Fabrication and magnetic properties of electrospun zinc ferrite (ZnFe 2 O 4 ) nanofibres

The present paper describes the fabrication of zinc ferrite (ZnFe₂O₄) nanofibres by electrospinning method using a solution that contained polyvinyl pyrrolidone (PVP) and Zn and Fe nitrates as alternative metal sources. The as spun and calcined ZnFe₂O₄/PVP composite samples were characterised by thermogravimetric differential thermal analysis, X-ray diffraction, Fourier transform infrared and SEM respectively. After calcination of the as spun ZnFe₂O₄/PVP composite nanofibres (fibre size of 344 ± 76 nm in diameter) at 500, 600 and 700°C in air for 2 h, the nature of nanofibres was changed due to the reorganisation of the ZnFe₂O₄ structure at high temperature, and ZnFe₂O₄ nanofibres of 58–75 nm in diameter having well developed spinel structure were successfully obtained. The crystal structure and morphology of the nanofibres were influenced by the calcination temperature. The calcined ZnFe₂O₄ samples have a structure of packed particles or crystallites with crystallite sizes of 19, 20 and 26 nm for the samples calcined at 500, 600 and 700°C respectively. Room temperature magnetisation results showed a superparamagnetic behaviour of the ZnFe₂O₄ samples calcined at 500 and 600°C and a paramagnetic behaviour of the ZnFe₂O₄ samples calcined at 700°C. The specific magnetisation M_s values at 10 kOe are 2·34, 2·55 and 1·53 emu g^–1 for the samples of ZnFe₂O₄/PVP composite nanofibres calcined at 500, 600 and 700°C respectively.