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Transparent ferroelectric ceramics are popular due to their ability to couple optical and electrical properties. However, simultaneously achieving high electrical and optical performance in ceramics remains a formidable challenge. By using the two-step sintering process combined with a rare earth doping strategy, xLa-24PIN-42PMN-34PT transparent piezoelectric ceramics were prepared, achieving the coexistence of the highest known d33 (>1000 pC/N), excellent transmittance (T = 66.2% at 1600 nm), and the piezoelectric properties decrease by only 26.8% when approaching TC. PFM and in situ XRD results indicate that the parallel stripe-like and watermark-like coexisting ferroelectric domain structures, which are induced by La3+ doping, generate large piezoelectric responses. Light scattering loss is reduced by the small size of the ferroelectric domain structure. Excellent thermal stability is ensured by the tetragonal-dominated morphotropic phase structure. This work provides a valuable idea for the subsequent preparation of transparent ferroelectric ceramics with high performance. [ABSTRACT FROM AUTHOR]

Ferroelectric photo‐thermochromic (PTC) materials with both high coloration contrast and high transparency have attracted great attention for their applications in "smart window" for non‐contact optical information storage. Nevertheless, it has been challenging to develop a ferroelectric PTC material that simultaneously meets the distinct transparency and coloration contrast requirements. Herein, dual rare‐earth ions doping of 1%Er‐(K0.5Na0.5)0.985La0.015NbO6 (Er‐KNLN) ferroelectric ceramics is aimed at increasing the optical transmittance and obtaining an ideal coloration contrast. The traditional solid‐state reaction is exploited for ceramics fabrication, and the optimal optical transmittance (≈70% at 900 nm) can be obtained due to finer grains, more symmetrical structure, and compact structure in samples sintered at a suitable temperature (such as ≤1165 °C). Contributed from the trapping and de‐trapping of charge carriers in vacancy‐related defects, the Er‐KNLN ceramics exhibit obvious PTC behavior and the novel impedance modulation is developed. The coupling between PTC behavior and optical transparency, lanthanide up‐conversion emission, patterned display, and room temperature impedance enables nondestructive rewritable and readout characteristics of multi‐mode "0" and "1" states. This work solves the main problems hampering the promising applications of ferroelectric materials and paves a way for developing multifunctional optical memory smart windows. [ABSTRACT FROM AUTHOR]

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories, optical switches and bio-imaging. However, those materials are basically opaque. In this work, we prepared a PC luminescent K 0. 5 Na 0. 5 NbO3-based ferroelectric transparent ceramic by modifying with Eu 3 + , Ba 2 + , Ti 4 + and Sr 2 + , which not only have good optical transmittances (∼ 60% at 900 nm), moderate ferroelectric properties and down-conversion photoluminescence (PL) properties, but also exhibit reversible PC behavior. After the illumination by xenon lamp, the colors of the ceramics change from pale green to gray, and then reversibly recover to their initial state via thermal stimulus (200∘C for 10 min). Interestingly, both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process. The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Transparent Er3+/La3+ co-doped (K 0.5 Na 0.5)NbO 3 ceramic was prepared by pressureless sintering. The XRD result shows that it possesses high symmetrical pseudo-cubic perovskite structure without impurity phase. The ceramic owns fine grains with the average size of ∼350 nm, uniform grain distribution, low porosity and high density. The optical transmittance of 0.3-mm ceramic is up to ∼60% in the visible region. Additionally, the ceramic has good dielectric properties with the relaxor-like behavior. Under an excitation of 980-nm, the temperature-dependent up-conversion luminescent color of Er3+ is stable below 523 K and adjustable (changing from green to tangerine color as temperature increases) above 523 K. The ratio of red to green emission intensity with temperature can provide a non-contact luminescent route to roughly detect the phase transition of this ferroelectric ceramic. Furthermore, the fluorescence temperature sensing performance of the ceramic was investigated and the maximum sensitivity is 0.003/K at 380 K. Due to optical, PL and electrical properties, the transparent ceramic shows potential in the application of electro-optical coupling devices. [ABSTRACT FROM AUTHOR]

