Structural, dielectric, and multiferroic properties of Ta₂O₅-modified BiFeO₃–BaTiO₃–LaFeO₃ solid solutions

In this work, a series of Ta₂O₅-doped 0.675BiFeO₃–0.3BaTiO₃–0.025LaFeO₃−x mol% Ta₂O₅ (x = 0, 0.25, 0.50, 0.75, 1.0, 1.25) multiferroic ceramics were synthesized by solid-state reaction. The effects of Ta⁵⁺ doping on their phase structure, morphology, dielectric, ferroelectric, magnetic, and magnetoelectric properties were assessed. All samples were found to crystallize in perovskite structures, and the grain size was remarkably decreased by Ta⁵⁺ doping. Ta₂O₅ was beneficial to the dielectric properties, with the dielectric constant rising from 829 for undoped ceramic to 1149 for x = 1.25 at 100 Hz. The remnant polarization P_r and coercive field E_c decreased as x increased, indicating the worsening of ferroelectric behavior. In comparison, the ferromagnetism was evidently enhanced with increasing content of Ta₂O₅, and the remanent magnetization Mr peaked at 0.035 emu/g for x = 0.75. The magnetoelectric coefficient α_ME reached the maximum (418.68 mV/cm·Oe) for x = 0.25 at 200 Oe and 10⁵ Hz.