High Qm Research Articles

AC poling of high Qm and low acoustic impedance Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3 single crystals produced by a solid-state crystal growth

The AC poling cycle dependence of Mn-doped Pb(Mg1/3Nb2/3)O3-0.3Pb(Zr.Ti)O3 (PMN-0.3PZT) single crystals (SC) produced via the solid-state crystal growth (SSCG) method was investigated. The piezoelectric strain and charge constants, d 33 ＝ 1130 pC/N, g 33 = 42.7 × 10−3 Vm/N, and mechanical quality factor Q m = 800 were obtained under conditions of 1 Hz, bipolar sine wave, 7.5 kV cm−1 electric field, and 6000 cycles. In contrast to the conventional Bridgman process SC, the low-density and high Q m SSCG SC necessitates a substantial number of AC cycles due to the presence of pores within the SC. In addition, the ACP SC showed a 13 °C increase in the phase change temperature T rt compared to the DC-poled SC. This information on ACP SSCG SCs with improved thermal stability, low acoustic impedance, and enhanced receiving efficiency attributable to high g 33 offers new insight into high-frequency ultrasonic devices.

Strong pinning effect on domains in piezoelectrics

In high-power applications, since mechanical losses in piezoelectric devices always result in considerable heat generation, the temperature stability of the mechanical quality factor (Qm) is particularly crucial and should be considered in real piezoelectric applications. Here, we propose a poling-aging-repoling strategy to make the defect dipoles aligned with the poling direction as much as possible, thereby resulting in the strong pinning of ferroelectric domains. A giant internal bias field Ei (11.6 kV cm−1 @ 1 Hz) and a high Qm (2074), accompanied by almost unchanged d33, are obtained in the composition of CuO-doped (K0.48Na0.52)0.94Li0.06Nb0.94Ta0.06O3 (KNNLT-Cu) ceramics with a diffused polymorphic phase transition. Furthermore, and this is more encouraging, the high electromechanical performance exhibits good temperature stability in the range from room temperature to 100 °C, suggesting that the thermal stability of Qm can be effectively improved by combining the strong pinning of defect dipoles with composition design and providing a way for the development and design of future high-power piezoelectric devices.

Crafting very low frequency magnetoelectric antenna via piezoelectric and electromechanical synergic optimization strategy

A boom in exploration for marine geology and ocean resources has resulted in a huge demand for radio navigation or special environment communications, in turn spurring the rapid development of portable underwater wireless communication technology. State of the art acoustic communication methods used today are plagued by substantial transmission delays, multipath effects, and doppler frequency shifts, among other challenges, thus impeding the advancement of underwater wireless communication technology. Low-frequency electromagnetic transmission has proven to be a prospective solution for underwater communication, but the conventional electrical antennas is too large for portable underwater wireless communication. Emergent magnetoelectric (ME) antennas driven by piezoelectric materials have become a promising solution for miniaturizing very low frequency (VLF) communication systems. Here, a theoretical model between the radiation performance and piezoelectric material properties of the ME antenna was conducted. Guide by the theory analysis, Pb(In1/2Nb1/2)O3-Pb(Mn1/3Sb2/3)O3-Pb(Zr0.49Ti0.51)O3 (PIN-PMS-PZT) piezoelectric ceramic simultaneous with high d33 and Qm (d33 ∼ 401, Qm ∼ 1510) has been designed to enhance the magnetoelectric radiation of the VLF ME antenna. The PIN-PMS-PZT based ME antenna achieves a large converse magnetoelectric response 1.78 Gs·cm/V in EMR, which is almost doubled to commercial PZT based ME antenna. More importantly, a VLF communication system was built based on the VLF antenna, which successfully transmitted digital signals using Amplitude-Shift-Keying (ASK) modulation. It is believed that the presented work could provide a theoretical basis and feasible technical path for the employment of ME antennas in the future.

Modified Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics with high d33，large Qm and high Tc

The development of piezoelectric ceramics with large piezoelectric coefficient (d33), high Curie temperature (Tc) and high mechanical quality factor (Qm) is still a key challenge for practical application for high-power device. Herein, a series of Sm3+ and Mn2+ ions co-doped 0.15Pb(Mg1/3Nb2/3)O3-(0.85-x)PbZrO3-xPbTiO3 ceramics were prepared by the solid-state sintering method. The optimum piezoelectric properties were achieved at x = 0.435 mol% with a large d33 ∼ 450 pC/N and a high Qm ∼ 1968 near the morphotropic phase boundary (MPB), and with high Tc ∼ 296 °C. The origin of this excellent piezoelectric properties was explained by the phase structure, piezoelectric and dielectric analysis. The composition near MPB region and the appearance of defect dipoles leaded to final excellent piezoelectric properties, and made a harmonization between d33, Tc and Qm. This work demonstrated a rational strategy to obtain large d33, high Tc and high Qm for high-power piezoceramics.

