Showing papers on "Lead zirconate titanate published in 1985"

Piezoelectric Composite Materials for Ultrasonic Transducer Applications. Part I: Resonant Modes of Vibration of PZT Rod-Polymer Composites

Abstract: Abstmcr-The objective of the present work was to gain a deeper mensions of the transducer are much smaller than the understanding of the behavior of lead zirconate titanate (PZT) polymer composites for applications such as ultrasonic medical diagnosis in the megahertz frequency range. These composites were originally developed for low-frequency hydrophone applications. The PZT rod-polymer composites have been prepared with five to 30 volume percent PZT using 0.28 mm and 0.45 mm rods. In a disc of PZT rod-polymer composite material, there are three principal types of resonance: the planar mode, the thickness mode, and various lateral modes caused by the regular periodicity of the PZT rod in the composite. These resonance modes have been studied with the following techniques: 1) electrical impedance measurement as a function of frequency and 2) laser probe dilatometry of the dynamic displacement as a function of frequency and position in the composite lattice. The observed resonance behavior is found to be a result of lateral interactions in the composite through the epoxy medium. The effect of temperature on the electromechanical properties of the composite has also been investigated. Implications of these results for optimizing the design of ultrasonic transducers are discussed.

Piezoelectric Composite Materials for Ultrasonic Transducer Applications. Part II: Evaluation of Ultrasonic Medical Applications

Abstract: Abstmct-The electro-acoustic properties of Lead zirconate titanate (PZT) rod-polymer composites relevant for ultrasonic transducer applications are reported. Acoustic impedance of the composite materials was measured by three different techniques in the frequency range 0.33.5 MHz. Dependence of the acoustic impedance as a function of volume fraction of PZT and frequency was also modeled theoretically. Time-delay spectrometry was employed to calibrate the free-field transmitting and receiving voltage responses of the composite materials. The acoustic impedance of the composite materials was in the range of 3-10 M rayl. The figure of merit in the receiving mode of composite materials was three times that of PZT. The figure of merit for a 20percent PZT composite (2 = 7.3 M rayl) was further enhanced by 50 percent using a single-layer impedance transformer of lucite (2 =3.3 M rayl). These composite materials were molded into curved shapes by simple thermal process to fabricate focused transducers. The axial and lateral beam profiles of focused composite transducers are presented.

Structural Dependence on Sintering Temperature of Lead Zirconate‐Titanate Solid Solutions

Abstract: Pb(Zr /SUB 0.525/ Ti /SUB 0.475/ )O3 piezoceramics, both unmodified and doped with 2 wt% Bi2O3 or Nb2O5, were prepared by the usual techniques, using sintering temperatures from 900 to 1250C. The microstructural data showed that the sintering temperature which produces minimum porosity is altered by the oxide additions. X-ray diffraction demonstrated the coexistence of both ferroelectric phases. The lattice parameter measurements showed that the tetragonal and rhombohedral unit cells of the two ferroelectric phases depend on the sintering temperature.

Fractoemission from lead zirconate-titanate

Abstract: We present measurements of the electron, positive ion, and photon emission accompanying the fracture in vacuum of poly-crystalline 95/5 lead zirconate-titanate. The intensities of the charged-particle components of this fractoemission are shown to depend strongly on the direction (relative to the direction of fracture) and magnitude of polarization. The most intense emission is observed when the fracture surfaces are perpendicular to the polarization direction. The emission intensity increases monotonically with polarization. These results are interpreted in terms of a model involving charge separation on the fracture surfaces leading to a microdischarge during fracture. Implications to the interpretation of triboluminesence effects are discussed.

One-dimensional regular arrays of antiphase domain boundaries in anti-ferroelectric tin-substituted lead zirconate titanate (PZT) ceramics

Abstract: The existence of one-dimensional regular arrays of antiphase domain boundaries has been confirmed in tin-substituted PZT ferroelectrics of ABO3 perovskite structure (Pb0.99{[(Zr1−ySn y )1−xTi x ]0.98Nb0.02}O3,x=0.03 and 0.04,y=0.20) by means of electron diffraction and lattice imaging. Calculation has been made of the number of satellite spots in the diffraction patterns and their positions determined. They coincide well with the electron diffraction patterns experimentally obtained. The finding proves the relative elongation in one dimension of the ferroelectric unit cell caused by a parallel array of electrical dipoles, as compared to the cell of an anti-parallel array of dipoles.

