Piezoelectric Voltage Coefficient Research Articles

Impact of ionizing radiation on structural, dielectric, and piezoelectric properties of Sr modified PZT

Ion irradiation effects on piezoceramic (Pb0.94 Sr0.04) (Zr0.52 Ti0.48)O3 (PSZT) are investigated by using 4 MeV carbon (C), 9 MeV copper (Cu), and 20 MeV gold (Au) ions. The energies of incident ions are selected in order to target the same range of all incident ions in the material, while producing different amounts of vacancies. The ion irradiation is performed with fluences of 1×1013, 1×1014, and 1×1015 ions/cm2 using Tandem Pelletron accelerator (5UDH-2). Post irradiation changes in PSZT are investigated via various structural, dielectric, and piezoelectric measurement techniques. Results divulge that the irradiation process disturbs the crystallinity along with reduction in X-ray diffraction (XRD) peak intensities owing to strain induced structural defects. A small decrease in dielectric constant is observed due to trapped charges, which screen the depolarization after irradiation. However, a significant decrease is detected in piezoelectric charge coefficients (d33) and piezoelectric voltage coefficients (g33) due to switching of micro domains of PSZT as a result of energy observed during irradiation process. These results indicate that ion irradiation has damaging effects on the properties of PSZT. The discussed information may be utilized to assess performance of PSZT based devices under radiation rich environments such as space.

Ferroelectric domain formation and photocatalytic activity on porous alkali niobate piezoelectric ceramics

Present study showed synthesis of novel type of porous alkali niobate piezoelectric ceramics, and the formation of domains and photocatalytic activity for the porous piezoelectric ceramics were investigated while comparing with dense ceramics to confirm enhancement of domain orientation and photocatalytic activity around pores. Porous Li0.06Na0.47K0.47NbO3 piezoelectric ceramics were synthesized by a template method using polymethylmethacrylate as a pore former agent. Uniform pores with 6 µm in diameter were dispersed in the porous ceramics. Porous ceramics synthesized with 10 vol % of the pore former agent showed piezoelectric voltage coefficient, 29 mVm/N, which is same as that of the dense ceramics. Smaller striped domains formed at an edge of pores on the porous ceramics, indicating that orientation of domains was promoted by electric field concentration around the pores. Through photoreduction reaction of Ag+ ion, local precipitation of Ag was shown around the pores on the poled porous ceramics, whereas Ag was located over an entire surface of unpoled porous ceramics. Highest photocatalytic activity was shown for the poled porous ceramics in photodecomposition test of methylene blue. These results clearly indicated photocatalytic activity was enhanced on ferroelectric domains around pores of porous piezoelectric ceramics.

Enhanced dielectric and piezoelectric properties in potassium sodium niobate/polyvinylidene fluoride composites using nano-silicon carbide as an additive

Piezoelectric materials are an indispensable part of modern life. Yet the existing environmental issues with conventional lead-based piezoelectrics has motivated scientist to develop novel substitutes including lead-free piezoelectric polymer composites. Following this path, the present research has focused on the fabrication of ternary composites of Polyvinylidene fluoride (PVDF)/Potassium Sodium Niobate (KNN)/nano-Silicon carbide (SiC) via hot compression molding and studying the effect of additives on the PVDF structure and the electrical properties of the composite. The obtained scanning electron micrographs and density measurements showed that the fabrication method provided dense samples. The activated polarization phenomena in the prepared samples enhanced dielectric permittivity and dielectric loss at a constant frequency with increasing KNN and SiC contents. Besides the expected dipole polarization, the presence of interfaces in the composites gave rise to the Maxwell–Wagner–Sillars effect and its corresponding polarization phenomenon. The semiconductive nature of SiC also promoted space charge polarization. However, these properties were frequency-dependent because the first two polarization mechanisms are deactivated at high frequencies. XRD patterns showed that SiC addition can alter the primary crystalline structure of PVDF and promote β-phase formation in the poled samples. Piezoelectric measurements confirmed the significant role of SiC addition to PVDF-KNN composites. The most significant increase in the piezoelectric properties was observed in PVDF-60KNN-1SiC, with a 183% increase in d33 value. The PVDF-80KNN-1SiC had the highest d33 value of 30.5 pC/N. It also had the best piezoelectric voltage coefficient and hence the highest figure of merit. Higher SiC contents restrict the efficiency of poling by forming a conductive path across the sample which would deteriorate the piezoelectric performance of the material. The present findings show that PVDF-KNN-SiC composites can be considered as a potential flexible piezoelectric material for future applications.

