Piezoelectric Strain Constant Research Articles

Crystal Growth and Electric-Field-Induced Strain in Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub> Crystals

Large Bi0.5Na0.5TiO3 (BNT) single crystals with 10 mm × 10 mm × 5 mm were successfully grown by a flux method using BNT powder and the mixed flux composed of Bi2O3 and NaF. Dielectric measurements show a dielectric-permittivity peak at 310°C, which is the result of the gradual phase transition from rhombohedral (R3c) to tetragonal (P4bm) structure. Electric-field induced strain measurements along [100]C reveal that the effective piezoelectric strain constant (d33 *) was estimated to be 130 pm/V in a multidomain state.

Crystal growth and dielectric, piezoelectric and elastic properties of Ca 3NbGa 3Si 2O 14 single crystal

Single crystals of Ca 3NbGa 3Si 2O 14 (CNGS) were successfully grown from stoichiometric melts by conventional Czochralski technique along the a-axis and two large (0 0 0 1) facets and two small (0 1 1¯ 0) facets appear in every crystal. High-resolution X-ray diffraction (HRXRD) results indicate that CNGS crystals have good quality and are free of low-angle boundaries. The relative dielectric constants, the piezoelectric strain constants and elastic compliance constants of CNGS single crystal, have been determined by an electrical bridge and resonant–antiresonant method. The two piezoelectric strain constants, d 11 and d 14, are 4.40×10 −12 coulomb per newton (C/N) and −10.44×10 −12 C/N, respectively. The elastic compliance constants were measured and elastic stiffness constants were calculated from piezoelectric equations.

Sintering and Electrical Properties of Lead‐Free Na0.5K0.5NbO3 Piezoelectric Ceramics

Lead‐free Na0.5K0.5NbO3 (NKN) piezoelectric ceramics were fairly well densified at a relatively low temperature under atmospheric conditions. A relative density of 96%–99% can be achieved by either using high‐energy attrition milling or adding 1 mol% oxide additives. It is suggested that ultra‐fine starting powders by active milling or oxygen vacancies and even liquid phases from B‐site oxide additives mainly lead to improved sintering. Not only were dielectric properties influenced by oxide additives, such as the Curie temperature (Tc) and dielectric loss (D), but also the ferroelectricity was modified. A relatively large remanent polarization was produced, ranging from 16 μC/cm2 for pure NKN to 23 μC/cm2 for ZnO‐added NKN samples. The following dielectric and piezoelectric properties were obtained: relative permittivity ɛT33/ɛ0=570–650, planar mode electromechanical coupling factor, kp=32%–44%, and piezoelectric strain constant, d33=92–117 pC/N.

Realization of high-energy density polycrystalline piezoelectric ceramics

This letter reports a high energy density piezoelectric material in the system given as: Pb[(Zr0.52Ti0.48)O3]1−x[(Zn1∕3Nb2∕3)O3]x+yMnCO3, where x=0.1 and y varies from 0.5to0.9wt%. A piezoelectric material with high energy density is characterized by a high product of piezoelectric voltage constant (g) and piezoelectric strain constant (d). The condition for obtaining large magnitude of g constant was derived to be as ∣d∣=εn, where ε is the permittivity of the material and n is constant having lower bound of 0.5. It was found that for all practical polycrystalline piezoelectric ceramic materials the magnitude of n lies in the range of 1.1–1.30 and as the magnitude of n decreases towards unity a giant enhancement in the magnitude of g was obtained. A two step sintering process was developed to optimize a polycrystalline ceramic composition with low magnitude of n. For the optimized composition the value of g33 and d33 was found to be 55.56×10−3m2∕C and 291×10−12C∕N, respectively, yielding the magnitude product d33∙g33 as ∼16168×10−15m2∕N which is significantly higher than the reported values in literature. The magnitude of n for this composition was calculated to be 1.151. This material is extremely promising for immediate applications in the sensing and energy harvesting.

