Electrostrictive Response Research Articles

Structure and properties of Er3+- modified (Bi0.5Na0.5)0.945Ba0.055TiO3-based lead-free ferroelectric ceramics

Er3+-modified (Bi0.5Na0.5)0.945Ba0.055Ti0.98(Fe0.5Sb0.5)0.02O3 (BNBT-FS) lead-free ferroelectric ceramics with large electrostrain and electrostrictive response were fabricated in our work. Results showed that Er3+-doping induced the destruction of ferroelectric order and significantly enhanced the field-induced strain. For 0.2 mol% modified sample, the unipolar strain reached 0.463 % under the electric field of 80 kV/cm, yielding a large normalized strain d33* (Smax/Emax) of 579 pm/V. For 0.4 mol% modified sample, high electrostrictive effect with temperature-insensitive electrostrictive coefficient Q33 (0.022–0.026 m4/C2 in the temperature range of 25–100°C) was obtained. The large electrostrain and electrostrictive response in the present materials show the great potential of the materials for nonlinear actuators applications.

Electromechanical coupling in alkaline-earth doped-ceria ceramics

Oxygen-deficient cerium oxide ceramics exhibit an anomalously high electromechanical response called giant electrostriction. This feature has been linked to the polarization and reorganization of ionic defects, i.e., VO··, under an electric field. However, the exact mechanism and how it is related to intrinsic/extrinsic characteristics of doped ceria remains unclear. The present work investigates how alkaline-earth dopants with different defect–dopant interactions affect the overall electrochemical properties and defect chemistry and, ultimately, how these features impact the final electromechanical properties. We found higher dopant–defect associations attenuate the low-frequency relaxation of the electrostrictive coefficient. The defect chemistry is shown to be the main factor controlling the final electromechanical properties rather than defect concentration. All compositions show a similar electrostrictive response at high frequencies, indicating a common underlying mechanism. All samples showed a high electrostrictive coefficient (up to 3·10−17 m2/V2) and pseudo-piezoelectric response (32 pm/V).

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.

Optical manipulation of the charge-density-wave state in RbV3Sb5.

Broken time-reversal symmetry in the absence of spin order indicates the presence of unusual phases such as orbital magnetism and loop currents1-4. The recently discovered kagome superconductors AV3Sb5 (where A is K, Rb or Cs)5,6 display an exotic charge-density-wave (CDW) state andhave emerged as astrong candidate for materialshosting a loop currentphase. The idea that the CDW breaks time-reversal symmetry7-14 is, however, being intensely debated due to conflicting experimental data15-17. Here we use laser-coupled scanning tunnelling microscopy to study RbV3Sb5. By applying linearly polarized light along high-symmetry directions, we show that the relative intensities of the CDW peaks can be reversibly switched, implying a substantial electro-striction response, indicative of strong nonlinear electron-phonon coupling. A similar CDW intensity switching is observed with perpendicular magnetic fields, which implies an unusual piezo-magnetic response that, in turn, requires time-reversal symmetry breaking. We show that the simplest CDW that satisfies these constraints is an out-of-phase combination of bond charge order and loop currents that we dub a congruent CDW flux phase. Our laser scanning tunnelling microscopy data open the door to the possibility of dynamic optical control of complex quantum phenomenon in correlated materials.

Giant electrostriction in bulk RE (III) substituted CeO2: Effect of RE-[formula omitted] interaction and RE concentration

Recent discovery of giant electrostriction in bulk polycrystalline ceramics and thin films of rare earth (RE (III)) substituted ceria (CeO2) driven by electroactive defect complexes and their coordinated elastic response, expands the material spectrum for electrostrain applications beyond the conventional piezoelectric materials. Bulk ceramics provide an ideal platform to systematically study electrostriction as a function of parameters such as RE3+-defect (VO••) interaction and RE concentration. In this work, we perform structure-property correlation studies in bulk ceramics of RE3+ substituted ceria (RECO) with RE=Y, La and Gd, all of them having weak dopant-defect interaction, with Y- VO•• being attractive, La-VO•• being repulsive, and Gd-VO•• being neutral. We employ large signal measurements to measure the electrostrictive coefficients of all the RECO ceramics, with varying concentration of RE3+, and show that an attractive defect-dopant interaction with atleast 20% of substituent ion concentration yields both giant M and Q electrostrictive response.

