High polarization stability of Sr modified Pb(Zr,Sn)NbO3 antiferroelectric ceramics

Bismuth ferrite-based lead-free multilayers with a high recoverable energy density of 6.74 J cm −3 and an efficiency of 77%, stable up to 125 °C. Lead-free ceramics with high recoverable energy density ( W rec ) and energy storage efficiency ( η ) are attractive for advanced pulsed power capacitors to enable greater miniaturization and integration. In this work, dense bismuth ferrite (BF)-based, lead-free 0.75(Bi 1−x Nd x )FeO 3 -0.25BaTiO 3 (BN x F-BT) ceramics and multilayers were fabricated. A transition from a mixed pseudocubic and R 3 c to a purely pseudocubic structure was observed as x increased with the optimum properties obtained for mixed compositions. The highest energy densities, W ∼ 4.1 J cm −3 and W rec ∼ 1.82 J cm −3 , were achieved for BN15F-BT, due to the enhanced breakdown field strength (BDS ∼ 180 kV cm −1 ) and large maximum polarization ( P max ∼ 40 μC cm −2 ). The multilayers of this composition possessed both a high W rec of 6.74 J cm −3 and η of 77% and were stable up to 125 °C. Nd doped BF-based ceramics with enhanced BDS and large W rec are therefore considered promising candidates for lead-free energy storage applications.

The 0.94(BNT–BST)–0.06KNN ceramic possesses an excellent stored energy storage density ( W s = ∼3.13 J cm −3 ), a recoverable energy storage density ( W r = ∼2.65 J cm −3 ), and maintains a relatively high efficiency ( η ∼ 84.6%). High-performance capacitors, which have high energy storage density as well as high discharge efficiency, are desired. In this study, we have designed and prepared novel and high quality (1 − x )(0.65Bi 0.5 Na 0.5 TiO 3 –0.35Bi 0.1 Sr 0.85 TiO 3 )– x (K 0.5 Na 0.5 NbO 3 ) [(1 − x )(BNT–BST)– x KNN, x = 0, 0.04, 0.06, 0.08, and 0.10] ceramics that demonstrated a remarkable energy storage capability, high efficiency, and ultrafast discharge speed. Particularly, the 0.94(BNT–BST)–0.06KNN ceramic possessed an excellent stored energy storage density ( W s = ∼3.13 J cm −3 ) and recoverable energy storage density ( W r = ∼2.65 J cm −3 ), and maintained a relatively high efficiency ( η = ∼84.6%) at a relatively low electric field of 180 MV m −1 , which is superior to those of the lead-free BNT-based energy-storage materials. Moreover, excellent temperature (20–120 °C) and frequency (1–100 Hz) stabilities of the 0.94(BNT–BST)–0.06KNN ceramic were also achieved. More importantly, the 0.94(BNT–BST)–0.06KNN ceramic exhibited an ultrafast discharge rate ( τ 0.9 = ∼1.01 μs), a high level of discharge energy density ( W d −1.21 J cm −3 ), and excellent reliability in energy storage performance by consecutive cycling. Moreover, this study also provides an effective approach to attain large energy-storage capability along with high efficiency in BNT-based ceramics for application in pulsed power capacitors.