Improving the fatigue endurance of lead zirconate titanate thin films through PbO interfacial modification

The effects of the modification of electrode/ceramic interfaces through a chemical solution deposition-derived PbO buffer layer on the fatigue endurance of lead zirconate titanate（PZT） thin films were investigated.The grain size and the surface roughness of the PZT films increased through PbO interfacial modification.Moreover,the PZT films with PbO interfacial modification had a better crystallographic structure and no evident secondary phases were observed.While the remanent polarization and dielectric constant were reduced,the fatigue endurance was improved.Based on the results,the mechanism for the fatigue endurance improvement was discussed.

Lead zirconate titanate behaviors in an LDMOS

The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current–gate voltage （ID-VG） memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor （LDMOS）. The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.

Lead zirconate(PbZrO_(3))embedded in natural rubber as electroactive elastomer composites

Perovskite lead zirconate(PbZrOz)was synthesized in an orthorhombic form at a temperature below the Curie temperature,Tc.The orthorhombic form is a noncentrosymmetric structure which is capable of spontaneous polarization.Fourier transform infrared(FTIR)spectra and X-ray diffraction(XRD)patterns confirm the siuccessful synthesis of the lead zirconate;and scanning electron microscopy(SEM)micrographs indicate that PbZrO_(3) particles are moderately dispersed in the natural rubber(NR)matrix.Without an electrical field,the particles merely act as a ferroelectric fller,which can absorb and store additional stress.Under an electrical field,particle induced dipole motents are generated,leading to interparticle interaction and a sub-stantial increase in the storage modulus.At a small amount of lead ziroonate part iculates present in the natural rubber matrix,at a volume fraction of 0.007306,the electrical conductivity increases dramatically by nearly two orders of magnitude at the electrical frequency of 500 kHz.

An Improved Cymbal Hydrophone Made of Lanthanum-Modified Lead Zirconate Titanite

Lanthanum-modified lead zirconate titanite （PLZT） piezoelectric ceramics has higher piezoelectric and dielectric properties compared with the common lead zirconate titanite （PZT） ceramics. These properties endue the cymbal hydrophones made of PLZT usually with stable performance but lower receiving sensitivity. In order to improve the sensitivity, through a static analysis on hydrophone we did some changes for the PLZT hydrophone by reducing the radius of the piezoelectric ceramics and sealing its boundary. Furthermore, ANSYS simulations were made, and the experiments for the improved PLZT hydrophone and the original one were carried out in water pool. The results show that the receiving sensitivity of the improved cymbal hydrophone made of PLZT is 3 -4 dB higher than that of the original, and that the frequency response still keeps flat within 18 kHz band.

FABRICATION OF PIEZOELECTRIC BIMORPH USING LEAD ZIRCONATE TITANATE THIN FILM DEPOSITED BY HYDROTHERMAL METHOD

In order to describe the characteristics of piezoelectric bimorph, properties of lead zirconate titanate （LZT） film are studied by X-ray diffraction （XRD） and scanning eletron microscope （SEM）. The ratio of PbTiOJPbZrO3 in LZT is 53/47, which is around morphotropic phase boundary （MPB）. LZT film is composed of cubic particles with the average size of 5 ~ma. Density of thin film is figured out through the datum measured in experiments. The displacement model used to analyze the driving ability of bimorph is set up, and the effect of elastic intermediate layer is taken into account. Piezoelectric coefficient of LZT film is worked out by using the displacement model. Experiments of driving ability show that deformation of bimorph free end does not increase with times of crystal growth processes and the maximum deformation is obtained after two times crystal growth processes. Finally, the ferroelectric property of the bimorph is investigated and coercive voltage of the bimorph is obtained.

