Diffuse Phase Transitions and Giant Electrostrictive Coefficients in Lead-Free Fe3+-Doped 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 Ferroelectric Ceramics

Superior Energy-Storage Performances under a Moderate Electric Field Achieved in Antiferroelectric-like Na0.5Bi0.5TiO3-Based Relaxor Ferroelectric Ceramics by a Synergistic Optimization Strategy

The progress of power systems and electronic devices promotes the development of lead-free dielectric energy-storage material. Particularly, Na0.5Bi0.5TiO3-based ferroelectric ceramics featuring large spontaneous polarization as well as wide dielectric adjustability and stability are highly recognized as promising candidates. However, their large remanent polarization (Pr) and low electric breakdown strength (Eb) result in unsatisfactory recoverable energy density (Wrec) and/or energy conversion efficiency (η), severely restricting their energy-storage applications. Herein, an effective synergistic optimization strategy has been proposed to gain superior energy-storage performances. Interestingly, the antiferroelectric-like (AFE-like) (1 - x)(Na0.3Bi0.38Sr0.28TiO3)-xBi(Mg0.5Zr0.5)O3 (x = 0.00, 0.05, 0.10, 0.15, and 0.20) relaxor ferroelectric (RFE) ceramics were constructed via the phase structure, the polar structure, and the defect dipole modulations. With Bi(Mg0.5Zr0.5)O3 increasing, the slim and pinched polarization-electric field hysteresis (P-E) loops become remarkably similar to the double-like P-E loops characterized by AFEs. Meanwhile, the strengthened Eb and delayed polarization saturation were also realized due to the enlarged band gap, refined grain size, and reduced free energy barrier. Consequently, superior energy-storage performances were achieved in this work. Noticeably, a large Wrec of 5.00 J/cm3 and a high η of 90.09% were realized in 0.85(Na0.3Bi0.38Sr0.28TiO3)-0.15Bi(Mg0.5Zr0.5)O3 RFE ceramics at a moderate electric field of 340 kV/cm. Additionally, excellent energy-storage and/or charge-discharge reliabilities in frequency (1-500 Hz), temperature (20-140 °C), and fatigue cycle (1-50,000) were confirmed. These satisfactory results not only indicate the promising prospects of 0.85(Na0.3Bi0.38Sr0.28TiO3)-0.15Bi(Mg0.5Zr0.5)O3 RFE ceramics in the dielectric energy-storage field but also verify the effectiveness of the synergistic optimization strategy proposed in this work.

Ultra-Weak Polarization-Strain Coupling Effect Boosts Capacitive Energy Storage

In pulse power systems, multilayer ceramic capacitors (MLCCs) encounter significant challenges due to the heightened loading electric field (E), which can lead to fatigue damage and ultrasonic concussion caused by electrostrictive strain. To address these issues, an innovative strategy focused on achieving an ultra-weak polarization-strain coupling effect is proposed, which effectively reduces strain in MLCCs. Remarkably, an ultra-low electrostrictive coefficient (Q33) of 0.012 m4 C-2 is achieved in the composition 0.55(Bi0.5Na0.5)TiO3-0.45Pb(Mg1/3Nb2/3)O3, resulting in a significantly reduced strain of 0.118% at 330 kV cm-1. At the atomic scale, the local structural heterogeneity leads to an expanded and loose lattice structure, providing ample space for large ionic displacement polarization instead of lattice stretching when subjected to the applied E. This unique behavior not only promotes energy storage performance (ESP) but also accounts for the observed ultra-low Q33 and strain. Consequently, the MLCC device exhibits an impressive energy storage density of 14.6 J cm-3 and an ultrahigh efficiency of 93% at 720 kV cm-1. Furthermore, the superior ESP of the MLCC demonstrates excellent fatigue resistance and temperature stability, making it a promising solution for practical applications. Overall, this pivotal strategy offers a cost-effective solution for state-of-the-art MLCCs with ultra-low strain-vibration in pulse power systems.

