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The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O 3 or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal grains along specific orientations. We present a seed-passivated texturing process to fabricate textured PZT ceramics by using newly developed Ba(Zr,Ti)O 3 microplatelet templates. This process not only ensures the template-induced grain growth in titanium-rich PZT layers but also facilitates desired composition through interlayer diffusion of zirconium and titanium. We successfully prepared textured PZT ceramics with outstanding properties, including Curie temperatures of 360°C, piezoelectric coefficients d 33 of 760 picocoulombs per newton and g 33 of 100 millivolt meters per newton, and electromechanical couplings k 33 of 0.85. This study addresses the challenge of fabricating textured rhombohedral PZT ceramics by suppressing the otherwise severe chemical reaction between PZT powder and titanate templates.

Polyetherimide nanocomposites with core–shell structured (Pb, La)(Zr, Sn, Ti)O3@Al2O3 antiferroelectric nanoparticle fillers deliver an ultra-high discharged energy density of 10.2 J cm−3 and a large efficiency of 83.5% at 150 °C.

Lead-free ceramics with both high piezoelectric response and good temperature stability are urgently demanded for electromechanical conversion devices. Unfortunately, owing to coexistence of polymorphic phases near room temperature (RT), enhanced piezoelectric properties were usually achieved with occurrence of strong temperature dependence in modified BaTiO3 (BT)-based ceramics. In this work, we demonstrate that tailoring grain orientations of tetragonal BT-based ceramics can effectively produce substantially enhanced and thermally stabilized piezoelectric response. Both c- and c-oriented tetragonal (Ba0.85Ca0.15) (Zr0.05Ti0.95)O3 (BCZT) ceramics with texture degrees F>90% were synthesized via templated grain growth. Interestingly, the ceramics textured along the c polar axis show much higher microscopic and macroscopic piezoelectric properties than those with nonpolar c texture, indicating an “extender” ferroelectricity nature. Compared with randomly oriented samples, the c-oriented ceramics exhibit simultaneously ∼1.6 times higher piezoelectric strain d33∗ (∼760 pm/V), 4.4 times higher piezoelectric figure of merit d33×g33 (8.8 × 10−12 m2/N), and better temperature stability (strain variation ≤5% between RT and 110 °C). Such thermally stabilized strain response can be mainly attributed to wide temperature range of tetragonal phase and stable domain structure. This work provides a promising route for further developing lead-free piezoceramics with high and temperature-insensitive performance, which can greatly broaden their application areas.

Substantial advancement has been made in recent years on lead-free piezoelectric materials, but up to date, it is still a challenge to make a true medical imaging ultrasonic array transducer with center frequency3 MHz. There are two major obstacles: the difficulty of fabricating large enough uniform lead-free piezoelectric materials with high piezoelectric coefficient, and the severe electrical impedance mismatch of an array element to the imaging system due to the relatively low dielectric constant of lead-free materials compared to lead-based piezoelectric materials. We resolved these two issues by employing texture engineering and stacking piezoelectric-layer design, which allowed us to fabricate an 80 element phased array transducer with the center frequency of 2.9 MHz and a bandwidth80% for human heart imaging. The high-quality lead-free (Ba

Inherent brittleness and low mechanical reliability usually inhibit the application of ceramic materials in many structural applications. In this work, we demonstrate that integrating crystallographic texture and second-phase toughening strategies can effectively improve fracture resistance and mechanical reliability in alumina multilayer composites. Composites consisted of equiaxed (1-x)Al2O3-xZrO2 and highly [0001]-textured Al2O3 layers were fabricated, and effects of ZrO2 amount on fracture behavior and mechanical properties of the composites were studied. Increasing ZrO2 amount x results in larger thermal expansion difference between equiaxed and textured layers. The composites with equiaxed layers containing 30 vol% ZrO2 exhibit high apparent fracture toughness Kapt, c ~11.7 MPa·m1/2 and work of fracture γWOF ~1540 J/m2, which correspond respectively to about 260% and 410% enhancements relative to those without ZrO2 addition. Moreover, adding ZrO2 remarkably reduces sensitivity of failure stress to flaw size in the multilayer composites, and the failure stress substantially increases with increasing ZrO2 content. The greatly enhanced mechanical performance achieved here can be mainly attributed to higher magnitude of compressive stresses, more crack bifurcations and longer crack deflection paths within the textured layers. This work can provide important guidelines for developing novel “bio-inspired” materials with improved fracture resistance and flaw tolerance behavior.

