RESUMEN
Mn1-x Zn x 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 Mn1-x Zn x 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 Mn1-x Zn x Fe2O4 ferrofluids. The Mn1-x Zn x 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 Mn1-x Zn x Fe2O4 ferrofluids prepared in this work may serve as a future platform for advancing magnetic sensors and radar absorbing materials.