Enhancing the piezoelectric properties and thermal stability of PMN-PMS-PSZT high-power piezoelectric ceramics through defect engineering

The development of high-power piezoelectric ceramics with superior piezoelectric properties and broad temperature usage ranges is vital for the thriving progress of electromechanical applications. However, achieving high piezoelectricity, high mechanical quality factor, and temperature stability often presents a trade-off. In this study, we present an advanced ceramic material with excellent high-power piezoelectric properties and superior temperature stability. The piezoelectric coefficient d33 reaches 348 pC N−1, the electromechanical coupling factor kp is 54%, the mechanical quality factor Qm is 1501, the dielectric loss tanδ is 0.35%, and the d33 variation is less than 10% within 25–210 °C in 0.05Pb(Mg1/3Nb2/3)O3-0.05Pb(Mn1/3Sb2/3)O3-0.9Pb0.95Sr0.05(Zr0.48Ti0.52)O3 ceramic. The excellent piezoelectricity is attributed to the enhancement of intrinsic ionic displacement and reversible domains wall motion because of symmetry-conforming short-range distribution of oxygen vacancy, while the high Qm is a result of increased domain size and oxygen vacancy. The outstanding temperature stability is related to the stable non-180°domains structure due to the oxygen vacancy pinning effect. These properties hold great potential for advanced applications, particularly for piezoelectric high-power applications requiring constant d33 over a broad temperature range.

Mechanism and application of lead-free KNN-based ceramics with superior piezoelectricity

Piezoelectric ultrasonic energy harvesters (PUEHs) have recently attracted increasing attention. For minimizing the energy losses during energy transfer, it is crucial for core piezoelectric materials to maintain high piezoelectric coefficient (d33), mechanical quality factor (Qm), and piezoelectric voltage coefficient (g33). Herein, a simple way of hardening strategy improves the piezoelectric properties of KNN-based ceramics, combined with optimizing grain growth. The enhanced d33 (∼340 pC/N), high Qm (∼211) and TC (∼305 °C) are obtained simultaneously in this system, accompanied by superior d33×g33=8770×10−15 m2/N. Through variable temperature resonance test, the polarization rotation diversity caused by phase structure difference is found to closely related to the temperature stability of Qm value. A prototype of PUEH device was further designed and fabricated, with adjustable ultrasound-induced output voltage up to 8.2 V. Our work exhibits an effective way to improve performance of PUEHs by optimizing piezoelectric materials, which is helpful for further developing PUEHs.

Textured Potassium Sodium Niobate Lead-Free Ceramics with High d33 and Qm for Meeting High-Power Applications.

Potassium sodium niobate (KNN) lead-free piezoceramics have garnered significant attention for their environmentally friendly attributes, desired piezoelectric activity (d33), and high Curie temperature (Tc). However, the limited applicability of most KNN systems in high-power apparatus, including ultrasonic motors, transformers, and resonators, persists due to the inherent low mechanical quality factor (Qm). Herein, we proposed an innovative strategy for achieving high Qm accompanied by desirable d33 via synergistic chemical doping and texturing in KNN piezoceramics. Comprehensive electrical measurements along with quantitative structural characterization at multilength scales reveal that the excellent electromechanical properties (kp = 0.58, d33 ∼ 134 pC·N-1, Qm = 582, and Tc ∼ 415 °C) originate from the high <001> texturing degree, nanodomain, as well as acceptor hardening. Our findings provide an insight and guidance for achieving high-power performance in lead-free KNN-based piezoceramics, which were expected to be used in advanced transducer technology.

Well-balanced performance achieved in PZT piezoceramics via a multiscale regulation strategy.

Emerging high-power piezoelectric applications demand the development of piezoelectric materials featuring both a high mechanical quality factor (Qm) and a large piezoelectric coefficient (d33). However, it is widely accepted that an increase in d33 is usually accompanied with a decrease in Qm, and vice versa. Herein, a multiscale regulation strategy is proposed to improve Qm and d33 simultaneously from the perspectives of phase structure, ferroelectric domains, and lattice defects. A well-balanced combination of electromechanical performances with Qm = 726, d33 = 502 pC N-1, kp = 0.69, tan δ = 0.0024, and TC = 267 °C was obtained. Through structural characterization, it was observed that the morphotropic phase boundary and enhanced dispersion behavior lead to a lowered energy barrier, which contributes to polarization rotation and enhances piezoelectric performance. At the same time, the excellent piezoelectric performances also benefit from the highly oriented domain structure and small domain size after high-temperature poling. Furthermore, the segregation of Ba2+ causes A-site defects in the crystal lattice, accompanied with an increase in oxygen vacancies, which maintains the hardening effect of the ceramics. This study proposes a multiscale regulation strategy, providing insights for the design of high-power piezoelectric ceramics with high d33 and Qm.

