Microstructure And Magnetic Properties Of Sm-Co/Tb(,Dy)-Fe-B Dual-Phase Nanowires

With the development of the technology,the demand for information storage is increasingly strong.The magnetic recording medium of rare-earth alloy nanowires has obvious vertical anisotropy,high coercivity and high remanence ratio,which makes ultra-high density magnetic storage possible.In this paper,Tb-Fe-B magnetic nanowires and nanotubes were prepared on the self-made anodic alumina oxide(AAO)templates by electrochemical deposition.On this basis,Tb-Dy-Fe-B magnetic nanowires were prepared by adding rare earth element Dy to the deposition solution.In addition,the Sm-Co/Tb-Fe-B dual-phase magnetic nanowire arrays were successfully prepared by alternating deposition.The phase composition,microscopic morphology,crystal structure,and magnetic properties of nanowires are characterized and analyzed by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),high-resolution transmission electron microscopy(HRTEM)and vibrating sample magnetometer(VSM).The SEM images exhibit that the as-deposited nanowires have high filling rate,smooth rod,highly ordered arranged,uniform diameter with 75 nm.Analysis of the XRD patterns shows that the deposited Tb-Fe-B nanowires and nanotubes are composed of Fe₃B phase,Tb B₆phase and a small amount of amorphous phase.After annealing at 600°C for 2h,the amorphous structure crystallizes into Fe₃Tb phase,Tb₂Fe₁₄B phase,and Tb B₆₆phase.The as-deposited Tb-Dy-Fe-B nanowires and the as-deposited Sm-Co/Tb-Fe-B dual-phase nanowires only have Fe₃B crystalline phase and amorphous phase.After annealing at600°C for 2 h,the amorphous phase is crystallized.The annealed Tb-Dy-Fe-B nanowires consist of Tb₂Fe₁₄B phase,Fe₃Tb phase,Dy₆Fe₂₃phase,Fe₃B phase,Dy B₆phase,and Dy Fe₃phase.The annealed Sm-Co/Tb-Fe-B dual-phase nanowires form Co₃Tb phase,Tb₂Fe₁₄B phase,Fe₃B phase,Tb B₆₆phase,Fe₇Sm phase,Sm₂Co₁₇phase and other crystalline phases.The phase composition of the three nanowires obtained from the HRTEM images by FFT is consistent with XRD patterns analysis.In addition,the dislocation structure was found in the microstructure of magnetic nanowires.In the microstructure of Tb-Dy-Fe-B magnetic nanowires,it is found that Fe₃Tb phase and Dy Fe₃phase have a coherent phase boundary.At the same time,the formation mechanism of the Tb-Fe-B nanotubes was illustrated.By comparing the magnetic properties of Tb-Fe-B nanoarrays,Tb-Dy-Fe-B nanowires and Sm-Co/Tb-Fe-B dual-phase nanowires with different Tb³⁺concentrations,it is found that the magnetic properties of Sm-Co/Tb-Fe-B dual-phase nanowires and Tb-Dy-Fe-B nanowires are both better than that of Tb-Fe-B nanoarrays.In addition,the magnetic property of Tb-Fe-B nanotubes is better than that of Tb-Fe-B nanowires at the same Tb³⁺concentration.When the concentration of Tb³⁺is 0.04 mol/L,the Sm-Co/Tb-Fe-B dual-phase nanowires have the best performance.The coercivity is 3210.61 Oe and the remanence ratio is 0.84.This discovery opens up the development field of magnetic recording medium materials,and more excellent perpendicular magnetic recording medium materials can be obtained through interaction of different rare earth elements or bidirectional coupling of soft and hard magnetic phases.