Preparation Of Lead Zirconate Titanate Research Articles

Pyroelectric characteristics of thin PbTiO3 and la-modified PbTiO3 films on platinum films for infrared sensors

In this work, we grew lead titanate (PbTiO3) and La-modified PbTiO3 thin films on platinized silicon (Si(100)) substrates under controlled substrate temperature and ambient by a modified jet-vapor deposition (JVD) process described in this paper. The x-ray diffraction patterns obtained from these films showed a single-phase perovskite structure. We examined locally homogeneity and thickness of these films through the comparative use of laser Raman spectroscopy. We also collected Raman and x-ray data on pure PbTiO3, as well as prepared lead zirconate titanate (PZT) (54/46), and PZT (50/50) films using the JVD process. This paper discusses the temperature variations of the pyroelectric and dielectric properties of three compositions of La-modified PbTiO3 films containing 5.2% to 15% of La, respectively, with a view toward studying the effect of La in place of Pb on these electrical properties. We detected significant pyroelectric currents on all three La-modified PbTiO3 films before performing poling treatments, and observed pyroelectric coefficeints as high as 84 nC/cm2·°C in the poled La-doped PbTiO3 films containing 5.2% La. The pyroelectric coefficient and dielectric constant varied significantly with La content. We compared the calculated figures of merit, which were based on the measured physical properties, with pure PbTiO3 as well as PZT and lead lanthanide zirconate titanate (PLZT) films. These properties just described illustrate that these films would be suitable for IR detectors.

The investigation of Pb-sufficient buffer layer on the ferroelectric properties in Pt/PZT/Pt structure

In this study, we prepared lead zirconate titanate (PZT) thin film with buffer layer by sol-gel method to investigate the role of interface composition on the ferroelectric behavior of PZT thin film. About 50-nm-thick PZT buffer layer containing various amount of excess Pb was served as an interfacial layer. After drying the buffer layer, about 200 nm thick PZT film containing 15% excess Pb was over-deposited. According to the increase of excess Pb content for the interfacial PZT layer, an integral PZT film showed an improvement of crystalline quality and negligible polarization fatigue behavior even after repeated 109 cycles in Pt/PZT/Pt structure. Therefore, we could believe that compositional and crystalline state of PZT buffer layer contacting Pt substrate has an important role on the entire film properties.

Preparation of Lead Zirconate Titanate (PZT) Powder Using Gel Entrapment Technique

The paper describes the preparation of PZT powder from a mixed nitrate solution by adding hexamine, followed by heat treatment of the gel. The powder was characterized by XRD, TG, DTA and specific surface area measurement. Pellets were pressed and sintered to achieve densities up to 90% of theoretical density.

Processing and Sol Chemistry of a Triol‐Based Sol–Gel Route for Preparing Lead Zirconate Titanate Thin Films

A triol‐based sol–gel system has been developed for the fabrication of thin films of lead zirconate titanate (PZT). Starting reagents were lead acetate, zirconium and titanium isopropoxides, acetylacetone, and 1,1,1‐tris(hydroxymethyl)ethane (THOME), with 2‐methoxyethanol (MOE) being used to dilute the sols for spin coating purposes. Preliminary characterization by NMR spectroscopy suggested that the gels consisted of the metal ions and bound THOME, acetylacetonate, and acetate residues, with some possible M–O–M bridges. Uncracked 0.4 μm single‐layer PZT films of nominal composition PbZr0.53Ti0.47O3 were prepared on platinized substrates. Dielectric and ferroelectric properties were determined for samples made from sols containing 10 and 15 mol% excess lead acetate. Improved values were obtained for samples made from sols containing the higher excess; these exhibited a remanent polarization of 34 μC·cm−1, a coercive field of 54 kV·cm−1, and a relative permittivity of 1000.

