Lead Lanthanum Zirconate Titanate Research Articles

Study on electro-optic properties of two-dimensional PLZT photonic crystal band structure

The band characteristics of two-dimensional (2D) lead lanthanum zirconate titanate (PLZT) photonic crystals are analyzed by finite element method. The electro-optic effect of PLZT can cause the refractive index change when it is imposed by the applied electric field, and the band structure of 2D photonic crystals based on PLZT varies accordingly. The effect of the applied electric field on the structural characteristics of the first and second band gaps in 2D PLZT photonic crystals is analyzed in detail. And the results show that for each band gap, the variations of start wavelength, cut-off wavelength and bandwidth are proportional to quadratic of the electric field.

Dielectric response of PLZT ceramics x/57/43 across ferroelectric–paraelectric phase transition

The dielectric properties of lead lanthanum zirconate titanate (PLZT) ceramics (Pb(Zr0·57Ti0·43)O3 + x at% of La, x = 3, 5, 6, 10 and 12) have been measured in the frequency range 1 Hz-1 MHz using the vector impedance spectroscopy (VIS) at different temperatures. All the compositions show both non-dispersive and disper- sive dielectric responses in different temperature regions. The non-dispersive region obeys the universal dielectric response. A low frequency (<1 kHz) relaxation phenomenon with a high value of distribution parameter 'h '( ∼0· 4t o 0·6) has been observed in all the compositions around the temperature corresponding to the maximum dielectric con- stant (T m). The activation energies as calculated from the relaxation and d.c. conduction processes are comparable. The ferroelectric phase transition is diffuse in nature and broadening of the peak increases with La content.

Lasing action and optical amplification in Nd^3+ doped electrooptic lanthanum lead zirconate titanate ceramics

Both single-pass gain and lasing action at 1064.4 nm were observed in ceramic gain media of neodymium doped lanthanum-modified lead zirconate titanate, which exhibits good electrooptic (EO) effect from visible through mid-wave IR band (400 nm to 5.5 µm). These works have removed roadblocks off the way leading to development of long envisioned multifunctional optical devices. The impact of the Nd3+ doping concentration on the EO effect in the Nd3+:PLZT ceramics was studied. The finding of the slowly trailing-off was satisfactorily explained with the rich vacancy-based carrier traps, which are responsible for the long persistent optoenergy storage.

Tunable External Cavity Diode Laser with a PLZT Electro-Optic Ceramic Deflector

A stable tunable diode laser which uses an electrooptic deflector incorporated into a Littrow-type external cavity as a wavelength tunable element is proposed and demonstrated. The deflector is fabricated by lead lanthanum zirconate titanate (PLZT) electrooptic ceramic with high quadratic electrooptic effect. Two half-wave plates and a large angle triangular electrode of PLZT electrooptic ceramic are designed to acquire a high frequency-voltage tuning ratio. By adjusting the voltage applied to the deflector, a large single-mode tuning range of 420 GHz (including mode hops) and a frequency-voltage tuning ratio of 840 GHz/kV have been achieved at 780.5 nm.

Beam steering of external cavity diode laser by an intracavity electro-optic ceramic deflector

A novel beam-steering external cavity diode laser using an intracavity lead lanthanum zirconate titanate (PLZT) electro-optic ceramic deflector is proposed and demonstrated experimentally. The laser consists of a semiconductor laser with single mode fiber coupled output, polarization controller, PLZT electro-optic ceramic deflector, and output concave mirror. By applying proper driven electrical signals on the PLZT electro-optic deflector, the beam deflection angle achieves 5.8 mrad at 1 000 V. A high-speed beam-steering property with less than 120-ns switching time is also observed. Moreover, a good beam quality with Gaussian spatial profile and a linear polarization state are obtained.

Ceramic-Controlled Piezoelectric Bulk Implanted with Pt Wire Based on BaTiO3 (Optical Microscopy, SEM, EDS) and PLZT (Optical Bi-dimensional Characterization)

This paper describes the formation of poled bulk ferroelectric ceramics made of Lead Lanthanum Zirconate Titanate (PLZT) and Barium Titanate (BaTiO3). These ceramics were implanted during their fabrication with a platinum wire (Pt-wire), which worked as an internal electrode. This internal electrode was verified by means of optical microscopy, SEM, and EDS of the Barium Titanate (BaTiO3) ceramic to determine some chemical reaction. The analysis was checked only in BaTiO3 because it is the most common ferroelectric ceramic. Finally, the photovoltaic signal was measured in PLZT with the Pt-wire in a bi-dimensional experimental setup, with a resolution of 50 μm.

