Fabrication and Electrical Properties of Lead Zirconate Titanate Thick Films on Si Substrate by Using Lanthanum Nickelate Buffer Layer

Lead zirconate titanate PbZr_0.53Ti_0.47O₃ (PZT) thick films have been deposited on silicon substrate by modified metallorganic decomposition process. Crack-free PZT films of 8 μm thickness can be obtained by using lanthanum nickelate LaNiO₃ (LNO) as buffer layer. The greater LNO thickness, the greater thickness of crack-free PZT can be obtained. The X-ray diffraction measurements show the films exhibit a single perovskite phase with (110) preferred orientation. SEM measurements showed the PZT thick films have a columnar structure with grain size about 60–200 nm. The thickness dependence of ferroelectric, dielectric, and piezoelectric properties of PZT thick films have been characterized over the thickness range of 1–8 μm. For PZT with thickness of 8 μm, P _r and E _c are 30 μC/cm² and 35 kV/cm, and dielectric constant and dielectric loss are 1030 and 0.031, respectively. The piezoelectric coefficient ( d ₃₃) of PZT with 8 μm thickness is obtained to be 77 pm/V. PZT thick films on LNO-coated Si substrate are potential for MEMS applications.     

Processing and Properties of Screen-Printed Lead Zirconate Titanate Piezoelectric Thick Films on Electroded Silicon

The printing of lead zirconate titanate (PZT, Pb(Zr,Ti)O₃) piezoelectric thick films on silicon substrates is being studied for potential use as microactuators, microsensors, and microtransducers. A fundamental challenge in the fabrication of useful PZT thick-film devices on silicon is to sinter the PZT to high density at sufficiently low temperature to avoid mechanical or chemical degradation of the silicon substrate. The goal of the present study is to develop and implement suitable electrodes and PZT sintering aids that yield attractive piezoelectric properties for devices while minimizing reactions between the silicon, the bottom electrode, and the PZT thick film. A B₂O₃-Bi₂O₃-CdO sintering aid has been found to be superior to borosilicate glass, and the use of a gold/platinum bilayer bottom electrode has resulted in better thermal stability of the electrode/film structure. Films sintered at 900°C for 1 h have relative permittivity of 970 (at 1 kHz), remnant polarization of 20 μC/cm², coercive field of 30 kV/cm, and weak-field piezoelectric coefficient d ₃₃ of 110 pm/V.     

Synthesis of Lead Zirconate Titanate Stannate Antiferroelectric Thick Films by Sol-Gel Processing

The effects of different sintering procedures on the preparation of antiferroelectric thick films and the structure–property relations in these films were studied. An acetic acid-based sol–gel processing with multistep annealing and suitable lead oxide overcoat layers was developed to fabricate both niobium-doped and lanthanum-doped lead zirconate titanate stannate antiferroelectric thick films. The 5-μm-thick Pb_0.99Nb_0.02(Zr_0.85Sn_0.13Ti_0.02)_0.98O₃ films demonstrate typical square hysteresis loops with a maximum polarization of 40 μC/cm², zero remanent polarization, an antiferroelectric-to-ferroelectric phase transition field of 153 kV/cm, and a ferroelectric-to-antiferroelectric phase transition field of 97 kV/cm. The dielectric constant and dielectric loss are 283 and 1.7%, respectively. The 5-μm-thick Pb_0.97La_0.02(Zr_0.65Sn_0.31Ti_0.04)O₃ films display typical slanted hysteresis loops with very small hysteresis, a maximum polarization of 35.0 μC/cm², and zero remanent polarization. The dielectric constant and dielectric loss are 434 and 2.0%, respectively.     

