Zirconate Titanate Thin Films Research Articles

THD improvement of piezoelectric MEMS speakers by dual cantilever units with well-designed resonant frequencies

In this study, a piezoelectric MEMS (Micro-Electro-Mechanical-System) speaker with thoughtfully selected resonant frequencies of dual cantilever units is designed and implemented. Based on the lead zirconium titanate (PZT) thin film with superior piezoelectric coefficient, the cantilever diaphragm is designed through the modal analysis. In the 1.5 mm by 1.5 mm cantilever array, a high-frequency actuation unit with resonance of 13.1 kHz and a low-frequency actuation unit with resonance of 6.35 kHz constitute the proposed piezoelectric MEMS speaker. The boost of sound pressure level (SPL) due to the resonant mode of low-frequency actuation unit reduces the total harmonic distortion (THD) around the subharmonic frequency of high-frequency actuation unit. Meanwhile, the asymmetric triangle diaphragm reduces the maximum stress in the structure when operating at the resonant frequency, thereby mitigating the THD spikes resulting from the nonlinear structural behavior. In pressure-field measurements, the proposed design can reach SPL ≥ 70.0 dB from 2.7 kHz to 15.0 kHz with only 0.179 Vrms input. At the same time, THD remains below 3.0 % from 3.2 kHz to 20 kHz. The outstanding performance under larger input signal and bias voltage is also verified. Actuated by 0.354 Vrms and 2 VDC bias, the maximum SPL achieves 111.9 dB and the SPL is higher than 80.0 dB from 3.3 kHz to 14.1 kHz. Furthermore, THD is lower than 3.0 % from 1.0 kHz to 8.9 kHz. A promising solution of piezoelectric MEMS speaker for in-ear applications is demonstrated in this study.

PZT based dual energy harvester using chemical solution deposition technique

The present finding reports the state-of-art thin film based dual energy harvester which can harvest both mechanical as well as magnetic energies. Dual energy harvester is realised with the help of Lead Zirconium Titanate (PZT) thin film and nickel (Ni) foil. Ferroelectric PZT has been grown with the help of chemical solution deposition technique under optimised conditions on Nickel cantilevers. The effect of damping mass on the resonating frequency of the PZT-60/Ni dual cantilever has been studied. The maximum power and voltage generated by dual energy harvester at the matching load impedance of 100 kΩ under resonance condition were about 117 × 102 mW/m3 and 52 mV respectively corresponding to an applied acceleration of 1.0 g. A change of about 0.5 mV/Oe voltage was achieved for PZT-60/Ni cantilever in the presence of magnetic field. The dual energy harvester prepared with the help of chemical solution technique is found to have profound response and hence enables the realization of self powered electronic devices by scavenging an ambient magnetic and mechanical energies for various wireless electronic applications ranging from medical implant to health monitoring areas.

Synthesis and Analysis of Zirconium Titanate Thin Films by using Sol-Gel Method

Titanium-doped zirconium oxide (mixed high-k) has been used as the gate oxide layer for the future generation metal oxide semiconductor devices. This mixed high-k layer was prepared by using Sol-Gel based spin-coated method. This mixed high-k layer’s chemical, structural, and initial electrical properties are investigated thoroughly. It is clearly confirmed that the suitable chemical composition and bond formation of the proposed mixed high-k layer from EDAX and FTIR analysis observations. The XRD spectra strengthened the presence of ZrTiO2. The measured dielectric constant of the proposed mixed high-k layer from the extracted C-V plots has been varying from 29.1 to 37.6 with respect to spin coating from 4000 to 6000 rpm. With lower spin rates, the leakage current is less.

