20 resultados para Magnetic particle


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This work involved the synthesis and characterization of Cu0.5Zn0.5Fe2O4 ferrite powders prepared by combustion reaction for use as soft magnetic materials. The powders were characterized by nitrogen adsorption (BET), XRD, Rietveld refinement, SEM, TEM and magnetic measures. The results indicate that the combustion reaction yielded crystalline powders containing spinel ferrite as the primary phase and traces of Fe2O3 as secondary phase. The crystallite size and lattice microdeformation calculated from Rietveld refinements were 36 and 0.24 nm, respectively. The micrographic analysis revealed particles smaller than 100 nm and fine particle agglomerates. The particles were approximately spherical and their size, calculated by TEM, was 29 nm. The magnetic parameters indicated that the Cu-Zn ferrite powders presented closed hysteresis loops and soft magnetic properties. © (2012) Trans Tech Publications, Switzerland.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Using the Feynman procedure of ordered exponential operators we solve the evolution equations for a two-neutrino system considering arbitrarily varying matter density and magnetic field along the neutrino trajectory. We show that a large geometrical phase velocity suppresses νL→νR transitions unless some stationary trajectory is found along the neutrino path. Concerning the solar neutrino case, if we admit the standard solar model matter distribution, no such trajectory can be found.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)