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In water remediation applications ferroelectric materials have been shown wide applicability in catalysis due to their spontaneous polarization. 0.5Ba(Zr 0.2 Ti 0.8)O 3 – 0.5(Ba 0.7 Sr 0.3)TiO 3 (BST-BZT) pellets were examined for piezocatalysis activity by electrode effect. These samples were prepared using traditional solid-state reaction and sintering process. The samples were coated with silver paste using manual brushing resulting in Schottky junction having enhanced surface polarization and dye degradation capability. X-ray diffraction, Field emission scanning electron microscopy (FE SEM), and Raman spectroscopy were performed to confirm the phase, morphology and vibrational modes of prepared samples, respectively. Further, Diffuse reflectance spectra (DRS) and X-Ray Photoelectron spectroscopy (XPS) was done to check absorbance and chemical composition. Piezocatalysis activity on electrode sample was observed under 150W and 40 kHz ultrasonication. Well dried samples showed enhanced dye degradation of 68 %. It could be due to additional charges developed at the interface which act as Schottky junction along with triboelectric phenomenon. This highlights the significant impact of Schottky junction in electrode effect by enhancing the piezocatalytic activity. [ABSTRACT FROM AUTHOR]

The present study elucidates the role of annealing with electric field on lamellar crystalline structure and molecular orientation of polymer chains in ferroelectric copolymer (P(VDF‐TrFE)) and ferroelectric terpolymer (P(VDF‐TrFE‐CFE)) spin‐coated thin films. The ferroelectric polymer thin films annealed under an electric field support the growth of nanostructure with an "edge‐on" lamellar crystalline structure having in‐plane molecular chain orientation. The poled P(VDF‐TrFE) thin films have higher remnant polarization (Pr) ≈6.2 µC cm−2 and saturation polarization (Ps) ≈8.2 µC cm−2 at an applied electric field of 250 MV/m compared to unpoled thin films having Pr ≈4.7 and Ps ≈6.2 µC cm−2. Also, poled P(VDF‐TrFE) thin films show lower coercive field (Ec) ≈94 MV/m compared to an unpoled thin film having Ec ≈105 MV/m. Similarly, poled PVDF‐TrFE‐CFE thin film shows better ferroelectric properties having Pr ≈0.4 and Ps ≈5.7 µC cm−2 at an applied electric field of 200 MV m−1 compared to unpoled thin films having Pr ≈0.4 and Ps ≈4.1 µC cm−2. The storage energy efficiency of unpoled and poled P(VDF‐TrFE‐CFE) thin films is measured to be ≈75% and 80%. Annealing of ferroelectric P(VDF‐TrFE) polymer thin films under an electric field demonstrates improved ferroelectric and electroactive properties. [ABSTRACT FROM AUTHOR]

The bulk photovoltaic effect (BPVE) in ferroelectrics, wherein spontaneous polarization can be reversed within crystals lacking centrosymmetry, encompasses the significant contribution of ferroelectric domain walls (DWs), known as DW‐PVE. Nevertheless, the separation between intrinsic BPVE within the domain and DW‐PVE remains unexplored in 2D ferroelectrics, notwithstanding its significant importance. In this study, sizable crystals of 2D ferroelectric SnS are successfully grown, facilitating a comprehensive yet intricate examination of domain configurations utilizing polarized optical microscopy and piezoresponse force microscopy. By properly selecting the large ferroelectric single domain within SnS crystals, uniform intrinsic BPVE across the domain is unequivocally demonstrated. Furthermore, to further enhance intrinsic BPVE, manipulation of strain poling increased photocurrent, suggesting that locally distributed polarizations due to imperfection introduced in SnS crystals are aligned by strain. These results will offer a new avenue for rigorous comprehension of DW‐PVE in 2D ferroelectrics. [ABSTRACT FROM AUTHOR]

This research article is related to a bismuth oxide‐layered pseudo‐perovskite ferroelectric material and its capabilities in the area of photocatalysis. SrBi4Ti4O15 (SBT) catalyst was prepared via a solid‐state reaction followed by calcination at 950°C sustained over 4 h. X‐ray diffraction, X‐ray photoelectron spectroscopy, bandgap analysis, Raman spectroscopy, and scanning electron microscopy confirmed the successful synthesis of the SBT catalyst. The photocatalysis capability was checked on a methylene blue (MB) model dye. The poling of the SBT catalyst was performed under 2 kV/mm of electric field. The poling of the catalyst material played a crucial role in enhancing the photocatalytic activity. Moreover, the effect of volume (k(v)), initial concentration (k(ic)) of the MB dye, amount of catalyst (k(c)), and intensity (k(i)) of the light were examined and analyzed by the mathematical model. This study suggested that higher intensity and amount of catalyst enhance photocatalytic activity, whereas higher concentration and volume of dye suppress the photocatalytic activity. The amount of catalyst showed the highest effect on the photocatalytic activity. The rate constant is influenced by these factors and the order of influence is k(c) > k(i) > k(v) ≃ k(ic). [ABSTRACT FROM AUTHOR]