A Systematic Review of Piezoelectric Materials and Energy Harvesters for Industrial Applications.

In the last three decades, smart materials have become popular. The piezoelectric materials have shown key characteristics for engineering applications, such as in sensors and actuators for industrial use. Because of their excellent mechanical-to-electrical and vice versa energy conversion properties, piezoelectric materials with high piezoelectric charge and voltage coefficient have been tested in renewable energy applications. The fundamental component of the energy harvester is the piezoelectric material, which, when subjected to mechanical vibrations or applied stress, induces the displaced ions in the material and results in a net electric charge due to the dipole moment of the unit cell. This phenomenon builds an electric potential across the material. In this review article, a detailed study focused on the piezoelectric energy harvesters (PEH’s) is reported. In addition, the fundamental idea about piezoelectric materials, along with their modeling for various applications, are detailed systematically. Then a summary of previous studies based on PEH’s other applications is listed, considering the technical aspects and methodologies. A discussion has been provided as a critical review of current challenges in this field. As a result, this review can provide a guideline for the scholars who want to use PEH’s for their research.

Superior transverse piezoelectricity in organic-inorganic hybrid perovskite nanorods for mechanical energy harvesting

Developing highly piezoelectric nanoparticles (NPs) with inherent mechanical-electrical coupling effect is critically important for energy harvesters, self-powered sensors and actuators. Over the past decades, the NPs with a high longitudinal piezoelectric coefficient (d 33 ) were developed for piezoelectric nanogenerators (PENGs) that operate under periodic vertical compression mode. As an alternative, high-performance PENGs can be developed by taking advantage of materials with a superior transverse piezoelectric coefficient (d 31 ). In this work, we successfully synthesized an organic-inorganic hybrid perovskite (OIHP) nanorods (NRs) of (4-aminotetrahydropyran) 2 PbBr 2 Cl 2 [(ATHP) 2 PbBr 2 Cl 2 ] that exhibits a large d 31 of 64.2 pC/N, which is 3 times higher than the well-known poly (vinylidene fluoride) (PVDF) polymer (21 pC/N). A saturated polarization of 5.4 μC/cm 2 and a piezoelectric voltage coefficient (g 33 ) of 900 mV•m/N are also reported. The (ATHP) 2 PbBr 2 Cl 2 NRs can be dispersed homogeneously in a polymer matrix to make piezoelectric composite films. Due to their excellent flexibility, uniform dispersion and large surface area the concurrent vertical strain and lateral bending yield a high piezoelectric performance. We fabricate a unique piezoelectric composite film for PENGs, which can produce an output voltage (V oc ) of 90 V and a short-circuit current (I sc ) of 6.5 μA under an applied force of only 4.2 N, outperforming a number of the state-of-the-art PENGs ( Table S2 ). The harvested electrical energy is stored in a capacitor by a two-stage energy transfer mechanism for self-powered electronics. This is the first work, that not only reveals the large transverse piezoelectricity in the (ATHP) 2 PbBr 2 Cl 2 NRs, but also coins a route to employ it in practical energy harvesting devices. • Synthesis of (ATHP) 2 PbBr 2 Cl 2 hybrid perovskite nanorods (NRs) for mechanical energy harvesting applications. • The nanorods exhibit a transverse piezoelectric coefficient (d 31 ) of 64.2 pC/N, 3-times higher than the PVDF film. • The (ATHP) 2 PbBr 2 Cl 2 @PDMS film generates an output voltage of 90 V and a current of ~ 6.5 μA with an applied force of 4.2 N. • The PENGs can charge a 1 μF capacitor to 5.5 V in 20 s and promising to be integrated with the electronic circuits.

Multiscale Heterogeneity Strategy in Piezoceramics for Enhanced Energy Harvesting Performances.

