Preparation and magnetic properties of lanthanum- and cobalt-codoped M-type strontium ferrite nanofibres

Sr 1x La x Fe 12x Co x O 19 (x 0.12) nanofibres have been successfully prepared by sol-gel method, electrospinning and subsequent heat treatment.The prepared nanofibres were characterised via X-ray diffraction (XRD), transmission electron micrograph (TEM) and superconducting quantum interference device (SQUID).The XRD revealed that the crystal structure of samples was hexagonal magnetoplumbite structure at calcination temperature from 900 C to 1100 C. The TEM showed that the ferrite nanofibres had a smooth morphology and a bamboo joint structure, and the diameter of nanofibres increased with the increase of sintering temperature.The SQUID revealed that there were some intriguing changes in magnetic properties with the variation of sintering temperature or altering calcination time, and the optimised magnetic property of samples was M s 70.76 emu/g, M r 36.35 emu/g and H c 6.26 kOe at 950 C for 2 h, the corresponding grain size was 39.30 nm.Meanwhile, the nanofibres display more significant improvements in the magnetic properties than the nanoparticles obtained by the sol-gel process, which was probably due to the anisotropic morphology and the cylindrical magnetic domain of ferrite nanofibres.