The study presents a novel self‐powered ultraviolet (UV) photodetector harnessing both polarization fields and photovoltaic effects, enabling the realization of ultra‐low power, reconfigurable optoelectronic logic gates. The approach is demonstrated on a CuO/BaTiO3 heterojunction photodetector. The behavior of the photodetector is augmented by the poling effect, aligning the internal electric field of the BaTiO3 through the application of a robust external electric field, thereby facilitating the implementation of optoelectronic logic gates. In the unpoled state, the “XOR” and “OR” logic gates operated at voltages of 750 and −500 µV, respectively. However, upon poling up state, the “XOR” logic gate exhibits reduced operation voltage, operating at 500 µV, while the “OR” logic gate implements clarity at −500 µV. In the unpoled state the “AND” logic gate does not operate; however, upon poling in the downward direction, it operated at −500 µV. The achievement demonstrates successful ultra‐low‐power logic operations, utilizing voltages in the hundreds of micron scale, under a 310 nm wavelength and a light intensity of 0.52 mW·cm−2. Furthermore, controllable polarization electric fields in BaTiO3 enable the operation of “AND” logic gate in the unpoled state, presenting a promising avenue for future research in optoelectronic logic gate design. [ABSTRACT FROM AUTHOR]

Compared with powder particles, ceramic block piezocatalyst possesses the advantages of high cycle stability, decreasing secondary pollution, and easy recovery. Herein, with a simple strategy of the poling procedure, the piezocatalytic activity of 0.96K0.5Na0.5NbO3‐0.04Bi0.5Na0.5ZrO3 (abbreviated as 0.96KNN‐0.04BNZ) ceramic blocks can be considerably improved. A reaction rate constant k value of 14.70×10−3 min−1 in the poled sample can be obtained to degrade Rhodamine B, which is 3.44 times that of the unpoled one. Meanwhile, the poled sample also has good degradation effects against methylene blue and amino black 10B. The improvement of piezocatalytic activities originates from the reduction of crystal symmetry and the enhancement of electron‐hole pair separation, which accelerates the generation of charge carriers. This research displays a unique lead‐free bulk piezocatalyst and a convenient method for enhancing its piezocatalytic activity. [ABSTRACT FROM AUTHOR]

Poling parameters and barium titanate (BT) content significantly affect the piezoelectric and dielectric properties of poly(vinylidene fluoride) (PVDF). Selecting the best possible values for these process parameters is indeed a significant challenge. In this study, piezoelectric nanocomposites for high-energy conversion were prepared by mixing PVDF with BT. The dependence of piezoelectric and dielectric properties on process parameters was investigated. The input parameters, including poling temperature, time and voltage, and BT mass fraction, were considered as input variables. A Box-Behnken Design was used to design and analyze the experiments. ANOVA was performed to study the significance of poling parameters and BT mass fraction. An Artificial Neural Network was used to model PVDF-based nanocomposite properties as a function of the four process parameters. A genetic algorithm was applied to search for the optimal poling conditions and BT mass fraction. The optimal combination leads to a d33 coefficient of 25.259 pC/N, a permittivity of 24.282, and a β-phase fraction (F(β)) of 95.435%. These results were experimentally validated, and the errors were 9.789, 0.338, and 0.305%, respectively. Following the optimization, a PVDF-based nanocomposite with excellent piezoelectric and dielectric properties (d33 = 28pC/N, permittivity = 24.2, F(β) = 95.7%) was fabricated for energy conversion applications. [ABSTRACT FROM AUTHOR]

In antiferroelectrics (AFE), the recovery of AFE phase from field‐induced ferroelectric (FEIN) phase occurs at the depolarization temperature, Td. In this study, we report an exceptionally high pyroelectric coefficient, p ≈ 16.00 × 10−2 C/m2 K at ∼70°C in the AFE composition Pb0.982La0.012(Zr0.60Sn0.30Ti0.10)O3 which lies close to FE‐AFE phase boundary. We closely examine this FEIN‐AFE transformation in virgin and poled samples, during heating, by temperature‐dependent X‐ray diffraction, polarization, strain–electric field hysteresis, dielectric and pyroelectric studies and report, for the first time, the mechanism responsible for this behavior. [ABSTRACT FROM AUTHOR]

This article elucidates the field-assisted high-temperature poling effect on the improvement of crystallinity of β-phase structure of the electrospun-deposited PVDF-TrFE nanofiber film. Morphology, crystallinity and their variation/behavior on poling ferroelectric polymer electrospun PVDF-TrFE nanofibers have been investigated thoroughly using FESEM, XRD and Raman spectroscopy. Field-assisted high-temperature poling at 120 °C of PVDF-TrFE nanofiber film generated a condition similar to high mechanical stress which assisted the nucleation and growth kinetics of new β crystals and their reorientation mechanism due to sliding diffusion of ferroelectric polymer chains along the chain axis in the nanofiber. On increasing the poling time duration number of oriented polar crystalline domain regions in deposited nanofiber films rises which resulted in enhancement of crystallinity of films. XRD and Raman analysis complemented the study of enhancement of β-phase crystallinity in as-deposited PVDF-TrFE nanofiber film on poling with no noticeable change in the dimension and morphology of the nanofibers. Further, enhancement of ferroelectric property of the poled nanofiber film has been observed with increase of poling time which supports our interpretation of poling facilitated nucleation and growth kinetics of new β-crystal with long trans-sequences in deposited nanofiber films. [ABSTRACT FROM AUTHOR]

Aging in dielectrics manifests as a reduction in capacitance over time owing to the applied electric field. This study revisits the aging mechanism in multi-layer ceramic capacitors (MLCCs), specifically considering DC-bias voltage and temperature variables. The findings indicate that aging is intensified by higher DC-bias voltages (electric field strength) and elevated temperatures, ultimately leading to capacitance saturation. A poling–depoling experiment confirms the rapid assessment of saturation capacitance. Consequently, we propose a straightforward method involving electric field manipulation to quantitatively evaluate the saturated capacitance of MLCCs under aging conditions. The estimated capacitance aligns closely with the measured capacitance after 2000 h, with an error rate not exceeding 4 %. [ABSTRACT FROM AUTHOR]