( La 0.8 , Sr 0.2 ) MnO 3 ∕ Ti -metal foil substrate heterostructure effects on the ferroelectric and piezoelectric properties of lead zirconate titanate thin films

The ferroelectric and piezoelectric properties of lead zirconate titanate thin films deposited on a (La0.8,Sr0.2)MnO3(LSMO)∕Ti-metal foil heterostructure are reported. The results are compared to those of films of similar thickness deposited on platinized silicon substrate. It is shown that the films deposited on LSMO∕Ti are characterized by square ferroelectric and piezoelectric hysteresis loops with high remnant polarization and strain of 26μC∕cm2 and 0.8%, respectively. The effective piezoelectric strain constant, d33, obtained for films deposited on platinized silicon amounts to 103pm∕V. The piezoelectric behavior of the film deposited on LSMO∕Ti is analyzed in terms of a unimorph bending actuator. The extracted effective piezoelectric strain constant, d33, amounts to approximately 600pm∕V.

Piezoelectric and magnetic properties of PZT-(Ni0.284Zn0.549Cu0.183)Fe1.984O4 composites

The piezoelectric/piezomagnetic composite, PZT/Ni0.284Zn0.549Cu0.183Fe1.984O4, was fabricated by the mixed oxide method. The phase assemblage, piezoelectric strain constant and saturation magnetization were investigated. The results indicate that the PZT phase is compatible with Ni0.284Zn0.549Cu0.183Fe1.984O4 phase, and dense diphasic ceramic composites were obtained. It is found that piezoelectric strain constant decreases exponentially as the amount of doped piezomagnetic materials in the composite increases. Correspondingly, saturation magnetization of the composite also decreases with the increasing weight fraction of piezoelectric materials. Three reasons cause the results. First, the grain growth of piezomagnetic phase at the co-sintering temperature reduces grain size and continuity of the piezoelectric phase. Second, the pore size and porosity in composite increase dramatically with increasing amount of piezomagnetic phase. Third, the low resistivity of the composite prevents the poling process and reduces the piezoelectric strain constant. The tailoring of microstructure to achieve a high performance piezoelectric/piezomagnetic composite is proposed based on the analysis.

Microstructure and piezoelectric properties of sub-80 nm high polycrystalline SrBi2Ta2O9 nanostructures within well-ordered arrays

Well-ordered arrays of sub-80 nm high SrBi2Ta2O9 nanostructures were fabricated on SrTiO3:Nb (111) single-crystal substrates by latex sphere lithography. The as-prepared nanostructures have a pyramid-like shape with around 220 nm lateral dimension at half their height. After annealing, the pyramid-like shape changes due to the formation of nano-sized SrBi2Ta2O9 grains of high crystal anisotropy in the individual nanostructures. Microstructure and piezoelectric properties of the nanostructures were investigated by cross-sectional transmission electron microscopy and piezoresponse force microscopy, respectively. Scattering in piezoelectric strain constants d33 was observed, probably arising from varying orientations, high anisotropy, and interfacial diffusion layer of the polycrystalline SrBi2Ta2O9 nanostructures on SrTiO3. The d33 increases continuously with dc bias and reaches 8pm∕V at a bias of 20 V. The size effect on piezoelectric properties of SrBi2Ta2O9 was found to be much less severe than that in BaTiO3. The acquired piezoresponse hysteresis loops proved that 30 nm high SrBi2Ta2O9 nanostructures are still ferroelectric.

