Search

Pb-free (Ba0.88Ca0.12)(Ti0.94Sn0.06)O3 piezoelectric nanopowder was synthesized by solid-state reaction method. Piezoelectric properties were improved by two different approaches by optimizing poli...

Poling process is one of the widely used strategies to enhance the film properties during the manufacturing processes of ceramic film. A lab-made PbZrxTi1-xO3 (PZT) film by spin-coating on Ti substrate is presented. After heating treatments, the fabricated film was passed corona poling under ultraviolent (UV) light of various power. The characteristics of the PZT film have been evaluated by several instruments, such as X-ray diffractometer (XRD), scanning electron microscopy (SEM) and impedance analyzer. The results indicated that UV light would affect the orientation of crystallization, microstructure and grain size of PZT film surface during poling process under room temperature.

The effect of electrical (DC) contact poling processes on the ferroelectric and piezoelectric properties of sol–gel and pulsed laser-deposited PZT thin films has been investigated as a function of ...

We report enhancement of photovoltaic properties of highly oriented BiFeO3 (BFO) thin films. The single phase rhombohedral R3c space group structure was confirmed by XRD and Raman spectra in the films grown on SrTiO3 (111) substrates using RF magnetron sputtering. The films of BFO were characterized in planar geometry with top Pt electrodes having 200μm diameter, ∼40nm thickness and at a regular spacing of ∼150μm deposited by DC sputtering process. For photovoltaic studies the current voltage characteristic of as grown and poled samples were studied under the white light illumination having energy density of ∼1kW/m2. The as grown films showed open circuit voltage (Voc) of ∼3.9V which increased up to ∼17.8V on poling with 200V. This enhancement in Voc by poling was attributed to increase in net polarization due to alignment of domains in the direction of applied electric field and hence potential barriers between the domains.

Calculation of chromophore polar order, i.e. the polarization of nonlinear optically (NLO) active polymers poled by external field, is challenging. One possible solution is to reproduce the orientation polarization of chromophores under external field using Langevin dynamics (LD) molecular modeling. The present work investigates the influence of chromophore dipole moment, density and field extent on NLO efficiency and polarization/relaxation dynamics. Results of simulations convince us, that the method is applicable for modeling real NLO polymers. In the spotlight of this investigation we would like to describe a NLO polymer as a “ferrofluid” where chromophores are active particles or electrets.

The paper reports the influence of lanthanum substitution on the structural, dielectric and piezoelectric properties of PZT. Polycrystalline samples were synthesized by solid state reaction technique. XRD analysis shows all the samples to be single phase with perovskite structure, initially showing rhombohedral structure and then transforming into rhombohedral. The transition temperature (Tc) was observed to decrease monotonically with increasing x. The results showed that, after poling, the dielectric constant decreased for rhombohedral composition but increased for tetragonal compositions. Electromechanical coupling factor (kp) was found to increase with x and becomes saturate at x = 0.07 mol%. Composition with x = 0.07 gives maximum value of kp = 52% and d33 = 450 pC/N. All the samples depict well defined ferroelectric behavior.

Ferromagnetic/piezoelectric composites show strong magnetoelectric coupling that is mediated by mechanical forces. This work is on (i) synthesis of functionally-stepped ferrite-ferroelectric composites and (ii) investigations on the magneto-electric (ME) interactions. Studies were performed on sintered samples of nickel cobalt ferrite and lead zirconate titanate (PZT). The grading parameters of interest are the piezomagnetic coefficients, q, and the piezoelectric coefficients, d. The grading in q is accomplished by compositional variation and the grading in d by poling direction. Measurements of the ME coefficient revealed the strongest coupling in functionally graded samples and the weakest for bilayers with homogeneous q and d.

