Ferroelectric Lead Zirconate Titanate Research Articles

Enhancement of Ion-Sensitive Field-Effect Transistors through Sol-Gel Processed Lead Zirconate Titanate Ferroelectric Film Integration and Coplanar Gate Sensing Paradigm

To facilitate the utility of field effect transistor (FET)-type sensors, achieving sensitivity enhancement beyond the Nernst limit is crucial. Thus, this study proposed a novel approach for the development of ferroelectric FETs (FeFETs) using lead zirconate titanate (PZT) ferroelectric films integrated with indium–tungsten oxide (IWO) channels synthesized via a cost-effective sol-gel process. The electrical properties of PZT-IWO FeFET devices were significantly enhanced through the strategic implementation of PZT film treatment by employing intentional annealing procedures. Consequently, key performance metrics, including the transfer curve on/off ratio and subthreshold swings, were improved. Moreover, unprecedented electrical stability was realized by eliminating the hysteresis effect during double sweeps. By leveraging a single-gate configuration as an FeFET transformation element, extended-gate (EG) detection methodologies for pH sensing were explored, thereby introducing a pioneering dimension to sensor architecture. A measurement paradigm inspired by plane gate work was adopted, and the proposed device exhibited significant resistive coupling, consequently surpassing the sensitivity thresholds of conventional ion-sensitive field-effect transistors. This achievement represents a substantial paradigm shift in the landscape of ion-sensing methodologies, surpassing the established Nernst limit (59.14 mV/pH). Furthermore, this study advances FeFET technology and paves the way for the realization of highly sensitive and reliable ion sensing modalities.

Energy storage and dielectric properties in PbZrO3/PbZrTiO3 antiferroelectric/ferroelectric bilayer bulk structure using Landau theory

Employing Landau theory and the Landau–Khalatnikov (L–K) equation of motion, we investigate the phase transitions in individual layers of antiferroelectric lead zirconate (PbZrO3), ferroelectric lead zirconate titanate (PbZrTiO3), and an antiferroelectric/ferroelectric PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer bulk structure. We examine the dielectric hysteresis loop behavior of the three systems, with a specific focus on the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer under different stabilities of the PbZrO3 layer. In addition, we explore cases where the coercive field of the bilayer structure is lower than that of the PbZrTiO3 individual layer. The recoverable electric energy for the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer increases significantly to 118 J/cm3 at an applied field of 7.5 × 108 V/m at 20 °C. In comparison, the PbZr(0.21)Ti(0.79)O3 layer reaches 71.8 J/cm3 under the same field and temperature conditions. This is much higher than those predicted experimentally by previous studies on thin film single and bilayer structures (15.6 and 28.2 J/Cm3 respectively), indicating that the antiferroelectric/ferroelectric PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer bulk structure could be used to target specific large-scale, long-term energy storage applications. Upon increasing the value of the coupling coefficient, the transition temperatures of the PbZrO3 layer and the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer are increased up to the transition temperature of the PbZr(0.21)Ti(0.79)O3 individual layer (450 °C). This increment in the transition temperature in the bilayer system contributes to its stability in storing energy at higher temperatures. Furthermore, the recoverable energy density of the PbZrO3/PbZr(0.21)Ti(0.79)O3 bilayer increases further with temperature from 20 to 440 °C correlated with the rise in the difference between the spontaneous and the remanent polarizations (Ps − Pr). The significant stored energy observed over a wide temperature range highlights the promise of this bilayer structure for creating high-power capacitors where stability at different temperatures is crucial and possesses greater energy storage capacity.