Enhanced Mechanical and Electromechanical Properties of Compositionally Complex Zirconia Zr1-x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2-δ Ceramics.

Compositionally complex oxides (CCOs) or high-entropy oxides (HEOs) are new multielement oxides with unexplored physical and functional properties. In this work, we report fluorite structure-derived compositionally complex zirconia with composition Zr1-x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2-δ (x = 0.1 and 0.2) synthesized in solid-state reaction route and sintered via hot pressing at 1350 °C. We explore the evolution of these oxides' structural, microstructural, mechanical, electrical, and electromechanical properties regarding phase separation and sintering mechanisms. Highly dense ceramics are achieved by bimodal mass diffusion, composing nanometric tetragonal and micrometric cubic grains microstructure. The material exhibits an anomalously large electrostriction response exceeding the M33 value of 10-17 m2/V2 at room temperature and viscoelastic properties of primary creep in nanoindentation measurement under fast loading. These findings are strikingly similar to those reported for doped ceria and bismuth oxide derivates, highlighting the presence of a large concentration of point defects linked to structural distortion and anelastic behavior, which are characteristics of nonclassical ionic electrostrictors.

X-ray-induced piezoresponse during X-ray photon correlation spectroscopy of PbMg1/3Nb2/3O3.

X-ray photon correlation spectroscopy (XPCS) holds strong promise for observing atomic-scale dynamics in materials, both at equilibrium and during non-equilibrium transitions. Here an in situ XPCS study of the relaxor ferroelectric PbMg1/3Nb2/3O3 (PMN) is reported. A weak applied AC electric field generates strong response in the speckle of the diffuse scattering from the polar nanodomains, which is captured using the two-time correlation function. Correlated motions of the Bragg peak are also observed, which indicate dynamic tilting of the illuminated volume. This tilting quantitatively accounts for the observed two-time speckle correlations. The magnitude of the tilting would not be expected solely from the modest applied field, since PMN is an electrostrictive material with no linear strain response to the field. A model is developed based on non-uniform static charging of the illuminated surface spot by the incident micrometre-scale X-ray beam and the electrostrictive material response to the combination of static and dynamic fields. The model qualitatively explains the direction and magnitude of the observed tilting, and predicts that X-ray-induced piezoresponse could be an important factor in correctly interpreting results from XPCS and nanodiffraction studies of other insulating materials under applied AC field or varying X-ray illumination.

Non-classical electrostriction in calcium-doped cerium oxide ceramics

Oxygen-defective metal oxides, e.g., acceptor-doped CeO2, demonstrate exceptionally large electrostrictive responses compared to state-of-the-art electromechanically active ceramic materials.

Large electrostrictive response via tailoring ergodic relaxor state in Bi1/2Na1/2TiO3-based ceramics with Bi(Mn1/2Ce1/2)O3 end-member

Lead-free Bi1/2Na1/2TiO3 (BNT)-based relaxor ferroelectric ceramics with superior electrostrictive coefficient features have recently gained a lot of attention due to their application in high-precision displacement actuators. In this work, we propose an effective approach to enhance the electrostrictive effect via tuning the phase transition temperature around ambient temperature in BNT-based ceramics. Herein, a novel Bi(Mn1/2Ce1/2)O3 (BMnCe) modifier was adopted as an activator into 0.935Bi1/2Na1/2TiO3-0.065BaTiO3 (0.935BNT-0.065BT) for modifying the phase boundary (TF-R) around the ambient temperature. The compositional and temperature-dependent dielectric, ferroelectric, and electrostrain were systematically investigated. All samples exhibit a pure perovskite structure. Rietveld refinement revealed that the 0.935BNT-0.065BT ceramic presents a coexistence of rhombohedral (R3c) and tetragonal (P4bm) phases. As the BMnCe content increases, the tetragonal (P4bm) phase becomes more prevalent and eventually shifts into a pseudocubic phase. It was found that the addition of BMnCe can effectively tune the TF-R below ambient temperature and enhance the relaxor behavior. The polarization and electrostrain analysis revealed that the ferroelectric long-range order decreases with increasing BMnCe; specifically, a unique region emerges where remnant polarization, quasistatic d33, and negative strain abruptly drop. As a result, a high electrostrain (S) of 0.43 % with a normalized strain (Smax/Emax) of 716 pm/V was achieved at the critical composition (0.01 M concentration of BMnCe). More importantly, (0.935-x)BNT-0.065BT-xBMnCe (x = 0.01) shows a large electrostrictive coefficient (Q33) of 0.032 m4/C2 with a giant normalized electrostrictive coefficient (Q33/E) of 5.33ｘ10−9 m5/C2V at room temperature. Furthermore, the Q33 and Q33/E values show temperature insensitivity up to 120 °C, rendering the compound suitable for actuation-based devices. These results offer an effective avenue for designing high-performance BNT-based materials with giant electrostrictive coefficients.

