| GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS |
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Theoretical Studies on Defects of Kaolinite in Clays |
| HE Man-Chao1, FANG Zhi-Jie1, ZHANG Ping2 |
| 1State Key Laboratory of Deep Geomechanics and Underground Engineering, China University of Mining and Technology, Beijing 1000832Institute of Applied Physics and Computational Mathematics, Beijing 100088 |
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| Cite this article: |
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HE Man-Chao, FANG Zhi-Jie, ZHANG Ping 2009 Chin. Phys. Lett. 26 059101 |
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Abstract Using the first-principles methods, we study the formation energetics and charge doping properties of the extrinsic substitutional defects in kaolinite. Especially, we choose Be, Mg, Ca, Fe, Cr, Mn, Cu, Zn as extrinsic defects to substitute for Al atoms. By systematically calculating the impurity formation energies and transition energy levels, we find that all group-II defects introduce the relative shallow transition energy levels in kaolinite. Among them, MgAl has the shallowest transition energy level at 0.08eV above the valence band maximum. The transition-elemental defects FeAl, CrAl, and MnAl are found to have relative low formation energies, suggesting their easy formation in kaolinite under natural surrounding conditions. Our calculations show that the defects CuAl and ZnAl have the high formation energies and deep transition energy levels, which exclude the possibility of their formation in natural kaolinite.
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| Keywords:
91.60.Ed
71.55.-i
91.60.-x
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Received: 26 December 2008
Published: 23 April 2009
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| PACS: |
91.60.Ed
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(Crystal structure and defects, microstructure)
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71.55.-i
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(Impurity and defect levels)
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91.60.-x
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(Physical properties of rocks and minerals)
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