Enhancement Of Piezoelectric Properties Research Articles

Enhancement of piezoelectric properties of CaBi2Nb2O9 ceramics by Ce doping and direct reaction sintering

CaBi2Nb2O9 (CBN) with the Aurivillius phase has a high Curie temperature (TC) and remarkable fatigue resistance, which has great potential for application as high-temperature sensors. However, due to its low piezoelectric properties, its practical application remains a great challenge. In this paper, Ca1-xCexBi2Nb2O9 ceramics were prepared by the direct reaction sintering (DRS) and conventional preparation (CP) methods, respectively. The experimental results indicate that Ce doping can increase the piezoelectric coefficient d33 of CBN ceramics by about two times. Among them, the grain size of the samples prepared by the DRS method is finer and more uniform, and the d33 value of DRS samples is about 3.6–9.4 % higher than that of CP samples. The DRS sample Ca0·97Ce0·03Bi2Nb2O9 has a d33 value of 18.9 pC/N, a TC of 948 °C, and a resistivity of 1.1 × 105 Ω cm at 600 °C. This study shows that DRS method is an effective densification method, which can prepare CBN-based ceramics with excellent comprehensive properties, and provides an innovative preparation route to explore CBN-based ceramics with excellent piezoelectric properties.

Enhancing the piezoelectric performance of composite PVDF flexible films through optimizing β phase content, investigating additive effects, step‐wise polarization, and thermal pressing time for energy harvesting applications

AbstractPolyvinylidene fluoride (PVDF), known for its piezoelectric versatility, emerges as a key contender for advancing efficient and sustainable energy harvesting in nanogenerators. This study explores the potential enhancement of piezoelectric properties in flexible PVDF polymers, employing a comprehensive approach through the solution casting method. The investigation integrates diverse additives, thermal treatments, and polarization methods to optimize performance, focusing on the impact of the β phase transition on electrical voltage generation. Utilizing the Taguchi experimental design, the study identifies optimal conditions for the composite PVDF film (OPT‐PVDF) through FT‐IR, XRD, and DSC analyses, with output voltage measurements confirming superior performance compared to pure PVDF (P‐PVDF). Specifically, BN‐doped PVDF films, with an 80% β phase content, achieve an impressive 6.48 V output voltage. This research underscores PVDF's potential for energy harvesting, emphasizing the pivotal role of optimizing β phase content, additive strategies, and the effects of polarization and thermal treatments. The study further evaluates the effect and necessity of subsequent thermal treatment and step‐wise polarization effects on the composite PVDF film material. The findings indicate that BN‐doped composite PVDF films, produced under optimal conditions, exhibit advanced piezoelectric properties.

Effects of heterovalent ions doping-induced oxygen octahedral distortion and defect chemical change on piezoelectric characteristics and thermal stability of PHT-PIN ceramics

Electromechanical devices require functional materials possessing excellent piezoelectric properties, good thermal stability, and high electromechanical coupling coefficients. To modulate the piezoelectric, dielectric, and electromechanical characteristics of 0.89Pb(Hf0.47Ti0.53)O3-0.11Pb(In1/2Nb1/2)O3 (PHT-PIN) piezoelectric ceramics, heterovalent ions of lithium (Li) and tungsten (W) were doped through a traditional solid-phase reaction approach. On the one hand, large lattice distortions caused by the doped W6+ resulted in the shortening of BO bonds while an increase in the local displacement of B-site ions. Moreover, a mismatch occurred for the oxygen octahedral dimensions, and a subsequent disruption of the long-ranged ordered ferroelectric domains was observed, which resulted in the formation of microdomains. On the other hand, the changes in the concentration of oxygen vacancy defects induced by the Li and W doping inside the ceramic were comprehensively analyzed. The decrease in the concentration of oxygen vacancies was found to be accompanied by the enhancement of piezoelectric properties of the material. Excellent comprehensive performance (piezoelectric coefficient d33 = 655 pC N−1, Curie temperature Tc = 321.1 °C, dielectric constantεr = 3352.31, electromechanical coupling coefficient kp = 0.67, and residual polarization strength Pr = 55 μC cm−2) was obtained for 0.2 mol % doping amount of Li+ and W6+ ions. This work, therefore, proposes a novel strategy for the origin of piezoelectric properties and inspires doping of other heterovalent ions to improve the piezoelectric properties of ceramics. It further promotes the development of Pb-based piezoelectric ceramics for electromechanical devices that can efficiently operate under high-temperature environments.

