Structural Investigation and Functional Properties of Mg_xNi_(1-x)Fe_2O_4 Ferrites

摘要

The preparation, structural, microstructural, dielectric, and low temperature magnetic properties of Mg_xNi_(1-x)Fe_2O_4 (x = 0, 0.17, 0.34, 0.50, 0.66, 0.83, 1) ferrites synthesized by using a self-combustion sol-gel method is presented. Good insulating properties were found for all the compositions at high frequencies (kHz and MHz range), which might drive the present ceramics as interesting for RF/microwaves applications. By increasing the Mg~(2+) concentration, the total resistivity strongly increases (from ～10~6 Ωm for the Ni ferrite to 10~9 Ωm for the Me ferrite), corresponding to conductivities in the range 10~(-9)-10~(-6)S/m at f= 1 Hz. Typical ferrimagnetic character with a small coercivity and saturation magnetization in the range (30-50) Am~2/kg, which slightly decreases with increasing the Mg content, were found. On the basis of the combined results from the infrared spectroscopy and XRD analysis, it was shown that the magnetic properties depend on the Mg~(2+) ions distribution on the octahedral and tetrahedral sites and the experimental saturation magnetization allowed to compute the cation distribution for the Mg_xNi_(1-x)Fe_2O_4 ferrites.