Examinando por Materia "Mössbauer spectrometry"
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- PublicaciónSólo datosStructural and Magnetic Properties Study of Fe50Si50 Powders with Different Microparticle Sizes(Journal of Superconductivity and Novel Magnetism, 2018-08-22) Trujillo Hernández, Juan Sebastián; González Perdomo, Jhon Fredy; Oyola Lozano, Dagoberto; Rojas Martínez, Yebrayl; Pérez Alcázar, Germán; Bustos Rodríguez, HumbertoThe structural properties and magnetic behavior of the Fe50Si50 system were determined using X-ray diffraction (XRD), Mössbauer spectrometry (MS), vibration sample magnetometry (VSM), and scanning electron microscopy (SEM). Samples of Fe50Si50 were melted using an arc furnace, then powder was obtained through a diamond file, and this was passed through different sieves. Finally, nanoparticles of this system were produced by means of surfactant-assisted mechanical alloying. XRD confirmed the presence of the FeSi (CS) and Fe5Si3 structural phases. By transmission MS, it was observed that at room temperature the spectrum is formed by three general components, a doublet associated with the FeSi (CS) phase and two sextets associated with the Fe5Si3 phase; this gives the idea of the distribution of the sizes of particles present in the sample. By VSM, the soft magnetic behavior of the system was ratified and it was determined that the biggest saturation magnetization corresponds to the smallest particles.
- PublicaciónSólo datosTheoretical and experimental study of FeSi on magnetic and phase properties(Applied Physics A: Materials Science and Processing, 2020-10-10) Piamba, J. F.; Ortega, C.; Hernández-Bravo, R.; González Carmona, J. M.; Tabares, J. A.; Pérez Alcázar, G. A.; Alvarado-Orozco, J. M.In the present work, the structural, magnetic, and theoretical analysis of the Fe–Si alloy prepared by melting and heat-treated was performed. The ordered FeSi simple cubic (sc) phase was obtained by melting and heat treatment processes as determined by X-ray diffraction. The presence of the superstructure peak in the (312) crystalline direction confirms the high structural order reached. Using Mössbauer spectrometry (MS), a paramagnetic behavior with quadrupole splitting of SQ = 0.53 ± 0.02 mm/s was obtained. Although MS indicates paramagnetic behavior, vibrating sample magnetometry (VSM) showed ferromagnetic behavior with a coercive field of 25 Oe, associated with a small amount of Fe3Si segregations detected by scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). Using density functional theory (DFT), the crystalline structures for the simple cubic (sc) Fe50Si50, face-centered cubic (fcc) Fe3Si, and body-centered cubic (bcc) Fe3Si crystalline structures were simulated. Electron total density values were calculated to perform energetic comparisons with magnetic behavior. The electronic structures and magnetic properties of the Fe–Si alloys in different stoichiometric configurations were calculated by CASTEP, which employed first principles DFT. The density of states (DOS) and band structures were calculated together with magnetic properties. The results showed that the high value of the polarization spin for the fcc and bcc structures is due to the contribution of the high amount of Fe atoms above the Si atoms, which is reflected in an increase in the magnetic moment and that their presence could explain the ferromagnetic behavior observed by VSM.