Giant Electric Energy Density in Epitaxial Lead‐Free Thin Films with Coexistence of Ferroelectrics and Antiferroelectrics

Ferroelectrics/antiferroelectrics with high dielectric breakdown strength have the potential to store a great amount of electrical energy, attractive for many modern applications in electronic devices and systems. Here, it is demonstrated that a giant electric energy density (154 J cm−3, three times the highest value of lead-based systems and five times the value of the best dielectric/ferroelectric polymer), together with the excellent fatigue-free property, good thermal stability, and high efficiency, is realized in pulsed laser deposited (Bi1/2Na1/2)0.9118La0.02Ba0.0582(Ti0.97Zr0.03)O3 (BNLBTZ) epitaxial lead-free relaxor thin films with the coexistence of ferroelectric (FE) and antiferroelectric (AFE) phases. This is endowed by high epitaxial quality, great relaxor dispersion, and the coexistence of the FE/AFE phases near the morphotropic phase boundary. The giant energy storage effect of the BNLBTZ lead-free relaxor thin films may make a great impact on the modern energy storage technology.