Owing to their importance in applications related to textured ceramics engineering, two-dimensional perovskite single-crystal microplates are highly desirable. In this work, (001)-oriented perovskite-structured BaTiO3 (BT) single-crystal microplatelets were fabricated from an Aurivillius-structured BaBi4Ti4O15 precursor via topochemical transformation. XRD, SEM, DTA, and TEM characterizations were performed to investigate the crystallization behavior and morphology evolution of the product at different reaction stages, with a focus on the formation mechanism of BT single crystalline microplatelets. Our results indicate that secondary recrystallization repaired the significant micro-structural/crystalline damage that was caused, thereby preserving the single-crystal structure during structural conversion. The subsequent epitaxial growth and replenishment through Ostwald ripening resulted in more regular shapes and narrower distributions of BT microplatelets. This study not only suggests suitable BT template candidates for the application of textured ceramics, but also provides new insights into a simple topochemical transformation strategy for manufacturing two-dimensional perovskite microcrystals.

Piezoceramics with both high strain response and excellent output stability are highly in demand for electronic actuator applications. Unfortunately, enhanced strains are generally accompanied by temperature and e-field instabilities for relaxor-PbTiO3 ferroelectrics near the curved morphotropic phase boundary (MPB). In this work, we report the simultaneous achievements of substantially enhanced piezoelectric strain (d33* ∼ 990 pm V−1), greatly improved temperature stability (strain variation below 10% over 25–150 °C) and excellent fatigue resistance (almost no strain variation at a bipolar e-field of 30 kV cm−1 up to 105 cycles) in a relaxor-PbTiO3 ferroelectric ceramic with controlled grain orientation along [001]c, based on integrating texture engineering and composite effect strategies. The temperature–insensitive strain response can be mainly attributed to the thermally stabilized er × P (dielectric permittivity × polarization) and stable domain response over a broad temperature range, which suppressed the adverse effect (strain variation ∼60% over 25–150 °C in the non-textured counterpart) caused by the intermediate ferroelectric phase transition. Besides, the inherent anisotropy properties and enhanced domain mobility in the textured ceramics further contribute to the substantially improved fatigue endurance. This work paves the way for exploring large and stable strain response in ferroelectrics with strongly curved MPB, and can also largely broaden application areas of relaxor-PbTiO3 ceramics to high-performance, stable and robust actuators.

High-performance piezoelectrics are pivotal to various electronic applications including multilayer actuators, sensors, and energy harvesters. Despite the presence of high Lotgering factor F001, tw...

Using a simple one-pot method, the reduction of liquid terminated-carboxyl fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.

The effects of CuO-doping on perovskite phase formation and reactive sintering of 28Pb(In1/2Nb1/2)O3-40Pb(Mg1/3Nb2/3)O3-32PbTiO3 ceramics were investigated, and the densification kinetics were compared with conventionally sintered ceramics. CuO-doping was observed by in situ x-ray diffraction to accelerate perovskite and suppress pyrochlore formation. 0.5 mol% CuO-doped PIN-PMN-PT ceramics sintered to ≥ 95% density as low as 790 °C. Comparable densification kinetics were observed with both conventional and reactive sintering. In the final stage of sintering, reactive sintering reduced the activation energy from 616 kJ/mol to 382 kJ/mol due to formation of a uniform 26–33 nm crystallite size microstructure that formed in situ at the onset of densification. Annealed reactively sintered ceramics also demonstrated equivalent ferroelectric behavior to conventionally sintered ceramics. We believe this work demonstrates a means to minimize material volatility during ceramic processing, an avenue for exploring co-firing with electrodes, as well as improved manufacturability through elimination of the perovskite powder synthesis step.