Piezoelectric paints/coatings usually consist of a polymeric matrix (binder) with embedded piezoelectric ceramics (second phase or pigment) in the form of microparticles or nanoparticles. Piezoelectric paints have gained prominence in aerospace applications among the various categories of smart coatings, especially for structural health monitoring and absorbing radiation. These coatings (in the form of thin/thick films) are also being applied in the place of brittle piezo-ceramics in various microelectronic devices, for example, in gas sensors and flexible electronics, as well as in various energy-harvesting applications. This review paper focuses on the current state of research for the processing and characterization of piezoelectric composites used as paints/coatings films. Special emphasis is on: (i) the processes of application of piezoelectric paints/coatings in the form of a single layer or stacks of thick films and (ii) the processes of poling these piezoelectric coatings. Various modes and process parameters of poling and their effects on the piezoelectric output of different piezoelectric composites are discussed with examples from the literature. Finally, we have tried to identify the existing issues and address the possible way forward in terms of industrial or academic research within the domain of piezoelectric paint/coating film. [ABSTRACT FROM AUTHOR]

Piezoelectric (PE) materials play an important role in the emerging field of micro and wearable electronics. Achieving high PE response is a key feature for their use in energy harvesting and sensing systems. In this study, highly porous lightweight composite foams composed of PVDF‐TrFE (70/30 and 80/20 mol%) and different BaTiO3 content (5, 10, and 20 wt%) are prepared by thermally induced phase separation method. The PE foams were structurally and thermally examined by using Fourier‐transform infrared spectroscopy, x‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis analyses. All composite foams were characterized by high β‐phase content, while the addition of ceramic particles resulted in higher crystallinity and thermal stability of the investigated foams. Two distinct poling methods were employed due to the different molar compositions of the copolymers. The PE response was measured by the PE strain coefficient (d33) and the output current (Ip). The composite foams based on PVDF‐TrFE 70/30 mol% copolymer, having two well‐separated Curie temperatures for the organic and inorganic phases, can be polarized to achieve the contribution of both components to the PE performance, reaching the highest value of −28.3 pC N−1 and 130 nA at 10 Hz for the composite with 20 wt% BaTiO3. [ABSTRACT FROM AUTHOR]

Thermal stabilities of relaxor-PbTiO3 single crystals are of great importance due to their limited operational temperatures in devices. Herein, to elucidate how poling conditions influence thermal stabilities, we investigated direct current (DC) and alternating current (AC) poled Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-29PT) crystals grown by solid-state crystal growth, which guarantees more compositional uniformity. Our experiments show that the dielectric permittivity of the DC and AC poled crystals are 3560 and 4970, respectively, after annealing at 99.6°C, implying AC-poling prevails in enhancing thermal stabilities of relaxor-PbTiO3 single crystals. The mechanism behind the dissimilar thermal stabilities can be attributed to different domain configurations.

Sol-gel prepared 0.94(Na 0.5 Bi 0.5 TiO 3) -(0.06-x) CaTiO 3 -x (BaTiO 3) samples show a R 3 c phase for both the poled and unpoled materials. The lattice parameters, volume, distortion, and homogeneous strain (δ) increased with the Ba content for both the poled and unpoled cases. The poling increased the volume, c/a ratio, and lattice distortions for all the compositions. The higher Ba incorporation increased the Ti–Ti distance possibly decreasing the lattice's free energy, making it more stable. Poling induces a long-range ordering. The presence of Ba and simultaneously the effect of poling enables the lattice to transit from a more disordered to a more ordered one. Dielectric constant increased with increasing Ba incorporation. The increase in depolarization temperature (T d) with an increase in the Ba indicates the stability of the ferroelectric phase, which is also evident from the increase in the c/a ratio. The thickness electromechanical coupling factor (K t) continuously increases from 20.64% for x = 0–35.29% for x = 0.05 composition due to the increase in the c/a ratio with Ba incorporation. The piezoelectric coefficient increases from 33 for x = 0 to 110 for x = 0.05. [ABSTRACT FROM AUTHOR]

Thermal stabilities of relaxor-PbTiO3 single crystals are of great importance due to their limited operational temperatures in devices. Herein, to elucidate how poling conditions influence thermal stabilities, we investigated direct current (DC) and alternating current (AC) poled Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-29PT) crystals grown by solid-state crystal growth, which guarantees more compositional uniformity. Our experiments show that the dielectric permittivity of the DC and AC poled crystals are 3560 and 4970, respectively, after annealing at 99.6°C, implying AC-poling prevails in enhancing thermal stabilities of relaxor-PbTiO3 single crystals. The mechanism behind the dissimilar thermal stabilities can be attributed to different domain configurations. Alternating-current poling is of useful for not only enhancing piezoelectric and dielectric properties but also improving the thermal stabilities of relaxor-PbTiO3 single crystals. [ABSTRACT FROM AUTHOR]