Design and Performance of Miniaturized Piezoelectric Step-Down Transformer

Piezoelectric transformers are expected to be small, thin and highly efficient, and which are attractive as a transformer with high power density for step down voltage. For these reasons, we have attempted to develop a step-down piezoelectric transformer for the miniaturized adaptor. we propose a piezoelectric transformer, operating in thickness extensional vibration mode for step-down voltage. This transformer consists of a multi-layered construction in the thickness direction. In order to develop the step-down piezoelectric transformers of 10 W class and turn ratio of 0.1 with high efficiency and miniaturization, the piezoelectric ceramics and piezoelectric transformer designs are estimated with a variety of characteristics. The basic composition of piezoelectric ceramics consists of ternary yPb(Zr x Ti1 − x)O3−(1−y)Pb(Mn1/3Nb1/3Sb1/3)O3. In the piezoelectric characteristics evaluations, at y = 0.95 and x = 0.505, the electromechanical coupling factor(kp) is 58%, piezoelectric strain constant (d33) is 270 pC/N, mechanical quality factor(Qm) is 1520, permittivity (e 33 T /e0) is 1500, and Curie temperature is 350∘C. At y = 0.90 and x = 0.500, kp is 56%, d33 is 250 pC/N, Qm is 1820, e33 T /e0 is 1120, and Curie temperature is 290∘C. It shows the excellent properties at morphotropic phase boundary regions. PZT-PMNS ceramic may be available for high power piezoelectric devices such as piezoelectric transformers. The design of step-down piezoelectric transformers for adaptor proposes a multi-layer structure to overcome some structural defects of conventional piezoelectric transformers. In order to design piezoelectric transformers and analyze their performances, the finite element analysis and equivalent circuit analysis method are applied. The maximum peak of gain G as a first mode for thickness extensional vibration occurs near 0.85 MHz at load resistance of 10 Ω. The peak of second mode at 1.7 MHz is 0.12 and the efficiency is 92%.

Piezoelectric and Dielectric Properties of Pb(ZrxTi1 ? x)O3-Pb(Ni1/3Sb1/3Nb1/3)O3 Piezoelectric Ceramics

In this paper, piezoelectric and dielectric properties of 0.9PbZrxTi1−xO3-0.1PbNi1/3Sb1/3Nb1/3O3 were studied as a function of Zr/Ti mole ratio(x) for application to piezoelectric actuator. Also, microstructure and crystalline phase are investigated by using SEM and XRD, respectively. As a results, the substitution of Sb5+ to B-site increases the piezoelectric and dielectric properties, and when Zr/Ti mole ratio is 49/51 and ternary mole ration is 0.1(0.9PbZr0.49Ti0.51O3-0.1PbNi1/3Sb1/3Nb1/3O3), the corresponding composition were found belonging to the Morphotropic Phase Boundary region with electromechanical coupling coefficient(kp), mechanical quality factor (Qm), permittivity(er) and piezoelectric strain constant(d33) equaled to 63%, 360, 2000 and 470 pC/N, respectively. Sintering temperature was about 1150_∘C and Curie temperature was determined around 290_∘C.

Investigation on possibility of neutron electric optical devices based on piezoelectric single crystals

A principle verification experiment of neutron electric optical devices using piezoelectric single crystals was carried out. This neutron electric optical device can change its d-spacing by applying an electric field to the crystal, which results in change of the Bragg diffraction angle. Although an α-quartz has a small piezoelectric strain constant, an α-quartz was used in this experiment because characteristics of α-quartz are well known and it is easy to obtain high quality and large size single crystals. At first, macroscopic distortion and change of thickness caused by an applied electric field were observed by using laser interferometers. Thus, double crystal diffraction measurement using 4.7 Å cold neutrons was carried out. For these experiments, DC bias voltage was applied to the crystal. As a result, peaks of rocking curves were shifted 14 s at 500 V and 2 min at 1000 V from their original positions. These values were approximately one figure larger than the theoretical values; therefore, these results were influenced by macroscopic bending of the crystal. From these results, it can be concluded that the possibility of neutron electric optical devices using not only change of d-spacing but also macroscopic bending of piezoelectric crystal was confirmed.

PZT-PMN Ceramics for Large Displacement Piezoelectric Devices

Piezoelectric and dielectric properties as functions of x and y mole ratio in yPb(ZrxTil-x)O(1-y)Pb(Mn1/3/Nb/2/3/)O, ceramics, PZT-PMN, are investigated for large displacement piezoelectric devices. From the experimental results, when y is 0.95 and x is 0.505, the piezoelectric and dielectric properties are maximum, that is, electromechanical coupling coefficient(kp), piezoelectric strain constant(d33/), permittivity(33/T//0/), and Curie temperature are 58 %, 272 pC/N, 1520 and about 350, respectively. Also, when y is 0.90 and x is 0.50, their properties are 56 %, 242 pC/N, 1220, and 290, respectively. As MgO dopant is added from 0 wt% to 1 wt%, kp increases to 63 % and Qm decreases to 500 at the MgO dopant of 0.1 wt%, and then kp decreases to 57 % as MgO is added.