Lead zirconate titanate ceramics

Abstract: Lead zirconate titanate ceramics comprise from about 92 to 99.0 weight pent of lead zirconate and lead titanate in ratio from 0.505 to 0.54:0.495 to 0.46 respectively, from about 0.5 to about 2 weight percent of one or more fluorides or chlorides of an alkali metal or alkaline earth except francium or radium, and 0.5 to 6 weight percent of one or more oxides of magnesium, barium, chromium, scandium, aluminum, lanthanium, praesodymium, neodymium or samarium. The ceramic after pressing is annealed at a temperature from about 1050° to 1350° C. Ceramic elements made from the above ceramics are useful as sonar and microphone transducers.

Effect of zirconium concentration and doping with Sr and Al on the sintering and electromechanical properties of lead zirconate titanate ceramics

Abstract: The effect of small additions of Sr and Al on the dielectric and electromechanical properties of lead zirconate titanate (PZT) ceramics of different Zr/Ti ratios has been studied. Dielectric constants greater than 1200 and reached 1500 for polarised doped samples were obtained along with planar couplings of about 0.5. Variations of dielectric constant were found to be porosity dependent. Doping enhanced sintering, caused a shift in the morphotropic boundary toward the rhombohedral side, decreased the lattice distortion from cubic symmetry and caused grain growth inhibition. Anomalous density increase for Sr doped samples took place above 1150°C while samples doped with both Sr and Al showed such anomaly over all the investigated temperature range.The results were interpreted on the basis of the role played by crystal defects, the fluxing effects of the doping materials, and Coble's model of bulk diffusion of vacancies from pores to grain boundaries in relation to wall mobility.

Piezoelectric acceleration sensor

Abstract: PURPOSE: To increase a charge sensitiveness and an electrostatic capacity by combining a laminated piezoelectric ceramic body laminated with a plurality of piezoelectric ceramic elements each having a thickness not more than a specified value and subjected to a polarization process with a deadweight to form an acceleration sensor. CONSTITUTION: A piezoelectric ceramic element 11 is manufactured to a 0.5mm or less thick ringed configuration from a ceramic piezoelectric material using lead zirconate titanate or the like. Then, a plurality of the elements 11 are laminated intervening internal electrodes 14 and combined with an insulating protective film 15, an external electrodes 12, an insulating board 13 and the like to form a laminated piezoelectric ceramic body 10. The body 10 is built in a frame 8 together with a deadweight 2, a pre-loading bolt 4 and the like to constitute a piezoelectric acceleration sensor. Therefore, reducing the thickness of each piezoelectric ceramic element can improve a charge sensitiveness and an electrostatic capacity to extremely increase an output voltage and reduce a cost. COPYRIGHT: (C)1986,JPO&Japio

New Ceramic Electrode for Piezoelectric Buzzer

Abstract: Electrical conductive oxide for electrode were investigated, and the piezoelectric characteristics were measured for lead zirconate titanate (PZT) resonator with the conductive oxide. Printable pastes were made using conductive oxides having perovskite type structure such as BaPbO3, BaPb1.2O3, BaPb0.8Bi0.2O3, BaPb0.8Sb0.2O3 and La0.5Sr0.5CoO3 with glass frits and organic vehicles. The electrical resistivities of these pastes were measured at room temperature by four probe method, which were 1.4×10-2 ohm–cm for BaPbO3 paste and 2.3×10-2 ohm–cm for La0.5Sr0.5CoO3 paste. The piezoelectric resonators were obtained with Kp=39%, tan δ=3.2% and C=24nF for electrode of BaPbO3 paste and with Kp=31%, tan δ=6.8% and C=39nF for electrode of La0.5Sr0.5CoO3 paste.