Strain evolution from the ferroelectric to the relaxor state in (0.67 - x)BiFeO3-0.33BaTiO3-xBi(Mg0.5Zr0.5)O3 lead-free ceramics

The BiFeO3-BaTiO3 solid solution exhibits enhanced electric properties due to its modified phase structure with relaxor characteristics and reduced leakage current. Despite these advancements, the underlying mechanism behind the phase transition from a ferroelectric to a relaxor state in BF-BT ceramics remains largely unexplored. Here, the evolution of strain in (0.67 - x)BiFeO3-0.33BaTiO3-xBi(Mg0.5Zr0.5)O3 ceramics is investigated, with a focus on the strain transition from a ferroelectric to a relaxor phase. A strengthening of relaxor behavior is observed in the modified rhombohedral (R) and pseudocubic (PC) phase structure, resulting in optimal strain (Suni = 0.25%, Spos = 0.24%) at x = 0.04. The enhanced strain is attributed to the promotion of domain switching and the presence of strong random fields, with polar nanoregions integrating into a long-range ordered matrix. Furthermore, a gradual increase in strain with rising temperature is noted, driven by increased polarization and the expansion of ferroelectric domains. This study underscores the critical role of structural modifications in augmenting the electric response of BF-BT ceramics, thereby advancing the development of lead-free piezoelectric materials.

Engineering Multiphase Phase Transitions for Exceptional Electrocaloric Performance and Ultraweak Electrostrictive Response in Ferroelectrics

In the pursuit of eco-friendly alternatives for refrigeration technology, electrocaloric materials have emerged as promising candidates for efficient solid-state refrigeration due to their high efficiency and integrability. However, current advancements in electrocaloric effects (ECEs) are often constrained by high temperatures and elevated electric fields (E-field), limiting practical applicability. Informed by phase-field simulation, this study introduces a (1-x)Pb(Yb1/2Nb1/2)O3-xPb(Mg1/3Nb2/3)O3 system, strategically engineered to incorporate highly ordered YN and disordered MN mixtures. The synergistic interplay between E-field/temperature-induced polarization reorientation and cation shift initiates multiple ferroelectric-antiferroelectric-paraelectric phase transitions. Our results demonstrate that under a moderate E-field of 50 kV cm-1, the x = 0.22 composition achieves remarkable performance with a giant temperature change (ΔT) of 3.48 K, a robust ECE strength (ΔT/ΔE) of 0.095 K cm kV-1, and a wide temperature span (Tspan) of 38 °C. Notably, the disrupted lattice structure contributes to ultralow electrostrains below 0.008%, with an average electrostrictive coefficient Q33 of 0.007 m4 C-2. The significantly weakened electrostrictive activity favors enhancing the performance stability of subsequent devices. This work introduces an innovative strategy for developing robust electrocaloric materials, offering substantial ΔT and low electrostrains, presenting promising advancements in ECE applications with an extended lifetime.

Lead-free ferroelectrics with giant unipolar strain for high-precision actuators

The trade-off between electrostrain and strain hysteresis for piezo/ferroelectric materials largely restrains the development of high precision actuators and remains unresolved over the past few decades. Here, a simple composition of (Bi0.5Na0.5)1-x/100Srx/100TiO3 in the ergodic relaxor state is collaboratively designed through the segregated domain structure with the ferroelectric core, local polarization heterogeneity, and defect engineering. The ferroelectric core can act as a seed to facilitate the field-induced nonpolar-to-polar transition. Together with the internal bias field caused by defect dipoles and adjusted through electric field cycling and heat treatment technology, a giant unipolar strain of 1.03% is achieved in the x = 30 ceramic with a low hysteresis of 27%, while the electric-field-independent large-signal piezoelectric strain coefficient of ~1000 pm/V and ultralow hysteresis of <10% can be obtained in the x = 35 ceramic. Intriguingly, the low-hysteresis high strain also exhibits near-zero remnant strain, excellent temperature and cycling stability.

