Structural and magnetic characterization of Zr-substituted magnetite (Zr_xFe_3-xO₄, 0≤x≤1)

Abstract

We report the preparation of monophasic Zr-substituted magnetite (Zr_xFe_3-xO₄; 0≤x≤1) nanoparticles by wet chemical route. Such a report is lacking in the literature. Rietveld refinement of the X-ray diffraction (XRD) data suggests continuous decrease in the lattice parameter with increased Zr-substitutions. From TEM analysis, the size of the as synthesized particles was found to be in the range of 5–20 nm. The differential scanning calorimetry (DSC) curves for the samples with different amount of substitutions displayed considerable differences in their behaviors. The room temperature specific magnetization at 2 T has been found to decrease from 50 (x=0.2) to 41 A m²/kg (x=1.0) with increased Zr-substitution. From XRD and magnetic behavior analysis we could suggest that due to occupation of Zr⁴⁺ ions at tetrahedral and octahedral voids of Fe₃O₄, the amount of Fe²⁺ was more at octahedral site for x≤0.4 and at tetrahedral site for x>0.4 respectively. The ferrofluids prepared from these magnetic nanoparticles possessed good heating ability and Specific Absorption Rate (SAR) values suitable for bioapplications.