Relaxor State Research Articles

Structural insights into electric field induced polarization and strain responses inK0.5Na0.5NbO3modified morphotropic phase boundary compositions ofNa0.5Bi0.5TiO3-based lead-free piezoelectrics

${\mathrm{K}}_{0.5}{\mathrm{Na}}_{0.5}\mathrm{Nb}{\mathrm{O}}_{3}$ (KNN)-modified morphotropic phase boundary (MPB) compositions of the two ${\mathrm{Na}}_{0.5}{\mathrm{Bi}}_{0.5}\mathrm{Ti}{\mathrm{O}}_{3}$-based lead-free piezoelectrics, namely, $0.94{\mathrm{Na}}_{0.5}{\mathrm{Bi}}_{0.5}\mathrm{Ti}{\mathrm{O}}_{3}\text{\ensuremath{-}}0.06\mathrm{BaTi}{\mathrm{O}}_{3}$ (NBT-6BT) and $0.80{\mathrm{Na}}_{0.5}{\mathrm{Bi}}_{0.5}\mathrm{Ti}{\mathrm{O}}_{3}\text{\ensuremath{-}}0.20{\mathrm{K}}_{0.5}{\mathrm{Bi}}_{0.5}\mathrm{Ti}{\mathrm{O}}_{3}$ (NBT-20KBT) are model systems exhibiting large $(>0.4%)$ electric-field-driven strain. There is a general perception that (i) increasing KNN concentration monotonically weakens the direct piezoelectric response $({d}_{33})$, and (ii) maximum electrostrain occurs when KNN pushes the system in the fully ergodic relaxor state. We have examined these issues using various complementary techniques involving electrostrain, piezoelectric coefficient $({d}_{33})$, ferroelectric switching-current measurements, and field-driven structural studies on the global and local scales using laboratory and synchrotron x-ray diffraction, neutron powder diffraction, and ${\mathrm{Eu}}^{+3}$ photoluminescence techniques. Our investigations revealed the following important features: (i) In the low-concentration regime, KNN induces a tetragonal ferroelectric distortion, which improves the weak signal piezoresponse. (ii) Beyond a threshold concentration, in-phase octahedral tilt sets in and weakens the long-range ferroelectric order to partially stabilize an ergodic state. (iii) The maximum electrostrain (\ensuremath{\sim}0.6%) is achieved in the mixed (nonergodic + ergodic) state. (iv) The mixed state invariably exhibits a less-known phenomenon of field-driven ferroelectric-to-relaxor transformation during bipolar field cycling. (v) The enhanced electrostrain in the mixed state is associated with the electric field increasing the correlation lengths of the short-ranged tetragonal and rhombohedral ferroelectric regions without overall transformation of one phase to the other. We summarize the findings of this work in a comprehensive electric field composition (E-x) phase diagram. The findings reported here are likely to be true for other NBT-based MPB systems.

Tailoring high-energy storage NaNbO3-based materials from antiferroelectric to relaxor states

Reversible field-induced phase transitions define antiferroelectric perovskite oxides and lay the foundation for high-energy storage density materials, required for future green technologies. However, promising new antiferroelectrics are hampered by transition´s irreversibility and low electrical resistivity. Here, we demonstrate an approach to overcome these problems by adjusting the local structure and defect chemistry, delivering NaNbO3-based antiferroelectrics with well-defined double polarization loops. The attending reversible phase transition and structural changes at different length scales are probed by in situ high-energy X-ray diffraction, total scattering, transmission electron microcopy, and nuclear magnetic resonance spectroscopy. We show that the energy-storage density of the antiferroelectric compositions can be increased by an order of magnitude, while increasing the chemical disorder transforms the material to a relaxor state with a high energy efficiency of 90%. The results provide guidelines for efficient design of (anti-)ferroelectrics and open the way for the development of new material systems for a sustainable future.

