Morphological and Magnetic Characteristics of Strontium Ferrite Micro- and Nanofibers

Abstract

Strontium ferrite micro- and nanofibers have been prepared by the sol-gel process and the electrospinning with diameters about 1 μm and 100 nm, respectively. Single phase strontium ferrite fibers are formed after calcined at 750 °C for 2 hours for both the sol-gel and electrospinning processes. These strontium ferrite fibers are fabricated of nanosized particles with a hexagonal plate-like morphology, which grow with the calcination temperature. The microfiber cross-section contains multi-nanoparticles whilst the nanofiber with a necklace-like morphology is linked by nanoparticles at the calcination temperature range from 850 to 1050 °C. The magnetic properties of strontium ferrite fibers are mainly influenced by the grain size and fiber diameter. Both the strontium ferrite micro- and nanofibers calcined at 900°C for 2 hours are fabricated from single-domain grains around 56 nm and exhibit the specific saturation magnetization of 60.8 A•m 2 •kg -1 (microfibers) and 59.9 A•m 2 •kg -1 (nanofibers) and coercivity of 361.9 kA•m -1 (micronfibers) and 523.6 kA•m -1 (nanofibers). The coercivity difference between the micro- and nanofibers can be attributed to the different shape anisotropy energies arising from various magnetization reversal behaviors for the micro- and nanofibers.