High energy storage in tetragonal tungsten bronze ceramics engineered via superparaelectric state

Dielectric energy storage ceramics are critical components in advanced pulsed-power systems. Recently, ceramics with tetragonal tungsten bronze (TTB) structure have gained considerable interest owing to their freedom from volatile elements, which is a distinct advantage over many other widely studied energy storage ceramics. Nevertheless, achieving a simpler composition while maintaining a well-balanced enhancement in energy storage performance remains challenging. In this work, single La3+ ion was introduced into Sr0.6Ba0.4Nb2O6 ceramics, which induces a superparaelectric state at room temperature and effectively lowers the energy barrier for polarization switching. As a result, the obtained ceramic with a simple composition exhibits a high recoverable energy density of 3.48 J/cm3 and an ultrahigh efficiency of 95.4%, along with a notable figure of merit of 75.7. Moreover, the optimized composition demonstrates excellent frequency stability (1–200 Hz) and temperature stability (25–150 °C). This work proposes a feasible strategy for designing high-performance TTB energy storage ceramics, demonstrating the great potential of TTB ceramics in advanced energy storage applications.