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Dy-doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ([(Ba0.85Ca0.15)0.99Dy0.01](Zr0.1Ti0.9)O3, 0.01Dy-BCZT) lead-free multifunctional ceramics were prepared by conventional solid-state sintering method, in which the effects of ceramic processing conditions were studied by structural analysis and performance characterization. The sintered 0.01Dy-BCZT ceramics have pure perovskite phase with composition near morphotropic phase boundary alongside apparent tetragonal distortion, high density and densified micro-morphology obtained via tailoring calcination and sintering temperatures. High resistivity, excellent dielectric performance and piezoelectricity were acquired, which were affected greatly by ceramic processing conditions. All samples exhibit excellent ferroelectric and strain properties, which approach intrinsic physical performance and have little dependency on ceramic processing conditions. Appearance of a strong broad emission peak, centred at ∼442 nm, is related to the 4F9/2 → 6H15/2 electron transition. Strong piezoelectric-fluorescent coupling effect was produced due to adding Dy and using BCZT piezoelectric matrix, which provides a promising choice in optoelectronic application field.

Two-dimensional (2D) transition-metal carbide Ti3C2TX (MXene) possesses good electrical conductivity, high specific surface areas and metal oxide-like surfaces, which make it ideal for application in supercapacitors with both high energy density and power density. However, similar to other 2D materials, the issue of self-stacking leads to narrower ion-transport channels, along with a drastic reduction in active sites, thus severely limiting the performance of MXene-based electrodes. To address this problem, this work proposes to introduce one-dimensional (1D) reduced graphene oxide (rGO) nanoribbons as spacers between MXene nanosheets to construct a composite structure for inhibiting self-stacking. As expected, owing to the steric effect and high aspect ratio of rGO nanoribbons, the fabricated MXene/rGO hybrid electrode, with the addition of 5 wt% graphene oxide (GO), exhibits a greatly improved specific capacitance (397.4 F g−1 at 5 mV s−1) and an unparalleled rate capability (with a capacitance retention of 52.9% at 2000 mV s−1). This work sheds significant light on the development of MXene-based materials for advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Perovskite (1-x)Ba0.9Sr0.1TiO3-xBi(Mg1/2Ti1/2)O3 (BST-BiMT-x) ceramics were prepared by sintering the corresponding powders synthesized by combining of solid state reaction method with citrate sol-gel and selfcombustion techniques. Submicron grains morphology, high density and large resistivity were obtained in the BST-BiMT-x ceramics. In addition, the BST-BiMT-0.1 and BST-BiMT-0.075 ceramics exhibit ferroelectric hysteresis loops with slim shape which lead to enhanced energy-storage properties. The energy-storage density of these two ceramics increases almost linearly with increasing the applied electric filed. The energy-storage density and efficiency at 25 kV/cm of the BST-BiMT-0.1 and BST-BiMT-0.075 ceramics sintered at 1200°C are 141.2mJ/cm3 and 79.3%, and 158.1mJ/cm3 and 76.7%, respectively, surpassing many recently reported values for ferroelectric/antiferroelectric ceramics. The enhanced energy-storage density and efficiency under low electric field can be attributed to the slim polarization-electric field hysteresis loops, high density accompanied by submicron grains morphology and pure perovskite structure.

A bottleneck characterized by high strain and low hysteresis has constantly existed in the design process of piezoelectric actuators. In order to solve the problem that actuator materials cannot simultaneously exhibit large strain and low hysteresis under relatively high electric fields, Nb5+-doped 0.975(Ba0.85Ca0.15)[(Zr0.1Ti0.9)0.999Nb0.001]O3-0.025(Bi0.5Na0.5)ZrO3 (BCZTNb0.001-0.025BiNZ) ceramic thick films were prepared by a film scraping process combined with a solid-state twin crystal method, and the influence of sintering temperature was studied systematically. All BCZTNb0.001-0.025BiNZ ceramic thick films sintered at different sintering temperatures have a pure perovskite structure with multiphase coexistence, dense microstructure and typical dielectric relaxation behavior. The conduction mechanism of all samples at high temperatures is dominated by oxygen vacancies confirmed by linear fitting using the Arrhenius law. As the sintering temperature elevates, the grain size increases, inducing the improvement of dielectric, ferroelectric and field-induced strain performance. The 1325 °C sintered BCZTNb0.001-0.025BiNZ ceramic thick film has the lowest hysteresis (1.34%) and relatively large unipolar strain (0.104%) at 60 kV/cm, showing relatively large strain and nearly zero strain hysteresis compared with most previously reported lead-free piezoelectric ceramics and presenting favorable application prospects in the actuator field. [ABSTRACT FROM AUTHOR]