A new hybrid piezoelectric ultrasonic motor with two stators

A new hybrid piezoelectric ultrasonic motor, which consists of one rotor and two stators, was proposed in this paper. In order to match the resonance frequencies of longitudinal vibration and torsional vibration excited in the stators, a symmetrical structure was adopted in design of the motor. A so-called mass matching method, namely adding two rings to the outside circumference of the two stators respectively, was used to adjust the resonance frequencies of these two vibrations. A finite element model was developed using ANSYS software for the purpose of analyzing the resonance frequencies of longitudinal vibration and torsional vibration as well as the function of the adjusting rings. The results show that the resonance frequency of torsional vibration varies with the position of the ring, but the resonance frequency of longitudinal vibration changes little. By means of adjusting the mass and the position of the rings, the first order resonance frequency of longitudinal vibration is coincided with that of torsional vibration and the value is 20.75kHz. An experimental prototype motor was fabricated according to the analytical results and its performance is in agreement with the theoretical predictions. The speed of motor reaches the maximum 92r/min at the working frequency 19.0kHz.

Design and Characterization of a Low-Cost Piezoelectric Vibration Energy Harvester with Bulk PZT Film

To improve the efficiency of MEMS piezoelectric vibration energy harvesters(PVEHs), the bulk lead zirconate titanate(PZT) has been used to substitute the thin film PZT for the higher mechanical-electrical coupling coefficients. The expensive equipment of micromachining set a high entry barrier on the research of PVEHs with high efficiency. To solve this issue, this paper developed an efficient PVEH with bulk PZT using common precision machining, whose dimensions and electrical outputs are comparable to the MEMS devices. After numerically analyzing the effects of the length ratio of the proof mass to the harvester on the output power, a compact PVEH consisting of a cantilevered uni-morph and a tungsten proof mass was designed. Simulations show that the mechanical damping ratio and the thickness have little effects on the optimized length ratio. By using a uni-morph with the copper structural layer of about 80-90μm and the bulk PZT-5 H layer of 139μm, a low-cost harvester prototype was assembled. The key parameters of the prototype were experimentally identified and compared with the theoretical predictions. Under the harmonic base excitation of 0.4 g(where g = 9.8 m/s^2) at 160 Hz, the maximum output power of the prototype is about 76.7μW, with the normalized power density of about 3.35 mW/cm^3/g^2. Under base excitation of 0.4 g at 159 Hz, the prototype charged a 680μF capacitor from 0 to 4.84 V in about 154 seconds.

Phonon dispersion calculations using the Vaks model in antiferroelectric lead zirconate

The calculations of low-energy phonon dispersion relations in lead zirconate(PZ)have been carried out using the Vaks model.This model takes into account only five low-energy phonon modes and their interactions.It has been shown that this model allows to achieve good agreement not only between calculated and experimental transverse acoustic phonon dispersion but also between their temperature dependences.It has been shown 5-mode system,which describes low-energy phonon dispersion in PZ,is close to unstable state.Even a little change of interaction parameter can lead to lattice instability with nonzero wave vector qcrit.Wave vector qcrit could have any value,including irrational one.In this case,system will undergo an incommensurate phase transition.

Properties of La_2O_3-Doped PNSZT Piezoelectric Ceramics Having Tetragonal and Rhombohedral Coexistent Phases

The relationship between composition and the electric mechanical properties for La2O3-doped lead niobium stibium zirconate titanate(La2O3-doped PNSZT) piezoelectric ceramics,in which there are tetragonal and rhombohedral coexistent phases, was studied. A series of piezoelectric ceramics with good properties was obtained, having dielectric constants (ε= 1500 ~ 2500), plane electromechanical coupling factor(Kp = 0.45 ~ 0.65), mechanical quality factor( Qm = 500 ~ 1600). These materials are used for making ultrasonic sensor and filter, and marine acoustic launching and receiving device, and so on. It has been explored that the influence of composition on the lattice constant and phase composition of La2O3-doped PNSZT piezoelectric ceramics by XRD(X-ray diffraction) . The character of dielectric constant changing of La2O3-doped PNSZT piezoelectric ceramics before polarization and after polarization was studied. The affecting mechanism about composition on the electric machine properties of phase coexistent La2O3-doped PNSZT piezoelectric ceramics was analyzed and discussed.

