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The electron transport characteristics of magnetic and non-magnetic ferroelectric tunnel junctions based on Hf 0.5 Zr 0.5 O 2 are investigated in this study. A modified linear approach to the Thomas–Fermi interfacial screening model is employed to simulate these properties. This method is developed by leveraging the quantum approximation of the quasiclassical spin-resolved point-like contact formalism. The oxygen vacancies, voltage-induced screening, and electrostriction effect are the key phenomena exploited to build the potential profile and hence to simulate the resistive switching characteristics of the ferroelectric tunnel junctions. To validate its precision, the model is extensively verified with experimental data. The obtained model is generalized to reproduce mono-domain and multi-domain ferroelectric switching, featuring its effectiveness for non-volatile storage devices and ferroelectric-field effect transistors. [ABSTRACT FROM AUTHOR]

Piezoceramics with large strain output, low hysteresis, and wide operation temperature are indispensable for the high‐end displacement control. Unfortunately, requiring these merits simultaneously remains a long‐standing challenge for lead‐free piezoceramics promising for replacing lead‐based ones. Herein a new strategy to resolve this challenge by developing modified re‐entrant‐like potassium sodium niobate ((K, Na)NbO3, KNN) relaxors is presented. Multi‐scale structural analysis reveals the presence of the significant local disorder, nano‐sized multi‐phase coexistence, and ultra‐fine grains, which facilitate the polarization rotation, effectively eliminate non‐180° domains, and erase polymorphic phase transition features in re‐entrant‐like KNN relaxors. Consequently, a combination of large strain (≈0.19%), ultra‐low hysteresis (<7%), high electrostriction coefficient (Q33 = 0.049 m4 C−2), and benign temperature stability (i.e., strain varies less than 10.6% within 30–120 °C) is realized, superior to other lead‐free relaxors. Therefore, this strategy provides a novel paradigm for designing high‐performance lead‐free piezoceramics used for high‐precision actuators. [ABSTRACT FROM AUTHOR]

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Electrostrictive materials exhibit a strain that is proportional to the square of the induced polarization. In linear dielectrics where the permittivity is constant, this electromechanical strain is also proportional to the square of the electric field. However, under increasing amplitudes of the driving field, the electromechanical strain sometimes saturates; the electrostrictive coefficients therefore appear to depend on the amplitude of the electric field used to measure them. Here, a methodology showing that this apparent field dependence is a consequence of neglecting higher‐order electromechanical phenomena is presented. When these are taken into account, not only do the electrostrictive coefficients remain constant but the signs of the high‐order coefficients enable the prediction of the saturation behavior from a single measurement. This approach is illustrated on both classical and non‐classical (so‐called "giant") electrostrictors. [ABSTRACT FROM AUTHOR]

In this work, [001] textured Sm0.025Pb0.9625(Mg1/3Nb2/3)0.74Ti0.26O3 (Sm-PMN-26PT) ceramics were synthesized by the templated grain growth method. The dielectric, piezoelectric, and electromechanical properties of untextured and textured ceramics are systematically studied. A high texture degree of 99% was obtained using 1% volume fraction of the BaTiO3 (BT) template. The textured ceramics exhibit an excellent piezoelectric coefficient d33 of 1882 pC/N at room temperature, and an extremely high d33* of 2510 pm/V is obtained. The dielectric, ferroelectric, and strain characteristics reveal that the improvement of piezoelectric properties of textured ceramics comes from the increase of dielectric constant ε33 and electrostriction coefficient Q33. Both the intrinsic response of the domain and the external contribution of the domain wall are enhanced in [001] textured ceramics, which may be the microscopic mechanism of increased piezoelectric activity. The Sm-PMN-26PT textured ceramics exhibit excellent piezoelectric properties, which are very promising for using at room temperature. [ABSTRACT FROM AUTHOR]

The critical frequency and the relaxation time are analyzed through deformation and displacement during electrostriction which is induced by the electrical field at different frequencies. First, when the frequency is 50 Hz and the field strength is 2.5 kV mm−1, the electrostrictive displacement of polyethylene is 6.72 × 10−4 mm. After the data fitting, it is found that the displacement increases linearly with the square of field strength and that the proportional coefficient of 50 Hz is 1.08 × 10−4. Second, due to the influence of relaxation polarization and power loss, with the increase of frequency, the displacement and the proportional coefficient first increases then decreases, and when the frequency is 10 kHz, the displacement of 2.20 × 10−6 mm and the proportional coefficient of 3.51 × 10−7 have minimum values, which are 99.67% and 99.68% lower than that of 50 Hz, respectively. There is the critical frequency. Finally, based on the characteristic of anomalous dispersion, the relaxation time of polyethylene is 9.19 × 10−6s, which is in the time range of thermionic relaxation polarization and consistent with the actual situation. This analysis confirms the quantitative relationship between electrostrictive characteristics, field strength, and polarization. In addition, the relationship between frequency and strain is discussed, and the critical frequency in polymer and the relaxation time are confirmed. [ABSTRACT FROM AUTHOR]

Sintering for large‐sized, stoichiometric Bi0.5Na0.5TiO3 (BNT) ceramics is of great challenge due to the loss of volatile Bi/Na at A‐site of perovskite structure. In this work, BNT ceramic tile with the size of ∼10 × 10 cm2 and near‐stoichiometric composition has been successfully fabricated by Isobam‐assisted gelcasting process, followed by sintering with 1150°C calcined power bed. The powder bed used and sintering duration were found to have a great influence on the formation of the Na‐deficient phase (Bi4.5Na0.5Ti4O15) in the ceramics, and the strategies to eliminate it have been explored. The obtained ceramics exhibit a dielectric constant/loss of 673.6/0.039 at 1 kHz, as well as an electrostrictive strain of ∼0.07% which corresponds to a converse piezoelectric constant d33∗$d_{33}^*$ of 105.2 pm/V. Our work thus provides an effective approach to prepare large‐sized and stoichiometric BNT ceramics. [ABSTRACT FROM AUTHOR]