Photonic Sintering of Aerosol Jet Printed Lead Zirconate Titanate (PZT) Thick Films

Lead Zirconate Titanate (PZT) is a commonly used piezoelectric material due to its high piezoelectric response. We demonstrate a new method of printing and sintering micro‐scale PZT films with low substrate temperature increase. Self‐prepared PZT ink was Aerosol‐Jet printed on stainless steel substrates. After drying for 2 h in vacuum at 200°C, the printed PZT films were divided into two groups. The first group was traditionally sintered, using a thermal process at 1000°C for 1 h in an Argon environment. The second group was photonically sintered using repetitive sub‐msec pulses of high intensity broad spectrum light in an atmospheric environment. The highest measured substrate temperature during photonic sintering was 170.7°C, enabling processing on low melting point substrates. Ferroelectric measurements were performed with a low‐frequency sinusoidal signal. The remanent polarization (P_r) and coercive field (E_c) for thermally sintered PZT film were 17.1 μC/cm² and 6.3 kV/cm, respectively. The photonically sintered film had 32.4 μC/cm² P_r and 6.7 kV/cm E_c. After poling the samples with 20 kV/cm electric field for 2 h at 150°C, the piezoelectric voltage constant (g₃₃) was measured for the two film groups yielding ?16.9 × 10^?3 (V·m)·N^?1 (thermally sintered) and ?17.9 × 10^?3 (V·m)·N^?1 (photonically sintered). Both factors indicate the PZT films were successfully sintered using both methods, with the photonically sintered material exhibiting superior electrical properties. To further validate photonic sintering of PZT on low melting point substrates, the process and measurements were repeated using a polyethylene terephthalate (PET) substrate. The measured P_r and E_c were 23.1 μC/cm² and 5.1 kV/cm, respectively. The g₃₃ was ?17.3 × 10^?3 (V·m)·N^?1. Photonic sintering of thick film PZT directly on low melting point substrates eliminates the need for complex layer transfer processes often associated with flexible PZT transducers.     

组成对锆钛酸铅铁电薄膜电性能影响的研究进展

锆钛酸铅材料因具有优异的介电、压电和铁电性被广泛用于制作电容器、压电器件和铁电随机存储器等功能器件.本文综述了锆钛酸铅铁电薄膜材料中锆钛比、掺杂种类及掺量对其介电性和铁电性的影响,并提出了亟待解决的问题.     

Ferroelastic Properties of Lead Zirconate Titanate Ceramics

To increase the reliability of multilayer actuators, calculation of the mechanical stress inside the device during operation is important. This paper shows that the small-signal value of the elastic constant s is not sufficient to describe the complicated behavior of lead zirconate titanate (PZT) ceramics. Therefore, compressive strain and depolarization have been measured as a function of large-signal stress applied parallel to the poling direction. The nonlinear dependence of the strain and depolarization can clearly be explained by domain processes. Soft and hard PZT ceramics have been investigated. In hard PZT, domain switching appears at higher stresses than in soft PZT. Moreover, in hard PZT, the domains partly switch back during unloading. The critical stress (coercive stress) necessary for a domain-switching process shows a dependence on the Zr:Ti ratio that is quite similar to the dependence of the electric coercive field. The influence of an electric field applied parallel to the poling direction and superimposed on the compression experiment also has been examined. The coercive stress depends linearly on the electric field. The linear coefficient of this relation is given by the ratio of depolarization to compressive strain caused by domain switching.     

Effects of Thickness on Piezoelectric Properties of Highly Oriented Lead Zirconate Titanate Films

Lead zirconate titanate (PZT) films were deposited on platinized silicon substrates by spin coating using PZT sols containing polyvinylpyrrolidone (PVP) as an additive. PZT films with a 60/40 composition and a thickness of up to 8 μm were fabricated by repeating the deposition process 15 times on highly oriented (100) and (111) seed layers with the same composition. The films grew well in the direction of the seed layers and had a uniform and smooth surface without any cracks. As the thickness of the films increased, the grain size remained almost the same, but the effective d ₃₃ value increased steadily. The thickness dependence of the piezoelectric properties was attributed to the residual stress of the films.     

Fabrication, Sinterability, and Mechanical Properties of Lead Zirconate Titanate/Silver Composites

High-toughness and high-strength lead zirconate titanate (PZT) composites that contain fine silver particles were successfully fabricated at low sintering temperatures. Addition of silver to a PZT matrix did not result in unwanted reaction phases; however, some silver diffused toward the perovskite crystal structure. A small quantity of silver accelerated the sinterability of the PZT composites. The formation of oxygen vacancies due to the partial substitution of silver appeared to enhance the sinterability of the PZT. Fracture toughness depended on the size and degree of sphericity of the silver particles, and SEM observations on crack propagation suggested that the toughening mechanism in the PZT/Ag composites involves crack bridging resulting from the ductile behavior of silver particles. It is proposed that high fracture strength in PZT/1 to 5 vol% Ag composites results from the relaxation of transformation-induced internal stress by the silver particles.     