Eco-friendly NaNbO 3 (NN)-based relaxor ferroelectric ceramics with high dielectric constants cannot meet the high piezoelectric activity quality factors (FOMs: d 33 × g 33) requirements of electromechanically coupled devices. To solve this issue, we successfully improved the piezoelectricity of NN-based relaxor piezoceramics while reducing the dielectric constant based on microstructural tuning by virtue of the chemical design and texturing engineering. Mainly affected by the highly <001> c orientation and relaxor MPB, the obtained novel 88.5NaNbO 3 –10Ba(Ti 0.7 Sn 0.3)O 3 –1.5NaSbO 3 texture ceramics enjoys an ultrahigh piezoelectric coefficient (d 33 = 423 pC/N), reaching a record high in NaNbO 3 -based lead-free ceramics. Meanwhile, a large FOMs value (d 33 × g 33 = 13.3·10−12 m2/N) is successfully realized due to the suppression of the dielectric constant. More importantly, the stable phase/domain evolution also encourages excellent temperature stability for piezoelectricity and FOMs. Especially for the piezoelectricity, when the annealing temperature is < 140 °C, the d 33 of the 1.5T ceramics can be stabilized ∼ 400 pC/N. Such excellent electrical temperature stability shows more competition in the reported NN-based piezoceramics. This work not only provides a design paradigm for high-performance piezoelectric materials, but also facilitates their development in electromechanical coupling devices. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel defect engineering is proposed to significantly refine the grain size of energy storage ceramics. • Achieving simultaneously high energy storage density, a rapid discharge time and superior transparency. • In-depth explanations are supported by the DFT calculations and the finite element analysis. • Bright-field TEM revealed the presence of ultrafine grains, PNRs and highly symmetric phase. Ceramic-based transparent dielectric materials are regarded as the best candidates for advanced energy storage and conversion materials because of their outstanding optical and electric properties. Nevertheless, due to the presence of low density, low band gap energy and large grain size, it is difficult to simultaneously obtain high energy storage density and high optical transmittance in lead-free based ceramics, which limiting their further development of practical applications. In this work, the relaxor ferroelectric ceramics of x mol% Er3+-doped 0.91 K 0.5 Na 0.5 NbO 3 -0.09Ba m Sr n TiO 3 (xEr-Sr m Ba n) were constructed via A-site non-stoichiometric defect engineering. It is worth noting that excessive addition of Sr and Ba, especially Sr, can significantly refine the grain size and domain size on account of vacancy-related defect pinning. Finally, high energy storage density (W = 6.39 J/cm3, W rec = 3.42 J/cm3) together with high optical transmittance (∼72% at 900 nm) can be achieved simultaneously in 0.25Er-Sr 1 Ba 0.5 due to the exist of dense structure, ultrafine grain size (<100 nm), small-sized nano-microdomains (i.e., PNRs, < 50 nm) and large bandgap energy (∼3.10 eV). Furthermore, a fast discharge time of 42 ns can also be realized. The above results indicate that the present study helps to promote the development of advanced transparent energy storage and conversion materials. [ABSTRACT FROM AUTHOR]

The lead-free Er 3+ -doped (K 0.48 Na 0.48 Li 0.04 )(Nb 0.96 Bi 0.04 )O 3 (KNLNB-Er-x) ceramics were fabricated by conventional pressureless sintering. They possess a tetragonal perovskite phase with dense microstructure. High transmittances of the ceramics are obtained both in the visible and infrared regions. The optical band gap energies of them are 3.07–3.11 eV, close to other KNN-based materials. The relaxor-like characteristics, good dielectric, ferroelectric and piezoelectric properties of the ceramics have been obtained. The up-conversion photoluminescence spectra have been studied and obvious color-tunable emissions have been observed by modulating temperature. The fluorescence intensity ratio (FIR) value based on green emissions at 533 and 555 nm in the temperature ranging from 300 to 750 K have been investigated, giving the maximum sensitivity of ~ 0.0038 K −1 . Furthermore, the FIR technique opens up a method to detect the Curie temperature of the ceramics. Owing to both optical and electrical properties, the KNLNB-Er-x transparent ceramics could be a promising candidate in the application of color-tunable solid-state lightings, optical temperature sensors, and electrical-optical coupling devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Excellent breakdown electric field and ultrahigh power density can be obtained in this work via multi-scale domain and microstructure engineering. • Multi-scale domain and microstructure engineering of BCZT-based ceramics. • Ultra-fast t0.9 (55 ns) and giant PD (369.9 MW/cm3) were realized. • High Wrec (5.32 J/cm3) and η (∼90%) obtained at 620 kV/cm. • Energy storage properties of BCZT-NBN-HP ceramic exhibit superior stability. Fulfilling the stringent demand of the miniature and eco-friendly pulsed power devices, development of high-energy-storage lead-free dielectric energy storage is critical. To achieve this goal, the mature strategy is to induce the formation of relaxor polar nano regions (PNRs) by means of constructing multiple solid solutions and element doping, which will inevitably lead to a significantly weakened polarization. How to better achieve the domain regulation is a challenge. Here, we reconsidered binary composite-induced domain evolution and designed a novel BT-based binary system with Na 0.7 Bi 0.1 NbO 3 (NBN) modification. By adjusting the NBN content to retain the long-range ferroelectric domains and applying the hot-pressing (HP) method to modulate grain size, the coupling of multi-scale domain morphology and voltage allocation can be achieved, simultaneously contributing to the high polarization, the enhanced breakdown strength and the optimized polarization response. Accordingly, a 130% enhancement to 5.32 J/cm3 in energy storage density, a high energy storage efficiency of ∼ 90%, an ultrafast discharge period of ∼ 55 ns, and a giant power density of ∼ 369.9 MW/cm3 were realized in our HP ceramics, superior to the existing dielectric ceramics. Moreover, the energy storage properties also exhibited superior frequency and thermal stability. The proposed synergistic optimization strategy of the domain morphology regulation and the microstructure adjustment is valuable for further energy storage design, and the enhanced energy storage properties promote the applications for lead-free dielectrics in energy storage devices. [ABSTRACT FROM AUTHOR]