Preparation Of Lead Zirconate Titanate Research Articles

Large aspect ratio microscale 1–3 piezoelectric arrays prepared by soft mold combined with UV curing

1-3 piezoelectric composites, as materials with integrated structural/functional characteristics, are typically used to manufacture ultrasonic transducers. As a core sensitive element, the structural dimensions as well as the molding quality of the 1–3 piezoelectric array, will directly affect the transducer's operating performance. In this paper, an improved soft mold process is proposed to prepare lead zirconate titanate (PZT) microscale 1–3 piezoelectric arrays by a soft mold combined with UV curing process. Firstly, the rheological behavior of PZT ceramic suspension and the preparation process of polydimethylsiloxane (PDMS) soft mold were studied. The surface contact angle of the Si master mold modified by trimethylchlorosilane (TMCS) was significantly increased, facilitating the peeling of the PDMS soft mold from the Si master mold surface, thus improving the surface quality of the PDMS soft mold. Then, the sintering process, microstructure, and electrical properties of microscale 1–3 piezoelectric arrays were systematically investigated. The perpendicularity and integrity of the piezoelectric arrays were improved by an optimized sintering process, and the arrays had micropillar diameters as small as 8 μm and aspect ratios over 7.5. The electrical properties of the piezoelectric composites with thicknesses of 55 μm and 42 μm were analyzed to obtain their resonant frequencies fs of 33.8 MHz and 41.3 MHz, respectively. The developed novel soft mold process can realize the preparation of microscale 1–3 piezoelectric arrays with fine structure and large aspect ratios, which are expected to fabricate high-frequency ultrasonic transducers.

3D printing of lead zirconate titanate piezoelectric ceramics via digital light processing (DLP)

Research of piezoelectric ceramics via DLP technology has drawn considerable interest due to its high geometrical flexibility. However, the poor curing properties limit the use of DLP technology to fabricate piezoelectric ceramics. Herein, we overcome this challenge in prepared lead zirconate titanate (PZT) piezoelectric ceramics via DLP technology by incorporating ultralow refractive index and ultraviolet light absorptivity of soluble starch in PZT ceramic slurry. After the post-process, the relative density of printed PZT ceramic with 20 vol% soluble starch could reach about 89.51% of theoretical density. The printed PZT ceramic exhibits remarkable dielectric permittivity, remnant polarization, piezoelectric strain constant, piezoelectric voltage constant, figure of merit and electromechanical coupling factor of 2196, 35.56 μC/cm2, 373 pC/N, 1.92 × 10−2 Vm/N, 7.16 × 10−12 m2/N and 42.28%, respectively. The results achieved in this research indicate that our work provides a promising route for fabrication of advanced ceramics with high performance and designed complex structures by digital light processing.

Novel fabrication of PZT thick films by an oil-bath based hydrothermal method

Abstract This paper introduces an innovative way to prepare lead zirconate titanate thick films near the morphotropic phase boundary using oil-bath based hydrothermal method with magnetic stirring. Undergoing once nucleation process and four-time crystallization process, approximately 10 µm PZT thick films could be obtained. This PZT film performed good ferroelectric and dielectric property. At room temperature, the coercive field (E c ) and the remnant polarization (P r ) were 37.5 kV/cm and 7 μC/cm 2 , respectively. In the frequency range between 1 kHz to 1 MHz, dielectric constant decreased from 300 to 250 and the dielectric loss was below 0.1. These promising results suggest that the oil-bath based hydrothermal method is a good candidate for PZT film fabrication.