Varied domain structures in 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals

Single crystals of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-30PT) with a composition close to the morphotropic phase boundary have demonstrated remarkable electromechanical properties, stimulating intensive research interest in the field of piezoelectrics. Domain structures have long been associated with their overall piezoelectric properties, thereby garnering particular research interest for the enhancement of piezoelectric properties. Here, we report on three distinct domain structures in this material. Through a combination of X-ray diffraction reciprocal space mapping and piezoresponse force microscopy measurements, an M A crystal structure has been confirmed. The three-dimensional polar vectors of the three domain structures have been reconstructed with two 4M A and one 2M A domain structures. Correlations between different domain structures and their local electrical switching properties have been revealed. Our study of the PMN-30PT single crystal examines diverse domain structures at the mesoscale in detail, which provides valuable insight into the relationship between structures and properties of the material.

Sound insulation enhancement of PVB/PVDF film by adding LiCl

Polyvinyl Butyral (PVB) has been widely used in laminated glass depending on its excellent adhesion, impact resistance, and transmittance. However, it will provide a quieter environment if its sound insulation characteristics can be improved, especially in the mid to low frequency range. In this paper, PVB/PVDF composite film was prepared by electrostatic spinning and hot pressing. By adding 0.1 % LiCl, the β-phase content and the output voltage of PVDF were increased 15 % and 47 %, respectively. The average transmission loss of PVB/PVDF film has been enhanced for 4.4 dB at 64–1600 Hz. It is attributed to the enhancement of piezoelectric properties of PVDF films by adding LiCl. Moreover, the transmittance and impact resistance of the laminated glass based on PVB/PVDF/LiCl have been confirmed by UV–vis and falling ball impact test.

The effect of Cu doping on the piezoelectric properties of ZnO systems: First-principles calculations

First-principles calculations are performed, revealing a significant enhancement of the piezoelectric properties of wurtzite Zn[Formula: see text]O[Formula: see text] upon the incorporation of a single Cu atom. Research has demonstrated that the piezoelectric constant [Formula: see text] reaches its maximum value at a doping concentration of 1.4% for Cu atoms. The lattice parameters a and c of Zn[Formula: see text]O[Formula: see text] are decreased and the piezoelectric strain coefficient [Formula: see text] is increased by replacing one Cu atom in Zn[Formula: see text]O[Formula: see text]. It is found that elastic softening is the primary factor responsible for the increase of [Formula: see text] in Zn[Formula: see text]Cu1O[Formula: see text]. By differential charge density analysis, it is found that the covalency between Cu–O bonds is lower than that of Zn–O bonds, and the covalent bonding characteristics are weakened. Bader charge analysis shows that the charge of Cu is higher than that of Zn, indicating a more significant ionic bonding feature than that of Zn. Thus, a weaker covalent and stronger ionic bond are considered to play an essential role in promoting elastic softening for ZnO, which eventually promotes a significant enhancement in piezoelectric properties.

Insight into the Ultrahigh Electric Performance of Aurivillius CBTa-CBN Solid Solution.

For bismuth layered structural ferroelectrics (BLSFs), CaBi2Ta2O9 (CBTa) demonstrates valuable application potential for a high Curie temperature (TC) of 923 °C and a good high-temperature resistivity, but low piezoelectric constant d33 values. Compared with CBTa-based ceramics, CaBi2Nb2O9 (CBN) with a high TC of 940 °C is easy to modify and realize excellent enhancement of piezoelectric properties. Here, by introducing a CBN-based component into CBTa, a new type of solid-solution ceramic with the formula Ca0.94(LiCe)0.03Bi2Ta2O9-xCa0.94(LiCe)0.03Bi2Nb2O9 (LC-CBTa-xCBN) is fabricated to obtain the advantages of both of them. Moreover, optimal electrical performances are obtained in the LC-CBTa-0.4CBN ceramic (d33 ∼ 14.1 pC/N, ρ ∼ 1.08 × 106 at 600 °C, TC ∼ 940 °C). The correlated characterizations, including structure and electricity, provide further realization of an enhanced performance mechanism. Therefore, this method of constructing a new type of solid solution provides a new strategy to modify BLSFs.

Enhancement of piezoelectric properties of BF–BT ceramics by using ZrO2 powder bed during the sintering process

AbstractZrO2 powders of various particle sizes (0.15, 0.7, 500 µm) were used to simulate loose powder bed sintering to prepare BF–BT piezoelectric ceramics. The phase structure, dielectric properties, ferroelectric properties, and piezoelectric properties were compared with the samples sintered by the conventional powder bed method (i.e., powder of the same composition as the sample). Results showed that the use of loose ZrO2 powder bed could improve the heat conduction rate and the sintering quality of bulk BF–BT piezoelectric ceramics. The XPS results showed that the samples sintered with 500 µm ZrO2 powder beds had the lowest concentration of Fe2+, exhibited the largest piezoelectric coefficients (d33 = 201 pC/N). In contrast, the sample sintered with a conventional powder bed under the same sintering conditions had a piezoelectric coefficient d33 of 156 pC/N.

