The density functional calculations are performed to study the electronic structure and stability of Nb5SiB2 （001） surface with different terminations. The calculated cleavage energies along the （001） planes in Nb...The density functional calculations are performed to study the electronic structure and stability of Nb5SiB2 （001） surface with different terminations. The calculated cleavage energies along the （001） planes in Nb5SiB2 are 5.015 J · m-2 and 6.593 J· m-2 with the break of Nb=Si and Nb-NbB bonds, respectively. There exists a close correlation between the surface relaxation including surface ripple and the cleavage energy： the larger the cleavage energy, the larger the surface relaxation. Moreover, the surface stability of the NbsSiB2 （001） with different terminations has been investigated by the chemical potential phase diagram. From a thermodynamics point of view, the four terminations can be stabilized under different conditions. In chemical potential space, NbB （Nb） and Nb （Si） terminations are just stable in a small area, whereas Si （Nb） and Nb （NbB） terminations are stable in a large area （the letters in brackets represent the subsurface atoms）.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50771004)
文摘The density functional calculations are performed to study the electronic structure and stability of Nb5SiB2 （001） surface with different terminations. The calculated cleavage energies along the （001） planes in Nb5SiB2 are 5.015 J · m-2 and 6.593 J· m-2 with the break of Nb=Si and Nb-NbB bonds, respectively. There exists a close correlation between the surface relaxation including surface ripple and the cleavage energy： the larger the cleavage energy, the larger the surface relaxation. Moreover, the surface stability of the NbsSiB2 （001） with different terminations has been investigated by the chemical potential phase diagram. From a thermodynamics point of view, the four terminations can be stabilized under different conditions. In chemical potential space, NbB （Nb） and Nb （Si） terminations are just stable in a small area, whereas Si （Nb） and Nb （NbB） terminations are stable in a large area （the letters in brackets represent the subsurface atoms）.