The (K,Na)NbO 3 -based ceramics are a very promising type of lead-free piezoelectric materials. In spite of the scientific and technological importance, systematical investigations on the dielectric spectra had been rarely performed so far. This paper reports our study results obtained in the (K 0.50 Na 0.50) 1- x Li x NbO 3 ceramics with either x = 0.03 or x = 0.065 (denoted as KNLN-030 and KNLN-065 ceramics, respectively) in the unpoled state and the poled state, respectively. Before poling, the KNLN-030 ceramic shows a dielectric spectrum of strong frequency dependence with a broad peak of dielectric loss around 1 MHz, while the KNLN-065 one has a dielectric spectrum of weak frequency dependence below 60 MHz at room temperature. After poling, piezoelectric resonance peaks appear and are accompanied by a large step-like reduction of dielectric permittivity ε′ in the dielectric spectra of both two ceramics. More interestingly, the KNLN-065 ceramic exhibits an abnormal phenomenon that there is a marked increases in low-frequency ε′ upon poling, whereas the KNLN-030 one shows normally a large decrease of low-frequency ε′. Further, the KNLN-065 ceramic displays the larger low-frequency ε′ in the poled state than in the unpoled state over a considerably wide temperature range. By contrast, such abnormal phenomenon is recognized only in a limited region above the orthorhombic-tetragonal phase transition in the KNLN-030 ceramic. The analysis of domain structure suggests that the observed abnormal dielectric phenomenon possibly arises from the enhancement of domain-wall mobility. [ABSTRACT FROM AUTHOR]

This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo‐catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950 °C for 4 h. BBT is characterized by an X‐ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X‐ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29 eV, which comes in the photon energy range of ultra‐violet radiation. BBT powder is poled by using Corona poling in the presence of 2 kV mm−1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo–piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo–piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species. [ABSTRACT FROM AUTHOR]

In recent years, PVDF(polyvinylidene fluoride) and its copolymers have attracted great attention in the development of energy-harvesting devices because of their unique properties such as good flexibility, environmental friendliness, high halogen and acid resistance, lightweight and good biocompatibility. Compared to the most commonly used PZT (lead zirconate titanate), the piezoelectricity of PVDF and its copolymer-based materials is relatively low. To further expand the applications of PVDF, there is an urgent need for efficient methods to prepare high piezoelectric polymers or composites. In this work, the crystal phases are introduced first. Then, the preparation methods of PVDF and its copolymer-based materials are summarized, which are mainly focused on four determining factors of piezoelectricity. The mechanisms of piezoelectric β-phase formation and α- to β-phase transformation are introduced. The influence parameters of each process and their interactions are discussed in detail. In the last section, the progress of the preparation methods is summarized. This work will provide useful information to researchers working on piezoelectric composites.

Poly(vinylidene fluoride) (PVDF) and its copolymers have been widely studied due to their excellent piezoelectricity and ferroelectricity. In this study, composite films are prepared by adding Ni nanoparticles (0.00–0.3 wt%) into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) matrix by solution casting, uniaxial stretching, and high electric field poling. It is found that when the maximum electric field E max for poling is 130 MV m−1, the calibrated open circuit voltage of the pure PVDF–HFP films reaches 3.12 V, which is much higher than those poled by a lower electric field (70 MV m−1: 1.40 V; 90 MV m−1: 2.29 V). This result shows that the effect of poling on the generated output voltage is decisive. By adding 0.1 wt% Ni nanoparticles, it increases to 3.84 V, 23% higher than that of the pure PVDF–HFP films. To further understand the enhancement mechanism, the effects of Ni nanoparticles on initial crystallization, uniaxial stretching, and high electric field poling are investigated by X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, and differential scanning calorimetry.

Abstract This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo‐catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950 °C for 4 h. BBT is characterized by an X‐ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X‐ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29 eV, which comes in the photon energy range of ultra‐violet radiation. BBT powder is poled by using Corona poling in the presence of 2 kV mm−1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo–piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo–piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species.

Abstract Wearable skin mountable devices, more than flexibility, require conformability, stretchability, and a high water vapor transmission rate, so that the perspiration processes are not blocked, to assure comfort and stability of use in contact with living bodies. Skin mountable stretchable devices with piezoelectric devices have been reported, based on the integration of polyvinylidene fluoride foils with discrete electrodes and stretchable substrates, and show potential in revolutionizing medical devices for remote monitoring applications. However, the electrodes and active layer are usually not stretchable, only the carrier substrate. The study reports the full description of a novel fully printed stretchable piezoelectric device, printed directly over a stretchable polymer foil of thermoplastic polyurethane. The stability of the response of the stretchable piezoelectric devices is used as movement sensors through their output potential. An electronic skin based on a fully printed circuit with a matrix of 15 all‐printed piezoelectric devices is prepared and investigated and used directly mounted on different body parts, and the real‐time monitoring of movements are recorded and analyzed.