Investigation of the effects of rapid thermal annealing on the structural properties of lead zirconate-titanate thin films

The purpose of this work is to study the effect of rapid thermal annealing (RTA) with halogen lamps on the structural and phase characteristics of lead zirconate-titanate (PZT) films. The PZT thin films with a thickness of 1.0 ± 0.1 μm were deposited by high-frequency reactive plasma sputtering in an oxygen atmosphere on oxidized silicon and silicon substrates with orientation (100). After deposition, the PZT films subjected to RTA at temperatures of 500 °C, 600 °C and 700 °C at a rate of 60 °C/s. The structural-phase composition of PZT films was determined with X-ray diffraction analysis. Studies of heterostructures with scanning electron microscopy methods have shown that increase in the temperature of the RTA leads to a qualitative change in the structural-phase state of the PZT film as compared to its initial state. This makes it possible effectively using of RTA in the formation of PZT films with specified parameters.

Diphenylalanine-Derivative Peptide Assemblies with Increased Aromaticity Exhibit Metal-like Rigidity and High Piezoelectricity.

Diphenylalanine (FF) represents the simplest peptide building block that self-assembles into ordered nanostructures with interesting physical properties. Among self-assembled peptide structures, FF nanotubes display notable stiffness and piezoelectric parameters (Young’s modulus = 19–27 GPa, strain coefficient d33 = 18 pC/N). Yet, inorganic alternatives remain the major materials of choice for many applications due to higher stiffness and piezoelectricity. Here, aiming to broaden the applications of the FF motif in materials chemistry, we designed three phenyl-rich dipeptides based on the β,β-diphenyl-Ala-OH (Dip) unit: Dip-Dip, cyclo-Dip-Dip, and tert-butyloxycarbonyl (Boc)-Dip-Dip. The doubled number of aromatic groups per unit, compared to FF, produced a dense aromatic zipper network with a dramatically improved Young’s modulus of ∼70 GPa, which is comparable to aluminum. The piezoelectric strain coefficient d33 of ∼73 pC/N of such assembly exceeds that of poled polyvinylidene-fluoride (PVDF) polymers and compares well to that of lead zirconium titanate (PZT) thin films and ribbons. The rationally designed π–π assemblies show a voltage coefficient of 2–3 Vm/N, an order of magnitude higher than PVDF, improved thermal stability up to 360 °C (∼60 °C higher than FF), and useful photoluminescence with wide-range excitation-dependent emission in the visible region. Our data demonstrate that aromatic groups improve the rigidity and piezoelectricity of organic self-assembled materials for numerous applications.

Preparation of PZT Thin Film/Ni Particle Composite Magnetoelectric Materials

Lead Zirconium Titanate (PZT) thin film magnetoelectric materials have widely application in controllable sensing and tuneable microwave devices. The PZT film ferroelectric domain was designingly distributed and reversed by using the piezoelectric power response technique. The magnetoelectric composite of PZT film and Ni particle was prepared by the ferroelectric spontaneous polarization separation photogenerated carrier, reduction Ni atom deposition on the PZT thin film ferroelectric positive domain region. The optical morphology, XRD and SEM morphology show that the Ni particles deposited on the PZT film increase first and then become more uniform with the extension of deposition time. The deposition time closely relate to the deposition effect of Ni particles, and the deposition effect is more obvious with time. After the photo-deposition, the surface particles of the unexcited domain film are scattered after the photo-deposition, and the shape of the deposited particles region in which the Ni particles are reduced is substantially similar to the write-domain pattern, and the particle diameter is about 10-20 nm.

A facile solution-combustion-synthetic approach enabling low-temperature PZT thin-films

A low-temperature (≤450 °C) crystallization path for the solution-derived lead zirconium titanate (PZT) thin-film, the first choice for high-density ferroelectric/piezoelectric nanodevices, has been sought for long but with limited success. In this work, we report on a facile route enabling the crystallization of PZT thin-films at 300–450 °C by using a novel solution-combustion-synthetic (SCS) approach. The SCS precursor solution consists of metal nitrates and organic fuels (tricine and/or urea) as oxidizing and reducing agents, respectively. The essential aspect of this route is that the single and intense exothermic combustion reaction between the oxidizer and fuels occurring at 234 °C provides high self-localized thermal energy, which allows for the efficient conversion of the amorphous metal-oxide gel framework into final crystallized oxides even at very low externally applied temperature. Effects of annealing conditions such as temperature and time are systematically investigated. At optimized conditions, high-quality PZT thin-films are achieved with pure perovskite phase, large remanent polarization (∼37 µC/cm2), and small leakage current (∼0.1 µA/cm2 at 600 kV/cm). Furthermore, an application of the developed low-temperature PZT film for the ferroelectric-gate memory transistor is demonstrated. The potential integration of low-temperature processed PZT layers with other active components may redefine the design concept of classical nano-microelectronic devices.

