Synthesis of NiFe2O4 nanowires with NiO nanosheet as precursor via a topochemical solid state method

Abstract

Large scale NiFe2O4 nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe2O4 annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Fe– ions into NiFe2O4 nanowires. In the beginning stage of synthesizing process, the shape of NiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400 °C to 600 °C. At last they transformed into nanoparticles from 700 °C to 1000 °C. Thus, the optimized annealing temperature was selected as 600 °C because the NiFe2O4 obtained at 600 °C(N600) exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m2/kg and the lowest coercivity(Hc) of 8914 A/m.