al3Sc and Al3Y compounds have been investigated by first-principles calculations within the local density approximation. The elastic properties and Debye temperature for Al3Sc and Al3Y increase with the increasing pressure, and the calculated values in elastic properties and Debye temperatures which obtained at 0 GPa are in good agreement with the available experiment data. The mechanical anisotropic properties are discussed using universal anisotropic index AU and Zener anisotropy index AZ. The calculated electronic properties suggest that a significant amount of charge in the interstitial region gives rise to an enhanced directional covalent-type bonding between the Sc (Y) and Al atoms as the pressure is up to 40 GPa.

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