Piezoelectric Properties of Ink‐Jet–Printed Lead Zirconate Titanate Thick Films Confirmed by Piezoresponse Force Microscopy

An ink consisting of Pb(Zr_0.53Ti_0.47)O₃ (PZT) particles with a median size of 170 nm and a narrow size distribution, in a dispersion of water and glycerol, and with a low viscosity and surface tension, was used for the fabrication of thick films by piezoelectric ink‐jet printing. This study reports the printing conditions, the subsequent thermal treatment of the as‐deposited layers, and the properties of the sintered PZT thick film. The film, sintered at 1100°C, had a locally dense microstructure and consisted of grains that are a few 100 nm across, as revealed by scanning electron microscopy. A local piezoelectric response of 15 pm/V was measured in the ink‐jet–printed PZT thick film by piezoresponse force microscopy.     

Longitudinal Electrooptic Effects and Photosensitivities of Lead Zirconate Titanate Thin Films

The feasibility of storing and reading high-density optical information in lead zirconate titanate (PZT) and in lead lanthanum zirconate titanate (PLZT) thin films depends on both the longitudinal electrooptic coefficients and the photosensitivities of the films. This paper describes the methods used to measure the longitudinal electrooptic effects and the photosensitivities of the films. The results of these measurements were used to evaluate a longitudinal quadratic electrooptic R coefficient, a longitudinal linear electrooptic r_c coefficient, and the wavelength dependence of the photosensitivity of a composition of PZT polycrystalline thin film. The longitudinal electrooptic R and r_c coefficients are about an order of magnitude less than the transverse R and r_c coefficients of bulk ceramics of similar compositions. This is attributed to clamping of the film by the rigid substrate. The large birefringence of the films after poling (>10⁻²) suggests that the optic axes of the films are preferentially oriented normal to the film surface. The techniques used in this paper for evaluating the photosensitivities of thin films are based on measuring the photocurrent generated rather than the reduction in coercive voltage (as in bulk ceramics) when the film is exposed to light. The thin film photosensitivities appear to be significantly higher than those of bulk ceramics of similar compositions. The high photosensitivities coupled with the substantial longitudinal electrooptic coefficients combine to establish the feasibility of using PZT or PLZT thin films for optical information storage applications.     

Low-Temperature Preparation of Nanocrystalline Lead Zirconate Titanate and Lead Lanthanum Zirconate Titanate Powders Using Triethanolamine

Nanocrystalline lead zirconate titanate (PZT) powders, with a Zr:Ti ratio of 60:40, have been prepared from a solution of triethanolamine (TEA) and Ti⁴⁺, Zr⁴⁺, and Pb²⁺ ions. The metal ions were in solution through complex formation with TEA. The soluble metal-ion–TEA complex formed the precursor material when it was completely dehydrated. Heat treatment of the precursor at 450°C resulted in single-phase PZT powders. The precursor and the heat-treated powders have been characterized by using thermal analysis and X-ray diffractometry (XRD) studies. The average particle size, as measured from X-ray line broadening and transmission electron microscopy studies, was ∼20 nm. PZT powders modified with 3 mol% of lanthanum (PLZT) also were prepared through this route and were investigated via XRD studies. The dielectric constants of the PZT and PLZT powders were 12475 and 11262, and their corresponding Curie temperatures were 362° and 315°C, respectively.     

Effect of Compositional Variations in the Lead Lanthanum Zirconate Stannate Titanate System on Electrical Properties

The purpose of this work was to evaluate the effect of compositional modifications on the electrical properties of lead lanthanum zirconate stannate titanate (PLZST) ceramics, as well as to examine their electrically induced phasechange behavior. Variations in the Ti:Sn ratio were evaluated. Increased Ti⁴⁺ content produced the following: decreased switching field, related to an increased antiferro-electric-ferroelectric (AFE-FE) transition temperature; constant hysteresis (Δ E ) correlated with a constant temperature of the maximum dielectric constant (T_max); a sharper dielectric-constant maximum peak; and increased room-temperature dielectric constant ( K ). Variations in the Zr:Sn ratio also were evaluated. Increased Zr⁴⁺ content produced the following: increased hysteresis with increased T_max , decreased maximum dielectric constant, and decreased switching field with increased AFE-FE transition temperature (T_AFE__FE). From these results, with respect to compositional modifications, the AFE-FE switching field (E_AFE__FE) and Δ E were observed to be dependent strongly on T_AFE__FE and T_max, respectively. Negligible change existed in the strain achievable at the switching field, which remained constant for all compositions at ∼0.16%. The significance of this research was the ability demonstrated to tailor the properties of phase-change materials through compositional modifications.     