Improvement of the fatigue and the ferroelectric properties of PZT films through a LSCO seed layer

The ability to optimizate the preparation of Lead Zirconate Titanate (PZT) films on platinized Si substrate by pulsed laser deposition was demonstrated. The effect of the modification of the interface film/electrode through the use of a (La,Sr)CoO3 (LSCO) seed layer on the remnant polarization, fatigue endurance and stress in PZT films was studied. An improvement on the ferroelectric properties was found with the using of the LSCO layer. A remnant polarization (Pr) of 19.8 μC/cm2 and 4.4 μC/cm2 for films with and without the LSCO layer were found. In the same way the polarization fatigue decreases significantly after deposition of the LSCO layer between the film and substrate. Atomic force microscopy (AFM) images revealed a different growth process in the films. Current–voltage (I–V) measurements showed that the use of LSCO seed layer improves the leakage current and, on the other hand the conduction mechanisms in the film without LSCO, after the fatigue test, was found to be changed from Schottky to Poole–Frenkel. The trap activation energy (about 0.14 eV) determined from Poole–Frenkel mode agrees well with the energy level of oxygen vacancies. The films stresses were estimated by XRD in order to explain the improvement on the structure and consequentially ferroelectric properties of the films. The model proposed by Dawber and Scott was found to be in agreement with our experimental data, which seems to predict that the oxygen vacancies play an important role on fatigue.

Sol-hydrothermal synthesis and characterization of lead zirconate titanate fine particles

A novel sol-hydrothermal route to prepare lead zirconate titanate (PZT) fine particles is presented, which combined the conventional sol–gel process and the hydrothermal method. The effects of experimental parameters including sol/(sol+water) ratio, reaction temperature and reaction time on the product powders were investigated. The prepared PZT powders were characterized by XRD, SEM/EDS, and Raman techniques. The results indicated that the optimal synthesis conditions were sol/(sol+water) = 20%, 200°C, 8h. The obtained powders with an average particle size of 700nm, were phase pure perovskite PZT with cubic-shaped morphology, and the reaction temperature was as low as 150°C, which was comparatively lower than that synthesized by the normal sol–gel route. It was supposed that the sol precursor and hydrothermal environment played important roles in the formation of the PZT fine powders at low temperature and low mineralizer concentration.

Mist Deposited Lead Zirconate Titanate Films

The liquid source misted chemical deposition (LSMCD) method was employed in the preparation of lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 (PZT) thin films. The desired thickness of the films was adjusted by a number of successive deposition/heating cycles. Typically, a 500-nm-thick film was achieved by running four processing cycles. The PZT films showed good phase purity with a (111)-preferred crystallographic orientation. The capacitance voltage (C-V) and polarization electric field (P-E) hysteresis curves displayed normal ferroelectric behavior of LSMCD-derived films with asymmetric switching. The dielectric and ferroelectric properties were comparable with the properties of thin films prepared by other techniques.

Roles of polymeric dispersant charge density on lead zirconate titanate aqueous processing

Poly(acrylic acid) (PAA) and poly(acrylic acid- co-maleic acid) (PACM) were used as dispersants in preparation of lead zirconate titanate (PZT) aqueous suspensions. The effects of dispersant structure on particle stabilization were investigated through properties of the suspensions. Viscosity and sedimentation height measurements showed that addition of the dispersants improved particle stabilization. The dispersant concentrations to obtain the lowest viscosity were 0.4 wt% for PAA and 0.2 wt% for PACM based on powder dried weight basis. Furthermore, effects of pH were studied on the suspensions prepared with 0.2 wt% dispersants. Viscosity and sedimentation behaviors indicated the improvements of particle dispersion and suspension stability with an increasing pH. Particle dispersion revealed by laser light scattering and scanning electron microscopy supported an improvement of particle dispersion at alkaline pHs. Detailed analysis of these data indicated that the PACM exhibited higher dispersant efficiency for PZT aqueous suspension in all conditions. The results were discussed based on the concentrations of anionic –COO − groups at various pHs and charge density along polymeric backbone of the dispersants.

