Cationic charge influence on the magnetic response of the Fe 3 O 4 –[Me 2+ 1− y Me 3+ y (OH 2 )] y + (Co 3 2− ) y /2 ·mH 2 O hydrotalcite system

Abstract

This work reports the influence of cationic chargeon the magnetic response of hydrotalcites combined withmagnetite nanoparticles. Fe3O4 particles were synthesizedby the co-precipitation method, and the resulting magneticparticles were dispersed. A mixture of Mg, Me (Ni, Co, Sr), andAl nitrates with stoichiometric Me2+/Me3+ molar ratios of 2and 3 was added. X-ray diffraction patterns revealed the pre-sence of Fe3O4 and hydrotalcite main phases and some sec-ondary phases in the Sr2+-modified sample. The FTIR spectraprovided information on the chemical structure of the mate-rials and confirmed the presence of representative vibra-tional bands for the composite structure. N2 adsorption–desorption isotherms analyzed by the BET method indicatedremarkable porous properties for the synthesized samples,and higher surface areas of 160 and 145 m2/g were obtainedfor Fe3O4MgCoAl x = 3 and Fe3O4MgNiAl x = 3, respectively,with an increasing modifying cation ratio. The morphologicalcharacterization through SEM showed that a higher contentof 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 ferro-magnetic behavior with variations in saturation and rema-nent magnetizations due to the influence of modifyingcations. The analysis revealed a correlation between thecationic charge and the magnetic and structural propertiesof the hydrotalcites, suggesting effective control over the mag-netic properties by manipulating the cationic charge in thesecomposite materials.