Piezoelectric Constant D33 Value Research Articles

The effect of Li/Ce co‐doping on structural and electrical properties of Sr2−x(Li, Ce)x/2Nb2O7 piezoelectric ceramics

AbstractAs a typical perovskite‐like layered structure (PLS) ceramic, Sr2Nb2O7 (SNO) possesses a high Curie temperature TC value above 1300°C, which is expected to work in higher temperature environment. However, pure SNO presents a piezoelectric constant d33 value of ∼ 1 pC/N. Hence, (Li, Ce) ions are doped in SNO ceramics, which increases the distortion of oxygen octahedrons and enhances the intrinsic contribution of piezoelectric properties. The increased domain size with large proportion of high response areas means that the extrinsic contribution is also improved. The introduction of (Li, Ce) ions can also promote ceramic's grain growth and reduce oxygen vacancies, leading to the improvement of electrical properties. The optimal component Sr1.96(Li, Ce)0.02Nb2O7 ceramics exhibit a d33 value of 3.1 pC/N, a higher resistivity of 1.65×106 Ω·cm at 700°C and an excellent thermal stability (a d33 value of 3.0 pC/N after annealing at 1200°C for 2 h). This work provides an effective approach with simple process and low cost for the application of PLS materials in high‐temperature environments.

Potassium Sodium Niobate-Based Lead-Free High-Frequency Ultrasonic Transducers for Multifunctional Acoustic Tweezers

Ultrasonic transducers may need to operate in direct contact with the human body, especially with the skin or closer to blood vessels. Eco-friendly lead-free materials and devices are therefore being vigorously developed for biosafety considerations. This work presents high-performance potassium sodium niobate [(K,Na)NbO3, KNN]-based lead-free ceramics with composition-driven multiphase coexistence and their application on high-frequency ultrasonic transducers for multifunctional acoustic tweezers. A high piezoelectric constant d33 value of 332 pC/N, a good Curie temperature TC value of 348 °C, and improved in situ temperature stability were obtained in the piezoceramics via the construction multiple phases near room temperature and domain engineering. One to three piezocomposites were further fabricated based on the synthesized ceramics for higher electromechanical coupling properties. Lead-free high-frequency transducers as multifunctional acoustic tweezers for precise and selective manipulation of microparticles were designed and manufactured with a high center frequency of 23.4 MHz and a broad -6 dB bandwidth of 75.4%. Additionally, a stable transducer performance was obtained over a test temperature range of 23-60 °C, indicating good thermal stability in environments with fluctuating temperatures. Research on lead-free high-frequency transducers for ultrasound imaging and precise and selective manipulation of microparticles demonstrates their broad potential in fields such as medical therapy and diagnosis.

Enhanced Piezoresponse and Dielectric Properties for Ba1-XSrXTiO3 Composition Ultrathin Films by the High-Throughput Method

The stacked single-unit cell Ba1-xSrxTiO3 (BSTO) thin film designed by the high-throughput method is fabricated by layer-by-layer deposition by laser molecular beam epitaxy, and its ferroelectric and dielectric characteristics as a function of Sr concentration are comprehensively investigated. The permittivity of BSTO exhibits a monotonous increase by Sr with a plateau in the region of 14% < Sr < 85%. Meanwhile, at the low Sr doping regime, the piezoelectric response has been discovered, and the maximum piezoresponse and d33 can reach approximately 139.05 pm and 88 pm/V once an appropriate Ba/Sr ratio is formed, exhibiting a coexistence of a dielectric property and giant piezoresponse. This effective piezoelectric constant d33 value is significantly larger than the conventional chemical doping scenarios, suggesting that the intra-plane interaction is crucial for designing future promising dielectric and ferroelectric thin films via high-throughput technologies.

Multifunctional performance and ferroelectric phase characteristic of BCTH-Eu ceramics prepared by low-temperature sintering via LiBO2 doping

Multifunctional performance [(Ba0.85Ca0.15)0.995Eu0.005](Ti0.9Hf0.1)O3 (BCTH-Eu) ceramics were prepared by conventional solid-state low-temperature sintering method via LiBO2 doping, in which the sintering aid LiBO2 was introduced into the calcined perovskite precursor powder through liquid phase coating technique. Phase-pure perovskite structure BCTH-Eu ceramics are obtained by the method, and the sintering temperature is decreased about 150 °C as compared with the conventional method whose sintering temperature is normally above 1450 °C. The ceramics present rather high density, uniform distribution of grains and elementals, and have submicron meter grain size. Due to complex substitution of cations at A-site and B-site of the perovskite structure, the LiBO2-doped BCTH-Eu ceramics exhibit displacive driven normal ferroelectrics accompanied by apparent diffused relaxation characteristic. The 1340 °C sintered LiBO2-doped BCTH-Eu ceramics present maximum piezoelectric constant d33 value of 314 pC/N poled under 20 kV cm−1, and the ceramics sintered between 1320 °C–1330 °C exhibit excellent comprehensive electrical properties and multifunctional performance. Such excellent multifunctional properties obtained in this work can be partially attributed to the coexistence of multi-ferroelectric phases, which is confirmed by dielectric response fitting and Raman Gaussian fitting.