Effect of dead layer and strain on the diffuse phase transition of PLZT relaxor thin films

Bulk relaxor ferroelectrics exhibit excellent permittivity compared to their thin film counterpart, although both show diffuse phase transition (DPT) behavior unlike normal ferroelectrics. To better understand the effect of dead layer and strain on the observed anomaly in the dielectric properties, we have developed relaxor PLZT (lead lanthanum zirconate titanate) thin films with different thicknesses and measured their dielectric properties as a function of temperature and frequency. The effect of dead layer on thin film permittivity has been found to be independent of temperature and frequency, and is governed by the Schottky barrier between the platinum electrode and PLZT. The total strain (thermal and intrinsic) in the film majorly determines the broadening, dielectric peak and temperature shift in the relaxor ferroelectric. The Curie–Weiss type law for relaxors has been further modified to incorporate these two effects to accurately predict the DPT behavior of thin film and bulk relaxor ferroelectrics. The dielectric behavior of thin film is predicted by using the bulk dielectric data from literature in the proposed equation, which agree well with the measured dielectric behavior.

Thermal lensing investigation on bulk ceramics and thin-film PLZT using visible and far-infrared laser beams

The real-time thermo-optical properties of thin-film relaxor ferroelectric (9/65/35) lead lanthanum zirconate titanate (PLZT) films (∼2μm) were investigated and compared to identical composition of thick PLZT ceramics (∼1mm). Since PLZT absorbs strongly in the far-infrared, a CO2 laser beam (λ=10.6μm) was used to create a Gaussian temperature distribution at the surface of the material, emulating a lens. Subsequently, a low power visible He–Ne laser, travelling along the same path as the CO2 laser, probed the optical properties of the induced PLZT thermal lens. It was found that identical composition thin-film and thick PLZT ceramics have opposite thermal lensing behaviors. An explanation of this phenomenon is provided from basic physical concepts.

ChemInform Abstract: Fabrication of Transparent Lead Lanthanum Zirconate Titanate (PLZT) Ceramics from Fine Powders by Two-Stage Sintering.

ChemInform Abstract: Fabrication of Transparent Lead Lanthanum Zirconate Titanate (PLZT) Ceramics from Fine Powders by Two-Stage Sintering.

Temperature dependence of electromechanical properties of PLZT x/57/43 ceramics

The compositions of lead lanthanum zirconate titanate PLZT [Pb(Zr0.57Ti0.43)O3 + x at% of La, where x = 3, 5, 6, 10 and 12] have been synthesized using mixed oxide route. The temperature dependent electromechanical parameters have been determined using vector impedance spectroscopy (VIS). The charge constant d 31 and elastic compliance s E11 show a peak in all the samples at a temperature T mt much below the ferroelectric — paraelectric transition temperature, whereas the series resonance frequency f s shows a dip at these temperatures. The Poisson’s ratio σ E increases with temperature T showing a broad peak at a temperature higher than T mt . The voltage constant g 31 decreases and the planar coupling coefficient K p remains constant up to half of the T mt and then falls sharply with T. Half of the T mt can, therefore, be used for specifying the working temperature limit of the piezoceramics for the device applications.

A Piezoelectric Plethysmograph Sensor Based on a Pt Wire Implanted Lead Lanthanum Zirconate Titanate Bulk Ceramic

This work reports on the development of a Lead Lanthanum Zirconate Titanate (PLZT) bulk ferroelectric poled ceramic structure as a Piezoelectric Plethysmograph (PZPG) sensor. The ceramic was implanted during its fabrication with a platinum (Pt) wire which works as an internal electrode. The ceramic was then submitted to an experimental setup in order to validate and determine the Pt-wire mechanical effects. This PZPG sensor was also mounted on a finger splint in order to measure the blood flow that results from the pulsations of blood occurring with each heartbeat. Fingertip pulses were recorded jointly with an ECG signal from a 25 year old male to compare the time shift; the PZPG sensor guarantees the electrical isolation of the patient. The proposed PZPG has several advantages: it can be adjusted for fingertip measurements, but it can easily be extended by means of spare bands, therefore making possible PZPG measurements from different body locations, e.g., forehead, forearm, knee, neck, etc.