Growth, properties and electrooptical applications of single crystal La3Ga5SiO14

The growth of single crystal La 3 Ga 5 SiO 14 (LGS) is briefly introduced. The transmission spectra show that the UV absorption edge is as low as 236 nm for the colorless LGS crystal sample. The dielectric constants, piezoelectric strain constants and elastic compliance constants are determined using LCR bridge, interferometric and resonance methods, respectively. The linear electrooptic coefficients γ 11 and γ 41 are measured to be 2.3 and 1.8 pm/V respectively by the interferometric method. A new kind of electrooptic Q-switch is designed by using the LGS crystal. The half-wave voltage of the Q-switch is 2250 V, and the single pulse output energy of 200 mJ is obtained with a pulse width of 9.4 ns. The damage threshold is about six times as large as that of a LiNbO 3 Q-switch under the same conditions.

Domain structures in KNbO3 crystals and their piezoelectric properties

The electromechanical coupling factor for the thickness-extensional mode, kt, in KNbO3 crystals has been predicted to be as high as 69% for the 49.5° rotated X-cut about the Y-axis, which is the highest among known piezoelectrics. This paper presents the experimental confirmation of the high coupling factor and elucidates the relationship between the domain structure and the piezoelectric properties in the pseudocubic (001)pc cut, which is close to the maximum kt cut and has a piezoelectric strain constant about 2.9 times that of the Z-cut. Etching of crystals is found to have an outstanding effect on the piezoelectric characteristics. That is, in the case of “as-cut” crystals, the strain versus electric field curves have a large hysteresis and instability due to the occurrence of 60° domains in a high electric field region, whereas etched crystals remain the single domain state and exhibit linear piezoelectric properties even in the high electric field region. It is also demonstrated that the (001)pc cut crystal poled along the 〈001〉pc direction has a polar multidomain structure composed of two kinds of 90° domains, not four kinds of equivalent domains, and that it exhibits almost the same piezoelectric properties as those of single-domain crystals.

Crystal growth and physical properties of UV nonlinear optical crystal zinc cadmium thiocyanate, ZnCd(SCN) 4

Zinc cadmium thiocyanate, ZnCd(SCN) 4 (ZCTC) single crystals of optical quality have been grown from aqueous solution by controlled evaporation at 40 °C. The morphology of the crystal was indexed. Raman spectroscopy, refractive indices, optical transmission and optical damage threshold of the ZCTC crystal were all performed at room temperature. Violet and ultraviolet (UV) light output by frequency doubling of a 808 nm GaAlAs laser diode and a continuous wave Ti:sapphire laser at 760 nm were achieved. The dielectric constants, piezoelectric strain constants, electroptic coefficients, and direct current resistivities have also been measured.

The study of piezoelectric ceramic-metal composite with single cavity

A piezoelectric ceramic-metal composite with single cavity has been developed. The composite has not only high piezoelectric strain constant, also advantages of small position-dependence, easy manufacture and high stability, which make it fixed easily. The optimum dimensions of composite have been obtained by experiment. The relative effective piezoelectric strain constant is 7890pC/N which is 24 times that of PZT piezoelectric ceramic (d 33=330pC/N).

Non Linear Behavior of the Permittivity and of the Piezoelectric Strain Constant Under High Electric Field Drive

Two methods are proposed and compared for the measurement of the converse piezoelectric strain constant: A Laser Doppler Vibrometer Technique and a Capacitance Probe. The complete results obtained with the Capacitance Probe device are given for “hard” and “soft” PZT samples between 1 Hz - 1 kHz and up to 700 Vp with and without a dc offset bias. The permittivity is also studied under various conditions of electric drive (ac, dc, ac + dc . . .) with the help of a LCR meter and a Schering Bridge. Many analogies between the dielectric non linearities and the piezoelectric one's are observed. In both cases the high field behavior follows the empirical Rayleigh law providing that the dc and ac influences would be separated.