Superior Capacitive Energy-Storage Performance in Pb-Free Relaxors with a Simple Chemical Composition

Chemical design of lead-free relaxors with simultaneously high energy density (Wrec) and high efficiency (η) for capacitive energy-storage has been a big challenge for advanced electronic systems. The current situation indicates that realizing such superior energy-storage properties requires highly complex chemical components. Herein, we demonstrate that, via local structure design, an ultrahigh Wrec of 10.1 J/cm3, concurrent with a high η of 90%, as well as excellent thermal and frequency stabilities can be achieved in a relaxor with a very simple chemical composition. By introducing 6s2 lone pair stereochemical active Bi into the classical BaTiO3 ferroelectric to generate a mismatch between A- and B-site polar displacements, a relaxor state with strong local polar fluctuations can be formed. Through advanced atomic-resolution displacement mapping and 3D reconstructing the nanoscale structure from neutron/X-ray total scattering, it is revealed that the localized Bi enhances the polar length largely at several perovskite unit cells and disrupts the long-range coherent Ti polar displacements, resulting in a slush-like structure with extremely small size polar clusters and strong local polar fluctuations. This favorable relaxor state exhibits substantially enhanced polarization, and minimized hysteresis at a high breakdown strength. This work offers a feasible avenue to chemically design new relaxors with a simple composition for high-performance capacitive energy-storage.

Distinct microstructure and property evolution of 0.76(Bi0.5Na0.5)TiO3-0.24SrTiO3 ferroelectric ceramics synthesized with different TiO2 reactants

Single phase 0.76(Bi0.5Na0.5)TiO3–0.24SrTiO3 ferroelectric ceramics have been synthesized with homogenous anatase and hierarchical rutile TiO2 raw reactants (BNST-A and BNST-R). Either calcined powder persists the microstructure characteristics of raw reactants. As the result, when the sintering temperature increases from 1000 to 1200 °C, the average grain size and density of BNST-A increase from 0.49 to 1.48 μm and 5.02 to 5.61 g/cm3, while those of BNST-R from 0.86 to 1.44 μm and 5.37 to 5.61 g/cm3. BNST-A illustrates a predominant ergodic relaxor state, and BNST-R prefers a non-ergodic relaxor state, as evidenced by the distinct polarization-electric field loops and current-electric field curves. Especially, such a distinct ferroelectric state is independent of sintering temperature. It is believed that the special hierarchical microstructure of rutile TiO2 reactant is beneficial to form denser ceramics with larger grains, and thus suppresses the contributions of polar nanoregions and defect-induced built-in field to ferroelectric property, leading to non-ergodic relaxor state. This work clearly demonstrates the nonnegligible effects of TiO2 reactants on the microstructure and properties of BNST ferroelectric ceramics.

Clarification on phase transition behaviors by local strain engineering in Bi1/2Na1/2TiO3–SrTiO3‐based ternary ceramics

AbstractThe stabilization of ergodicity plays an important role in realizing large strain in a Bi1/2Na1/2TiO3 (BNT)‐based relaxor, which is strongly related to the degree of random fields with respect to the randomly distributed different cations. To clarify the effects of different ionic radii, this study investigated and compared the microstructures, crystal structures, phase transition behaviors, and electrical properties of BNT–ST‐based ternary ceramics by modifying BiMeO3 (where Me = Al and Fe). It was observed that the stabilized relaxor states are different between BiFeO3‐/and BiAlO3‐modified BNT–ST ternary ceramics. As a result, it is suggested that phase transition (more precisely, the stabilization of ergodicity) can be influenced by the different internal strain in BNT–ST‐based ternary ceramics.

Electric field-induced two-step phase transformation and its contribution to the electromechanical strain in lead-free relaxor-based ceramics

Sodium bismuth titanate-based solid solutions are important lead-free piezoelectrics with potential applications. Large electromechanical strain is of particular interest, which can be realized via the structural change in the relaxor states under an electric field. In this work, a polycrystalline ceramic 0.85Na1/2Bi1/2TiO3–0.15BaZr0.2Ti0.8O3, in which a long-range ordered ferroelectric phase and a relaxor state coexist, has been investigated to unveil the origin of its electromechanical strain using various experimental techniques. An ergodic-relaxor to nonergodic-relaxor transition is first observed under a relatively weak electric field, and a more stable long-range ferroelectric phase is induced under a larger electric field. This two-step phase transformation is accompanied with the process of local polarization freezing as well as ferroelectric domain growth. The domain formation during the reversible phase transition is found to be the main contribution to the macroscopic strain. Our investigation provides an in-depth understanding of the origin of reversible electromechanical strain in the NBT-based relaxor-ferroelectric system.