Abstract Despite extensive research on piezoelectric polymers since the discovery of piezoelectric poly(vinylidene fluoride) (PVDF) in 1969, the fundamental physics of polymer piezoelectricity has remained elusive. Based on the classic principle of piezoelectricity, polymer piezoelectricity should originate from the polar crystalline phase. Surprisingly, the crystal contribution to the piezoelectric strain coefficient d31 is determined to be less than 10%, primarily owing to the difficulty in changing the molecular bond lengths and bond angles. Instead, >85% contribution is from Poisson's ratio, which is closely related to the oriented amorphous fraction (OAF) in uniaxially stretched films of semicrystalline ferroelectric (FE) polymers. In this perspective, the semicrystalline structure–piezoelectric property relationship is revealed using PVDF‐based FE polymers as a model system. In melt‐processed FE polymers, the OAF is often present and links the crystalline lamellae to the isotropic amorphous fraction. Molecular dynamics simulations demonstrate that the electrostrictive conformation transformation of the OAF chains induces a polarization change upon the application of either a stress (the direct piezoelectric effect) or an electric field (the converse piezoelectric effect). Meanwhile, relaxor‐like secondary crystals in OAF (SCOAF), which are favored to grow in the extended‐chain crystal (ECC) structure, can further enhance the piezoelectricity. However, the ECC structure is difficult to achieve in PVDF homopolymers without high‐pressure crystallization. We have discovered that high‐power ultrasonication can effectively induce SCOAF in PVDF homopolymers to improve its piezoelectric performance. Finally, we envision that the electrostrictive OAF mechanism should also be applicable for other FE polymers such as odd‐numbered nylons and piezoelectric biopolymers.

With the rapid development of optoelectronic technology, the realization of multi-functional properties of ferroelectrics has recently become a hot research topic. In the present study, a high electrostrictive effect and excellent photoluminescence properties have been achieved by introducing rare earth Er3+ ions into the high-performance 0.96(K 0.48 Na 0.52)(Nb 0.95 Sb 0.05)O 3 -0.04Bi 0.5 (Na 0.82 K 0.18) 0.5 ZrO 3 (0.96KNNS-0.04BNKZ) ferroelectric ceramic. As a result of the Er3+ doping, the ferroelectric long-range order of 0.96KNNS-0.04BNKZ was disrupted, which led to the formation of polar nanoregions and electrostriction enhancement. The sample that was doped with 0.8 mol% Er3+ ions showed a high electrostrictive strain of ∼0.11 % (at 80 kV/cm), with a large electrostrictive coefficient, Q 33, of 0.033 m4/C2. Q 33 was not sensitive to either a temperature change or field cycling. In addition, the Er3+-modified samples showed a bright up-conversion photoluminescence with a strong green emission, which could be explained by the presence of Er3+ activator ions. Furthermore, an excellent optical temperature performance, with a sensitivity of S = 0.0075 K−1 at 570 K, was achieved for the ceramic that was doped with 0.1 mol% Er3+. This sensitivity was higher than for most rare earth-doped ferroelectric materials. Because of these excellent optical and electrical characteristics, the Er3+-doped 0.96KNNS-0.04BNKZ-based ferroelectrics demonstrated promising prospects for applications in optical-electrically integrated and coupling devices. [ABSTRACT FROM AUTHOR]

Photostrictive materials have attracted tremendous interest as the new generation of smart materials that can achieve a direct conversion from optical energy to mechanical energy. Understanding their nonlinear mechanical properties under light illumination is of paramount significance for their realistic optomechanical applications. This article proposes a novel opto-electro-thermo-elastic constitutive model that can consider the effects of photostriction, photothermal temperature, and electrostriction for metal halide perovskite crystals and investigates the nonlinear static and dynamic responses of the perovskite plates. The nonlinear governing equations are established based on the first-order shear deformation theory and von Kármán nonlinearity and are numerically solved by the differential quadrature method. A detailed parametric investigation is performed to analyze the effects of light and electricity on the nonlinear mechanical behaviors of perovskite plates. It is concluded that light illumination leads to the presence of optical stress and thermal stress in the perovskite plates, giving rise to increased static and dynamic deformations and stresses, as well as reduced postbuckling and free vibration characteristics. The research findings pave the way for the optomechanical applications of perovskite-based smart materials and structures. [ABSTRACT FROM AUTHOR]

The interaction of localized light with matter generates optical electrostriction within dielectric fluids, leading to a discernible change in the refractive index of the medium according to the excitation's light profile. This optical force holds critical significance in optical manipulation and plays a fundamental role in numerous photonic applications. In this study, we demonstrate the applicability of the pump-probe, photo-induced lensing (PIL) method to investigate optical electrostriction in various dielectric liquids. Notably, the thermal and nonlinear effects are observed to be temporally decoupled from the electrostriction effects, facilitating isolated observation of the latter. Our findings provide a comprehensive explanation of optical forces in the context of the recently introduced microscopic Ampère electromagnetic formalism, which is grounded in the dipolar approximation of electromagnetic sources within matter and characterizes electrostriction as an electromagnetic-induced stress within the medium. Here, the optical force density is re-obtained through a new Lagrangian approach. [ABSTRACT FROM AUTHOR]

