Influence of composition optimization on soft magnetic MnZn ferrites
The soft magnetic MnZn ferrite materials Mn0.5-yZn0.5Fe2+yO4(y=0,0.01,0.03,0.05,0.07,0.09)were prepared by the chemical sol-spray drying-calcination method.X-ray diffraction(XRD),Fourier transform infrared(FTIR)spectroscopy,Raman spectroscopy,X-ray photon-electron spectroscopy(XPS),scanning electron microscope(SEM),transmission electron microscopy(TEM),and superconducting quantum interference magnetic measurement system were used to characterize the samples.The results indicate that the samples are all single-phase MnZn ferrite when y=0-0.07.When y=0.09,α-Fe2O3 impurity phase will appear,which is supported by the XRD and Raman spectroscopy results.With the increase of Fe content,the average crystallite size decreases and then increases.The average crystallite size reaches minimum value when y=0.03.The valences of Fe and Zn are+3 and+2 respectively,while Mn exhibits three valence states of+2,+3,and+4.When y=0.09,the environment in which Fe3+is located in MnZn ferrite and α-Fe2O3 phase is different,and the Fe2p3/2 peak has three sub peaks with binding energies of 710.09,711.16 and 713.71 eV,respectively.The content of Mn2+in the samples first increases and then decreases,reaching its maximum at y=0.07.The samples all present hollow spherical shell morphology composed of small particles,with highly uniform distribution of elements.Also,there is almost no non-hollow spherical shell morphology.When y=0-0.09,the specific saturation magnetizations(Ms)are 41.15-54.58 A·m2/kg,the remanences(Mr)are 0.91-6.50 mA/m,the coercivities(Hc)are 2 242.4～8 917.6 A/m,and the squareness ratios(Mr/Ms)are 0.02-0.12.When the content of Fe is excessive,specific saturation magnetization(Ms)shows a trend of first increasing and then decreasing.And when y=0.07,the comprehensive characteristics of MnZn ferrite are optimal.
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