Improvement of the structural, dielectric, ferroelectric, and piezoelectric of PbZr0.52Ti0.48O3 nanopowder features for ultrasonic applications

Smart ferroelectric lead zirconate titanate (PbZr0.52Ti0.48O3) was synthesized in the morphotropic phase boundary by a sol-gel auto-combustion strategy. The as-prepared powder was calcined at three different temperatures, 700, 800, and 900 °C for 3 h, each. The tetragonality of the final product increases with the rise of calcination temperature. Thermal gravimetric analysis and differential thermal gravimetric analysis depicted that complete crystallization of PZT was observed at 400 °C. Structural, vibrational, and microstructure studies were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy investigated for grains and elemental analyses and high-resolution transmission electron microscopy (HR-TEM). Results of XRD and HR-TEM were compatible, showing the formation of nanocrystalline powder with coexisting tetragonal and rhombohedral phases. Rietveld refinement of XRD data was carried out using material analysis using diffraction software in order to obtain the lattice constants. For mechanical and electrical measurements, disks were pressed at 10 MPa. The samples were burned out at 500 °C for 1 h and then 1100 °C for 2 h to obtain more dense disks. The surfaces of the disks were coated with silver paste, followed by burning out for almost an hour. Dielectric and piezoelectric characteristics for the fabricated PZT samples were determined in detail. From these analytical techniques and collected data, one can deduce that the sample annealed at 900 °C can be used as an ultrasonic transducer in various metrological applications.

Porous PZT Films: How Can We Tune Electrical Properties?

Porous ferroelectric lead zirconate titanate (PZT) films are a promising material for various electronic applications. This study focuses on understanding how the structure-directing agent, polyvinylpyrrolidone, can alter the structure and electrical properties of porous PZT films prepared through chemical solution deposition. Films with various porosities of up to ~40 vol.% and pore connectivities from 3-0 to 3-3 were prepared and studied by capacitance-voltage, dielectric hysteresis, transient current, photocurrent, and local current techniques. We have found that a linear decrease in material volume in a porous film is not the only factor that determines film properties. The creation of new internal grain boundaries plays a key role in changing electrical properties. This research expands the understanding of physical phenomena in porous ferroelectric films and may facilitate the development of new materials and devices.

Time-resolved piezoelectric response in relaxor ferroelectric (Pb0.88La0.12)(Zr0.52Ti0.48)O3 thin films

The domain switching dynamics in a relaxor ferroelectric lanthanum-modified lead zirconate titanate thin film with 12 mol. % La was investigated by time-resolved x-ray diffraction. While most frequently epitaxial thin films are investigated, the present work reports results on a polycrystalline thin film. Asymmetric butterfly loops of the strain as a function of the applied electric field evidenced a built-in electric field oriented toward the thin film–substrate interface. The piezoelectric coefficient d33 (in the film reference frame) diminishes with the increasing frequency of an applied AC electric field. From the strain transient during the application of positive-up negative-down voltage pulse sequences with frequencies of up to 100 kHz, characteristic times of the order of 100–200 ns were determined for these relaxor ferroelectric thin films. While switching times ranging from the picosecond to the millisecond range are reported in the literature for different materials, these characteristic switching times are comparable to epitaxial lead zirconate titanate thin films of various compositions despite the polycrystallinity of the present thin film. However, the evidenced built-in electric field significantly influences the switching behavior for different polarities.

