Resumo

HUSSAIN, A. et al. A study on microstructure and magnetic properties of nanostructured Co_xNi_1-xMn_0.5Fe_1.5O₄ (x = 0,0.25,0.5,0.75,1)spinel ferrites. Rev. mex. fis. [online]. 2021, vol.67, n.3, pp.527-535.  Epub 21-Fev-2022. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.67.527.

A low-temperature synthesis of novel nanostructured CoxNi1-xMn0.5Fe1.5O4 (x = 0,0.25,0.5,0.75,1) ferrites was carried out by sol-gel auto-combustion technique. The obtained nanostructured ferrites were investigated by employing the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). The XRD diffractograms of the prepared ferrites revealed the formation of a spinel phase with face-centered cubic (fcc) structure belonging to the Fd-$\overline{3}$ m space group. The average lattice parameter ‘a’ of ferrites exhibited a rise versus a rise in CO2+ concentration following Vegard’s law. The SEM investigation of NiMn0.5Fe1.5O4 powder revealed the existence of octahedral-shaped morphology of ferrite grains. The TEM investigation of NiMn0.5Fe1.5O4 powder showed nanostructures of ferrite particles with sizes consistent with the crystallite sizes as estimated by Debye-Scherer’s formula. An EDX spectrum of NiMn0.5Fe1.5O4 powder confirmed its elemental composition. The M-H hysteresis loops recorded by VSM at room temperature revealed a dependence of coercivity (Hc), maximum magnetization (Mmax), and retentivity (Mr) on CO2+ concentration. The shape dependence of M-H loops on CO2+ concentration in compounds enabled their candidature for applications in memory devices and magnetic sensors.

Palavras-chave : Sol-gel technique; spinel structure; X-ray diffraction; scanning electron microscopy; coercivity; remanence.