A novel glass additive of 10Bi2O3‒5Li2O‒7.5Na2O‒7.5K2O‒21Nb2O5‒20.5SiO2‒10.5BaO‒11SrO‒4.5Al2O3‒0.5La2O3‒2TiO2 was melted to improve the energy‐storage properties of (Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3 (BLLMT) ceramics (BLLMT‒x wt% G), which overcomes the paradox between polarization and voltage endurance. The dielectric constant and resistance of BLLMT ceramics are improved by glass modification, while the grain size decreases. Consequently, excellent breakdown strength of 565.9 kV/cm is obtained, and the difference between maximum polarization and remnant polarization reaches up to 22.14 µC/cm2. Weibull distribution and finite element simulation prove that grain boundary density, grain size, resistance, and bandgap width have significant effects on the breakdown strength. Finally, outstanding energy‐storage density of 4.82 J/cm3 is obtained at x = 2, accompanied with an excellent pulse discharged energy density of 3.42 J/cm3, current density of 1226.12 A/cm2, and power density of 337.19 MW/cm3. Excellent temperature stability is gained with the variation of the pulse discharged energy density less than 10% at 20°C‒140°C. The outstanding pulse energy‐storage parameters are related to phase structure, small grain size, high grain boundary density, formation of liquid phase, increased ceramic resistance, and destroyed long‐range ordered ferroelectrics. This work provides a novel idea for fabricating glass to obtain excellent energy‐storage performance and promotes practical application of BaTiO3 ceramics. [ABSTRACT FROM AUTHOR]

To improve densification of the (Ba0.85Ca0.15)(Hf0.1Ti0.9)O3 (BCHT) ceramics prepared via powder injection moulding, MnO2 and Li2CO3 were used as sintering aids. The BCHT ceramics doped with different Mn- and Li-amount prepared by powder injection moulding in which paraffin was used as injection binder, have rather pure perovskite structure with complicated polymorphic ferroelectric phase coexistence. Polyhedral grains combined with nearly round shape grains with increased relative density and larger gains size were obtained at appropriate doping amount, related to the formation of liquid phase during sintering and increased mobility of ions due to the generation of point defects caused by heterovalent cations doping. TheMn- and Li-doped BCHT ceramics are displacement driven ferroelectrics with apparent diffused transition characteristic at different extent, relating to the morphotropic phase boundary composition and the variation of point defects induced by doping. Comparable or surpassing electrical performance was acquired, especially the dielectric breakdown strength was increased due to the improved sinterability. With appropriate doping amount, piezoelectricity larger than 300 pC/N can be obtained in the Mn- and Li-doped BCHT ceramics poled under low electric field.

Tin‐based perovskite is a competitive analog with lead halide perovskite, but there are significant gaps in power conversion efficiency (PCE) and stability between tin‐ and lead‐based perovskite solar cells. The characteristics of the easy oxidizability of Sn2+ and the rapid crystal growth for tin‐based perovskite are two major issues remained to be overcome. Herein, an additive (4‐pyridylamidoxime (4‐PyAO)) with multiple functional groups is introduced in the perovskite precursor solution. The oxidation of Sn2+ and the crystallization rate of perovskite are both retarded by 4‐PyAO addition. The prepared perovskite film is of high quality with fewer trap states and carrier recombination, and carrier extraction and transfer between the perovskite film and the adjacent carrier transport layer also become more efficient. As a result, the corresponding devices deliver the highest PCE of 9.02%, accompanied by short‐circuit current density, open‐circuit voltage, and fill factor of 19.90 mA cm−2, 0.63 V, and 72.48%, respectively. More importantly, the best device without encapsulation maintains 92% of its initial PCE after 2500 h aging test in nitrogen atmosphere, which may be attributed to a synergic effect among the different functional groups. [ABSTRACT FROM AUTHOR]