The polyvinylidene fluoride trifluoroethylene P(VDF-TrFE) copolymer is polymorphic with two main phases called α (paraelectric) and β (ferroelectric). Effects of annealing, cooling, and poling on the phase transitions are studied in thin films. More precisely, the α-β structural transition is investigated in copolymer capacitors with flexible electrodes and substrate using in situ synchrotron X-ray diffraction. After annealing above the Curie transition, another phase called δ is put in evidence during cooling as α transforms into β. With combined effect of annealing and poling, a sharp phase transition is put in evidence from β to δ at 96 °C after stopping poling (E = 70 MV m−1) and a continuous phase transition occurs from δ to α in the range from 100 to 110 °C. The δ phase has high crystallinity with a domain size (normal to the film surface) of approximately 50 nm i.e. more than three times larger than for β. These phase transformations occur at relatively small electric field because of additional thermal effect and stress change for β and δ/α due to morphological changes. Permittivity and ferroelectric measurements performed on the copolymer capacitors allow confirming the phase transitions from β to δ and finally to α. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) presents highly useful piezo and pyro electric properties but they are predicated upon the processing methods and the ensuing volume fraction of the β-phase. Production of PVDF with higher β-phase content for additive manufacturing (AM) is particularly desirable because it can enable the creation of custom parts with enhanced properties. Necessary steps from compounding to the testing of a 3D printed piezo sensitive sensor are presented in this paper. AM process variables and the influence of zinc oxide (ZnO) nanofiller on crystallinity, viscosity, and electromechanical properties of PVDF, have been explored. Fourier-transform infrared spectroscopy (FTIR) measurements confirm that a high cooling rate (HCR) of 30 °C min−1 promotes the conversion of the α-into the β-phase, reaching a maximum of 80% conversion with 7.5–12.5% ZnO content. These processing conditions increase the elastic modulus up to 40%, while maintaining the ultimate strength, ≈46 MPa. Furthermore, HCR 10% ZnO-PVDF produces four times higher volts per Newton when compared to low cooling rate, 5 °C min−1, pristine PVDF. A piezoelectric biomedical sensor application has been presented using HCR and ZnO nanofiller. This technique also reduces the need for post-poling which can reduce manufacturing time and cost. [ABSTRACT FROM AUTHOR]

The present study is an experimental study dealing with the effect of poling direction on piezoelectric performance. Here, Pb[Zr0.52Ti0.48]O3 (PZT-5A) samples were poled at different angles, and the longitudinal d 33 eff and transverse d 31 eff piezoelectric strain coefficients were measured. In addition, analytical solutions for variation of d 33 eff and d 31 eff with poling orientation were also developed. It was observed that the experimental results were in good agreement with the analytical solution. Although for PZT-5A piezoelectric coefficients decreased with poling orientation, it was theoretically predicted that these piezoelectric coefficients could be enhanced multiple times for other materials. [ABSTRACT FROM AUTHOR]

Relaxor-type lead-perovskite piezoelectric single crystals (SCs) are ABO3-type piezoelectric materials with lead (Pb) at the A site and composite oxides such as magnesium (Mg), zinc (Zn), indium (In), niobium (Nb), and titanium (Ti) at the B site. The development and application of these materials have been pursued in earnest since the 1980s. The piezoelectric constant d33 and electromechanical coupling coefficient k33 of these SCs are much higher than those of conventional PZT ceramics. Currently, eight companies around the world are mass producing and selling these SC transducers, and in particular, more than 1 million units of this SC transducers have already been put into practical use for medical ultrasound probes, and in recent years, the range of its use has been further expanded. In this article, the history, current status, and future progress of lead-perovskite piezoelectric SCs are chronologically introduced, including not only published papers but also patents. In particular, the major topics of the past few years, low-cost solid state crystal growth (SSCG) process, textured ceramics process, and innovative AC poling technology are discussed in detail. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) and its copolymers exhibit excellent piezoelectric properties and are potential materials for high efficiency energy harvesting devices. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films are prepared by the solution casting method. The prepared film is then subjected to mechanical stretching and poling process. By adjusting the temperature of the poling process and the elongation ratio of the mechanical stretching process, the relative content of β-phase F(β) increases significantly, leading to high piezoelectric performance. The maximum output voltage of the PVDF-HFP films poled at 40°C reaches 3.67 V, 71% higher than that of the films poled at room temperature. Fourier transform infrared spectroscopy analysis (FTIR), XRD (X-ray diffraction), and differential scanning calorimetry are used to investigate the influences of mechanical stretching and poling process on the crystal structure to discover the enhancement mechanism. This work provides a straightforward and low-cost route to prepare high piezoelectric PVDF-HFP-based materials.

The photodielectric effects of rare earth elements Er, Eu, and Ho doped Na 1/2 Bi 1/2 TiO 3 (NBT) ceramics are investigated. The dependence of light intensity and irradiation time on the photodielectric effects were clarified, and the thermal-induced and photo-induced changes in permittivity are distinguished. At 1 kHz, the Δε r /ε dark (Δε r = ε photo -ε dark) of NBT-Er/Eu and NBT-Er/Ho are 2.57 % and 2.08 %, respectively. Furthermore, poling and quenching treatments are employed to improve the photodielectric effect of NBT-Er/Ho ceramics. At 1 kHz, the Δε r /ε dark of poled and quenched NBT-Er/Ho increase to 5.22 % and 2.71 %, respectively. The increase of Δε r /ε dark of poled sample is resulted from the lattice distortion of the ceramics while the increase of Δε r /ε dark of quenched sample is due to the increase in oxygen vacancies. This work is conducive to understand the unconventional optical and dielectric effects in ferroelectric ceramics. [ABSTRACT FROM AUTHOR]

[Display omitted] • BaCu x Ti 1-x O 3-x nanofibers were prepared by hydrothermal method. • Poling can improve the tribocatalytic activity of BaCu 0.02 Ti 0.98 O 2.98 nanofibers. • High conductivity is resulted from Cu2+ doping, smaller grain size and poling effect. BaCu x Ti 1-x O 3-x (x = 0, 0.01, 0.02, 0.03, 0.04) nanofibers were synthesized via the hydrothermal method and subsequently subjected to poling. The impact of composition on their tribocatalytic performance and the underlying catalytic mechanism were investigated. After 100 min, all poled BaCu x Ti 1-x O 3-x nanofibers exhibited superior tribocatalytic efficiency compared to pure BaTiO 3 , with BaCu 0.02 Ti 0.98 O 2.98 poled nanofibers achieving a degradation rate of up to 80 % for RhB solution. This is because the increased conductivity and reduced carrier recombination rate which were caused by a 0.02 Cu doping, smaller grain size and poling effect. Control experiments confirmed that both stirring and the presence of a catalyst are essential prerequisites for tribocatalysis. Furthermore, the universality, selectivity, stability, and main active group O 2 – of poled BaCu x Ti 1-x O 3-x (x = 0, 0.01, 0.02, 0.03, 0.04) nanofibers were verified. Lastly, although the tribocatalytic efficiency presented in this paper does not match that of piezoelectric catalysis, the latter requires ultrasonic conditions that are challenging to find naturally. As a result, tribocatalysis offers greater potential for practical applications. [ABSTRACT FROM AUTHOR]

