Study of structural, vibrational, elastic and magnetic properties of uniaxial anisotropic Ni-Zn nanoferrites in the context of cation distribution and magnetocrystalline anisotropy

Abstract

Co-precipitation method was adopted to obtain zinc ferrite nanoparticles substituted with nickel (0.5 ≤ x ≤ 0.7) followed by sintering at 500 °C for 2 h. The formation of spinel ferrite phase in the present ferrite compositions was confirmed from the X-ray diffractograms. The experimental lattice parameter (a) and average crystallite size (<DXRD>) are in between 8.359 - 8.348 Å and 12.8 – 14.9 nm. As doping level of Ni2+ increases, an interesting relation was existed in between a and<DXRD>, such that the first one is decreasing and the later one is increasing. The variation of average particle size (<DFE-SEM>) from FE-SEM is different from the variation of<DXRD>. The present spinel ferrite Ni0.6Zn0.4Fe2O4 possessed smaller particle size of 17.6 nm. The existence of higher and lower vibrational frequencies in between 579–587 cm−1 and 380–386 cm−1, satisfied the Waldron proposals for the ferrite phase. The variations of elastic moduli are very interesting and tricky when compared to the reported literature. The consistency of Poisson’s ratio for these ferrite compositions, revealed the isotropic behavior of present ferrite systems. The saturation magnetization (MS) at room temperature (RT) has uneven variation and a highest value of 43.2 emu/g was noticed for the composition x = 0.6. The coercivity (HC) at RT is gradually increasing with the doping level of Ni2+ ion incorporation. As temperature is decreasing below the room temperature both the MS and HC are increasing for a particular composition. The blocking temperature (TB) lies in the range of 80–125 K and is increasing with the increase of Ni2+ ion concentration. The findings of the present study were discussed in terms of cation distribution and magnetocrystalline anisotropy presuming core-shell morphology.