KAOLINITE-SMECTITE · Crystal-chemistry and reaction paths of kaolinite-smectite mixed-layer clays

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Project objective

Mixed-layer clay minerals occur abundantly in soils and sediments, controlling their properties from mechanical stability to nutrient content. Recent discoveries in the field of mixed-layer clays, made by members of the host research group and the research group where I work, have opened new ways to study these minerals and revealed novel aspects. My project combines these two approaches in a detailed study of the mixed-layer mineral kaolinite-smectite. The main objectives of the project are 1) to fully characterize structurally and compositionally kaolinite-smectite, and 2) to use this information to assess the mechanism of smectite kaolinization. Natural kaolinite-smectite will be analysed using modern, complementary techniques, enhanced by tools of data analysis such as computer modelling.They include x-ray diffraction (composition, structure and particle size analysis), scanning electron microscopy (morphology of micro-crystals), high-resolution electron microscopy and microanalysis (chemical composition and structure of micro-crystals), thermal analysis, infrared spectroscopy (structure at atomic level). The evolution (composition, structure) along the kaolinite-smectite series will reveal the transformation mechanism. The results will contribute to a central problem in clay mineralogy, the nature of mixed-layering. Kaolinite-smectite is an ideal system for this study because it is composed of two members with great compositional and structural differences and will provide unambiguous results. Smectite kaolinization is a typical process of soil degradation and the understanding of its mechanism will help to assess soil degradation and soil sustainability, and to alter undesired trends. The project topic and techniques complement and deepen my previous experience, strengthening the chemical aspects of clay study in which I am planning to focus in the future. The project involves collaboration with a Spanish and an Italian group, providing further networking.

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Participants

• THE NATURAL HISTORY MUSEUM · LONDONCoordinatorUnited Kingdom

Links

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