Significantly enhanced photoelectrochemical (PEC) performance of the visible light active photoanodes of ferroelectric Bi 0.5 Na 0.5 TiO 3 nanostructure has been demonstrated by tuning the electrical polarization of the film. The photocurrent density of unpoled Bi 0.5 Na 0.5 TiO 3 photoanode increases from 0.48 mA cm−2 at 1 V with respect to Ag/AgCl to 1.21 mA cm−2 after negative poling, whereas it decreases to 0.18 mA cm−2 after positive poling. The incident photon-to-current conversion efficiency (IPCE) of the nanostructure photoanodes has been observed to vary from 5% to 28% just by changing the direction of electric polarization. The change in the PEC performance and enhancement in the IPCE value after switching the polarization state of Bi 0.5 Na 0.5 TiO 3 photoanodes have been attributed to the modification in the band bending at the interface of semiconductor electrode/electrolyte, leading to facilitate the increment in photogenerated charge transfer efficiency. The modulation in the band bending and variation in the charge transfer method after switching the polarization state are confirmed by Mott-Schottky (M-S) and electrochemical impedance spectroscopy (EIS) measurements. Our work provides a new visible light active ferroelectric nanostructure material for efficient visible light active photoelectrochemical performance. [Display omitted] • Hydrothermal method has been used to synthesize Bi0.5Na0.5TiO3 nanostructures. • PEC activity of Bi0.5Na0.5TiO3 photoanode improved by changing the polarization state. • Negative poled Bi0.5Na0.5TiO3 photoanode shows current density of 1.21 mAcm-2 at 1 V. • Charge transfer process on the application of electric field polarization is proposed. [ABSTRACT FROM AUTHOR]

A new methacrylic monomer, 3,5-bis[2-(N-ethylanilino)ethoxy]benzyl methacrylate (MBA), has been synthesized. Methacrylic copolymers with different content of bi-chromophore fragments in the side chain were obtained by radical copolymerization of methyl methacrylate and MBA, followed by azo-functionalization reaction. The composition of the obtained copolymers was established, and their thermal properties were determined. Thin films of synthesized copolymers were prepared by spin-coating and the nonlinear optical characteristics of the obtained materials were investigated. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries are receiving unprecedented attention owing to their markedly high safety and sustainability, yet their lifespan particularly at high rates is largely limited by the poor reversibility of zinc metal anodes, due to the random ion diffusion and sluggish ion replenishment at the reaction interface. Here, a tunnel‐rich and corona‐poled ferroelectric polymer‐inorganic‐composite thin film coating for Zn metal anodes to tackle above problems, is proposed. It is demonstrated that the poled ferroelectric coating can better deconcentrate and self‐accelerate ion migration at coating/Zn interface during the electroplating process than untreated ferroelectric coating and bare Zn, thus enabling a compact and horizontally‐aligned Zn morphology even at ultrahigh rates. Notably, a maximal cumulative plating capacity of over 6500 mAh cm−2 (at 10 mA cm−2) is achieved for the surface‐modified Zn metal anode, showing extraordinary reversibility of Zn plating/stripping. This work provides new insights in stabilizing Zn metal electrodeposition at the scale of interfacial ion diffusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • NBT-Er\Eu and NBT-Er\Ho exhibit rapid light response and self-bleaching behavior. • The PL intensity increases significantly after poling and quenching treatments. • Multicolor luminescence behavior is also obtained in NBT-Er\Eu ceramics. With the continuous development of the society, optical ceramics are more and more widely used in daily life. In this work, the photochromic (PC) and photoluminescence (PL) properties of Na 1/2 Bi 1/2 TiO 3 (NBT)-based ceramics doped with different rare-earth elements (Er, Eu, and Ho) are investigated. It is found that NBT-Er\Eu and NBT-Er\Ho ceramics have good up-conversion PL properties under 980 nm laser excitation. After poling and quenching treatments, the PL intensity of NBT-Er\Eu ceramics increases by 1.5 and 11.7 times, respectively, and the NBT-Er\Ho ceramics increases by 5.1 and 3.6 times, respectively. Besides, the rare-earth ions doped NBT-based ceramics exhibit fast PC response and self-bleaching behavior. In addition, multicolor luminescence behavior (from bright green to orange-yellow) is obtained in NBT-Er\Eu ceramics, suggesting the potential application of this material in the field of optical information storage and optical anti-counterfeiting. Therefore, this work not only provides a new PC material exhibiting fast PC response and self-bleaching behavior, but also develops new universal strategies to modulate PL properties without changing the composition. [ABSTRACT FROM AUTHOR]

