Single-Step Solution-Combustion Synthesis of Magnetically Soft NiFe2O4 Nanopowders with Controllable Parameters

Аннотация

One-step solution-combustion synthesis with glycine as a fuel was used to obtain ferromagnetic nickel ferrite (NiFe₂O₄) spinel. According to EDX data, the elemental composition of all synthesized samples corresponded to NiFe₂O₄, while the XRD results showed the formation of phase-pure nickel ferrite spinel. NiFe₂O₄ nanopowders had a branched porous microstructure as established by SEM analysis. Variation in the Red/Ox ratio (glycine to nitrate ratio G/N = 0.4, 0.6, 0.8, 1.0, 1.2) was found to affect the average size of nickel ferrite crystallites (D) within the range 23–37 nm. The results of vibration magnetometry showed the ferromagnetic ordering in magnetic moments of NiFe₂O₄ nanopowders. The magnetic parameters of synthesized nickel ferrite—saturation magnetization M_s = 31–59 emu/g, remanent magnetization M_r = 3–13 emu/g, and coercive force H_c = 10–95 Oe—were found to depend on crystallite size D. The fact that the values of M_s, M_r, and H_c grow with increasing D opens up a way to synthesis of NiFe₂O₄ nanopowders with controllable magnetic parameters by simply varying the G/N ratio of starting solution.