Fabrication and magnetic properties of Tb–Fe–B nanotubes prepared by electrochemical deposition

Tb–Fe–B magnetic nanotubes were firstly prepared via direct current (DC) electrochemical deposition method in anodic aluminum oxide (AAO) templates, and its formation mechanism was illustrated. Scanning electron microscopy (SEM) analyses showed that the Tb, Fe, and B elements were deposited into the nanotubes successfully. X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) were performed to investigate the morphology, micro-crystal structure, and magnetic properties of the ternary system Tb–Fe–B nanotubes at different solution concentrations. The results indicated that the nanotubes have the same one-dimensional structure as nanowires and the direction of the axis was easy to be magnetized. The as-deposited nanotubes consisted of soft magnetic phases (Fe₃B and TbB₆) and amorphous phase, which exhibited soft magnetic properties. After annealing at 600 °C for 2 h, the hard magnetic phases of Fe₃Tb and Tb₂Fe₁₄B appeared and the nanotubes transformed from an incomplete crystalline state to a complete crystalline state with a larger diameter. Due to the exchange coupling between hard and soft magnetic phases, Tb–Fe–B nanotubes obtained good hard magnetic properties with an improved coercivity. When the concentration of Tb ion is 0.04 mol/L, the relative intensity of the diffraction peaks and coercivity is the largest. Therefore, Tb–Fe–B rare-earth alloy nanotubes would be one promising magnetic storage and recording material.