Electrostatic energy storage performances of La(Ni2/3Ta1/3)O3‐modified Na0.5Bi0.5TiO3 lead‐free ceramics

AbstractCeramic capacitors with high electrostatic energy storage performances have captured much research interest in latest years. Sodium bismuth titanate (Na0.5Bi0.5TiO3)‐based ferroelectric ceramics show great potential due to their environment‐friendly composition, high polarization, and excellent relaxor properties. However, the nonergodic relaxor state of Na0.5Bi0.5TiO3‐based ceramics hampers the decrement of remanent polarization, leading to poor energy storage performance. Herein, the (1 − x)Na0.5Bi0.5TiO3–xLa(Ni2/3Ta1/3)O3 ceramics were designed to generate the transformation between nonergodic and ergodic relaxor state. As a result, the ceramics exhibit improved dielectric relaxation, slim polarization–electric field loops, and flattened current–electric field curves due to highly dynamic polar nanoregions. Particularly, the 0.85Na0.5Bi0.5TiO3–0.15La(Ni2/3Ta1/3)O3 ceramics show large breakdown electric field Eb (345 kV/cm), high recoverable energy density Wrec (3.6 J/cm3), and efficiency η (80.6%), revealing potential applications in electrostatic energy storage.

Electric-field-induced non-ergodic relaxor to ferroelectric transition in BiFeO3-xSrTiO3 ceramics.

While BiFeO3-based solid solutions show great promise for applications in energy conversion and storage, realizing this promise necessitates understanding the structure-property relationship in particular pertaining to the relaxor-like characteristics often exhibited by solid solutions with polar-to-non-polar morphotropic phase boundaries. To this end, we investigated the role of the compositionally-driven relaxor state in (100 - x)BiFeO3-xSrTiO3 [BFO-xSTO], via in situ synchrotron X-ray diffraction under bipolar electric-field cycling. The electric-field induced changes to the crystal structure, phase fraction and domain textures were monitored via the {111}pc, {200}pc, and 1/2{311}pc Bragg peaks. The dynamics of the intensities and positions of the (111) and (111̄) reflections reveal an initial non-ergodic regime followed by long-range ferroelectric ordering after extended poling cycles. The increased degree of random multi-site occupation in BFO-42STO compared to BFO-35STO is correlated with an increase of the critical electric field needed to induce the non-ergodic-to-ferroelectric transition, and a decrease in the degree of domain reorientation. Although both compositions show an irreversible transition to a long-range ferroelectric state, our results suggest that the weaker ferroelectric response in BFO-42STO is related to an increase in ergodicity. This, in turn, serves to guide the development of BFO-based systems into promising platform for further property engineering towards specific capacitor applications.

Probing the effect of Zn2+ on the local structure, dielectric and magnetic properties of La2CuMnO6 by solid state synthesis

The comparable ionic-radius cation substitution provides a route to investigate the origin of the physical properties of ceramics on the local structure and electronic charge state background. In analogy to our previous work [19] of La2CuMnO6 (LCM) prepared via solid-state route, here we are reporting the effect of Zn substitution at the Cu site of LCM. The detailed structural analysis confirmed the Jahn-Teller (JT) distortion in LCM and Zn2+ substituted LCM (i.e., LCZM) ceramics. Raman analysis further confirmed the JT distortion in these oxides. O K-edge and Mn K-edge XANES spectra confirmed the mixed hybridization states for Mn. A frequency-dependent relaxor state was observed in the dielectric study of LCM and LCZM. The dielectric responses of these systems are prominently driven by electron-phonon coupling. Their magnetic studies showed positive-Curie temperature (TC) and non-zero coercivity, indicating the ceramics' canted-antiferromagnetic nature.

Optimizing strain response in lead-free (Bi0.5Na0.5)TiO3-BaTiO3-NaNbO3 solid solutions via ferroelectric / (non-)ergodic relaxor phase boundary engineering

Lead-free bismuth sodium titanate (Bi0.5Na0.5)TiO3 (BNT) and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized. In this work, a large strain response of 0.61% is achieved in lead-free (0.94-x%)(Bi0.5Na0.5)TiO3-0.06BaTiO3-x%NaNbO3 (x = 0 –6, BNT-6BT-xNN) ceramics with the composition of x = 3.5 in a pseudo-cubic structure. Coexistence of ferroelectric (FE) and relaxor (RE) domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor (ER) and non-ergodic (NR) states thanks to the substitution of antiferroelectric NN. BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature (RT) and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state. This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.