Dielectric, ferroelectric, and piezoelectric properties of Gd-modified CaBi2Nb2O9 high Curie temperature ceramics

This paper reports the enhanced piezoelectric properties of gadolinium-modified Ca1−xGdxBi2Nb2O9 (CBN-100xGd, where x = 0–0.07) high Curie temperature polycrystalline ferroelectric ceramics. The crystal structure, microstructural morphology, and electrical properties of Gd-modified CBN ceramics are investigated in detail. The results reveal that the Gd-modified CBN ceramics have a pure two-layer Aurivillius-type structure, and exhibit plate-like grains. The resultant Gd-modified CBN ceramics exhibit better piezoelectric and electromechanical properties by comparison with unmodified CBN. The composition of CBN-3Gd exhibits the optimized piezoelectric performance with a high piezoelectric constant d33 value of 13 pC/N and a high Curie temperature Tc of 947 °C. The dc electrical resistivity is significantly enhanced, and that of the CBN-3Gd is 2.45 × 107 Ω cm at 500 °C and 1.53 × 106 Ω cm at 600 °C, which is larger by two orders of magnitude compared with that of unmodified CBN ceramics at the same temperature. Such good electrical properties suggest that the Gd-modified CBN ceramics are promising materials for high-temperature piezoelectric sensor applications.

The effects of Ca, Zr and Sn substitutions into a ternary system of BaTiO3–BaSnO3–BaZrO3 towards its dielectric and piezoelectric properties: a review

The discovery of the dopant effects on BaTiO3 has attracted great interest after a compound of 50(BaTi0.8Zr0.2O3)–50(Ba0.7Ca0.3TiO3) system exhibited extraordinarily high piezoelectric properties (d33 > 600 pC/N). Recently, modifications made on the BaTiO3-based piezoelectric materials, particularly at the A-site, have gained the most attention due to the existence of the morphotropic phase boundary (MPB) region. In this paper, we reviewed several dopants that have been extensively used to enhance the piezoelectric and dielectric properties of a BaTiO3 such as Sn and Zr. A ternary triangle of BaTiO3–BaSnO3–BaZrO3 is used to evaluate the correlations between the changes in the Sn- and/or Zr-doped BaTiO3 piezoelectric ceramic properties. The structural changes that have been affected by the dopant contents were also comprehensively reviewed. There is clear evidence that the dopants significantly affect the intrinsic properties of the BaTiO3-based ceramic materials. The dielectric constant er value increases from 1900 to ~ 6000 at room temperature, while the piezoelectric constant d33 value is also increased from 191 pC/N to ~ 600 pC/N. All the compositions described in this review were prepared by using a conventional solid-state route.

Preparation and characterization of Zn-modified CaBi4Ti4O15 piezoelectric ceramics with lower sintering temperature

The Ca0.85(LiCe)0.075Bi4Ti4−xZnxO15 ceramics are prepared via solid‐state reaction method with lower sintering temperature. The influence of lower sintering temperatures (Ts) on structural and electrical properties is investigated. The repressed volatilization of Bi3+ reduces the impurity phase proportion and oxygen vacancies content in ceramics, which might lead to increased TC value (~ 800 °C), piezoelectric constant d33 value (20 pC/N), high resistivity (6.32 × 105 Ω·cm at 600 °C), and good thermal stability up to 600 °C. Therefore, the Zn-modified ceramics are perceived to be one of promising candidates for high-temperature piezoelectric devices.

Effects of Ba(Zr0.25Ti0.75)O3 substituent on ferroelectric properties in the BiFeO3-PbTiO3 high temperature ceramics

(0.75-x)BiFeO3-0.25PbTiO3-xBa(Zr0.25Ti0.75)O3 (BF-PT-BZT) ternary solid solutions were prepared by the solid state reaction method. It was found from X-ray diffraction analysis that the morphotropic phase boundary (MPB) between tetragonal(T) and rhombohedral(R) phases occurred at the composition range of x from 0.13 to 0.28. For BF-PT-base ceramics, the addition of BZT can effectively decreased the tetragonality (c/a) and improved the ferroelectric as well as piezoelectric properties. The maximum value of piezoelectric constant d33 and electromechanical coupling factor kp were 182 pC/N and 0.34, respectively. Also, the ferroelectric transition temperature (Tc) of BF-PT-BZT ceramics varied in the range of 550–298 °C. It is believed that the BF-PT-BZT ternary solid solutions could be a good candidate for high-temperature applications.