Piezoelectricity in nominally centrosymmetric phases

Compound phases often display properties that are symmetry forbidden relative to their nominal, average crystallographic symmetry, even if extrinsic reasons (defects, strain, or imperfections) are not apparent. Specifically, breaking the macroscopic inversion symmetry of a centrosymmetric phase can dominate or significantly change its observed properties while the detailed mechanisms and magnitudes of the deviations of symmetry breaking are often obscure. Here, we choose piezoelectricity as a tool to investigate macroscopic inversion-symmetry breaking in nominally centrosymmetric materials as a prominent example and measure resonant piezoelectric spectroscopy (RPS) and Resonant Ultrasound Spectroscopy (RUS) in 15 compounds, 18 samples, and 21 different phases, including unpoled ferroelectrics, paraelectrics, relaxors, ferroelastics, incipient ferroelectrics, and isotropic materials with low defect concentrations, i.e., NaCl, fused silica, and ${\mathrm{CaF}}_{2}$. We exclude the flexoelectric effect as a source of the observed piezoelectricity yet observe piezoelectricity in all nominally cubic phases of these samples. By scaling the RPS intensities with those of RUS, we calibrate the effective piezoelectric coefficients using single-crystal quartz as standard. Using this scaling we determine the effective piezoelectric modulus in nominally nonpiezoelectric phases, finding that the ``symmetry-forbidden'' piezoelectric effect ranges from $\ensuremath{\sim}1$ to ${10}^{\ensuremath{-}5}$ pm/V ($\ensuremath{\sim}0.5%$ to $\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}%$ of the piezoelectric coefficient of poled ferroelectric lead zirconate titanate). The values for the unpoled ferroelectric phase are only slightly higher than those in the paraelectric phase. The extremely low coefficients are well below the detection limit of conventional piezoelectric measurements and demonstrate RPS as a convenient and ultrahighly sensitive method to measure piezoelectricity. We suggest that symmetry-breaking piezoelectricity in nominally centrosymmetric materials and disordered, unpoled ferroelectrics is a common phenomenon.

Tunable Microwave Conductance of Nanodomains in Ferroelectric PbZr0.2Ti0.8O3 Thin Film

AbstractFerroelectric materials exhibit spontaneous polarization that can be switched by electric field. Beyond traditional applications as nonvolatile capacitive elements, the interplay between polarization and electronic transport in ferroelectric thin films has enabled a path to neuromorphic device applications involving resistive switching. A fundamental challenge, however, is that finite electronic conductivity may introduce considerable power dissipation and perhaps destabilize ferroelectricity itself. Here, tunable microwave frequency electronic response of domain walls injected into ferroelectric lead zirconate titanate (PbZr0.2Ti0.8O3) on the level of a single nanodomain is revealed. Tunable microwave response is detected through first‐order reversal curve spectroscopy combined with scanning microwave impedance microscopy measurements taken near 3 GHz. Contributions of film interfaces to the measured AC conduction through subtractive milling, where the film exhibited improved conduction properties after removal of surface layers, are investigated. Using statistical analysis and finite element modeling, we inferred that the mechanism of tunable microwave conductance is the variable area of the domain wall in the switching volume. These observations open the possibilities for ferroelectric memristors or volatile resistive switches, localized to several tens of nanometers and operating according to well‐defined dynamics under an applied field.

Piezoelectric properties of PZT by an ethylene glycol-based chemical solution synthesis

We have investigated a water-stable sol–gel method based on ethylene glycol as a solvent and bridging ligand for the synthesis of ferroelectric lead zirconate titanate in bulk and thin film forms. This method offers lower toxicity of the solvent, higher stability toward atmospheric moisture and a simplified synthetic procedure compared to traditional sol–gel methods. However, the piezoelectric properties of products produced using this method have yet to be systematically studied. We have measured the ferroelectric and piezoelectric properties and compared them to existing literature using different synthesis techniques. Ceramic pellets of Nb-doped lead zirconate titanate (PNZT) in the tetragonal phase were produced with high density and good piezoelectric properties, comparable to those reported in the literature and those found in commercial piezoelectric elements. In addition, a nine-layer thin film stack was fabricated by spin coating onto platinized silicon substrates. The films were crack-free and showed a perovskite grain structure with a weak (111) orientation. Piezoelectric measurements of the film showed a piezoelectric coefficient comparable to literature values and good stability toward fatigue.

