Structural and Magnetic Tuning of LaFeO3 Orthoferrite Substituted Different Rare Earth Elements to Optimize Their Technological Applications

Lanthanum partially substituted rare earth (RE) elements to form RE0.7La0.3FeO3; RE = Ce, Pr, Nd, Sm and Gd) nanoparticles. They were synthesized using the citrate-nitrate auto-combustion method. The crystal structure and microstructure were refined by applying Rietveld profile refinements using the Maud Program. The morphology, magnetic and optical properties of the inspected samples have been explored using HRTEM, VSM, and UV-Vis diffuse reflectance, respectively. The prepared-samples distortion increases as the substituted RE ionic radius decreases. Iron spins of RE orthoferrite samples are known to be ordered Anti-ferromagnetically (AFM). They also possess weak ferromagnetism due to the Dzyaloshinskii-Moriya interaction. This feeble ferromagnetism is reflected in their soft behavior, whereas Sm0.7La0.3FeO3 sample exhibits the butterfly shape hysteresis loop. The remnant magnetization, saturation magnetization, and coercivity are relatively small, but sometimes impressively, enhanced through Lanthanum-rare-earth substitution. Introducing rare earth ions into LaFeO3 decreases the Fe-O-Fe angle and the consequent reduction of the super exchange interaction. In particular, the coercivity of Sm0.7La0.3FeO3 is remarkably improved relative to the parent sample. It has the largest coercivity of all the prepared nanoparticles. Due to the aforementioned substitution, a slight reflectance edge red shift is observed in the spectra. The relation between the magnetic properties of the investigated samples and the ionic radii of RE was investigated and discussed. The experimental results of this work can provide fundamental support for the research and development of multiferroic materials.