Via composition designing and sintering condition tailoring, high-density pure perovskite structure xBi(Ni0.50Ti0.50)O3–0.05BiFeO3–(0.95−x)Pb(Zr0.50Ti0.50)O3 [xBNT–0.05BF–(0.95−x)PZT, x = 0.19, 0.20, 0.21, 0.22, 0.23] ceramics were prepared by solid-state sintering method with adding additional 0.5 wt% LiBO2 sintering aid, whose sintering temperature was lower than that reported in literature. The xBNT–0.05BF–(0.95−x)PZT ceramics have mainly tetragonal structure confirmed by X-ray diffraction measurement and Raman spectroscopy, which is affected by composition and sintering condition. Broad dielectric peaks appear in all samples, and diffusive phase transition and dielectric frequency dispersion are obvious as well. The 0.20BNT–0.05BF–0.75PZT ceramics exhibit large piezoelectricity d33 = 386 pC/N combined with rather high dielectric constant maximum temperature Tm = 264°C, presenting enormous application potential in the high-temperature piezoelectric-related field. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF)/[(Ba0.85Ca0.15)0.995Sm0.005](Ti0.9Hf0.1)O3 (BCTH-0.005Sm3+) composite films with different BCTH-0.005Sm3+ filling amount were prepared via hydrothermal method and solution tape scraping process. The effects of BCTH:0.005Sm3+ filling amount were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrum (FTIR), ultraviolet-visible (UV-vis) transmission spectrum and photoluminescence spectrum. XRD confirms appropriate amount filling of BCTH:0.005Sm3+ promoting formation of β-phase, and FTIR reveals coupling between PVDF matrix and BCTH:0.005Sm3+ filler in the composite films. BCTH:0.005Sm3+ nanopowder filling increases optical transmittance, widens visible light region, and induces redshift of maximum absorption of pure PVDF. Emission intensity and fluorescence lifetime increase first and then decrease with increasing BCTH:0.005Sm3+ filling amount, and one-photon assisted down-conversion process dominates fluorescence emission in the PVDF/BCTH:0.005Sm3+ composite films. Overall, filling 2 wt% BCTH:0.005Sm3+ nanopowder is more helpful to improve comprehensive performance of the composite films, broadening prospect application in electrical and optical multifunctional fields. [ABSTRACT FROM AUTHOR]

(1-x)(Ba0.75Sr0.1Bi0.1)(Ti0.9Zr0.1)O3-x(Sb0.5Li0.5)TiO3 (abbreviated as BSBiTZ-xSLT, x = 0.025, 0.05, 0.075, 0.1) ceramics were prepared via a conventional solid-state sintering method under different sintering temperatures. All BSBiTZ-xSLT ceramics have predominantly perovskite phase structures with the coexistence of tetragonal, rhombohedral and orthogonal phases, and present mainly spherical-like shaped grains relating to a liquid-phase sintering mechanism due to adding SLT and Bi2O3. By adjusting the sintering temperature, all compositions obtain the highest relative density and present densified micro-morphology, and doping SLT tends to promote the growth of grain size and the grain size distribution becomes nonuniform gradually. Due to the addition of heterovalent ions and SLT, typical relaxor ferroelectric characteristic is realized, dielectric performance stability is broadened to ~120 °C with variation less than 10%, and very long and slim hysteresis loops are obtained, which is especially beneficial for energy storage application. All samples show extremely fast discharge performance where the discharge time t0.9 (time for 90% discharge energy density) is less than 160 ns and the largest discharge current occurs at around 30 ns. The 1155 °C sintered BSBiTZ-0.025SLT ceramics exhibit rather large energy storage density, very high energy storage efficiency and excellent pulse charge–discharge performance, providing the possibility to develop novel BT-based dielectric ceramics for pulse energy storage applications. [ABSTRACT FROM AUTHOR]