Polycrystalline Samples
Mostrando 13-24 de 51 artigos, teses e dissertações.
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13. Desenvolvimento de microcélula eletroquímica para estudos de microrregiões
The construction and optimization of a device that can be applied to electrochemical studies in flat micro regions are described. This was developed as an attempt to study small regions of metallic samples, whose properties may differ completely from its macroscopic behavior and for studies in highly resistive medium. Some results were obtained for individua
Química Nova. Publicado em: 2012
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14. PROCESSAMENTO, CARACTERIZAÇÃO E ESTUDO DE FENÔMENOS CRÍTICOS NOS SISTEMAS SUPERCONDUTORES (Er,Gd)1−xPrxBa2Cu3O7 / PROCESSAMENTO, CARACTERIZAÇÃO E ESTUDO DE FENÔMENOS CRÍTICOS NOS SISTEMAS SUPERCONDUTORES (Er,Gd)1−xPrxBa2Cu3O7
Neste trabalho foram estudados os efeitos das flutuações térmicas na condutividade elétrica de amostras policristalinas com base nos supercondutores Er1xPrxBa2Cu3O7 e Gd1xPrx Ba2Cu3O7. A quantidade de Pr considerada foi x = 0, 00, 0, 05 e 0, 10. As amostras foram preparadas pela técnica padrão de reação de estado sólido e caracterizadas por microsco
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/11/2010
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15. Conductivity fluctuations of polycrystalline Ag-doped YBa2Cu3O7-δ superconductor
Systematic conductivity measurements near T C in granular Ag-doped YBa2Cu3O7-δ superconductors are presented. Silver doped YBa2Cu3O7-δ samples were produced by different routes and characterized by X-ray diffraction, dc magnetization and electrical resistivity. The results were analyzed in terms of the temperature derivative of the resistivity and of the l
Brazilian Journal of Physics. Publicado em: 2010-06
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16. Microstructural and nonohmic properties of ZnO.Pr6O11 CoO polycrystalline system
The microstructure and electrical properties of varistors composed of (95-x) ZnO + x Pr6O11 + 5 CoO (ZPC), (x = 0.1, 0.5 and 1.0) and sintered at 1300 and 1350 °C, were investigated. According to X-ray diffraction, several phases (ZnO, Pr2O3 and Pr2CoO4) are present when x = 1.0. Using Scanning Electron Microscopy, all of these compositions contain precipit
Materials Research. Publicado em: 2010-03
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17. Analysis of fluctuation conductivity of polycrystalline Er1-xPr xBa2Cu3O7-δsuperconductors
In this work we report on conductivity fluctuation measurements in polycrystalline samples of the Er1-xPr xBa2Cu3O7-δ superconductor (x = 0.00, 0.05 and 0.10). Samples were prepared by a standard solid-state reaction technique. The results were analyzed in terms of the temperature derivative of the resistivity and of the logarithmic temperature derivative o
Brazilian Journal of Physics. Publicado em: 2009-12
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18. Effects of Ag addition on some physical properties of granular YBa2Cu3O7-δ superconductor
The effects of Ag addition on some physical properties of YBa2Cu3O7-δ superconductor has been studied. The samples were produced by different routes and characterized by scanning electron microscopy, differential thermal analysis, thermogravimetric analysis, X-ray diffraction and nanoindentation. The superconducting properties were studied by dc magnetizati
Brazilian Journal of Physics. Publicado em: 2009-12
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19. Texture analysis of deformation induced martensite in an AISI 301L stainless steel: microtexture and macrotexture aspects
Experiments have been conducted to study the strain induced transformation from austenite to martensite in a metastable AISI 301LN austenitic stainless steel, deformed by uniaxial tension applied along rolling direction. Samples deformed 10 and 20% have shown the presence of α´ martensite phase. Measured pole figures of martensite phase were compared to ca
Materials Research. Publicado em: 2009-09
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20. Structural and dielectric properties of ZrO2 added (Na1/2Bi1/2)TiO3 ceramic
Polycrystalline samples of ZrO2 added (Na1/2Bi1/2)TiO3 were prepared using high-temperature solid-state reaction method at 1050ºC and subsequent sintering at 1090ºC in air atmosphere. Rietveld analyses of XRD data indicated the formation of a single-phase hexagonal structure with R3c symmetry. Dielectric studies revealed the relaxor behaviour. The addition
Brazilian Journal of Physics. Publicado em: 2009-06
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21. Spectroscopies of photoluminescence and excitation of MgGa2O4 samples doped with Mn2+. / Espectroscopia de fotoluminescência e excitação de amostras MgGa2O4 dopadas com Mn2+
This work presents the room temperature photoluminescence and excitation spectroscopes data of MgGa2O4 samples doped with 0.5% and 10.0% Mn2+. The polycrystalline samples were produced by solid-state reaction at high temperature and characterized with X ray Diffraction and SEM. The photoluminescence spectra showed emission at green and red spectral regions,
Publicado em: 2009
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22. Performance of 3Y-TZP bioceramics under cyclic fatigue loading
In this work, the static mechanical properties and cyclic fatigue life of 3 mol. (%) Y2O3-stabilized tetragonal zirconia polycrystalline (3Y-TZP) ceramics were investigated. Pre-sintered samples were sintered in air at 1600 °C for 120 minutes, and characterized by X ray diffraction and scanning electronic microscopy. Hardness and fracture toughness were det
Materials Research. Publicado em: 2008-03
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23. Transição ordem-desordem da matéria de vórtices em supercondutores detectada através do terceiro harmônico da suscetibilidade AC
Although a vortex state, in type II superconductors, has been anticipated more than 50 years ago, a great deal of theoretical and experimental efforts has still been done in an attempt to investigate how the dynamics of these structures depends on external excitations and on the inherent properties of the underlying superconducting material, such as inhomoge
Publicado em: 2008
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24. Propriedades estruturais e microestruturais de manganitas dopadas com cobre
We report a structural study on polycrystalline La0.86Sr0.14Mn1-y Cu yO3+delta samples (y = 0, 0.05, 0.10, 0.15, 0.20) using refinement of powder X-ray diffraction data and analysis of scanning electron microscopy images. It is found that the structure remains rhombohedral through the whole series, with a decrease in the average Mn-Mn bond distances, slight
Química Nova. Publicado em: 2007