Abstract
Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (Wrec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which {rm{B}}{{rm{a}}_{0.105}}{rm{N}}{{rm{a}}_{0.325}}{rm{S}}{{rm{r}}_{0.245 - 1.5x}}{_{0.5x}}{rm{B}}{{rm{i}}_{0.325 + x}}{rm{Ti}}{{rm{O}}_3} ({rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}}, x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} ceramics are prepared by using pressureless solid-state sintering and achieve large Wrec (1.8 J/cm3) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm3 is super high as compared to all other Wrec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40–350 °C is also obtained in {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (Pr) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi0.5Na0.5TiO3 (BNT)-based ceramics with high Wrec and high-temperature stability.
Highlights
Dielectric capacitor is an indispensable component in contemporary electronic devices, which fulfills different functions such as direct current blocking, coupling, filtering, and pulse discharge [1,2,3]
Considering the complicated working environment, especially high temperatures (150–200 °C, even up to 300 °C), ceramic dielectrics would be more suitable for energy storage candidates than other polymer materials [4]
Ceramics possess a relatively high Wrec (> 1.5 J/cm3), together with a high (> 70%) under relatively low electric field (< 160 kV/cm), demonstrating that it is potential to obtain both high Wrec and, which should be a promising candidate for power ceramic capacitor application
Summary
Dielectric capacitor is an indispensable component in contemporary electronic devices, which fulfills different functions such as direct current blocking, coupling, filtering, and pulse discharge [1,2,3]. Considering the complicated working environment, especially high temperatures (150–200 °C, even up to 300 °C), ceramic dielectrics would be more suitable for energy storage candidates than other polymer materials [4]. Different methods are utilized to improve Wrec such as chemical doping, glass modification, multilayer structure design, and advanced sintering technology [14,15,16,17,18,19,20,21,22]. Based on our previous work, a binary solid solution of (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35TiO3 (BNT–BST) is considered as a good energy storage material due to “clamped” behavior in P–E loop and high dielectric constant r (~4000) at room temperature [25,26]. The phase structure, micrograph, dielectric temperature stability, and energy storage properties of Ba0.105Na0.325Sr0.245−1.5x 0.5xBi0.325+xTiO3 ceramics are investigated
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