Low temperature relaxor, polarization dynamics and energy storage properties of Ca_0.28Ba_0.72Nb₂O₆ tungsten bronze ceramics

The development of modern electronic devices requires dielectrics with high energy storage density, high power density and excellent working stability as the dielectric layer of multilayer ceramic capacitors. Herein, Ca_0.28Ba_0.72Nb₂O₆-based tungsten bronze ceramics doped by ions with various radii were prepared, and the energy storage performance was improved by adjusting the relaxor behavior. Rare double relaxor behavior was confirmed based on macroscopic phenomenological model and characterization of domain structure, and the low-temperature relaxor behavior was found to be sensitive to the in-plane polarization displacement disorder of Nb2 sites. Meanwhile, a significantly improved energy storage performance was obtained: W_re ∼ 2.59 J/cm³, η ∼ 85.3 %, P_D ∼ 130.78 MW/cm³. The excellent temperature stability of the energy storage performance is explained by the polarization reversal dynamics via Vopsaroiu model. This work highlights the potential of tungsten bronze as energy storage devices, and provides an additional feasible paradigm of pulse power capacitors with excellent thermal stability.