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.

Ultrahigh electrostrictive coefficient and hysteresis-free electrostrictive strain in textured BCZT ceramic

Precision-controlled systems necessitate electronic actuators with large displacement, high precision, and miniaturization. Therefore, advanced ferroelectric functional ceramic materials must exhibit substantial displacement responsiveness, minimal hysteresis, and performance stability. Modifying electrostrictive ceramics to enhance the electrostrictive coefficient (Q33) through conventional doping strategies has proven challenging. To address this, grain-oriented textured ceramics harness crystalline anisotropy to elevate Q33 and electrostrictive strain response. In this work, we employ the template grain growth (TGG) method integrating preprepared BaTiO3 (BT) microtemplates, to cultivate <001>-oriented 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) ceramics. Remarkably, the <001>-oriented BCZT ceramic manifests a substantial Q33 value of 0.066 m4/C2, marking a 65 % increase compared to randomly oriented ceramics. Under 100 kV/cm, ultra-high electrostrictive strain response (0.23%) and minimal hysteresis (1−8%) were achieved. Crucially, this elevated Q33 remains thermally stable within the range of 20−100 °C. This advancement not only enables the production of electrostrictive ceramics with improved Q33 and hysteresis-free strain but also broadens the application horizon of BCZT-based electrostrictive ceramics within high-precision actuator technologies.

Nonlinear model order reduction of resonant piezoelectric micro-actuators: An invariant manifold approach

This paper presents a novel derivation of the direct parametrisation method for invariant manifolds able to build simulation-free reduced-order models for nonlinear piezoelectric structures, with a particular emphasis on applications to Micro Electro Mechanical Systems. The constitutive model adopted accounts for the hysteretic and electrostrictive response of the piezoelectric material by resorting to the Landau-Devonshire theory of ferroelectrics. Results are validated with full-order simulations operated with a harmonic balance finite element method to highlight the reliability of the proposed reduction procedure. Numerical results show a remarkable gain in terms of computing time as a result of the dimensionality reduction process over low dimensional invariant sets. Results are also compared with experimental data to highlight the remarkable benefits of the proposed model order reduction technique.

Generalized relation between electromechanical responses at fixed voltage and fixed electric field

We present a general relation between the electromechanical couplings of infinitesimal strain and electric field to arbitrary order, measured at fixed voltage and at fixed electric field. We show that the improper response at fixed field can be written as the strain derivative of the $n^{\text{th}}$ order susceptibility tensor, and the proper response at fixed voltage drop can be written as the response at fixed field plus corrections for dilations and 90$^{\circ}$ rotations induced by strain. Our theory correctly reproduces the proper piezoelectric response and we go beyond with the electrostrictive response. We present first-principles calculations of the improper electrostrictive response at fixed field, and illustrate how the correction is used to obtain the proper response at fixed voltage. This distinction is of high importance given the recent interest in giant electrostrictors exhibiting electromechanical responses as large as the piezoelectric ones.

Defects in poly(vinylidene fluoride)-based ferroelectric polymers from a molecular perspective

As the most intensively investigated ferroelectric polymers, poly(vinylidene fluoride) and its co-/ter-polymers enable major breakthroughs in a wide range of applications. Since defects play a vital role in tuning a spectrum of physical properties of poly(vinylidene fluoride)-based ferroelectric polymers, defect engineering has become an ingenious and robust strategy in the design of high-performance ferroelectric polymers. In this Review, we summarize the physical insights into the role of defects induced by various monomers at the molecular level on the physical properties and the structure–property relationship of defect-modified ferroelectric polymers. We focus on the fundamentals of the different structural defects on tailoring the dielectric, ferroelectric, electromechanical, and electrocaloric properties, along with the device performance enhancement in capacitors, actuators, and solid-state cooling. The influence of defects on the electric field dependence of the electrostriction and electrocaloric response is highlighted. The role of chiral defects in driving the emergent relaxor properties and morphotropic phase boundary behavior of ferroelectric polymers is discussed. Finally, we offer insightful perspectives on the challenges and opportunities in this rapidly evolving field. The underlying mechanisms revealed in the article are anticipated to guide future fundamental and applied studies of ferroelectric polymers that capitalize on defect engineering for electronic and energy applications.