Electrocaloric refrigeration utilizing ferroelectrics has recently gained tremendous attention because of the urgent demand for solid-state cooling devices. However, the low room-temperature electrocaloric effect and narrow operation temperature window hinder the implementation of lead-free ferroelectrics in high-efficiency cooling applications. In this work, chemical engineering and thick-film architecture design strategies were integrated into a BaTiO

Piezoelectric energy harvesting has recently attracted substantial interest because of its ability to provide sustainable power for devices that consume very small amounts of energy. In this work, we propose a CuO-doping strategy to develop environmentally friendly (Ba, Ca)(Zr, Ti)O3 (BCZT) piezoelectric energy harvesters with both low sintering temperatures and excellent power generation performance. The CuO dopant greatly promoted the densification behavior of BCZT ceramics, yielding a densified and fine-grained microstructure at a sintering temperature reduced by 125 °C compared to that of undoped BCZT. Moreover, CuO addition substantially reduced the domain size compared to that of the undoped BCZT and thus facilitated domain switching in the ceramics. While maintaining the Curie temperature (Tc) at ∼120 °C, 0.50 mol% CuO-doped ceramics exhibited significantly enhanced electromechanical properties with a figure of merit d33×g33 of 6661 × 10−15 m2/N, high-field piezoelectric constant d33∗ of 873 pm/V, electromechanical coupling factor kp of 0.53 and energy conversion efficiency η of 97%. A high power density of 1.8 μW/mm3, which corresponds to a ∼360% improvement relative to that of the undoped BCZT, was achieved from 0.50 mol% CuO-doped BCZT energy harvesters at 10 m/s2 acceleration. These findings suggest the tremendous potential of CuO-doped (Ba, Ca)(Zr, Ti)O3 piezoceramics in high-power-density energy harvesting applications.

Solid-state cooling technology based on the electrocaloric effect is attracting increasing attention as an important alternative to traditional cooling systems in microelectronic and integrated electronics. Lead-free bulk ceramics are considered as one of the promising candidates for middle and large-scale electrocaloric cooling because of their environment-friendliness and large heat absorption capacity. However, the room temperature adiabatic temperature change (ΔT) in lead-free bulk ceramics has long been limited by their relatively low dielectric breakdown strength (Eb < 60 kV cm−1), hindering their practical applications. In this work, we propose to use the tape casting technique as a practicable strategy to enhance the densification and decrease the porosity of lead-free bulk ceramics for achieving a high Eb and a large room temperature ΔT. An ultrahigh room temperature ΔT (1.6 K) was realized in a (Ba0.95Ca0.05)(Ti0.94Sn0.06)O3 (BCTS) bulk ceramic prepared by the tape casting technique, which is 4 times larger than that of the lead-free bulk ceramics with a similar composition prepared by the conventional ceramic preparing approach. More significantly, unlike the other previously reported results, which only show high ΔT in an extremely narrow temperature range, ΔT of the BCTS bulk ceramic increases from 1.6 K to 2.0 K in the temperature range from 300 K to 345 K, which is comparable with that found in the lead-based bulk counterpart. Most importantly, this work opens up a new avenue to explore lead-free bulk ceramics with a large room temperature ΔT for solid-state refrigeration.

Piezoelectric energy harvesters have gained significant attention in recent years due to the strong demand of sustainable power sources for wireless sensor networks and portable/wearable electronics. However, the relatively low figure of merit (d × g) induced by thermodynamic constraints seriously hinders the enhancement of power generation capability in lead-free piezoelectrics. In this work, crystallographic texture and composite design strategies were integrated to develop novel 0–3 type (Ba, Ca)(Ti, Sn)O3/BaTiO3 (BCTS/BT) composites with highly [001]c-oriented and “core–shell” structured grains to resolve this challenge. Increasing texture degree F001 above 86% enabled rapid enhancements of piezoelectric charge/strain coefficients d33 and . Meanwhile, the inclusion of low-er BT microcrystals inside the oriented BCTS grains effectively suppressed the dielectric permittivity er of the composites, thus remarkably improving the piezoelectric voltage coefficient g33. Especially, the 98%-textured 0–3 composites demonstrated as high as ∼405% improvement in d33 × g33 value (17.0 × 10−12 m2 N−1), attributed to the strong piezoelectric anisotropy, the formation of much finer domains and the elastoelectric composite effect. The cantilever energy harvesters based on such composites possessed ∼560% enhancement in power density (4.5 μW mm−3) at 1 g acceleration relative to the non-textured counterpart, which significantly outperformed many previously reported lead-free piezoelectrics. This work provides a new important paradigm for developing high-performance viable green energy harvesters, which can largely expand the application fields of lead-free piezoelectrics.

