The effect of anion on the magnetic properties of nanocrystalline NiO synthesized by homogeneous precipitation

The effect of using different anions (nitrate, chloride, sulfate, and acetate) during the precursor synthesis, by homogeneous precipitation, on the magnetic properties of the final product (nanocrystalline NiO), has been studied. The precursors and the oxide were characterized by various analytical techniques including powder X-ray diffraction, FT-IR spectroscopy, thermal gravimetry (TGA), and magnetic measurements. The synthesized NiO samples possess crystallite size in the range, similar to 2-6 nm, depending on the anion of the nickel salt. The nickel oxide nanoparticles exhibit superparamagnetic behavior. Acetate and sulfate anions lead to NiO with higher saturation magnetization (similar to 1.2-1.8 emu/g), while chloride and nitrate anions lead to NiO nanoparticles with lower saturation magnetization (similar to 0.1-0.4 emu/g) values. The observed magnetic behavior has been attributed to the size effect. (C) 2009 Elsevier B. V. All rights reserved.