Improved coercivity and considerable saturation magnetization of cobalt ferrite (CoFe2O4) nanoribbons synthesized by electrospinning

Cobalt ferrite (CoFe2O4) nanoribbons with high crystallinity and purity were synthesized by annealing the as-spun PVP/[Co(NO3)2+Fe(NO3)3] precursor nanoribbons at temperatures from 450 to 750 °C in air, and they were certified to have an improved coercivity (H c) and considerable saturation magnetization (M s). Although all the prepared CoFe2O4 nanoribbons presented an excellent ferromagnetism behavior at room temperature, their M s progressively increased with increasing annealing temperature but H c followed an opposite variation tendency. The maximum M s of about 80.3 emu g−1 of the nanoribbons annealed at 750 °C was basically equal to the bulk value, and the maximum H c of about 1802 Oe of the nanoribbons annealed at 450 °C, is larger than most of reported H c values of other one-dimensional CoFe2O4 nanostructures by far. It suggested that the magnetization reverse processes of the CoFe2O4 nanoribbons annealed at 450 and 550 °C were dominated by the coherent rotation model, while that of the CoFe2O4 nanoribbons annealed at 650 and 750 °C were dominated by the growth of a reverse magnetic domain.