Dielectric and optical properties of zirconium titanate thin films by reactive DC magnetron co-sputtering

Zirconium titanate thin films were deposited on alumina substrates by DC magnetron reactive co-sputtering by varying substrate temperature and the effects of substrate temperature on optical and dielectric properties of the films have been studied intensively by available characterization techniques. The optical parameters were determined by Swanepoel's method. The films exhibited high transmittance in the visible region and the optical band gap of the films varied from 3.1 to 2.8 eV as the temperature varied from 33 to 400°C. The film deposited at room temperature exhibit a high transmittance of 71%. Dielectric constant measurements have been carried out at 10 GHz of frequency. The dielectric constant increased with increase in temperature and the film deposited at 400oC exhibited a high dielectric constant (40) and a low dielectric loss (0.026).

Ferroelectric Barium Zirconate Titanate Films on Sapphire Substrates

The structural and electrical physical properties of barium titanate zirconate thin films on pure sapphire substrates and sapphire substrates with a platinum sublayer are investigated. The nature of substrate is shown to have a considerable effect on the crystal structure, phase composition, and electrical parameters of the prepared thin films. Capacitive elements fabricated using barium zirconate titanate films display high nonlinearity at low dielectric losses, as measured at a frequency of 2 GHz.

Effects of the ‘spring structure’ on the performance of a vibrating plate of the piezoelectric inkjet print-head

One of the core components of piezoelectric inkjet print-head is the piezoelectric vibrating plate which directly affects the jet performance of a print-head. In the present paper, a simplified coupling model theory of the composite vibrating plate was studied in combination with the actual manufacturing process of the piezoelectric vibrating plate. The ‘spring structure’ is formed by releasing the long edge of Lead Zirconate Titanate (PZT) thin films to enhance the amplitude of the piezoelectric vibrating plate. The laser Doppler measurement was carried out on the piezoelectric vibrating plate, and the results were verified by using numerical simulation. The results show that the ‘spring structure’ can effectively improve the amplitude and average deformation rate of the piezoelectric vibration plate in the air while does not affect the deformation time. The amplitude of the vibrating plate with spring structure increased continuously in the dwelling stage of the drive signal when the ink was inspired. Moreover, the magnitude of residual vibration also increased.

High frequency Coplanar Microwave Resonator using ferroelectric thin film for Wireless Communication Applications

In the present work, the electrical properties of Lead Zirconium Titanate (PZT) thin film have been investigated for the realization of microwave resonators. The PZT thin film deposited using pulsed laser deposition technique (PLD) has been exploited as dielectric layer for the tunable resonators for the widespread applications in the field of communication. The polycrystalline thin film of PZT shows good dielectric and tunable properties. The dielectric constant and dielectric loss of the PZT thin film deposited at 800°C substrate temperature were found to be 390 and 0.08. A microwave resonator has been fabricated using the optimized PZT thin film at a resonating frequency of 12.02 GHz which is in microwave range.

Сегнетоэлектрические пленки титаната-цирконата бария на сапфировых подложках

AbstractThe structural and electrical physical properties of barium titanate zirconate thin films on pure sapphire substrates and sapphire substrates with a platinum sublayer are investigated. The nature of substrate is shown to have a considerable effect on the crystal structure, phase composition, and electrical parameters of the prepared thin films. Capacitive elements fabricated using barium zirconate titanate films display high nonlinearity at low dielectric losses, as measured at a frequency of 2 GHz.