To suppress the generation of oxygen vacancy during the PbZr0.53Ti0.47O3 (PZT) film synthesis process, herein, the 0–3 type Ag/PZT film is chosen as a prototype to systematically investigate the mechanisms of oxygen vacancy decrease and the relationship of ferroelectric properties. The uniform and dense films were successfully fabricated on fluorine tin oxide glasses (FTO) by facile sol–gel processes. It is confirmed the existence of silver nanoparticles in the film, indicating the composite ferroelectric films are of 0–3 type. When Ag doping mole concentration is 0.010 in the sol, a large remnant polarization (Pr) of ~ 50.7 µΧ/cm2 is got, which is 37.9 µΧ/cm2 for pure PZT. UV–vis spectrum confirms the generation of Ag2O in the process of mixing the sol. Furthermore, the oxygen vacancies caused by natural evaporation of lead specie are effectively reduced because of the decomposition of Ag2O, confirmed by X-ray photoelectron spectroscopy. This work points out the generated Ag2O as the intermediate product is the key to achieve high remnant polarization in Ag/PZT based film and make it as a promising candidate for memory applications.

The figure-of-merits of ferroelectrics for transducer applications are their electromechanical coupling factor and the operable temperature range. Relaxor-PbTiO3 ferroelectric crystals show a much improved electromechanical coupling factor k33 (88~93%) compared to their ceramic counterparts (65~78%) by taking advantage of the strong anisotropy of crystals. However, only a few relaxor-PbTiO3 systems, for example Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3, can be grown into single crystals, whose operable temperature range is limited by their rhombohedral-tetragonal phase transition temperatures (Trt: 60~120 °C). Here, we develop a templated grain-growth approach to fabricate -textured Pb(In1/2Nb1/2)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 (PIN-PSN-PT) ceramics that contain a large amount of the refractory component Sc2O3, which has the ability to increase the Trt of the system. The high k33 of 85~89% and the greatly increased Trt of 160~200 °C are simultaneously achieved in the textured PIN-PSN-PT ceramics. The above merits will make textured PIN-PSN-PT ceramics an alternative to single crystals, benefiting the development of numerous advanced piezoelectric devices., Only a few relaxors can be grown into crystals, which show high piezoelectricity, but their operable temperature range is limited by the low phase transition temperature. Here, the authors develop an approach to fabricate textured relaxor ceramics with elevated phase transition temperatures.

Dielectric ceramics are highly desired for electronic systems owing to their fast discharge speed and excellent fatigue resistance. However, the low energy density resulting from the low breakdown electric field leads to inferior volumetric efficiency, which is the main challenge for practical applications of dielectric ceramics. Here, we propose a strategy to increase the breakdown electric field and thus enhance the energy storage density of polycrystalline ceramics by controlling grain orientation. We fabricated high-quality -textured Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3 (NBT-SBT) ceramics, in which the strain induced by the electric field is substantially lowered, leading to a reduced failure probability and improved Weibull breakdown strength, on the order of 103 MV m−1, an ~65% enhancement compared to their randomly oriented counterparts. The recoverable energy density of -textured NBT-SBT multilayer ceramics is up to 21.5 J cm−3, outperforming state-of-the-art dielectric ceramics. The present research offers a route for designing dielectric ceramics with enhanced breakdown strength, which is expected to benefit a wide range of applications of dielectric ceramics for which high breakdown strength is required, such as high-voltage capacitors and electrocaloric solid-state cooling devices. The energy density of dielectric ceramic capacitors is limited by low breakdown fields. Here, by considering the anisotropy of electrostriction in perovskites, it is shown that -textured Na0.5Bi0.5TiO3–Sr0.7Bi0.2TiO3 ceramics can sustain higher electrical fields and achieve an energy density of 21.5 J cm−3.

Using a simple one-pot method, the reduction of liquid terminated-carboxyl fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH

Energy-harvesting utilizing piezoelectric materials has recently attracted extensive attention due to the strong demand of self-powered electronics. Unfortunately, low power density and poor long-term stability seriously hinder the implementation of lead-free piezoelectrics as high-efficiency energy harvesters. For the first time, we demonstrate that tailoring grain orientations of lead-free ceramics via templated grain growth can effectively produce ultrahigh power generation performance and excellent endurance against electrical/mechanical fatigues. Significantly improved fatigue resistance was observed in (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 grain-oriented piezoceramics (with ∼99% [001]c texture) up to 106 bipolar cycles, attributed to the enhanced domain mobility, less defect accumulation, and thus suppressed crack generation/propagation. Interestingly, the novel energy harvesters, which were developed based on the textured ceramics with high electromechanical properties, possessed ∼9.8 times enhancement in...

