Amplitude Hysteresis Research Articles

Dynamics of a horizontal magnetic pendulum in a repulsive magnetic field and driven by two coil magnets

We studied theoretically and experimentally in this work the nonlinear dynamics of a horizontal magnetic pendulum in a repulsive magnetic field controlled by two coil magnets. The mathematical equations of the system are derived using the magnetic charges interaction model. The system presents a single equilibrium point which is stable if the currents through the coils are positive. Considering the situation where the current through the coils is sinusoidal with a DC component, analytical calculations using the harmonic balance method and numerical simulations are also carried out. The results obtained are shown in terms of amplitude responses, time–displacement diagrams, and phase portraits. The two-parameter bifurcation diagrams are plotted showing the different dynamical behaviors considering the current amplitudes, frequency, angle between the coil magnets, and the modulation indexes as the control parameters. Amplitude jumps, hysteresis, and multistability are also observed. In the experimental part, the modulated current sources that can provide the required current in the coil magnets have been designed and implemented. The complete experimental setup of the magnetic pendulum is also presented. Good agreements are found between our theoretical results and experimental ones.

Weakly nonlinear analysis of a two-species non-local advection–diffusion system

Nonlocal interactions are ubiquitous in nature and play a central role in many biological systems. In this paper, we perform a bifurcation analysis of a widely-applicable advection–diffusion model with nonlocal advection terms describing the species movements generated by inter-species interactions. We use linear analysis to assess the stability of the constant steady state, then weakly nonlinear analysis to recover the shape and stability of non-homogeneous solutions. Since the system arises from a conservation law, the resulting amplitude equations consist of a Ginzburg–Landau equation coupled with an equation for the zero mode. In particular, this means that supercritical branches from the Ginzburg–Landau equation need not be stable. Indeed, we find that, depending on the parameters, bifurcations can be subcritical (always unstable), stable supercritical, or unstable supercritical. We show numerically that, when small amplitude patterns are unstable, the system exhibits large amplitude patterns and hysteresis, even in supercritical regimes. Finally, we construct bifurcation diagrams by combining our analysis with a previous study of the minimizers of the associated energy functional. Through this approach we reveal parameter regions in which stable small amplitude patterns coexist with strongly modulated solutions.

Optimization of MPB for Sn Substituted Lead Bismuth Zirconate Titanate Thin Films by the Electromechanical Behavior Related to Energy Storage Capacity

In this article, we examined the electromechanical behavior of Sn-substituted Lead Bismuth Zirconate Titanate thin films (PBZST thin films). Using the pulsed laser deposition technique (PLD), the thin film growth parameters of bismuth-doped PZST close to MPB were adjusted by varying the ∼(Zr, Sn)/Ti ratios. Thin films (∼250 nm) with the stoichiometric formula Pb0.985Bi0.01(Zr0.7Sn0.3) x Ti1 – x O3, (x = 0.935, 0.940, 0.945, and 0.950) were grown on a Pt/TiO2/SiO2/Si substrate using PLD technique at optimized conditions. P-E loop confirms that MPB is near x = 0.945, and further PFM measurements also confirmed the same. Analyzing the PFM phase and amplitude hysteresis loops, local piezo-electric coefficient and remnant strain values were computed as d33 = 330 pm/V and 0.33 at the MPB composition (x = 0.945).

Nonlinear flutter of a narrow truss girder

The nonlinear flutter of a narrow railway truss girder are studied through free vibration and forced vibration wind tunnel tests. Four functions are used to fit the structural amplitude-varying damping ratio under no wind condition, and the fourth-order polynomial has higher goodness-of-fit. The narrow truss girder shows nonlinear flutter of a velocity-restricted type without amplitude hysteresis. At large angles of attack (AoA), the vertical participation and the AoA have little effect on the onset wind speed and amplitude. While at medium AoAs, even a low vertical participation level will increase the onset wind speed and decrease the amplitude. At small AoAs, there is no vibration observed. The flutter derivative A2* is positive only in the limited reduced wind speed and amplitude range. The nonlinearity of self-excited lifting moment is higher only in the limited reduced wind speed and amplitude range, while that of self-excited lift is weaker and becomes stronger with the increasing amplitude and reduced wind speed. The negative aerodynamic damping is mainly provided by the flutter derivative A2* at small or large AoAs. Generally, the nonlinear flutter response is mainly controlled by the first-order component of the self-excited force, and the influence of high-order components can be ignored.

