Microstructure and magnetic properties of electrospun one-dimensional Al3+-substituted SrFe12O19 nanofibers

SrAlxFe12−xO19 (x=0–3.0) nanofibers with diameters about 100 nm have been prepared by electrospinning and subsequent heat treatment. With Al3+ ion content ranging from 0 to 3.0, the lattice parameters decrease due to Fe3+ ions substituted by smaller Al3+ ions and the average grain size calculated by the Scherrerʹs equation reduces from 65 to 37 nm. The magnetization shows a continuous reduction with the Al content and its value measured at 77 K is higher than at room temperature, which can be explained by Blochʹs law. For the coercivity, its value initially increases, reaching a maximum value of 617 (298 K) and 547 kA m−1 (77 K) at x=2.0, and then reduces with the Al content further increase largely arising from the substituted Al3+ ion arrangement in different interstitial sites of the strontium ferrite unit cell.