Characterization of Lead Zirconium Titanate thin films based multifunctional energy harvesters

The present work focuses on the fabrication of Lead Zirconium Titanate (PZT) thin film based multifunctional energy harvester for power generation using mechanical vibrations and magnetic energy. To realize the harvesters, single phase PZT thin films are deposited using pulsed laser deposition (PLD) technique under different growth conditions on the surface of cantilevers of Ni metal (PZT/Ni). The harvester having optimized PZT thin film exhibits a relatively high value of induced voltage of 5.9mV when subjected to mechanical vibrations of 1g acceleration. The same system (PZT/Ni), results in an induced voltage of about 1.53mV on application of 1.6×10−4T direct current (DC) magnetic field superimposed with 1×10−4T alternating current (AC) magnetic field, confirming the development of a multifunctional energy harvester.

Morphological and electrical investigations of lead zirconium titanate thin films processed at low temperature by a novel sol-gel system

Lead zirconate titanate (PZT) films prepared from a new chelate-based precursor solution were dip-coated onto ITO-coated glass substrates. ITO has been chosen to preserve the transparency necessary for the specific applications. The effects of chemistry and processing conditions are explored in solution-derived morphotropic composition PZT films. The PZT transformed directly from the amorphous phase into perovskite, without going through a pyrochlore intermediate stage. The PZT phase crystallized at significantly low temperature of 450 °C following conventional heat-treatment without necessitating special irradiations, rapid thermal annealing and/or particular substrates. Ferroelectric and dielectric properties were measured and compared for PZT films processed from two sol-gel precursor systems. A remanent polarization, Pr, of 7.5 μC cm−2, coercive field, Ec, of 18.7 kV cm−1, dielectric constant, εr, of 739, and loss value, tan(δ), of 0.04 were measured for PZT film post-annealed at 700 °C.

Effect of Gd doping on crystalline orientation, structural and electric properties of PZT thin films prepared by Sol-Gel methods

ABSTRACTGadolinium (Gd)-doped lead zirconium titanate (PGZT) thin films have been prepared by Sol-Gel methods to investigate the effects of Gd doping on crystalline orientation, structural and electric properties of lead zirconium titanate (PZT) films according to doping concentration from 0% to 5%. Conventional heat process and appropriate doping concentration, without introducing a single crystal seed layer, were used for obtaining (100)-oriented PGZT thin films with dense columnar structures. The maximum dielectric constant (1310.35 at 100 Hz) and the optimum ferroelectric properties were obtained for 2% Gd-doped film. 1% Gd-doped PZT film exhibited excellent piezoelectric properties.

Preparation and characterization of PZT thin films deposited on PZT buffer layer with different lead content

ABSTRACTLead zirconate titanate (PZT) thin films deposited on Pt electrode and Pb1+x(Zr0.52,Ti0.48)O3 (x = 0.10, 0.15, 0.25, 0.30) buffer layer have been prepared by sol-gel methods to investigate the effects of lead content in the buffer layer on crystalline orientation, electric and fatigue properties of PZT films. XRD and SEM showed that all films exhibited dense perovskite structure with (100) preferential orientation. The maximum dielectric constant (1571 at 100 Hz) was obtained in the PZT film with buffer layer containing 25% excess lead, which increased by 42.5% compared with the film without buffer layer. Fatigue resistance was improved by introducing buffer layer.

Substrate temperature-dependent physical properties of nanocrystalline zirconium titanate thin films

Nanocrystalline zirconium titanate thin films were deposited by direct current magnetron reactive sputtering on to glass substrates at room temperature and at different substrate temperatures of 423, 473, 523, and 573 K under high vacuum conditions. The deposited films have been characterized to study the physical properties of the films as a function of substrate temperature. Though the film exhibited amorphous characteristics at room temperature the higher temperatures resulted in the evolution of crystallites in the films. The crystallinity increased with temperature from 423 K onwards and the film deposited at 523 K exhibited a high crystallite size of 22 nm. The SEM images of the films revealed the improvement in the crystallinity from 423 to 523 K with dense columnar structure normal to the substrate. Further higher treatment deteriorated the film properties. The films showed a good transmittance of above 80%. A high optical transmittance of 91% and a high packing density of 96% have been observed for the film deposited at 523 K. The thickness of the films remained consistent at ~230 nm (±6 nm). It is noticed that an increase in the substrate temperature enhanced the structural, optical, and electrical properties of the films up to 523 K.

