Structural engineering for excellent energy storage and photoluminescence properties in (Bi0.5Na0.5)TiO3 -based lead-free ferroelectrics ceramics

Lead-free ferroelectric ceramics show promising applications in environmentally friendly optoelectronic devices, yet conventional Bi 0.5 Na 0.5 TiO 3 -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 0.5 Na 0.5 TiO 3 -based ceramics on their energy storage and photoluminescence properties was systematically studied. It was found that the doping of BaTiO 3 and SrTiO 3 caused 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 0.5 TiO 3 -0.25BaTiO 3 with a high recoverable energy density of 3.73 J/cm 3 and an outstanding efficiency of 85.62 % under 350 kV/cm, while 0.75Bi (703/1500) Dy (47/1500) Na 0.5 TiO 3 -0.25SrTiO 3 exhibited strong photoluminescence properties, suggesting its potential as a yellow-green phosphor for warm white LEDs. Besides, SrTiO 3 doping enhanced crystal field symmetry to suppress thermal quenching via reduced phonon coupling, simultaneously improving Dy 3+ 6 H 15/2  →  4 I 13/2 transitions 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 0.5 Na 0.5 TiO 3 ceramics, thereby will be beneficial for advancing the development of high-performance multifunctional dielectric capacitors.