The structural parameters, the formation energies, and the elastic and thermodynamic properties of the （CuxNi1-x）3Sn phase with different structures are studied by the virtual crystal approximation （VCA） and super...The structural parameters, the formation energies, and the elastic and thermodynamic properties of the （CuxNi1-x）3Sn phase with different structures are studied by the virtual crystal approximation （VCA） and super-cell （SC） methods. The lattice constants, formation energies, and elastic constants obtained by SC and VCA are generally consistent with each other. It can be inferred that ttle VCA method is suitable for （CuxNil ,）3Sn ordered phase calculation. The calculated results show that the equilibrium structures of Cu3Sn and Ni3Sn are D0a and D019 respectively. （CuxNi1-x）3Sn D03 with various components are the mctastable phase at temperature of 0 K, just as D022 and L I2. With the temperature increase, tile free energy of the D03 is lower than those of D022 and L12, and D022 and L12 eventually turn into D03 in tile aging process. The （CuxNi1-x）3Sn D022 is first precipitated in a solid solution because its structure and cell volume are most similar to Ihose of a solid solution matrix. The LI2 and the D022 possess better mechanical stability than the D03. Also, they may play a more important role in the strengthening of Cu-Ni-Sn alloys. This study is valuable lk）r further research on Cu-Ni-Sn alloys.展开更多
Based on k · p analysis and realistic tight-binding calculations, we find that time-reversal-breaking Weyl semimetals can be realized in magnetically-doped(Mn, Eu, Cr, etc.) Sn_(1-x)Pb_x(Te, Se) class of topologi...Based on k · p analysis and realistic tight-binding calculations, we find that time-reversal-breaking Weyl semimetals can be realized in magnetically-doped(Mn, Eu, Cr, etc.) Sn_(1-x)Pb_x(Te, Se) class of topological crystalline insulators. All the Weyl points are well separated in momentum space and possess nearly the same energy due to high crystalline symmetry.Moreover, both the Weyl points and Fermi arcs are highly tunable by varying Pb/Sn composition, pressure, magnetization,temperature, surface potential, etc., opening up the possibility of manipulating Weyl points and rewiring the Fermi arcs.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0301402)the Project of Innovation-Driven Plan in Central South Universitythe State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China
文摘The structural parameters, the formation energies, and the elastic and thermodynamic properties of the （CuxNi1-x）3Sn phase with different structures are studied by the virtual crystal approximation （VCA） and super-cell （SC） methods. The lattice constants, formation energies, and elastic constants obtained by SC and VCA are generally consistent with each other. It can be inferred that ttle VCA method is suitable for （CuxNil ,）3Sn ordered phase calculation. The calculated results show that the equilibrium structures of Cu3Sn and Ni3Sn are D0a and D019 respectively. （CuxNi1-x）3Sn D03 with various components are the mctastable phase at temperature of 0 K, just as D022 and L I2. With the temperature increase, tile free energy of the D03 is lower than those of D022 and L12, and D022 and L12 eventually turn into D03 in tile aging process. The （CuxNi1-x）3Sn D022 is first precipitated in a solid solution because its structure and cell volume are most similar to Ihose of a solid solution matrix. The LI2 and the D022 possess better mechanical stability than the D03. Also, they may play a more important role in the strengthening of Cu-Ni-Sn alloys. This study is valuable lk）r further research on Cu-Ni-Sn alloys.
基金Project supported by the MRSEC Program of the National Natural Science Foundation of China(Grant No.DMR-1419807)the Start Up Funding from HKUST and the National Thousand-Yong-Talents Program of China
文摘Based on k · p analysis and realistic tight-binding calculations, we find that time-reversal-breaking Weyl semimetals can be realized in magnetically-doped(Mn, Eu, Cr, etc.) Sn_(1-x)Pb_x(Te, Se) class of topological crystalline insulators. All the Weyl points are well separated in momentum space and possess nearly the same energy due to high crystalline symmetry.Moreover, both the Weyl points and Fermi arcs are highly tunable by varying Pb/Sn composition, pressure, magnetization,temperature, surface potential, etc., opening up the possibility of manipulating Weyl points and rewiring the Fermi arcs.