The Seismic Design Process of RC Column Components in SDOF System considering the Earthquake Duration Effect

In order to study seismic design process of RC (reinforced concrete) column components considering the effect of earthquake duration, the degradation law of capacity under random amplitude hysteresis history was conducted by the research group, and the estimation method for the energy dissipation capacity of RC column components was suggested. Furthermore, the correlation between the stiffness decay index and energy dissipation capacity, hysteresis histories, and structural parameters was proposed, and the performance classification criteria based on the stiffness decay index was established. On this basis, the connection between the stiffness decay index and structural parameters and seismic parameters was established, and the seismic design process of RC column components in SDOF (single degree of freedom) system was proposed. The research indicated that the proposed seismic design process based on stiffness decay index can effectively consider the effect of earthquake duration. The stiffness decay index is more suitable for defining structural damage than deformation index and Park-Ang index. The stiffness decay index establishes quantitative relationships with seismic parameters and structural parameters, facilitating performance-based design in engineering practice. The increase in earthquake duration exacerbates the damage of RC column components, and this effect is more pronounced at the beginning of the earthquake and gradually decreases over time.

Periodic Ferroelectric Stripe Domains in α-In2Se3 Nanoflakes Grown via Reverse-Flow Chemical Vapor Deposition.

The two-dimensional (2D) layered semiconductor α-In2Se3 has aroused great interest in atomic-scale ferroelectric transistors, artificial synapses, and nonvolatile memory devices due to its distinguished 2D ferroelectric properties. We have synthesized α-In2Se3 nanosheets with rare in-plane ferroelectric stripe domains at room temperature on mica substrates using a reverse flow chemical vapor deposition (RFCVD) method and optimized growth parameters. This stripe domain contrast is found to be strongly correlated to the stacking of layers, and the interrelated out-of-plane (OOP) and in-plane (IP) polarization can be manipulated by mapping the artificial domain structure. The acquisition of amplitude and phase hysteresis loops confirms the OOP polarization ferroelectric property. The emergence of striped domains enriches the variety of the ferroelectric structure types and novel properties of 2D In2Se3. This work paves a new way for the controllable growth of van der Waals ferroelectrics and facilitates the development of novel ferroelectric memory device applications.

Regulating the phase transition temperature of VO2 films via the combination of doping and strain methods

Phase change materials have the potential for reversible modulation of the physical and chemical properties of other materials, making them suitable for a wide range of applications. Among these phase change materials, VO2 is particularly attractive for electronic applications due to its ultrafast reversible phase transition at near room temperature (68 °C). Regulating the phase transition temperature of VO2, however, remains a challenge. In this study, two factors, i.e., film thickness and buffer layer, that can effectively regulate the phase transition temperature of VO2 films were introduced, and the effect of doping on the phase transition temperature was also investigated. The interfacial strain between the VO2 film and substrate was modulated by adjusting the film thickness and doping concentration in the buffer layer. This was to explore the effect of strain on the phase transition temperature of the film. Changes in VO2 lattice parameters were reflected by the shifts of XRD diffraction peaks. Test and measurement results show that the phase transition temperature of VO2 gradually increased as the interfacial strain increased. For instance, the phase transition temperature (Th) of the GeVO/AlGeO-3 sample reached 91.2 °C. Moreover, some samples exhibited increased abrupt parameters, such as phase transition amplitude and thermal hysteresis width. These findings have important implications for the use of VO2 materials in applications, including switches, sensors, and amnesic resistors.

Effect of Acoustic Oscillations on Non-Equilibrium State of Magnetic Domain Structure in Cubic Ni2MnGa Single Crystal.