Sc-modified (0.3 mol%) multiferroic BiFeO3 thin films (BFS) were synthesized on Pt/Ti/SiO2/Si substrates through a chemical deposition method. The effect of Sc doping on the fatigue and retention properties, and polarization switching with magnetic poling of the films were investigated. Through Sc-doping, the film exhibited marked improvement in fatigue behavior at least up to 1011 cycles in comparison with the BFO film. The stable polarization retention property of the BSF film over the range of 1–105 seconds demonstrated that Sc doping in BFO improved the retention characteristics compared to BFO. This supports that Sc addition can reduce oxygen vacancies and charge defects in the BSF system which results in the excellent fatigue and retention properties. Magnetic field poling of 0.8T improved the polarization of the BSF film by about 48% which decreased slowly to ∼10% after 14 days. These results suggest that the BSF film has potential in ferroelectric and magnetic devices applications.

Polar scan and fixed points poling are applied in the domain switching of LiNbO3 crystal using scanning probe microscopy. The dependence of lifetime on initial switched domain size is investigated. The radius of visible switched domains is larger than the critical domain radius R C , which is used to distinguish whether the decay process of the switched domain is thermally activated or not. With the same initial radius, the lifetime of the domains switched by fixed points poling is larger than that by polar scan, which is determined by the different domain configurations.

Lead zirconate titanate [Pb(Zr0.52Ti0.48)O3, PZT] thin films were deposited on Pt (111)/Ti/SiO2/Si and Pt (200)/Ti/SiO2/Si substrates by sol-gel method. Pyrolysis temperature and time were used to control the orientation of the thin films. A PbO buffer layer was also used to enhance the growth of (100)/(001) orientation. Poling highly (100) oriented PZT 52/48 thin films deposited on Pt (111) led to cracking and/or incomplete poling as a consequence of the additional residual stresses introduced by the a to c domain orientation switching. These problems of cracking and incomplete poling did not occur for the (100)/(001)-oriented PZT films deposited on the Pt (200), which possess high piezoelectric coefficients with maximum e31,f and d33,f of −13.9± 4 C/m2 and ∼80± 25 pC/N, respectively. The elastic and electromechanical properties were measured using nanoindentation for films with different texture and compared with data obtained using a flexural method.

In this study, we attempted to examine the properties of La-substituted bismuth titanate (BLT) thin film utilizing piezoresponse force microscope (PFM). BLT thin films were made using two step rapid thermal annealing (RTA). Three BLT thin films with random crystallographic orientation were obtained by varying the RTA conditions. AFM images show that the BLT thin film consists of three distinct shapes of grains. Each grain revealed different piezoresponse according to their shapes. Therefore, we investigated the relationship between the shape of a grain and polarization orientation. In addition, we studied grain polarization by monitoring the difference between the initial PFM image and PFM image after poling using 3D PFM. It is very useful to understand the piezoresponse in terms of polarization. Furthermore, it provides information about the domain motion in the BLT thin film with random crystallographic orientation.

Pulse switching properties were studied in polycrystalline Pb(Zr,Ti)O3 capacitors to check a recently proposed nucleation limited switching (NLS) model, where very wide switching was observed. The backing-switching responses (P b) at the end of writing pulses were studied to understand the role of writing pulse together with switching polarization (Δ P). The P b+Δ P, with high enough write voltage, is almost independent of writing pulse width (t w), even though Δ P is observed to increase with increasing t w. From these results, it is concluded that the NLS dynamics are attributed to the switching and poling processes with external fields around coercive fields.

The polarization dependence of the Stokes photoluminescence (PL) spectra of erbium doped Potassium niobate (KNbO3) ceramics has been investigated by studying the relations between PL spectra with the poling electric field, poling time. All the Stark splitting components of 4S3/2→ 4I15/2 transition were evident after the poling process. The experiments also showed that the polarization enhances the fine structure and modifies the intensity ratio of the 4S3/2→ 4I15/2, 4F9/2 → 4I15/2 and the 4S3/2→4I13/2 transitions at different poling electric fields and poling times. From the similar tendency between the frequency shift of PL spectra Δv and the planar electromechanical coupling factor Kp demonstrate indirectly that the Stark splitting was produced by the dipole moment of erbium ions state interacting with the internal local electric field due to polarization.

