Effect of B-site Co substitution on the structure and magnetic properties of nanocrystalline neodymium orthoferrite synthesized by auto-combustion

Samples of cobalt-doped neodymium orthoferrite compounds, NdCoxFe1-xO3 (0.0 ≤ x ≤ 0.5) were synthesized via glycine auto-combustion between 250 – 300 °C and calcined at 500 °C for two hours. X-ray diffraction showed that all compounds had an orthorhombic perovskite structure with space group Pbnm. Increasing cobalt doping gradually reduced the lattice parameters and contracted the unit cell volume. Both X-ray diffraction and Scanning Electron Microscopy showed that the particles were spherical and in the nano-sized range (19 – 52 nm). Vibrating sample magnetometry indicated that nonmagnetic Co3+ ions produced magnetic vacancies which led to a decrease in magnetization. Results also showed that coercive fields of the doped samples were lower than the undoped and generally increased with cobalt doping, attaining a maximum value of 601 Oe for NdCo0.4Fe0.6O3. By introducing magnetic vacancies, these compounds could serve as prototypes for tuning the properties of magnetic materials (ferromagnetic and antiferromagnetic) with potential applications in data storage, logic gates, switches, and sensors.