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The Al 2 O 3 -modified Pb 0.99 (Zr 0.95 Ti 0.05 ) 0.98 Nb 0.02 O 3 (PZT 95/5) ferroelectric ceramics with enhanced breakdown strength were prepared from PZT 95/5 powders coated with a thin Al 2 O 3 shell layer, which were fabricated by a Citrate-Chelation method followed by a conventional sintering process. The microstructure and electrical properties of the as-prepared ceramics as a function of Al 2 O 3 content were systematically investigated. The results reveal that Al 2 O 3 nanoparticles are successfully coated on PZT 95/5 powders to form the core–shell structure and well dispersed at the grain boundaries of the PZT 95/5 ceramic matrix after sintering, which strengthened the grain boundaries. In particular, compared with pure PZT 95/5 ferroelectric ceramics, PZT 95/5 ceramics with less than 1.0 wt% Al 2 O 3 inclusion possess the enhanced breakdown strength and energy density, of which the largest increment being 25.9% and 13.5%, respectively. It is indicated that the as-prepared PZT 95/5 ferroelectric ceramics may be a promising candidate for explosively driven power supply. [ABSTRACT FROM AUTHOR]

Abstract: Sr x Ba1−x Nb2O6 (with x=0.50, 0.45, 0.40 and 0.30) ceramics were synthesized by conventional solid-state method and sintered at 1350°C for 3h. The phase structure, microstructure, dielectric, ferroelectric and pyroelectric properties of obtained ceramics were systematically investigated. Pure tungsten bronze phase could be obtained in all ceramics. The dielectric characteristics showed that SBN ceramic was a relaxor with strong diffuse phase transition and weak frequency dispersion. As Sr molar fraction x increases from 0.30 to 0.50, the transition temperature T C decreased linearly while the diffusivity parameter γ declined from 1.88 to 1.68. The saturated polarization, remnant polarization and pyroelectric coefficient were also found to be enhanced in SBN ceramics with increasing Sr content. The pyroelectric coefficient of about 2×10−8 C/cm2K can be obtained for polarized SBN50 ceramics at room temperature. [Copyright &y& Elsevier]

Due to the high demand for dielectric materials with high energy density, the energy storage performance of antiferroelectric ceramic capacitors has always gained much attention. Polarization intensity is a key factor that is closely related to the energy storage density. However, thus far, there has been a lack of research studies or successful methods to effectively modulate polarization intensity. The behavior of the polarization process is complex and contains domain nucleation, growth, and flip-flapping. Based on this finding, the introduction of Nb5+ at the B-site was designed to influence the three stages of antiferroelectric polarization by regulating the balance between the ferroelectric and antiferroelectric phases, and eventually realized regulation of the saturation polarization intensity in the (Pb 1-1.5x La x)(Zr 0.5 Sn 0.43 Ti 0.07)O 3 antiferroelectric ceramics. The saturation polarization intensity has increased from 25.56 to 42 μC/cm2 with Nb5+ content increases from 0 to 4 mol% and the hysteresis was kept low, Pb 0.94 La 0.04 (Zr 0.65 Sn 0.35) 0.975 Nb 0.02 O 3 is the optimal component with a high releasable energy density of 8.26 J/cm3 and an energy storage efficiency of 90.31%. This work provides an in-depth explanation of the microscopic mechanism of antiferroelectric ceramic polarization and presents a novel approach for the composition design of high-energy storage density antiferroelectric ceramics. [ABSTRACT FROM AUTHOR]