Monolithic ceramics with an uniaxial gradient of piezoelectric and/or dielectric coefficients (functionally graded materials—FGM) are suitable for bending actuators with strongly reduced internal mechanical stresses. We prepared BaTi1—xSnxO3 ceramics with a Sn-content of 7.5 mol% (BTS7.5) at the upper side and 15 mol% (BTS15) at the lower side. Two sheets of powder with different stoichiometry were pressed and sintered. The gradient of stoichiometry was modified by additional layers of powder with 10 and 12.5 mol% Sn, respectively. The Sn content after sintering across the thickness was investigated by Electron Probe Micro-Analysis (EPMA). The gradient of the chemical composition was transformed into a functionally gradient of the electromechanical properties by a poling process. An increasing of the bending deflection was obtained by cycling with an unipolar AC-voltage. In this work we studied two effects which can explain this behavior.

The effect of processing on the ferroelectric and piezoelectric properties of sol-gel grown Pb1.1Nb0.04Zr0.2Ti0.8O3 (PNZT) thin films was investigated. The effective d 31 piezoelectric coefficient of as-grown films was measured using piezoelectrically actuated cantilevers. The results indicate that films annealed after each layer possess a significant internal field, leading to high piezoelectric coefficients in the as-grown PNZT films. But the films annealed in the final step possess a very small internal field, and, consequently, small piezoelectric response.

Thin films of poly(vinylidene fluoride-hexafluoropropylene) P(VDF-HFP) show significant electroactive properties, such as piezoelectricity, pyroelectricity and electrostriction. Suitable polar P(VDF-HFP) copolymer films can be prepared by melt-pressing or solution-casting. Dipolar orientation causes the macroscopic polarization and thus also the symmetry breaking necessary for electroactive properties. We discuss the polarization build-up in thin, stretched and non-stretched, films of P(VDF-HFP) copolymer with a HFP content of 15%. Poling currents measured in-situ during electric poling are analyzed and the polarization is calculated. Suitable electric poling leads to hysteresis phenomena of the polarization as a function of the electric field as well as to significant polarization during switching experiments. Our results indicate dipolar orientation also in non-stretched P(VDF-HFP) films. ∗Originally presented at 10th European Meeting on Ferroelectricity, Cambridge, UK, August 3–8, 2003.

We found the giant electromechanical coupling factor of k31 mode to be over 80% and the piezoelectric d31 constant to be nearly −1700 pC/N in ferroelectric single crystals of Pb[(Zn1/3Nb2/3)0.91 Ti0.09]O3 (PZNT91/09). The origin of the giant k31 was as follows: the crystal with multi-domains changed into one having a mono-domain in the direction perpendicular to the poling field (k31 mode) as well as in the direction parallel to the poling field. The discovery of the giant k31 found a key to clarify the origin of the high piezoelectricity in PZNT91/09. Investigating the crystal orientation dependence of k31 and their aging characteristics, the giant k31 and d31 accompanied with the superior aging characteristics could be obtained in the case of the rhombohedral (100) crystal poled along [001] of the original cubic direction. Furthermore, it is found that the Young's modulus Y (0.89×1010 N/m2) in rhombohedral PZNT91/09 with giant k31 is remarkably small. Therefore, we believe that the high piezoelectricity...

We quantitatively track in real-time, the changes in domain statistics with electric field poling, of a ferroelectric Bi 4 Ti 3 O 12 thin film using optical second harmonic generation as a probe. The ferroelectric hysteresis loop is extracted from these optical measurements using a theoretical model. The model also yields ratios of intrinsic nonlinear coefficients such as d 11 / d 12 = m 3.54 - 0.31, d 26 / d 11 = 0.4 - 0.03, and optical birefringence | n b m n a | = 0.079 - 0.015.

