Structural engineering for excellent energy storage and photoluminescence properties in (Bi_0.5Na_0.5)TiO₃-based lead-free ferroelectrics ceramics

Lead-free ferroelectric ceramics show promising applications in environmentally friendly optoelectronic devices, yet conventional Bi_0.5Na_0.5TiO₃-based materials face challenges in achieving balanced enhancement of energy storage density and photoluminescence properties. In this study, the influence mechanism of the structural evolution of Bi_0.5Na_0.5TiO₃-based ceramics on their energy storage and photoluminescence properties was systematically studied. It was found that the doping of BaTiO₃and SrTiO₃caused local structural distortion and oxygen octahedral tilt, and the introduction of larger radius ions in A-site significantly refined grain size and improved breakdown electric field, endowing 0.75Bi_(703/1500)Dy_(47/1500)Na_0.5TiO₃-0.25BaTiO₃with a high recoverable energy density of 3.73 J/cm³and an outstanding efficiency of 85.62 % under 350 kV/cm, while 0.75Bi_(703/1500)Dy_(47/1500)Na_0.5TiO₃-0.25SrTiO₃exhibited strong photoluminescence properties, suggesting its potential as a yellow-green phosphor for warm white LEDs. Besides, SrTiO₃doping enhanced crystal field symmetry to suppress thermal quenching via reduced phonon coupling, simultaneously improving Dy³⁺⁶H_15/2 → ⁴I_13/2transitions through optimized parity-forbidden relaxation. These findings elucidate the pivotal role of structural engineering strategies in tailoring the energy storage and photoluminescence properties of Bi_0.5Na_0.5TiO₃ceramics, thereby will be beneficial for advancing the development of high-performance multifunctional dielectric capacitors.