Impact of lanthanum doping on crystal structure and magnetic anisotropy of Mn-Zn soft nanoferrites

The synthesis of lanthanum (La) substituted Zn (Mn_0.6Zn_0.2La_0.2Fe₂O₄) and Fe (Mn_0.6Zn_0.4La_0.2Fe_1.8O₄) was performed using sol-gel auto-combustion techniques to investigate the effects of lanthanum doping on the structural and magnetic properties of Mn-Zn nanoferrites. X-ray diffraction and transmission electron microscopy confirmed the development of a single-phase spinel structure and a reduction in crystallite size (from 16 to 10.7 nm) with La substitution. Although saturation magnetization (M_s) decreased due to changes in cation distribution and magnetic interactions, La doping led to an increase in initial permeability. This enhancement was linked to changes in M_s and the magneto-crystalline anisotropy constant (K₁). The permeability loss factor (tan δ_µ) remained low (around 10^{- 2}) for the La-doped ferrites, indicating minimal energy loss at room temperature. These results suggest promising potential for advanced biomedical applications, in line with Sustainable Development Goals (SDGs). The sol-gel auto-combustion technique provides a scalable and environmentally friendly method for synthesizing these materials, supporting SDG targets related to responsible consumption and production (SDG 12).