Characteristics of Electron Emission from a (Pb,La)(Zr,Ti)O3 Ferroelectric Cathode

The properties of electron emission from a poled lead lanthanum zirconate titanate (PLZT) ferroelectric cathode have been investigated on the dependence of operating parameters such as the driving voltage, the vacuum pressure, the diode gap distance, and the diode acceleration voltage. The threshold electric field for electron emission from the cathode is about 6 kV/cm and the emitted current increase with increase in the driving voltage. A maximum current of 37 A/cm2 has been detected when the driving voltage is -1.4 kV and the gap distance is 20 mm. The electron emission is considered to be initiated by field emission and then possibly be enhanced by the surface plasma. To confirm the detailed emission process, however, further experimental study should be necessitated.

18Oxygen diffusion in polycrystalline lead lanthanum zirconate titanate

Abstract18O oxygen tracer diffusion coefficients and activation energies were determined in polycrystalline PLZT (lead lanthanum zirconate titanate) with varying La concentration in the temperature range of 500 °C to 800 °C. For this purpose the isotope exchange method and Secondary Ion Mass Spectrometry (SIMS) depth profiling were used. As a novel approach a chemically reduced sample was prepared by anneal‐ ing at low oxygen partial pressure (p (O2) ≈ 10–13 Pa). Subsequently the sample was thermally charged with 18O, too. Results indicate a higher diffusion rate in the reduced sample than in as‐received PLZT thus leading to the assumption that the diffusion mechanism in PLZT is vacancy driven despite the strong donor doping of the perovskite lattice. (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Opacity Sensor Based on Photovoltaic Effect of Ferroelectric PLZT Ceramic With Pt Wire Implant

This work reports the formation of a ferroelectric poled bulk ceramic structure as opacity sensor (OPS) and the improved photovoltaic output of the lead lanthanum zirconate titanate (PLZT) employed. This ceramic was implanted during its fabrication with a platinum wire (Pt-wire) which works as an internal electrode. Photovoltaic current have been measured in PLZT with Pt-wire under chopped LASER beam illumination. This photovoltaic current was measured on the upper face of a sensor in order to obtain a characterization curve. Different thin materials were put on the OPS in order to determine its opacity according to their thickness and viscosity. Opacity is a condition in which a material partially or completely impedes the passage of light beam. The results indicated that the photovoltaic current response was less than 700 pA at 160 mW/cm2 maximum power of illumination; 2-D scans were obtained from fruit tissues, vegetal oils and thin materials at 160 mW/cm2 of illumination in order to get a representation of opacity images.

Multi-physics field models of photostrictive unimorphs and heterogeneous bimorphs subjected to light illumination and mechanical loading

This paper presents novel constituent equations for photostrictive unimorphs and heterogeneous bimorphs by considering multi-physics fields. Although the formulation is conducted using the lead lanthanum zirconate titanate ceramics (PLZT) polarized in 0-3 direction subjected to light illumination and mechanical loading, the results may be extended to other photostrictive materials or degenerated to piezoelectric ceramics. In the present formulation, photo-induced electrical, thermal and mechanical fields in PLZT ceramics are studied first, and then one-dimensional opto-thermo-piezoelectric equations for 0-3 polarized PLZT and other photostrictive materials are discussed. On the basis of the photo-induced multi-physics equations, 0-3 polarized PLZT unimorphs and bimorphs are investigated and the associated constituent equations are derived. The numerical results calculated using the present formulations are then compared with those available in the literatures to validate the derived novel constituent equations.