Thick-film composites with 5 % to 30 % volume fraction of nanocrystalline lead titanate (PT) ceramic particles dispersed in a 70/30 mol-% vinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] copolymer matrix were prepared by solution casting followed by compression moulding. The crystal structure of the PT particles and the microstructure of the composite were characterized by XRD and SEM, respectively. The composites were poled at elevated temperature to produce samples with only the ceramic phase polarized. The poling current was recorded during the poling process, and a roughly exponential decay has been observed with "time constants" in the order of 10 3 s. The pyroelectric coefficient has been studied as a function of poling time. The built-up of the pyroelectric coefficient is faster than the decay of the poling current. Among composites with different ceramic loading the polarization develops with a higher rate in the composites with higher ceramic volume fraction. The polarization profiles of the p...

Electrical properties of 1- w m-thickness preferentially -oriented PZT ferroelectric films of rhombohedral composition near the morphotropic boundary prepared by RF magnetron sputtering of a ceramic target containing additionally 10 mol % lead oxide were studied. The data obtained suggests n -type conductivity due to lead oxide excess in the films. Such films were characterized by combination of a self-polarization and migratory polarization. It was shown that the self-polarization - thickness distribution was nonuniform with the most poled state localized near the bottom interface of the thin ferroelectric capacitor. The mechanism, which lies in base of such self-polarization, is related to the electron charging of the bottom interface of the structure during cooling after the high-temperature crystallization of the PZT film in the absence of the top electrode, and to bulk poling of the film by the charged interface. Heat treatment of such capacitor led to elimination of self-polarization. The obtai...

A linear pyroelectric sensor array with calcium and lanthanum modified lead titanate/vinyli-dene fluoride-trifluoroethylene, [PCLT/P(VDF /TrFE)] composite film as the sensing material was fabricated and tested. The composite film contained 30 volume % of PCLT powder particles. A two-step poling procedure was used to polarize both the ceramic and copolymer phases in order to enhance the pyroelectric coefficient. The pyroelectric and dielectric properties of the PCLT/P(VDF/TrFE) composite film were studied as a function of temperature. The signal from the sensor array was processed by amplifying transistors with multiplexing circuitry, which was mounted alongside the array on the same IC carrier. The current and voltage responsivities were measured over a frequency range of 10 Hz to 4 kHz and found to agree with the predictions based on a one-dimensional heat diffusion model. The noise of the sensor array with the associated electronics decreases with increasing frequency and is dominated by the fl...

The growth and characterisation of sol-gel lead zirconate titanate (PZT) (30/70) thin Films on indium tin oxide (ITO) coated glass have been investigated using X-my diffraction (XRD). transmitting electron microscopy (TEM) and atomic force microscopy (AFM). Perovskite crystallized at 550 degreesC in a random orientation. and all films showed characteristic rosette formations. A seeding and crystallisation model has been proposed to describe the rosette formation process. which is based on the ease of PbO diffusion through the film. The effect of drying temperature on annealed film properties has been examined and when optimised has been shown to improve electrical properties and film fatness. incorporation of the PZT Films into small prototype liquid crystal displays has been done. Application of pulsed poling voltages to the displays has resulted in bulk alignment of the liquid crystal adjacent to poled regions of the PZT layer which remained after the poling voltages were removed.

We report the measurements of pulse polarizations of (Pb, La)(Zr, Ti)O3 ferroelectric capacitors as a function of pulse width. Pulse polarizations were measured from the switching current responses in the pulse width range from 1 μs to 1 s. The relation between pulse polarizations(switched(P∗) and non-switched polarization(P⁁)) and hysteresis loop parameters was studied. In the case of all write/read pulse widths are same, P∗ increased but P⁁ decreased with increasing pulse width. These results are explained by poling effects and confirmed by measuring pulse width dependencies with different patterns of pulse trains.

Ferroelectric properties of metal/ferroelectric/metal capacitors can be severely degraded during FRAM® integration in a hydrogen containing ambient. To understand the mechanism of hydrogen damage we characterized ferroelectric capacitors with the configuration of Pt/PLZT/Pt and Pt/SBTN/Pt annealed in the temperature range of 50°C to 200°C using hysteresis and DC pulsing. The capacitors were stored in specific remanent states (negative, positive, and zero) by poling prior to annealing. The annealing was carried out in a forming gas ambient, containing 1% hydrogen and 99% nitrogen. The degradation is strongly dependent on the polarity of the remanent polarization. From the results, we propose an empirical model of the formation of a fixed dipole layer at the top electrode-ferroelectric interface and we confirm that the polarity of this charge is positive.

