Simultaneously achieving large energy storage density and high efficiency in the optimized Sr2NaNb5O15 system with excellent temperature stability at a low electric field

Lead-free capacitors operating at low electric fields with high-energy density and high efficiency are critical for advanced electronic systems and innovative pulsed power applications. In this work, single tetragonal phase dielectric ceramics with high-energy storage density and high efficiency are prepared using the solid-state method. The co-substitution of Ba2+, Sm3+, and Mn4+ on the Sr2NaNb5O15 substrate enhances low-temperature relaxation behavior and polarization modulation due to order/disorder distribution and polar nanoregions (PNRs) in the structural distortion system. Ferroelectric tests revealed that the optimized Sr1.83Ba0.16Sm0.01NaMn0.01Nb4.99O15 tungsten bronze system has large energy storage density (Wrec = 4.432 J cm−3) and high efficiency (η = 84.3 %) at a low electric field (250 kV cm−1). In addition, the temperature-dependent permittivity results for the Sr1.82Ba0.165Sm0.015NaMn0.015Nb4.985O15 and Sr1.81Ba0.17Sm0.02NaMn0.02Nb4.98O15 ceramic samples demonstrated that they are X9R capacitor-compatible. Finally, Sr1.83Ba0.16Sm0.01NaMn0.01Nb4.99O15 has a current density (CD) of ∼797.77 A cm−2 and power density (PD) of ∼87.75 MW cm−3 with a very fast discharge time (t0.9 < 60 ns). It is worthy to note that all the components display excellent temperature stability (ΔWdis < 10 %) in the over-damping test. Thus, this work provides an avenue to obtain dielectric ceramic materials with potential application value in innovative pulse power components.