Low-Temperature Synthesis and Characterization of Spinel Ferrite Powders

Nanoparticles of NiAlxFe2–xO4(x = 0; 0.1; 0.2; 0.3; 0.4, and 0.5) are synthesized by sol–gel method with auto-combustion. X-ray diffraction patterns confirm the single phase spinel structure of the samples produced. The scanning electron microscope images indicate that the particle size of the samples lies in a nanometer range. Synthesized in this manner, the powder has high crystallinity and good morphological homogeneity. It is observed that the grain size decreases from 46 to 18 nm as the nonmagnetic Al content increases. The lattice constant and radiodensity of ferrites depending on the content of the component x are determined. The structural and adsorption characteristics of the synthesized samples are determined by analyzing nitrogen sorption isotherms at 77 K. It is demonstrated that the samples produced are mesoporous because their pores are 2–5 nm in size. The thermal processes are investigated by thermal analysis and infrared spectroscopy. It is established that the nitrate-citrate gel burns automatically and then directly transforms into nanosized ferrite particles.