Effect of Lead Zirconate Titanate Seeds on PtxPb Formation during the Pyrolysis of Lead Zirconate Titanate Thin Films

Lead zirconate titanate (PZT) thin films were prepared on platinized silicon substrates by dip-coating using a modified diol-based sol–gel route without and with up to 5 mol% PZT nanometric seeds dispersed in the precursor sol. A metastable intermetallic Pt _x Pb phase formed at the early stages of heat treatment. XRD, TEM, and RBS revealed that the thickness and stoichiometry of the Pt _x Pb layer varied with the concentration of seeds and heat treatment of the films. The relation of the Pt _x Pb layer to the final crystalline texture of the PZT thin films is reported and discussed.     

Properties of Lead Zirconate Titanate Thin Films Prepared Using a Triol Sol–Gel Route

Microstructure and phase development during the thermal decomposition of sol–gel precursor coatings of PbZr_0.53Ti_0.47O₃ on platinized silicon substrates have been investigated for a triol sol–gel route. The single-layer, 0.4 μm PZT films were heated from below the substrate, over the temperature range 350–600°C, using a calibrated hot plate. The first crystalline phase to appear was a PbPt₃ intermetallic phase at the Pt/PZT interface. Although perovskite PZT formed at ca. 500°C, heating at higher temperatures, for example 550°C for 30 min, was required to develop ferroelectric hysteresis loops. However, the rather low value of remanent polarization, P _r= 11 μC·cm⁻², was consistent with incomplete crystallization at 550°C. The values of remanent polarization increased with increasing processing temperatures, reaching 21 μC·cm⁻² for samples heated at 600°C, with a corresponding E _c value of 57 kV·cm⁻¹. Distinctive spherical precipitates up to ca. 50 nm in size have been identified by TEM in the lower portions of otherwise amorphous coatings, after heating at around 350–400°C. Although their precise composition could not be identified, they were mostly Pb-rich, and it is speculated that they form due to reduction of some of the lead(II) acetate starting reagent, to atomic Pb during the early stages of thermal decomposition of the organic components of the gel; it is possible that subsequent reactions occur to form lead oxides or carbonates. High levels of porosity were present in many of the fully crystallized films. The possible reasons for this are discussed.     

钽镁酸钡缓冲层对锆钛酸铅铁电薄膜性能的影响

采用溶胶–凝胶工艺在Pt/Ti/Si O2/Si基片上,通过引入钽镁酸钡[Ba(Mg1/3Ta2/3)O3,BMT]缓冲层,制备了锆钛酸铅[Pb(Zr0.52Ti0.48)O3,PZT]铁电薄膜。研究了BMT缓冲层对PZT铁电薄膜结晶和性能的影响。结果表明:引入BMT缓冲层利于PZT薄膜的生长;PZT薄膜具有钙钛矿结构,且没有裂纹、结晶良好、致密性好;缓冲层的厚度对PZT铁电薄膜的微观结构和铁电性能有重要影响。随BMT缓冲层厚度增加,PZT晶粒增大,介电损耗tanδ逐渐减少,介电常数εr和剩余极化强度Pr先增大后减少,矫顽场Ec先减少后增大。当BMT缓冲层厚约为10 nm时,PZT薄膜具有最优的铁电性能:εr=1 850,Pr=20.2μC/cm2,Ec=43.9 k V/mm。这与BMT与PZT具有相似的晶格常数、较小的晶格失配度和相近的禁带宽度有关。     