Piezoelectric energy harvesters (PEHs) with piezoceramics as the core can convert low-frequency vibration energy that is ubiquitous in the environment into electrical energy and are at the frontier of research in the field of energy. The high piezoelectric charge coefficient (d) together with the large piezoelectric voltage coefficient (g) are essential for enhancing the energy harvesting performances of PEHs working on a nonresonant state. However, conventional doping and solid solution design strategies lead to the same increase or decrease trend of d and dielectric permittivity ε, making it difficult to obtain a high g value because g = d/ε. Herein, exceptionally well-balanced performances of high d and large g are achieved simultaneously in modified Pb(Zr, Ti)O3(PZT)-based ceramics via a multiscale heterogeneity strategy, which involves coordination among the defect dipole, hierarchical domain, and composite. The electromechanical parameters of the optimal specimen are not only superior to those of many state-of-the-art commercial counterparts but also exhibit good thermal stability. Most importantly, the assembled PEH with the optimal specimen shows excellent variable temperature power generation characteristics. This work provides a paradigm for building PEH material through a multiscale heterogeneity strategy, expected to benefit a wide range of electromechanical coupling materials.

Improvement of Figure of Merit Pb(Zr,Ti)O₃-Pb(Zn,Ni,Nb)O₃-Pb(In,Nb)O₃ Piezoelectric Ceramics.

Figure of merit the product of piezoelectric charge constant and the piezoelectric voltage constant-d33 × g33 in piezoelectric energy harvesting systems are critical measures in energy harvester applications. It is difficult to achieve high figure of merit because of the interdependence of d33 and the relative dielectric constant, εr. Until now, the prohibitive amount of effort required to solve this problem has led to it being considered an unsolvable issue. Lead zirconate titanate ceramic, Pb(Zr,Ti)O₃, has been reported to exhibit high values of d33 and εr. However, to be employed as piezoelectric energy harvester, a candidate material is required to exhibit both high piezoelectric charge coefficient and high piezoelectric electric voltage coefficient simultaneously. To enhance the figure of merit of Pb(Zr,Ti)O₃-based materials, dopants have also been considered. Pb(Zn,Ni,Nb)O₃- added Pb(Zr,Ti)O₃, Pb(Zr,Ti)O₃-Pb(Zn,Ni,Nb)O₃ ceramic has been reported to exhibit a high d33 value of 561 pC/N. It's dielectric constant has also been reported to be low at 1898. In this study, Pb(Zr,Ti)O₃-Pb(Zn,Ni,Nb)O₃-Pb(In,Nb)O₃ was investigated in the context of enhancing the figure of merit of Pb(Zr,Ti)O₃-based materials. During the proposed process, we increased the corresponding figure of merit by adding Pb(In,Nb)O₃ material. Besides exhibiting a low dielectric constant, the Pb(In,Nb)O₃ material was also observed to exhibit high d33 × g33 as the proposed doping increased the value of d33 greatly, while maintaining the dielectric constant (Yan, J., et al., 2019. Large engancement of trans coefficient in PZT-PZN energy harvesting system through introducing low εrPIN relaxor. Journal of the European Ceramic Society, 39, pp.2666-2672). Further, we conducted an optimization experiment by controlling the doping concentration and the sintering temperature.

Estimating the true piezoelectric properties of BiFeO3 from measurements on BiFeO3-PVDF terpolymer composites

• BiFeO 3 particles were embedded in non-conducting non-piezoactive PVDF terpolymer. • Dielectric and piezoelectric properties of BiFeO 3 -PVDF composite with different volume fraction were studied. • The piezoelectric charge and voltage coefficients of granular BiFeO 3 were determined by using Yamada and Poon model. BiFeO 3 is an interesting multiferroic material with potential use in sensors and transducers. However, the high coercive field and low dielectric strength of this material make the poling process extremely difficult. Poling becomes a lot easier if the ceramic particles are incorporated in a non-conductive polymer with comparable dielectric properties. In this work, unstructured composites consisting of BiFeO 3 particles in a non-piezoactive PVDF terpolymer matrix are made with a ceramic volume fraction ranging from 20% to 60%. The highest piezoelectric charge and voltage constant values (d 33 = 31 pC/N and g 33 = 47 mV m/N) are obtained for a BiFeO 3 -PVDF terpolymer composite with a volume fraction of 60%. The Poon model is chosen to analyse the volume fraction dependence of the dielectric constant while the modified Yamada model is used to analyse the piezoelectric charge constant data. It is concluded that the maximum possible piezoelectric constant for bulk BiFeO 3 can be as high as 56 pC/N.

