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.     

Electromechanical properties of fine-grain, 0.7 Pb(Mg(1/3)Nb(2/3))O3-0.3PbTiO3 ceramics

A fine grain, relaxor-based piezoelectric ceramic 0.7 Pb(Mg(1/3)Nb(2/3))O3-0.3PbTiO3 (PMN-30% PT) has been investigated, which was fabricated using the columbite precursor method. The complete set of electromechanical properties of the piezoceramic at room temperature is determined using a combination of ultrasonic and resonance techniques. This fine-grain ceramic (grain size < or = 2.5 microm) exhibits ultra-high dielectric permittivity (epsilon33(T)/epsilon0 approximately 7000) and a high coupling coefficient k(33) (= 0.78). Ultrasonic spectroscopy was used to measure the dispersion of the phase velocity and attenuation for the longitudinal wave propagating in the poling direction. Lower attenuation and smaller velocity dispersion were observed compared to modified Pb(Zr(x)Ti(1-x)O3 (PZT-5H) ceramics. The measurement results show that this fine-grain PMN-30% PT ceramic is a very good material for making ultrasonic array transducers.     

Anisotropy in domain engineered 0.92Pb(Zn1/3 Nb2/3)O3-0.08PbTiO3 single crystal and analysis of its property fluctuations

The orientation dependence of slowness and electromechanical coupling coefficients of 0.92Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-0.08PbTiO/sub 3/ (PZN-8%PT) domain engineered single crystal was analyzed based on the measured complete set of elastic, piezoelectric, and dielectric constants. There exist one quasi-longitudinal, one quasi-shear, and one pure shear wave in each of the [100]-[010], [010]-[001], and [001]-[110] planes. The slowness of the quasi-shear wave exhibits strong anisotropy in all three planes, and the coupling coefficient k/sub 33/ and k/sub 31/ reach their maximum in [001] and [110] directions of cubic axis, respectively. Because the composition of the PMN-8%PT system is very close to the morphotropic phase boundary, the extraordinary large piezoelectric coefficients d/sub 31/ and d/sub 33/, and high coupling coefficient k/sub 33/ are very sensitive to compositional variation. We have performed error analysis and proposed an improved characterization scheme to derive a complete data set with best consistency.     

Piezoelectric composites with high sensitivity and high capacitance for use at high pressures

A type of piezoelectric composite has been developed for oceanographic applications. The composites have a large figure of merit (d(h)xg(h) or d(h )xg(h)/tan delta, where d(h ) is the hydrostatic piezoelectric voltage coefficient), a large dielectric constant (K) and low dielectric loss, and great mechanical strength. A shallow cavity between the PZT ceramics and thick metallic electrode is designed to convert a portion of the z-direction stress into a large radial and tangential stress of opposite sign. thereby causing the d(33) and d(31) contributions to d(h) to add rather than subtract, and raising the figure of merit. Theoretical stress analysis was carried out using an axisymmetric finite element method. Experimental results show that the d(h)x g(h), K, and withstandable pressure are extremely high.     

Piezoelectric ceramics with high dielectric constants for ultrasonic medical transducers

Complex system ceramics Pb(Sc(1/2)Nb(1/2))O3-Pb(Mg(1/3)Nb(2/3))O3-Pb(Ni(1/2)Nb(1/2))O3-(Pb0.965,Sr0.035) (Zr,Ti)O3 (PSN-PMN-PNN-PSZT abbreviated PSMNZT) have been synthesized by the conventional technique, and dielectric and piezoelectric properties of the ceramics have been investigated for ultrasonic medical transducers. High capacitances of the transducers are desired in order to match the electrical impedance between the transducers and the coaxial cable in array probes. Although piezoelectric ceramics that have high dielectric constants (epsilon33t/epsilon0 > 5000, k'33 < 70%) are produced in many foundries, the dielectric constants are insufficient. However, we have reported that low molecular mass B-site ions in the lead-perovskite structures are important in realizing better dielectric and piezoelectric properties. We focused on the complex system ceramics PSMNZT that consists of light B-site elements. The maximum dielectric constant, epsilon33T/epsilon0 = 7, 200, was confirmed in the ceramics, where k'33 = 69%, d33 = 940 pC/N, and T(c) = 135 degrees C were obtained. Moreover, pulse-echo characteristics were simulated using the Mason model. The PSMNZT ceramic probe showed echo amplitude about 5.5 dB higher than that of the conventional PZT ceramic probe (PZT-5H type). In this paper, the electrical properties of the PSMNZT ceramics and the simulation results for pulse-echo characteristics of the phased-array probes are introduced.     

