Formation and magnetic properties of M-Sr ferrite hollow fibers via organic gel-precursor transformation process

The M-Sr ferrite hollow fibers have been successfully prepared by the organic gel-precursor transformation process. The phase formation process of M-Sr ferrite is analyzed by FTIR, XRD and consists of the gel-precursor thermal decomposition and the subsequent ferrite phase formation from strontium oxide and iron oxide. The M-Sr ferrite hollow fibers obtained are characterized with SEM and XRD, and show a high aspect ratio, fine diameters around 4 mu m and a ratio of the hollow diameter to the fiber diameter being about 1/2. The optimized M-Sr ferrite hollow fibers are composed of nanograins with a hexagonal plate morphology. Magnetic properties are measured with VSM under a maximum applied of 1194 kA m(-1). The M-Sr ferrite hollow fibers formed at 1100 degrees C for 2 h with the specific saturation magnetization of 53.5 A m(2) kg(-1) possess a shape anisotropy characteristic and the coercivity for the aligned hollow fibers parallel and perpendicular to the applied field is correspondingly 385 and 357 kA m-1. (C) 2009 Elsevier B.V. All rights reserved.