First-principles calculations on adsorption-diffusion behavior of Boron atom with tungsten surface

Abstract

In this work, adsorption-diffusion behavior of Boron atom along and into W surface as well as the basic Boron atom absorption-diffusion behavior in W bulk were studied using first-principles density functional theory and climbing image nudged elastic band (CI-NEB) method. The result indicates that the octahedral interstice is the most stable position for B atom absorption and the energy barrier for B atom diffusing between two neighboring octahedral interstices in W bulk is 2.476 eV. For the adsorption behavior of Boron atom on W surface, Hollow site is the most stable adsorption position for W (100) surface and W (110) surface, while Hollow-II Site is the most stable adsorption position for W (111) surface. When B atom diffusing along W surface, the energy barrier for B atom diffusing along W (100) surface is the largest followed by W (110) surface and W (111) surface. During B atom diffusion into W surface, the needed energies for B atom diffusing into W (100) surface, W (110) surface and W (111) surface are 2.231 eV, 1.87 eV and 1.63 eV, respectively. After B atom diffuses to the 3rd, 3rd and 4th atomic layer below W (100) surface, W (110) surface and W (111) surface, the subsequent diffusion behavior shows the bulk diffusion characteristic. Beside, atomic diffusion coefficient D indicates that no matter diffusing along or into W surface, W (111) surface provides the best diffusion condition.