Low-temperature preparation of hydrothermal lead zirconate titanate thin films

In preparing lead zirconate titanate thin films under hydrothermal conditions, we investigated the effects of concentrations of nutrient and mineralizer, reaction time and reaction temperature on crystallinity, grain size and shape. Experiments were performed in the ranges of 0.1-1.0M Pb(NO3)2, and 0-6.0M KOH with varying reaction time from 0 to 48 hours at 60-200 °C. In the experiment, lead zirconate titanate thin film of homogeneous crystalline grain was obtained through a 24 hour reaction with 0.4M Pb(NO3)2 and 5.0M KOH at 140 °C. The thickness of the film was 0.9-1.6 μm, and it exhibited a saturation polarization (Ps) of 18.3 μC/cm2, remnant polarization (Pr) of 7.4 μC/ cm2 and coercive field (Ec) of 0.41 kV/cm. The dielectric constant and loss (δ) measured at 1 kHz were approximately 1020 and 0.15, respectively.

Structural development in the early stages of annealing of sol–gel prepared lead zirconate titanate thin films

Lead zirconate titanate (PZT) thin films on platinized silicon were fabricated and their structural development upon annealing was characterized by x-ray diffraction and transmission electron microscopy (TEM). The amount of a transient intermetallic phase Pt3Pb was found initially to increase with annealing time and to decay after reaching a maximum. The kinetic process of growth and decay was simulated by using the Avrami equation. The Avrami coefficient n and growth rate constant k were determined by comparing the experimental results and the simulated curves, from which activation energies of 40 and 145 kJ/mol were obtained for the growth and decay of the intermetallic Pt3Pb phase, respectively. The perovskite PZT was found by using TEM to nucleate epitaxially on top of the Pt3Pb phase. Evidence is presented that the Pt3Pb phase plays a major role in determining the crystallite’s orientation at the nucleation stage of the perovskite PZT. This depends strongly on the annealing temperature and the orientation changes little during the following growth process.

Preparation of Lead Zirconate Titanate (Pb(Zr0.52Ti0.48)O3) by Homogeneous Precipitation and Calcination

Preparation of phase‐pure PZT (Pb(Zr0.52Ti0.48)O3) powders was achieved, in the presence of urea (CH4N2O), by homogeneous precipitation. Aqueous solutions of PbCl2, ZrOCl2·8H2O, and TiCl4 were used as the starting materials in the synthesis of phase‐pure PZT powders. Phase evolution behavior of precursor powders was studied by powder X‐ray diffraction (XRD) in air, over the temperature range of 90° to 750°C. The morphology of the formed powders was studied by scanning electron microscopy (SEM). Semiquantitative chemical analyses of the samples were performed by energy‐dispersive X‐ray spectroscopy (EDXS).

Lead zirconate titanate/poly(vinylidene fluoride-trifluoroethylene) 1-3 composites for ultrasonic transducer applications

A new procedure for preparing lead zirconate titanate (PZT)/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) 1-3 composites with both phases piezoelectrically active is described. Sintered PZT rods are inserted into a prepoled copolymer matrix, and the composite is repoled under a lower electric field. Using this new procedure, the dipoles in the two phases are aligned in either the same or opposite directions. Composite disks, of 12.7-cm diameter and 0.33- to 0.60-mm thicknesses, have been fabricated with PZT rods of 0.8 or 1 mm diameter distributed in a square pattern with 3 mm center-to-center separation. The ceramic volume contents of the composite disks are 3.6 and 5.6%, respectively. The resonance characteristics of the composite disks consist of the resonance modes of the two constituent phases, but they are dominated by the coupled longitudinal thickness mode (H-mode) of the PZT rods. The coupled radial mode (L-mode) resonance of the PZT rods is significant only for thin disks. The observed resonance frequencies of the H- and L-modes agree well with the values calculated from the coupling theory. The thickness mode resonance of the copolymer matrix (T-mode) is present but hardly observable in thick disks. The composite disks have been fabricated into transducers with air-backing and with no front face matching layer, and their performance characteristics have been evaluated in water. The transmitting and receiving voltage responses of a PZT/P(VDF-TrFE) composite transducer are better than those of a PZT/epoxy composite transducer. The transmitting and receiving voltage responses are improved when the PZT rods and copolymer matrix are poled in opposite directions, especially when the resonance frequencies of the H- and T-modes are approximately equal. When the phases are poled in the same direction and the resonance peaks associated with the Hand T-modes just overlap, the bandwidth is improved. Using 0.33-mm thick composite disks, a transducer can be produced with three operating frequencies by poling the constituent phases in the same direction, or with two operating frequencies at equal efficiency by poling the constituent phases in opposite directions. The PZT/P(VDF-TrFE) 1-3 composite transducer, especially the one with multiple operating frequencies, should be very promising in the applications of medical ultrasonic imaging.