Performance of magnetoelectric PZT/Ni multiferroic system for energy harvesting application

Magnetoelectric (ME) coefficient of Lead Zirconium Titanate (PZT) thin films has been probed for possible energy harvesting applications. Single phase PZT thin films have been deposited on nickel substrate (PZT/Ni) using pulsed laser deposition (PLD) technique. The effect of PLD process parameters on the ME coupling coefficient in the prepared systems has been investigated. The as grown PZT films on Ni substrate were found to be polycrystalline with improved ferroelectric and ferromagnetic properties. The electrical switching behavior of the PZT thin films were verified using capacitance voltage measurements, where well defined butterfly loops were obtained. The ME coupling coefficient was estimated to be in the range of 94.5 V cm−1 Oe−1–130.5 V cm−1 Oe−1 for PZT/Ni system, which is large enough for harnessing electromagnetic energy for subsequent applications.

Optimization of post deposition annealing temperature of direct current magnetron reactive sputtered zirconium titanate thin films for refractory oxide applications

Nano crystalline Zirconium titanate thin films with Zr/Ti/O compositions of 51.22/45.32/3.46 have been deposited on to the glass substrates at a substrate temperature of 250 °C under ultra high vacuum conditions by employing direct current magnetron reactive sputtering. Later on the sputtered films were treated with post deposition rapid thermal annealing with temperatures ranging from 100 to 600 °C for 1 h in a flowing Oxygen (1 standard cubic centimeter) atmosphere. The micro structural, optical, electrical and morphological film properties have been analyzed as a function of annealing temperature by employing x ray diffraction in glancing incident angle mode, ultra violet visible spectroscopy, four point probe technique, atomic force microscopy, scanning electron microscopy and energy dispersive x ray analysis studies. The evolution of structural properties began at an annealing temperature of 300 °C and improved up to 500 °C. Annealing resulted in the re crystallization in the films. Once the re crystallization of amorphous films has occurred, the annealing temperature did not affect the film thickness. However higher temperatures promote inter diffusion of the substrate and film elements, which is undesirable. Here the films exhibited smooth, crack free, homogeneous micro structure and a consistent thickness of ∼400 nm. From the results obtained it is found that the optimal annealing temperature range is 400–500 °C.

Piezoelectric-film-based acoustic emission sensor array with thermoactuator for monitoring knee joint conditions

This paper presents a novel piezoelectric lead zirconium titanate (PZT) thin film acoustic emission (AE) sensor array equipped with thermoresponsive polymer actuators that enhance its sensitivity for monitoring knee joint conditions. A hydrothermal PZT film was grown on a micromachined titanium-film four-beam array for use as an acoustic sensing material. The thickness of the grown film was 10μm and its grain size was less than 1μm. Moreover, it had a perovskite structure and demonstrated strong piezoelectric properties. A thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPA) was formed on the beam array to electrically control the pressure on the sensing beam array and the underlying micropins. Such control was required for achieving an excellent couple for detecting a target, thereby increasing the sensitivity to AE signals. The fabricated PNIPA actuator was observed to generate more than 0.5% strain under a load six times its weight. Furthermore, the array configuration rendered the AE source detection more accurate compared with a regular single-detection-head sensor. The developed AE sensor was used for noninvasively examining the knee joint condition of a porcine leg when executing continuous back-and-forth motion. The result indicated that a joint under moderate extensive motion yielded higher AE signal amplitude and a wider bandwidth at major dominant frequencies compared with the joint before its extensive motion. An over-exercised joint with obvious cartilage degeneration yielded considerably high AE amplitude and a change in the pattern of dominant frequency peaks.