Effect of La substitution on energy storage properties of (Bi_0.2Na_0.2Ca_0.2Ba_0.2Sr_0.2)TiO₃ lead‐free high‐entropy ceramics

Abstract

In this study, a novel lead‐free high‐entropy ceramic (HEC) system, (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)(1–3x/2)LaxTiO3 (0 ≤ x ≤ 0.15) (abbreviated as BNCBST‐xLa), was designed to enhance energy storage performance through La substitution and prepared via a hydrothermal method. Results indicate that La doping at A site in BNCBST induces lattice distortion and further improves dielectric relaxation. Moreover, grain growth is inhibited by the La content, which results in an increase in the insulation resistance and thus significant enhancement in the electric breakdown strength (Eb). Accordingly, the system with x = 0.03 exhibits an excellent recoverable energy density (Wrec) of 2.43 J/cm3 and a high energy storage efficiency (η) of 85.5% under a great Eb of 245 kV/cm, together with wide temperature stability (Wrec and η vary within ± 8.3% and ± 1.1% at 30–150°C). The findings of this study suggest that the obtained La‐modified BNBCST HECs are promising for energy storage applications.

High energy storage performance of lead‐free Nb‐modified (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)TiO3 high‐entropy ceramics

“…Figure 8 shows the E b and energy storage performance of this study and those of other recently reported lead-free HECs. [10][11][12][13][14][52][53][54][55] It is obvious that the BNCBST-0.15Nb HEC synthesized in present work exhibits significant E b and W rec compared to the other HECs, verifying that Nb doping is an effective strategy to optimize energy storage performance for perovskite HECs.…”

“…12 In our previous studies, A-site disorder perovskite (Bi 0.2 Na 0.2 Ca 0.2 Ba 0.2 Sr 0.2 )TiO 3 and [(Bi 0.2 Na 0.2 Ca 0.2 Ba 0.2 Sr 0.2 ) 0.955 La 0.03 ]TiO 3 HECs were synthesized through hydrothermal method and exhibited strong dielectric relaxation behavior and good energy storage properties (W rec ∼ 2.43 J/cm 3 , E b ∼ 245 kV/cm). 13,14 These studies successfully took advantages of high entropy effect to obtain relaxor ferroelectrics and enhanced energy storage properties. However, the relatively low E b in these HECs is not ideal and inhibited the improvement of the energy storage properties, so further enhancement is required.…”

“…prepared (1− x )(Bi 0.5 Na 0.5 K 0.5 Ba 0.5 Ca 0.5 )TiO 3 ‐ x BaTiO 3 HECs through the solid‐state reaction and as‐prepared ceramics showed dielectric relaxation behavior, achieving a high W rec (2.24 J/cm 3 ) under 140 kV/cm at x = 0.20 12 . In our previous studies, A‐site disorder perovskite (Bi 0.2 Na 0.2 Ca 0.2 Ba 0.2 Sr 0.2 )TiO 3 and [(Bi 0.2 Na 0.2 Ca 0.2 Ba 0.2 Sr 0.2 ) 0.955 La 0.03 ]TiO 3 HECs were synthesized through hydrothermal method and exhibited strong dielectric relaxation behavior and good energy storage properties ( W rec ∼ 2.43 J/cm 3 , E b ∼ 245 kV/cm) 13,14 . These studies successfully took advantages of high entropy effect to obtain relaxor ferroelectrics and enhanced energy storage properties.…”

High-Entropy Lead-Free Perovskite Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties

“…The Raman modes within the range of 200-400 cm −1 are characteristic of Ti-O vibrations [65,66]. The modes between 400 and 700 cm −1 are representative of lattice distortion due to TiO 6 octahedral vibration and can be separated in two peaks in the (Bi 0.2 K 0.2 Ba 0.2 Sr 0.2 Ca 0.2 )TiO 3 powder [67]. For the range beyond 700 cm −1 , the modes can be assigned to the behavior of oxygen vibration/rotation [68].…”