High-performance piezoelectric (K,Na,Li)(Nb,Ta,Sb)O3 single crystals by oxygen annealing

Ferroelectric single crystals exhibit the largest known piezoelectric constants and therefore show high potential for application in electronic devices, including sensors, actuators, and transducers. Their large properties, however, can only be fully exploited if the behavior is not influenced by lattice defects, formed during high-temperature processing. Such defects can inhibit domain-wall movement, increase leakage currents, and are predominantly responsible for the poor performance of the emerging ferroelectric crystals. Here, an approach to considerably enhance the piezoelectric and ferroelectric properties of (K,Na,Li)(Nb,Ta,Sb)O3 crystals by oxygen annealing is investigated. As compared to the non-annealed crystals, polarization, strain, and piezoelectric constant of the annealed sample were enhanced by a factor of two, resulting in an outstanding room-temperature value of piezoelectric constant d33 = 732 pC/N and a peak value of d33 = 1431 pm/V at the orthorhombic-tetragonal transition. The behavior was analyzed using electromechanical measurements, Mössbauer spectroscopy, and impedance spectroscopy, revealing decreased concentrations of both oxygen vacancies and Sb3+ ions after annealing. The findings indicate that the control of the defect chemistry enables these ferroelectric (K,Na)NbO3-based single crystals to outperform their polycrystalline counterparts and reach the values of lead-containing compositions. Moreover, the present strategy enables further detailed studies of the inherent crystal anisotropy and the possibilities for domain engineering.

New piezoelectric composites based on isotactic polypropylene filled with silicate

Polymeric cellular composites are very important materials in modern electronics because they can be used as piezopolymers due to low specific weight, good thermal resistance and high value of piezoelectric constant d33. The aim of this work was to obtain and characterize the cellular polypropylene (PP) composites as materials designed for microelectronics. PP has been modified by addition of commercial silicate filler and the obtained materials were extruded. Then, the composites were subjected to electric field for polarization. Effect of the filler content on the structure and physicochemical properties of the composites have been investigated. The following experimental methods have been applied: SEM, XRD, thermogravimetry, tensile tests and measurements of voltage and electric charge accumulated in the polymer. The piezoelectric constant and stability of piezoelectric properties were also determined. It was found that the growth in the filler content in the polymer causes the increase in the film porosity and the degree of PP crystallinity that reaches 70% for the PP sample with 10% of the filler. Young’s modulus increased also in the presence of the filler. Moreover, the thermal stability of the composites was improved compared to neat PP. The piezoelectric constant of the composites was about 200 pC/N).

Bismuth layer-structured piezoelectric ceramics with high piezoelectric constant and high temperature stability

Bismuth layer structured lead free piezoelectric ceramics in the system Sr1−x Ca x Na0.5Bi4.5Ti5O18 + 1 wt% CeO2 (SC x NBTC; x = 0, 0.25, 0.5, 0.75 and 1) have been prepared through the conventional solid-state reaction method. X-ray diffraction measurement indicates that a single phase layered perovskite was obtained for all compositions, and with the increase of x, the lattice parameter of c/a value have been increased first and then decreased, giving maximum values of c/a = 12.7085 when x = 0.5. At x = 0.25, the SC x NBTC ceramics exhibited the best properties with a large piezoelectric constant d 33 of 31 pC/N and a high Curie temperature of 607 °C. Moreover, SC x NBTC ceramics have outstanding temperature stability and piezoelectric. The SC0.25NBTC ceramics showed high piezoelectric constant d 33 value (31 pC/N) and good stability with no change of d 33 values after annealing at 350 °C. The results indicate that these compounds are very promising piezoelectric materials for high-temperature transducer applications at 350 °C.

Temperature dependent poling behaviour of MnO2 doped Pb[(Mn1/3,Sb2/3)0·03(Zn1/3,Nb2/3)0·15(Zr1/2,Ti1/2)0·82]O3 ceramics

The temperature dependent poling behaviour of MnO2 doped Pb[(Mn1/3,Sb2/3)0·03(Zn1/3,Nb2/3)0·15(Zr1/2,Ti1/2)0·82]O3 lead contain ceramics is investigated in this research. The piezoelectric constant d33 value of the samples poled under 200°C can get to 358 pC N−1. While the d33 value of the samples poled under room temperature is only 102 pC N−1. The piezoelectric constant d33 value and strain level increase more than two times when samples are poled under 200°C. The internal bias field appears quite modest relative to the strain improvement. The origin of the internal bias field is discussed and a mathematical model is proposed to interpret the mechanism.

