Reinforcement of room temperature ferromagnetism in Ni2+-doped Aurivillius Bi4Ti3O12 nano-dumbbells

Applications for effective spin manipulation have recently made materials with high saturation magnetization desirable, which has improved performance and opened up new spintronics functionalities. The magnetic properties have been tailored in this work by doping the Bi₄Ti₃O₁₂ (BTO) lattice with Ni²⁺ of different contents. While pristine BTO has the orthorhombic structure according to XRD analysis, the BTO that has a higher Ni²⁺ content forms the hetero-interface with Bi₂Ti₂O₇ that is consistent with the TEM image. The TEM image of Bi₄Ti₃O₁₂-doped with 1% Ni²⁺ also reveals dumbbell morphology, with a small number of them exhibiting a deformation at one end. The presence of Ni incorporated into the Aurivillius-type Bi₄Ti₃O₁₂ lattice as Ni²⁺ ions is demonstrated by the X-ray photoelectron spectrum of 1% Ni-doped Bi₄Ti₃O₁₂. In comparison to pristine BTO, Raman measurements highlight the development of a stress-induced symmetry-breaking effect inside the 1% Ni²⁺-doped BTO symmetry, resulting in fewer modes. When the Ni²⁺ content in the Bi₄Ti₃O₁₂ lattice increases, the band gap decreases from 3.12 eV to 3.05 eV, as witnessed in the UV–Vis spectra, which also suggests that photo-absorption extends into the visible light spectrum. It’s important to note, in particular, that the BTO nano-dumbbells doped with 1% Ni exhibit strong RTFM because of their increased saturation magnetization, which also indicates their implications in the emerging field of spintronics as a result of band gap shrinkage.