The Research On The Preparation And Magnetic Properties Of Doped M-type Strontium Ferrite Nanofibers

Due to a high length-diameter ratio, anisotropy characteristics and large surface-to-volume ratio, nanofibres exhibited excellent performance, and it has been explored as a focus in numerous relative fields; At present, the method of preparation nanofibres was adopted respectively by drawing, Template Route, Hydrothermal, electrospinning and so on. Among these techniques, electrospinning technology has been widely adopted due to its simple preparation, versatility in a variety of polymeric fibers and producing fibers with the submicron range consistently, but it is difficult to achieve by other technologies. In this paper, the electrospun setup was improved, the results exhibit some amusing alteration in structure, morphology and magnetic properties.Polyethylene pyrrole (PVP) was used as spinning improver and metal nitrate as precursors, the composite nanofibres have been synthesized by sol-gel based on electrospinning, and the high-purity M-type strontium ferrites nanofibers was prepared via calcining the as-spun nanofibers. The samples were characterized by SEM, XRD, TEM, FITR and SQUID. The results revealed the composite nanofibres has relatively smooth surface, degree of alignment and a rather uniform diameter around200nm; the resultand nanofibres with uniform diameter is around50-100nm, the over a length of several meters, and it’s has very smooth surface, bamboo joint-like morphology. In this paper, the effects of the concentration of PVP, applied voltage and the solidification distance on morphology of electrospun fibers were investigated in detail; at room temperature, the optimal experimental parameters were determined:the concentration of PVP was18wt.%, the spinning voltage was18KV, and the solidification distance was13cm.the magnetic properties of mono-doping strontium ferrite(La,Ce.Co) were measured by SQUID, the results indicate that the process of annealing temperature being at950℃will obtain the best magnetic properties, Ms and Mr were improved respectively, the He of mono-doped strontium ferrites nanofibers with La(or Ce) were improved obviously, and the He of mono-doped strontium ferrites nanofibers with Co be diminished obviously. The substituted strontium ferrites nanofibres exhibited better magnetic properties than the corresponding nanoparticles obtained by the sol-gel processing. The magnetic properties of La-Co codoped strontium ferrites nanofibres greatly was improved,At present, the experimental parameters with electrospinning process were optimized for improving coercive force; meanwhile, the application of M-type strontium ferrites nanofibres was extended in high density vertical recording materials, micro-nano-scale electronic devices, microwave materials and so on in future. This study provides basis for studying properties and applications with the M-type strontium ferrites nanofibres in this area.