Strain-engineered divergent electrostriction in KTaO3

We investigate the electrostrictive response across a ferroelectric phase transition from first-principles calculations and show that $M$, the field-induced electrostrictive tensor, controlling the amplitude of the electric-field induced strain, can be made arbitrarily large through strain engineering. We take as a case study the epitaxial strain-induced transition from para- to ferroelectricity of ${\mathrm{KTaO}}_{3}$. We show that the magnitude of the field-induced electrostriction diverges with the permittivity at the transition, hence exhibiting giant responses through a calculation of both the $M$ and $Q$ electrostrictive tensors. We explain the origin of this giant electrostrictive response in ${\mathrm{KTaO}}_{3}$ using a microscopic decomposition of the electrostriction coefficients, and use this understanding to propose design rules for the development of future giant electrostrictors for electromechanical applications. Finally, we introduce a further means to calculate electrostriction, specific to ferroelectrics, and not yet utilized in the literature.

Eu3+-Doped Electrospun Polyvinylidene Fluoride-Hexafluoropropylene/Graphene Oxide Multilayer Composite Nanofiber for the Fabrication of Flexible Pressure Sensors.

The development of flexible materials with higher piezoelectric properties and electrostrictive response is of great significance in many applications such as wearable functional devices, flexible sensors, and actuators. In this study, we report an efficient fabrication strategy to construct a highly sensitive (0.72 kPa–1), red light-emitting flexible pressure sensor using electrospun Eu3+-doped polyvinylidene fluoride–hexafluoropropylene/graphene oxide composite nanofibers using a layer-by-layer technology. The high β-phase concentration (96.3%) was achieved from the Eu3+-doped P(VDF-HFP)/GO nanofibers, leading to a high piezoelectricity of the composite nanofibers. We observed that a pressure sensor is enabled to generate an output voltage of 4.5 V. Furthermore, Eu3+-doped P(VDF-HFP)/GO composite nanofiber-based pressure sensors can also be used as an actuator as it has a good electrostrictive effect. At the same time, the nanofiber membrane has excellent ferroelectric properties and good fluorescence properties. These results indicate that this material has great application potential in the fields of photoluminescent fabrics, flexible sensors, soft actuators, and energy storage devices.

Photoacoustic Enhancement of Ferricyanide-Treated Silver Chalcogenide-Coated Gold Nanorods.

Plasmonic gold nanorods (AuNRs) are often employed as photoacoustic (PA) contrast agents due to their ease of synthesis, functionalization, and biocompatibility. These materials can produce activatable signals in response to a change in optical absorbance intensity or absorbance wavelength. Here, we report a surprising finding: Ag2S/Se-coated AuNRs have a ~40-fold PA enhancement upon addition of an oxidant but with no change in absorption spectra. We then study the mechanism underlying this enhancement. Electron micrographs and absorption spectra show good colloidal stability and retention of the core-shell structure after potassium hexacyanoferrate(III) (HCF) addition, ruling out aggregation and morphology-induced PA enhancement. X-ray diffraction data showed no changes, ruling out crystallographic phase changes upon HCF addition, thus leading to induced PA enhancement. Attenuated total reflectance-Fourier transform infrared spectroscopy and zeta potential analysis suggest that PA enhancement is driven by the irreversible displacement of hexadecyltrimethylammonium bromide with HCF. This is further confirmed using elemental mapping with energy-dispersive X-ray analysis. PA characterization after HCF addition showed a four-fold increase in the Grüneisen parameter (Γ), thus resulting in PA enhancement. The PA enhancement is not seen in uncoated AuNRs or spherical particles. Two possible mechanisms for PA enhancement are proposed: first, the photo-induced redox heating at the Ag2S/Se shell-HCF interface, resulting in an increase in temperature-dependent Γ, and second, an enhanced electrostriction response due to HCF adsorption on a layered plasmonic nanoparticle surface, resulting in a high thermal expansion coefficient (β) that is directly proportional to Γ.