Giant Negative Electrocaloric Effect over an Ultra-Wide Temperature Region in Relaxation Frozen State Ferroelectrics

A giant negative electrocaloric effect with the electrocaloric temperature change range from -27.3 to -9.8 K over an ultra-wide temperature region of 260 K (-180 to 80 °C) is obtained in a relaxation frozen state ferroelectric film of Bi5Ti3AlO15. A strategy is proposed to extend the temperature region of the electrocaloric effect by gradually slowing and locally freezing the relaxation dynamics. The slow and frozen nanodomains below freezing temperature Tf of ∼80 °C do not yield to the applied electric field but are noncolinear to the field, which results in an inverse configuration entropy change and negative electrocaloric effect over an ultra-wide temperature region in frozen relaxor state ferroelectric films. A semiphenomenological model based on modified Ginzburg-Landau-Devonshire theory is presented to reveal the evolution of the slowing and freezing of the nanodomains. The breakthroughs in the operating temperature region and cooling temperature change make relaxation frozen state ferroelectrics excellent electrocaloric refrigeration materials.

Regulating ferroelectric polarization and dielectric properties of BT-based lead-free ceramics

The ternary system of BaTiO3 (BT) -based lead-free ceramics ((1-x)BaTiO3-x(0.94 Sr0.7Bi0.2TiO3-0.06BiMg0.5Ti0.5O3) are investigated on their structural, dielectric and ferroelectric properties. The structural evolution is identified from the tetragonal phase (P4mm) to the pseudocubic phase with increasing the dopant concentration x. The gradually diffusive dielectric peak and highly dispersive relaxor behaviors are recognized, indicating the transformation from ferroelectric to relaxor state. Meanwhile, the ceramics are characterized by the slim polarization hysteresis loops associated with polar nano-sized cluster formation. Complex impedance spectroscopy reveals the electrical inhomogeneities with enhanced boundary effect caused by the excessive addition, leading to the abnormally degraded electric breakdown strength. Combined with the X-ray photoelectron spectroscopy, the oxygen vacancy hopping mechanism is proposed for the high dopant concentration, contributing to the diffuse dielectric response. As a result, optimized energy-storage density and efficiency are simultaneously obtained at a relatively low electric field. All these features demonstrate an effective route in the composition modulation of BT-based dielectric capacitor ceramics that not only the formation of polar nano regions but also the electrical homogeneities can greatly influence the comprehensive dielectric performance.

Ferroic glass behavior in (Bi,Na)TiO3-based lead-free electroceramics

Ferroic glass materials, that is, relaxors, spin glasses, and strain glasses attract special attention because of their intriguing physical properties and potential for novel technological applications. Here, several characterization techniques are used to demonstrate the occurrence of simultaneous relaxor and strain glass states in the ternary lead-free xBi0.5Na0.5TiO3-yBi0.5K0.5TiO3-zBaTiO3 (BNBK) system. Hysteresis and current density loops measurements at different temperatures for a BNBK ceramic showed typical characteristics observed in BNT based ceramics containing the tetragonal P4bm phase. Above 400 K, slim loops like those of ferroelectric relaxors are observed. A phase transition with simultaneous relaxor and strain glass character is revealed by the dielectric and anelastic characterizations, which opens up a wide spectrum of possible applications. The minimum of elastic modulus shifts to higher temperatures as the frequency increases, obeying the Vogel-Fulcher relation, which clearly shows the occurrence of a strain glass state in this material. Similar characteristics are observed in the imaginary part of the dielectric permittivity, which demonstrates the relaxor character of this phase transition. The origin of this phenomenon was elucidated with the help of structural characterizations, such as Raman spectroscopy and high-resolution synchrotron X-ray diffraction, at different temperatures. This work provides an in-depth understanding of the structural changes that determine the phenomenology behind the observed ferroic glass behavior and the ferroelectric, dielectric, and mechanical properties of this ternary ceramic composition.

Origin of the crossover from ferroelectric to relaxor in tetragonal tungsten bronzes

The polar behavior of tetragonal tungsten bronze (TTB) (SrxBa1−x)Nb2O6 (SBN) is known to vary from normal ferroelectric to relaxor when x > 0.5. However, the mechanism triggering this crossover is still unclear. We study the role of the relative occupancy of the available interstices (A1, A2) in the TTB structure and use the residual entropy calculation approach, and experimental x-ray diffraction and dielectric data obtained on SBN and Ca-doped SBN, to reveal the key parameters at play in the polar response. We show that once half of Sr occupies the A2 sites, the crossover takes place. Concomitantly, the residual entropy from the randomness of the cationic arrangement exhibits a high entropy with an energy higher than 12 J K−1 mole−1 when x > 0.5 corresponding to the relaxor behavior occurrence. These findings provide comprehensive and quantitative tools to understand and predict the emergence of the relaxor state in other TTBs and other crystalline structures.

