Electromechanical properties of Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) single crystals

The Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) (PIN-PMN-PT) crystals were studied as function of phase and orientation. The properties, including the Curie temperature T(C), ferroelectric-ferroelectric phase transition temperature T(R∕O-T), coercive field, and piezoelectric∕dielectric responses, were systematically investigated with respect to the composition of PIN-PMN-PT crystals. The Curie temperature T(C) was found to increase from 160 to 220 °C with ferroelectric-ferroelectric phase transition temperature T(R-T) and T(O-T) being in the range of 120-105 °C and105-50 °C, respectively. The piezoelectric activity of PIN-PMN-PT crystals was analyzed by Rayleigh approach. The ultrahigh piezoelectric response for domain engineered [001] (1600-2200 pC∕N) and [011] (830-1550 pC∕N) crystals was believed to be mainly from the intrinsic contribution, whereas the enhanced level of piezoelectric and dielectric losses at the compositions around morphotropic phase boundaries (MPBs) was attributed to the phase boundaries motion.     

Characterization of flux-grown PZN-PT single crystals for high-performance piezo devices

Relaxor ferroelectric Pb(Zn(1/3)Nb(2/3))O(3-x)PbTiO(3) (PZN-PT) and Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3)(PMN-PT) single crystals are the potential candidates for future high-performance piezoelectric devices due to their exceptionally high dielectric and piezoelectric properties. Characterization on flux-grown PZN-PT single crystals of different orientations revealed that PZN-(6-7)%PT single crystals show good homogeneity in dielectric and electromechanical properties and composition. When poled in [001] direction, these crystals exhibit high longitudinal-mode properties with dielectric constant (K(T)) approximately equal to 7000, piezoelectric coefficients (d(33)) approximately equal to 2800 pC/N, and electromechanical coupling factors (k(33)) > or = 0.92. For [011]-cut crystals, optimally poled PZN-7%PT single crystal exhibits very high transverse-mode dielectric and piezoelectric properties with K(T) > or = 5000, d(32) approximately equal to -3800 pC/N and k(32) > or = 0.90. [011]- poled PZN 6%PT has d(32) approximately equal to -3000 pC/N and comparable k(32) and K(T) values. In comparison with melt-grown PMNPT single crystals, flux-grown PZN-PT single crystals show good compositional homogeneity, superior and consistent dielectric and electromechanical properties, and higher depolarization temperatures (TDP).     

Microstructural and piezoelectric properties of low temperature sintering PMN-PZT ceramics with the amount of Li2CO3 addition

PMN-PZT ceramics doped with Li₂CO₃ and Bi₂O₃ as sintering aids were manufactured in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, and their micro structural, dielectric and piezoelectric properties were investigated. The sintering aids were proved to lower the sintering temperature of doped PMN-PZT ceramics due to the effect of LiBiO₂ liquid phase. Optimal values for multilayer piezoelectric transformer application, such as electromechanical coupling factor (k_p) of 0.50, mechanical quality factor (Q_m) of 2264, and dielectric constant (K) of 1216, and curie temperature (T_c) of 317 °C were found at 0.1 wt.% Li₂CO₃ added ceramics sintered at 940 °C.     

Modified single crystals for high-power underwater projectors

Underwater electroacoustic projectors using single crystals based on the lead magnesium niobate-lead titanate (PMNT) composition were investigated. The large electromechanical coupling coefficient (k(33) > 0.90) and piezoelectric coefficient (d(33) > 1500 pC/N) of PMNT have been demonstrated to improve transducer bandwidth and source level relative to conventional piezoelectric ceramics. The low mechanical quality factor (Q(M) < 200) and low temperature stability (T(RT) < 95°C) of PMNT, however, limit its utility in high-power, high-duty-cycle applications. Use of modified single crystals was shown to result in transducers which exhibit up to 5 dB improvement in source level over PMNT when operated at resonance. Compared with a PZT4 transducer, these modified crystals offer similar source level and power handling capability at resonance, but the available bandwidth is doubled and a 6 dB improvement in maximum source level is achieved when driven off resonance.     

