capacitors), dielectric capacitors are promising candidates for advanced pulsed power applications owing to their high power density and fast charge/discharge speed. [6][7][8] Ceramic dielectrics show excellent temperature stability and mechanical robustness, are promising materials for use in extreme conditions. [9] Anti-ferroelectric ceramics (such as PbTiO 3 -and Pb(Zr,Ti)O 3 -based dielectrics) display double polarization-electric field (P-E) loops, which have tremendous potential for realizing high energy density. [10][11][12] However, most of these materials are Pbbased, whose toxic nature causes a series of environmental problems. Thus, leadfree ceramics have attracted considerable attention as a replacement to Pb-based materials. [7,[13][14][15][16][17][18] Until now, the low energy storage performance (low energy storage density of <4 J cm −3 and/or inferior efficiency of <80%) of lead-free ceramic capacitors hardly meet the increasing integration and miniaturization requirements. [19][20][21][22] Thus, it is imperative to improve the energy storage performance of lead-free ceramic capacitors.As shown in the schematic of Figure 1a, the energy storage density and efficiency of the dielectric capacitors are governed by the maximum polarization (P max ), remanent polarization (P r ), and dielectric breakdown strength (E BDS ). The combination of a large P max , small P r , and high E BDS is essential for realizing ultrahigh energy storage density and efficiency. Considering that the energy loss density (W loss ) is an inevitable part of ferroelectric ceramics, the recoverable energy storage density (W rec ) and energy efficiency (η) are key parameters for evaluating the energy storage performance of nonlinear dielectric ceramic capacitors. [9,17,23] It has been reported that BiFeO 3 (BF) possesses very high spontaneous polarization (≈100 µC cm −2 ), which is superior to most perovskite ferroelectrics, including BaTiO 3 , Bi 0.
An incommensurate modulated antiferroelectric phase is a key part of ideal candidate materials for the next generation of dielectric ceramics with excellent energy storage properties. However, there is less research carried out when considering its relatively low polarization response. Here, the incommensurate phase is modulated by stabilizing the antiferroelectric phase and the energy storage performance of the incommensurate phase under ultrahigh electric field is studied. The tape‐casting method is applied to construct dense and thin ceramics. La3+ doping induces a room‐temperature incommensurate antiferroelectric orthorhombic matrix. With little Cd2+, the extremely superior energy storage performances arose as follows: when 0.03, the recoverable energy storage density reaches ≈19.3 J cm‐3, accompanying an ultrahigh energy storage efficiency of ≈91% (870 kV cm‐1); also, a giant discharge energy density of ≈15.4 J cm‐3 emerges during actual operation. In situ observations demonstrate that these superior energy storage properties originate from the phase transition from the incommensurate antiferroelectric orthorhombic phase to the induced rhombohedral relaxor ferroelectric one. The adjustable incommensurate period affects the depolarization response. The revealed phase‐transition mechanism enriches the existing antiferroelectric–ferroelectric transition. Attention to the incommensurate phase can provide a reference for the selection of the next generation of high‐performance antiferroelectric materials.
Mechanical energy driven wireless charging technology has recently gained increasing attention. High-performance potassium sodium niobate (KNN) based texture ceramics and its potential application on energy harvesting device are the first...
A high-nuclearity nanoscale Cd24 cluster has been hydrothermally synthesized by assembly of Cd4-TC4A (H4TC4A = p-tert-butylthiacalix[4]arene) second building units (SBUs) and in situ generated peroxy(mono)phosphate PO53- groups and peroxyphenoxide groups of TC4A. The cluster was structurally characterized by single crystal X-ray diffractions. Photocatalytic studies revealed that the highest nuclearity Cd,S-co-rich Cd24 cluster exhibits enhanced photocatalytic water splitting activities compared to the sandwich Cd4(TC4A)2 (Cd4) cluster under the same conditions in the absence of a co-catalyst. The nanostructure of Cd24 incorporated both peroxyphosphate and peroxyphenoxide groups, which increased the metal coordination numbers to give more labile Cd-O/S bonds and is believed to be the key feature that enables the significant photocatalytic water splitting activities.
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