Quasi Crystals
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. Solid-state Morphology Evolution of Sodium Neutralized Poly(ethylene-ran-methacrylic acid) Ionomer Under Dry and Wet Thermal Annealing
The DSC low temperature endothermic peak shown by sodium neutralized poly(ethylene-random-methacrylic acid) (E/MAA-Na+) ionomers in the range of 50-70 ºC is attributed to the endothermic reordering of polyethylene chain segments belonging to two populations of quasi-crystals set from melt, initially showing no birefringence. Dry or wet thermal annealing imp
Mat. Res.. Publicado em: 08/08/2019
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2. Propriedades dinâmicas e ergódicas de shifts multidimensionais / Dynamic and ergodic properties of multidimensional shifts
Focaremos sobre aspectos dinâmicos e ergódicos de shifts multidimensionais, atentando especialmente para suas relações com estados fundamentais e quase-cristais em reticulados. Por exemplo, em mecânica estatística, dado um potencial invariante por translação, seus estados fundamentais são medidas de probabilidade invariantes por translação suporta
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 15/08/2011
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3. Effect of zinc crystals size on galvanized steel deformation and electrochemical behavior
Hot-dip galvanized steel sheets with different spangle sizes were deformed by means of rolling and tension. The change of preferential crystallographic orientation and of superficial characteristics due to the deformation was analyzed by means of both X-rays diffraction and optical and scanning electronic microscopy. A correlation between such changes and th
Materials Research. Publicado em: 2009-09
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4. Polaritons em materiais magnéticos nanoestruturados
Neste trabalho apresentamos um estudo teórico sobre as propriedades dos polaritons magnéticos em super-redes organizadas em padrões periódico e quasiperiódico. Na super-rede periódica, objetivando descrever o comportamento destes modos, tanto no volume quanto na superfície, foi utilizada a teoria do meio efetivo, que facilita enormemente a álgebra en
Publicado em: 2007
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5. Frenkel-exciton-polaritons in organic microcavities
We study organic microcavities in the strong coupling regime. The cavity exciton-polariton dispersion relations and quantum states are derived in using a microscopic theory. We consider the two cases of anisotropic organic crystals with one and two molecules per unit cell. In general, the cavity exciton-polaritons are a coherent superposition of both cavity
Brazilian Journal of Physics. Publicado em: 2006-06
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6. Magnetization peaks in type II superconductors / Picos da magnetização em supercondutores do tipo II
In this thesis we have studied possible origins for the Second Magnetization Peak (SMP) in high and low critical temperature superconductors, using samples of Bi2Sr2CaCu2O8+d and Nb single crystals. To study the SMP we did measurements of magnetization curves (M x H) and AC susceptibility (vs. h and T). We obtained the creep exponent in the SMP region, using
Publicado em: 2005
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7. CINÉTICA DO ELETRODO DE FES2 / FE EM SAIS FUNDIDOS / FES2 / FE ELECTRODE KINETICS IN MOLTEN SALTS
In this work the measurement of the critical kinetics parameters of iron disulphide electrochemical reduction in molten chloride halides mixture was made. This cathode is applied as alternative material in high technology systems, such as, solar energy collector`s components, anode depolariser for hydrogen production and cathodic materials for high energy de
Publicado em: 2005
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8. Microemulsões a base de óleos vegetais: formação, propriedades e emprego na descontaminação EX-SITU de Solo / Vegetable oil-based microemulsions: formation, properties and application for "exsitu" soil decontamination
In the present project, we were interested in assessing the use of Brazilian vegetable oils in the "ex-situ" decontamination of soils from polycyclic aromatic hydrocarbons (PAHs). In this process, contaminated soil is treated with a microemulsion (µE) composed of water (W) /commercial non-ionic surfactant (S) C9/11EO4 /oil (O). The latter term refers to the
Publicado em: 2000
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9. Propriedades estruturais, densidade de deslocações e analise de defeitos superficiais em heteroestruturas semicondutoras por difração multipla de raios-x
In this work. the potential of the X-Ray Multiple Diffraction (MD) technique in studying the heterostructures and semiconductor substrates is investigated. The three-beam (incident, primary and secondary) MD with the secondary parallel to the surface. is the main tool for this investigation. The occurrence of the two types of hybrid reflections in heterostru
Publicado em: 1994
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10. Quimica do estado solido : preparação, caracterização, comportamento termico e reações topoquimicas em tiometalatos do tipo AM52 (A=K, Ag, Ba e M=Fe)
This is a study on the preparation, characterization, ion-exchange and thermal bahavior of iron potassium sulfide, KFeS2. The structure of this solid is basically composed by edge-sharing FeS4 tetrahedra forming negatively charged linear chains [FeS2]n. Potassium ions act as counter-ion. The Fe-Fe distance within the chains is greater than the distance betwe
Publicado em: 1993
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11. An introduction to the methodology of structure determination by single crystal x-ray diffraction: applications to some complexes of lanthanides and transition metals with organic ligands / Introdução aos métodos de determinação de estruturas por difração de raios-X em monocristais: aplicação a alguns complexos de lantanídeos e metais de transição com ligantes orgânicos
The crystal structure of the complexes Ln(ClO4)3.6[PONH2(C6H5)2] where Ln=Eu, La, Cu[NH2(CH3)2CCO2]2, NiBr2.4[AsO(C6H5)3].8H2O (green), NiBr2.4[AsO(C6H5)3.1,5(CH3C6H5).H2O (orange) and of the ligand PONH2(C6H5)2 have been determined by X-ray diffraction. The complexes involving lanthanide ions refined to final R factors of R(Eu)=0.125 and R(La)=0.133 and the
Publicado em: 1983
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12. Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals
Analysis of the measured values of Q for the weak peaks (small maxima, usually considered to be background fluctuations, “noise”) on the x-ray powder diffraction curves for 17 rapidly quenched alloys leads directly to the conclusion that they are formed by an 820-atom or 1012-atom primitive cubic structure that by icosahedral twinning produces the so-cal