High-Temperature, High-Dielectric-Constant Capacitors for Power Inverters in Hybrid Electric Vehicles

Future availability of high-temperature power inverters will advance the market share for hybrid vehicles that are highly fuel efficient and environmentally friendly. Capacitors have a significant influence on inverter lifetime, reliability, cost, and temperature of operation. Advanced power inverters require capacitors that operate under high voltage conditions at under-hood conditions and yet have minimal footprint. This need can be realized by embedding high-permittivity dielectrics within a printed wire board (PWB). The “film-on-foil” approach, where the dielectric is deposited on base-metal foil, is a promising method for embedding the capacitors within a PWB. We have deposited high-permittivity films of lead lanthanum zirconium titanate (PLZT) on nickel foils by a chemical solution deposition technique. These prefabricated film-on-foil dielectric sheets can be embedded into PWBs for inverter applications. Among the many challenges in fabricating these sheets is avoiding a reduction in capacitance density from the formation of a parasitic, low-permittivity, interfacial layer of nickel oxide during thermal processing of the PLZT. We inserted a conductive oxide buffer layer between the PLZT dielectric film and the nickel foil to hinder formation of the deleterious interfacial oxide. For PLZT films deposited on Ni foils, we measured a dielectric constant of 1300 (at 25°C) and 1800 (at 150°C), leakage current density of 6.6 × 10−9 A/cm2 (at 25°C) and 1.4 × 10−8 A/cm2 (at 150°C), and breakdown field strength &amp;gt;2.0 MV/cm (at 25°C). Film-on-foil dielectric films were thermally cycled (≈1000 cycles) between −50°C and +150°C with no measurable degradation in dielectric constant. Recently, we fabricated and measured a capacitance of ≈1 μF on a 12-mm-diameter film-on-foil dielectric layer. The fabrication procedures and dielectric properties of film-on-foil PLZT samples are presented in this talk.

High-Dielectric-Constant PLZT Films on Metal Foils for Embedded Passives

Ceramic film capacitors with high dielectric constant and high breakdown strength would result in advanced power electronic devices with higher performance, improved reliability, and enhanced volumetric and gravimetric efficiencies. We have grown ferroelectric films of lead lanthanum zirconate titanate (PLZT) on base metal foils by chemical solution deposition. Their dielectric properties were characterized over the temperature range between −50 and 150°C. We measured a dielectric constant of ≈700 and dielectric loss of ≈0.07 at −50°C and a dielectric constant of ≈2200 and dielectric loss of ≈0.06 at 150°C. At room temperature, we measured a leakage current density of ≈6.6 × 10−9 A/cm2, mean breakdown strength of 2.6 MV/cm, and energy density &amp;gt;85 J/cm3. A series of highly accelerated lifetime tests (HALT) was performed to determine the reliability of these PLZT film-on-foil capacitors under high temperature and high field stress conditions. Samples were exposed to temperatures ranging from 100 to 150°C and electric fields ranging from 8.7 × 105 V/cm to 1.3 × 106 V/cm during the HALT testing. Breakdown behavior of the samples was evaluated by Weibull analysis. The mean time to failure was projected to be &amp;gt;3000 h at 100°C with a dc electric field of ≈2.6 × 105 V/cm.

Developed and Experimental Evidence of a Ceramic-Controlled Piezoelectric Bulk Implanted with Pt Wire Based on PLZT

This work reports on the formation of a Lead Lanthanum Zirconate Titanate bulk ferroelectric poled ceramic structure as ceramic-controlled piezoelectric, this ceramic was implanted during its fabrication with platinum wire that operates as an internal electrode. The CCP was submitted in two experimental setups to validate and determine the Pt-wire optical and mechanical effects. Dielectric constant was determined on ceramic-controlled piezoelectric with and without Pt wire.

ChemInform Abstract: Preparation and Structural Characterization of Rare‐Earth Doped Lead Lanthanum Zirconate Titanate Ceramics.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Improved dielectric properties of lead lanthanum zirconate titanate thin films on copper substrates

Thin films of lead lanthanum zirconate titanate (PLZT) were directly deposited on copper substrates by chemical solution deposition and crystallized at temperatures of ~ 650 °C under low oxygen partial pressure ( pO 2 ) to create film-on-foil capacitor sheets. The dielectric properties of the capacitors formed have much improved dielectric properties compared to those reported previously. The key to the enhanced properties is a reduction in the time that the film is exposed to lower pO 2 by employing a direct insertion strategy to crystallize the films together with the solution chemistry employed. Films exhibited well-saturated hysteresis loops with remanent polarization of ~ 20 μC/cm 2, dielectric constant of > 1100, and dielectric loss of < 0.07. Energy densities of ~ 32 J/cm 3 were obtained at a field of ~ 1.9 MV/cm on a ~ 1 μm thick film with 250 μm Pt electrodes.