Sr2+ modified perovskite-type polycrystalline BaTi0.9Zr0.1O3 ferroelectric ceramic exhibits high potential to engage in piezoelectric or high energy density storage applications. In this study, the structural, microstructural, electrical, ferroelectric and piezoelectric behaviours have been investigated in detail. The developed material crystallizes in tetragonal phase with a decrease in lattice parameter by substituting Sr2+ ion in the A site. Each composition shows a diffused phase transition, which is a characteristic of the relaxor phase. A significant decrease in phase transition temperature from 99.8°C for x = 0.00 to 50.9°C for x = 0.20 is observed. The large energy density storage capacity for composition x = 0.10 with Wrec ~ 62.18 mJ cm–3 has been observed at a low field, but maximum efficiency η = ~81.46% is observed for x = 0.20. The Sr2+ doped composition with x = 0.10 shows good piezoelectric strain = 0.029% with a small hysteresis loss in S–E curve, which makes it suitable for piezoelectric application. The significantly high electrostrictive coefficient Q11 = 0.078 m4 C–2 is observed for composition x = 0.15. [ABSTRACT FROM AUTHOR]

The recent discovery of "giant" electrostrictors has re-ignited the interest in electrostriction, an electromechanical coupling existing in all dielectrics but overshadowed by its linear counterpart: piezoelectricity. In this Review, after a reminder of "classical" electrostriction, we propose a definition of "giant" electrostriction based on two empirical relations ("Newnham" relation and the one we posit). From this definition, we review previous reports on "giant" electrostrictors to assess their nature. Focusing on the ones satisfying our definition, we compare their performances and characteristics. We also identify some of the hurdles to overcome before their adoption in the wide range of electromechanical applications, despite their fundamental and applicative interests. [ABSTRACT FROM AUTHOR]

Electrocaloric (EC) cooling has the potential to be an alternative to traditional cooling methods. The polyvinylidene fluoride-trifluoro ethylene-chlorofluoroethylene terpolymer (P(VDF-TrFE-CFE) is used as electrocaloric material. A 3D equation-based modeling and finite element simulations are performed for EC cooling, where the battery's heat generation is considered a heat source for analysis. The electric field waveform has been varied to obtain the maximum possible ECE. Electric field cycles with 0.3 sec holding provide the maximum EC temperature change. The magnitude of the electric field is also varied and a maximum adiabatic temperature change of 5.41 K is achieved under 100 MV/m. The EC effect shows that the heat transfer from the source (battery surface) to the sink (environment) is faster than without EC. [ABSTRACT FROM AUTHOR]

Na0.875Ba0.125Nb0.875Ti0.125O3 (NNBT) and Na0.875Ba0.11Bi0.01Nb0.875Ti0.11Sn0.0112O3 synthesized by solid-state technique exhibit P4bm symmetry. Dielectric-relaxations for NNBT show a transition to an antiferroelectric state below 449 °C (TC) with a prominent fall in the dielectric constant and the dielectric loss, like parent NaNbO3. Below 175 °C (TF) Ba, Ti-doping induced frequency-independent dielectric peak marks the ferroelectric phase. With 1.5% Bi, Sn-doping in NNBT, the grain size and the density of the ceramic increase. Bi, Sn-doped NNBT exhibits dielectric transitions at TC and a diffused TF but with reduced conductivity. The doped NNBT system presents a high electrostrictive coefficient of ∼0.06 m4/C2. [ABSTRACT FROM AUTHOR]

Design of a projecting‐receiving dual‐purpose transducer is challenging due to the difficulty of synthesizing piezoelectric materials with combinatory "soft" properties (high piezoelectric coefficient d) and "hard" properties (low dielectric loss and high mechanical quality factor Qm). In this study, we provide a different perspective to address this challenge via exploiting single‐crystal‐like electrostriction coefficient Q33 through the fabrication of grain oriented or textured "hard" piezoelectric ceramics. Mn‐doped 0.27Pb(In1/2Nb1/2)O3–0.41Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (Mn:PIN–PMN–PT) piezoelectric ceramics with a high [0 0 1]c texture fraction of 99% were synthesized, which exhibit three times greater piezoelectric properties (d33 ∼ 828 pC/N) than random counterparts (d33 ∼ 251 pC/N), while maintaining low loss (tan δ ∼ 0.5%, Qm = 443). According to the formula d33=2Q33Prε33${d}_{{\mathrm{33}}}{\mathrm{\ = \ 2}}{Q}_{{\mathrm{33}}}\ {P}_{\mathrm{r}}\ {\varepsilon }_{{\mathrm{33}}}$, the large improvement of d33 in textured ceramics is mainly due to a doubling increase in dielectric constant ε33 and Q33 (∼0.057 m4/C2). Notably, the Q33 exhibits remarkable similarity to that of PMN–PT single crystals, further contributing to the enhanced piezoelectric performance of textured ceramics. Phase field model of ferroelectrics was performed to understand the texturing on Q33 and elucidate the underlying mechanism at the domain level. The textured ceramics exhibit excellent combinatory "soft" and "hard" properties, which are the promising materials for developing projecting‐receiving dual‐purpose transducers with high efficiency and high sensitivity. [ABSTRACT FROM AUTHOR]

