,Theoretical Studies on Defects of Kaolinite in Clays

• 作 者: HE Man-Chao FANG Zhi-Jie ZHANG Ping
• 机 构: State Key Laboratory of Deep Geemechanics and Underground Engineering, China University of Mining an
• 出 处: 中国物理快报（英文版）
• 发表日期: 2009年5期

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 AI 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, MgAI has the shallowest transition energy leve! at 0.08 eV above the valence band maximum. The transitionelemental defects ReAl, 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.