Cationic charge influence on the magnetic response of the Fe3O4–[Me21−+yMe3y+ (OH2)]y+(Co32−)y/2·mH2O hydrotalcite system

This work reports the influence of cationic charge on the magnetic response of hydrotalcites combined with magnetite nanoparticles. Fe3O4 particles were synthesized by the co-precipitation method, and the resulting magnetic particles were dispersed. A mixture of Mg, Me (Ni, Co, Sr), and Al nitrates with stoichiometric Me2+/Me3+ molar ratios of 2 and 3 was added. X-ray diffraction patterns revealed the presence of Fe3O4 and hydrotalcite main phases and some secondary phases in the Sr2+-modified sample. The FTIR spectra provided information on the chemical structure of the materials and confirmed the presence of representative vibrational bands for the composite structure. N2 adsorption–desorption isotherms analyzed by the BET method indicated remarkable porous properties for the synthesized samples, and higher surface areas of 160 and 145 m2/g were obtained for Fe3O4MgCoAl x = 3 and Fe3O4MgNiAl x = 3, respectively, with an increasing modifying cation ratio. The morphological characterization through SEM showed that a higher content of divalent cations favors the formation of larger particles, reaching a particle size of 786 nm for the sample with Ni2+ addition. The magnetic measurements showed marked ferromagnetic behavior with variations in saturation and remanent magnetizations due to the influence of modifying cations. The analysis revealed a correlation between the cationic charge and the magnetic and structural properties of the hydrotalcites, suggesting effective control over the magnetic properties by manipulating the cationic charge in these composite materials. © 2025 Elsevier B.V., All rights reserved.