Freeze casting of lamellar-structured porous lead-free (Na0.52K0.48)(Nb0.95Sb0.05)O3 piezoceramic with remarkable enhancement in piezoelectric voltage constant and hydrostatic figure of merit

The study reports the development of lamellar-structured, porous lead-free (Na0.52K0.48)(Nb0.95Sb0.05)O3 ceramics, abbreviated as NKNS, using the freeze-casting method with water as pore-forming agent. The effect of directional porosity on the microstructure, dielectric, and piezoelectric properties of the lead-free porous material is investigated. Furthermore, the effects of conventional and microwave sintering on microstructure and piezoelectric properties have also been analyzed. In addition, the study compares conventional and corona poling too. The results depicted no deterioration of piezoelectric properties (d33:130 pC/N), despite being ~ 50% porosity, along with reasonably good hydrostatic piezoelectric strain coefficient (dh: 60pC/N). The samples exhibited hydrostatic piezoelectric voltage coefficient (gh) of 58.70 mV.m/N providing a significant value of the hydrostatic figure of merit (HFOM = dh∙gh: 3522 × 10–15 Pa−1) for the porous NKNS ceramic which is nearly 39 times more than the dense ceramic. Considering its unique advantages such as environmental friendly, less dense, wide performance range with enhanced figure of merit, the lamellar-structured NKNS ceramic is a promising material for sensor and transducer applications.

Mechanical, dielectric, ferroelectric and piezoelectric properties of 0–3 connectivity lead-free piezoelectric ceramic 0.94Bi0.5Na0.5TiO3–0.06BaTiO3/Portland cement composites

In this research, lead-free piezoelectric ceramic 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 (BNT–BT)/Portland cement (PC) composites have been fabricated for use as sensor in structural health monitoring applications. BNT–BT ceramic particles were mixed with Portland cement using ceramic particles content of 30–60 vol.% to form 0–3 connectivity pattern BNT–BT/PC composite. The acoustic impedance, compressive strength, dielectric, ferroelectric and piezoelectric properties of the composites were investigated as a function of ceramic content. The results indicated that the BNT–BT ceramic content of ≈ 40–60 vol.% are the optimal BNT–BT ceramic contents for acoustic impedance matching between composite and concrete structure. The compressive strength was found in the region of 28.19–35.30 MPa for BNT–BT/PC composites is close to that of normal concrete. The dielectric constant (er) value of composites increased as BNT–BT ceramic content increased, while the dielectric loss value reduced with higher BNT–BT ceramic content. The BNT–BT ceramic content in these composites has a beneficial effect on the ferroelectric behavior. Moreover, composite with BNT–BT ceramic content of 60 vol.% exhibited the highest piezoelectric coefficient ( $${d}_{33}$$ ) value of 42 pC/N. The piezoelectric voltage coefficient ( $${g}_{33}$$ ) of BNT–BT/PC composites was found to be in the range of 13.96 mV m/N to 17.00 mV m/N. Furthermore, the er and $${d}_{33}$$ values of composites were close to the cubes model. According to the results, it is noted that these composites have good compatibility with concrete structure and has the potential for use as sensor in structural health monitoring applications.

Large thickness-mode electromechanical coupling and good temperature stability of 1–3 PZT/epoxy composites

Piezoelectric composites with 1–3 connectivity have attracted great attentions recently in ultrasonic transducers such as biomedical imaging and industrial flaw detection. However, data related to piezoelectric temperature stability of the composites can be rarely found in the literature. Thus, it is vital to study the piezoelectric temperature stability for practical applications. We chose a commercially available excellent PZT-51 ceramic to prepare a 1–3 PZT/epoxy piezoelectric composite with an improved dice-fill method and examined both its room-temperature piezoelectric performances and electromechanical temperature stability in this study. This composite shows the well-balanced overall performance with high thickness-mode electromechanical coupling coefficient kt of 0.73, large piezoelectric voltage coefficient g33 of 65 × 10−3 Vm/N, and moderate acoustic impedance Z of 13.8 Mrayl. Most importantly, kt is very stable with nearly no temperature dependence in the common usage temperature range from − 30 to 100 °C. This work indicates that selecting a proper PZT ceramic is an essential precondition for obtaining the excellent piezoelectric composites.

