Tailorable Electrical Materials by Simultaneous Maneuvering of <i>A</i> -Sites and <i>B</i> -Sites in BaTiO ₃

The study reports structural and electrical evolution in La³⁺/Mn³⁺ cosubstituted BaTiO₃, with compositions La_<i>x</i>Ba_1-<i>x</i>Mn_<i>x</i>Ti_1-<i>x</i>O₃ (<i>x</i> = 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 <i>P</i>-<i>E</i> 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_0.05Ba_0.95Mn_0.05Ti_0.95O₃. XPS confirmed mixed valence states of Mn (Mn²⁺/Mn³⁺) and O-vacancies which influenced structural and electrical behavior. Introduction of 2 mol % La³⁺/Mn³⁺ led to doubling of dielectric permittivity, K (∼1205), relative to BaTiO₃. This is attributed to plausible distortion in BaO₈/TiO₆ polyhedra caused by occupancy of the same lattice sites by ions of varying sizes and oxidation states. The composition La_0.05Ba_0.95Mn_0.05Ti_0.95O₃ showed an almost frequency-independent K (∼400) and low dielectric loss (0.05). La_<i>x</i>Ba_1-<i>x</i>Mn_<i>x</i>Ti_1-<i>x</i>O₃ (<i>x</i> ≥ 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_0.02Ba_0.98Mn_0.02Ti_0.98O₃ proposes a potential ferroelectric-photovoltaic material. These results establish La/Mn codoping in BaTiO₃ as an effective strategy to yield ferroelectrics, low-loss dielectrics, and conductors by composition-driven structural tailoring.