Browsing by Author "Barcelos, Ingrid David"

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    Caracterização de sulfeto de antimônio bidimensional por microscopia de varredura por sonda.
    (2022) Benedito, Atália Júlio; Barboza, Ana Paula Moreira; Pinto, Elisângela Silva; Barboza, Ana Paula Moreira; Soares, Jaqueline dos Santos; Barcelos, Ingrid David
    Materiais em escala nanométrica apresentam diferentes propriedades se comparados às suas propriedades em escala macroscópica. Tais propriedades podem estar intercaladas entre aquelas associadas ao nível atômico (ou molecular). Logo, há um grande desenvolvimento de novos materiais nanoestruturados, não só na área de pesquisa acadêmica, como também, em setores que empregam alta tecnologia, na indústria eletrônica, aeroespacial e de embalagens, por exemplo. Uma linha de pesquisa que vem crescendo na área científica são os chamados materiais bidimensionais. A inspiração para a busca por novos materiais nessa dimensão se deve ao interesse na descoberta de propriedades capazes de modificar sistemas que conhecemos atualmente. Este projeto buscou investigar, pela primeira vez, um novo material bidimensional: o sulfeto de antimônio (Sb2S3) utilizando principalmente técnicas de Microscopia de Varredura por Sonda. O objetivo foi verificar desde os processos de obtenção do material, na escala nanométrica, até o estudo de suas propriedades morfológicas, elétricas e ópticas. Os resultados alcançados nos permitem afirmar que o sulfeto de antimônio bidimensional tem grande potencial para aplicações em dispositivos fotossensíveis na escala nanométrica.
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    Exfoliation and characterization of a two-dimensional serpentine-based material.
    (2019) Santos, Joyce Cristina da Cruz; Barboza, Ana Paula Moreira; Matos, Matheus Josué de Souza; Barcelos, Ingrid David; Fernandes, Thales Fernando Damasceno; Soares, Edmar Avellar; Moreira, Roberto Luiz; Neves, Bernardo Ruegger Almeida
    We report on an experimental investigation of serpentine, an abundant phyllosilicate, as an alternative source of two-dimensional (2D) nanomaterials. We show, through scanning probe microscopy (SPM) measurements, that natural serpentine mineral can be mechanically exfoliated down to few-layer flakes, where monolayers can be easily resolved. The parent serpentine bulk material was initially characterized via conventional techniques like XRD, XPS, FTIR and Raman spectroscopies and the results show that it is predominantly constituted by the antigorite mineral. From ab initio calculations using density functional theory, we also determine the geometry and electronic structure of antigorite, the observed structural form of serpentine. Additionally, we further characterized electrical and mechanical properties of the obtained 2D material flakes using SPM and broadband synchrotron infrared nanospectroscopy. Wavelength tuning of the serpentine vibrational resonances, assigned to in- and out-of-plane molecular vibrations, are observed and compared with the FTIR characterization of the parent bulk material. They show that there is no degradation of serpentine's structural properties during its mechanical exfoliation down to nanometer-thin sheets. Therefore, our results introduce the serpentine mineral as an attractive low-cost candidate in 2D materials applications.
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    High throughput investigation of an emergent and naturally abundant 2D material : clinochlore.
    (2022) Gonçalves, Raphaela de Oliveira; Guallichico, Luis Antonio Guallichico; Policarpo, Eduardo; Cadore, Alisson Ronieri; Freitas, Raul de Oliveira; Silva, Francisco Mateus Cirilo da; Teixeira, Veronica de Carvalho; Paniago, Roberto Magalhães; Chacham, Helio; Matos, Matheus Josué de Souza; Souza, Angelo Malachias de; Krambrock, Klaus Wilhelm Heinrich; Barcelos, Ingrid David
    Phyllosilicate minerals, which form a class of naturally occurring layered materials (LMs), have been recently considered as a low-cost source of two-dimensional (2D) materials. Clinochlore [Mg5Al(AlSi3)O10(OH)8] is one of the most abundant phyllosilicate minerals in nature, exhibiting the capability to be mechanically exfoliated down to a few layers. An important characteristic of clinochlore is the natural occurrence of defects and impurities which can strongly affect their optoelectronic properties, possibly in technologically interesting ways. In the present work, we carry out a thorough investigation of the clinochlore structure on both bulk and 2D exfoliated forms, discussing its optical features and the influence of the insertion of impurities on its macroscopic prop- erties. Several experimental techniques are employed, followed by theoretical first-principles calculations considering several types of naturally-ocurring transition metal impurities in the mineral lattice and their effect on electronic and optical properties. We demonstrate the existence of requirements concerning surface quality and insulating properties of clinochlore that are mandatory for its suitable application in nanoelectronic devices. The results presented in this work provide important informations for clinochlore potential applications and establish a basis for further works that intend to optimize its properties to relevant 2D technological applications through defect engineering.