高岭石电子结构的密度泛函理论研究

Density functional theory study on the electronic structure of kaolinite

在软岩隧道工程中经常遇到的巷道大变形问题,主要是由于高岭石、蒙脱石等粘土矿物吸水膨胀所引起.为了解决这些工程安全问题,从微观的角度对高岭石的物理、化学性质进行密度泛函理论研究.研究发现:高岭石具有较大的间接带隙,带隙宽度值为4.89 e V;高岭石的导带底(CBM)和价带顶(VBM)分别位于Γ点和B点;高岭石的金属阳离子和氧阴离子之间形成的化学键主要是离子键,并含有少量的共价键成分;高岭石的VBM和CBM分别由氧2P态和金属阳离子态组成.

In soft-rock tunnel engineering, the large deformation of roadway which is caused by the expansion of the clay minerals such as kaolinite and montmorillonite is often encountered. To deal with these engineering safe problems, the physical and chemical properties of kaolinite should be studied by using density-functional theory. It is found that kaolinite has a large indirect band gap and the band gap width is 4.89 e V; kaolinite has the conduction band minimum(CBM) and valence band maximum(VBM) being at the Γ and B points, respectively. The chemical bonding between cations and oxygen anions in kaolinite is mainly ionic, accompanied as well by a minor covalent component. It is pointed out the VBM and CBM of kaolinite consists of oxygen 2p and cations states, respectively.