Molten salt synthesis of PZT powder for direct write inks

The preparation of lead zirconate titanate (PZT) powder by molten salt synthesis (MSS) is described and a mechanism proposed. The effect of process parameters, such as reaction time and temperature and heating rate, on particle size and shape was investigated. A reaction mechanism for the synthesis of PZT by molten salt method is proposed, where dissolved Pb initially reacts with insoluble TiO 2 to form intermediate PbTiO 3. Subsequently Zr diffuses into and reacts with PbTiO 3 to form PZT. Spherical particles, ∼340 nm in size, were obtained, using a NaCl/KCl salt, by heating the starting materials at 850 °C for 60 min, with a ramp rate of 3.3 °C min −1.

PZT thin film preparation by pulsed DC magnetron sputtering

Pulsed DC magnetron sputtering was used in this study to prepare lead zirconate titanate (Pb(Zr x Ti 1− x )O 3, PZT) thin films. A single metallic target was used for the deposition onto a Pt/Ti/SiO 2/Si substrate and parameters such as: pulse frequency, duty cycle, O 2/Ar flow ratio controlled so as to analyze the effect of the parameters on thin film deposition rate, crystalline structure and morphology. After the deposition, the thin film was annealed in a rapid thermal annealing (RTA) furnace. The experimental results showed that, when the pulse frequency was in the range of 10 kHz–100 kHz, along with the lowering of frequency and the oxygen argon flow rate ratio, the deposition rate gradually increased and the formation of PZT thin film perovskite phase was enhanced; however, if the oxygen argon flow rate ratio was too high, it caused the PZT thin film to generate a pyrochlore phase. However, when the duty cycle was in the range of 95%–75%, the highest deposition rate and better perovskite phase could be obtained in the range of 75%–80%.

Active Modulation of Surface Plasmon Resonance Wavelengths by Applying an Electric Field to Gold Nanoparticle-Embedded Ferroelectric Films

In this study, we use organic chemical addition and phase-transfer methods to prepare lead zirconate titanate (PZT) composite films embed with large numbers of gold nanoparticles (Au NPs). The surface plasmon resonance (SPR) wavelength in the nanocomposite materials can be modulated cyclically through the application of an external electric field. The Au NPs are embedded homogeneously in the PZT matrix; the PZT crystal size and the metal particle size both increase upon increasing the annealing temperature. The Au/PZT nanocomposite film displays apparent piezoelectric properties in its ferroelectric hysteresis curve that can be used in the active modulation of the SPR wavelengths. The major factor influencing the shift in the SPR absorption in the Au/PZT nanocomposite films is the change in the refractive index of the host PZT matrix.

Preparation of ferroelectric PZT thin films by plasma enhanced chemical vapor deposition using metalorganic precursors

The low temperature and non-thermal equilibrium process is the major advantage of plasma enhanced chemical vapor deposition (PECVD) method for thin film deposition. In this study, the preparation of lead zirconate titanate (PZT) thin films by PECVD has been evaluated. As-deposited PZT thin films prepared via PECVD with Pb(C 2H 5) 4, Ti(O- i-C 3H 7) 4 and Zr(O- i-C 4H 9) 4 source had an amorphous phase and transformed into a crystalline structure from the annealing temperature of around 500 °C under an oxygen ambient. Change of Pb content in the film did not occur under a wide range of annealing temperatures and times, but the surface morphology became coarser with an increase of Pb content. The dielectric constant was strongly affected by the PZT film thickness. Typically the dielectric constant of PZT (Zr/Ti = 54/46) film was 572 at a thickness of 240 nm. Additionally, the film had a remnant polarization, 2 P r,of 42 μC/cm 2 and a coercive filed, E r, of 88 kV/cm.

Infrared spectroscopic study of microwave-sintered Pb(Zr,Ti)O3-based ceramics

Infrared spectroscopy is often used to monitor the formation of the perovskite phase during the preparation of lead zirconate titanate (PZT) thin films and fibres and also to detect phase transitions. Infrared spectroscopy has rarely been used to investigate bulk samples or thick films of PZT. In this study, the first results of infrared investigations of microwave-sintered PZT and PZT reinforced with powdered copper are presented and compared with results from thermally heated samples. The infrared spectra show the typical Zr/TiO(6) metal-oxygen octahedral vibrational modes in the range 750 to 450 cm(-1). This band is broadened for the pure PZT samples at higher sintering temperatures. A shift of the peak to lower wave numbers with increasing temperatures can be proven for pure PZT samples, but not for the Cu-reinforced PZT samples.