Electrostrictors, materials developing mechanical strain proportional to the square of the applied electric field, present many advantages for mechanical actuation as they convert electrical energy into mechanical, but not vice versa. Both high relative permittivity and reliance on Pb as the key component in commercial electrostrictors pose serious practical and health problems. Here we describe a low relative permittivity (<250) ceramic, ZrxCe1-xO2 (x < 0.2), that displays electromechanical properties rivaling those of the best performing electrostrictors: longitudinal electrostriction strain coefficient ~10−16 m2/V2; relaxation frequency ≈ a few kHz; and strain ≥0.02%. Combining X-ray absorption spectroscopy, atomic-level modeling and electromechanical measurements, here we show that electrostriction in ZrxCe1-xO2 is enabled by elastic dipoles produced by anharmonic motion of the smaller isovalent dopant (Zr). Unlike the elastic dipoles in aliovalent doped ceria, which are present even in the absence of an applied elastic or electric field, the elastic dipoles in ZrxCe1-xO2 are formed only under applied anisotropic field. The local descriptors of electrostrictive strain, namely, the cation size mismatch and dynamic anharmonicity, are sufficiently versatile to guide future searches in other polycrystalline solids. Electrostrictors are materials that develop mechanical strain proportional to the square of the applied electric field. Here authors report. Zr-doped-Ceria as a new lead-free electrostrictive material with a similar electrostriction coefficient to the best electrostrictor material currently in use. [ABSTRACT FROM AUTHOR]

Pb(Mg1/3Nb2/3)O3 (PMN) relaxors have gained a lot of interest due to their unusual dielectric relaxation and high electrostrictive electrostrain. However, the Tm (temperature associated with maximum permittivity) of PMN is lower than room temperature, which limits their future development of electrostrain and practical applications. In this study, we increased the Tm by incorporating a relaxor ferroelectric (FE) end member Pb(Zn1/3Nb2/3)O3 (PZN) rather than a conventional high Curie temperature FE end member to create (1−x)PMN–xPZN solid solutions with x = 0.2–0.5. Their dielectric, FE, and electrostrain properties were systematically investigated. In x = 0.4 composition, we get a maximum electrostrain of 0.134% and an equivalent piezoelectric coefficient d33∗$d_{33}^*$ of 936 pm/V under a rather small driving field of 5 kV/cm. Furthermore, the electrostrain of the x = 0.5 is greater than 0.1% between 20 and 80°C, indicating its possible applicability in precision displacement actuators. Our findings not only clarify the electrostrain and electrostrictive properties of (1 − x)PMN–xPZN system but also show an innovative way to improve electrostrain properties by constructing relaxor–relaxor type solid solutions that can be applied to other FE systems. [ABSTRACT FROM AUTHOR]

The pulsed electroacoustic (PEA) method is an established method for space charge measurements in polymeric dielectrics. In view of the poorly understood impact of space charge on the electrical resistivity and the dielectric breakdown behavior of ceramics, it is desirable to adapt the PEA technique to these materials. However, this adaption is non-trivial due to the constitutive properties of ceramics, which are, at least in part, very different from that of polymers. This contribution addresses a particular effect related to the electrostrictive properties of ceramics on the theoretical level. It is shown that these properties may cause an inversion of the sign of the sound wave generated by electrical voltage pulses when compared to typical polymers, which may in turn result in an incorrect interpretation of the measurement results. Using this finding, a reinterpretation of previous experimental results suggests that homo charge forms at the cathode in sheets of alumina ceramics subjected to high voltages. [ABSTRACT FROM AUTHOR]

Ultrafast high-temperature sintering (UHS) is an innovative sintering technique that can densify ceramics in a few seconds, dramatically reducing the carbon footprint and firing costs. In this work, the feasibility of applying UHS in Gd-doped ceria (GDC) and GDC-Er-stabilized bismuth oxide (ESB) composite powders was investigated. At high UHS currents (22–24 A), fully dense GDC samples with a large grain size were obtained. Nonetheless, most of the GDC pellets exhibited micro/macro cracks, which were reduced by lowering the sample thickness. Interestingly, the GDC-ESB composite samples exhibit no cracks or fragmentation at all, thanks to ESB as a sintering aid. Thie samples were further characterized from an electrochemical and electromechanical point of view. The GDC-ESB material displays an ionic conductivity value of ∼1.5 × 10−2 S/cm at 600 °C and frequency-stable (0.1–350 Hz) room temperature electrostriction strain coefficient of ∼10−18 (m/V)2.

The electroactive polymer polyvinylidene fluoride (PVDF) has gained much interest in smart materials research with a wide application range for industry and consumer applications due to the low cost, flexibility, chemical resistance, non-toxicity, and light weight. In this work, we present an α-phase PVDF cantilever that exploits electrostriction as the main transducer mechanism for excitation. We realize thin PVDF films with a thickness of ∼190 nm and a low roughness (∼19 nm RMS). Electrostrictive cantilevers need high electric fields to achieve amplitudes comparable to piezoelectric counterparts. At thinner films, lower voltage levels are requested for comparable electric fields, thus making electrostrictive PVDF cantilevers a viable route and subsequently allowing broader use of PVDF in MEMS devices. We use an asymmetric electrode design that has the advantage of shifting the neutral axis out of the PVDF without enhancing cantilever thickness with a supporting device layer. In addition, these devices can be produced by CMOS compatible micromachining techniques. We measured the electrostrictive and piezoelectric actuation signal with laser-Doppler vibrometry and showed the frequency spectrum and curvature of such α-phase PVDF cantilevers. The cantilevers have a curvate of up to 120 m−1 at 1500 kV/cm. We demonstrate that the electrostrictive actuation has a low temperature dependency in the range from 25 up to 130 °C. A typical cantilever exhibits a geometry dependent low spring constant (k ∼ 0.3 N m−1) and a low quality factor (Q ∼ 75) in air. [ABSTRACT FROM AUTHOR]

