| Autor: |
Tao-Tao Shi, Jie Zheng, Lin Shao, Xiong-Ze Pan, Bi-Yu Tang |
| Rok vydání: |
2015 |
| Předmět: |
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| Zdroj: |
Intermetallics. 65:29-34 |
| ISSN: |
0966-9795 |
| DOI: |
10.1016/j.intermet.2015.05.010 |
| Popis: |
The native point defects in C14 Mg 2 Ca Laves phase are studied from the first-principles density functional theory calculations within GGA approximation. The defect formation energies indicate that anti-site defects are energetically favored over vacancies. Under Mg-rich and even general Ca-rich condition, defect Mg Ca of Mg anti-site on Ca sublattice is favorable owing to the lowest formation energy. The Ca Mg2 defect of Ca anti-site on Mg2 sublattice is also likely dominant only under extreme Ca-rich environment. The present results could explain reasonably the asymmetric off-stoichiometry of Mg 2 Ca. The effective point defect concentrations of Mg 2 Ca as a function of composition and temperature at experimental range are also calculated from a canonical statistical model, and the derived results show a linear relationship between the logarithm of defect concentration and T −1 . Geometrical factor is further studied, and it is found that atomic size possesses an obvious influence on the structure of point defect in Mg 2 Ca. The electronic feature is further studied to reveal underlying mechanism for formation of point defects. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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