Preparation and characterization of PZT solid solutions via sol–gel process

The present research describes a modified sol–gel process that has been developed for the preparation of lead zirconate titanate (PZT) (0.52/0.48) powders. In this route, diethanolamine (DEA) was used as a complexing agent to keep the metal ions in homogeneous solutions without undergoing precipitation. Drying treatment led to development of transparent gel network. Phase-pure perovskite structure was formed at 500 °C. The crystallization behavior of the sol–gel-derived powders was studied by X-ray diffraction (XRD) and simultaneous thermal analysis. Differences between the sequence of phase formation encountered in the traditional (oxide-mix) synthesis and that in chemically derived lead zirconate titanate ceramics are discussed.

Piezoelectric PZT films for MEMS and their characterization by interferometry

Piezoelectric films can be used in micro-electromechanical system (MEMS) devices because the piezoelectric effect can provide high forces with relatively low energy losses. The energy output by a piezoelectric film per unit area is proportional to the film thickness, so it is desirable to have relatively thick films. Chemical solution deposition (CSD) techniques were used to prepare lead zirconate titanate (PZT) thin films with Zr/Ti ratios of 30/70 and 52/48. Usually CSD processing is restricted to making crack-free single layer films of ca 70 nm thick, but modifications to the sol-gel process have permitted the fabrication of dense, crack-free single layers up to 200-300 nm thick, which can be built-up into layers up to 3 μm thick. Thicker PZT films (>2 μm single layer) can be produced by using a composite sol-gel/ceramic process. Knowledge of the electro-active properties of these materials is essential for modeling and design of novel MEMS devices and accurate measurement of these properties is by no means straightforward. A novel double beam common path laser interferometer has been developed to measure the piezoelectric coefficient in films and the results were compared with the values obtained by Berlincourt method. A laser scanning vibrometer was also used to measuring the longitudinal (d 33 ) and transverse (d 31 ) piezoelectric coefficients for PZT films and ceramics and the results were compared to those obtained by the other methods. It was found that for thin film samples, the d 33,f values obtained from the Belincourt method is usually larger than those obtained from the interferometer method but smaller than those from the vibrometer method and the reasons for this are discussed.

Effect of Thickness on Microstructure and Electrical Properties of PZT Films Prepared by a Modified Sol-Gel Method

A modified sol-gel multiple coating and annealing process was developed to prepare lead zirconate titanate PbZr 0.5 Ti 0.5 O 3 (PZT) thin films with various thickness on Pt(111)/Ti/SiO 2 /Si(100) substrates. The PZT films with thickness 280, 560 and 810 nm underwent one, two and three annealing cycles, respectively, which consisted of 5 coating layers, 10 coating layers and 15 coating layers. Surface morphology and phase structure of the thin films were studied by SEM and XRD, respectively. The relationship between the thickness, namely different annealing cycles, and degree of texture was investigated. The dielectric constant increases with increasing film thickness. The dielectric constant and dielectric loss of PZT films as functions of applied field and frequency had also been examined and discussed.

Effect of porosity on the ferroelectric properties of sol–gel prepared lead zirconate titanate thin films