A lead‐free tetragonal‐phase (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 (BCTZ) micro sheet is prepared by molten‐salt growth method, which exhibits a polarizing behavior of relaxor ferroelectricity and possesses a high dielectric constant (εr) of ~2400. Subsequently, the BCTZ sheet is evenly doped into ferroelectric copolymer P(VDF‐TrFE)55/45 mol% with different mass fractions, and the flexible BCTZ/P(VDF‐TrFE) composite films are prepared using a conventional solution casting process. εr of BCTZ/P(VDF‐TrFE) increases with the mass content of BCTZ, and reaches 23.8 in 20 wt% BCTZ sample. Meanwhile, at a high electrical field of 30 MV/m, the strain and electric field of BCTZ/P(VDF‐TrFE) are in the opposite direction, indicating a negative value of piezoelectric strain coefficient (d33) caused by inverse piezoelectric effect. In addition, d33 of different BCTZ/P(VDF‐TrFE) films are fitted using a strain‐electrical field curve, which firstly increases and then decreases with increases in BCTZ content. As such, a high d33 of −47.3 pC/N is obtained in BCTZ/P(VDF‐TrFE)15/85 wt% film. Thus, this research concerning the inverse piezoelectric effect may provide a reference for designing a piezoelectric composite using in transducers and actuators. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF)‐based polymers demonstrate great potential for applications in flexible and wearable electronics but show low piezoelectric coefficients (e.g., −d33 < 30 pC N−1). The effective improvement for the piezoelectricity of PVDF is achieved by manipulating its semicrystalline structures. However, there is still a debate about which component is the primary contributor to piezoelectricity. Therefore, current methods to improve the piezoelectricity of PVDF can be classified into modulations of the amorphous phase, the crystalline region, and the crystalline–amorphous interface. Here, the basic principles and measurements of piezoelectric coefficients for soft polymers are first discussed. Then, three different categories of structural modulations are reviewed. In each category, the physical understanding and strategies to improve the piezoelectric performance of PVDF are discussed. In particular, the crucial role of the oriented amorphous fraction at the crystalline–amorphous interface in determining the piezoelectricity of PVDF is emphasized. At last, the future development of high performance piezoelectric polymers is outlooked. [ABSTRACT FROM AUTHOR]

Several aspects of physics have been adversely effected by the fact that vapor phase electrochemistry has proved impossible to quantify. By the end of the 19th century, physicists had encountered several strange observations that appeared to involve chemistry. Eventually, it was realized that, in a moist gas, no rate process involving ions is quantifiable since we possess no valid relationship between the concentrations of electrolytes and their thermodynamic activities. There are both technical and societal reasons for this problem. Until both problems have been addressed, no reliable quantitative conclusions can be drawn for any system where ionic electrostriction in a moist gas is important. The most obvious consequences of the missing science are misconceptions concerning naturally contained air plasmas such as ball lightning, tornadic lights, and unpredictable flying objects (UFOs). None of these phenomena violates any known law of physics, but this only becomes clear once the absence of applicable, strictly valid theories is accepted. Fortunately, partial solutions to the problem exist if use is made of qualitative arguments. Using this approach, it can be seen that all the apparently anomalous characteristics of atmospheric plasmas result from a balance between different physical and chemical driving forces. A better understanding of the chemical consequences of electrostriction should have two long-term benefits. One relates to understanding the corrosive properties of high-pressure steam. The other concerns the specific chemical processes that stabilize air plasmas. If stable air plasmas could be simulated, a plentiful supply of carbon-free energy would become available. [ABSTRACT FROM AUTHOR]

[001] textured 0.40BiScO3‐0.60PbTiO3‐0.125 mol%Nb5+ (BS‐60PT‐0.125Nb) high‐temperature piezoelectric ceramics were synthesized using templated grain growth process. A high texture degree F001 of 99% was obtained using 2 vol% BaTiO3 (BT) templates. The piezoelectric charge constant d33 and the unipolar strain under 40 kV cm−1 at room temperature for the textured ceramics are 646 pC N−1 and 0.36%, respectively, which is over two times as those for untextured ceramics (∼243 pC N−1 and 0.17%). The electrostriction Q33 value of the textured sample remarkably increased from 0.034 m4 C−2 to 0.068 m4 C−2 under 30 kV cm−1, showing a twice higher than untextured. Compared with random ceramics, the improvement piezoelectric response of the textured ceramics is primarily attributed to the increase of the dielectric constant εr and electrostriction coefficient Q33 along [001] orientation, which is originating from the anisotropy of piezoelectricity. The BS‐60PT‐0.125Nb textured ceramics have large piezoelectric response and ultrahigh electrostriction with high temperature stability (high depolarization temperature Td of ∼360°C and high Curie temperature Tc of 421°C), showing great potential for the piezoelectric applications at high temperatures. [ABSTRACT FROM AUTHOR]

(1−x)Pb(Mg1/3Nb2/3)‐xPbTiO3 (PMN‐xPT) ceramics with x ranging from 0.1 to 0.3 were synthesized by solid‐state reaction method. X‐ray diffraction, dielectric and ferroelectric property characterizations were systematically investigated. As x rises, the PMN‐xPT transitions from a cubic to a rhombohedral phase, resulting in an enhancement in ferroelectricity. Our findings show that the electrostrain and longitudinal electrostrictive coefficient Q33 both increase and then decrease within a critical region located between the depolarization temperature TFR and Tm (corresponding to the maximum permittivity), demonstrating strong temperature‐dependent characteristics. In x = 0.2, the maximum Q33 of 0.0361 m4/C2 is obtained, and a phase diagram of studied system is built. Our findings not only shed light on the phase evolution in this system but also reveal a strong temperature‐dependent electrostrictive effect that can be used to improve electrostrains in PMN‐based solid solutions if the critical region can be regulated to a suitable temperature region using engineering strategies. [ABSTRACT FROM AUTHOR]

