Magnetic/optical assessments of RFeO3 (R=La, Pr, Nd, and Sm) ceramics: An experimental and theoretical discernment

Experimental and Density Functional Theory (DFT) studies on the structural, magnetic and optical properties of rare-earth orthoferrites RFeO3 (R = La, Pr, Nd, and Sm) were performed. The synthesis was carried out via the Ethylenediaminetetraacetic acid (EDTA)-citrate method. All these perovskites exhibited orthorhombic crystal structures with a space group Pbnm, and their lattice parameters and unit cell volumes decreased as a function of the rare earth ionic radius, as it was expected. The microstructural analysis indicates that all the perovskites share similar textural properties. The magnetic characterization revealed a weak ferromagnetic behavior attributed to the canted antiferromagnetic Fe3+ sublattices, with the dominant magnetic configuration identified as the G-type. Super-exchange interactions between Fe3+-O-Fe3+, R3+-O-Fe3+, and R3+-O-R3+ couplings facilitated a long-range magnetic ordering. The optical characterization indicated d-d electronic transitions, and the perovskites were confirmed as semiconductors with a bandgap of approximately 2.1 eV. The calculation of the transition dipole moment demonstrates two significant aspects: the electronic transition is direct and allowed, and its enhancement is evident in the Sm sample. Overall, this study provides valuable insights into the crystal structure, magnetic properties and optical behavior of RFeO3 perovskites, synthesized via the EDTA-citrate method.