Microstructure of Solution-Processed Lead Zirconate Titanate (PZT) Thin Films

Lead zirconate titanate (PZT) thin films with a composition near the morphotropic phase boundary (Zr/Ti = 53/47) were fabricated by spin deposition of an alkoxide-derived solution and annealed at 650°C for 30 min. A complex microstructure is observed in which micrometer-scale rosettes of the desired perovskite phase are surrounded by nanocrystalline (10 to 15 nm) grains of pyrochlore structure. Transmission electron microscopy (TEM) demonstrates that the perovskite rosettes—features of approximately circular cross section which grow rapidly within the confined conditions of the thin film—are single crystals despite being highly porous. Pockets of lead-deficient pyrochlore extend throughout the thickness of the film. The only effects of Nb (2%) doping on the microstructure are to increase the fraction of the perovskite phase and the perovskite grain size. Despite the highly irregular shape of the perovskite particles and the presence of some pyrochlore, reasonable ferroelectric properties are measured (spontaneous polarization P _s∼ 0.2 C/m²).     

锆钛酸铅纳米粉体的凝胶燃烧法制备及表征

以偏钛酸、双氧水、氨水、乙酸铅和硝酸锆为原料,乙二胺四乙酸(ethylene diamine tetraacetic acid,EDTA)为络合剂,柠檬酸为燃烧剂,采用凝胶燃烧法制备得到了锆钛酸铅(PbZr0.52Ti048O3,PZT)纳米粉体.首先,按相同摩尔比将偏钛酸溶于双氧水和氨水的混合溶液中,再加入适量的柠檬...     

Lead Zirconate Titanate Hollow-Sphere Transducers

Millimeter-sized, hollow spheres of lead zirconate titanate were fabricated by blowing gas through a fine-grained slurry of PZT-5. After they were sintered, the spheres were poled in two ways: radially between inside and outside electrodes, and tangentially between two outside electrodes. The capacitance and vibration modes were modeled and measured for these two poling configurations. The two principal modes of vibration were a breathing mode near 700 kHz and a wall thickness mode near 10 MHz. These spheres have potential uses in medical ultrasound, nondestructive testing, and low-density transducer arrays.     

Angularly and Spectrally Resolved Light Scattering from Lead Zirconate Titanate Thin Films

The results of light-scattering measurements of a series of Pb(Zr,Ti)O₃ thin films prepared by a sol-gel method are presented and analyzed. The films differed due to the addition of different concentrations of acetylacetone to the precursor solution immediately prior to film fabrication. Visual inspection of the films indicated improvements in optical quality with the addition of acetylacetone. To quantify these improvements, two types of light-scattering measurements were performed: angularly resolved light scattering and spectrally resolved light scattering. Surprisingly, only slight differences between the films were observed using angularly resolved light scattering at 633 nm. In contrast, the spectrally resolved scattering revealed large differences between the films, with the films prepared using the largest concentrations of acetylacetone exhibiting the lowest scattering. The apparent contradiction between these findings is resolved using a theoretical model for light scattering due to fluctuations in the dielectric constant occurring within the volume of the thin film and by noting that slight thickness differences exist between the films in the series. Analysis of the light scattering from the best sample yields estimates for the amplitude (ζ₀= 0.08) and the characteristic size (T₀= 110 nm) of the dielectric constant fluctuations. These estimates are consistent with the variations of the dielectric constant expected due to the birefringent, polycrystalline nature of these films.     

Phase Stability and Ferroelectric Properties of Lead Strontium Zirconate Titanate Ceramics

The effect of compositional modifications on the field-induced phase-transition behavior and dielectric properties of strontium-doped lead zirconate titanate (PZT) ceramics was studied. PZT compositions with different strontium and titanium contents, within the general formula Pb_{1– x} Sr _x (Zr_{1– y} Ti _y )O₃ and located in the tetragonal antiferroelectric (AFE) and rhombohedral ferroelectric (FE) phase fields were prepared by tape casting and sintering. X-ray diffraction and polarization measurements were used to locate compositions suitable for investigation of the field-induced AFE–FE phase transition. The results indicated that a higher Sr²⁺ content decreased the polarization and hysteresis and increased the switching field; a lower Ti⁴⁺ content decreased the polarization and increased the switching field and hysteresis. A high room-temperature dielectric constant was obtained for compositions near the phase boundary. These results suggest that a combination of both A -site and B -site modifications can be used to tailor ferroelectric properties, such as the switching field and hysteresis, of these strontium-doped PZTs displaying a field-induced AFE–FE phase transition.