Pb(Zr 0.3Ti 0.7)O 3 (PZT) thin films are of major interest in micro-electro-mechanical systems for their ability to provide electro-mechanical coupling and pyroelectric coupling. In this work, dense, crack-free PZT thin films have been obtained on silicon substrates up to a thickness of 3 μm. Piezoelectric coefficients d 33,f and e 31,f of sol–gel processed films were investigated as a function of film thickness. Both d 33,f (− 50∼− 90 pC/N ) and e 31,f (2.5∼4 C/m 2 ) values have been obtained in the whole thickness range of 1–3 μm. Increasing the thickness of a single layer introduced pores into the films. Up to 700 nm porous, crack-free single layers could be obtained. It was found that the introduction of pores into the thin films decreased the dielectric constant. Therefore, it helps increase the pyroelectric performance. A dense PZT thin film (700 nm) has dielectric constant, F d and F v of 372, 1.02 × 10 − 5 Pa − 0.5 and 0.022 m 2/C, respectively, while a porous thin film (700 nm) with porosity of 3% has dielectric constant, F d and F v of 210, 1.32 × 10 − 5 Pa − 0.5 and 0.031 m 2/C, respectively.

Preparation of lead zirconate titanate thin films with a combination of self-assembly and spin-coating techniques

A low-temperature synthetic method for preparing lead zirconate titanate (PZT) perovskite film on a Pt substrate is proposed. The method consists of the self-assembly of PZT particles on a substrate and successive spin coating with a precursor of PZT. The PZT particles that had sub-micron sizes and perovskite structures were prepared by annealing amorphous PZT particles formed from a complex alkoxide precursor. The PZT particles were deposited on a Pt substrate that was surface-modified with (3-mercaptopropyl) trimethoxysilane to chemically fix the particles on the substrate. Another PZT precursor solution was used for the spin-coating on the PZT-deposited substrate, and then the spin-coated film was annealed at 350 °C to remove organic residues left in the film. The spin-coated PZT film prepared at 350 °C had a dielectric constant of 118 at a frequency of 1000 Hz.

Sol-Gel Synthesis of Nanocrystalline PZT Using a Novel System

A simple system has been developed for the preparation of lead zirconate titanate, Pb(Zr x Ti1 − x)O3 powders by sol-gel process. To achieve stable and homogeneous precursor solutions, chelating ligands such as acetic acid and acetylacetone have been used for the chemical modification of titanium and zirconium starting precursors. Phase-pure PZT powders were obtained, through a pyrochlore-free pathway, from the amorphous xerogel after heat treatment at 600°C. The formation of the crystalline phase, compositional homogeneity, sinterability, dielectric and piezoelectric characteristics of PZT are reported.

Effects of poly(ethylene glycol) additive molecular weight on the microstructure and properties of sol-gel-derived lead zirconate titanate thin films

Poly(ethylene glycol) (PEG) additives with different molecular weights were used to modify sol-gel precursor solutions for preparing lead zirconate titanate (PZT) thin films. The morphology, crystalline structure, and mechanical and electrical properties of the films were characterized. The relationship between the characteristics of the films and the molecular weight of PEG was investigated. It was observed that the PEG eliminated cracking of the films during multiple pyrolysis treatments. However, with the increase of the PEG molecular weight, the films became less dense, which led to decreased Young's modulus and dielectric constant and increased coercive field. Our experiments showed that films prepared from sols modified by PEG with a molecular weight of 200 exhibited a dense morphology and excellent mechanical and electric properties without cracking.

Determination of optimal experimental conditions for the preparation of lead zirconate titanate via sol-precipitate process by applying statistical methods

A fractional factorial design was implemented to optimize the experimental conditions for the preparation of lead zirconate titanate (PZT) from acetate precursors. The effects of such preparatory conditions as the molar ratio of acetic acid to metal alkoxide, the water to alkoxide ratio, the pH value, reaction temperature and the stirring speed, were systematically studied by using a Taguchi orthogonal array design. Results indicated that the molar ratio of acetic acid to metal alkoxides and the reaction temperature were the key variables influencing the average particle size of the powders obtained. By combining the optimal setting of these two influential processing variables, a fine powder with a particle size of ≈2200 Å was obtained. Fourier transfer infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were used to investigate the effects of the chelation on the rate of formation of the precursor and PZT powder. The rates of hydrolysis and polycondensation of the acetate precursors were slow because of the chelation of a high ratio of acetic acid with the alkoxide. The particle size of the obtained PZT powder was small and a homogeneous distribution resulted.