Barium Strontium Titanate (Ba 1-x Sr x TiO 3 , BST) possesses the advantages of high permittivity, low remnant polarization and dielectric loss, suggesting great potential in the application of power capacitors. However, the low maximum polarization severely restricts the achievement of outstanding energy storage properties (ESP). Herein, we design a lead-free bulk ceramic: (1-x)Ba 0. 55 Sr 0 · 45 TiO 3 -xBi 0.5 Na 0. 5 TiO 3 [(1-x)BST-xBNT] (x = 0.1–0.4), prepared by two-step solid-state reaction method. The introduction of BNT contributes to (1) the boost of maximum polarization (from 21 μC/cm2 up to 32.6 μC/cm2) due to Bi3+ lone pair covalent effect (2) strong relaxor behavior (1.71≪ γ 1.84) derived from weakly coupled nanopolar regions, which can be verified by high activation energy E a = 0.341 eV at x = 0.3, improves the ESP and thermal stability of the ceramics. According to the above strategies, high W rec = 1.73 J/cm3 and η = 84.4% are achieved in the 0.7BST-0.3BNT ceramics at 206 kV/cm, which is preferable to the previous results regarding BST-based bulk ceramics. The excellent thermal stability (20–120 °C), frequency stability (1–500 Hz), as well as anti-fatigue characteristic (cycling number: 105) were obtained in the 0.7BST-0.3BNT. Furthermore, 0.7BST-0.3BNT ceramics exhibit high-power density (P D = 44.9 MW/cm3) and rapid discharge rate (t 0.9 = 99.2 ns) from 20 °C to 120 °C. This work provides a feasible way to achieve good energy storage and charge-discharge properties for pulse power energy storage systems. [ABSTRACT FROM AUTHOR]

(Pb, La)(Zr, Sn, Ti)O 3 (PLZST) ceramic is one of the most prospective antiferroelectric (AFE) materials for variety of functional applications including energy storage and converter. Systematic structural investigation of domain structures should be of fundamental importance for understanding the structure-property relationship in AFE ceramics. In this study, the hierarchical domain structures and modulated structures correlated to the compositional variation in (Pb 0.97 La 0.02) (Zr 0.50 Sn x Ti 0.50-x)O 3 (x = 0.375, 0.45 and 0.50) were observed and investigated in details by transmission electron microscopy. The PLZST ceramics show exclusively incommensurate modulated structures (IMS) whose modulation period changed from 9.37 to 6.15 and to 4.04 with increasing of the x value. The hierarchical domain structures include, in decreasing scales, AFE domains, incommensurate domains and nanodomains. The elementary domains in PLZST ceramics are pinstriped nanodomains which were formed based on IMS configuration but by frequent modulation of IMS periodicity and formation of faults. Nanodomains accumulated and then dissociated into incommensurate domains and AFE domains successively. The presently revealed structural characteristics in antiferroelectric PLZST may stimulate future researches on the evolution of IMS-based hierarchical domains under external physical fields, e.g. thermal or electrical, and their correlation to the physical performance. [ABSTRACT FROM AUTHOR]

Reversible domain switching in aged acceptor-doped ferroelectric ceramics is a powerful method to achieve electrostrain due to the exchange of nonequal crystalline axes of domains. Nevertheless, previous work suggested that the strain obtained via reversible domain switching in unpoled ceramics was much lower than theoretical value. In this paper, we demonstrate that the strain in poled and aged acceptor-doped ferroelectric ceramics can be significantly enhanced when the driving electric field is perpendicular to the poling direction, originating from the exchange of nonequel crystalline axes of more domains. Consequently, the electrostrain of poled and aged 0.1 wt% MnO 2 -doped 0.05Pb(Mn 1/3 Sb 2/3 )O 3 −0.50PbZrO 3 −0.45PbTiO 3 could reach 0.225% which was 4.17 times larger than that of unpoled sample under a low electric field of 15 kV cm −1 . Moreover, the corresponding normalized strain d 33 * reached 1500 pm V −1 which significantly exceeded the values reported in ferroelectric ceramics. Our work provide a general effective method to enhance the electrostrain behavior via reversible domain switching in aged acceptor-doped ferroelectric ceramics. [ABSTRACT FROM AUTHOR]

Abstract: Porous Pb (Zr0.95Ti0.05) O3/xMgO (PZT/MgO, x=0, 0.1, 0.2, 0.5 and 1.0wt%) ferroelectric ceramics were prepared with MgO nanoparticles as reinforcing phase. The effects of MgO nanoparticles on the phase, microstructure, electrical and mechanical properties of as-prepared ceramics were investigated. The results show that the grain size is reduced obviously when increasing the amount of MgO. Compared with pure porous PZT, T C of MgO-added PZT ceramics shifts to higher temperature. Moreover, dielectric, ferroelectric and piezoelectric properties show no much degradation. Further, PZT/MgO ceramics possess enhanced mechanical properties compared to pure porous PZT ceramics, the largest increment of the fracture toughness and hardness being 31.3% and 19.8%, respectively. The optimal electrical and mechanical properties are obtained with the addition of less than 0.5wt% MgO nanoparticles. [Copyright &y& Elsevier]