Beam-Mode Piezoelectric Properties of Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Single Crystals for Medical Linear Array Applications

In this work, the dielectric and beam-mode piezoelectric properties of ternary 0.35Pb(In_1/2Nb_1/2)O₃-0.35Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ (PIMNT35/35/30) piezoelectric single crystals were investigated. The Curie temperature (T _C) and rhombohedral-to-tetragonal phase-transition temperature (T _rt) are 187°C and 127°C, about 30°C higher than those of PMNT crystals. The beam-mode coupling coefficient k ₃₃ ^w was found to be 90.3%. Furthermore, 3.5-MHz linear arrays based on PIMNT35/35/30 crystals and Pb(Zr_1−x Ti _x )O₃ ceramic (PZT-5H) were simulated using PiezoCAD software. The results indicate that the sensitivity and −6 dB bandwidth of a PIMNT35/35/30 transducer would be approximately 4 dB and 20% higher, respectively, compared with a traditional PZT transducer.     

The Contributions of Polar Nanoregions to the Dielectric and Piezoelectric Responses in Domain‐Engineered Relaxor‐PbTiO3 Crystals

The existence of polar nanoregions is the most important characteristic of relaxor‐based ferroelectric materials. Recently, the contributions of polar nanoregions to the shear piezoelectric property of relaxor‐PbTiO₃ (PT) crystals are confirmed in a single domain state, accounting for 50%–80% of room temperature values. For electromechanical applications, however, the outstanding longitudinal piezoelectricity in domain‐engineered relaxor‐PT crystals is of the most significance. In this paper, the contributions of polar nanoregions to the longitudinal properties in [001]‐poled Pb(Mg_1/3Nb_2/3)O₃‐0.30PbTiO₃ and [110]‐poled Pb(Zn_1/3Nb_2/3)O₃‐0.15PbTiO₃ (PZN‐0.15PT) domain‐engineered crystals are studied. Taking the [110]‐poled tetragonal PZN‐0.15PT crystal as an example, phase‐field simulations of the domain structures and the longitudinal dielectric/piezoelectric responses are performed. According to the experimental results and phase‐field simulations, the contributions of polar nanoregions (PNRs) to the longitudinal properties of relaxor‐PT crystals are successfully explained on the mesoscale, where the PNRs behave as “seeds” to facilitate macroscopic polarization rotation and enhance electric‐field‐induced strain. The results reveal the importance of local structures to the macroscopic properties, where a modest structural variation on the nanoscale greatly impacts the macroscopic properties.     

High electric-field-induced strain beahvior of single-crystal Pb(Mg<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3</Subscript>-xPbTiO<Subscript>3</Subscript> multilayer piezoelectric actuators

Two 10-mm-long multilayer prototype actuators were fabricated by a stack method using 55 pieces of 5 mm×5 mm×0.15 mm Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ (PMNT) single crystals and PZT-5A ceramics, respectively. The strain values for PMNT multilayer piezoelectric actuators are twice those of PZT-5A multilayer actuators, and 20.8-μm displacements can be achieved at the same E-field of 15 kV/cm. Although thermal and electrical history markedly impact dielectric and piezoelectric performance of PMNT crystals, the PMNT multilayer actuator can still achieve large displacements with approximately linear behavior below 60°C. Broad stable dynamic displacement characteristic and fast displacement response make the new-type actuators promising candidates for the application in new-generation high-performance solid-state actuators.     

Giant Piezoelectric Coefficients in Relaxor Piezoelectric Ceramic PNN‐PZT for Vibration Energy Harvesting

It is well known that the piezoelectric performance of ferroelectric Pb(Zr,Ti)O₃ (PZT) based ceramics is far inferior to that of ferroelectric single crystals due to ceramics' polycrystalline nature. Herein, it is reported that piezoelectric stress coefficient e₃₃ = 39.24 C m^?2 (induced electric displacement under applied strain) in the relaxor piezoelectric ceramic 0.55Pb(Ni_1/3Nb_2/3)O₃–0.135PbZrO₃–0.315PbTiO₃ (PNN‐PZT) prepared by the solid state reaction method exhibits the highest value among various reported ferroelectric ceramic and single crystal materials. In addition, its piezoelectric coefficient d₃₃* = 1753 pm V^?1 is also comparable with that of the commercial Pb(Mg_1/3Nb_2/3)O₃‐PbTiO₃ (PMN‐PT) piezoelectric single crystal. The PNN‐PZT ceramic is then assembled into a cymbal energy harvester. Notably, its maximum output current at the acceleration of 3.5 g is 2.5 mA_pp, which is four times of the PMN‐PT single crystal due to the large piezoelectric e₃₃ constants; while the maximum output power is 14.0 mW, which is almost the same as the PMN‐PT single crystal harvester. The theoretical analysis on force‐induced power output is also presented, which indicates PNN‐PZT ceramic has great potential for energy device application.     

