Preparation and characterisation of magnetically ordered columnar structures of barium ferrite particles

摘要

In this study, we report on the columnar structures of barium ferrite particles that were prepared from water suspensions by applying a magnetic field during drying. Commercial barium ferrite (BaFe_(12)O_(19)) monodomain particles were used, and the surfaces of the particles were treated with an organic surfactant to reduce their agglomeration. The columnar structures were obtained by drying the water suspensions of BaFe_(12)O_(19) particles on Al_2O_3 substrates under an applied magnetic field of 1 T. After the degradation of the organic components, the samples were sintered at 1350℃. X-ray powder diffraction, scanning electron microscopy and magnetic measurements were used to characterise the samples. When the magnetic field was applied perpendicularly to the sample plane, the as-deposited sample exhibited a higher coercivity (H_c=5434 Oe) and a higher squareness ratio (SQR=0.76) than the sintered sample (H_c=625 Oe, SQR=0.58). However, the sintered sample showed a higher anisotropy of the magnetic behaviour than the as-deposited sample.