Synchronous micromechanically resonant programmable photonic circuits

Programmable photonic integrated circuits (PICs) are emerging as powerful tools for control of light, with applications in quantum information processing, optical range finding, and artificial intelligence. Low-power implementations of these PICs involve micromechanical structures driven capacitively or piezoelectrically but are often limited in modulation bandwidth by mechanical resonances and high operating voltages. Here we introduce a synchronous, micromechanically resonant design architecture for programmable PICs and a proof-of-principle 1×8 photonic switch using piezoelectric optical phase shifters. Our design purposefully exploits high-frequency mechanical resonances and optically broadband components for larger modulation responses on the order of the mechanical quality factor Qm while maintaining fast switching speeds. We experimentally show switching cycles of all 8 channels spaced by approximately 11 ns and operating at 4.6 dB average modulation enhancement. Future advances in micromechanical devices with high Qm, which can exceed 10000, should enable an improved series of low-voltage and high-speed programmable PICs.

Origin of high comprehensive electromechanical properties of novel donor and acceptor–codoped PMN–30PT ceramics

Donor and acceptor–codoped PMN–30PT ceramics with 1–3 mol% Sm and 1 mol% Mn were fabricated via a two-step solid-state reaction. The crystal structure and electrical properties were investigated in detail. Donor Sm and acceptor Mn codoping substantially enhances the electromechanical, piezoelectric, and dielectric properties with a high piezoelectric coefficient d33 = 483–680 pC/N, a high mechanical quality factor Qm = 518–642, a high field-induced strain = 0.20%–0.24 %, and a low dielectric loss tan δ = 0.54%–0.69 %. X-ray diffraction and Raman spectra reveal the coexisting triple phase composition of the rhombohedral phase, tetragonal phase, and monoclinic polar nanoregions. Thermally stimulated depolarization current verifies the formation of various defect dipole clusters such as (MnTi″–VO··)×. With enhanced local structure heterogeneity induced by Sm, the phase composition and defect chemistry are regarded as the origin of such high comprehensive performance.

Achieving combinatory “soft” and “hard” piezoelectric properties in textured ceramics via exploring single‐crystal‐like electrostriction

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

KNN-Based Lead-Free Piezoelectric Ceramics with High Qm and Enhanced d33 via a Donor-Acceptor Codoping Strategy.

The wide application of KNN-based lead-free piezoelectric ceramics is constrained by the contradictory relationship between its mechanical quality factor and piezoelectric constant. From an application point of view, searching for chemical composition with enhanced piezoelectric constant (d33) and mechanical quality factor (Qm) is one of the key points of KNN-based ceramics. In this work, KNN-based ceramics with enhanced d33 and high Qm values were obtained by the solid solution method via a donor-acceptor codoping strategy. The donor dopant Ho3+ enhanced d33 values by refining the domain size, while the acceptor dopant (Cu1/3Nb2/3)4+ improved Qm by the formation of defect dipoles. The composition (KNN-5Ho-4CN) exhibits optimal integrated performances, of which d33, Qm, and TC values are 120 pC/N, 850, and 392 °C, respectively. Moreover, the temperature coefficient of resonant frequency (TCF = -429 ppm/K) indicates that KNN-5Ho-4CN ceramic has good temperature stability. This work provides a new insight for developing KNN-based ceramics with enhanced d33 and high Qm.

Grain Boundary Diffusion Hardening in Potassium Sodium Niobate‐Based Ceramics with Full Gradient Composition and High Piezoelectricity

AbstractReducing mechanical losses and suppressing self‐heating are critical characteristics for high‐power piezoelectric applications. For environmentally friendly Pb‐free piezoelectric ceramics, traditional acceptor doping or annealing treatments have successfully improved the mechanical quality factor (Qm) based on a ceramic matrix with a poor piezoelectric coefficient (d33&lt;100 pC/N). Nevertheless, a ceramic with high Qm and d33 values has not been reported owing to the inverse relationship between Qm and d33. Herein, a novel hardening method called grain boundary diffusion is used to develop Pb‐free potassium sodium niobate ceramics, where Qm increased by more than two‐fold (from 51 to 132) and a high d33 value (d33 = 360 pC/N) is maintained. Significantly, d33 retained 98% of its initial value after 180 days, exhibiting improved aging stability. The established properties are associated with the formation of the core‐shell microstructure and the full gradient composition distribution using structural characterizations and phase‐field simulations, where the core maintains a high d33 and the shell provides a hardening effect. The novel hardening effect in piezoelectric materials, known as grain boundary diffusion hardening, highlights the enhancement of the mechanical quality factor with high piezoelectricity, providing a new paradigm for the design of functional materials.

