Structural and magnetic studies on Mn-doped Ni–Zn ferrite nanoparticles

Abstract

Ni–Zn ferrite nanoparticles with manganese substitutions, Ni0.4Zn0.6−x Mn x Fe2O4, where x varies from 0.00 to 0.25 in steps of 0.05, were prepared using sol–gel autocombustion method. The resultant nanoparticles were analyzed using X-ray diffractometry, transmission electron microscopy, thermogravimetry and vibrating sample magnetometer measurements. X-ray diffraction patterns confirm single-phase cubic spinel structures with crystallite sizes in the range from 25.43 to 37.23 nm. Particle sizes obtained from transmission electron micrographs were also in good agreement with the crystallite sizes obtained from the X-ray data. Saturation magnetization and coercivity data for all the samples obtained from the corresponding M–H loops suggest a sinusoidal variations with Mn concentration (x) implying that the substitution of Mn in the given nano-sized Ni–Zn ferrite system seems to have brought in a profound influence not only on the site preferences of other cations in the system but also in bringing about modifications in its own site preferences. The results are analyzed in terms of the compositional and structural modifications, and it was found that the observed magnetic variation was governed by the crystallite size and the corresponding change in cationic preferences in these materials.