Preparation And Magnetic Properties Of M Type Ferrite Hollow Fibres

The M type ferrite follow fibres are a novel kind of ceramic fibrous materials. These fibers can be used in high-tech and national deference fields because of its excellent refractory, corrosion resistant, inoxidizable and electromagnetic absorbing performances.For the preparation of M type ferrite follow fibres, the Present techniques show some disadvantages, e.g., the morphology and the structure of the resulting nanocrystals are not easy to control, and it is difficult to produce high-purity nanocrystals in large quantities. While here we proposed a novel method for the preparation of M type ferrite follow fibres by the organic gel-precursor transformation method using citric acid and metal salts as raw materials. It featured in simplicity, low temperature, good controllability and high yield.The research focused on the preparation of the M-type strontium ferrite hollow fibres by the organic gel-precursor of citric acid and metal salts. The effect of the synthesis parameters on the formation and transformation of the M-type strontium ferrite hollow fibres were investigated in detail. The morphology, structure and particular properties of the product were characterized via FTIR,TG/DSC,XRD,SEM and VSM measurements, and the relationship between them and synthesis parameters were studied to realize the controllable preparation of the product. The research will provide a novel strategy for the development of various ceramic nanomaterials.The results show that The gel spinnability is related with the chemical composition and pH value. The gel exhibits an appropriate spinning performance when the molar ratio of citric acid to the total metal ions is 1.5:1 and the pH value is around 4.2. The M-type ferrite hollow fibers obtained are characterized with a high aspect ratio, thin diameters and a ratio of the hollow diameter to the fiber diameter being about 1/2 after heat treatment. The fibers are composed of nanoparticles with a hexagonal plate morphology and an average particle size of about several hundred nanometers.At room temperatures, the saturation magnetization and coercivity of the BaM and SrM ferrite hollow fibers obtained at calcination temperature of 950℃and 1100℃are 52.84 A·M²Â·kg^-1 467.19 kA·m^-1 and 53.54 A·m²Â·kg^-1 386.96 kA·m^-1, respectively. This M-type ferrite hollow fibers possess a shape anisotropy characteristic and the coercivity for the aligned hollow fibers parallel and parpendicular to the applied field is correspondingly 390.72.66 kA·m^-1, 359.69 kA·m^-1.