A large piezoelectric voltage coefficient in aluminate-sodalite-type improper ferroelectric oxides

An excellent piezoelectric response has been demonstrated in the aluminate-sodalite-type oxides (Ca1−xSrx)8[AlO2]12{MoO4}2, around the MPB-like vertical phase boundary, shedding light on the development of eco-friendly piezoceramics with excellent functionalities.

Achieving Ultrahigh Piezoelectricity in Organic–Inorganic Vacancy-Ordered Halide Double Perovskites for Mechanical Energy Harvesting

Piezoelectric charge coefficient (d33) and piezoelectric voltage coefficient (g33) are the two most critical parameters that define output performance of piezoelectric nanogenerators (PNGs). Herein, we propose a vacancy-ordered double perovskite of TMCM2SnCl6 (where TMCM is trimethylchloromethylammonium) with a large d33 of 137 pC/N and g33 of 980 × 10–3 V·m/N. The piezoelectric coefficients are considered from the halogen-bonding-mediated synergistic movements of atomic displacement in inorganic [SnCl6]2– octahedrons, as well as the molecular rotation of organic TMCM+, which is revealed by a combined density functional theory (DFT) and experimental study. The TMCM2SnCl6 possesses a high saturated polarization (Ps) of 8.7 μC/cm2, a high Curie temperature (Tc) of 365 K, and a low coercive field (Ec) of 0.6 kV/cm. The output voltage (Voc) and current (Isc) of the PNGs are 81 V and 2 μA at an applied mechanical excitation of (4.9 N, 40 Hz). We hope this work will provide guidance in energy harvesting by innovatively designing highly piezoelectric perovskites for the PNGs.

Comparative study of the Bi(Ni0.5Zr0.5)O3-PbTiO3 and Bi(Mg0.5Zr0.5)O3-PbTiO3 piezoelectric materials for energy harvesters

ABSTRACT In this study, piezoelectric properties of 0.4Bi(Ni0.5Zr0.5)O3–0.6PbTiO3 (BNZ-PT) and 0.4Bi(Mg0.5Zr0.5)O3–0.6PbTiO3 (BMZ-PT) ceramics were investigated and compared with those of Pb(Zr,Ti)O3 in energy harvester applications. Their piezoelectric properties are comparable with those of Pb(Zr,Ti)O3 based materials, although they have lower lead contents. By optimizing the sintering temperature, the piezoelectric charge coefficients (d33) were improved to 438 and 351 pC/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively, whereas the piezoelectric voltage coefficients (g33) were improved to 25.02 × 10−3∙V∙m/N and 28.37 × 10−3∙V∙m/N for 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The generated energies were estimated by measuring the generated output voltages. Generated energy densities of 1.67 and 1.01 mJ/cm3 were obtained from 0.4BNZ-0.6PT and 0.4BMZ-0.6PT, respectively. The optimum sintering conditions were found by observing the changes in the piezoelectric constant, dielectric constant, and density as a function of the sintering temperature.

Novel 1–3 (K,Na)NbO3-based ceramic/epoxy composites with large thickness-mode electromechanical coupling coefficient and good temperature stability

