Structural, mechanical, thermo-physical and electronic properties of η′-(CuNi)6Sn5 intermetallic compounds: First-principle calculations

• All η′-(CuNi)6Sn5 intermetallic compounds were researched.
• The influence of Ni atom doping position was considered and discussed.
• Structural, mechanical, thermo-physical and electronic properties were all investigated.
• Uneven distribution of Young's modulus at (001) planes is the main reason for anisotropy.
• Ni s and Ni p states can replace Cu s and Cu p states to hybridize with Sn s states at −7.98 eV.

First-principle calculations have been performed to investigate the structural, mechanical, thermo-physical and electronic properties of η′-(CuNi)6Sn5 intermetallic compounds. The results indicated that, the doped Ni atom can not only enhance the stability of the η′-Cu6Sn5, but also improve the mechanical and thermo-physical properties, which are more dependent on the Ni atom doping number than the doping position. In all the η′-(CuNi)6Sn5, Cu3Ni3Sn5 (Cu1+Cu3 site) shows the best stability, the most excellent deformation resistance and the highest hardness. The Cu6Sn5, Cu3Ni3Sn5, Cu4Ni2Sn5, Cu1Ni5Sn5 and Ni6Sn5 are ductile while the Cu5Ni1Sn5 and Cu4Ni2Sn5 are brittle. The anisotropies of η′-(CuNi)6Sn5 are all mainly due to the uneven distribution of Young's modulus at (001) planes, moreover, the anisotropy of Cu1Ni5Sn5 (Cu1+Cu2+Cu4 site) is the strongest while that of Ni6Sn5 is the weakest. The calculated Debye temperature and heat capacity showed that Cu4Ni2Sn5 (Cu2 site) possesses the best thermal conductivity (ΘD = 356.9 K) and Cu2Ni4Sn5 (Cu1+Cu2 site) possesses the largest heat capacity. From the electronic property analysis results, the Ni s and Ni p states can replace the Cu s and Cu p states to hybridize with Sn s states at −7.98 eV. Moreover, with the increasing number of the doped Ni atom, the hybridization between Cu d states at different positions is receded, while that between Ni d states is enhanced gradually.

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