A Highly Electrostrictive Salt Cocrystal and the Piezoelectric Nanogenerator Application of Its 3D-Printed Polymer Composite

Ionic cocrystals with hydrogen bonding can form exciting materials with enhanced optical and electronic properties. We present a highly moisture-stable ammonium salt cocrystal [CH3C6H4CH(CH3)NH2][CH3C6H4CH(CH3)NH3][PF6] ((p-TEA)(p-TEAH)·PF6) crystallizing in the polar monoclinic C2 space group. The asymmetry in (p-TEA)(p-TEAH)·PF6 was induced by its chiral substituents, while the polar order and structural stability were achieved by using the octahedral PF6- anion and the consequent formation of salt cocrystal. The ferroelectric properties of (p-TEA)(p-TEAH)·PF6 were confirmed through P-E loop measurements. Piezoresponse force microscopy (PFM) enabled the visualization of its domain structure with characteristic "butterfly" and hysteresis loops associated with ferro- and piezoelectric properties. Notably, (p-TEA)(p-TEAH)·PF6 exhibits a large electrostrictive coefficient (Q33) value of 2.02 m4 C-2, higher than those found for ceramic-based materials and comparable to that of polyvinylidene difluoride. Furthermore, the composite films of (p-TEA)(p-TEAH)·PF6 with polycaprolactone (PCL) polymer and its gyroid-shaped 3D-printed composite scaled-up device, 3DP-Gy, were prepared and evaluated for piezoelectric energy-harvesting functionality. A high output voltage of 22.8 V and a power density of 118.5 μW cm-3 have been recorded for the 3DP-Gy device. Remarkably, no loss in voltage outputs was observed for the (p-TEA)(p-TEAH)·PF6 devices even after exposure to 99% relative humidity, showcasing their utility under extremely humid conditions.

Ultrahigh Electrostrictive Effect in Lead-Free Ferroelectric Ceramics Via Texture Engineering

The electrostrictive effect, which induces strain in ferroelectric ceramics, offers distinct advantages over its piezoelectric counterpart for high-precision actuator applications, including anhysteretic behavior even at high frequencies, rapid reaction times, and no requirement for poling. Historically, commercially available electrostrictive materials have been lead oxide-based. However, global restrictions on the use of lead in electronic components necessitate the exploration of lead-free electrostrictive ceramics with a high strain performance. Although various engineering strategies for producing materials with high strain have been proposed, they typically come at the expense of increased strain hysteresis. Here, we describe the extraordinary electrostrictive response of (Ba0.95Ca0.05)(Ti0.88Sn0.12)O3 (BCTS) ceramics with ultrahigh electrostrictive strain and negligible hysteresis achieved through texture engineering leveraging the anisotropic intrinsic lattice contribution. The BCTS ceramics exhibit a high unipolar strain of 0.175%, a substantial electrostrictive coefficient Q33 of 0.0715 m4 C-2, and an ultralow hysteresis of less than 0.8%. Notably, the Q33 value is three times greater than that of high-performance lead-based Pb(Mg1/3Nb2/3)O3 electrostrictive ceramics. Multiscale structural analyses demonstrate that the electrostrictive effect dominates the BCTS strain response. This research introduces a novel approach to texture engineering to enhance the electrostrictive effect, offering a promising paradigm for future advancements in this field.

Lead-Free Textured Ceramics with Ultrahigh Piezoelectric Properties by Synergistic Design

Lead-free ceramics with superior piezoelectric performance are highly desirable in various electromechanical applications. Unfortunately, it is still challenging to achieve significantly enhanced piezoelectricity without sacrificing the Curie temperature (Tc) in current BaTiO3-based ceramics. To address this issue, a synergistic design strategy of integrating crystallographic texture, multiphase coexistence, and doping engineering is proposed here. Highly [001]c-textured (Ba0.95Ca0.05)(Ti0.92Zr0.06Sn0.02)O3 ceramics are synthesized through Li-related liquid-phase-assisted templated grain growth, with improved grain orientation quality (f of ∼96% and r of ∼0.16) achieved at substantially reduced texture temperatures. Encouragingly, ultrahigh comprehensive piezoelectric properties, i.e., piezoelectric coefficient d33 of ∼820 pC N-1, electrostrain Smax/Emax of ∼2040 pm V-1, and figure of merit d33 × g33 of ∼23.5 × 10-12 m2 N-1, are simultaneously obtained without sacrificing Tc, which are also about 2.3, 2.4, and 4.3 times as high as those of non-textured counterpart, respectively. On the basis of the experiments and theoretical modeling, the outstanding piezoelectric performance is attributed to more effective exploration of property anisotropy and easier polarization rotation/extension, owing to improved grain orientation quality, dissolution of templates into oriented grains, coexisting R + O + T phases, and domain miniaturization. This work provides important guidelines for developing novel ceramics with outstanding piezoelectric properties and can largely expand application fields of textured BaTiO3-based ceramics into high-performance and multilayer electronic devices.