Effects of Microstructure on the Dielectric and Piezoelectric Properties of Lead Metaniobate

In an attempt to obtain dense PbNb2O6 ceramics, sintering experiments were conducted using starting powders with various particle sizes and different modifications (rhombohedral and orthorhombic structures). During sintering of rhombohedral powders, the phase transformation to the tetragonal phase promoted grain growth, resulting in poor densification. Sintering of orthorhombic powders, however, yielded dense ceramics through suppression of the phase transformation. Based on these results, ceramics with various densities and different microstructures were prepared, and their dielectric and piezoelectric properties were evaluated. The dielectric constant and Curie temperature were dependent on density, grain size, and crack density. Cracks and intragrain pores severely deteriorated the piezoelectric properties. Dense ceramics with the maximum coupling factors and piezoelectric strain constants were obtained by prolonged heating of a fine powder with orthorhombic structure.

Preferred orientation and piezoelectricity in sputtered ZnO films

Thin ZnO films were deposited on various types of substrates with rf magnetron reactive sputtering of a Zn target in pure O2 atmosphere. The layers were characterized by x-ray diffraction and electrical measurements. The piezoelectric strain constant d31 of the films was determined via optical interferometric measurements on the piezoelectrically forced vibration of silicon cantilevers. Because of the high resistivity of the ZnO samples (higher than 109 Ω cm), piezoelectric excitation down to frequencies of 100 Hz was found to be feasible. The relation between the piezoelectric strain constant and the c-axis orientation distribution of the film [obtained from the full width at half maximum of the x-ray rocking curves at the ZnO (002) diffraction] was determined both experimentally and theoretically. It was found that the experimental effective piezoelectric strain constants are, at most, 60% of the value predicted by the theoretical calculations. It is thought that this discrepancy is due to the cancellation of piezoelectric activity by ZnO grains of opposing polarity. The latter effect and other structural properties of the films are discussed in relation to nucleation and growth of sputtered ZnO films.

Control of Thermal Deformations of Spherical Mirror Segment

Control of thermal deformations of a thin hexagonal spherical mirror segment using discrete and distributed actuators is presented. To determine the effectiveness of the actuators in controlling the thermal deformations of the mirror segment, a comparative study is conducted using two different models of the mirror‐ actuator system: 1) the mirror mounted on kinematic supports and controlled by piezoelectric strips bonded to the rear surface of themirrorand 2 )themirrormounted on force actuators, which are used to supportthemirroraswell as to control the surface deformations of the mirror. The performance of evenly distributed strips and that of strips placed at near-optimal locations obtained using heuristic integer programming are also compared. Both the force actuators and the piezoelectric strips are found to be equally effective in controlling the surface deformations of the mirror. A major drawback of the force actuators is the increase in the overall weight of the system, which is undesirable for space applications. On the other hand, the piezoelectric strips are very lightweight, and hence a large number of such strips can be used to control the surface distortions of the mirror, without imposing a weight penalty. The piezoelectric strips appear to be promising candidates for static shape control of e exible structures in space. Nomenclature b = side of graphite/epoxy plate, m d33 = piezoelectric strain constant, m/V E = root mean square error of the mirror surface distortions f j = control inputs (force applied to the force actuators or the voltage applied to the piezoelectric strips ) h = thickness of graphite/epoxy plate, m m = number of nodes of the e nite element model n = number of force actuators or piezoelectric strips u = correction to the transverse displacement W = middee ection of graphite/epoxy plate, m a ij = ine uence coefe cients w = deformed shape (transverse displacement) of the mirror

Piezoelectric effect of cyanoethylated hydroxyethylcellulose

The piezoelectricity of cyanoethylated hydroxyethylcellulose was investigated. Elastic, piezoelectric, and dielectric relaxations were observed at −80° to −60°C and 0° to 20°C at a frequency of 10Hz. The activation energy is about 9–15 kcal/mol in the low temperature region and about 30–45 kcal/mol at room temperature. These relaxations in the low temperature region may be caused by the motion of the cyanoethyl group and those at room temperature mostly by the motions of the main chain. Cyanoethylated hydroxyethylcellulose has a high piezoelectric strain constant (d 25), which is the largest value among the cellulose derivatives and is almost the same as the value for polyvinylidene fluoride. The electromechanical coupling factor for cyanoethylated hydroxyethylcellulose was small.