Early stages of growth and nanostructure of Pb(Zr,Ti)O 3 thin films observed by atomic force microscopy

We prepared lead zirconate-titanate (PZT) layers with different thicknesses on Au coated Si(100) and Si(111) wafers by pulsed laser deposition, using the same set of experimental conditions: a Nd-YAG laser, 1064 nm, 10 ns, 10 Hz, substrate temperature 370°C, oxygen pressure 150 mTorr, laser fluence 25 J/cm 2, by varying the number of laser pulses. Different analysis put in evidence the crystallographic structure and chemical composition of films. Surface morphology was examined by atomic force microscopy (AFM). Analysis of films with very few atomic layers suggests that the growth proceeds by Volmer–Weber island-growth mechanism. Different geometrical, chemical and kinetic factors responsible for this type of growth are discussed. Comparative AFM analyses of surface roughness performed on films with different thickness allow for the study of the interface width evolution during the growth and to predict the conditions for obtaining films with a smooth surface.

Lead Zirconate Titanate Prepared from Different Zirconium and Titanium Precursors by Sol‐Gel

Modified sol‐gel processes have been developed for the preparation of lead zirconate titanate (PZT) (52/48) powders. These processes use different starting sources to introduce the titanium and zirconium components, namely tetraethyl orthotitanate, titanium isopropoxide, or titanium diisopropoxide bis(2,4‐pentanedionate) for titanium and zirconium propoxide or zirconium acetylacetonate for zirconium. To achieve stable and homogeneous precursor systems, several solvents (acetic acid, 1,2‐propanediol, propanol, and distilled water) and chemical modifying additives, such as acetylacetone and nitric acid, were also introduced for the preparation processes. The influence of the different precursors on the crystallization behavior of the sol‐gel‐derived powders was studied. Well‐crystallized single‐phase PZT powders were obtained after heat treatment at 600°C for 1 h. The powders obtained sintered well at 1000°C/2 h and a homogeneous microstructure with small grain sizes was obtained.

Investigation of the pyrolysis of lead zirconate titanate gels with coupled differential thermal analysis, thermogravimetry and infrared spectroscopy

The pyrolysis of organic components in the sol-gel preparation of lead zirconate titanate (PZT) from lead acetate and zirconium and titanium propanolate in methoxyethanol is studied with simultaneous differential thermal analysis, thermogravimetry and infrared spectroscopy. The first pyrolysis step of the dried PZT gel, yielding acetone and CO2 similar to the pyrolysis of lead acetate, indicates that most of the acetate groups are bonded to Pb2+. In the second step, the remaining organic components are oxidized to CO2 and H2O. The formation of undesired carbon residues during pyrolysis from unhydrolysed alkoxide groups and acetate groups bonded to Zr4+ and Ti4+ can be prevented by steam treatment of the dried gels. Activation energies for the different pyrolysis steps of lead, zirconium and titanyl acetate, lead decanoate and PZT gels are given. © 1998 Kluwer Academic Publishers

Extrusion and properties of lead zirconate titanate piezoelectric ceramics

The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investigated in comparision with different processing conditions. Finally, the measuremental results of density, dielectric and piezoelectric properties are reported and analyzed.

