The site preferences, fast and huge anisotropic diffusion mechanisms of Cu （Ag） in β-Sn as well as their reduction on the self-diffusivity of Sn, have been investigated using the first-principles and ab initio mole...The site preferences, fast and huge anisotropic diffusion mechanisms of Cu （Ag） in β-Sn as well as their reduction on the self-diffusivity of Sn, have been investigated using the first-principles and ab initio molecular dynamics methods. We have found that Cu prefers the interstitial site, whereas Ag is preferable in the substitutional site, which is mostly dominated by their different size factors. Electronic structure further evidences that the d-s hybridization between the solute and the host atom also contributes to the site preferences. It is also deduced that the fast diffusion of Cu （Ag） is mostly due to the interstitial diffusion mechanism and their diffusivity can be correlated with the amount of their respective interstitial solution. Their faster diffusion along the c-axis can be attributed to the extremely low migration energy barrier caused by the straight tunnel of considerable size with the screw axis symmetry of 2π/4 along the c-axis. Furthermore, it is found that during the process of diffusion the interstitially dissolved Cu （Ag） atoms would combine with the nearby Sn-vacancy and further annihilate the vacancy, thereby reducin~ the self-diffusion of Sn.展开更多
基金supported by the ‘Hundred Talents Project’ of the Chinese Academy of Sciences and from the Major Research Plan (Grant No. 91226204)the Key Research Program of Chinese Academy of Sciences (Grant No. KGZD-EW-T06)+2 种基金the National Natural Science Foundation of China (Grant Nos. 51474202 and 51174188)the Beijing Supercomputing Center of CAS (including its Shenyang branch)the high-performance computational cluster in the Shenyang National University Science and Technology Park
文摘The site preferences, fast and huge anisotropic diffusion mechanisms of Cu （Ag） in β-Sn as well as their reduction on the self-diffusivity of Sn, have been investigated using the first-principles and ab initio molecular dynamics methods. We have found that Cu prefers the interstitial site, whereas Ag is preferable in the substitutional site, which is mostly dominated by their different size factors. Electronic structure further evidences that the d-s hybridization between the solute and the host atom also contributes to the site preferences. It is also deduced that the fast diffusion of Cu （Ag） is mostly due to the interstitial diffusion mechanism and their diffusivity can be correlated with the amount of their respective interstitial solution. Their faster diffusion along the c-axis can be attributed to the extremely low migration energy barrier caused by the straight tunnel of considerable size with the screw axis symmetry of 2π/4 along the c-axis. Furthermore, it is found that during the process of diffusion the interstitially dissolved Cu （Ag） atoms would combine with the nearby Sn-vacancy and further annihilate the vacancy, thereby reducin~ the self-diffusion of Sn.
