Structural, Magnetic, and Catalytic Evaluation of Spinel Co, Ni, and Co–Ni Ferrite Nanoparticles Fabricated by Low-Temperature Solution Combustion Process

[Image: see text] Here, we present the low-temperature (∼600 °C) solution combustion method for the fabrication of CoFe(2)O(4), NiFe(2)O(4), and Co(0.5)Ni(0.5)Fe(2)O(4) nanoparticles (NPs) of 12–64 nm range in pure cubic spinel structure, by adjusting the oxidant (nitrate ions)/reductant (glycine) ratio in the reaction mixture. Although nitrate ions/glycine (N/G) ratios of 3 and 6 were used for the synthesis, phase-pure NPs could be obtained only for the N/G ratio of 6. For the N/G ratio 3, certain amount of Ni(2+) cations was reduced to metallic nickel. The NH(3) gas generated during the thermal decomposition of the amino acid (glycine, H(2)NCH(2)COOH) induced the reduction reaction. X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy techniques were utilized to characterize the synthesized materials. XRD analyses of the samples indicate that the Co(0.5)Ni(0.5)Fe(2)O(4) NPs have lattice parameter larger than that of NiFe(2)O(4), but smaller than that of CoFe(2)O(4) NPs. Although the saturation magnetization (M(s)) of Co(0.5)Ni(0.5)Fe(2)O(4) NPs lies in between the saturation magnetization values of CoFe(2)O(4) and NiFe(2)O(4) NPs, high coercivity (H(c), 875 Oe) of the NPs indicate their hard ferromagnetic behavior. Catalytic behavior of the fabricated spinel NPs revealed that the samples containing metallic Ni are active catalysts for the degradation of 4-nitrophenol in aqueous medium.