Design of superior electrostriction in BaTiO3‐based lead‐free relaxors via the formation of polarization nanoclusters

AbstractElectrostrictive materials have wide applications in modern high‐precision electronic devices. Driven by growing environmental concerns, there is demand for lead‐free materials with superior electrostriction behaviors. In this study, we demonstrate a record‐high electrostrictive coefficient of ~0.0712 m4 C−2 in perovskite ferroelectric ceramics, along with hysteresis‐free strain as well as excellent frequency and thermal stabilities, in lead‐free BaTiO3‐based ceramics through a polarization nanocluster design. By appropriately introducing Li+ and Bi3+ into the BaTiO3 lattice matrix, the long‐range ferroelectric ordering can be broken, and polarization nanoclusters can be formed, resulting in a relaxor state with concurrently suppressed polarization and maintained electro‐strain. A three‐dimensional atomic model constructed using advanced neutron total‐scattering data combined with the reverse Monte Carlo method indicates the existence of Bi and Li segregations at the subnanometer scale, which confirms the prediction made by density functional theory calculations. Such a short‐range chemical order destroys the long‐range ferroelectric order of the off‐centered Ti polar displacements and leads to the embedding of Li+/Bi3+‐rich polar nanoregions in the Ba2+‐rich polarization disorder matrix. Further, a completely reversible electric‐field‐induced lattice strain is observed, giving rise to pure electrostriction without hysteresis behavior. This work provides a novel strategy for developing lead‐free relaxor ferroelectrics with high electrostriction performance.image

Optimized strain performance in -textured Bi0.5Na0.5TiO3-based ceramics with ergodic relaxor state and core—shell microstructure

Herein, a high strain of ∼0.3% with a small hysteresis of 43% is achieved at a low electric field of 4 kV/mm in the highly <001>-textured 0.97(0.76Bi0.5Na0.5TiO3−0.24SrTiO3)−0.03NaNbO3 (BNT−ST−0.03NN) ceramics with an ergodic relaxor (ER) state, leading to a large normalized strain (d33*) of 720 pm/V. The introduction of NN templates into BNT−ST induces the grain orientation growth and enhances the ergodicity. The highly <001>-textured BNT−ST−0.03NN ceramics display a pure ergodic relaxor state with coexisted ferroelectric Rbar 3c and antiferroelectric P4bm polar nanoregions (PNRs) on nanoscale. Moreover, due to the incomplete interdiffusion between the NN template and BNT−ST matrix, the textured ceramics present a core-shell structure with the antiferroelectric NN core, and thus the BNT-based matrix owns more Rbar 3c PNRs relative to the homogeneous nontextured samples. The high <001> crystallographic texture and more Rbar 3c PNRs both facilitate the relaxor-to-ferroelectric transition, leading to the low-field-driven high strain, while the ergodic relaxor state ensures a small hysteresis. Furthermore, the d33* value remains high up to 518 pm/V at 100 °C with an ultra-low hysteresis of 6%.

Supercritical Relaxor Nanograined Ferroelectrics for Ultrahigh-Energy-Storage Capacitors.

Supercritical relaxor nanograined ferroelectrics are demonstrated for high-performance dielectric capacitors, showing record-high overall properties of energy density ≈13.1 J cm-3 and field-insensitive efficiency ≈90% at ≈74kV mm-1 and superior charge-discharge performances of high power density ≈700 MW cm-3 , high discharge energy density ≈6.67 J cm-3 , and ultrashort discharge time <40ns at 55kV mm-1 . Ex/in situ transmission electron microscopy, Raman spectroscopy, and synchrotron X-ray diffraction provide clear evidence of the supercritical behavior in (Na,K)(Sb,Nb)O3 -SrZrO3 -(Bi0.5 Na0.5 )ZrO3 ceramics, being achieved by engineering the coexistence of multiple local symmetries within the ergodic relaxor zone. The vanished difference between the ground relaxor state and the high-field supercritical state eliminates polarization hysteresis. The supercritical evolution with electric field enables a highly delayed polarization saturation with continuously increased polarization magnitudes. The results demonstrate that such a design strategy of compositionally induced and field-manipulated supercritical behavior can be generalizable for developing desirable energy-storage dielectrics for applications in ceramic/film capacitors.