[0 0 0 1]-oriented alumina ceramics with texture fractions (F0001) ranging from ∼9.6% to 93.6% were prepared by templated grain growth (TGG) of nanoscale matrix. Ceramic density directly controls F0001. Impingement of textured grains can be observed at F0001 ≥ 58.4%. When fracturing samples along [0 0 0 1], the interfaces between basal surfaces of the impinged textured grains provide a favorable path for crack deflection, and the deflection distance becomes longer with increasing F0001. As a result of both crack defection and high density, optimum fracture toughness ∼4.6 MPa.m1/2 and flexural strength ∼589 MPa were achieved at F0001 = 93.6%, which are much higher than those obtained in the randomly oriented counterpart. This work can provide guidelines for the design and synthesis of novel structural ceramics with improved performance.

Further improving electromechanical properties and overcoming relatively low Curie temperature (Tc) of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-100xPT) are still two scientific issues. Here, we demonstrate a stable coexistence of monoclinic-tetragonal (MC-T) phases in ZnO-modified PMN-32PT (PMN-32PT:xZnO) due to the diffusion-induced substitution of Zn2+ for Mg2+. The Curie temperature, saturated polarization, remnant polarization, piezoelectric coefficient (Tc, Ps, Pr, d33) are increased from (160 °C, 22.0 μC/cm2, 13.3 μC/cm2, 350 pC/N) for x = 0 to (180 °C, 30.3 μC/cm2, 22.4 μC/cm2, 470 pC/N) for x = 0.06. Moreover, the thermal stability is improved. After annealing at 150 °C, the x = 0.06 sample shows retrained d33 value of 209 pC/N, about 4 times larger than that of x = 0 counterpart. The improved properties are attributed to the substituting increased polar nanoregions and easy domain switching in MC phase.

Highly dispersed α-Al2O3 microplatelets of various sizes and aspect ratios were prepared by additive-assisted molten salt synthesis. The effects of SiO2 and SiO2 + CaO additions on phase formation and morphology development of α-Al2O3 particles were investigated. Introducing additives are very effective in controlling α-Al2O3 morphology. SiO2 additive significantly enhances shape anisotropy of α-Al2O3 platelets, where a particle aspect ratio ∼23.8 was achieved, about 2.7–6.0 times higher than those of the platelets prepared without additives. When using SiO2 + CaO mixture, low concentration additive facilitates the growth of large platelets (∼9.8 µm), while increasing its content dramatically reduces the platelet size to ∼3.7 µm. These findings provide a new insight for the design and synthesis of novel advanced anisotropic microcrystals with improved quality.

Two-dimensional multifunctional perovskite microcrystals are very important for various applications due to their unique shape-dependent properties. In this work, we reported a facile topochemical approach to synthesize SrTiO3 perovskite microplatelets with remarkably improved characteristics from Aurivillius Bi4Ti3O12 precursors. A stable Bi-containing intermediate phase was not formed during the Aurivillius to perovskite structure transformation, which facilitates the achievement of high phase/composition purity in the product and is easier than many previously reported topochemical reactions for perovskites. Different from the polycrystalline nature of the converted perovskites as reported previously, secondary recrystallization healed the substantial microstructural/crystalline damage induced during structural conversion, retaining the single-crystal memory of Bi4Ti3O12 in the converted SrTiO3 particles. Benefiting from subsequent epitaxial growth and rearrangement via Ostwald ripening, the SrTiO3 microplatelets exhibited more regular shapes and narrower size distributions than the precursors, instead of only closely resembling the precursor morphologies as reported previously. For the first time, local piezoelectricity was detected from the individual SrTiO3 microplatelets using a piezoelectric force microscope. In particular, the piezoelectric response parallel to the [001] direction was much higher than that detected perpendicular to it, possibly being associated with the orientation-dependent surface flexoelectric effect. This work offers a facile in situ topochemical strategy for fabricating other two-dimensional perovskite microcrystals and opens the door to expanding the potential application fields of SrTiO3 microplatelets.

