Caracterização tecnológica de minerais lamelares para obtenção de materiais bidimensionais

• Autor(a) principal: Souza, Leonardo Antônio Custódio
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do Mackenzie
• Texto Completo: http://dspace.mackenzie.br/handle/10899/26437
• topic: materiais bidimensionais; minerais; estrutura cristalina; CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA

Graphene was the precursor two-dimensional (2D) material for the development of 2D nanomaterials. Such an advent revealed the exceptional optical, physical, electrical and thermal properties of this innovative material. The scientific community around the world, aware of this fact, has envisioned the development of new applications and technologies in various branches of science. Driven by the discovery of graphene, several studies have shown that other types of 2D materials can also have excellent properties, whether similar, complementary or antagonistic to graphene. The purpose of this research was the search for specimens of natural chemicals (minerals), with potential to be delaminated in order to obtain 2D materials. By observing the crystalline structures and cleavages, it was possible to select and classify fifty-six specimens according to their potential for exfoliation and obtaining twodimensional materials. From the indicated minerals, three samples were obtained and then characterized by: optical microscopy; atomic force microscopy and scanning electron microscopy; Raman and microwave probe spectroscopy. Optical microscopy and scanning electronics indicated that the minerals were exfoliated according to their cleavage plans. The exfoliated particles exhibited an average thickness of 2nm, a fact certified by atomic force microscopy. Information obtained by Raman spectroscopy shows that there was a significant change in the crystalline structure of clinochlore and teluronevskite by exfoliation, presenting very distinct spectra between the primitive and the exfoliated sample. Kermesite showed a good correspondence between these two spectra indicating an exfoliation where the chemical composition was maintained. Data obtained through the probe indicated the actual chemical composition of the samples. Higher iron content indicated that the specimen allegedly indicated as clinochlore is in fact a specimen of chamosite. Among the three minerals studied, kermesite presented the best results, enabling further studies for this specimen. The use of the International Mineralogical Association (IMA) database has proved to be a useful source for selecting specimens with layered crystal structure. Heterostructures and cleavage of minerals have shown to be facilitating attributes for exfoliation and obtaining two-dimensional structures.