Polarity Modulation Induced High Electrostrain Performance with Near-Zero Hysteresis in a (Sr0.7Bi0.2□0.1)TiO3-Based System

High-precision piezo actuators necessitate dielectrics with high electrostrain performance with low hysteresis. Polarity-modulated (Sr_0.7Bi_0.2□0.1)TiO₃-based ceramics exhibit extraordinarily discrete multiphase coexistence regions: (i) the relaxor phase coexistence (RPC) region with local weakly polar tetragonal (T) and pseudocubic (Pc) short-range polar nanodomains and (ii) the ferroelectric phase coexistence (FPC) region with T long-range domains and Pc nanodomains. The RPC composition features a specially high and pure electrostrain performance with near-zero hysteresis (S ∼ 0.185%, Q₃₃ ∼ 0.038 m⁴·C^-2), which is double those of conventional Pb(Mg_1/3Nb_2/3)O₃-based ceramics. Particular interest is paid to the RPC and FPC with multiscale characterization to unravel local structure-performance relationships. Guided by piezoelectric force microscopy, scanning transmission electron microscopy, and phase-field simulations, the RPC composition with multiphase low-angle weakly polar nanodomains shows local structural heterogeneity and contributes to a flat local free energy profile and thus to nanodomain switching and superior electrostrain performance, in contrast to the FPC composition with a macroscopic domain that shows stark hysteresis. This work provides a paradigm to design high-precision actuator materials with large electrostrain and ultralow hysteresis, extending our knowledge of multiphase coexistence species in ferroelectrics.

Enhanced Piezoelectric Properties in a Single-Phase Region of Sm-Modified Lead-Free (Ba,Ca)(Zr,Ti)O3 Ceramics

In ferroelectric materials, phase boundaries such as the morphotropic phase boundary (MPB) and polymorphic phase boundary (PPB) have been widely utilized to enhance the piezoelectric properties. However, for a single-ferroelectric-phase system, there are few effective paradigms to achieve the enhancement of piezoelectric properties. Herein, we report an unexpected finding that largely enhanced piezoelectric properties occur in a single-tetragonal-ferroelectric-phase region in the Sm-modified (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT-xSm) system. An electrostrain maximum (0.13%) appears in the single-phase region of the BZCT-0.5Sm composition with the maximum polarization (P_m = 18.37 µC/cm²) and piezoelectric coefficient (d₃₃ = 396 pC/N) and the minimum coercive field (E_C = 3.30 kV/cm) at room temperature. Such an enhanced piezoelectric effect is due to the synergistic effect of large lattice distortion and domain miniaturization on the basis of the transmission electron microscope (TEM) observation and X-ray diffraction (XRD) Rietveld refinement. Our work may provide new insights into the design of high-performance ferroelectrics in the single-phase region.

Large Room-Temperature Electrocaloric Response Realized in Potassium-Sodium Niobate by a Relaxor Enhancement Effect and Multilayer Ceramic Construct

The development of high-performance electrocaloric (EC) materials is crucial for solid-state refrigeration applied in micro-electromechanical systems. Herein, a large room-temperature EC response is realized in (1 - x)(K_0.49Na_0.49Li_0.02)(Nb_0.8Ta_0.2)O₃-xCaZrO₃ (KNLNT-xCZ) benefiting from a relaxor enhancement effect and multilayer ceramic construct. The relaxor enhancement effect is because the long-range order is broken by adding CaZrO₃, which is in favor of enhancing the temperature change (ΔT) and broadening the temperature span (T_span) at room temperature. A ΔT of 0.48 K in the KNLNT-12CZ ceramic is ∼5 times higher than that in the KNLNT-8CZ ceramic at 30 °C. KNLNT-12CZ also exhibits good temperature stability, and the T_span is up to 65 K. In addition, the multilayer ceramic construct improves the breakdown electric field (E_b) through diminishing defects, leading to a booming ΔT of 3.2 K at 30 °C under 250 kV cm^-1 via a direct measurement. The work proposes an avenue for developing high-performance EC materials with a large EC response and broad T_span in solid-state refrigeration.