Although there are many studies for the characterization of piezoelectric thin film, it is still strongly needed to develop the easy and practical way to measure the piezoelectricity existing in thin film. Piezoelectric properties of lead zirconate titanate (PZT) thin film were investigated by a new pneumatic loading method, which has been devised as a more reliable and convenient characterization technique. We have observed the aging phenomena and have examined the effects of poling voltage and time on piezoelectric properties of the PZT thin films. There was no built-in piezoelectricity in virgin films.

Effective transverse piezoelectric coefficient e31,f has been measured on (100)/(001) sol-gel Pb(ZrxTi1−x) thin films with compositions between 30% and 45% Zr. A maximum value of 8.07 ± 0.36 C/m2 at 40% Zr is found. The influence of the poling field ranging from 50kV/cm to 250 kV/cm has been evaluated.

We investigate the imprint phenomenon by poling ferroelectric PLZT capacitors into a known state and exposing the devices to elevated temperatures. It is found that the compensation of oxygen vacancies is a important process parameter in determining the tendency to imprint. In the case of PLZT thin films, the voltage shifts related to imprint failure are attributed to the trapping electrons at defect sites near film/electrode interface, the magnitude of polarization and concentration of defect-dipole complexes involving oxygen vacancies such as V″Pb - V″o. The thermally induced voltage shifts in PLZT thin films are dopant concentration dependent and decrease with increasing the La concentration of the films.

An RF planar magnetron sputtering equipment with three cathodes was used to fabricate Zr-rich PZT thin films on PLT/Pt/Ti/SiO2/Si substrates using a multi-target. The multi-target consisted of PbO and metal titanate pellets on a zirconium metal plate. The optimum sputtering conditions were a gas content of Ar:O2 = 8:2 Sccm, gas pressure of 5 × 10×3 Torr, RF power of 100 W and substrate temperatures of 630–660°C. Polycrystalline Zr-rich PZT thin films have been successfully grown onto platinum film substrates, although the crystal structures of films were sensitive to the substrate temperature. The temperature dependence of the dielectric constant, tan δ and pyroelectric current of the PZT films were measured. Significant peak for the pyroelectric current was observed at the transition temperature of about 90°C from a low temperature to high temperature rhombohedral ferroelectric phases in as-grown PZT films without a poling treatment. Therefore, Zr-rich PZT films sputtered on PLT/Pt/Ti/SiO2/Si su...

Lead-based ferroelectric thin films, PT and PZT, have been deposited on platinized silicon substrates by using rf magnetron sputtering technique. Whatever the deposition network, the piezoelectric character has been demonstrated for all films. The piezoelectric response dependence of the poling treatment with the time and the applied dc electric field has been studied. The in-situ deposited films, without previous poling, present piezoelectric activity e31PT=-0.49 C/m2. The post-annealed films have a slight piezoelectric activity without poling treatment and maximum values of the piezoelectric coefficients have been obtained, e31PT=-0.41 C/m2 and e31PZT=-3.84 C/m2 with dc electric field of 100 and 150 kV/cm respectively. The piezoelectric responses are directly related to the structure of the films, they are discussed in terms of domain orientation during the films formation and during the poling treatment.

The switching process in tetragonal PZT films is studied. The ferroelectric capacitors show rectangular P-E hystersis loops with very abrupt switching characteristics. Small signal impedance measurements as function of DC bias voltage reveal an abrupt drop of the parallel capacitance C near the switching field EC, coinciding with a sharp peak of the equivalent parallel conductance G, different from the more gradual variation of C and G with broad peaks near EC as typically observed in materials with MPB composition. This behavior is correlated to strong 180° switching in this tetragonal material. This is further corroborated by the effects of the film orientation and of electrical and stress poling.

