Tailoring energy storage performance in 0.9BaTiO3-0.1Bi(Mg2/3Ta1/3)O3 ceramic composites: A synergistic experimental and phase-field study on effects of dopant

Relaxor ferroelectrics (RFE) serve as superior alternatives to ferroelectrics (FE) for energy storage owing to their enhanced energy storage efficiency and thermal stability. This study combines experimental characterization and phase-field simulations to systematically investigate the effects of dopant distribution on the energy storage properties of RFEs. By analyzing the microstructure evolution and key performance metrics—including characteristic temperatures ( T f , T m , T B ), recoverable energy storage density ( W rec ), and dielectric constant ( ε r )—we establish a phase-field model incorporating diffusive compositional distribution of the dopant to reveal the underlying mechanisms of RFE behavior in 0.9BaTiO 3 -0.1Bi(Mg 2/3 Ta 1/3 )O 3 (0.9BT-0.1BMTa). Experimental results confirm frequency dispersion and characteristic relaxor behavior, while simulations reveal that dispersed BMTa concentrations enhance W rec stability on temperature at the expense of peak values, with optimal performance occurring between the dielectric maximum temperature ( T m ) and Burns temperature ( T B ). The local electric field is shown to moderately improve thermal stability but exerts less influence than compositional distribution. For practical energy storage applications , we propose design protocols: (1) prioritize concentrated dopant distributions if high W rec or fixed-temperature operation is required, and (2) adopt widely dispersed dopants for broad temperature-range stability. These findings provide a quantitative framework for tailoring perovskite-structured RFEs via compositional engineering, balancing performance metrics for targeted device specifications.