Microbial, physical and chemical indicators together reveal soil health changes related to land cover types in the southern European sites under desertification risk

Soil microbial communities, which play a key role in the provision of essential ecosystem services, are significantly influenced by several physical and chemical soil properties that may change with land management. This study explores the effect of different land cover types (coniferous tree stands, broad-leaved stands, shrublands, pastures/grasslands and croplands) on physical, chemical and microbial properties (all contributing to soil health) in southern European areas under moderate-high desertification risk selected in Italy, Spain and Portugal. In sites that differ in land cover, we determined microbial biomass (Cmic), activity and indices of microbial metabolism including Cmic/Corg ratio, metabolic quotient (qCO2) and quotient of mineralization (qM). Soil physical and chemical properties were also measured, comprising bulk density (BD), water content (WC), pH, cation exchange capacity (CEC), total organic C (Corg) and some of its labile fractions, extractable C (Cext) and mineralizable C (Cmin), total N content and C/N. Results showed that land cover type played a strong role in determining magnitude of microbial variables with biomass and activity being higher under coniferous tree cover than in other land covers, according to trends in WC, CEC, Corg, Cext, Cmin, N, C/N. Compared to land cover, aridity index had lower effect on investigated variables. In comparison to sites with higher Corg content, sites with lower Corg content (most croplands) tended to lose C more rapidly, as suggested by high qM values, except for Spanish acidic soils. Therefore, urgent actions must be taken to counteract the tendency of C-poorer soils to lose C, promoting land cover types that facilitate soil recovery by ensuring denser and more continuous soil cover over time. We also identified a minimum set of soil variables that provide information on soil health changes in both short term (microbial variables) and longer term (physical and chemical variables) in areas under desertification risk.

Sm2O3 and MnO2 codoped PMN-PZT ceramics with both high mechanical quality factor and piezoelectric properties

For lead-based ceramics used in high-power devices, it is essential that they possess both a high mechanical quality factor (Qm) and a large piezoelectric coefficient (d33). Unfortunately, Qm is inversely proportional to d33 for piezoelectric ceramics, which the limits their actual application. If suitable acceptor and donor dopants can be added in piezoelectric ceramics, it is rational to achieve high Qm and large d33 simultaneously. Herein, we tried to achieve both a high mechanical quality factor and large piezoelectric activity in 0.47 pb(Mg1/2Nb2/3)O3-0.18PbZrO3-0.35PbTiO3 (PMN-PZT) ceramics via Sm2O3 and MnO2 co-doing. A range of xMn-2Sm-PMN-PZT ceramics were fabricated by the traditional sintering method. An optimal performance was attained in 4Mn-2Sm-PMN-PZT ceramics with Qm = 1720, d33 = 450 pC/N, ε = 2720 and kp = 0.54. The high Qm is related to the presence of defect dipoles as a result of MnO2 doping and the large piezoelectric activity is due to the doping of Sm2O3.

Outstanding electromechanical performance in piezoelectric ceramics via synergistic effects of defect engineering and domain miniaturization

Piezoelectric ceramics with high mechanical quality factor Qm and large piezoelectric coefficient d33 are urgently required for advanced piezoelectric applications. However, obtaining both of these properties simultaneously remains a difficult challenge due to their mutually restrictive relationship. Here 0.5Pb(Ni1/3Nb2/3)O3–0.5Pb(Zr0.3Ti0.7)O3 piezoceramic with tetragonal (T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions. The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of Ps, restrict domain wall motion and improve Qm. At the same time, the substituted Mn ions will introduce local random field, destroying the long-range ordering of ferroelectric domain and reducing domain size. The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d33. Guided by this strategy, Qm has increased by more than 10 times and d33 has only decreased by about 25%. The optimized electromechanical performance with Qm = 822, d33 = 502 pC/N, kp = 0.55 and tanδ = 0.0069 can be obtained in the present study.

Enhancing Electromechanical Properties of PZT-Based Piezoelectric Ceramics by High-Temperature Poling for High-Power Applications.