A planar multi target sputtering approach was used to deposit self polarized PZT films on TiO2/Pt bottom electrodes for the use in thin film pyroelectric IR detector arrays. By using elevated substrate temperatures of about 450°C “in situ” growth of tetragonal PZT could be achieved. The films exhibited pyroelectric currents without poling. The pyroelectric coefficient was 2×10−4 C/m2K, the dielectric constant was 300 and dielectric loss tan δ was 0.01. The self polarization disappears after heating the sample to 600°C. Stresses were studied in the thin film processing for the bottom electrode and the PZT film. The TiO2/Pt electrode is under high tensile stress of 900 MPa after preparation. PZT has a small compressive stress of -60 MPa, the whole TiO2/Pt/PZT stack has a tensile stress of +80 MPa. This low stress level together with the self polarization and the good electrical properties makes the films suitable for the use in pyroelectric detector arrays.

Zr-rich PZT and La-doped PT films were fabricated on a PLT/Pt/Ti/SiO2/Si or Pt/Ti/SiO2/Si substrate by an RF planar magnetron sputtering equipment using powder targets with compositions of PbZr0 94Ti0.06O3, PbZr0.92Ti0.08O3 and Pb0.85La0.15 Ti0.96O3 with excess PbO of 20 mol%. The dielectric constants of PZT and PLT films showed anomalies at the transition temperatures of around 246 and 300°C, and their dielectric constants at room temperature were 350 and 1070, respectively. Significant pytroelectric currents were observed in both as-grown PZT and PLT films even without a poling treatment. The pyroelectric coefficients of those films were 10 and 30 nC/cm2K, respectively. Therefore, Zr-rich PZT and [111]-oriented PLT films sputtered on Pt/Ti/SiO2/Si substrates possess desirable properties for potential applications to pyroelectric devices.

Ferroelectric polycrystalline Lanthanum lead zirconate titanate (abbreviated to PLZT) thin films with perovskite structure were prepared by hydrothermal method. Ferroelectric polycrystalline PLZT thin films with perovskite structure on titanium substrate were obtained at 180°C for 5 hr. The film thickness was easily controlled by repeating hydrothermal method. The densities of the PLZT thin films measured by Archimedes’ method were lower than those of ceramics. We fabricated bimorph-type bending actuators using these thin films and analyzed the displacement induced by the electric field. The actuators were bent by applied voltage without poling, because the polar axis in the as-deposited these thin films were aligned in the direction from the thin films surface to the substrate. The dielectric constant of these films were about 600 at room temperature for 1 kHz.

High sensitive pyroelectric infrared (IR) sensors have been fabricated by using c-axis oriented La-modified PbTiO3 (Pb1–xLaxTi1−x/4O3, PLT) thin films. The PLT thin films were deposited on (100)-cleaved MgO single crystal substrates by intermittent rf-magnetron sputtering method. The PLT thin films have high figures of merit for IR sensor without a poling treatment. High performance pyroelectric IR sensors (single element type and linear array type) were fabricated by using PLT (x=0·1, γ=5·5x10−8 C/cm2K, ϵr=200) thin films. The sensors have remarkably high D* of 3–6x108 cmHz1/2/W and very fast response. A new compact IR sensing system using the linear array sensor (8 elements) has been developed for a new type of room air-conditioner. This system can measure thermal distribution (8x64) by horizontal scanning of the vertical linear array. Image processing with neural network concept makes possible high-accuracy using a few data from the sensor elements. This sensing system provides ‘‘smart aircond...

Comparison has been made between the microstructures and electrical properties of Pb0·95La0·05TiO3 (PLT) thin films deposited on bare (100)MgO and on Pt/(100)MgO. Nearly perfect epitaxial PLT was grown on (100)MgO. (100)-oriented Pt film was obtained via coalescence of Pt islands formed on MgO. Highly c-axis oriented PLT thin film was successfully grown on the Pt bottom electrode with an electrically conductive network structure. High detectivity of 3·5 × 108 and 2·6 × 108 cm√Hz/W was obtained at 30 Hz without any poling treatments from the PLT/MgO- and PLT/Pt/MgO-based infrared detectors, respectively.