Strain-Mediated Magneto-Electric Effects in Coaxial Nanofibers of Y/W-Type Hexagonal Ferrites and Ferroelectrics

Nanofibers of Y- or W-type hexagonal ferrites and core–shell fibers of hexagonal ferrites and ferroelectric lead zirconate titanate (PZT) or barium titanate (BTO) were synthesized by electrospinning. The fibers were found to be free of impurity phases, and the core–shell structure was confirmed by electron and scanning probe microscopy. The values of magnetization of pure hexagonal ferrite fibers compared well with bulk ferrite values. The coaxial fibers showed good ferroelectric polarization, with a maximum value of 0.85 μC/cm2 and 2.44 μC/cm2 for fibers with BTO core–Co2W shell and PZT core–Ni2Y shell structures, respectively. The magnetization, however, was much smaller than that for bulk hexaferrites. Magneto-electric (ME) coupling strength was characterized by measuring the ME voltage coefficient (MEVC) for magnetic field-assembled films of coaxial fibers. Among the fibers with Y-type, films with Zn2Y showed a higher MEVC than films with Ni2Y, and fibers with Co2W had a higher MEVC than that of those with Zn2W. The highest MEVC of 20.3 mV/cm Oe was measured for Co2W–PZT fibers. A very large ME response was measured in all of the films, even in the absence of an external magnetic bias field. The fibers studied here have the potential for use in magnetic sensors and high-frequency device applications.

Microstructure analysis of porous lead zirconate–titanate films

AbstractPorous ferroelectric lead zirconate–titanate (PZT) films with different internal structures are synthesized using a sol–gel technique and spin‐on deposition on platinized silicon substrates. The films’ porosity is engineered using various structure‐directing agents: polyvinylpyrrolidone with a molecular weight of 360 000 (1–6.6 wt.%) and block copolymer surfactants Brij 30 and Brij 76 (30–60 wt.%). The films’ structures are characterized by transmission electron microscopy. The PVP‐based films contain large, elongated pores with diameters as large as 100 nm. By contrast, the films prepared from solutions with block copolymers exhibit a small pore size depending on the surfactant molecular weight (10–19 nm for Brij 30 and 20–27 nm for Brij 76), with a mostly uniform distribution of channel‐like pores within the film volume. Despite their highly porous structures, all of the films show a columnar‐grain perovskite structure with grains as large as several micrometers and curved grain boundaries. The films demonstrate ferroelectric behavior with dielectric hysteresis, and their permittivity decreases with increasing porosity. Thus, the Brij 30 and Brij 76 copolymer surfactants can be used to engineer fine porous structures in PZT films for various applications in electronics.

Reversible and Tunable Second‐Order Nonlinear Optical Susceptibility in PZT Thin Films for Integrated Optics (Advanced Optical Materials 16/2021)

A laser beam passing through a thin ferroelectric lead zirconate titanate (PZT) film is transformed into a beam with doubled frequency by means of second harmonic generation. The polarization density of the PZT film and the second-order susceptibility can be controlled and reserved by means of an applied voltage. The thin film exhibits a very strong susceptibility of 128 pm/V, which opens avenues for highly efficient and tunable on-chip nonlinear devices. For further details, see article number 2100149 by Gilles F. Feutmba, Jeroen Beeckman and co-workers.

Recent Developments on Ferroelectric PZT-Photovoltaics

The silicon based solar cells are expensive, and also said to have limited power conversion efficiency. Though a lot of organic, inorganic and organic-inorganic hybrid solar cells were developed, they could not sustain in long run. This has open doors for the development the ferroelectric based solar cells/photovoltaics. Because the ferroelectric based photovoltaics show high open circuit voltage, short circuit current/current density, unlimited power conversion efficiency, tunable bandgap, high polarization properties, etc. The main reason to shift the focus from semiconductor solar cells is,the ferroelectrics are said to be stable under changing environmental conditions. In addition, such materials help to develop thinner solar cells devices with low cost. Hence, an attempt has been made to understand the photovoltaic response of ferroelectric lead zirconate titanate (PZT). In this paper, we report the review on the photovoltaic properties of PZT films. The literature was collected from various internet sources.