Contrasting phenomena of quenching-induced piezoelectric performance in (0.4Na1/2Bi1/2TiO3-0.6BiFeO3)-xBaTiO3 ferroelectrics and relaxors

Na1/2Bi1/2TiO3 (NBT)-based materials are promising lead-free alternatives due to their large electrostrain and stable mechanical quality factor. Nonetheless, the relatively low depolarization temperature (Td) impairs its practical application. Recently, quenching from sintering temperature was adopted to increase Td of NBT-based ceramics. However, the origin of the quenching-induced increase in Td is still debated. In this study, quenching effects in (1-x)(0.4Na1/2Bi1/2TiO3-0.6BiFeO3)-xBaTiO3 ceramics are investigated. With increasing BaTiO3 content, this system transforms from ferroelectric to relaxor state at room temperature, with a criticality at x = 0.07, which exhibits R3c and P4bm coexisted phases. Ferroelectric and relaxor compositions exhibit different responses upon quenching. Upon quenching the ferroelectrics, Td increases from 420 to 580 °C for x = 0.04, but d33 is majorly unaltered. However, upon quenching the relaxors, Td increases marginally, while d33 increases from 62 to 97 pC/N. The correlation between the structural evolution and electrical responses upon quenching ferroelectric and relaxor compositions is explored.

Grain size modulated (Na0.5Bi0.5)0.65Sr0.35TiO3-based ceramics with enhanced energy storage properties

• 0.9NBST-0.1BMS lead-free ceramics with W rec = 6.68 J/cm 3 and η = 89.1 % were designed and fabricated. • Small grain size and high activation energy of grain boundary leads to high breakdown field (405 kV/cm). • The energy storage potential ( W rec /E b ) is up to 0.01649 μC/cm 2 . • Excellent fatigue endurance over 10 5 electrical cycles (the W rec variation is less than 1.5%). Ferroelectric ceramics, as a potential candidate for high-power energy storage capacitors, lies in their excellent recoverable energy storage density ( W rec ) and outstanding efficiency ( η ) in practical applications. Herein, a new type of lead-free ceramics (1- x )(Na 0.5 Bi 0.5 ) 0.65 Sr 0.35 TiO 3 - x BiMg 0.5 Sn 0.5 O 3 or (1- x )NBST- x BMS was prepared with the aim of enhancing the breakdown strength ( E b ) and reducing the energy storage loss through grain refinement. It was found that E b of 0.9NBST-0.1BMS reaches 405 kV/cm due to the reduction in the grain size of ceramic and thus the extremely high ratio of grain boundary resistance to grain resistance. Besides, a remarkable energy-storage performance was obtained, that is, W rec and η are ∼ 6.68 J/cm 3 and 89.1% at 405 kV/cm, respectively, along with excellent stability in terms of frequency, temperature, and fatigue endurance. The outstanding energy-storage performance is resulted from modulating the grain size via doping the moderate content of Bi 3+ and Mg 2+ /Sn 4+ , which is beneficial to increase the breakdown field by increasing resistivity under high electric field while increasing the grain boundary activation energy and promote the formation of a relaxor state at the same time. More importantly, energy storage potential (defined as W rec /E b ) is up to 0.01649 μC/cm 2 , being the highest value reported so far for BNT-based ceramics in energy-storage application. Our results pave the way for practical applications of NBST-based ferroelectric capacitors with excellent energy storage performance.

Piezoelectric, ferroelectric and pyroelectric properties of (100 − x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 ceramics

A series of (100[Formula: see text]Pb(Mg[Formula: see text]Nb[Formula: see text]O[Formula: see text]PbTiO3 (PMN[Formula: see text]PT, [Formula: see text]= 24, 25, 26) ceramics were prepared by solid-state reaction technique using MgNb2O6 precursor. The results of the detailed characterizations reveal that the content of PT has negligible influence on the grain size, and all samples possess the perovskite structure. As the PT content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature. As a result, PMN–[Formula: see text]PT ceramics are endowed with electro-strain of 0.08% at a relatively low electric field of 2 kV/mm, and effective piezoelectric coefficient of 320 pm/V was obtained. Simultaneously, the PMN–[Formula: see text]PT ceramics have exceptional pyroelectric performance, exhibiting a high pyroelectric coefficient [Formula: see text][Formula: see text]5.5 – 6.3 × 10[Formula: see text] C⋅cm[Formula: see text]⋅K[Formula: see text]. This study demonstrates the great potential of PMN–[Formula: see text]PT for piezoelectric and pyroelectric device applications.