Quantitative evaluation of effects of isomorphic substitutions on delamination energies of clay minerals

The clay minerals with layered structures are strong adsorbents of cations in the environment. The surfaces and interlayers of the clay minerals are primary adsorption sites, i.e., the layered structure is the origin of the strong adsorption. The strength of the attraction between the layers of the clay minerals is significant for the adsorption. However, the effects of the microscopic structure of the clay minerals on the strength of the attraction were understood poorly. To find the effects, we evaluated the cleavage energies to delaminate muscovite sheets with several isomorphic substitution patterns by first-principles calculations. As a result, the substitution pattern changes the delamination energy up to 86%. This result suggested that the effects of the isomorphic substitution gives significant effect on the attraction between the layers of muscovite. (author)