Elastic, piezoelectric, and dielectric characterization of modified BiScO3-PbTiO3 ceramics

The perovskite solid solution system (1-x)BiScO3-(x)PbTiO3 represents an interesting new family of high-temperature piezoelectric materials. Compositions near the morphotropic phase boundary (x approximately 0.64) have been reported to have high Curie temperatures (Tc > 450 degrees C) and good piezoelectric coefficients (d33 approximately 460 pC/N). In this work, manganese additions were used to improve the high-temperature electrical resistivity and RC time constant of compositions near the morphotropic phase boundary. The addition of manganese was found to shift Tc to slightly lower temperatures (442 degrees C and 456 degrees C for x = 0.64 and x = 0.66, respectively). The piezoelectric activities of the modified materials were found to be reduced slightly due to the hardening effect of manganese; however, the temperature stability and resistivity of the modified materials were significantly enhanced. In this paper we present, for the first time, a complete set of materials constants, including the elastic (sij, cij), piezoelectric (dij, eij, gij, hij), dielectric (epsilonij, betaij), and electromechanical (kij) coefficients and compare them to both unmodified 0.36BiScO3-0.64PbTiO3 and PZT5A ceramics.     

Precipitation phenomena in and electrical resistivity of high-temperature treated langatate (La3Ta0.5Ga5.5O14)

La(3)Ta(0.5)Ga(5.5)O(14) (LTG) single crystals, which have no phase transition up to the melting point, were heat-treated in air at temperatures from 1000°C to 1450°C for 10 h. LaTaO(4) (LT) and LaGaO(3) (LG), which coexist with LTG in the three-phase region on the Ga-poor side, precipitated on the surface of the crystal for heat treatments above 1300°C because of Ga evaporation during the heat treatment. The Ga-poor state near the surface of the 1450°C heat-treated specimen was confirmed by electron probe micro-analysis measurements. The electrical resistivity of LTG single crystals decreased by heat treatment in the range of 1000°C to 1200°C for 10 h in air, where no precipitation was observed, whereas the resistivity increased with heat treatment over 1400°C for 10 h in air. The electrical resistivity of the Ga-poor surface region was higher than that of the interior.     

Face shear piezoelectric properties of relaxor-PbTiO(3) single crystals

Poling relaxor-PbTiO(3) single crystals along pseudocubic [011] results in a macroscopic symmetry of mm2, enabling a large face shear d(36) in Zt±45° cut crystals. In order to allow the determination of electrical properties by the resonance method, square samples are required. Using Pb(In(0.5)Nb(0.5))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) crystals, piezoelectric d(36) coefficients were determined to be in the range of 2000-2500 pC∕N, with electromechanical coupling factor k(36)～0.80-0.83. Mechanical quality factor Q～180 and ultralow frequency constant of ～500 Hz m were obtained. Together with the wide temperature usage range (up to ～110 °C) and high ac driving field stability (～5 kV∕cm), such face shear crystals have a promising potential for ultralow-frequency-transducer applications.     

Relaxor-PT single crystals: observations and developments

Relaxor-PT based ferroelectric single crystals Pb(Zn?/?)Nb(?/?)O?-PbTiO? (PZNT) and Pb(Mg?/?)Nb(?/?)O?-PbTiO? (PMNT) offer high performance with ultra-high electromechanical coupling factors k?? > 0.9 and piezoelectric coefficients d??s > 1500 pC/N. However, the usage temperature range of these perovskite single crystals is limited by T(RT)-the rhombohedral to tetragonal phase transition temperature, which occurs at significantly lower temperatures than the Curie temperature T(C), a consequence of curved morphotropic phase boundaries (MPBs). Furthermore, these <001>-oriented crystals exhibit low mechanical quality Q and coercive fields, restricting their usage in high-power applications. In this survey, recent developments on binary and ternary perovskite relaxor-PT crystal systems are reviewed with respect to their temperature usage range. General trends of dielectric and piezoelectric properties of relaxor-PT crystal systems are discussed in relation to their respective T(C)/T(RT). In addition, two approaches have been implemented to improve mechanical Q, including acceptor dopants, analogous to hard polycrystalline ceramics, and anisotropic domain engineering, enabling low-loss crystals with high coupling for high-power applications.     

