Effect of Preparation Conditions on the Structure and Magnetic Properties of Metal-Doped Magnesium Ferrites Synthesized From Laterite Leaching Solutions

Abstract

In this paper, metal-doped magnesium ferrites (MgFe2O4) were synthesized from laterite leaching solutions using a coprecipitation-calcination method. The as-synthesized samples were characterized by x-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), and physical property measurement system (PPMS) to determine the structure and magnetic properties. The effects of preparation conditions including precipitant reagents and metal ion concentrations in the laterite leaching solutions on the as-prepared spinel ferrites were investigated systematically. It is indicated that Ni–Co–Mn-doped MgFe2O4 and Mn–Al–Cr-doped MgFe2O4 could be synthesized from laterite leaching solutions by using sodium hydroxide (NaOH) and ammonia solution (NH3⋅H2O) as precipitant reagent, respectively. By adjusting the metal ion concentrations in the laterite leaching solutions, Ni–Co–Mn-doped MgFe2O4 with different substitution contents were obtained. With the Ni and Mn substitution content increasing, the lattice constant and average grain size decreased, while x-ray density increased correspondingly. Magnetic property tests indicated that all the as-prepared samples exhibited typical ferrimagnetic behavior at room temperature, and the saturation magnetization (Ms) depended on the Ni, Co, and Mn substitution content. Specifically, the Ms and Hc values of the as-prepared metal-doped MgFe2O4 sample with optimum substitution content of 0.185 could reach 33.22 emu g−1 and 53 Oe, respectively.