High-efficiency energy storage and electric field-driven photoluminescence modulation in Sm/Bi-codoped SrTiO₃...

SrTiO₃ ceramic, a canonical linear dielectric, is reowned for its high energy storage efficiency (η), a sequence of its low dielectric loss and superior breakdown strength. However, its inherently low maximum polarization severely limits the achievable recoverable energy density (W_rec). In this study, a superparaelectric state featuring polymorphic polar nanoregions was engineered within the (Sr_1-1.5xBi_x-0.005Sm_0.005)TiO₃ system through deliberate introduction of local heterogeneity and structural distortion. This approach yielded a remarkable W_rec of 6.71 J/cm³ coupled with an impressive η of 90.36% under a high electric field of 600 kV/cm. First-principles calculations reveal that the enhancement in energy storage performance with increasing Bi³⁺ content stems from improved polarization, driven by the strengthened hybridization between O 2p and Bi 6s states. Additionally, the incorporation of Sm³⁺ ions endows the ceramics with excellent luminescent properties, notably a novel electric field-driven photoluminescence modulation effect, thereby significantly broadening their applications potential in optoelectronic devices. This work not only offers new insights into the design of high-performance dielectric energy storage materials but also paves the way for development of multifunctional ceramic capacitors.