Electric-field-induced strain and piezoelectric properties of a high Curie temperature Pb(In1/2Nb1/2)O3-PbTiO3 single crystal

The temperature dependence of dielectric and piezoelectric properties, electric-field-induced strains of 0.66 Pb(In_1/2Nb_1/2)O₃-0.34 PbTiO₃ single crystals, which were grown directly from melt by using the modified Bridgman technique with the allomeric Pb(Mg_2/3Nb_1/3)O₃-PbTiO₃ seed crystals, were determined as a function of crystallographic orientation with respect to the prototypic (cubic) axes. Ultrahigh piezoelectric response (d₃₃∼2000 pC/N, k₃₃∼94%) and strain levels up to 0.8%, comparable to rhombohedral (1−x)Pb(Mg_2/3Nb_1/3)O₃-xPbTiO₃ and (1−x)Pb(Zn_2/3Nb_1/3)O₃-xPbTiO₃ single crystals, were observed for the 〈0 0 1〉-oriented crystals. Strain levels up to 0.47% and piezoelectric constant d₃₃∼1600 pC/N could be achieved being related to an electric-field-induced rhombohedral-orthorhombic phase transition for the 〈1 1 0〉-oriented crystals. In addition, high electromechanical coefficients k₃₃ (∼88%) can be achieved even heating to 110 °C. High T_C (∼200 °C), large electromechanical coefficients k₃₃ (∼94%) and low dielectric loss factor (∼1%), along with large strain make the crystals promising candidates for a wide range of electromechanical transducers.     

BaZrO3掺杂对(K0.49Na0.51)0.98Li0.02(Nb0.77Ta0.18Sb0.05)O3无铅压电陶瓷的结构与电性能的影响

采用固相反应法制备了(K_0.49Na_0.51)_0.98Li_0.02(Nb_0.77Ta_0.18Sb_0.05)O₃-xBaZrO₃ (NKNLST-xBZ, x = 0~0.020 mol)无铅压电陶瓷, 系统研究了BaZrO₃的掺杂量对陶瓷的压电、介电、机电和铁电性能的影响。结果表明: 随着BaZrO₃掺杂量x的增加, 陶瓷的晶体结构由正交相向四方相转变, 在x=0.005~0.008区间出现正交相与四方相两相共存的区域, 在此区域内陶瓷的晶粒变得细小且均匀, 介电损耗tanδ大幅降低, 压电常数d₃₃和平面机电耦合系数k_p增加。该体系陶瓷的介电常数ε T 33 /ε0则随着BaZrO₃的增加持续增加, 相变温度则向低温方向移动。当x=0.005时, 该组成陶瓷具有最佳的综合性能: 压电常数d33=372 pC/N, 平面机电耦合系数kp=47.2%, 介电损耗tanδ=3.1%, 以及较高的介电常数ε^T₃₃ /ε₀=1470和居里温度T_c=208℃。     

Complete set of material properties of [011](c) poled 0.24Pb(In(1/2)Nb(1/2))O(3)-0.46Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) single crystal

A complete set of elastic, piezoelectric, and dielectric constants of [011](c) poled multidomain 0.24Pb(In(1/2)Nb(1/2))O(3)-0.46Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) ternary single crystal has been determined using resonance and ultrasonic methods and the temperature dependence of the dielectric permittivity has been measured at 3 different frequencies. The experimental results revealed that this [011](c) poled ternary single crystal has very large transverse piezoelectric coefficient d(32) = -1693 pC/N, transverse dielectric constant ε(11)/ε(0) ~ 7400 and a high electromechanical coupling factor k(32) ~ 90%. In addition, its coercive field is 2 times of that of the corresponding binary 0.7Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) single system with much better temperature stability. Therefore, the crystal is an excellent candidate for transverse mode electromechanical devices.     

Structures and electrical properties of (Na0.5K0.5)NbO3–Li(Ta0.5Nb0.5)O3 lead-free piezoelectric ceramics

Solid solutions of (Na_0.5K_0.5)NbO₃ (NKN) and Li(Ta_0.5Nb_0.5)O₃ (LTN) were investigated as a potential candidate of lead-free piezoelectric ceramics. It was found that the Curie temperature of solid solutions increases slightly with increasing the LTN content and simultaneously the polymorphic phase transition temperature linearly decrease till below room temperature. An orthorhombic to tetragonal phase transformation at room temperature, or a morphotropic phase boundary, in NKN is induced by ~7 at% LTN addition, where the best dielectric, piezoelectric and electromechanical properties are achieved. The 0.94NKN–0.07LTN ceramics possess a dielectric constant of 765, a loss tangent of 0.04 at 1 kHz, a piezoelectric constant d₃₃ of 253 pC/N and an electromechanical coupling factor k_p of 48%.     

