Fabrication of Mn1Zn Fe2O4 ferrofluids from natural sand for magnetic sensors and radar absorbing materials

Abstract

Mn_1-<i>x</i> Zn _<i>x</i> Fe₂O₄ ferrofluids were produced from natural sand for magnetic sensors and radar absorbing materials. The X-ray diffraction data showed that the Zn partially substituted the Mn and Fe ions to construct a spinel structure. The increasing Zn composition decreased the lattice parameters of the structure. The transmission electron microscopy images showed that the filler Mn_1-<i>x</i> Zn _<i>x</i> Fe₂O₄ nanoparticles tended to agglomerate in three dimensions. Lognormal and mass fractal models were used to fit the small-angle X-ray scattering data of the ferrofluids demonstrated that the ferrofluids formed chain-like structures with a fractal dimension of 1.12-1.67 that was constructed from primary particles with sizes of 3.6-4.1 nm. The filler, surfactant, and carrier liquid of the ferrofluids were confirmed by the functional groups of the metal oxides, tetramethylammonium hydroxide, and H₂O, respectively. The secondary particles contributed to the saturation magnetization of the Mn_1-<i>x</i> Zn _<i>x</i> Fe₂O₄ ferrofluids. The Mn_1-<i>x</i> Zn _<i>x</i> Fe₂O₄ ferrofluids demonstrated excellent performance as magnetic sensors with high stability, especially compared with MnFe₂O₄ ferrofluids. Furthermore, the ferrofluids exhibited excellent radar absorbing materials. The Mn_1-<i>x</i> Zn _<i>x</i> Fe₂O₄ ferrofluids prepared in this work may serve as a future platform for advancing magnetic sensors and radar absorbing materials.