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Previous issue date: 2016-03-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A capacidade de manipular propriedades t?rmicas de super-redes pode ajudar na descoberta de materiais mais promissores para aplica??es na nanotecnologia. Por meio de simula??es de din?mica molecular de n?o-equil?brio, investigamos o transporte t?rmico em nanofitas BNC, revezando periodicamente quantidades equivalentes de grafeno e nitreto de boro ao longo do seu comprimento, nomeando de per?odo de rede o tamanho de cada par de dom?nio (grafeno-nitreto de boro). Este trabalho revela que a condutividade t?rmica nessa super-rede varia n?o-monotonicamente com o per?odos de rede, podendo dessa forma ser controlada de acordo com os dom?nios de grafeno e nitreto de boro. Isso possibilita identificar o per?odo de rede que fornece a menor condu??o de calor nessa super-rede. Nesse sentido, para nanofitas com per?odo de rede de 3,43 nm, registramos uma condutividade t?rmica de ~ 89 W/m?K. Este valor ? muito menor do que o encontrado para grafeno e nitreto de boro isolados. O transporte t?rmico em nanofitas BNC ? dominado por vibra??es na sua rede cristalina (f?nons). Associamos o comportamento n?o-monot?nico da condutividade t?rmica dessa super-rede com o transporte t?rmico de f?nons coerentes e incoerentes. Por meio da densidade de estados vibracionais (VDOS) e da dispers?o de f?nons, analisamos seu espectro vibracional. / The ability to manipulate thermal properties of superlattices can help in finding
the most promising materials for applications in nanotechnology. Through nonequilibrium
molecular dynamics simulations, we investigate the thermal transport in
graphene-boron nitride nanoribbons (BNC nanoribbons), alternating periodically equivalent
amounts of graphene and boron nitride along its length, by naming the size of
each domain pair (graphene-boron nitride) a lattice period. This work shows that
the thermal conductivity in BNC nanoribbons varies non-monotonically for different
lattice periods, which can thus be controlled according to the domains of graphene
and boron nitride. This allows the identification of a lattice period that provides the
lowest heat conduction in these superlattices. Accordingly, for nanoribbons with lattice
period 3; 43 nm, we find a thermal conductivity of 89 W=m K. This value is
much lower than the value found for both graphene and boron nitride isolated. The
thermal transport in BNC nanoribbons is dominated by vibrations in their crystal lattice
(phonons). We associate this non-monotonic behavior of the thermal conductivity
of this super-lattice with the thermal transport of coherent and incoherent phonons.
Through the density of vibrational states (VDOS) and phonon dispersion we analyze
its vibrational spectrum.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21498 |
| Date | 29 March 2016 |
| Creators | F?lix, Isaac de Mac?do |
| Contributors | 03136125444, Barbosa, Anderson Luiz da Rocha, 04704565661, Bezerra, Claudionor Gomes, 60992565472, Azevedo, S?rgio Andr? Fontes, 38016532500, Pereira, Luiz Felipe Cavalcanti |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM F?SICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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