Lead-free (Ba0.88Ca0.12)(Ti0.94Sn0.06)O3 piezoceramics: A comprehensive analysis of the phase evolution and enhancement of electrical properties induced by high energy ball milling

The study reveals that high-energy ball milling can be employed to induce controlled phase evolution in lead-free (Ba0.88Ca0.12)(Ti0.94Sn0.06)O3(BCST) ceramics. These piezoceramics were fabricated through solid-state sintering route using nanopowders produced by high-energy milling over durations varying from 5 to 30 h. Rietveld refinements confirm the co-existence of orthorhombic (O)-tetragonal (T) phases in the ceramics with their relative proportions systematically changing with the milling duration. The milling technique demonstrates its capability of enhancing the Curie temperature (Tc) appreciably –BCST's low Tc being a serious drawback for not making it a strong contender for replacing widely used PZT in piezoelectric industry. Additionally, the study shows the possibility of enhancing the high pyroelectric coefficient value by 260% and electrostrictive response to as high as 0.048 m4C-2 by only mechanical milling without any change in the ceramic composition. These observed values of pyroelectric and electrostrictive responses are much higher than even those of Pb-based materials.

Structure, dielectric, electrostrictive and electrocaloric properties of environmentally friendly Bi-substituted BCZT ferroelectric ceramics

In this study, environmentally friendly Bi-substituted [(Ba0.85Ca0.15)1-3x/2Bix](Zr0.1Ti0.9)O3 (BCZT-xBi) ferroelectric ceramics with x = 0–0.08 were prepared using a solid-state sintering method. The structures, dielectric, electrostrictive and electrocaloric properties of the Bi-substituted BCZT ceramics were thoroughly investigated. With an increase in the Bi3+ content, the temperature corresponding to the maximum permittivity (Tm) decreased monotonously. Meanwhile, the broadening of the dielectric peaks and the increase in the relaxation coefficient of the ceramics transformed their typical ferroelectric-to-paraelectric phase transition to diffuse phase transition (DPT). This was further confirmed by the trends shown by the ferroelectric properties of the ceramics. The current peak intensity in current-electric field (I-E) curves decreased with an increase in x and finally became constant, indicating that domain reversal disappeared gradually. High electrostrictive coefficient Q33 values of 0.0307, 0.0299 and 0.0223 m4/C2 were obtained for the ceramics with x = 0.02, 0.04 and 0.06 respectively. The Q33 values of the ceramics indicated their temperature-insensitive nature over the temperature range of 30–120 °C. Although the maximum value of the electrocaloric adiabatic temperature change (ΔT) (0.91 K) was achieved at x = 0.02, the thermally stability of ΔT is improved with an increase in x from 0.02 to 0.06. The results indicated that x = 0.06 improved the thermal stability of the electrostrictive and electrocaloric performance. By increasing the driving field strength, better electrostrictive and electrocaloric responses could be achieved.

Enhanced electric field-induced strain and electrostrictive response of lead-free BaTiO3-modified Bi0.5(Na0.80K0.20)0.5TiO3 piezoelectric ceramics

ABSTRACT Lead-free (1-x)Bi0.5(Na0.80K0.20)0.5TiO3-xBaTiO3 or (1-x)BNKT-xBT (x = 0 – 0.15 mol fraction) piezoelectric ceramics have been investigated. The optimum density was found for the ceramic sintered at 1125°C, corresponding 98 – 99% of their theoretical values. All ceramics had a single perovskite structure. The coexisting mixed tetragonal-rhombohedral phases all over the entire compositional range with tetragonal phase becoming superior at higher BT. The diffuse phase transition was promoted by the addition of BT. With increasing BT content, the Tm and Td values were found to decrease. Phase transition from ferroelectric (FE) phase to ergodic relaxor (ER) phase was also induced by the changes in BT content. These changes significantly suspended long-range ferroelectric order, then correspondingly reducing the Pr and Ec , resulting in an improvement of electrostrictive and electric field-induced strain responses. A significant increasing of electric field-induced strain response (Smax = 0.37% and d*33 = 630 pm/V) is noted for the x = 0.05 ceramic. Furthermore, high electrostrictive coefficient (Q33 ) of 0.0421 m4/C2 is observed for this composition, which was more than ~ 2 times (~108%) as compared to the pure BNKT ceramic. The studied results indicated these ceramics can be considered promising candidates for actuator applications.