Antiferroelectric materials that display double ferroelectric hysteresis loops are receiving increasing attention for their superior energy storage density compared to their ferroelectric counterparts. Despite the good properties obtained in antiferroelectric La-doped Pb(Zr,Ti)O -based ceramics, lead-free alternatives are highly desired due to the environmental concerns, and AgNbO has been highlighted as a ferrielectric/antiferroelectric perovskite for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm and high thermal stability of the energy storage density (with minimal variation of ≤±5%) over 20-120 °C, can be achieved in Ta-modified AgNbO ceramics. It is revealed that the incorporation of Ta to the Nb site can enhance the antiferroelectricity because of the reduced polarizability of B-site cations, which is confirmed by the polarization hysteresis, dielectric tunability, and selected-area electron diffraction measurements. Additionally, Ta addition in AgNbO leads to decreased grain size and increased bulk density, increasing the dielectric breakdown strength, up to 240 kV cm versus 175 kV cm for the pure counterpart, together with the enhanced antiferroelectricity, accounting for the high energy storage density.

The ultrahigh converse piezoelectric coefficient d*33 = 1444 pm V−1 and strain 0.070%, which are the highest values reported so far in lead-free ceramics, were achieved at the component of multiphase coexistence, suggesting that the BaTiO3–CaTiO3–BaSnO3 system is a promising lead-free alternative material for electromechanical actuator applications.

Lead-free dielectric ceramics with high recoverable energy density are highly desired to sustainably meet the future energy demand. AgNbO-based lead-free antiferroelectric ceramics with double ferroelectric hysteresis loops have been proved to be potential candidates for energy storage applications. Enhanced energy storage performance with recoverable energy density of 3.3 J/cm and high thermal stability with minimal energy density variation (<10%) over a temperature range of 20-120 °C have been achieved in W-modified AgNbO ceramics. It is revealed that the W cations substitute the B-site Nb and reduce the polarizability of B-site cations, leading to the enhanced antiferroelectricity, which is confirmed by the polarization hysteresis and dielectric tunability. It is believed that the polarizability of B-site cations plays a dominant role in stabilizing the antiferroelectricity in AgNbO system, in addition to the tolerance factor, which opens up a new design approach to achieve stable antiferroelectric materials.

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A series of Li 2 CO 3 -added (Ba 0.95 Ca 0.05 )(Ti 0.90 Sn 0.10 )O 3 (BCTS) ceramics were prepared by normal sintering at a low temperature of 1300°C; Their microstructure and electrical property evaluation were investigated with special emphases on the effect of Li 2 CO 3 addition. Adding Li 2 CO 3 significantly improves the sinterability of BCTS ceramics, resulting in a reduced sintering temperature by more than 150°C. The coexistence of R and T phases is confirmed by the Raman spectrum at room temperature for all samples and at a temperature range from -80°C to 40°C for sample with 3% mol Li 2 CO 3 addition. The specific ratio of R to T phase decreases with increasing temperature or Li 2 CO 3 addition. A higher e r is observed in T phase compared to R phase in the studied BCTS system. Better properties with d 33 = 485 pC/N, k p = 39%, and Q m = 191 were obtained for BCTS sample with 3% mol Li 2 CO 3 addition, which is attributed to the increased grain size and density along with the variation in the specific ratio of R to T phase. D. Damjanovic-contributing editor Manuscript No. 34011.