High strain with low hysteresis is crucial for commercial applications in high precision actuators. However, the clear conflict between the high strain and low hysteresis in BNT-based ceramics has long been an obstacle to actual precise actuating or positioning applications. To obtain piezoceramics with high strain and low hysteresis, it is necessary to enhance the electrostrictive effect and develop an ergodic relaxor (ER) and nonergodic relaxor (NR) phase boundary under ambient conditions. In this work, (Co0.5Nb0.5)4+ doped 76Bi0.5Na0.5TiO3-24SrTiO3 (BNST24) relaxors were fabricated using the conventional solid state reaction route. X-ray diffraction patterns revealed the B-site substitution in BNST24 ceramics. By adjusting the (Co0.5Nb0.5)4+ doping in BNST24, we effectively tuned the TNR-ER and Td close to ambient temperature, which contributed to the development of the ergodic relaxor phase and enhanced the electrostrictive effect at ambient temperature. The I-P-E loops and bipolar strain curves verified the gradual evolution from NR to ER states, while the enhanced electrostrictive effect was verified by the nearly linear S-P2 curves and improved electrostrictive coefficient of the BNST24-xCN relaxors. An enhanced strain of 0.34% (d*33 = 483 pm/V) with low hysteresis of 8.9% was simultaneously achieved in the BNST24-0.02CN relaxors. The enhanced strain was mainly attributed to the proximity effect at the ER and NR phase boundary of BNST24-0.02CN, while the improved electrostrictive effect contributed to the reduced strain hysteresis. Our work demonstrates an effective strategy for balancing the paradox of high strain and low hysteresis in piezoceramics. [ABSTRACT FROM AUTHOR]

The technologically important frequency range for the application of electrostrictors and piezoelectrics is tens of Hz to tens of kHz. Sm3+- and Gd3+-doped ceria ceramics, excellent intermediate-temperature ion conductors, have been shown to exhibit very large electrostriction below 1 Hz. Why this is so is still not understood. While optimal design of ceria-based devices requires an in-depth understanding of their mechanical and electromechanical properties, systematic investigation of the influence of dopant size on frequency response is lacking. In this report, the mechanical and electromechanical properties of dense ceria ceramics doped with trivalent lanthanides (RE0.1Ce0.9O1.95, RE = Lu, Yb, Er, Gd, Sm, and Nd) were investigated. Young's, shear, and bulk moduli were obtained from ultrasound pulse echo measurements. Nanoindentation measurements revealed room-temperature creep in all samples as well as the dependence of Young's modulus on the unloading rate. Both are evidence for viscoelastic behavior, in this case anelasticity. For all samples, within the frequency range f = 0.15-150 Hz and electric field E ≤ 0.7 MV/m, the longitudinal electrostriction strain coefficient (|M33|) was 102 to 104-fold larger than expected for classical (Newnham) electrostrictors. However, electrostrictive strain in Er-, Gd-, Sm-, and Nd-doped ceramics exhibited marked frequency relaxation, with the Debye-type characteristic relaxation time τ ≤ 1 s, while for the smallest dopants-Lu and Yb-little change in electrostrictive strain was detected over the complete frequency range studied. We find that only the small, less-studied dopants continue to produce useable electrostrictive strain at the higher frequencies. We suggest that this striking difference in frequency response may be explained by postulating that introduction of a dopant induces two types of polarizable elastic dipoles and that the dopant size determines which of the two will be dominant.

In dielectric materials, due to the flexoelectric effect, a large inhomogeneous deformation can break or significantly alter the inversion symmetry of the material and induce net polarization. Such a phenomenon is distinctive comparing to other forms of electromechanical coupling, such as piezoelectricity and electrostriction, in that it is an intrinsic and universal effect whose strength scales up with the decrease in the sample size. Research works in the past decade indicate that the emergence of flexoelectricity not only provides a new way of realizing electromechanical coupling, but also has impact on multiple fields including smart materials, devices, and even physics. Our objective of this perspective is to briefly introduce the field of flexoelectricity and discuss on its future development. Also, current challenges and ambiguities that may impede the further development of the field are pointed out. Furthermore, our opinions on why flexoelectricity matters and how can we use it in novel ways are presented. [ABSTRACT FROM AUTHOR]

Dielectric ceramics with high recoverable energy storage density (Wrec) and high energy storage efficiency (η) are urgently needed due to their potential application in pulse capacitor devices. However, the low η and breakdown strength (BDS) have produced a bottleneck for achieving high Wrec at high electric field. Here, we introduce Bi(Mg0.5Ti0.5)O3 (BMT) into Ba(Ti0.92Sn0.08)O3 (BTS) matrix to enhance the relaxor character of BTS–xBMT and reduce the electrostrictive strain generated during electric field loading. The enhanced relaxor character is beneficial for increasing the efficiency, whereas the reduced electrostrictive strain is profitable to increase the BDS. Furthermore, the BDS is significantly improved by the polymer viscous rolling process. Finally, the electrostrictive effect was considerably lowered in an optimized BTS–0.1BMT composition. More crucially, a high Wrec of 4.34 J/cm3 was attained accompanied by excellent temperature stability (variation ≤±5% between 30 and 120°C). The current results show that the developed dielectric ceramics can be used in pulse capacitor devices for energy storage. [ABSTRACT FROM AUTHOR]