Defect engineering is a proven method to tune the properties of perovskite oxides. In demanding high-power piezoelectric ceramic applications, acceptor doping is the most effective method to harden ceramics, but it inevitably degrades the ceramics' electromechanical properties. Herein, a poling method based on acceptor doping, namely, high-temperature poling, is implemented by applying an electric field above the Curie temperature for poling to achieve a balance of the properties of piezoelectric coefficient d33 and mechanical quality factor Qm. After high-temperature poling, the piezoelectric property of 0.6 mol % Mn-doped Pb0.92Sr0.08(Zr0.533Ti0.443Nb0.024)O3 is d33 = 483 pC/N and Qm = 448. Compared with the traditional poling, the piezoelectric coefficient d33 of the high-temperature poling ceramics increased by approximately 40%, and Qm also increased by nearly 18%. Therefore, high d33 and Qm were exhibited by our PZT piezoelectric ceramics. Rayleigh's law analysis, XRD, and transmission electron microscopy analysis show that, after high-temperature poling, the considerably increased d33 is related to the large increase in the reversible domain wall motion in the intrinsic effect, while the slightly increased Qm is related to the inhibited irreversible domain wall motion in the extrinsic effect. This study reports a method for high-temperature poling and provides insights into the design of high-power piezoelectric ceramics with high d33 and Qm.

Sm and Mn co-doped PMN-PT piezoelectric ceramics: Defect engineering strategy to achieve large d33 and high Qm

• A strategy of donor-acceptor (Sm-Mn) co-doping defect engineering is introduced into the PMN-PT to improve the d 33 and Q m simultaneously. • The Optimal performances were obtained in PMN-30PT: 2.5Sm, 1-2Mn ceramics, with d 33 =860-543 pC/N, Q m =495-754, and tan δ =0.0055-0.0086. • This high performance originates from the combined effects of ( Mn Ti ″ − V o • • ) x defect dipoles and the local structural heterogeneity. PbTiO 3 -based piezoelectric ceramics are key materials for developing various electromechanical transducers. For high-power ultrasonic transducers, piezoelectric ceramics are required to possess large piezoelectric coefficient ( d 33 ) and high mechanical quality factor ( Q m ). Although acceptor dopants can improve Q m , they also deteriorate d 33 . If suitable piezoelectricity-beneficial donor dopants can be introduced into acceptor-doped ceramics, it is very possible to obtain large d 33 and high Q m simultaneously in donor and acceptor co-doped ceramics. In this work, a series of x mol% Sm and y mol% Mn co-doped Pb(Mg 1/3 Nb 2/3 )O 3 -30PbTiO 3 (PMN-30PT: x Sm, y Mn) ceramics were prepared by the solid-phase sintered method. The crystal structure, local domain structure and electromechanical properties were systematically analyzed. Optimal performances were obtained in PMN-30PT: 2.5Sm, 1-2Mn ceramics with d 33 =860-543 pC/N, Q m =495-754, and dielectric loss tan δ =0.0055-0.0086. This high performance originates from the combined effects of ( Mn Ti ″ − V o • • ) × defect dipoles and the local structural heterogeneity.

Enhanced electromechanical performance of PSZT–PMS–PFW through morphotropic phase boundary design and defect engineering

It is desirable but challenging to explore piezoelectric ceramics with high mechanical quality factor Qm and large mechanical piezoelectric coefficient d33 simultaneously because of the intrinsic restriction between d33 and high Qm.

Hardening Effect in Lead-Free KNN-Based Piezoelectric Ceramics with CuO Doping.

As the most promising lead-free piezoelectric ceramics to replace lead zirconate titanate (PZT) ceramics, potassium sodium niobate (KNN) ceramics have been widely studied for their application prospects in various electronic devices. Increasing Qm while maintaining a high piezoelectric activity is quite important for piezoelectric ceramics applied in ultrasonic devices. A KNN-based ceramic with high d33 and Qm is prepared by a conventional solid-state technique to construct polycrystalline phase boundaries and induce defect dipoles. The best overall performance can reach d33 = 260 pC/N, Qm = 210, and TC = 293 °C. The temperature dependence of the relevant parameters is tested, where Qm increases but d33 decreases with the rise of temperature accompanied by escaping ferroelectric boundary, which shows that the polarization rotation plays an important role in the two parameters. The hardening effect of KNN-based ceramics with CuO doping is further studied by first-principles calculations, demonstrating that the Cu doping strongly disturbs the ferroelectric order, but the formation of defect dipoles could stabilize the ferroelectric order. It is illustrated that defect dipoles always find their ground state at the site near the domain walls and the oriented defect dipoles hinder the polarization rotation severely, confirming the role of the defect dipoles in KNN-based materials.