Orientador : Prof. Dr. Marcelo de Paiva de Souza / Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Humanas, Programa de Pós-Graduação em Letras. Defesa: Curitiba, 29/09/2016 / Inclui referências : f. 139-141 / Resumo: The present work reports on the results of experimental investigations about the structural and the electrical properties of bismuth (Bi) and manganese (Mn) compound films with different relative atomic content, grown by thermal evaporation on glass substrates. The structural analysis comprised profilometry, X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and the analysis of the electrical properties comprised the obtainment of voltage versus current (VxI) curves with the variation of the temperatures. The structural analysis revealed that the films have granular structure, where the grain shape varied from polyhedral form on the absence of Mn to a smoothed surface irregular shape as Mn was added. All samples showed X-ray diffraction peaks associated to phases of Bi and Bi oxides, and the samples with Mn revealed some crystalline phases containing Bi and its oxides. The film of pure Mn revealed only an amorphous phase. Chemical analysis by EDS showed the presence of significant amount of unintentional C and O elements, the first of them not chemically associated to elements Bi or Mn. IxV curves traced for Bi - Mn films on the four-point planar architecture revealer ohmic character. From the resistivity curves as a function of the temperature the activation energies were obtained. The IxV curves revealed an unexpected nonzero offset (parallel displacement along the voltage axis) apparently not associated to either photoelectric, thermoelectric, magnetoelectrics effects, or even experimental artifacts. It was investigated the electrical behavior of a Bi film along the transversal geometry. Two of such devices presented a slight non-linearity at room temperatures, which gradually increased with the reduction down to 20 K. Two other devices presented a sudden jump on the non-linearity in the temperature window of about 80 - 90 K, and below that, the behavior the variation pursued slowly. This non-linearity is assigned by us to the effect of potential barriers formed at the microscopic level granulations throughout which the flow of electric current occurs via tunneling. At present moment it is not envisaged the nature of the mechanism that governs the sudden increase of the non-linearity. / Abstract: The present work reports on the results of experimental investigations about the structural and the electrical properties of bismuth (Bi) and manganese (Mn) compound films with different relative atomic content, grown by thermal evaporation on glass substrates. The structural analysis comprised profilometry, X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and the analysis of the electrical properties comprised the obtainment of voltage versus current (VxI) curves with the variation of the temperatures. The structural analysis revealed that the films have granular structure, where the grain shape varied from polyhedral form on the absence of Mn to a smoothed surface irregular shape as Mn was added. All samples showed X-ray diffraction peaks associated to phases of Bi and Bi oxides, and the samples with Mn revealed some crystalline phases containing Bi and its oxides. The film of pure Mn revealed only an amorphous phase. Chemical analysis by EDS showed the presence of significant amount of unintentional C and O elements, the first of them not chemically associated to elements Bi or Mn. IxV curves traced for Bi - Mn films on the four-point planar architecture revealer ohmic character. From the resistivity curves as a function of the temperature the activation energies were obtained. The IxV curves revealed an unexpected nonzero offset (parallel displacement along the voltage axis) apparently not associated to either photoelectric, thermoelectric, magnetoelectrics effects, or even experimental artifacts. It was investigated the electrical behavior of a Bi film along the transversal geometry. Two of such devices presented a slight non-linearity at room temperatures, which gradually increased with the reduction down to 20 K. Two other devices presented a sudden jump on the non-linearity in the temperature window of about 80 - 90 K, and below that, the behavior the variation pursued slowly. This non-linearity is assigned by us to the effect of potential barriers formed at the microscopic level granulations throughout which the flow of electric current occurs via tunneling. At present moment it is not envisaged the nature of the mechanism that governs the sudden increase of the non-linearity.
| Identifer | oai:union.ndltd.org:IBICT/oai:dspace.c3sl.ufpr.br:1884/45217 |
| Date | January 2016 |
| Creators | Massa, Isadora Bortoluzzi |
| Contributors | Universidade Federal do Paraná. Setor de Ciências Humanas. Programa de Pós-Graduação em Letras, Souza, Marcelo Paiva de |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | 142 f : il. , algumas color., application/pdf |
| Source | reponame:Repositório Institucional da UFPR, instname:Universidade Federal do Paraná, instacron:UFPR |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Disponível em formato digital |
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