Structure and Electrical Properties of Microwave Sintered BTS-BCT-xBF Lead-Free Piezoelectric Ceramics

Barium titanate (BT)-based ceramics are one of the promising piezoelectric materials for environment-friendly electro-mechanical transformation. However, high performance materials are often sintered at high temperatures, resulting in volatile components and increased energy consumption. Here, 0.82Ba(Ti_0.89Sn_0.11)O₃-(0.18-x)(Ba_0.7Ca_0.3)TiO₃-xBiFeO₃ (BTS-BCT-xBF) piezoelectric ceramics were prepared by microwave sintering (MWS) method, and the structure and properties were emphatically studied, aiming to reveal the regulatory mechanism of MWS on the structure and properties. Compared with conventional solid sintering (CS), the phase structure presents a similar evolution in MWS ceramics as a function of BF, while the more refined grain size and the denser structure are observed in MWS ceramics. The electrical properties (e.g., d₃₃, ε_r, tan δ, etc.) of MWS ceramics are superior to the CS ceramics owing to the refined grain size and denser microstructure. It is worth noting that the energy storage performance (e.g., energy storage density, energy storage efficiency) significantly outperformed expectations due to the slender hysteresis loop resulting from the smaller grain and high cubic phase. Therefore, the MWS sintering mechanism can further drive practical application of BT-based ceramics.

Comparison of contribution to phase boundary from A-site aliovalent dopants in high-performance KNN-based ceramics

Different influence of A-site aliovalent dopants, Bi3+ and Ca2+, on phase boundary and electrical properties in KNN-based ceramics.

Symmetry of the Underlying Lattice in (K,Na)NbO3-Based Relaxor Ferroelectrics with Large Electromechanical Response

The piezoelectric constant (d₃₃) and converse piezoelectric coefficient (d₃₃*) of a piezoelectric material are critically important parameters for sensors and actuators. Here, we simultaneously achieve a high d₃₃ of 595 ± 10 pC/N and a large d₃₃* of ∼776 ± 20 pm/V in (K,Na)NbO₃ (KNN)-based ceramics, which exceed those of PZT5H and PZT4 ceramics, presenting good potential for practical piezoelectric applications. Moreover, the ceramic exhibits a relaxor-like and diffuse dielectric behavior due to the occurrence of local heterogeneity. According to the experiments and atomic resolution polarization mapping by Z-contrast imaging, hierarchical architecture of nanodomains and even smaller polar nanoregions with multiphase coexistence caused by compositional modification is the structural origin of the enhanced piezoelectric properties in this work. This work would pave a practical way to future applications of lead-free KNN-based ceramics.

New Role of Relaxor Multiphase Coexistence in Potassium Sodium Niobate Ceramics: Reduced Electric Field Dependence of Strain Temperature Stability

The influence of relaxor behavior on strain behavior is less investigated in potassium sodium niobate [(K, Na)NbO₃, KNN] ceramics. Here, we report novel phenomena in the temperature-dependent strain behavior with the electric field of KNN-based ceramics with relaxation characteristics. The strain temperature stability is electric field dependent below the threshold electric field: temperature-dependent strain can be effectively improved by increasing the applied electric fields, while it remains almost electric field independent above the threshold electric field. Such a macroscopic property change can be well consistent with the following microscopic domain structure evolution. Little voltage dependence is found above a certain voltage by employing voltage-dependent piezoresponse hysteresis loops and domain switching under different temperatures, implying the contribution of domain behavior to the change of strain. Ergodic polar nanoregions (PNRs) are induced by the high-density domain walls among nanodomains in the relaxor samples, as revealed by the atomic-resolution polarization mapping with Z-contrast. The facilitated domain switching due to the lowered energy barrier and nearly vanished polarization anisotropy based on the PNRs with nanoscale multiphase coexistence can promote the electric field compensation for temperature effect. This work demonstrates the contribution of relaxor behavior to the electric field dependence of strain temperature stability in KNN-based ceramics.