Effects of MnO2 and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics

Ba0.85Ca0.15Ti0.90Zr0.10O3 + xmol% MnO2 lead-free ceramics have been prepared by a conventional sintering method and the effects of MnO2 and sintering temperature on microstructure, ferroelectric, and piezoelectric properties of Ba0.85Ca0.15Ti0.90Zr0.10O3 lead-free ceramics have been studied. The addition of 0.25 mol% MnO2 promotes grain growth, improves the ferroelectricity of the ceramics and strengthens ferroelectric tetragonal–ferroelectric orthorhombic phase transition near 40 °C. Because of the coexistence of tetragonal and orthorhombic phases and the combinatory effects of soft and hard doping of Mn ions, the ceramic with x = 0.25 exhibits the optimum piezoelectric properties (d33 = 306 pC/N and kp = 42.2 %, respectively). Excess MnO2 inhibits the grain growth and degrades the ferroelectric and piezoelectric properties of the ceramics. Sintering temperature has an important influence on the microstructure, tetragonal–orthorhombic phase transition near 40 °C, ferroelectric and piezoelectric properties of the ceramics. The increase in sintering temperature leads to large grains and more noticeable tetragonal–orthorhombic phase transition near 40 °C, enhances ferroelectricity and thus improves effectively the piezoelectricity of the ceramics. The Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramic sintered at 1350 °C possesses the optimum piezoelectric constant d33 value of 373 pC/N.

Direct Write Assembly of Three-dimensional PZT Woodpile Structure

A novel kind of water based lead zirconate titanate (PZT) ink was developed. Woodpile structures with diameter of micrometer scale were constructed from this ink by using direct write assembly technique. According to the rheological test, the ink shows shear-thinning behavior. Micro-morphology and density test results show that the sintered samples have formed ceramics with high relative density. Measurement of X-ray diffraction (XRD) shows that the main phase of sintered samples is rhombohedral PbZr0.58Ti0.42O3. The value of piezoelectric constant d33 is meas- ured to be 410 pC/N, which shows that the sintered samples exhibit good piezoelectric property. The direct write as- sembly technique has merits of good designability, rapid forming capability and high precision prototyping, which provide new ideas and methods for the design and application of piezoelectric materials and devices.

High temperature lead-free relaxor ferroelectric: Intergrowth Aurivillius phase BaBi2Nb2O9–Bi4Ti3O12 ceramics

Intergrowth BaBi2Nb2O9–Bi4Ti3O12 (BaBi6Ti3Nb2O21) Aurivillius phase ceramic has been found to be a relaxor ferroelectric (RFE) with the highest reported temperature of the maximum of the dielectric permittivity (Tm) of all of the known RFE systems. Dielectric characterization revealed that it has two dielectric anomalies. The first one is a frequency independent broad dielectric constant peak at ∼280 °C, while the second anomaly shows relaxor behavior at 636 °C (100 kHz). There is obvious frequency dispersion of dielectric response at room temperature, which is in agreement with dielectric properties of a typical relaxor. Ferroelectric hysteresis loops and a measurable value of piezoelectric constant d33 confirmed the ferroelectric nature of BaBi6Ti3Nb2O21 ceramics. The piezoelectric response remained even after annealing at temperatures above 636 °C.

Structure and Electrical Properties of Oxide Doped Rhombohedral Pb(Ni1/3Nb2/3)O3-PbTiO3 Ferroelectric Ceramics

0.7Pb(Ni1/3Nb2/3)O3-0.3PbTiO3 (0.7PNN-0.3PT) and 1 mol% La2O3-, Y2O3-, ZnO-, MnO2- and Nb2O5-doped 0.7PNN- 0.3PT ferroelectric ceramics were prepared by the conventional solid-state reaction method via the columbite precursor route. The ceramics sintered at 1180℃ exhibit pure rhombohedral perovskite structure except the Y2O3-doped 0.7PNN-0.3PT ceramics. The oxide-doped 0.7PNN-0.3PT ceramics exhibit rather homogeneous microstructure and improved densification, especially for the MnO2-and La2O3-doped 0.7PNN-0.3PT (defect) ceramics whose relative density is larger than 96%. All the above dopants decrease the dielectric loss of the 0.7PNN-0.3PT ceramics, whereas the values of the dielectric maximum (?m) and the temperature of ?m (Tm), and the character of dielectric response vary differently. ZnO and Nb2O5 doping increase remanent polarization Pr, and La2O3, ZnO, MnO2 and Nb2O5 doping decrease coercive field Ec of the 0.7PNN-0.3PT ceramics. Piezoelectric property is greatly improved by Y2O3, MnO2, Nb2O5 and ZnO doping, where the MnO2-doped 0.7PNN-0.3PT ceramics exhibit the largest value of piezoelectric constant d33, which reaches 191 pC/N.