Thermal poling is a widely used method for creating glass surfaces with modified structure and altered properties by application of DC voltage. The mechanism of structural change has remained controversial, especially as poling is performed well below the glass transition temperature. Specifically, the role of Joule heating in facilitating structural transformation has remained an open question, conceivably through local heating to temperatures approaching Tg. Here, we investigate this possibility directly by in situ measurements of the local glass temperature during poling using infrared imaging. Examination near the anode region reveals only a slight temperature increase (~10°C) above the furnace temperature at the start of poling, and remains a few hundred degrees below Tg throughout. SIMS analysis revealed a ~1‐µm thick alkali depletion layer next to the anode. XPS analysis of the anode, cathode, and unpoled regions shows complex changes in structure and composition including migration of alkali ions, injection of hydrogen at the anode interface, removal of non‐bridging oxygen, and polymerization of the network via electrolysis. All these changes arise as a result of high electric field (~106 V/cm) produced across the highly resistive depletion layer, and refutes any significant increase in the temperature by Joule heating as the cause of their creation. [ABSTRACT FROM AUTHOR]

Flexoelectricity is a phenomenon that can yield an electromechanical coupling in all dielectric materials, whereas piezoelectricity presents itself in specially treated (electrically poled) ferroelectric materials. The present study explores the possibility of achieving electrical poling in a material, purely by mechanical means, by virtue of flexoelectricity and thereby harnessing the potential of coexistence of the two phenomena. A theoretical investigation on a functionally graded ferroelectric material sample of square shape with barium titanate and polyvinylidene fluoride as its constituents is conducted in this direction using isogeometric analysis based computational framework. Applied mechanical load on the material results in varying magnitude of electric field inside the material, which in some fraction of the material reaches a magnitude sufficient enough to yield a permanent poling. Simulation results suggest that it is possible to achieve poling of up to 75% of the material volume. This partially poled material is later considered for its contribution in the total electromechanical coupling of the material. The combination of piezoelectric and flexoelectric effects is found to enhance the equivalent piezoelectric coefficient in converse electromechanical (by up to 90%) coupling while a detrimental effect is observed in direct equivalent piezoelectric coefficient (by up to 89%) due to this combination. [ABSTRACT FROM AUTHOR]

The thermal relaxation of second order optical nonlinearity in subsurface layer of a poled soda-lime silicate glass was studied. It is shown that the glass annealing below glass transition temperature leads to full relaxation of the nonlinearity. At the same time, the measurements of thermostimulated depolarization current demonstrate that spatial electric charge formed in the course of the glass polarization relaxes above glass transition temperature. This allows concluding that the second order optical nonlinearity in poled glasses is not induced by the spatial electric charge.

The nonradiative recombination of electrons and holes has been identified as the main cause of energy loss in hybrid organic–inorganic perovskite solar cells (PSCs). Sufficient built‐in field and defect passivation can facilitate effective separation of electron–hole pairs to address the crucial issues. For the first time, we introduce a homochiral molecular ferroelectric into a PSC to enlarge the built‐in electric field of the perovskite film, thereby facilitating effective charge separation and transportation. As a consequence of similarities in ionic structure, the molecular ferroelectric component of the PSC passivates the defects in the active perovskite layers, thereby inducing an approximately eightfold enhancement in photoluminescence intensity and reducing electron trap‐state density. The photovoltaic molecular ferroelectric PSCs achieve a power conversion efficiency as high as 21.78 %. [ABSTRACT FROM AUTHOR]

The design of active optical devices integrating second‐order nonlinear (SONL) optical responses typically relies on the use of dielectric crystalline materials such as lithium niobate (LN) or semiconductors such as GaAs. Despite high SONL susceptibilities, these materials present important geometry constrains inherent to their crystalline nature limiting the complexity of the designed photonic systems. Conversely, amorphous materials are versatile optical media compatible with broad platform designs possessing a wide range of optical properties attributable to their composition flexibility. Demonstrated here for the first time in an amorphous inorganic material, a magnitude of SONL optical susceptibility (χ(2) = 29 pm V−1 at 1.06 µm) comparable to that of LN single crystal is reported. By using a thermo‐electrical imprinting process, fine control of the induced uniaxial anisotropy is demonstrated at the micrometer scale. This work paves the way for the future design of integrated nonlinear photonic circuits based on amorphous inorganic materials enabled by the spatially selective and high SONL optical susceptibility of these promising and novel optical materials. [ABSTRACT FROM AUTHOR]

Using the experimental setup for poling film samples with capability of continuous monitoring of generation signal of second harmonic, the conditions of effective orientation of chromophore molecules based on polyfluoro-substituted triaryl pyrazoline and dicyan-substituted isophoron in micron films of polycarbonate are determined. The second harmonic is excited with the pulse Nd:YAG laser with 1064 nm when chromophore molecules are oriented in the field of corona discharge. The dependences of signal level of the second harmonic on the potential at field mesh and on the potential at needle electrode are measured. [ABSTRACT FROM AUTHOR]

