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| Author(s): |
Eric Perim Martins
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2014-02-25 |
| Examining board members: |
Douglas Soares Galvão;
Ado Jorio de Vasconcelos;
Eunezio Antonio de Souza;
Daniel Mário Ugarte;
Luiz Eduardo Moreira Carvalho de Oliveira
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| Advisor: | Douglas Soares Galvão |
| Abstract | |
In this work we investigate structural, dynamical, mechanical and electronic properties of different nanostructures. The thesis is organized in three distinct parts, in the first we analyze some aspects related to nanoscrolls made from different materials, in the second we investigate two dimensional porous boron nitride structures and, in the third, we study novel one dimensional silicon and germanium nanostructures. Nanoscrolls are structures formed by rolling layered materials around a well defined axis and present interesting and unique properties. Besides preserving electronic and mechanical properties shown by nanotubes, nanoscrolls, as a consequence of their open ended morphology, present great radial flexibility and large solvent accessible surface area, making them interesting candidates for aplications as nanoactuators, both mechanical and electronic, and as hydrogen storage mediums. Firstly, we approach aspects related to carbon and boron nitride nanoscrolls synthesis processes, both already having been experimentally produced. We then focus on the first published works on nanoscrolls formed from carbon nitride, studying their stability and dynamical properties. Lastly, we analyze the confinement laws of nanoscrolls inside nanotubes, demonstrating the failure of classical continuous elasticity on solving this problem due to electronic effects. Two dimensional nanostructures have been extensively studied since the successful isolation of monolayer graphene and the confirmation of its highly interesting mechanical and electronic properties. Naturally, other materials with similar characteristics are pursued and, due to its large structural similarity, hexagonal boron nitride has been of great interest, presenting higher thermal and chemical stability when compared to graphene. We investigated two dimensional porous boron nitride structures with distinct morphologies. These structures, besides preserving hexagonal boron nitride desirable properties, are characterized by their low density and the presence of large pores, which can be utilized in applications such as selective filters. We also show the possibility of bandgap tuning through carbon atoms substitution. Due to significant similarities between their electronic structures and that of carbon, silicon and germanium are able to generate a plethora of interesting nanostructures, analogous to the existing carbon ones. Nevertheless, there are notable differences, such as the manifestation of the pseudo-Jahn Teller effect which leads to nanostructures with distinct morphologies. With this in mind, we investigate the possibility of these differences leading to the existence of unique silicon and germanium nanostructres, with no carbon analogue and we show one dimensional structures satisfying such conditions. We study their stability and their mechanical and electronic properties, showing that their bandgap values can be controlled by compressive and tensile strain (AU) | |
| FAPESP's process: | 09/17849-3 - Conformational, Electronic and Structural Properties of Nanoscrolls Formed From Different Materials and Topologies |
| Grantee: | Eric Perim Martins |
| Support Opportunities: | Scholarships in Brazil - Doctorate |