Mechanical Confinement: An Effective Way of Tuning Properties of Piezoelectric Crystals

Using <001>‐oriented Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ ferroelectric single crystals as a model material, the impact of mechanical confinements on polarization hysteresis, coercive field, and remanent polarization of relaxor‐based piezocrystals is investigated. Comparative studies are made among rhombohedral and tetragonal single crystals, as well as a polycrystalline ceramic, under uniaxial and radial compressive pre‐stresses. The dramatic changes observed are interpreted in terms of the piezoelectric effect and possible phase transitions for rhombohedral crystals, and ferroelastic domain switching and the piezoelectric effect for tetragonal crystals. Under radial compressive stresses, the coercive field for the rhombohedral crystal is observed to increase to 0.67 kV/mm and that for the tetragonal crystal is increased to 0.78 kV/mm. This is a 200% increase relative to the unstressed condition. The results demonstrate a general and effective approach to overcome the drawback of low coercive fields in these relaxor‐based ferroelectric crystals, which could help facilitate widespread implementation of these piezocrystals in engineering devices.     

Effect of sintering and poling conditions on the properties of [Pb,Sr][(Zr,Ti)(Zn,Nb)(Mg,Nb)]O3 piezoelectric ceramics system

The (Pb,Sr)[(Zr,Ti)(Zn,Nb)(Mg,Nb)]O₃ piezoelectric ceramic system with compositions close to the morphotropic phase boundary (MPB) was studied. The dielectric and piezoelectric properties of the system Pb_0.96Sr_0.04[(Zr_1-yTi_y)_0.74(Zn_1/3Nb_2/3)_0.06(Mg_1/3Nb_2/3)_0.20]O₃ were investigated, where the compositions of 0.44 ≤y ≤ 0.60 were selected. From the results of XRD and piezoelectric measurement, it was supposed that the composition withy = 0.50 - 0.51 corresponded to MPB between tetragonal and pseudocubic phase. By the way of the variation of the fabrication process, the influence of sintering and poling processes on the properties of the ceramic were studied, and we expected to find the optimal conditions of these processes. Some developed phenomena or models were introduced. After the optimal choice of the process conditions, the planar coupling factor close to 0.73 and the dielectric constant close to 3000 can be approached simultaneously in this multicomponent system.     

Inside Front Cover: Perfect Bi4Ti3O12 Single‐Crystal Films via Flux‐Mediated Epitaxy (Adv. Funct. Mater. 4/2006)

Flux‐mediated epitaxy has been developed for ferroelectric Bi₄Ti₃O₁₂ single‐crystal film growth, as shown on the inside cover. The key point is the selection of an appropriate flux material. A combinatorial high‐throughput screening technique reported by Matsumoto and co‐workers on p. 485 has led to the successful discovery of the novel flux composition, Bi–Cu–O, for Bi₄Ti₃O₁₂ single‐crystal film growth. This flux‐mediated epitaxy is not limited to oxide epitaxy, but is also widely applicable to various promising materials for the realization of non‐Si‐based electronics, such as nitrides, carbides, and halides. Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi₄Ti₃O₁₂ and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi₄Ti₃O₁₂ films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi₄Ti₃O₁₂ single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi₄Ti₃O₁₂ film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required.     

Perfect Bi4Ti3O12 Single‐Crystal Films via Flux‐Mediated Epitaxy

Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional‐device applications. Bi₄Ti₃O₁₂ and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random‐access memories. However, it has been difficult thus far for Bi₄Ti₃O₁₂ films to satisfy such requirements when formed using vapor‐phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux‐mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi‐component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi–Cu–O for Bi₄Ti₃O₁₂ single‐crystal film growth. The perfect single‐crystal nature of the stoichiometric Bi₄Ti₃O₁₂ film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single‐crystal oxide films via vapor‐phase epitaxy, even if volatile constituents are required.     