The 1–3 piezoelectric composites are an important type of artificial functional materials for ultrasonic transducers. Currently, there are increasingly strong demands to replace the lead-containing materials. Excellent 1–3 0.96(K0.48Na0.52) (Nb0.96Sb0.04)O3−0.03BaZrO3−0.01(Bi0.50Na0.50)ZrO3 ceramic/epoxy (abbreviated hereafter as KNNS-0.03BZ-0.01BNZ/epoxy) piezoelectric composites were prepared by a modified dice-and-fill technique. Compared to the monolithic KNNS-0.03BZ-0.01BNZ ceramic, the developed composites possess much larger electromechanical coupling coefficient kt of 0.54–0.67 and piezoelectric voltage coefficient g33 of 64–91 × 10−3 Vm/N. In addition, these composites also possess other favorable properties such as low values of acoustic impedance Z of 6.9–13.4 Mrayl, dielectric coefficient ε33 of 130–400 and mechanical quality factor Qm of 1.3–4. More importantly, kt is weakly temperature-dependence in the common usage temperature range between −30 °C and 100 °C. The result indicates that the 1–3 KNNS-0.03BZ-0.01BNZ/epoxy piezoelectric composites have a great potential for high-frequency ultrasonic transducers.

Soft and Hard Piezoelectric Ceramics for Vibration Energy Harvesting

The question as to which piezoelectric composition is favorable for energy harvesting has been addressed in the past few years. However, discussion on this topic continues. In this work, an answer is provided through a feasible method which can be used in selecting piezoelectric material. The energy harvesting behavior of hard (P4 and P8) and soft (P5 and P5H) lead zirconate titanate (PZT) ceramics was investigated. The results show that the maximum piezoelectric voltage coefficient g33 and transduction coefficient d33 × g33 were obtained in P5 ceramic. Meanwhile, the power generation characteristics at low frequencies were compared by the vibration energy harvester with a cantilever beam structure. The results indicate that the energy harvester fabricated by the P5 ceramic with the maximum d33 × g33 values also demonstrated the best power generation characteristics. The results unambiguously demonstrate that the power density and energy conversion efficiency of the energy harvesting devices are dominated by the d33 × g33 value of the piezoelectric materials.

Good piezoelectricity of self-polarized thick epitaxial (K,Na)NbO3 films grown below the Curie temperature (240 °C) using a hydrothermal method

Using a hydrothermal method, (K0.88Na0.12)NbO3 films were deposited at 240 °C on (100) cSrRuO3//(100)SrTiO3 substrates. Moreover, without any poling treatment, direct and inverse transverse piezoelectric coefficients, e31,f, near 0 kV/cm were approximately −5.0 C/m2 for the as-deposited film. This value was nearly unchanged following the application of an electric field and poling treatment, suggesting that as-deposited films are almost in a fully self-polarized state without the application of an electric field. As-deposited films with a thickness of up to 22 μm showed constant piezoelectricity without any poling treatment. The films did not crack or peel because of substrates due to the small thermal strain originating from the low deposition temperature. The figures of merit (FOM) for the vibration energy harvester [FOM = e31,f2/(ε0εr)] and sensor [FOM = e31,f/(ε0εr)] were estimated to be good at 32.8 GPa and –5.9 GV/m, respectively, primarily because of the low relative dielectric constant of ∼110. Furthermore, the piezoelectric voltage coefficient g31 [= d31/(ε0εr)] was estimated and demonstrated a high value of 0.073 Vm/N.

Gel Synthesis of Hexaferrites Pb1-xLaxFe12-xZnxO19 and Properties of Multiferroic Composite Ceramics PZT-Pb1-xLaxFe12-xZnxO19.

We investigated the opportunities for obtaining hexaferrites Pb1−xLaxFe12−xZnxO19 (x = 0–1) from citrate–glycerin gel and showed that synthesis occurs via the formation of the Fe3O4 phase; products with a small amount of hematite impurity Fe2O3 can be obtained after firing at 800 to 900 °C with 0 ≤ x ≤ 0.5. If x > 0.5, perovskite-like LaFeO3 is formed in samples, so that if x = 0.9–1, the synthesis products virtually do not contain phases with hexaferrite structures and represent a mixture of LaFeO3, Fe2O3, and Fe3O4. Within the range of 0 ≤ x ≤ 0.5, the electrical and magnetic characteristics of hexaferrites Pb1−xLaxFe12−xZnxO19 are slightly dependent on x and have the following average values: A relative permittivity ε/ε0 ~ 45, a dielectric loss tangent tan δ ~ 0.6, an electrical resistivity R ~ 109 Ohm cm, coercivity Hc ~ 3 kOe, saturation magnetization Ms ~ 50 emu/g, and remanent magnetization Mr ~ 25 emu/g. The magnetoelectric (ME) ceramics 50 wt.% PZTNB-1 + 50 wt.% Pb1−xLaxFe12−xZnxO19 (PZTNB-1 is an industrial piezoelectric material based on lead titanate zirconate (PZT) do not contain impurity phases and have the following characteristics: Piezoelectric coefficients d33 = 10–60 and −d31 = 2–30 pC/N, piezoelectric voltage coefficients g33 = 2–13 and −g31 = 1–5 mV m/N, an electromechanical coupling coefficient Kp = 0.03–0.13, magnetic parameters Hc = 3–1 kOe, Ms = 50–30, and Mr = 25–12 emu/g. The maximum ME coupling coefficient ΔE/ΔH ~ 1.75 mV/(cm Oe) was achieved with x = 0.5.

