Ceramic-based dielectric capacitors with a high power density are one of the most prospective energy-storage components, compared with Li-ion batteries and super-capacitors. Unfortunately, the energy-storage density of ceramic-based dielectric capacitors is one or two orders of magnitude lower than that of the batteries, which is restricted by the property of dielectric materials. Therefore, developing reliable and high-performance dielectric ceramic is a challenge in the field of dielectric capacitors. Among dielectric ceramics, antiferroelectic (AFE) material is one of the most promising candidates for energy-storage devices since they show a high maximum polarization (P_max), low remnant polarization (P_r), and a regulated AFE-ferroelectric (FE) phase transition electric field. Recent efforts are made to enhance energy-storage properties of ceramic by component design, ion-doping and material form construct. However, a superior η is always gained at the cost of a high W_rec, becoming a challenge for synergistically achieving a ultrahigh W_rec and a superior η.

High-purity Pb₃O₄ (≥95.0%, Sinopharm Chemical Reagent Co., Ltd., China), La₂O₃ (≥99.9%, Sinopharm Chemical Reagent Co., Ltd., China), Nd₂O₃ (>99.99%, Aladdin Biochemical Technology Co., Ltd., China), ZrO₂ (≥99.0%, Sinopharm Chemical Reagent Co., Ltd., China), and SnO₂ (≥99.5%, Sinopharm Chemical Reagent Co., Ltd.) were used as raw materials. Pb_0.98-1.5xLa_0.02Nd_x(Zr_0.60Sn_0.40)_0.995O₃ (PL100xNZS) was selected as a basic system. Nd³⁺ with a small ionic radius (i.e., 1.29 Å) was introduced in PLZS to replace Pb²⁺ (i.e., 1.49 Å) for enhancing electric filed-induced E_FE-AFE. A Pb_0.98-1.5xLa_0.02Nd_x(Zr_0.60Sn_0.40)_0.995O₃ component was designed and the ceramics were fabricated by a tape-casting method.

The crystallinity, phase structure and microstructure of PL100xNZS ceramics were analyzed by an X-ray diffractometer (Rigaku Co., Ltd., Japan) and a model TESCAN-MIRA3 field-emission scanning electron microscope (TESCAN Co., Czech). The dielectric properties of the PL100xNZS ceramics were measured by a computer-controlled Agilent E4980A LCR analyzer. The displace-electric field (D-E) hysteresis loops and current density-electric field curve were determined by a ferroelectric measurement system (Radiant Technologies Co., USA). The pulsed charge-discharge behaviors were determined by a model CFD-001 resistance-inductance-capacitance (R-L-C) electric circuit (Guoguo Technology Co., China).

The XRD patterns show that all the samples exhibit a perovskite structure with an orthorhombic phase. The SEM images show that a dense and compact microstructure appears in PL100xNZS ceramics. The average grain size is decreased by doping of Nd³⁺. The dielectric behavior of PL100xNZS ceramics as a function of temperature measured at 10 kHz and 25-400 ℃ indicates that there are three stages of dielectric constant with the increase of temperature, i.e., the rising, the plateau and the falling regions, which correspond to the AFE, multicell cubic (MCC) and single-cell cubic (PE_C) phases. The maximum polarization decreases at the same electric field, and the breakdown strength (BDS) increases with the increase of Nd³⁺ content due to the decreased grain size. The antiferroelectric-ferroelectric phase transition electric field (E_AFE-FE) increases as the Nd³⁺ content increases, because of a stable antiferroelectric phase. The enhanced BDS and increased E_AFE-FE imply a high energy-storage density. The recoverable energy-storage density and efficiency are critical parameters to characterize the material performance. Herein, the PL4NZS ceramic can be used as a promising energy-storage material because it exhibits a linear-like D-E loop with a large P_max (i.e., 60 μC/cm²) and a high BDS (i.e., 490 kV/cm). A large energy storage density of 14.8 J/cm³ is obtained in PL4NZS ceramic with a high efficiency of 85%. The calculated values of W_rec and η fluctuate slightly in the range of 6.18-4.88 J/cm³ with increasing the frequency. The discharge waveforms of PL4NZS ceramic at different electric fields are investigated at room temperature with an overdamped R-L-C electric circuit. The maximum value of W_dis is 4.4 J/cm³ at 300 kV/cm, and the t_0.9 is 28 ns. A large C_Dmax of 3 360 A/cm² and a high P_Dmax of 504 MW/cm³ are achieved at 300 kV/cm in PL4NZS ceramic, indicating that the PL4NZS ceramic has a great competitiveness in high power system applications.

The high energy-storage density and efficiency were realized in designed PL100xNZS ceramics fabricated by a tape-casting technique. The effects of Nd³⁺ doping on the microstructure, dielectric properties, ferroelectric properties and energy storage properties of the ceramics were investigated. The W_rec was 14.8 J/cm³ with a giant η of 85% at 490 kV/cm for PL4NZS ceramic. As the temperature increases, W_rec and η of PL4NZS ceramic increased slightly. Moreover, a high W_dis of 4.4 J/cm³, a large C_Dmax of 3 360 A/cm² and a high P_Dmax of 504 MW/cm³ were obtained in PL4NZS ceramic. It was indicated that PL4NZS ceramic could be used as a prospective dielectric material for energy-storage applications.