Multifunctional BaTiO3-Based Relaxor Ferroelectrics toward Excellent Energy Storage Performance and Electrostrictive Strain Benefiting from Crossover Region

Lead-free relaxor ferroelectrics (RFEs) exhibit a broader variety of phenomena in comparison with the "canonical" lead-containing compositions, rendering them attractive for newly multifunctional materials with low-cost and eco-friendly processing. Here, guided by the characteristics of relaxor ferroelectrics, lead-free (1 - x)BaTiO₃-xKNbO₃ systems are conceived and optimized to construct a special crossover region, which brings multiple benefits including tiny hysteresis loss while pursuing high maximum polarization, and large electrostrictive strain with low hysteresis, targeting multifunctional applications of energy storage capacitors, and electrostrictive actuators. We obtained fine-grained 0.96BaTiO₃-0.04KNbO₃ ceramic with a crossover region where nanodomains and nanosized polar regions with highly dynamic coexist, achieving a large recoverable energy density of 2.03 J/cm³ (300 kV/cm) simultaneously with sky-high charge-discharge efficiency of 94.5%, where low-cost production and environmental issues are warranted. By utilizing the crossover region, superior temperature-stable energy storage capacity (without a drop from 20 to 130 °C) guarantees the practical use. Meanwhile, this strategy favors large electrostrictive strain (0.146%) with ultralow hysteresis in 0.96BT-0.04KN at 80 kV/cm, which is suitable for electrostrictive actuators. It is expected that this strategy will stimulate future studies on lead-free multifunctional RFEs toward energy storage capacitors or electrostrictive actuators with low-cost and environmental compatibility.

Emerging new phase boundary in potassium sodium-niobate based ceramics

A review of the newly emerging “new phase boundary” in potassium sodium niobate-based ceramics with high performance.

Significantly Enhanced Energy-Harvesting Performance and Superior Fatigue-Resistant Behavior in [001]c-Textured BaTiO3-Based Lead-Free Piezoceramics

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_0.94Ca_0.06)(Ti_0.95Zr_0.05)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 output power density compared to the nontextured counterpart while maintaining stable output features up to 10⁶ vibration cycles. The power densities, which increased from 6.4 to 93.6 μW/mm³ with increasing acceleration excitation from 10 to 50 m/s², are much higher than those reported previously on lead-free energy harvesters. This work represents a significant advancement in piezoelectric energy-harvesting field and can provide guidelines for future efforts in this direction.

Exceptionally High Piezoelectric Coefficient and Low Strain Hysteresis in Grain-Oriented (Ba, Ca)(Ti, Zr)O3 through Integrating Crystallographic Texture and Domain Engineering

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 (Ba_0.94Ca_0.06)(Ti_0.95Zr_0.05)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 (H_s) 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 from the reversible contribution, and can be ascribed to the piezoelectric anisotropy, the favorable domain configuration, and the formation of smaller sized domains in the BCTZ textured ceramics. This study paves a new pathway to develop lead-free piezoelectrics with both low strain hysteresis and high piezoelectric coefficient. More importantly, it represents a very exciting discovery with potential application of BT-based ceramics in high-precision piezoelectric actuators.

Giant Electrostrictive Response and Piezoresistivity of Emulsion Templated Nanocomposites

Using an emulsion road and optimizing the dispersion process, we prepare polymer carbone nanotubes (CNT) and polymer reduced graphene oxide (rGO) composites. The introduction of conductive nanoparticles into polymer matrices modifies the electronic properties of the material. We show that these materials exhibit giant electrostriction coefficients in the intermediate filler concentration (below 1 wt %). This makes them very promising for applications such as capacitive sensors and actuators. In addition, the values of the piezoresistivity measured in the high filler concentration situation are at least an order of magnitude greater than the one reported in the literature. This opens the way to use these materials for stress or strain sensor applications considering their giant responses to mechanical deformations.

Microstructure and electric properties of BCZT thin films with seed layers

Lead free Ba_0.99Ca_0.01Ti_0.98Zr_0.02O₃ (BCZT) thin films with seed layers were prepared by using sol–gel processing technique.

Large activation energy in aged Mn-doped Sr0.4Ba0.6Nb2O6 ferroelectric ceramics

Large activation energy and a different migration path of oxygen vacancy diffusion in Mn-doped SBN ferroelectric ceramics are revealed.