Preparation And Magnetic Properties Of Anisotropic(sm,pr)CO₅Matrix Composite Particles

Nowadays, along with the progress of science and technology, magnetic materials areperforming more and more important impact in people,s life. This experiment have produced(Sm,Pr)Co₅/Fe,(Sm,Pr)Co₅/FeCo and (Sm,Pr)Co₅/Co core-shell like nanocomposite materialsby reduction FeCl₂, FeSO4and CoCl₂with NaBH4or N₂H₄.H₂O.The structure, morphologyand magnetism have been tested by means of X-Ray Diffraction (XRD), scanning electronmicroscope (SEM) and vibrating sample magnetometer (VSM).The saturation magnetization of soft magnetic materials Co, FeCo and Fe increases bydegrees, that is to say, bulk Fe highest(219.7emu/g) and Co lowest(161emu/g). The saturationmagnetization of (Sm,Pr)Co₅/Fe cladding by Fe particles is84emu/g, much greater than of(Sm,Pr)Co₅(60emu/g)which is used as matrix. But the degree of coupling in (Sm,Pr)Co₅/Feis weak due to aggregation of Fe nanoparticles, low area of contact in interface and easyoxidation. The saturation magnetization of (Sm,Pr)Co₅/FeCo is73.7emu/g, compared to(Sm,Pr)Co₅(50emu/g) before decorating with FeCo(40-70nm) particles. The unsatisfactorycoupling result should be owed to the large size of FeCo which exceed dimensions(d<10nm)require by ideal coupling between hard/soft phase. By contrast, the Co nanoparticles havebeen synthesized with mean particle sizes in therange of20–50nm and tightly attached on the2h ball milled (Sm,Pr)Co₅. The nanocomposite particles (Sm,Pr)Co₅/Co present [001]out-of-plane texture and improved magnetic properties, e.g., anenhanced remanentmagnetization of72emu/g for (Sm,Pr)Co₅/Co with a Hc of8.9kOe (10.8kOe for(Sm,Pr)Co₅). And66emu/g for (Sm,Pr)Co₅. Inaddition, by using the8h ball milled powders(much smaller than the2h ball milled powders) as the starting materials, Co nanoparticlescan also be successfully coated on the surface of the flakes(with a thickness of10–20nm andalength of0.5–1.5μm).