Dielectric and piezoelectric properties of CeO2-added nonstoichiometric (Na0.5K0.5)0.97(Nb0.96Sb0.04)O3 ceramics for piezoelectric energy harvesting device applications

In this study, nonstoichiometric (Na(0.5)K(0.5))(0.97)(Nb(0.96)Sb(0.04))O(3) ceramics were fabricated and their dielectric and piezoelectric properties were investigated according to the CeO(2) addition. In this ceramic composition, CeO(2) addition improved sinterability, electromechanical coupling factor k(p), mechanical quality factor Q(m), piezoelectric constant d(33), and g(33). At the sintering temperature of 1100°C, for the 0.2wt% CeO(2) added specimen, the optimum values of density = 4.359 g/cm(3), k(p) = 0.443, Q(m) = 588, ε(r) = 444, d(33) = 159 pC/N, and g(33) = 35 × 10(-3) V·m/N, were obtained. A piezoelectric energy harvesting device using 0.2 wt% CeO(2)- added lead-free (K(0.5)Na(0.5))(0.97)(Nb(0.96)Sb(0.04))O(3) ceramics and a rectifying circuit for energy harvesting were fabricated and their electrical characteristics were investigated. Under an external vibration acceleration of 0.7 g, when the mass, the frequency of vibration generator, and matching load resistance were 2.4 g, 70 Hz, and 721 Ω, respectively, output voltage and power of piezoelectric harvesting device indicated the optimum values of 24.6 mV(rms) and 0.839 μW, respectively-suitable for application as the electric power source of a ubiquitous sensor network (USN) sensor node.     

A double-mode piezoelectric single-crystal ultrasonic micro-actuator

Ternary Pb(In(1/2)Nb(1/2))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) single crystals with higher coercive field (E(C) ~9 kV/cm) and higher ferroelectric-transition temperature (T(R-T) = 108°C) were grown, and correspondingly, a double-mode piezoelectric ultrasonic micro-actuator made of PIN-PMN-PT crystal brick (5 x 1.5 x 1.32 mm) and operated in the first longitudinal and the second bending modes was developed. The ferroelectric, dielectric, electromechanical, and resonance displacement properties of the micro-actuator were characterized for miniature linear piezo-motor applications. The longitudinal displacement of the actuator is ~0.11 μm (with an applied voltage of 5 V), which is comparable to that of a multilayer piezoelectric-ceramic actuator of the same size. This crystal micro-actuator was successfully used to drive a slider moving linearly.     

Measurements along the growth direction of PMN-PT crystals: dielectric, piezoelectric, and elastic properties

Property measurements are reported for Pb(Mg1/3Nb2/3)03-PbTiO3 (PMN-PT) single crystals grown along (001) by a seeded-melt method. Chemical segregation occurs during crystal growth, leading to property changes along the growth direction. Variations in dielectric, piezoelectric, and elastic properties were evaluated for specimens selected from the crystals. Room-temperature data are correlated with Tc and composition that ranged from 27 to 32% PT, i.e., in the vicinity of the morphotropic phase boundary (MPB). While there was little change in the high electromechanical coupling factor k33 (0.87-0.92), both the piezoelectric charge coefficient d33 (1100-1800 pC/N) and the free dielectric constant K3 (4400-7000) were found to vary significantly with position. Increases in d33 and KT33 were relatively offsetting in that the ratio yielded a relatively stable piezoelectric voltage coefficient g33 (27-31 x 10(-3) Vm/N). Values are also reported for the elastic compliance (3.3-6.3 x 10(-11) m2/N) determined from resonance measurements. Enhancements in d33 and K(T)33 were associated with lattice softening (increasing sE33) as the composition approached the MPB. Details are reported for the piezoelectric, dielectric, and elastic properties as a function of growth direction, Tc, and composition. The results are useful for an understanding of properties in PMN-PT crystals and for the design of piezoelectric devices.     

Phase separation during the melting of oxide borates LnCa4O(BO3)3 (Ln=Y, Gd)

GdCa₄O(BO₃)₃ (GdCOB) and YCa₄O(BO₃)₃ (YCOB) single crystals have been grown from the melt by the Czochralski method. Subsequent DTA analysis of the single crystals showed different behavior for both substances. During the first heating both crystals showed a single sharp melting peak at 1490°C (GdCOB) or at 1504°C (YCOB), respectively. In subsequent heating/cooling runs only GdCOB shows one single peak, whereas YCOB shows five peaks. Moreover, phase separation of the melt can be observed by optical observation and by EDX measurements. This behavior can be explained by a miscibility gap in the YCOB melt. The YCOB crystal is formed from the stoichiometric melt by a monotectic reaction.     