Fabrication of Transparent PZLT Ceramics by Atmosphere Sintering

Abstract: Pressure-less fabrication process of lanthanum-modified lead zirconate titanate (PLZT) electrooptic ceramics has been developed. Fine-particle PLZT powders having excellent reaction and homogeneous composition were fabricated by a chemical preparation method using inexpensive starting materials. Optically transparent PLZT ceramics were obtained by sintering this chemically-prepared powder under O2-gas flow and atmosphere PLZT powder.

A piezo-electric ceramic composition for resonator in electrical wave filters.

Abstract: A new piezo-electric ceramic composition for resonator in electrical wave-filters are now provided, which essentially consists of a modified or unmodified lead zirconate titanate and, as additives, 1.5 to 4.5% of tungsten oxide (WO3) and 0.1 to 0.5% of chromium oxide (Cr2O3) based on the total weight of the composition, and which shows in combination a low mechanical quality factor (Qm) value of not more than 300, a high electromechanical coupling coefficient, a high dielectric constant, and improved temperature and time stabilities of the resonant frequency for the filter resonator. The wave-filter produced from the new composition exhibits improved group-delay-time characteristics.

Experimental and Theoretical Aspects of Frequency-Domain Photopyroelectric Spectroscopy of Condensed Phases (PPES), a New, Simple and Powerful Spectroscopic Technique

Abstract: Photoacoustic Spectroscopy (PAS) has been used extensively in recent years with conventional microphones and piezoelectric detectors as signal transducers The commonest piezoelectric transducers are usually made out of piezoelectric ceramic (eg, lead zirconate titanate, PZT [1 – 3]) These ceramics exhibit a much higher frequency response than microphone transducers, and thus they became dominant in photoacoustic applications where fast transducer response is required, such as pulsed laser PAS [4] Very recently Tam and Coufal [5] and Coufal [6] used polyvinylidene difluoride (PVDF) thin film piezoelectric transducers for pulsed and modulated photoacoustics These films have distinct advantages over PZT transducers, the most important of which being their much higher, essentially flat frequency response between DC and tens of MHz [7] In addition to piezoelectric behaviour, PVDF thin films (Pennwalt KYNAR™) exhibit strong pyroelectric properties [8] and, therefore, they can be used as detectors of thermal radiation Coufal [6] utilized the pyroelectric character of 9 ym thin PVDF films to obtain pulsed and low modulation frequency spectra of Nd2O3 doped poly(methyl methacrylate) films

Structural dependence on sintering temperature of lead zirconate-titanate solid solutions

Abstract: Pb(Zr /SUB 0.525/ Ti /SUB 0.475/ )O3 piezoceramics, both unmodified and doped with 2 wt% Bi2O3 or Nb2O5, were prepared by the usual techniques, using sintering temperatures from 900 to 1250C. The microstructural data showed that the sintering temperature which produces minimum porosity is altered by the oxide additions. X-ray diffraction demonstrated the coexistence of both ferroelectric phases. The lattice parameter measurements showed that the tetragonal and rhombohedral unit cells of the two ferroelectric phases depend on the sintering temperature.

Design, Fabrication and Evaluation of Performance of Plzt Electro-Optic Modulator

Abstract: In this paper the design, fabrication and the testing of PLZT Electro-optic modulator and its application in optical communication is discussed.The PLZT which stands for the Lead Lanthanum Zirconate Titanate Pbi-xLaxZrm' Tin)03, is obtained by doping Lead Zirconate Titanate with La. The PLZT ceramic is itself a solid solution of Lead Titanate and Lead Zirconate. Using this material, an Electro-optic (EO) modulator has been designed, fabricated and tested. The mode of operation is transverse. Using this device, the half-wave retardation voltage (V) is measured as a function of electrode spacing and also the frequency response of the material.Half-wave voltage was found to be proportional to the electrodes spacing d). Material responded without attenuation upto 1 MHz. A prototype laser communication system was made and tested for the two-way voice/music communication.