Multifunctional tuning of structural, dielectric, and magnetic properties of Ti-doped BaMnO₃ ceramics

BaMn_1−xTi_xO₃ (with x = 0.00, 0.25, 0.50, 0.75, 1.00) ceramics were prepared via conventional solid-state reaction method. Rietveld’s refined XRD patterns revealed the phase transition from pure hexagonal to rhombohedral to tetragonal as the Ti content is increased in the BaMnO₃ lattice. The FESEM images confirm the cuboid, flakes, angular, rod, and quasi-spherical grain morphology for BaMn_1−xTi_xO₃ at different concentrations of Ti ions, respectively. EDS spectra confirm each element according to their nominal compositions. Temperature-dependent dielectric spectra show two ferro phase transition peaks for 0.25 and 0.50 content of Ti ions, while the first transition peaks shifted below room temperature for x = 0.75 and 1.00. Complex impedance and modulus spectroscopy confirm the non-Debye-type relaxation in all the ceramics. The ac conductivity is observed to increase with increasing temperature, confirming the negative temperature coefficient resistance (NTCR) behavior of all the samples. Ti doping generates oxygen vacancies (V_o) and defects in the crystal lattice and leads to an increase in activation energy and hence temperature-dependent dielectric relaxation. The room-temperature ferromagnetism in Ti-doped BaMnO₃ can be related to bound magnetic polarons (BMPs).