Investigation of Structural and Electrical Properties of B-Site Complex Ion (Mg1/3Nb2/3)4+-Modified High-Curie-Temperature BiFeO3-BaTiO3 Ceramics

B-site complex ion (Mg_1/3Nb_2/3)-modified high-temperature ceramics 0.71BiFeO₃-0.29BaTi_1?x (Mg_1/3Nb_2/3) _x O₃ (BF-BTMNx) have been fabricated by the conventional solid-state reaction method. The compositional dependence of the?phase structure, electrical properties, and depolarization temperature of the ceramics was studied. The main phase structure of BF-BTMNx ceramics is perovskite phase with pseudocubic symmetry. The experimental results show that the dielectric and piezoelectric properties, and temperature stability strongly depend on the (Mg_1/3Nb_2/3)⁴⁺ content. The optimum (Mg_1/3Nb_2/3) content enhances the piezoelectric properties, Curie temperature, and depolarization temperature. The ceramic with x = 1% exhibited enhanced electrical properties of d ₃₃ = 158 pC/N and k _p = 0.322, combined with high-temperature stability with Curie temperature of T _c = 453°C and depolarization temperature of T _d = 400°C. These results show that the ceramic with x = 1% is a promising lead-free high-temperature piezoelectric material.     

Complete Set of Material Constants of ?011?-Poled Rhombohedral Single-Crystal 0.25Pb(In1/2Nb1/2)O3-0.47Pb(Mg1/3Nb2/3)O3-0.28PbTiO3

The complete set of elastic, dielectric, and piezoelectric constants of a 0.25Pb(In_1/2Nb_1/2)O₃-0.47Pb(Mg_1/3Nb_2/3)O₃-0.28PbTiO₃ ternary relaxor ferroelectric single crystal after 〈011〉 poling was determined by ultrasonic and resonance methods. It exhibited a rhombohedral structure as determined by powder x-ray diffraction (XRD) and x-ray fluorescence (XRF) analysis. The electromechanical coupling factor k ₁₅ and piezoelectric coefficient d ₁₅ for shear mode are 0.93 pC/N and 2658 pC/N, and k ₃₂ and d ₃₂ for transverse mode are 0.91 pC/N and -1337 pC/N, respectively. More importantly, the rhombohedral to orthorhombic phase-transition temperature is much higher than that of PZN-0.07PT or PMN-0.29PT.     

Relaxor Behavior in Ordered Lead Magnesium Niobate (PbMg1/3Nb2/3O3) Thin Films

The local compositional heterogeneity associated with the short‐range ordering of Mg and Nb in PbMg_1/3Nb_2/3O₃ (PMN) is correlated with its characteristic relaxor ferroelectric behavior. Fully ordered PMN is not prepared as a bulk material. This work examines the relaxor behavior in PMN thin films grown at temperatures below 1073 K by artificially reducing the degree of disorder via synthesis of heterostructures with alternate layers of Pb(Mg_2/3Nb_1/3)O₃ and PbNbO₃, as suggested by the random‐site model. 100 nm thick, phase‐pure films are grown epitaxially on (111) SrTiO₃ substrates using alternate target timed pulsed‐laser deposition of Pb(Mg_2/3Nb_1/3)O₃ and PbNbO₃ targets with 20% excess Pb. Selected area electron diffraction confirms the emergence of (1/2, 1/2, 1/2) superlattice spots with randomly distributed ordered domains as large as ≈150 nm. These heterostructures exhibit a dielectric constant of 800, loss tangents of ≈0.03 and 2× remanent polarization of ≈11 µC cm^?2 at room temperature. Polarization–electric field hysteresis loops, Rayleigh data, and optical second‐harmonic generation measurements are consistent with the development of ferroelectric domains below 140 K. Temperature‐dependent permittivity measurements demonstrate reduced frequency dispersion compared to short range ordered PMN films. This work suggests a continuum between normal and relaxor ferroelectric behavior in the engineered PMN thin films.     

超快激光制备高频1-3型PIN-PMN-PT复合材料超声换能器

与其他压电材料相比,1-3型压电单晶复合材料具有优异的压电性能和更匹配的声学特性,更有利于制备出性能优异的超声换能器。该文通过有限元软件COMSOL对复合材料的振动模态及阻抗特性进行了系统的研究,同时采用皮秒激光制备了高频1-3型Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(PIN-PMN-PT)铁电单晶/环氧树脂复合材料,并进行了性能表征。该1-3复合材料机电耦合系数为0.65,声阻抗为19.96 MRayls。该复合材料可用于制备高频超声换能器,结果表明,换能器中心频率为17.68 MHz,-6 dB带宽为84.38%,插入损耗为-25.4 dB。     