铌镁酸铋-钛酸铅压电陶瓷准同型相界附近的性能和相变温度研究

利用传统固相烧结法制备了Bi(Mg_2/3Nb_1/3)O₃-PbTiO₃(BMN-PT)压电陶瓷, 分析了不同PbTiO₃含量对BMN-PT压电陶瓷的晶体结构、介电、压电及铁电性能的影响. XRD结果表明: 合成的BMN-PT陶瓷具有纯钙钛矿结构, 并且在PbTiO₃含量为x=0.60时, 其组分的XRD图谱在衍射角2θ=45°出现明显的分峰, 说明该组分相结构中存在三方和四方相的共存. 压电铁电性能显示, BMN-0.60PT有最大的压电常数d₃₃(~170pC/N)和平面机电耦合系数k_p(0.35), 最小的矫顽场E_c(29.4 kV/cm)及最大的剩余极化P_r(31.4 μC/cm²). 确定了BMN-PT压电陶瓷的准同型相界(MPB)为PbTiO₃含量x=0.60的组分. 介电系数温谱表明介电系数峰值温度(Tm)随着PbTiO₃含量的增大而升高, MPB组分的Tm约为276℃.     

Temperature behavior of dielectric and piezoelectric properties of samarium-doped lead titanate ceramics

The dielectric and electromechanical coupling properties of Sm-doped and Mn-doped PbTiO(3) ceramics were investigated from 4.2 to 300 K. The upper and lower limits of the ceramic dielectric and piezoelectric properties were calculated by averaging the single-domain constants that were determined from a phenomenological theory. Comparisons of the measured and calculated properties were then made. The measured dielectric permittivity epsilon(T)(33) and piezoelectric strain coefficient d(33) appear to be mainly due to the averaging of the intrinsic single-domain response. The large piezoelectric and electromechanical anisotropies present in modified PbTiO(3) ceramics also appear to be an intrinsic property of the material. The piezoelectric coefficient d(31), as well as the planar coupling coefficient k(p), was found to have very small values over two temperature regions, from 120 to 170 K and from 240 to 270 K.     

Thermal hysteresis of electromechanical characteristics of <Emphasis Type="Italic">Y</Emphasis> + 42° cut LiTaO<Subscript>3</Subscript> single crystals

The temperature stability of electromechanical characteristics of Y + 42° cut LiTaO₃ crystals has been studied using dielectric spectroscopy and static and dynamic piezoelectric effect measurements. It has been shown that, during thermal cycling, the piezoelectric properties of crystalline LiTaO₃ samples exhibit a thermal hysteresis and that the thermal history of samples influences their resonance and antiresonance frequencies.     

Characteristics of relaxor-based piezoelectric single crystals forultrasonic transducers

For ultrasonic transducers, piezoelectric ceramics offer a range of dielectric constants (K~1000-5000), large piezoelectric coefficients (d_ij~200-700 pC/N), and high electromechanical coupling (k _t≃50%, k₃₃≃75%). For several decades, the material of choice has been polycrystalline ceramics based on the solid solution Pb(Zr_1-xB_2x)O₃ (PZT), compositionally engineered near the morphotropic phase boundary (MPB). The search for alternative MPB systems has led researchers to revisit relaxor-based materials with the general formula, Pb(B₁,B₂)O₃ (B₁:Zn²⁺ , Mg²⁺, Sc³⁺, Ni²⁺..., B₂ :Nb⁵⁺ Ta⁵⁺...). There are some claims of superior dielectric and piezoelectric performance compared to that of PZT materials. However, when the properties are examined relative to transition temperature (T₃), these differences are not significant. In the single crystal form, however, Relaxor-PT materials, represented by Pb(Zn_1/3Nb_2/3)O₃-PbTiO ₃ (PZN-PT), Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) have been found to exhibit longitudinal coupling coefficients (k₃₃)>90%, thickness coupling (k_t)>83%, dielectric constants ranging from 1000 to 5000 with low dielectric loss <1%, and exceptional piezoelectric coefficients d₃₃>2000 pC/N, the later promising for high energy density actuators. For single crystal piezoelectrics to become the next generation material of ultrasonic transducers, further investigation in crystal growth, device fabrication and testing are required