Effect of Porous Structure on the Magnetic Properties of Ni_xMg_yZn_1−x-yFe₂O₄ Magnetic Materials

We deal with the preparation of NiMgZnFe^III−SO₄ layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFe^III−SO₄ LDHs to produce Ni_xMg_yZn_1−x-yFe₂O₄ ferrites that contain massive ZnO. Then the Ni_xMg_yZn_1−x-yFe₂O₄ ferrites are treated with NaOH solution to remove ZnO to produce the porous Ni_xMg_yZn_1−x-yFe₂O₄ magnetic material: when y=0, porous NiZnFe₂O₄ ferrite magnetic materials are obtained; when y≠0, porous NiMgZnFe₂O₄ ferrite magnetic materials are obtained. From analyses of these two ferrites, their pore−forming mechanism and comparison of their properties before and after they undergo the alkali treatment, we find that after being treated by the NaOH solution, NiZnFe₂O₄/ NiMgZnFe₂O₄ have better uniform-structure pores, which will greatly expand their pore volume, widen their application scope and improve their magnetic properties.