This work was done to synthesize tetrazole dye and Z-scan measurement of the synthesized tetrazole compounds has been carried out and interesting results about the origin of positive nonlinear absorption coefficients of dye molecules were obtained. Investigation of linear optical properties of synthesized dyes was done with the help of visible UV absorption, and fluorescence emission spectrum. Also, the electronic characteristics and molecular geometry of the sensitizers were optimized using density functional theory (DFT), and the influence of dye structure on their nonlinear optical performances was studied. Four new dyes with D–π–A architecture were discussed, in which diphenylamine and carbazole units act as donors, methine groups act as conjugated bridge units, and tetrazole derivatives act as acceptor units. Diphenylamine, carbazole, methine, and tetrazole derivatives are, respectively, donor, conjugate, and bridge acceptor units in the structure of these dyes. Moreover, nonlinear absorption and refractive indexes of the synthesized tetrazole components were measured using the Z-scan technique equipped with a 50 mW CW Nd-Yag laser. The nonlinear absorption coefficient of tetrazole derivations was obtained and was positive, and it was demonstrated that the origin of the so-called reverse saturation absorption of dye molecules in low intensities is the electrostriction effect which is due to polarization of the molecules which has an inverse relation with the Homo–Lumo energy gap of the components. [ABSTRACT FROM AUTHOR]

One of the emerging solid-state refrigeration technologies to replace classic compression refrigeration is electrocaloric refrigeration, which has the advantages of high energy conversion efficiency, easy miniaturization, eco-friendliness, and low cost. In this paper, Ba(Ti 1− x Sn x)O 3 (BTSn) ceramics with x = 0.02–0.08 were prepared by a solid-state reaction route. The structural, dielectric, ferroelectric, electrocaloric as well as electrostrictive characteristics were thoroughly examined. Our results show that the dielectric peaks correlated to the maximal permittivity move towards to low temperature direction when the Sn4+ concentration gradually increases, and a phase diagram of BTSn based on the dielectric characteristics is given. More importantly, in the x = 0.04 ceramic sample synthesized by the viscous polymer process, a giant adiabatic temperature change (Δ T) of 6.36 K with a temperature range of 25 °C at 200 kV/cm is achieved. Typically flare shape electrostrain curves accompanying with small hysteresis are observed in all studied compositions. The average electrostrictive coefficient Q 33 varies within 0.0257–0.0306 m4/C2 at a temperature region from 30 to 160 °C, indicating temperature-insensitive and composition-insensitive characteristics. This research shows that a significant electrocaloric effect can be achieved in BTSn ceramics through high electric field, and would provide a strategy for boosting the electrocaloric effect in other systems. [ABSTRACT FROM AUTHOR]

Ternary lead-free (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics were successfully fabricated using a conventional solid-state reaction method. The relative densities, crystal structures, dielectric constant, electric field-induced polarization loops, and electric field-induced strain curves of the sintered piezoelectric ceramics were analyzed. All the piezoelectric ceramics were well sintered with a single perovskite structure and a high relative density of ~ 95%. The x-ray diffraction patterns of the (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics indicate a rhombohedral-to-tetragonal phase transition as a function of x. The BaZrO3 addition reduces the ferroelectricity and enhances the piezoelectricity of the (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics. The highest piezoelectric sensor coefficient d33 is observed in the x = 0.01 piezoelectric ceramic, whereas the highest piezoelectric actuator coefficient d33* is found in the x = 0.03 piezoelectric ceramic. Especially, the x = 0.03 piezoelectric ceramic shows a high d33* of 645 pm/V with a small d33* variation of ~ 20% in the temperature range of 25–100°C. The investigated (0.86−x)Bi0.5Na0.5TiO3-0.14Bi0.5K0.5TiO3-xBaZrO3 piezoelectric ceramics have a great potential for the thermal stability lead-free piezoelectric actuator applications. [ABSTRACT FROM AUTHOR]

Electromechanically active ceramic materials, piezoelectrics and electrostrictors, provide the backbone of a variety of consumer technologies. Gd- and Sm-doped ceria are ion conducting ceramics, finding application in fuel cells, oxygen sensors, and, potentially, as memristor materials. While optimal design of ceria-based devices requires a thorough understanding of their mechanical and electromechanical properties, reports of systematic study of the effect of dopant concentration on the electromechanical behavior of ceria-based ceramics are lacking. Here we report the longitudinal electrostriction strain coefficient (M33) of dense RExCe1-xO2-x/2 (x ≤ 0.25) ceramic pellets, where RE = Gd or Sm, measured under ambient conditions as a function of dopant concentration within the frequency range f = 0.15-350 Hz and electric field amplitude E ≤ 0.5 MV/m. For >100 Hz, all ceramic pellets tested, independent of dopant concentration, exhibit longitudinal electrostriction strain coefficient with magnitude on the order of 10-18 m2/V2. The quasi-static (f < 1 Hz) electrostriction strain coefficient for undoped ceria is comparable in magnitude, while introducing 5 mol % Gd or 5 mol % Sm produces an increase in M33 by up to 2 orders of magnitude. For x ≤ 0.1 (Gd)-0.15 (Sm), the Debye-type relaxation time constant (τ) is in the range 60-300 ms. The inverse relationship between dopant concentration and quasi-static electrostrictive strain parallels the anelasticity and ionic conductivity of Gd- and Sm-doped ceria ceramics, indicating that electrostriction is partially governed by ordering of vacancies and changes in local symmetry.

