US EPA

2607933 

Journal Article 

Nanostructures and magnetic properties of cobalt ferrite (CoFe2O4) fabricated by electrospinning 

Sangmanee, M; Maensiri, S 

2009 

Yes 

Applied Physics A
ISSN: 0947-8396
EISSN: 1432-0630 

97 

1 

167-177 

10.1007/s00339-009-5256-5 

WOS:000269206600023 

This paper describes the fabrication of cobalt ferrite (CoFe2O4) nanostructures (in the form of nanofibers and nanoparticles) by the electrospinning method using a solution that contained poly(vinyl pyrrolidone) (PVP) and cheap Co and Fe nitrates as metal sources. The as-spun and calcined CoFe2O4/PVP composite samples were characterized by TG-DTA, X-ray diffraction, FT-IR, SEM and TEM, respectively. After calcination of the as-spun CoFe2O4/PVP composite nanofibers (fiber size of 320 +/- 48 nm in diameter) at 500, 600, and 800A degrees C in air for 3 h with different heating rates of 5 or 20A degrees C/min, either NiFe2O4 nanofibers of similar to 10-200 nm in diameter or nanoparticles with particle sizes of similar to 50-400 nm having a well-developed spinel structure were successfully obtained. The crystal structure and morphology of the nanofibers were influenced by the calcination temperature and heating rate. A faster heating rate allowed for a rapid removal of the PVP matrix and resulted in a complete change from fibrous structure to particle in the calcined CoFe2O4/PVP composite nanofibers. Room temperature magnetization results showed a ferromagnetic behavior of the calcined CoFe2O4/PVP composite nanofibers, having their hysteresis loops in the field range of +/- 4500 and 3000 Oe for the samples calcined respectively with heating rates of 5 and 20A degrees C/min. The values of the specific magnetization (M (s)) at 10 kOe, remnant magnetization (M (r)), M (r)/M (s) ratio, and coercive forces (H (c)) are obtained from hysteresis loops. It was found that the values of M (s), M (r), M (r)/M (s), and H (c) depended strongly on morphology of the CoFe2O4 nanostructures.