Electromechanical behaviors of soft and hard PZTs under different compressive stress pulses

In the present study, soft and hard PZTs discharge experiments under extrusion/impact were carried out to analyze the electromechanical behaviors under open and short circuit conditions. The results show that when subjected to extrusion, the soft PZT is more sensitive to stress, the hard PZT has higher discharge capacity under high-impedance (regard as open-circuit) condition, and the force-electric relationship of the two PZTs satisfy the traditional piezoelectric equation. Under impact, the open-circuit elastic compliance coefficient of two PZTs increases with the increase of stress, the maximum value is about 50 times of the quasi-static value, and the piezoelectric voltage coefficient is about 20% of the quasi-static value. The short-circuit elastic compliance coefficient of soft PZT is 10 times of the quasi-static coefficient, and the dynamic piezoelectric strain coefficient is 250% of the quasi-static coefficient. However, the dynamic stress-strain of hard PZT is nonlinear and the dynamic piezoelectric strain coefficient is 500 × 10−12 m/V, which is about double of the quasi-static constant.

Top-seeded solution growth and investigation of electrical and energy storage performance of pure and doped (1−x)Na0.5Bi0.5TiO3–xBaTiO3 ferroelectric single crystals

Urgent requirement exists to develop the lead-free piezoelectric energy storage devices, sensors and actuators for the reduction of toxicity in the environment. This paper deals with the lead-free ferroelectric single crystals with excellent piezoelectric behaviour. A series of pure and doped (Mn and Nb) (1−x)Na0.5Bi0.5TiO3–xBaTiO3 (NBBT) bulk size single crystals was successfully grown by the top-seeded solution growth (TSSG) method. The crystal growth, phase confirmation, compositional analysis, electric properties and energy storage density were investigated. The NBBT crystal belongs to perovskite structure and is confirmed using X-ray Powder diffraction pattern (PXRD). The elemental composition of the NBBT crystals grown by TSSG was investigated by the Inductively coupled plasma-Atomic Emission spectroscopy (ICP-AES). The electrical properties like dielectric constant (er = 674, 700, 837, 694, 2872 and 378) and dielectric loss (tanδ = 0.2, 0.6, 0.5, 0.7, 0.47 and 0.27) were measured and it was found to be relaxor-type behaviour due to diffuseness of NBBT crystals by the dielectric permittivity. The piezoelectric coefficients (d33 = 374, 290, 167, 110, 410 and 103) and piezoelectric voltage coefficients (g33 = 6.26, 4.6, 2.2, 1.79, 1.6 and 3.0) were obtained. Greater value of remnant polarization (Pr = 87, 46, 30, 0.30, 117 and 0.11), maximum polarization (Pm = 104, 55, 49, 1.08, 136 and 0.34) and lower value of coercive electric field (Ec = 16.5, 13.8, 26, 0.64, 20 and 233) were obtained from the P–E hysteresis loop of NBBT crystals studied to identify good performance of the compositions. The NBBT 90/10 crystal was found to be of 94/06 composition as obtained from ICP-AES. Moreover, NBBT 90/10 was doped by Mn and Nb and its electrical properties were measured. The Mn-doped NBBT 90/10 crystal attained a large energy storage density (W) of 0.27 Jcm−3 at ~ 20 kV cm−1 compared to the undoped and Nb-doped NBBT 90/10 crystal.