Tunable polarization-drived superior energy storage performance in PbZrO_(3) thin films

Antiferroelectric PbZrO_(3)(AFE PZO)films have great potential to be used as the energy storage dielectrics due to the unique electric field(E)-induced phase transition character.However,the phase transition process always accompanies a polarization(P)hysteresis effect that induces the large energy loss(Wloss)and lowers the breakdown strength(EBDS),leading to the inferior energy storage density(Wrec)as well as low efficiency.In this work,the synergistic strategies by doping smaller ions of Li^(+)–Al^(3+)to substitute Pb2+and lowering the annealing temperature(T)from 700 to 550℃are proposed to change the microstructures and tune the polarization characters of PZO films,except to dramatically improve the energy storage performances.The prepared Pb_((1−x))(Li_(0.5)Al_(0.5))_(x)ZrO_(3)(P_((1−x))(L_(0.5)A_(0.5))_(x)ZO)films exhibit ferroelectric(FE)-like rather than AFE character once the doping content of Li^(+)–Al^(3+)ions reaches 6 mol%,accompanying a significant improvement of W_(rec) of 49.09 J/cm^(3),but the energy storage efficiency(η)is only 47.94%due to the long-correlation of FE domains.Accordingly,the low-temperature annealing is carried out to reduce the crystalline degree and the P loss.P_(0.94)(L_(0.5)A_(0.5))_(0.06)ZO films annealed at 550℃deliver a linear-like polarization behavior rather than FE-like behavior annealed at 700℃,and the lowered remanent polarization(P_(r))as well as improved E_(BDS)(4814 kV/cm)results in the superior Wrec of 58.7 J/cm^(3) and efficiency of 79.16%,simultaneously possessing excellent frequency and temperature stability and good electric fatigue tolerance.

Effect of lanthanum,neodymium on piezoelectric,dielectric and ferroelectric properties of PZT

The effect of La^(3+)and Nd^(3+)on piezoelectric,dielectric and ferroelectric properties of PZT(Pb(Zr_(0.53)Ti_(0.47))O_(3))was studied.The powders were prepared by“wet-chemical”route followed by calcination at 800℃for 4 h.XRD analysis of the calcined powders confirms the tetragonal phase in the undoped PZT,which gradually decreases with the dopant concentration and the appearance of rhombohedral phase simultaneously.SEM study of sintered pellets reveals the decrease in grain size with the increase in dopant concentration beyond 0.02 mol Nd^(3+)and 0.03 mol La^(3+)respectively.The piezoelectric constant(d_(33))and dielectric properties were maximum for 0.02 mol Nd^(3+)and 0.03 mol La^(3+)respectively.The remnant polarization of La^(3+)-doped sample was higher than Nd^(3+)-doped sample,and the sample with combined dopants shows intermediate remnant polarization(P_(r)).Based on the above study,it is concluded that La^(3+)is more effective than Nd^(3+),including in a mixture of La^(3+)and Nd^(3+)dopants.

DIELECTRIC AND FERROELECTRIC PROPERTIES OF(1-x)Pb(Mg_(1/3)Nb_(2/3))O_(3)-xPbZrO_(3)CERAMICS WITH CATION ORDER

Electrical properties and the B-site cation order were investigated in the(1-x)Pb(Mg_(1/3)Nb_(2/3))O_(3)-xPbZrO_(3)(0≤x≤0.25)solid solution ceramics.It was found that long range 1.1 B-site cation order can be developed through slow cooling during sintering in the solid solution with compositions around x=0.10.The observed long range cation order is in sharp contrast to previous studies where a disordered structure was invariably resulted in the(1-x)PbeMg_(1/3)Nb_(2/3)TO_(3)-xPbZrO_(3)solid solution.The ceramics with cation order display dielectric and ferroelectric properties similar to those disordered ceramics reported in literature.The dielectric properties were also compared in detail to our previous PbeMg_(1/3)Zr_(2x/3)Nb_(2)(1-x)/3TO_(3-x)/3 ceramics where Zr^(4+)is designed to substitute Nb^(5+)only.The results were discussed on the basis of the relationships between cation order and electric dipole order.