Inhomogeneous Electric Field-Induced Structural Changes in Soft Lead Zirconate Titanate Ferroelectric Ceramics

Inhomogeneous Electric Field-Induced Structural Changes in Soft Lead Zirconate Titanate Ferroelectric Ceramics

Recent Progress in Hybridized Nanogenerators for Energy Scavenging.

SummaryAs the world's demand for alternative energy increases, the development of green energy harvesters becomes ever more important. As a result, the creation of triboelectric (TENG), piezoelectric (PENG), and pyroelectric nanogenerators, electromagnetic generators (EMG), solar cells, and electrochemical cells is attracting interest in an effort to convert mechanical, thermal, magnetic, solar, and chemical energy into electricity. In order to take advantage of the ambient energies from our surrounding environment, the design of hybridized generator units that can simultaneously scavenge energy in a variety of forms continues to develop. These systems are being considered to satisfy the energy needs of a range of electronic devices and adapt to a variety of working environments. This review demonstrates the latest progress in hybridized nanogenerators in accordance with their structure, operating principle, and applications. These studies demonstrate new approaches to developing hybrid techniques and novel assemblies for efficiently harvesting environmental energy from a number of sources.

Defect Engineering in Lead Zirconate Titanate Ferroelectric Ceramic for Enhanced Electromechanical Transducer Efficiency

AbstractLead zirconate titanate (PZT)‐based piezoelectric ceramics are important functional materials for various electromechanical applications, including sensors, actuators, and transducers. High piezoelectric coefficient and mechanical quality factor are essential for the resonant piezoelectric application. However, since these properties are often inversely proportional, simultaneously high performances are hard to achieve, consequently, a wide range of applications are strongly restricted. In the present study, exceptionally well‐balanced performances are achieved in PZT‐based ceramics via innovative defect engineering, which involves multi‐scale coordination among defect dipole, domain‐wall density, and grain boundary. These materials are superior to many state‐of‐the‐art commercial counterparts, which can potentially satisfy high‐end requirements for advanced electromechanical applications, such as energy harvesting, structural health monitoring, robotic sensors, and actuator.

Strong Converse Magnetoelectric Effect in a Composite of Weakly Ferromagnetic Iron Borate and Ferroelectric Lead Zirconate Titanate

This report is on a model and experiment on the nature of mechanical-strain-mediated converse magnetoelectric (CME) effect in a composite of single-crystal iron borate, a canted antiferromagnet with a weak ferromagnetic moment, and ferroelectric lead zirconate titanate (PZT). The piezoelectric strain generated in PZT by an electric field E manifested as a shift in the quasiferromagnetic resonance (FMR) field in iron borate due to strong magnetoelastic interactions. The CME interaction strength determined from data on field shift in FMR versus E is 46--54 MHz cm/kV at 5.5--6.5 GHz. The strength of the CME is comparable to values reported for composites of ferrimagnetic oxides and PZT. A model that considers the effect of piezoelectric deformation on magnetic order parameters and magnetic resonance in iron borate is proposed for the CMEs in the composite and estimated ME coupling coefficients are in good agreement with data. The E tunability of the high-frequency AFMR mode at about 300 GHz is estimated to be on the order of 1.7 MHz kV/cm and is very small relative to the quasi-FMR mode. Composites of iron borate and ferroelectrics are very attractive for use in dual electric field and magnetic field tunable signal processing devices due to strong CME interactions and the need for a rather small bias magnetic field compared with traditional ferrimagnetic oxide based devices.

