Enhanced Energy Storage and Thermal-Frequency Stability in Lead-Free Relaxor Ceramics through Single-Element Substitution: A Landau Perspective

This paper presents a straightforward and effective strategy for achieving superior energy storage properties in lead-free dielectric ceramics using a single-element modification approach. Dielectric capacitors are widely used for energy storage applications; however, strontium bismuth titanate (SBT) remains relatively unexplored. In this study, we present the energy storage characteristics and underlying mechanism of relaxor ferroelectric SBT using Landau theory. Sr0.7Bi0.2TiO3 (SR 0.70) and Sr0.85Bi0.10TiO3 (SR 0.85) exhibit a tilted hysteresis loop demonstrating high discharge density. We designed systems to retain the cubic structure while maintaining structural stability without significant distortions. Our findings reveal that SR 0.85 ceramics exhibit exceptional frequency stability, a high dielectric constant, and significantly reduced dielectric loss. At an applied electric field of 227 kV/cm, the SR 0.85 ceramics attain a high energy storage density of 2.62 J/cm3, demonstrating their potential as advanced dielectric materials for energy storage technologies as compared to binary and ternary systems. The composition SR 0.85 exhibited outstanding thermal stability over a temperature range of 40–100 °C and maintained consistent performance across a broad frequency spectrum (1–1000 Hz). To further elucidate the underlying mechanisms that contribute to their superior energy storage performance, we correlated our experimental results with Landau’s theory. This analysis provides insights into the structural and dynamic factors for the utilization of high-performance single-element engineered lead-free systems for ultrahigh-energy storage applications that require miniaturization and integration in advanced pulse power systems.