Controlling the morphology of plate-like α-Al 2 O 3 powders is essential since Al 2 O 3 platelets of different sizes and shapes are needed in numerous applications. In this work, non-aggregated α-Al 2 O 3 single-crystal platelets with diameters ranging from ~1 µm to more than 20 µm and thicknesses from ~0.1 µm to 1.3 µm were produced by molten salt synthesis. The effects of alumina precursor and molten salt compositions on phase formation and morphology development of Al 2 O 3 particles were investigated. Al 2 (SO 4 ) 3 precursor reacts with K 2 SO 4 salt to form K 3 Al(SO 4 ) 3 liquid phase at ~625 °C. The α-Al 2 O 3 seeds generated in-situ from the decomposition of K 3 Al(SO 4 ) 3 can serve as low energy nucleation sites, and thus accelerate complete transformation to α-Al 2 O 3 at much lower temperatures, yielding platelets of ≥20 µm diameter. Conversely, γ-Al 2 O 3 precursor is stable until higher temperatures, resulting in the formation of small hexagonal α-Al 2 O 3 platelets (1–2 µm in diameter) in the K 2 SO 4 molten salt. In addition to alumina precursors, the salt species also strongly affect the morphology of Al 2 O 3 particles. Compared with chloride salts (NaCl and KCl), sulfate salts (K 2 SO 4 and Na 2 SO 4 ) create favorable conditions for growth of higher- aspect-ratio α-Al 2 O 3 hexagonal platelets.

Both low strain hysteresis and high piezoelectric performance are required for practical applications in precisely controlled piezoelectric devices and systems. Unfortunately, enhanced piezoelectric properties were usually obtained with the presence of a large strain hysteresis in BaTiO3 (BT)-based piezoceramics. In this work, we propose to integrate crystallographic texturing and domain engineering strategies into BT-based ceramics to resolve this challenge. [001]c grain-oriented (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 (BCTZ) ceramics with a texture degree as high as 98.6% were synthesized by templated grain growth. A very high piezoelectric coefficient (d33) of 755 pC/N, and an extremely large piezoelectric strain coefficient (d33* = 2027 pm/V) along with an ultralow strain hysteresis (Hs) of 4.1% were simultaneously achieved in BT-based systems for the first time, which are among the best values ever reported on both lead-free and lead-based piezoceramics. The exceptionally high piezoelectric response is mainly...

Texture-engineered ceramics enable access to a vast array of novel texture-property relations leading to property values ranging between those of single crystals and isotropic bulk ceramics. Recently developed templated grain growth and magnetic alignment texturing methods yield high quality crystallographic texture, and thus significant advances in achievable texture-engineered properties in magnetic, piezoelectric, electronic, optical, thermoelectric, and structural ceramics. In this paper, we outline the fundamental basis for these texture-engineered properties and review recent contributions to the field of texture-engineered ceramics with an update on the properties of textured lead-free and lead-based piezoelectrics. We propose that further property improvements can be realized through development of processes that improve crystallographic alignment of the grain structure, create biaxial texture, and explore a wider array of crystallographic orientations. There is a critical need to model the physics of texture-engineered ceramics, and more comprehensively characterize texture, thus enabling testing of texture orientation-property relations and materials performance. We believe that in situ measurements of texture evolution can lead to a more fundamental and comprehensive understanding of the mechanisms of texture development.

We developed a facile one-pot method to synthesize multishelled hollow mesoporous SiO

(Ba 0.95 Ca 0.05 )(Ti 0.94 Sn 0.06 )O 3 - x mol% CuO ceramics were fabricated to investigate their domain structures and piezoelectric properties. The CuO additive significantly improved the densification behavior of the ceramics, resulting in a reduced sintering temperature by ~150 °C. Increasing x shifted the orthorhombic-tetragonal phase transition towards lower temperatures, and caused the specific ratio of tetragonal to orthorhombic phase to increase at room temperature. The herringbone domain patterns became much simpler and their number substantially decreased. The watermarks and parallel strips are the dominant domain configuration in ceramics with x =0.50 which show the optimum piezoelectric properties: d 33 ~516 pC/N, d 33 * ~996 pC/N, k p ~0.42, and Q m ~352. The underlying physical mechanisms for the enhanced piezoelectricity in the CuO-doped ceramics were discussed.