PZT陶瓷/橡胶复合材料的压电性能

用PZT压电陶瓷粉末分散在无压电性的橡胶基体中制成压电复合材料。通过压电常数和介电常数测定、扫描电镜、介电谱等手段研究了有关因素对复合材料压电性能的影响。结果表明,复合材料的压电常数d₃₃随PZT体积含量φ和橡胶介电常数ε₁的增加而增大,随PZT介电常数ε₂的增加而减小,符合理论式 d₃₃=15φε₁d₃₃/(1-φ)(2+3φ)ε₂ 橡胶基体的极性基团、极性链节和交联健偶极的转向极化及分子链的柔性对复合材料的极化和压电常数有重要影响。橡胶的极性越大及分子链的柔性越高,则复合材料的压电常数d₃₃越高。      

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.     

1-3型水泥基压电复合材料的制备及性能

采用切割-浇注法, 以硫铝酸盐水泥为基体, 制备了1-3型水泥基压电复合材料。详细阐述了1-3型水泥基压电复合材料的制备过程; 研究了0.375Pb(Mg_1/3Nb_2/3)O₃-0.375PbTiO₃-0.25PbZrO₃压电陶瓷柱的宽厚比w/t对1-3型水泥基压电复合材料的压电性能、 介电性能和声阻抗的影响。结果表明: 压电陶瓷柱的宽厚比w/t对1-3型水泥基压电复合材料性能有很大影响, 随着w/t的增加, 其压电应变常数d₃₃、 机电耦合系数K_p与K_t、 机械品质因数Q_m、 介电常数ε_r和介电损耗tanδ均随着w/t的增加而减小, 而压电电压常数g₃₃值几乎不受w/t的影响。在压电陶瓷体积分数仅为22.72%的条件下, 调节压电陶瓷柱的宽厚比w/t至0.130, 可使复合材料的声阻抗与混凝土的声阻抗十分接近, 从而有效地解决了智能材料在土木工程中的声阻抗相容性问题。      

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℃.     

Piezoelectric properties of (K,Na)NbO3 thin films deposited on (001)SrRuO3/Pt/MgO substrates

(K(x),Na(1-x))NbO(3) (KNN) thin films were deposited on (001)SrRuO(3)/(001)Pt/(001)MgO substrates by RF-magnetron sputtering, and their piezoelectric properties were investigated. The x-ray diffraction measurements indicated that the KNN thin films were epitaxially grown with the c-axis orientation in the perovskite tetragonal system. The lattice constant of the c-axis increased with increasing concentrations of potassium. The KNN thin films showed typical ferroelectric behavior; the relative dielectric constant epsilon(r) was 270 to approximately 320. The piezoelectric properties were measured from the tip displacement of the KNN/MgO unimorph cantilevers; the transverse piezoelectric coefficient epsilon*(31) (= d(31)/s(E)(11)) of KNN (x = 0) thin films was calculated to be -0.9 C/m(2). On the other hand, doping of potassium caused an increase in the piezoelectric properties, and the KNN (x = 0.16) films showed a relatively large transverse piezoelectricity of epsilon*(31) = -2.4 C/m(2).     

