Quantitative analysis of various dn electronic configurations of transition metal ions using Tanabe Sugano diagrams in Bi1-xBaxFe1-yMnyO3 thin films

Bismuth ferrite (BFO) is a well-known multiferroic material that has many possible applications. In the present study, structural transformation in BFO is traced by the substitution and co-substitution of dopant. The influence of substitution on d-configuration is identified and an energy level diagram is constructed. Specifically, it exhibits a complex electronic structure that correlates well with the crystal structure. Modification in the electronic transitions of the system is analyzed using optical data within the framework of Tanabe-Sugano (TS) diagrams. The experimental ultraviolet and visible electromagnetic spectrum is analyzed with the aid of prediction of TS diagrams for d³, d⁴, d^5, and d⁶ configurations, for the extraction of Racah parameters, crystal field splitting energies, and nephelauxetic ratios. The vanishing of d-d transitions with the substitution of dopants is according to the TS diagrams. The Racah parameter and nephelauxetic ratio for all the co-substituted compositions are observed to increase with co-substitution. An increase in Racah parameters in co-substituted BFO thin films is related to the Ba-5d, Ba-5p, and Mn-3d states hybridization with O-2p states. This hybridization controls the influence of the ligands on the metal ion. This ligands-metal ion interaction also affects the interelectronic repulsion, Racah parameter, and nephelauxetic ratio.