We investigated the synthesis mechanism and giant piezoelectricity of highly [0 0 1] c textured Pb(In 1/2 Nb 1/2 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PIN-PMN-PT) relaxor based ferroelectric ceramics (texture fraction ∼94%) with BaTiO 3 (BT) templates. The onset of texture occurred at ∼88% relative density (RD), and rapid increase in texture fraction happened with RD > 94%. A PbO-rich grain boundary liquid of ∼6–13 nm thickness, detected at oriented crystalline interfaces, facilitated epitaxial nucleation and subsequent [0 0 1] PIN-PMN-PT ||[0 0 1] BT growth of textured grains on BT templates. Interfaces between BT templates and PIN-PMN-PT textured grains were found to be coherent and defect-free at the atomic scale, and there was almost no barium diffusion across the interfaces during the texturing process. Nanodomains were clearly visible in the oriented grains. [0 0 1] c poling ordered the domain structures of textured ceramics and resulted in a more uniform domain size of several hundred nanometers. The textured ternary PIN-PMN-PT ceramics exhibited ∼200% improvement in piezoelectric response relative to their random counterparts, as a result of their piezoelectric anisotropy and engineered domain status along with higher mobility of domain walls.

Pure and 1.0 mol% La2O3, ZnO, and Cr2O3-modified 0.675BiFeO3–0.325BaTiO3 (BF–BT) multiferroic ceramics were prepared and comparatively investigated. For pure and La-, Zn-, and Cr-modified BF–BT, the average grain size is 415, 325, 580, and 395 nm, and the maximum dielectric constant temperature is 460°C, 430°C, 465°C, and 445°C, respectively. All additives weaken the ferroelectricity slightly. Zn- and Cr-modifications dramatically enhance the room-temperature magnetic properties, whereas La-modification has almost no effect on magnetic property. Especially, the Cr-modified BF–BT ceramics show switchable polarization and magnetization of 4.9 μC/cm2 and 0.27 emu/g at room temperature, the magnetoelectric coupling is confirmed by the magnetization-magnetic field curves measured on ceramics before and after electric poling. The mechanism responsible for the different effects of additive on microstructures and properties are discussed based on additive-induced point defect and second phase as well as diffusion-induced substitution. These results not only provide a promising room-temperature multiferroic material candidate, but also are helpful to design new multiferroic materials with enhanced properties.

Pb2+-doped (Sr1− xPbx)3Ti2O7 (SPT) ceramics were fabricated by a solid state reaction. The stability and lattice structure of Sr3Ti2O7 and Sr4Ti3O10 Ruddlesden–Popper (RP) phases were studied as a function of Pb2+ content and sintering atmosphere. X-ray diffraction indicates that SrO(SrTiO3)n RP phase formation is sensitive to the Sr:Ti ratio of the raw materials and is a complex circularly iterative process. When the PbO concentration is less than x = 0.03, pure Sr3Ti2O7 can be obtained. Sr4Ti3O10 was found to be the main phase in the SPT samples for x ≥ 0.075. Pb2+ stabilizes SrO(SrTiO3)n RP phases by substitution for Sr2+ which reduces the lattice stress of the RP phase. It was observed that SrO vaporization losses at high temperature can be compensated by the decomposition of the intermediate SrPbO3 phase at lower temperature.

CuO modified Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIN–PMN–PT) ternary relaxor based ferroelectrics with the composition near the morphotropic phase boundary were synthesized by two-step columbite precursor method. The introduction of CuO significantly improved the sinterability of PIN–PMN–PT ceramics, resulting in the full densification of samples at lower sintering temperatures. It also profoundly modified the crystal structure and fracture mode of the ceramics. Properly increasing CuO content led to the disappearance of rhombohedral-tetragonal phase transition, remarkably improved the Curie temperature (Tc), and made the ceramics more relaxorlike. The ternary ceramics doped with 0.25 wt% CuO possessed optimum piezoelectric properties (d33=584 pC/N, d33*=948 pC/N, and kp=0.68), high ferroelectric properties (Ec=9.9 kV/cm, and Pr=33.1 μC/cm2), low dielectric loss (tan δ=0.9%), and wider temperature usage range (Tc=225 °C). The obtained properties are much higher than those of previously reported PIN–PMN–PT based ceramics, indicating that CuO doped PIN–PMN–PT is a promising candidate for electromechanical applications with high performance and wide temperature/electric field usage ranges.

A phenomenological de-aging model with uniformly distributed defect dipoles for acceptor-doped ferroelectrics is proposed with the dynamic switching process of defect dipoles being simulated by the kinetic Monte Carlo method. The shifted P-E loops at different frequencies and temperatures were theoretically investigated. The results showed that the internal bias field increases with frequency and decreases with temperature. The scaling relation of the internal bias field with frequency was calculated at 298 K, 318 K and 338 K. The number of defect dipoles along different directions was calculated during the de-aging process, which is a key factor affecting the shape of P-E hysteresis loop. At 0.1 Hz, the defect dipoles can align with the polarization direction, but when the frequency is more than 10 Hz, they could not follow the field change and the internal bias field will saturate to a fixed value as the field frequency is beyond 100 Hz.

