First-Principles Studies on Properties of Boron-Related Impurities in c-BN |
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Authors: | TIAN Fu-Bo WANG Xiao-Li MA Yan-Ming CUI Tian LIU Bing-Bing ZOU Guang-Tian |
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Affiliation: | State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 |
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Abstract: | We investigate, by first-principles calculations, the pressure dependence of formation enthalpies and defective geometry and bulk modulus of boron-related impurities (VB, CB, NB, and OB) with different charged states in cubic boron nitride (c-BN) using a supercell approach. It is found that the nitrogen atoms surrounding the defect relax inward in the case of CB, while the nitrogen atoms relax outward in the other cases. These boron-related impurities become much more stable and have larger concentration with increasing pressure. The impurity CB+1 is found to have the lowest formation enthalpy, make the material exhibit semiconductor characters and have the bulk modulus higher than ideal c-BN and than those in the cases of other impurities. Our results suggest that the hardness of c-BN may be strengthened when a carbon atom substitutes at a B site. |
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Keywords: | 71.15.Mb 61.72.-y 71.15.Nc |
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