The effect of polymer matrices on the nonlinear-optical properties of composite materials with guest chromophores containing a divinylquinoxaline π-electronic bridge has been investigated. Poly(methyl methacrylate) and different methacrylic copolymers as well as epoxy-amine oligomers with azo chromophores in the backbone or as side groups have been used as polymer matrices. The use of a polymer matrix containing carboxylic groups has resulted in significant decrease in the nonlinear-optical coefficient d33 as compared to the case of poly(methyl methacrylate) matrix with a guest chromophore content of 20 wt%. For materials with binary chromophores, d33 values of the studied materials have been higher than for conventional composites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Increase in c/a ratio, octahedral tilt, and strain with DC electrical poling. • Increase in dielectric permittivity with incorporation of BCZT in NBT lattice. • Improvement in piezoelectric coefficient due to the tensile octahedral strain. • Reduction of the degree of diffuseness with poling. A considerable increase in the c/a ratio, tilt angle, octahedral strain, and Ti-Ti distance with an application of electric field was observed for all the compositions in (1 -x) (Na 0.5 Bi 0.5 TiO 3).x (Ba 0.85 Ca 0.15 Ti 0.90 Zr 0.10 O 3) ceramics. In the x = 0.09 sample, a P 4bm phase (∼45 %) was observed which reduced to ∼ 15 % upon poling. The tilt angle modifies the A 1 phonon mode at 784 cm−1 upon substitution and application of the electric field. Incorporating Ba 0.85 Ca 0.15 Ti 0.90 Zr 0.10 O 3 increased the maximum dielectric permittivity (ε m) from ∼ 2466 (x = 0) to ∼ 3231 (x = 0.09). The degree of diffuseness (γ) also increased with substitution from ∼ 1.384 (x = 0) to ∼ 1.980 (x = 0.09). With poling the value of γ was observed to decrease for each composition. The transformation from a compressive octahedral strain to a tensile one increased the piezoelectric coefficient (d 33). The d 33 value increased from ∼ 70 (x = 0) to ∼ 120 (x = 0.06). [ABSTRACT FROM AUTHOR]

Numerous investigations on the development of the relaxor-PbTiO3 ferroelectric crystals have been carried out since their extraordinary properties were revealed. Recent developments on these crystals have offered further advances in electromechanical applications. In this review, recent developments on relaxor-PbTiO3 crystals and their practical applications are reviewed. The single crystal growth methods are first discussed. Two different strategies, poling and doping, for piezoelectric improvement are surveyed in the following section. After this, the anisotropic features of the single crystals are discussed. Application perspectives arising from the property improvements for electromechanical devices are finally reviewed.

Epoxy nano–micro composite specimen prepared with micro silica and ion trapping nanoparticle, by shear mixing process, was exposed to gamma radiation and its performance for space charge and charge trap characteristics were analysed. The threshold for space charge accumulation of epoxy nanocomposites reduces and rate of space charge accumulation increases with an increase in dosage of gamma irradiation. The average growth of space charge density during poling and charge decay rate during depoling are relatively higher for gamma-irradiated specimens than the virgin specimen. The initial surface potential has a marginal reduction with increase in the dosage of gamma radiation, but the surface potential decay rate has increased significantly. Trap distribution characteristics indicate more number of shallow traps and increase in charge mobility after irradiation. The relative permittivity and loss tangent of the specimens have high impact due to gamma irradiation. The activation energy calculated from DC conductivity by Arrhenius law reduces with increment in radiation dose. Laser-induced breakdown spectroscopy reflected no change in elemental composition with gamma-irradiated specimen. The variation in plasma temperature and ion line to atomic line intensity ratio with dosage of gamma radiation have direct correlation to the Vickers hardness number of the specimens.

Untargeted nuclear magnetic resonance (NMR) metabolomics was employed, for the first time to our knowledge, to characterize the metabolome of human osteoblast (HOb) cells and extracts in the presence of non‐poled or negatively poled poly‐L‐lactic acid (PLLA). The metabolic response of these cells to this polymer, extensively used in bone regeneration strategies, may potentially translate into useful markers indicative of in vivo biomaterial performance. We present preliminary results of multivariate and univariate analysis of NMR spectra, which have shown the complementarity of lysed cells and extracts in terms of information on cell metabolome, and unveil that, irrespective of poling state, PLLA‐grown cells seem to experience enhanced oxidative stress and activated energy metabolism, at the cost of storage lipids and glucose. Possible changes in protein and nucleic acid metabolisms were also suggested, as well as enhanced membrane biosynthesis. Therefore, the presence of PLLA seems to trigger cell catabolism and anti‐oxidative protective mechanisms in HOb cells, while directing them towards cellular growth. This was not sufficient, however, to lead to a visible cell proliferation enhancement in the presence of PLLA, although a qualitative tendency for negatively poled PLLA to be more effective in sustaining cell growth than non‐poled PLLA was suggested. These preliminary results indicate the potential of NMR metabolomics in enlightening cell metabolism in response to biomaterials and their properties, justifying further studies of the fine effects of poled PLLA on these and other cells of significance in tissue regeneration strategies. [ABSTRACT FROM AUTHOR]

A simple technique to fabricate microchannels in glasses with self-assembled silver nanoparticles (NPs) in the channels is presented. It combines thermal-electric poling of silver-to-sodium ion-exchanged glass slides with a patterned anodic electrode, formation of the microchannels via selective etching off the unpoled slide regions, and hydrogen annealing. The annealing results in the growth of NPs only on the bottom of the channels. The studies performed allowed optimizing the channels' depth and NPs surface density for Surface Enhanced Raman Scattering (SERS) based sensing and microfluidic applications. We have demonstrated that the formed NPs allow detection of 1/20 of BPE (1,2-Di(4-pyridyl)ethylene 97%) monolayer, the evaluated Raman enhancement factor being ~4·107. The proposed approach based on the glass poling allowed us the fabrication of ~1 μm deep channels and easy multiplication of the structures because the anodic electrodes used for the poling are capable of multiple usage. Image 1 • Chemical etching of a thermally poled glass allows formation of microchannels. • Diffusion of reduced silver from the glass forms nanoparticles in the channels. • The self-assembled nanoparticles in the channels enhance Raman signal up to 4·107. [ABSTRACT FROM AUTHOR]