Energy-harvesting utilizing piezoelectric materials has recently attracted extensive attention due to the strong demand of self-powered electronics. Unfortunately, low power density and poor long-term stability seriously hinder the implementation of lead-free piezoelectrics as high-efficiency energy harvesters. For the first time, we demonstrate that tailoring grain orientations of lead-free ceramics via templated grain growth can effectively produce ultrahigh power generation performance and excellent endurance against electrical/mechanical fatigues. Significantly improved fatigue resistance was observed in (Ba

A concise and facile sol-gel method to prepare multiple magnetic SiO

Composites of Al 2 O 3 –5 vol.% t -ZrO 2 (ATZ) and Al 2 O 3 –30 vol.% m -ZrO 2 (AMZ) layers were designed with 3–1 connectivity to explore the effect of spatially-dependent residual stress and layer distribution on mechanical behavior. ATZ composites with ‘shallow’ and ‘deep’ regions of AMZ, defined relative to the distance from the surface, were fabricated. Four-point bending tests on indented 3–1 composites showed crack arrest in the first compressive AMZ layer and a fracture strength nearly independent of indent size (i.e. minimum strength); the failure occurring in the region with thicker outer ATZ layers (‘deep’ region). Region dependent crack growth resistance was measured on SEVNB specimens and compared to theoretical predictions using a fracture mechanics model. Spatially tailored constant strengths were obtained, ranging between 148 MPa and 470 MPa; the maximum value corresponding to a ‘shallow’ region with a relatively thicker AMZ compressive layer embedded close to the tensile ATZ surface. The 3–1 design concept allows the fabrication of ‘deep’ and ‘shallow’ embedded regions within a unique composite architecture, thus providing a preferential path for crack propagation, opening new possibilities for design of composite structures with spatially-tailored crack growth resistance.

In this work, a large size lead-free piezoelectric single crystal, (K,Na,Li)(Nb,Ta,Sb)O3 (KNLNTS) with the dimensions of 8.5 � 8.5 � 13.5 mm 3 was successfully grown by the top-seeded solution growth method. This KNLNTS single crystal with high compositional homogeneity is in the tetragonal phase at room temperature. The Curie temperature TC of the tetragonal-cubic phase transition temperature is 210 1C. The piezoelectric coefficients and electromechanical coupling factors of the [001]C oriented KNLNTS single crystal are d33¼172.55 pC/N, d31 ¼� 71.90 pC/N, k31 ¼0.327, k33¼0.523, and kt¼0.541. In addition, the crystal shows good thermal stability so that it can be used for making high temperature electromechanical devices.

Relaxor based ternary (0.60 − x)Pb(In1/2Nb1/2)O3–0.40Pb(Mg1/3Nb2/3)–xPbTiO3 ((0.60 − x)PIN–0.40PMN–xPT) polycrystalline ceramics were synthesized by two-step columbite precursor method. The effects of PIN/PT content on phase structure, microstructure, density, and dielectric, piezoelectric, ferroelectric and pyroelectric properties of the ternary ceramics were systematically investigated. A morphotropic phase boundary (MPB) near x = 0.34 was identified by X-ray diffraction and further confirmed by their respective electrical properties. Piezoelectric, ferroelectric and pyroelectric properties were enhanced for compositions near the MPB. The 0.26PIN–0.40PMN–0.34PT ceramics show optimum electrical properties: piezoelectric coefficient d 33 = 505 pC/N, planar electromechanical coupling factor k p = 62.5 %, remnant polarization P r = 32.1 μC/cm2, coercive field E c = 8.8 kV/cm, and room temperature pyroelectric coefficient p = 0.050 μC/cm2 °C. In addition, the rhombohedral–tetragonal phase transition temperature T rt and Curie temperature T c of the ternary ceramics were identified by the temperature dependence of dielectric and pyroelectric measurements, which are much higher than those of binary PMN–PT ceramics, indicating the expanded temperature usage range of the ternary ceramics. The results show that this ternary system is a promising candidate for electromechanical applications with high performance and wide temperature usage range.