Seeding effects in the sol-gel preparation of lead zirconate titanate (PZT) powders

Lead zirconate titanate, Pb(Zr, Ti)O3 (PZT), crystallizes in a perovskite form from an intermediate pyrochlore phase and the effects of the presence of perovskite seeds have been considered. PZT powders have been obtained from lead acetate and Zr and Ti alkoxides using a sol-gel process involving a chemical modification by acetylacetone. Perovskite seeds have been introduced during the process by means of colloidal suspensions in acetylacetone. The seeding effects have been evidenced from DTA and XRD measurements, the formation temperature of pure perovskite phase being lowered by 50°C with 5 wt% seeds. More dense powder microstructure is observed in presence of seeds.

Preparation of lead zirconate titanate thin films by reactive magnetron co-sputtering

A reactive magnetron co-sputtering method with multiple metal targets was used to prepare lead zirconate titanate films, with Zr Ti ratios of 85 15 , 52 48 and 30 70 . The lead content was also varied. Films deposited on platinum coated silicon substrates followed by rapid thermal annealing crystallized in the perovskite structure at 600 °C and showed (100) preferred orientation. The effects of Pb content in the films and Zr Ti ratio on structural and electrical properties were investigated. Ti rich PZT films showed larger polarizations and higher coercive fields. Films which were nearly fatigue-free up to 10 [9] fatigue cycles have been prepared. Monitoring the operating voltage, current and power of the Pb target, and oxygen control during deposition were found to be important in the preparation of high quality PZT films.

Ferroelectric thin film microstructure development and related property enhancement

Abstract Factors that control phase evolution, microstructural development and ferroelectric domain assemblage are evaluated for chemically prepared lead zirconate titanate (PZT) thin films. Zirconium to titanium stoichiometry is shown to strongly influence microstructure. As Ti content increases, there is an apparent enhancement of the perovskite phase nucleation rate, grain size becomes smaller, and the amount of pyrochlore phase, if present, decreases. While the pyrochlore matrix microstructure for near morphotropic phase boundary composition thin films consists of two interpenetrating nanophases (pyrochlore and an amorphous phase); the pyrochlore microstructure for PZT 20/80 films deposited on MgO substrates is single phase and consists of 10 nm grains. Zirconium to titanium stoichiometry also has a substantial influence on process integration. Near morphotropic phase boundary films exhibit extensive reaction with underlying TiO2 diffusion barriers; conversely, there is no chemical reaction for identi...

Influence of platinum-based electrodes on the microstructure of sol-gel and MOD prepared lead zirconate titanate films

Abstract The microstructure and preferred orientation of PZT films deposited by spin-coating techniques are shown to depend on the morphology of the Ti/Pt bottom electrode. Annealing of the as-deposited Ti/Pt electrodes results in the formation of hillocks. These hillocks serve as nucleation sites for perovskite formation and thus determine the microstructure and preferred orientation of the crystallized PZT films. The microstructure features are investigated by X-ray diffraction analyses and scanning and transmission electron microscopies.

Microwave calcination of conventionally and sol-gel prepared lead zirconate titanate

Microwave calcining of conventionally prepared (mixed oxides) as well as sol-gel prepared lead zirconate titanate (PZT) powders was investigated. Conventionally prepared PZT was calcined with microwave power at 720°C for 45 min, whereas conventional calcination requires 4 h at 800°C. The sol-gel PZT was calcined with microwave power at 600°C for 40 min, whereas 5 h are needed when a conventional furnace is used at the same temperature. Beside reducing the calcining temperature and time, microwave heating also leads to a more uniform particle size distribution in both cases.

Metalloorganic solution deposition of ferroelectric PZT films

The metallo-organic solution deposition (MOSD or sol-gel) technique can be used for preparing lead zirconate titanate (PZT) ceramics with a wide range of compositions and crystal structures for electrooptical applications. Film morphology is affected by the stoichiometry of the film, hydrolysis and polymerization of the sol-gel solution, and thermal treatment of the deposited material. The lattice parameter decreases with the amount of titanium in the PZT, in agreement with ceramic data. A slight initial excess of lead in the coating solution is found to improve film morphology. Unlike traditional powder ceramic processing techniques, MOSD permits the growth of small uniform grains that are conducive to achieving consistent electronic and optical properties. Results show that the properties of films prepared by the MOSD process can be tailored to meet the needs of device applications.