Enhanced Piezoelectric Properties in a Single-Phase Region of Sm-Modified Lead-Free (Ba,Ca)(Zr,Ti)O3 Ceramics.

In ferroelectric materials, phase boundaries such as the morphotropic phase boundary (MPB) and polymorphic phase boundary (PPB) have been widely utilized to enhance the piezoelectric properties. However, for a single-ferroelectric-phase system, there are few effective paradigms to achieve the enhancement of piezoelectric properties. Herein, we report an unexpected finding that largely enhanced piezoelectric properties occur in a single-tetragonal-ferroelectric-phase region in the Sm-modified (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT-xSm) system. An electrostrain maximum (0.13%) appears in the single-phase region of the BZCT-0.5Sm composition with the maximum polarization (Pm = 18.37 µC/cm2) and piezoelectric coefficient (d33 = 396 pC/N) and the minimum coercive field (EC = 3.30 kV/cm) at room temperature. Such an enhanced piezoelectric effect is due to the synergistic effect of large lattice distortion and domain miniaturization on the basis of the transmission electron microscope (TEM) observation and X-ray diffraction (XRD) Rietveld refinement. Our work may provide new insights into the design of high-performance ferroelectrics in the single-phase region.

Enhancement of Piezoelectric Properties of Flexible Nanofibrous Membranes by Hierarchical Structures and Nanoparticles.

Piezoelectric nanogenerators (PENGs) show superiority in self-powered energy converters and wearable electronics. However, the low power output and ineffective transformation of mechanical energy into electric energy l limit the role of PENGs in energy conversion and storage devices, especially in fiber-based wearable electronics. Here, a PAN-PVDF/ZnO PENG with a hierarchical structure was designed through electrospinning and a hydrothermal reaction. Compared with other polymer nanofibers, the PAN-PVDF/ZnO nanocomposites not only showed two distinctive diameter distributions of uniform nanofibers, but also the complete coverage and embedment of ZnO nanorods, which brought about major improvements in both mechanical and piezoelectric properties. Additionally, a simple but effective method to integrate the inorganic nanoparticles into different polymers and regulate the hierarchical structure by altering the types of polymers, concentrations of spinning solutions, and growth conditions of nanoparticles is presented. Further, the designed P-PVDF/ZnO PENG was demonstrated as an energy generator to successfully power nine commercial LEDs. Thus, this approach reveals the critical role of hierarchical structures and processing technology in the development of high-performance piezoelectric nanomaterials.

Development of New Bio-Composite of PEO/Silk Fibroin Blends Loaded with Piezoelectric Material.

New bio-composite nanofibers composed of polyethylene oxide (PEO)/silk fibroin (SF)/barium titanate (BaTiO3) are introduced in this study. The SF solution was added to the PEO solution to form a PEO/SF blend with different weight percentages (5, 10, 15, 20 wt.%). The PEO/15 wt.% SF blend was selected to continue the experimental plan based on the optimum nanofiber morphology. Different wt.% of BaTiO3 particles (0.2, 0.4, 0.8, 1 wt.%) were added to the PEO/15 wt.% SF blend solution, and the suspensions obtained were introduced to an electrospinning device. The fabricated tissue was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The zeta potential of the solution and the piezoelectric performance of the fabricated tissue were characterized. A newly designed pizoTester was used to investigate piezoelectric properties. The results showed that a well-organized, smooth PEO/15 wt.% SF/0.2 wt.% BaTiO3 nanofiber composite with low bead contents was obtained. Improved properties and electrical coupling were achieved in the newly introduced material. Electrospun PEO/15 wt.% SF/0.2 wt.% BaTiO3 mats increased the output voltage (1150 mV) compared to pristine PEO and PEO/SF composite fibers (410 and 290 mV, respectively) upon applying 20 N force at 5 Hz frequency. The observed enhancement in piezoelectric properties suggests that the prepared composite could be a promising material in cardiac tissue engineering (CTE).

