CCET - DFTE - Artigos publicados em periódicos
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Navegando CCET - DFTE - Artigos publicados em periódicos por Assunto "Alloys"
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Artigo Fe interparticle interactions in Fe_{x}Ag_{100?x} granular alloys (2(American Physical Society, 2005-11-03) Araújo, José Humberto de; Soares, J. M.; Machado, F. L. A.; Cabral, F. A. O.; Ginani, Marconi FloripeSamples of FexAg100−x, with 2% x50%, were produced using a new preparation route based on the ionic coordination reaction technique. X-ray diffraction and transmission electronic microscopy showed that the samples are granular alloys and that they have a high degree of purity, good homogeneity, small variations in the Fe concentration, and the mean size of the grains was approximately 30 nm for any Fe composition. Magnetization measurements showed that the coercive field of the samples presented a fairly complex behav- ior. It was also observed, by means of time decay of the thermoremanent magnetization, three dynamical regimes. The existence of these regimes are in good agreement with what is expected from the analysis using the Henkel and M plots. In addition, it was observed an onset to a long range magnetic order LRMO in the Fe30Ag70 sample, culminating in a superferromagnetic order in Fe50Ag50Artigo Giant magnetoimpedance in FeAg granular alloys(Applied Physics Letters, 2002-04-02) Araújo, José Humberto de; Soares, João Maria; Cabral, F. A. O.; Dumelow, T.We have observed giant magnetoimpedance (GMI) in an FeAg granular alloy. Impedance and transverse susceptibility (TS) measurements as a function of the external dc magnetic field were made at room temperature. The variation of the magnetoimpedance ratio with magnetic field has been related to a corresponding TS ratio change as a function of the magnetic field. The peaks in the GMI and TS curves are in the same position and have been associated in both cases to effective anisotropy fields.