Tailorable Electrical Materials by Simultaneous Maneuvering of A -Sites and B -Sites in BaTiO 3

The study reports structural and electrical evolution in La 3+ /Mn 3+ cosubstituted BaTiO 3, with compositions La x Ba 1– x Mn x Ti 1– x O 3 ( x = 0.00–0.50) in search of lead-free energy storage materials. Solid-state synthesized samples were thoroughly characterized by XRD, Raman spectroscopy, XPS, SEM, AC-impedance, and P – E measurements. Structural analysis revealed a tetragonal-to-rhombohedral (T to R) phase transition with increasing substitution, accompanied by lattice distortion and reduced tetragonality. Raman spectroscopy could clearly delineate R-type modes in otherwise single-phasic (T) La 0.05 Ba 0.95 Mn 0.05 Ti 0.95 O 3 . XPS confirmed mixed valence states of Mn (Mn 2+ /Mn 3+ ) and O-vacancies which influenced structural and electrical behavior. Introduction of 2 mol % La 3+ /Mn 3+ led to doubling of dielectric permittivity, K (∼1205), relative to BaTiO 3 . This is attributed to plausible distortion in BaO 8 /TiO 6 polyhedra caused by occupancy of the same lattice sites by ions of varying sizes and oxidation states. The composition La 0.05 Ba 0.95 Mn 0.05 Ti 0.95 O 3 showed an almost frequency-independent K (∼400) and low dielectric loss (0.05). La x Ba 1– x Mn x Ti 1– x O 3 ( x ≥ 0.1) yielded lossy, conduction-dominated behavior consistent with defect-facilitated ion transport. Simultaneous occurrence of ferroelectricity and visible band gap (2.23 eV) in La 0.02 Ba 0.98 Mn 0.02 Ti 0.98 O 3 proposes a potential ferroelectric-photovoltaic material. These results establish La/Mn codoping in BaTiO 3 as an effective strategy to yield ferroelectrics, low-loss dielectrics, and conductors by composition-driven structural tailoring.