0–3 composites of lead zirconate titanate (PZT) and P(VDF-TrFE) (piezoelectric copolymer of polyvinylidene fluoride and trifluoroethylene) with different volume fraction of piezoelectric ceramic we...

Though many technical barriers must be crossed, current trends in materials fabrication suggest several routes to integrating electrooptic and nonlinear optical materials monolithically with silicon and III-V semiconductor technology. These approaches include poled organic polymers, poled fused silica, and polycrystalline or epitaxially grown dielectric and ferroelectric oxide thin films. Optical waveguides fabricated from these materials may enable applications in integrated optics such as frequency doublers and modulators. Although the principal work in our laboratory is on oxide heterostructures on GaAs and sapphire, the introduction highlights the progress of other approaches. Because optical losses limit the feasibility of many device structures, considerable discussion is devoted to this topic. The use of atomic force microscopy to predict scattering losses. The summary is preceeded by some brief remarks about poling.

Very thin films of lead zirconate titanate (PZT) (40/60), 0.26 μ or less, have been prepared on Pt-coated oxidized Si substrates (Pt/Ti/SiO2Si) by a sol-gel process. These films were of high density with fine grains of about 0.2 μm and annealed in the range of 600° to 700°C in oxygen atmosphere. X-ray diffraction patterns taken on this film showed single-phase perovskite-type structure. Pyroelectric and P-E hysteresis curve measurements, as well as measurements of the dielectric constant and loss tangent versus temperature and frequency, were performed. The influence of poling treatment on the dielectric and pyroelectric properties was also investigated, as well as dielectric constants and pyroelectric properties. Dielectric constants and pyroelectric coefficients at room temperature were determined as 1300 and 840, and 68.0 and 10.3 nC/cm2. °C for the poled and unpoled PZT films, respectively. The remanent polarization was 37.8 μC/cm2, and a coercive field was 146 kV/cm at a switching voltage of...

The deposition of single phase perovskite lead titanate thin films by planar multi-target sputtering on silicon substrates covered with a thin Pt bottom electrode has been investigated. The films exhibited nearly random crystallographic orientation. The films are self polarized, that means they exhibited pyroelectric currents without poling treatment. After additional furnace annealing and poling the pyroelectric coefficient was 1.7.10−4 C/m2K. The annealing also reduced the dielectric loss tan δ from 0.05 to 0.01. The temperature measurement for calculation of the pyroelectric coefficient was performed by measuring the resistance of the bottom and top electrode via the van der Pauw method and calibration with a thermo chuck.

We used the Scanning Nearfield Acoustic Microscope-a nontouching profilometer with a conducting tip-both to pole thin ferroelectric VDF-TrFE copolymer films and to subsequently monitor the resulting pie-zoelectrically stimulated surface motion. For thin uncovered polymer films we were able to measure simultaneously the piezoactivity and the surface topography with a lateral resolution of 1 μm. Furthermore we used a focused electron beam to create a poling pattern of narrow lateral extension and detected the corresponding local piezoactivity by using the Scanning Nearfield Acoustic Microscope.

We have carried out fatigue, aging and retention studies of epitaxial ferroelectric PbZr0.2Ti0.8O3/YBa2Cu3O7 heterostructures, grown by pulsed laser deposition. The capacitors show fatigue lifetime of better than 1010 cycles. We find that the fatigue process is reversible by the application of a 2 second “pulsed poling” treatment at the fatigue voltage. These results suggest that the loss of switchable polarization with cycling is due to domain wall pinning; however, the role of space charge effects at the electrodefilm interfaces cannot be ruled out. Indeed, the overall fatigue performance may be controlled by a combination of these two factors. These heterostructures show excellent resistance to aging (extrapolated lifetime of better than 1011 seconds and good logic state retention characteristics (1011 seconds).