The elucidation of the alteration properties of BiFeO₃ doped (K_0.5Na_0.5)NbO₃ through local structure investigation

The alteration properties of BiFeO₃ doped (K_0.5Na_0.5)NbO₃ (KNN–BF) were investigated and focused on elucidating the origin of its modification. The crystal structure to have transformed from the initial orthorhombic to tetragonal shape at dopant amount x ≥ 0.025. Moreover, the XANES Fe K-edge analysis revealed the quadrupole transition 1s→3d, dipole transition 1s→4p, and edge energy E₀ of samples were higher than those of Fe₂O₃ after which the oxidation state of Fe was found to be a mixture of 3+ and 4+. The defects, however, affected the properties by producing relaxor due to the polar nanoregions (PNRs) besides the presence of lattice dipole. Furthermore, the KNN was altered to ferromagnetic possessing Ms up to 0.0076 emu g⁻¹ for x = 0.075 originating from the unpaired electron of Fe ions which was influenced by the interaction Fe³⁺-O^2--Fe⁴⁺ and Nb⁵⁺-V_O^••-Fe^3+/4+ in the B–O–B octahedron chain.