Dielectric and electromechanical properties of barium titanate single crystals grown by templated grain growth

Single crystals of BaTiO(3) were grown by templated grain growth (TGG). TGG involves contacting a single crystal "template" to a sintered polycrystalline matrix, then heating the assemblage to a temperature that promotes the migration of the single crystal boundary through the matrix. In this investigation the properties of millimeter-sized, plate-shaped and bar-shaped, single crystals of BaTiO(3) grown by TGG were examined in order to compare the results to single crystals grown by conventional methods. A dielectric constant, epsilon(33)(T)/epsilon(0), of 260, polarizations of P(R)~16 muC/cm(2) and P(sat)~21.5 muC/cm(2), electromechanical coupling coefficients of k(33)~0.51 and k(31)~0.18, and a piezoelectric coefficient of d(33)~140 pC/N were achieved. Entrapped porosity in the crystals made fully poling the crystals difficult.     

Elastic, piezoelectric, and dielectric properties of 0.955Pb(Zn(1/3)Nb(2/3))O(3)-0.45PbTiO(3 ) single crystal with designed multidomains

The elastic, piezoelectric, and dielectric properties of a 0.955Pb(Zn(1/3)Nb(2/3))O(3)-0.045PbTiO(3 ) (PZN-4.5%PT) multi-domain single crystal, poled along [001] of the original cubic direction, have been determined experimentally using combined resonance and ultrasonic methods. At room temperature, the PZN-4.5%PT single crystal has rhombohedral symmetry. After being poled along [001], four degenerate states still remain. Statistically, such a domain-engineered crystal may be treated as having an average tetragonal symmetry, and its material constants were determined based on 4 mm symmetry. It was confirmed that the electromechanical coupling coefficient k(33) for the domain-engineered samples is >90%, and the piezoelectric constant d(33) is >2000 pC/N. A soft shear mode with a velocity of 700 m/s was found in the [110] direction. From the measured experimental data, the orientational dependence of phase velocities and electromechanical coupling coefficients was calculated. The results showed that the transverse and longitudinal coupling coefficients, k(31) and k(33), reach their maximum along [110] and [001], respectively.     

Determination of mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal

Mass density, dielectric, elastic, and piezoelectric constants of bulk GaN crystal were determined. Mass density was obtained from the measured ratio of mass to volume of a cuboid. The dielectric constants were determined from the measured capacitances of an interdigital transducer (IDT) deposited on a Z-cut plate and from a parallel plate capacitor fabricated from this plate. The elastic and piezoelectric constants were determined by comparing the measured and calculated SAW velocities and electromechanical coupling coefficients on the Z- and X-cut plates. The following new constants were obtained: mass density p = 5986 kg/m(3); relative dielectric constants (at constant strain S) ε(S)(11)/ε(0) = 8.6 and ε(S)(11)/ε(0) = 10.5, where ε(0) is a dielectric constant of free space; elastic constants (at constant electric field E) C(E)(11) = 349.7, C(E)(12) = 128.1, C(E)(13) = 129.4, C(E)(33) = 430.3, and C(E)(44) = 96.5 GPa; and piezoelectric constants e(33) = 0.84, e(31) = -0.47, and e(15) = -0.41 C/m(2).     

Electromechanical properties and anisotropy of single- and multi-domain 0.72Pb(Mg(1∕3)Nb(2∕3))O(3)-0.28PbTiO(3) single crystals

Complete sets of elastic, piezoelectric, and dielectric constants of 0.72Pb(Mg(1∕3)Nb(2∕3))O(3)-0.28PbTiO(3) single crystal poled along [111](c) (single domain) as well as non-polar axes [001](c) and [011](c) (multidomain) have been measured under natural conditions. These data allowed us to evaluate accurately the extrinsic contributions to the superior piezoelectric properties. Very large extrinsic contributions to the unusual anisotropies in multidomain crystals are confirmed. We found that the instability of domain structures is the origin of the low mechanical quality factor Q for the multidomain relaxor-based ferroelectric single crystals. Our results can provide useful guidance in future design of domain engineered materials.     

