Pb/Bi-free Tungsten Bronze-Based Relaxor Ferroelectric Ceramics with Remarkable Energy Storage Performance

In this study, a Pb/Bi-free Sr2KNb5O15-based tungsten bronze relaxor ceramic system was developed for possible energy storage applications via the site engineering technology. The introduction of Ta at the Nb site enhanced the breakdown strength and relaxor nature of the Sr2KNb5O15 ceramic. An extremely high energy storage density (similar to 3.84 J/cm(3)) accompanied by a remarkable energy storage efficiency (similar to 93.2%) was obtained under an applied electric field of 410 kV/cm in the composition of Sr2KNb4.2Ta0.8O15. Meanwhile, the ceramic exhibited a relatively wide frequency stability (1-500 Hz) and thermal stability (30-120 degrees C) and displayed a remarkable fatigue endurance after 104 cycles. Even more surprisingly, the Sr2KNb4.2Ta0.8O15 ceramic processed excellent discharging performances with a short discharge time (tau(0.9) < 75 ns), a large discharge current density (1019 A/cm(2)), and an amazing power density (125.6 MW/cm(3)). The impressive performances demonstrated that the Sr2KNb4.2Ta0.8O15 tungsten bronze ceramic might be a potential Pb/Bi-free dielectric material for high-power pulse capacitor applications.

Automated summary

A Pb/Bi-free Sr2KNb5O15-based tungsten bronze relaxor ceramic system with enhanced breakdown strength and relaxor nature was developed by introducing Ta at the Nb site. The composition of Sr2KNb4.2Ta0.8O15 exhibited extremely high energy storage density and efficiency under an applied electric field, along with wide frequency and thermal stability, remarkable fatigue endurance, and excellent discharging performances. These impressive performances suggest that the Sr2KNb4.2Ta0.8O15 tungsten bronze ceramic could be a potential Pb/Bi-free dielectric material for high-power pulse capacitor applications.