Structural and dielectric properties of Ni0,1Zn0,5Co0,4Fe2O4 ferrite nanoparticles

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Abstract
08-067 Tayanne Cristina Marques Araújo Pereira Pereira, T.C.(Federal University of Maranhão); Borges, M.F.(Federal University of Maranhão); Fonseca, R.d.(Federal University of Maranhão); Castro Junior, M.C.(Federal Institute of Education, Science and Technology of Maranhão); Menezes, A.S.(Federal University of Maranhão); Barros Filho, A.K.(Federal University of Maranhão); Silva, F.C.(Federal University of Maranhão); Sinfrônio, F.S.(Federal University of Maranhão); Magneto-dielectric ferrites are widely used as component for telecommunication devices, computer circuits, power supplies, variable frequency filters, magnetic recording systems and electromagnetic wave absorbers. Thus, cobalt-doped Ni-Zn spinel ferrites nanoparticles (Ni0,1Zn0,5Co0,4Fe2O4) were synthesized by microwave-assisted hydrothermal method. The effect of the irradiation time on the microstructural, phonic and dielectric was evaluated by means of X-ray diffraction (XRD), Raman spectroscopy and impedance spectroscopy techniques, respectively. The dielectric properties such as real (?') and the imaginary part (?") of the permittivity, dielectric loss tangent (tan ?) and AC conductivity (?) has been evaluated over a wide range of frequencies (1 Hz - 1 MHz). XRDP patterns suggested that all samples were crystalized as cubic single-phase structures with Fd3 ?m space group. According to the Rietveld refinement and William-Hall Equation the average crystallite size of ferrites was approximately 7.5 nm whereas its macrostrain was lower than 0.002 %. X-ray density (theoretical) of the samples were estimated at about 5.3 gm.cm-3. Raman spectra exhibit five first order Raman active modes (A1g?Eg?3T2g), suggesting a substantial organization of the crystal on short- and long-ranges. At room temperature, both ?' and ?" shows decrease inversely proportional to the frequency, keeping constant at higher frequencies. Comparable behaviour was detected for tan (?). Conversely, AC conductivity increased with the increase in the frequency. Grain and grain boundary contributions to total impedance was estimated by means of Brick Layer model.
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