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.     

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.     

PMN-PT nanowires with a very high piezoelectric constant

A profound way to increase the output voltage (or power) of the piezoelectric nanogenerators is to utilize a material with higher piezoelectric constants. Here we report the synthesis of novel piezoelectric 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-PT) nanowires using a hydrothermal process. The unpoled single-crystal PMN-PT nanowires show a piezoelectric constant (d(33)) up to 381 pm/V, with an average value of 373 ± 5 pm/V. This is about 15 times higher than the maximum reported value of 1-D ZnO nanostructures and 3 times higher than the largest reported value of 1-D PZT nanostructures. These PMN-PT nanostructures are of good potential being used as the fundamental building block for higher power nanogenerators, high sensitivity nanosensors, and large strain nanoactuators.     

Preparation of (001)-oriented Pb(Zr,Ti)O3 thin films and their piezoelectric applications

Preparation of (001)-oriented Pb(Zr,Ti)O(3) (PZT) thin films and their applications to a sensor and actuators were investigated. These thin films, which have a composition close to the morphotropic phase boundary, were epitaxially grown on (100)MgO single-crystal substrates by RF magnetron sputtering. These (001)-oriented PZT thin films could be obtained on various kinds of substrates, such as glass and Si, by introducing (100)-oriented MgO buffer layers. In addition, the (001) oriented PZT thin films could be obtained on Si substrates without buffer layers by optimizing the sputtering conditions. All of these thin films showed excellent piezoelectric properties without the need for poling treatment. The PZT thin films on the MgO substrates had a high piezoelectric coefficient, d(31), of -100 pm/V, and an extremely low relative dielectric constant, epsilon(r), of 240. The PZT thin films on Si substrate had a very high d(31) of -150 pm/V and an epsilon(r) = 700. These PZT thin films were applied to an angular rate sensor with a tuning fork in a car navigation system, to a dual-stage actuator for positioning the magnetic head of a high-density hard disk drive, and to an actuator for an inkjet printer head for industrial on-demand printers.     

成型压力对0-3型锆钛酸铅/水泥压电复合材料的影响

以快硬硫铝酸盐水泥为基体,以锆钛酸铅(PZT)为功能相,用压制成型法制备出0-3型PZT/水泥基压电复合材料。分析成型压力对PZT/水泥基压电复合材料的压电性和介电性的影响,结果表明:不同粒径PZT颗粒作为功能相的水泥基压电复合材料,成型压力对其压电性和介电性有不同的影响。在30~90 MPa压力范围内,成型压力越大,PZT/水泥压电复合材料的压电应变常数d33和相对介电常数εr均显著提高,这是由于气孔率随压力增大而减少,而压电电压常数g33的变化则与功能相的粒径有关。机电耦合系数也有着不同的变化趋势,对于6μm和126μm PZT/水泥压电复合材料,其机电耦合系数Kt和Kp随压力增大缓慢下降,而对于430μm PZT/水泥压电复合材料则呈上升趋势。当压力达到150 MPa时,其压电性和介电性均急剧减小。     

PZT基陶瓷铁电－反铁电相界处各向异性的研究

本文研究了两个以ＰＺＴ瓷为基的系统：ＰＺＴ（Ｎｂ）和ＰＳＺＴ陶瓷在铁电－反铁电相界区域的压电和机电耦合等性能．结果表明，ＰＺＴ基陶瓷在该相界处具有高Ｋｔ和低Ｋｐ的性质．压电和机电耦合各向异性也比准同型相界要高，｜ｄ３３／ｄ３１｜＞５．５，Ｋｔ／Ｋｐ＞３．０．借助于电场诱导ＡＦ—Ｆ相变和反铁电双子晶格间的强耦合作用，对此现象作了较好解释．