Long‐Range Nonvolatile Electric Field Effect in Epitaxial Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Heterostructures

One of the ideal candidates of using electric field to manipulate magnetism is the recently developed multiferroics with emergent coupling of magnetism and electricity, particularly in synthesizing artificial nanoscale ferroelectric and ferromagnetic materials. Here, a long‐range nonvolatile electric field effect is investigated in Fe/Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃ heterostructure using the dependence of the magnon‐driven magnetoelectric coupling on the epitaxial Fe thin film (4–30 nm) thickness at room temperature using measurements based on the ferromagnetic resonance. The magnon‐driven magnetoelectric coupling tuning of the ferromagnetic resonance field shows a linear response to the electric field, with a resonance field shift that occurs under both positive and negative remanent polarizations, and demonstrates nonvolatile behavior. Moreover, the spin diffusion length of the epitaxial Fe thin film of ≈9 nm is obtained from the results that the change of the cubic magnetocrystalline anisotropy field under different electric fields varies with Fe thickness. These results are promising for the design of future multiferroic devices.     

Sustainable Vibration Energy Harvesting Based on Zr‐Doped PMN‐PT Piezoelectric Single Crystal Cantilevers

In this paper, we present the results of a preliminary study on the piezoelectric energy harvesting performance of a Zr‐doped PbMg_1/3Nb_2/3O₃‐PbTiO₃ (PMN‐PZT) single crystal beam. A novel piezoelectric beam cantilever structure is used to demonstrate the feasibility of generating AC voltage during a state of vibration. The energy‐harvesting capability of a PMN‐PZT beam is calculated and tested. The frequency response of the cantilever device shows that the first mode resonance frequency of the excitation model exists in the neighborhood of several hundreds of hertz, which is similar to the calculated value. These tests show that several significantly open AC voltages and sub‐mW power are achieved. To test the possibility of a small scale power source for a ubiquitous sensor network service, energy conversion and the testing of storage experiment are also carried out.     

Effects of Ta2O5/Y2O3 Codoping on the Microstructure and Microwave Dielectric Properties of Ba(Co0.56Zn0.40)1/3Nb2/3O3 Ceramics

The effects of Ta₂O₅/Y₂O₃ codoping on the microstructure and microwave dielectric properties of Ba(Co_0.56Zn_0.40)_1/3Nb_2/3O₃-xA-xB (A = 0.045 wt.% Ta₂O₅; B = 0.113 wt.% Y₂O₃) ceramics (x = 0, 1, 2, 4, 8, 16, 32) prepared according to the conventional solid-state reaction technique were investigated. The x-ray diffraction (XRD) results showed that the main crystal phase in the sintered ceramics was BaZn_0.33Nb_0.67O₃-Ba₃CoNb₂O₉. The additional surface phase of Ba₈CoNb₆O₂₄ and trace amounts of Ba₅Nb₄O₁₅ second phase were present when Ta₂O₅/Y₂O₃ was added to the ceramics. The 1:2 B-site cation ordering was affected by the substitution of Ta⁵⁺ and Y³⁺ in the crystal lattice, especially for x = 4. Scanning electron microscopy (SEM) images of the optimally doped ceramics sintered at 1340°C for 20 h showed a compact microstructure with crystal grains in dense contact. Though the dielectric constant increased with the x value, appropriate addition would result in a tremendous modification of the Q × f and τ _f values. Excellent microwave dielectric properties (ε _r = 35.4, Q × f = 62,993 GHz, and τ _f  = 2.6 ppm/°C) were obtained for the ceramic with x = 0.4 sintered in air at 1340°C for 20 h.     

Engineering of Self‐Assembled Domain Architectures with Ultra‐high Piezoelectric Response in Epitaxial Ferroelectric Films

Substrate clamping and inter‐domain pinning limit movement of non‐180° domain walls in ferroelectric epitaxial films thereby reducing the resulting piezoelectric response of ferroelectric layers. Our theoretical calculations and experimental studies of the epitaxial PbZr_xTi_1–xO₃ films grown on single crystal SrTiO₃ demonstrate that for film compositions near the morphotropic phase boundary it is possible to obtain mobile two‐domain architectures by selecting the appropriate substrate orientation. Transmission electron microscopy, X‐ray diffraction analysis, and piezoelectric force microscopy revealed that the PbZr_0.52Ti_0.48O₃ films grown on (101) SrTiO₃ substrates feature self‐assembled two‐domain structures, consisting of two tetragonal domain variants. For these films, the low‐field piezoelectric coefficient measured in the direction normal to the film surface (d₃₃) is 200 pm V^–1, which agrees well with the theoretical predictions. Under external AC electric fields of about 30 kV cm^–1, the (101) films exhibit reversible longitudinal strains as high as 0.35 %, which correspond to the effective piezoelectric coefficients in the order of 1000 pm V^–1 and can be explained by elastic softening of the PbZr_xTi_1–xO₃ ferroelectrics near the morphotropic phase boundary.     