Sb2O3‐modified lead zirconate titanate piezoelectric ceramics with enhancing piezoelectricity and low loss

AbstractLead zirconate titanate (PZT)–based piezoelectric ceramics as important functional materials are widely used in many electromechanical devices. The piezoelectric coefficient and mechanical quality factor are vital property parameters for piezoelectric applications. However, the piezoelectric coefficient is inversely proportional to the mechanical quality factor, resulting in a strong limitation among wide applications. Herein, piezoelectric ceramics composed of (xSb2O3, 0.3‐wt% MnCO3)‐doped (Pb0.92Sr0.08)(Zr0.533Ti0.443Nb0.024)O3 ((xSb, Mn)‐PSZTN) were prepared by a conventional solid‐state process. The excellent piezoelectric properties d33 = 554 pC/N, kp = 0.645, and high mechanical quality factor Qm = 540 were simultaneously obtained at x = 0.1 ceramic in the morphotropic phase boundary region. The enhancement of piezoelectric properties was mainly due to the contribution of irreversible domain wall motion. In particular, the regulation of different defect chemical reactions on the properties showed that Sb2O3 could play the role of both donor and acceptor dopant. This work demonstrated that (0.1Sb, Mn)‐PSZTN ceramic was a good candidate material for high‐power piezoelectric devices.

Polarization Rotation Control Domain Dynamic Response Modulates Piezoelectric Properties of Lead‐Free Thin Films

AbstractDomain orientation engineering regulates the polarization direction of thin film and facilitates the enhancement of piezoelectric properties. A change in polarization direction implies a structural change in the piezoelectric thin film. In this work, some unexpected results are obtained by preparing three orientations of Bi0.5Na0.5TiO3‐based lead‐free piezoelectric thin films to amplify this structural change. In distinction to the conventional perception, the piezoelectric properties decrease with increasing polarization direction. This anomaly is influenced by the concentration of structural defects, and rotation of the polarization direction may induce a change in the electronic structure of the material and hence in the concentration of structural defects. Ultimately, the suppression of the domain dynamics response by increasing structural defects leads to the worst piezoelectric properties for thin films with the traditionally perceived optimal (100) orientation. The revelation of this anomaly has implications for the design of the next generation of high‐performance piezoelectric thin films.

Lead-Free BiFeO3-Based Piezoelectrics: A Review of Controversial Issues and Current Research State.

Lead-free electroceramics represent an emerging area of research that has the potential to enable new green advances in electronics. Research has mainly focused on the development of new piezoelectric materials for replacing lead containing oxides exhibiting superior electromechanical behavior. Lead-free BiFeO3-based materials are not only the promising candidates to replace lead-based materials but also show intriguing properties which may inspire innovative material design for the next generation of lead-free piezoceramics. This review aims to highlight the current state of research and overlooked aspects in lead-free BiFeO3-based ceramics, which could be insightful in elucidating certain controversial issues. Current strategies to reduce high conductivity, influence of chemical heterogeneity on both functional properties and crystal structure, effective heat treatment procedures, and the role of pseudo-cubic structures on the enhancement of piezoelectric properties are subjects of highlighted within this review as they have a significant impact on the quality of BiFeO3-based lead-free piezoelectrics (but are often disregarded).

Enhanced electrical properties and thermal stability of W/Cr co‐doped BIT-based high‐temperature piezoelectric ceramics

Bi 4 Ti 3 O 12 (BIT), a typical layered-structure ferroelectric with a high Curie temperature ( T C ), is a promising material for high-temperature sensors. Herein, W/Cr co-substitution at the B-site of BIT ceramics (BITWC100 x ) is carried out to investigate the phase structure, domain structure, and electrical properties. The W/Cr addition apparently reduces the concentration of oxygen vacancies, effectively improving the ferroelectric and piezoelectric properties as well as the resistivity of the BIT ceramics. The BITWC2 ceramic exhibits a high piezoelectric coefficient ( d 33 = 31.1 pC/N), a moderate T C (651 °C), a large remnant polarization ( P r = 12.2 μC cm −1 ), and a prominent direct current resistivity (5.49 ×10 6 Ω·cm at 500 °C). Moreover, the BITWC2 ceramic possesses a large d 33 of 26.6 pC/N at an annealing temperature of 600 °C, indicating the excellent thermal stability of the piezoelectric coefficient. Overall, the BITWC100 x ceramics can be used in piezoelectric devices at temperatures up to 500 °C. • BITWC100 x ceramics with a high T C and excellent electricity properties can be used in high-temperature piezoelectric devices. • The information of domain structure is obtained by PFM. • The refinement of the domain size contributes to enhancement of piezoelectric properties of BITWC100 x ceramics.