The enhancement mechanism of dielectric properties of Pb(Zr,Ti)O3 via (Mg2+,Sb3+) incorporation for supercapacitors

Due to the extraordinary versatility of the perovskite structure in accommodating different dopant ions in its structure, in recent years a huge number of multifunctional perovskite materials have been developed. In this work we aim to obtain high temperature-stable and huge dielectric constant materials for supercapacitors by doping divalent Mg2+ and trivalent Sb3+ ions into the octahedral sites, and divalent Sr2+ ions into the dodecahedral sites of lead zirconate-titanate perovskite. The resulting (Pb0.95Sr0.05)(Zr0.425Ti0.45Mg0.042Sb0.083)O3-δ is examined by X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), dielectric spectroscopy (DS) and resonance dielectric spectroscopy (RDS) in order to correlate composition, local structure, ion valence and chemical environment of the doped material with the dielectric properties. HRTEM evidences that a composite structure, with co-existent ferroelectric domains and relaxor nanodomains, is formed by doping. XPS shows that Sb3+ and Mg2+ substitute for the Ti4+/Zr4+ ions, pointing to these strong defects as the main cause for the appearance of the relaxor phase. DS and RDS found that the ferroelectric lead zirconate-titanate transforms into a re-entrant relaxor-ferroelectric composite with a huge dielectric constant of about 104 which remains stable (within ±10%) in the high temperature range up to 250 °C, pointing to this mechanism of relaxor phase re-entrance below the normal ferroelectric phase transition, as being responsible for the enhancement.

Reinvestigation of the photostrictive effect in lanthanum‐modified lead zirconate titanate ferroelectrics

AbstractPhotostriction of lanthanum‐modified lead zirconate titanate (PLZT) was commonly attributed to the combination of anomalous photovoltaic effect and inverse piezoelectric response. Herein, distinct photostrictions are detected in both poled and unpoled PLZT ceramics under 405 and 520 nm laser illuminations. The maximum photostriction around 0.09% is obtained in unpoled PLZT under 405 nm illumination, which is nine times of previously reported value that deduced from poled PLZT. The photoelectric and photovoltaic characterizations of poled/unpoled PLZT further evidence that the detected photostriction shows no direct association with the photovoltage‐induced inverse piezoresponse. The light‐induced microstructure changes observed by in situ piezoelectric force microscopy are revealed by domain evolutions along the boundaries. The possible photostriction mechanism of PLZT is attributed to the strong photo‐induced electron‐lattice coupling, which is suggested by the light‐induced changes of the Zr/Ti‐O‐Zr/Ti bonds reflected by the power‐dependent Raman spectra. This study extends the photostriction of PLZT to visible light range and will also stimulate reappraisal of the underlying mechanism of photostrictive effect involving ferroelectrics.

Photonic integration based on a ferroelectric thin-film platform

Photonic-integrated circuits (PICs) using ferroelectric materials are expected to be used in many applications because of its unique optical properties such as large electro-optic coefficients. In this study, a novel PIC based on a ferroelectric thin-film platform was designed and fabricated, where high-speed optical modulator, spot-size converters (SSCs), and a variable optical attenuator (VOA) were successfully integrated. A ferroelectric lanthanum-modified lead zirconate titanate (PLZT) thin film was epitaxially-grown by using a modified sol-gel method, and it exhibits large electro-optic coefficients (>120 pm/V) and low propagation loss (1.1 dB/cm). The optical modulator, a Mach-Zehnder type, exhibited a half-wave voltage (Vπ) of 6.0 V (VπL = 4.5 Vcm) and optical modulation up to 56 Gb/s. Also, the VOA (with attenuation range of more than 26 dB) was successfully integrated with the modulator. As a result, it is concluded that the developed ferroelectric platform can pave the way for photonic integration.

Electrical studies of Barkhausen switching noise in ferroelectric lead zirconate titanate (PZT) and BaTiO3: critical exponents and temperature-dependence

Previous studies of Barkhausen noise in PZT have been limited to the energy spectrum (slew rate response voltages versus time), showing agreement with avalanche models; in barium titanate other exponents have been measured acoustically, but only at ambient temperatures. In the present study we report the Omori exponent (0.95 0.03) for aftershocks in PZT and extend the barium titanate studies to a wider range of temperature.