Large electrostrains with high temperature stability and low hysteresis are essential for applications in high-precision actuator devices. However, achieving simultaneously all three of the aforementioned features in ferroelectric ceramics remains a considerable challenge. In this work, we firstly report a high unipolar electrostrain (0.12% at 60 kV/cm) in (1–x)NaNbO3-x[(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3] (NN-xBCZT) ferroelectric polycrystalline ceramics with excellent thermal stability (variation less than 10% in the temperature range of 30–160 °C) and ultra-low hysteresis (

This paper presents a finite element analysis to model and analyze composite laminated beams with distributed piezoelectric actuators attached to the top and bottom surfaces considering nonlinear constitutive equations under a high electric field. The static response is presented for piezoelectric composite laminated beam using higher order electric field nonlinearity to assess the effect of electrostriction and elastostriction coefficient at a high electric field. A finite element approach based on higher-order shear deformation theory is applied for static analysis of composite laminated beams, varying the thickness and orientation of laminates, to verify the nonlinear effect under a high electric field. A good comparison of results is shown with the available results in the literature. The finding of the results highlights the importance of considering elastostriction term along with the electrostriction term in determining the deflection and stresses of the composite laminated beam. [ABSTRACT FROM AUTHOR]

In cases when it is desirable to transport medication through blood vessels, especially when dealing with brain cancer being confronted with the narrow arteries in the brain, the blood–brain barrier makes medical treatment difficult. There is a need of expanding the diameters of the arteries in order to facilitate the transport of medications. Recent research has pointed to various ways to improve this situation; in particular, the use an ultrasound acting on microbubbles in the blood stream has turned out to be a promising option. Here, a different possibility of enlarging the diameters of arteries is discussed, namely to exploit the electrostrictive pressure produced by internal strong, ultrashort and repetitive laser pulses. Each pulse will at first give rise to inward-directed optical forces, and once the pulse terminates, there will be a hydrodynamical bouncing flow in the outward radial direction, giving an outward impulse to the vessel wall. In the absence of friction, a symmetric oscillation picture emerges. Clearly, a supply of repetitive pulses will be needed (at a parametric resonance) to make the effect appreciable. The effect has, to our knowledge, not been discussed before. We give an approximate optical and hydrodynamical theory of it. The calculations indicate promising results for the wall pressure, although experimental work is desirable to demonstrate whether the idea can be useful in practice. Our calculation is made from a general physical perspective that is not necessarily linked to medical applications. [ABSTRACT FROM AUTHOR]

Mechanical antennas based on piezoelectric materials can effectively reduce the size of long wave antennas down to 1/1000 of the wavelength (from km scale to mm level). However, the narrow bandwidth and weak field intensity seriously restrict its practical applications in transmission distance and channel capacity. Here, a mechanical antenna‐based electrostrictive effect of relaxor ferroelectric ceramic (PMN‐PT) is proposed to improve radiation capacity and achieve ultra‐wideband characteristics (10 kHz–1 MHz). Due to the ultra‐high dielectric constant at working temperature and the relationship between the strain and applied field intensity, the proposed antenna gets rid of the dependence on the poled materials and exhibits excellent communication properties beyond traditional mechanical antennas, which are experimentally demonstrated by a practical wireless communication system. Only using a single proposed mechanical antenna with 8 mm diameter and 3 mm thickness, the effective communication with a transmission distance of 200 m can be realized. This design offers a promising way of constructing mechanical antennas for long‐wave communication. [ABSTRACT FROM AUTHOR]

The control of wave propagation based on refraction principles offers unparalleled possibilities as shown by the striking example of optics. This approach is unfortunately limited for water waves as it relies mainly on variations of the liquid depth which, while controlling the wave velocity, also trigger nonlinearities and damping. In this article, we show experimentally that electrostriction allows to implement extensive refraction-based control of water waves in a precise and contactless manner. The setup consists of an electrode under high voltage placed above the grounded conductive water. The waves propagating under the electrode can be slowed down up to approximately half their speed compared to free propagation. We characterize the Snell--Descartes laws of refraction and the total internal reflection for the water waves. We implement emblematic refraction-based devices such as electrically tunable focusing lenses, waveguides without obstacles, and beam splitters based on frustrated internal reflection to perform interference experiments. [ABSTRACT FROM AUTHOR]

Herein, the strain (S) with low hysteresis can be achieved in [Bi0.5(Na0.72K0.18Li0.10)0.5]0.995Sr0.005(Ti0.995Ta0.005)O3-BaZrO3-NaNbO3 ceramics by an electrostrictive effect, and an excellent electrostrictive coefficient (Q33) of ∼0.037 m4/C2 can be obtained under an electric field of 60 kV/cm. The enhancement of the degree of diffuseness regulated by phase compositions can effectively promote the electrostrictive response and increase the Q33 value. A higher ratio of P4bm and a larger Ps in P4bm guarantee the good linear relationship between S and P2 (P represents polarization), where a larger Ps (P4bm) can effectively restrict the expression of ferroelectric state with the increase of electric fields (E). Consequently, high Q33 values (0.033–0.037 m4/C2) are nearly independent of the applied electric fields. Although the strain from the electrostrictive effect is not tremendous, the good linear relationship between S and P2 is meaningful to the accurate displacement control in displacement actuators. [ABSTRACT FROM AUTHOR]

We present semi-analytical solutions describing the spatiotemporal distributions of temperature and pressure inside low-absorbing dielectrics excited by tightly focused laser beams. These solutions are compared to measurements in water associated with variations of the local refractive index due to acoustic waves generated by electrostriction, heat deposition, and the Kerr effect at different temperatures. The experimental results exhibited an excellent agreement with the modeling predictions, with electrostriction being the dominant transient effect in the acoustic wave generation. Measurements at 4.0∘C show that the thermoelastic contribution to the optical signal is significantly reduced due to the low thermal expansion coefficient of water at this temperature.