Monoclinic domain populations and enhancement of piezoelectric properties in a PZT single crystal at the morphotropic phase boundary

The origin of the strong piezoelectric phenomenon in $\mathrm{Pb}{\mathrm{Zr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{\mathrm{O}}_{3}$ (PZT) perovskites still suffers from a lack of complete understanding. It concerns the distinction between the intrinsic and extrinsic mechanisms that govern PZT's piezo activity. These two mechanisms have been investigated in single crystal $\mathrm{Pb}{\mathrm{Zr}}_{0.54}{\mathrm{Ti}}_{0.46}{\mathrm{O}}_{3}$ at the morphotropic phase boundary. After poling in a DC electric field, the piezoelectric properties were examined on the same crystal by observing piezoelectric resonances to determine the piezoelectric coefficient ${d}_{31}$ and measuring quasistatic deformation to determine the coefficient ${d}_{33}$. The domain populations were investigated during and after poling in a DC electric field. These populations were also investigated as a function of DC fields for strengths similar to those used to measure quasistatic piezoelectric properties for a poled crystal. The experiments indicate that the intrinsic origin of the enhancement of the piezoelectric properties is connected with a change in the population of domains with monoclinic symmetry, in which there is an easy polarization rotation under the action of the electric field.

Performance enhancement of Pb(In1/2Nb1/2)O3-PbTiO3 ferroelectric single crystals using pulse poling

The regular domain structure is beneficial to the enhancement of piezoelectric properties of relaxor-PbTiO3 ferroelectric crystals after alternating current poling (ACP). However, one shortcoming of ACP is that there are some non-rotational domains. Another is that ACP has no effect on polar axis-oriented crystals. Therefore, ACP is not very satisfactory for the morphotropic phase boundary (MPB) composition. Here, we demonstrate a pulse poling (PP) method that can lead to substantially increase the piezoelectric coefficient d33 of MPB region Pb(In1/2Nb1/2)O3-PbTiO3 (PIN-PT) single crystals. The d33 and free dielectric permittivity εT33/ε0 of ACP [001]c-oriented 0.65PIN-0.35PT single crystals are 1490 pC/N and 3360, which are smaller than DCP sample (1640 pC/N and 3620). The d33 and εT33/ε0 after PP method are 2400 pC/N and 5390, having 61% and 60% improvement compared with ACP method. This work presents a new domain engineering method for achieving high piezoelectricity of these MPB region ferroelectric crystals.

Enhancement of Piezoelectric Properties in Low-Temperature Sintering PZN–PZT Ceramics by Sr2+ Substitution

Enhancement of Piezoelectric Properties in Low-Temperature Sintering PZN–PZT Ceramics by Sr2+ Substitution

Epitaxy Enhancement of Piezoelectric Properties in P(VDF‐TrFE) Copolymer Films and Applications in Sensing and Energy Harvesting

AbstractWith the rapid development of wearable and flexible electronics, energy harvesting from the environment has attracted much attention. As one representative piezoelectric polymer, poly(vinylidene fluoride‐trifluoroethylene) [P(VDF‐TrFE)] is an expected candidate for mechanical energy harvesting and self‐powered mechanical sensors due to its flexibility and moderate piezoelectricity. However, low crystallinity and electroactivity limit its electric performance. Controllable modulation of microstructure and crystallization is one feasible measure to enhance piezoelectric property. Here the piezoelectric properties of epitaxial P(VDF‐TrFE) films which are fabricated via removable polytetrafluoroethylene template method are reported. Piezoelectric measurement between 50 and 800 Hz presents an averaged d33 coefficient of −40.7 pC N−1 for epitaxial film, ≈61% enhancement to that of non‐epitaxial one. Transverse piezoelectric experiment indicated that epitaxy process enhanced open‐circuit voltage and short‐circuit current outputs. Simple piezoelectric energy harvesters are prepared by depositing both epitaxial and nonepitaxial films on flexible polyimide substrates. Epitaxial film shows a maximum generated power density of 0.118 µW cm−2 and energy conversion efficiency of 0.81%, both of which are much larger than those from nonepitaxial film (0.047 µW cm−2 and 0.30%). Piezoelectric films are used to monitor bending, punching, twisting and finger tapping operations, where epitaxial film exhibited larger open‐circuit voltage responses than nonepitaxial one.

Comparative Solution Synthesis of Mn Doped (Na,K)NbO3 Thin Films.

(K0.5 Na0.5 )NbO3 (KNN) is a promising lead-free alternative for ferroelectric thin films such as Pb(Zr,Ti)O3 . One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non-stoichiometry. This paper compares three acetate-based chemical solution synthesis and deposition methods for 0.5 mol % Mn-doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10-8 A cm-2 up to electric fields as high as 600 kV cm-1 , which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two-step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed.