Irreversible Domain Research Articles

Exploring the mechanisms of enhanced piezoelectric properties in (K,Na)NbO3 single crystals

(K,Na)NbO3 (KNN)-based piezoelectric materials are candidates for replacing Pb-based materials. However, the piezoelectric properties of existing KNN-based single crystals are still inferior to those of Pb-based relaxor ferroelectric single crystals. Moreover, the piezoelectric response mechanism of KNN-based single crystals remains unclear. In this study, (Li,K,Na)(Nb,Sb,Ta)O3:Mn (KNNLST:Mn) single crystals with an excellent piezoelectric coefficient d33 of approximately 778 pC/N were prepared. Systematically studies of intrinsic and extrinsic piezoelectric responses have revealed that the high d33 of KNNLST:Mn single crystals is related to the shear piezoelectric response of a single-domain state and irreversible domain wall motion of the engineering domains. Furthermore, the effect of the orthorhombic (O)-tetragonal (T) phase boundary on intrinsic and extrinsic piezoelectric response is systematically studied, and the impact mechanism is elucidated. The results indicate that a lower dielectric response and elastic constant limit the intrinsic shear piezoelectric response of KNNLST:Mn single crystals, and approaching the O–T phase boundary can enhance both intrinsic and extrinsic piezoelectric responses. This study improves our understanding of the structure-performance relationship in KNN-based single crystals and offers insights for optimizing piezoelectric properties in KNN-based materials.

Mechanical properties and multi-field ferroelastic response of Nb/Mn Co-doped CaBi4Ti4O15 high-temperature ferroelectric ceramics

CaBi4Ti4O15 (CBT) ceramics are promising piezoelectric materials that have been widely studied for high-temperature applications. Despite significant advancements in the electrical performance of CBT ceramics, the understanding of their mechanical behaviors remains limited, which is unfavorable for designing ceramics with high stability and reliability during high-temperature service. This work investigated the mechanical properties and fracture behaviors of Nb/Mn co-doped CaBi4Ti4O15 (CBTNM) with various doping levels, focusing on stress-strain responses and ferroelastic deformation behaviors under uniaxial compression and multi-field coupling conditions. HRTEM analysis reveals small-scale layered domain wall structures on the surface of plate-like grains. The fracture and compressive strengths of CBTNM ceramics initially decrease and then increase with an increase in doping content, and the underlying mechanisms are related to grain size, defects, and densification. CBTNM ceramics exhibit nonlinear stress-strain responses due to ferroelastic deformation under compressive loading, and the resultant irreversible domain switching strain increases with an increase in doping content, while poling can further increase the residual strain. Under multi-field loading conditions, CBTNM ceramics undergo more ferroelastic deformation events and exhibit larger residual strain. The micro-cracks, pores, complicated fracture modes, and degraded fracture surfaces with fragmental and rough features are mainly responsible for the lower elastic modulus and inferior mechanical response. This work enhances our understanding of the mechanical behaviors of high-temperature piezoelectric ceramics and provides guidance for designing high-performance piezoelectric materials for complex environmental applications.

Role of polarization evolution in the hysteresis effect of Pb-based antiferroelecrtics

The electric field-induced irreversible domain wall motion results in a ferroelectric (FE) hysteresis. In antiferroelectrics (AFEs), the irreversible phase transition is the main reason for the hysteresis effects, which plays an important role in energy storage performance. Compared to the well-demonstrated FE hysteresis, the structural mechanism of the hysteresis in AFE is not well understood. In this work, the underlying correlation between structure and the hysteresis effect is unveiled in Pb(Zr,Sn,Ti)O3 AFE system by using in-situ electrical biasing synchrotron X-ray diffraction. It is found that the AFE with a canting dipole configuration, which shows a continuous polarization rotation under the electric field, tends to have a small hysteresis effect. It presents a negligible phase transition, a small axis ratio, and electric field-induced lattice changing, small domain switching. All these features together lead to a slim hysteresis loop and a high energy storage efficiency. These results offer a deep insight into the structure-hysteresis relationship of AFEs and are helpful for the design of energy storage material.

Structural mechanisms of large piezoelectric responses in BiFeO3-PbTiO3 based solid-solution ceramics

Achieving large piezoelectric response and high Curie temperature, simultaneously, are of great demand but have been rarely achieved in BiFeO3-PbTiO3 (BF-PT) based morphotropic phase boundary (MPB) systems. In this work, in-situ synchrotron x-ray diffraction and transmission electron microscopy were carried out in BF-PT-0.19Ba(Zr,Ti)O3 high-temperature piezoceramic, a recently reported MPB composition with high piezoelectric coefficient, to elucidate the underlying structural mechanism. A field induced irreversible transition from tetragonal (T) P4mm phase to rhombohedral (R) R3c phase is identified although R and T phases are still coexisted after poling. This induces the significantly enhanced irreversible domain switching of both R and T phases and the reversible domain switching of R phase but only a slightly enhanced reversible switching of T phase of as compared with other BF-PT-x Ba(Zr,Ti)O3 MPB compositions, leading to the significant increase of lattice strain up to ∼0.15% but only a slightly increase of strain from extrinsic domain switching due to the strong coupling between lattice strain and domain switching in both R and T phases, although the strain contribution seems to be composition independent after the field induced irreversible phase transition. The present study demonstrates a new performance enhancement mechanism to design the high-performance BF-PT based high-temperature piezoelectric ceramics in terms of the different roles of R and T phases within MPB.

Enhancing Electromechanical Properties of PZT-Based Piezoelectric Ceramics by High-Temperature Poling for High-Power Applications.

Defect engineering is a proven method to tune the properties of perovskite oxides. In demanding high-power piezoelectric ceramic applications, acceptor doping is the most effective method to harden ceramics, but it inevitably degrades the ceramics' electromechanical properties. Herein, a poling method based on acceptor doping, namely, high-temperature poling, is implemented by applying an electric field above the Curie temperature for poling to achieve a balance of the properties of piezoelectric coefficient d33 and mechanical quality factor Qm. After high-temperature poling, the piezoelectric property of 0.6 mol % Mn-doped Pb0.92Sr0.08(Zr0.533Ti0.443Nb0.024)O3 is d33 = 483 pC/N and Qm = 448. Compared with the traditional poling, the piezoelectric coefficient d33 of the high-temperature poling ceramics increased by approximately 40%, and Qm also increased by nearly 18%. Therefore, high d33 and Qm were exhibited by our PZT piezoelectric ceramics. Rayleigh's law analysis, XRD, and transmission electron microscopy analysis show that, after high-temperature poling, the considerably increased d33 is related to the large increase in the reversible domain wall motion in the intrinsic effect, while the slightly increased Qm is related to the inhibited irreversible domain wall motion in the extrinsic effect. This study reports a method for high-temperature poling and provides insights into the design of high-power piezoelectric ceramics with high d33 and Qm.

Logic and Memory Ferroelectric Field-Effect-Transistor Using Reversible and Irreversible Domain Wall Polarization

We propose a higher- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\kappa $ </tex-math></inline-formula> non-hysteric ferroelectric field-effect transistor (FEFET) using reversible domain wall displacement. By separately stimulating reversible and irreversible domain walls, whose concepts have been experimentally suggested recently, our HfZrOx-based FEFET showed remarkable performance as both a logic and a memory device. This was achieved by relatively low-temperature annealing, contributing to the formation of more reversible domain walls in the film. Finally, we demonstrated the feasibility of logic and memory co-integration by common fabrication process with complementary metal-oxide-semiconductor (CMOS) compatibility.

Effects of LiF on the properties of (Ba, Ca)(Ti, Sn, Hf)O3‐based multilayer ceramics co‐fired with Ni at reduced atmosphere

AbstractIn this work, (Ba0.97Ca0.03)(Ti0.96Sn0.005Hf0.035)O3–0.03MnCO3–xLiF (BCTSH–0.03M–xL, x = 0–6 mol%) multilayer piezoelectric ceramics were prepared by the solid‐state synthesis technique. The microstructure and piezoelectric properties of the samples sintered at the reduced atmosphere and co‐fired with the Ni base metal inner electrode were studied. The results showed that 3 mol% LiF could effectively reduce the sintering temperature from 1350 to 1200°C. BCTSH–0.03M–3L ceramics exhibited excellent electrical properties with d33 = 277 pC/N, d31 = −132 pC/N, kp = 0.350, Qm = 315, and εr = 3387. Furthermore, the complex impedance spectroscopy (e.g., activation energy) was used to analyze the doping mechanism of these obtained ceramics sintered at reduced atmosphere. The results indicated when LiF was added in a small amount (x ≤ 3), the bulk density was enhanced, and thus, the activation energy was also increased. Moreorver, when x &gt; 3, Li ions could partly enter the interstitial site of crystal structure resulting in the increase of activation energy. Rayleigh behaviors of reversible and irreversible domain wall contributions were analyzed. It was observed when x = 3, there was a larger Rayleigh coefficient, suggesting that this sample had the weaker pinning effect, and thus contributing to the higher d33 value due to the irreversible domain wall contribution. As x &gt; 3, the Rayleigh coefficient was found to decrease with increasing x due to the formation of the second phase, which could inhibit the motion of extrinsic domain wall. Finally, five‐layer multilayer piezoelectric ceramics co‐fired with inner Ni electrode were fabricated, and the electrical properties of five‐layer multilayer piezoelectric ceramics were found to be d33 = 1468 pC/N, d33* = 2000 (at 20 kV/cm), and kp = 0.342. To the best of our knowledge, the (Ba, Ca)(Ti, Sn, Hf)O3‐based lead‐free multilayer piezoelectric ceramics co‐fired with Ni‐based metal was first reported by us and used as the alternative multilayer ceramics for piezoelectric device applications.

Sb2O3‐modified lead zirconate titanate piezoelectric ceramics with enhancing piezoelectricity and low loss

AbstractLead zirconate titanate (PZT)–based piezoelectric ceramics as important functional materials are widely used in many electromechanical devices. The piezoelectric coefficient and mechanical quality factor are vital property parameters for piezoelectric applications. However, the piezoelectric coefficient is inversely proportional to the mechanical quality factor, resulting in a strong limitation among wide applications. Herein, piezoelectric ceramics composed of (xSb2O3, 0.3‐wt% MnCO3)‐doped (Pb0.92Sr0.08)(Zr0.533Ti0.443Nb0.024)O3 ((xSb, Mn)‐PSZTN) were prepared by a conventional solid‐state process. The excellent piezoelectric properties d33 = 554 pC/N, kp = 0.645, and high mechanical quality factor Qm = 540 were simultaneously obtained at x = 0.1 ceramic in the morphotropic phase boundary region. The enhancement of piezoelectric properties was mainly due to the contribution of irreversible domain wall motion. In particular, the regulation of different defect chemical reactions on the properties showed that Sb2O3 could play the role of both donor and acceptor dopant. This work demonstrated that (0.1Sb, Mn)‐PSZTN ceramic was a good candidate material for high‐power piezoelectric devices.

Temperature dependence of dielectric properties and domain structure of (K,Na)(Nb,Ta)O3 single crystal

In this work, the influence of temperature on phase structure, dielectric property and domain structure of (K,Na)(Nb,Ta)O3 (KNNT) crystal from 20 to 200 °C was studied. The irreversible domain wall motion of single crystal is strongest at phase transition temperature by Rayleigh analysis of dielectric properties. The domain structure in the heating and cooling process of single crystal was observed by means of piezoelectricity microscope. The domain structure changed obviously with temperature and the domain structure change is particularly prominent at the phase transition temperature.

Influence of Varying Tensile Stress on Domain Motion.

Magnetic domain motion has been widely studied in the fields of spintronics, nanowires, and thin films. However, there is a lack of such studies on industrial steels, especially for domain motion under the action of varying stress. Understanding domain motion under stress is helpful for the improvement of evaluation accuracy and the establishment of theoretical models of passive, nondestructive testing technology. This paper presents the influence of varying tensile stresses on the magnetic domain motion of silicon steel sheets. Magnetic domain rotation and domain wall displacement were characterized using magnetic domain images, and their motion mechanisms under elastic and plastic stresses are presented. The results show that the domain rotation under stress involves reversible and irreversible changes. The effect of material rearrangement on domain rotation and domain wall displacement after plastic deformation is discussed. Based on the motion mechanism, a threshold stress value (TSV) required for the complete disappearance of the supplementary domains in the elastic range is proposed, enabling the classification of the elastic stress ranges in which the reversible and irreversible domain rotations occur. In addition, the effect of microstructure on TSV is also discussed, and the results show that the regions far away from the grain boundary need larger stresses to complete an irreversible domain rotation. Additionally, the domain width and orientation also affect the TSV. These findings regarding the domain motion mechanism and TSV can help to explain the sequence of domain rotation under stress and modify the stress assessment under dynamic loads in electromagnetic nondestructive evaluation, especially in the magnetic memory method.

CBRW: a novel approach for cancelable biometric template generation based on 1-D random walk.

Cancelable Biometric is a challenging research field in which security of an original biometric image is ensured by transforming the original biometric into another irreversible domain. Several approaches have been suggested in literature for generating cancelable biometric templates. In this paper, two novel and simple cancelable biometric template generation methods based on Random Walk (CBRW) have been proposed. By employing random walk and other steps given in the proposed two algorithms viz. CBRW-BitXOR and CBRW-BitCMP, the original biometric is transformed into a cancelable template. The performance of the proposed methods is compared with other state-of-the-art methods. Experiments have been performed on eight publicly available gray and color datasets i.e. CP (ear) (gray and color), UTIRIS (iris) (gray and color), ORL (face) (gray), IIT Delhi (iris) (gray and color), and AR (face) (color). Performance of the generated templates is measured in terms of Correlation Coefficient (Cr), Root Mean Square Error (RMSE), Peak Signal to Noise Ratio (PSNR), Structural Similarity (SSIM), Mean Absolute Error (MAE), Number of Pixel Change Rate (NPCR), and Unified Average Changing Intensity (UACI). By experimental results, it has been proved that proposed methods are superior than other state-of-the-art methods in qualitative as well as quantitative analysis. Furthermore, CBRW performs better on both gray as well as color images.

Irreversible domain evolutions and formation mechanism of relaxor ferroelectric 0.91PZN-0.09PT single crystals

Irreversible domain evolutions and formation mechanism of relaxor ferroelectric 0.91PZN-0.09PT single crystals

Origin of the thickness-dependent electric properties of BiScO3-PbTiO3 piezoceramics near the morphotropic phase boundary

The mechanism of thickness dependence electric properties for BiScO3-PbTiO3 ceramics with morphotropic phase boundary has been investigated. With increasing the sample thickness from 0.2 mm to 1.0 mm, the dielectric constant and piezoelectric coefficient increase by 39% and 36%, respectively, and then become stable with further increase of the sample thickness up to 2.0 mm. Both XRD patterns and Raman spectra show the lattice distortion of tetragonal phase decreases with the thickness. Quantitative analysis of XRD patterns of ceramics with different thicknesses reveal that enhanced electric properties with sample thickness are owing to the improved contributions from lattice distortion, irreversible domain switching and irreversible phase transition from tetragonal to rhombohedral phase with the increases of thickness, which is quite different from the decreased domain size in PMN-PT single crystal. These results not only provide a new mechanism, but also give an important basis for piezoelectric transducer design based on BiScO3-PbTiO3 ceramics.

Unusual dynamic susceptibility arising from soft ferromagnetic domains in MnBi8Te13 and Sb-doped MnBiTe (n = 2, 3)

MnBiTe (MBT) is the first intrinsic magnetic topological insulator and is promising to host emergent phenomena such as quantum anomalous Hall effect. They can be made ferromagnetic by having or with Sb doping. We studied the magnetic dynamics in a few selected ferromagnetic (FM) MBT compounds, including MnBi8Te13 and Sb doped MnBiTe ( using AC susceptibility and magneto-optical imaging. Slow relaxation behavior is observed in all three compounds, suggesting its universality among FM MBT. We attribute the origin of the relaxation behavior to the irreversible domain movements since they only appear below the saturation fields when ferromagnetic domains form. The very soft ferromagnetic domain nature is revealed by the low-field fine-structured domains and high-field sea-urchin-shaped remanent-state domains imaged via our magneto-optical measurements. Finally, we ascribe the rare ‘double-peak’ behavior observed in the AC susceptibility under small DC bias fields to the very soft ferromagnetic domain formations.

Wake-up and fatigue mechanisms in ferroelectric Hf0.5Zr0.5O2 films with symmetric RuO2 electrodes

The mechanisms leading to wake-up and fatigue in ferroelectric hafnium zirconium oxide thin film devices with symmetric RuO2 electrodes are investigated via polarization, relative permittivity, dielectric nonlinearity, pyroelectric coefficient, and microfocus x-ray diffraction (XRD) measurements. The devices are observed to wake-up for up to 103 bipolar pulsed field cycles, after which fatigue occurs with polarization approaching zero following 108 cycles. Wake-up is accompanied by a decrease in both high-field permittivity and hysteresis loop pinching and an increase in the pyroelectric coefficient, indicating that the wake-up process involves a combination of transformations from the tetragonal to the orthorhombic phase and domain depinning from defect redistribution. Fatigue is observed to coincide with an increase in irreversible domain wall motion and a decrease in pyroelectric coefficient. Finite pyroelectric coefficients are measured on fully fatigued devices, indicating that domain pinning is a strong contributor to fatigue and that fatigued devices contain domain structures that are unable to switch under the fields applied for measurement. Microfocus XRD patterns measured on each device reveal that the phase constitution is qualitatively unaffected by field cycling and resultant polarization fatigue. These data indicate that the wake-up process has contributions from both phase transformations and domain depinning, whereas the fatigue process is driven primarily by domain pinning, and the near-zero measured switchable polarization is actually a poled device with immobile domains. These observations provide insight into the physical changes occurring during field cycling of HfO2-based ferroelectrics while examining a possible oxide electrode material for silicon CMOS device implementation.

Probing Metastable Domain Dynamics via Automated Experimentation in Piezoresponse Force Microscopy.

The dynamics of complex topological defects in ferroelectric materials is explored using automated experimentation in piezoresponse force microscopy. Specifically, a complex trigger system (i.e., "FerroBot") is employed to study metastable domain-wall dynamics in Pb0.6Sr0.4TiO3 thin films. Several regimes of superdomain wall dynamics have been identified, including smooth domain-wall motion and significant reconfiguration of the domain structures. We have further demonstrated that microscopic mechanisms of the domain-wall dynamics can be identified; i.e., domain-wall bending can be separated from irreversible domain reconfiguration regimes. In conjunction, phase-field modeling was used to corroborate the observed mechanisms. As such, the observed superdomain dynamics can provide a model system for classical ferroelectric dynamics, much like how colloidal crystals provide a model system for atomic and molecular systems.

Revealing intrinsic and extrinsic piezoelectric contributions in phase coexistence system of PbTiO3-BiScO3

PbTiO3-BiScO3 ceramics possess high piezoelectricity and high Curie temperature simultaneously, presenting a very promising candidate for high-temperature actuators and transducers. Figuring out the underlying piezoelectric mechanisms is of great importance for its application. Herein, we reveal the quantified intrinsic and extrinsic contributions to the high electrostrain of the morphotropic composition with phase coexistence by employing the advanced in situ electrical biasing high-energy synchrotron X-ray diffraction combined with the STRAP (strain, texture, and Rietveld analysis for piezoceramics from diffraction) methodology. An electric field-induced phase transformation is observed between the coexisting tetragonal and rhombohedral phases. It is found that the tetragonal phase contributes most of the domain switching strain, while the predominant lattice strain is from the rhombohedral phase. With phase fraction changes, the quantitative results demonstrate that the field-induced electrostrain is mainly contributed by the intrinsic lattice strain. In contrast, the high irreversible domain switching strain dominates the large remanent strain. It implies that transforming the large remanent strain into reversible strain would be a strategic direction to improve the piezoelectric response. The present results provide a further understanding of the high piezoelectricity and could help to advance the application of PbTiO3-BiScO3.

Influence of tensile vs. compressive stress on fatigue of lead zirconate titanate thin films

Novel applications of ferroelectric films require a variety of different substrates, which exert different mechanical stress on the film. This raises the question of reliability of differently stressed films. This work compares the cycling-induced fatigue of the polarization hysteresis of PZT films in different stress states. A tensile stress of +270 MPa, for PZT on fused silica glass, causes gradual degradation, while degradation sets in abruptly under compressive stress of −100 MPa, for PZT on sapphire. The main fatigue mechanism is domain wall pinning on charged defects. Reversible and irreversible domain wall processes in the small- and large-signal permittivity reveal that the fatigue behavior results from a variation of the ferroelectric domain structure. Films under tensile stress contain more 90° domain walls, which get pinned continuously on isolated defects. Compressive stress creates more 180° domain walls, which require formation of defect agglomerates during a certain threshold cycle number for pinning.

Understanding the correlation between intermediate monoclinic phase (Cc) and piezoelectric properties in NaNbO3-BaTiO3-CaZrO3 ternary system with octahedral tilt

Compared with traditional tetragonal (T) P4mm - rhombohedral (R) R3m morphotropic phase boundary (MPB) system, the structure-property relationship of MPB systems with octahedral tilt is still unclear. In this work, the phase structure evolution under composition and electric field modulations in lead-free (0.9-x)NaNbO3-0.1BaTiO3-xCaZrO3 (NN-BT-xCZ) close to the untilt P4mm-tilt R3c MPB was investigated in details by means of the ex- and in-situ x-ray diffraction and various electrical property measurements. Both P4 mm and R3c phases can irreversibly transform into a Cc phase under electric field loading, which should be considered as a result of the cooperative coupling between ferroelectric and antiferrodistortive instabilities. Quantitative analysis indicates that little composition dependent lattice strain and domain switching of P4 mm phase can be observed, and the variation of piezoelectric coefficient is closely related to Cc phase, which exhibits an enhancement of both lattice strain and domain switching within MPB. This suggests that lattice strain and domain switching of Cc phase are coupled. On the contrary, both of them are competed in P4 mm phase because the P4 mm phase is dominated by irreversible domain switching. The experimental results would benefit for deeply understanding the origin of piezoelectric response for many octahedral-tilt MPB piezoelectric systems.

Consideration of Magnetic Measurements for Characterisation of Ferrite–Martensite Commercial Dual-Phase (DP) Steel and Basis for Optimisation of the Operating Magnetic Field for Open Loop Deployable Sensors

The magnetic properties of commercial dual-phase (DP) steels (DP600, DP800 and DP1000 grades) were evaluated using initial permeability, incremental permeability and coercivity and correlated with the key microstructural differences between the grades. The ferrite grain sizes and ferrite fractions have been compared with the magnetic parameters obtained from minor and major magnetisation loops within each DP grade. It has been revealed that the incremental permeability increases with the applied magnetic field amplitude to reach a peak and then drops at a higher magnetic field, with the values being different for the three DP grades at a lower field and converging to a similar permeability value at the high field. The effects of ferrite grain size and phase fraction on the incremental permeability are considered, and it has been shown that the influence of ferrite grain boundaries on magnetic permeability is more dominant than the effect of ferrite fraction in commercial DP steel samples. An analysis of the correlation between coercivity and initial permeability with tensile strength shows that the initial permeability provides a slightly better prediction of strength for the steels examined, which is believed to be due to the fact that a combination of reversible and irreversible domain components affect the coercivity value, while the initial permeability is predominantly affected by reversible domain movements. Based on the trend between incremental permeability and applied magnetic field and the commercial EM sensor (EMspec) operating parameters, the effect of lift-off and hence magnetic field strength on the sensitivity to DP steel properties can be assessed.