脉冲掺钛蓝宝石激光器的输出特性研究

利用我国三个单位生长的晶体对脉冲运转的掺钛蓝宝石激光器的输出特性进行了初步的较系统的实验研究,对我国自己生长的不同晶体的激光性能进行了初步比较,结果与理论基本相符。     

Layered Orthorhombic Nb2O5@Nb4C3Tx and TiO2@Ti3C2Tx Hierarchical Composites for High Performance Li‐ion Batteries

Engineering electrode nanostructures is critical in developing high‐capacity, fast rate‐response, and safe Li‐ion batteries. This study demonstrates the synthesis of orthorhombic Nb₂O₅@Nb₄C₃T_x (or @Nb₂CT_x) hierarchical composites via a one‐step oxidation —in flowing CO₂ at 850 °C —of 2D Nb₄C₃T_x (or Nb₂CT_x) MXene. The composites possess a layered architecture with orthorhombic Nb₂O₅ nanoparticles decorated uniformly on the surface of the MXene flakes and interconnected by disordered carbon. The composites have a capacity of 208 mAh g^?1 at a rate of 50 mA g^?1 (0.25 C) in 1–3 V versus Li⁺/Li, and retain 94% of the specific capacity with 100% Coulombic efficiency after 400 cycles. The good electrochemical performances could be attributed to three synergistic effects: (1) the high conductivity of the interior, unoxidized Nb₄C₃T_x layers, (2) the fast rate response and high capacity of the external Nb₂O₅ nanoparticles, and (3) the electron “bridge” effects of the disordered carbon. This oxidation method was successfully extended to Ti₃C₂T_x and Nb₂CT_x MXenes to prepare corresponding composites with similar hierarchical structures. Since this is an early report on producing this structure, there is much room to push the boundaries further and achieve better electrochemical performance.     

High‐Performance [001]c‐Textured PNN‐PZT Relaxor Ferroelectric Ceramics for Electromechanical Coupling Devices

[001]_C‐Textured 0.55Pb(Ni_1/3Nb_2/3)O₃–0.15PbZrO₃–0.3PbTiO₃ (PNN‐PZT) ceramics are prepared by the templated grain‐growth method using BaTiO₃ (BT) platelet templates. Samples with different template contents are fabricated and compared in terms of texture fraction, microstructure, and piezoelectric, ferroelectric and dielectric properties. High piezoelectric performance (d₃₃ = 1210 pC N^?1, d₃₃* = 1773 pm V^?1 at 5 kV cm^?1) and high figure of merit g₃₃?d₃₃ (21.92 × 10^?12 m² N^?1) are achieved in the [001]_C‐textured PNN‐PZT ceramic with 2 vol% BaTiO₃ template, for which the texture fraction is 82%. In addition, domain structures of textured PNN‐PZT ceramics are observed and analyzed, which provide clues to the origin of the giant piezoelectric and electromechanical coupling properties of PNN‐PZT ceramics.     

New dielectric material system of Nd(Mg1/2Ti1/2)O3–CaTiO3 at microwave frequency

The microwave dielectric properties of (1 − x)CaTiO₃–xNd(Mg_1/2Ti_1/2)O₃ (0.1  x  1.0) ceramics prepared by the conventional solid state method have been investigated. The system forms a solid solution throughout the entire compositional range. The dielectric constant decreases from 152 to 27 as x varies from 0.1 to 1.0. In the (1 − x)CaTiO₃–xNd(Mg_1/2Ti_1/2)O₃ system, the microwave dielectric properties can be effectively controlled by varying the x value. At 1400 °C, 0.1CaTiO₃–0.9Nd(Mg_1/2Ti_1/2)O₃ has a dielectric constant (ε_r) of 42, a Q × f value of 35 000 GHz and a temperature coefficient of resonant frequency (τ_f) of −10 ppm/°C. As the content of Nd(Mg_1/2Ti_1/2)O₃ increases, the highest Q × f value of 43 000 GHz for x = 0.9 is achieved at the sintering temperature 1500 °C.