Magnetic hysteresis is a manifestation of non-equilibrium state of magnetic domain walls trapped in local energy minima. Using two types of experiments we show that, after application of a magnetic field to a ferromagnet, acoustic oscillations excited in the latter can "equilibrate" metastable magnetic domain structure by triggering the motion of domain walls into more stable configurations. Single crystals of archetypal Ni2MnGa magnetic shape memory alloy in the cubic phase were used in the experiments. The magnetomechanical absorption of ultrasound versus strain amplitude was studied after step-like changes of a polarizing magnetic field. One-time hysteresis was observed in strain amplitude dependences of magnetomechanical internal friction after step-like variations of a polarizing field. We distinguish two ingredients of the strain amplitude hysteresis that are found in the ranges of linear and non-linear internal friction and show qualitatively different behavior for increasing and decreasing applied polarizing fields. The uncovered effect is interpreted in terms of three canonical magnetomechanical internal friction terms (microeddy, macroeddy and hysteretic) and attributed to "triggering" by acoustic oscillations of the irreversible motion of domain walls trapped in the metastable states. To confirm the suggested interpretation we determine the coercive field of magnetization hysteresis through the measurements of the reversible Villari effect. We show that the width of the hysteresis loops decreases when acoustic oscillations in the non-linear range of domain wall motion are excited in the crystal. The observed "equilibration" of the magnetic domain structure by acoustic oscillations is attributed to the periodic stress anisotropy field induced by oscillatory mechanical stress.

Amplitude response, Melnikov's criteria, and chaos occurrence in a Duffing's system subjected to an external periodic excitation with a variable shape.

The present study considers the nonlinear dynamics of a Duffing oscillator under a symmetric potential subjected to a pulse-type excitation with a deformable shape. Our attention is focused on the effects of the external excitation shape parameter r and its period. The frequency response of the system is derived by using a semi-analytical approach. Interestingly, the frequency-response curve displays a large number of resonance peaks and anti-resonance peaks as well. Surprisingly, a resonance phenomenon termed here as shape-induced-resonance is noticed as it occurs solely due to the change in the shape parameter of the external periodic force. The system exhibits amplitude jumps and hysteresis depending on r. The critical driving magnitude for the chaos occurrence is investigated through Melnikov's method. Numerical analysis based on bifurcation diagrams and Lyapunov exponent is used to show how chaos occurs in the system. It is shown that the threshold amplitude of the excitation to observe chaotic dynamics decreases/increases for small/large values of r. In general, the theoretical estimates match with numerical simulations and electronic simulations as well.

Controlling the crystalline orientation and textual morphologies of the VO2 film and the effect on insulator–metal transition properties

Monoclinic VO2 films were prepared over quartz substrates through thermal oxidation of sputtered vanadium films under continuous O2 flow in a vacuum. It was found that an additional vacuum pre-heating before the thermal oxidation could have a great effect on film crystalline orientation and textual morphologies. The film exhibits a preferable growth along [011] direction and consists of uniform small inter-connected nanoparticles, while the untreated film shows (200) orientation and is composed of large irregular nanoparticles that connect via disorder boundaries. The (011) orientated film shows slightly higher full solar and IR light modulations. The electric resistance results also show that the metal–insulator transition (MIT) of the (011) orientated film presents a larger amplitude, higher sharpness, and narrower hysteresis as compared to the (200) orientated film. The difference in textual structures of the orientated films is the main physical reason that affects the MIT of m-VO2 films.

The Effectiveness of Isoplumbagin and Plumbagin in Regulating Amplitude, Gating Kinetics, and Voltage-Dependent Hysteresis of erg-mediated K+ Currents.

Isoplumbagin (isoPLB, 5-hydroxy-3-methyl-1,4-naphthoquinone), a naturally occurring quinone, has been observed to exercise anti-inflammatory, antimicrobial, and antineoplastic activities. Notably, whether and how isoPLB, plumbagin (PLB), or other related compounds impact transmembrane ionic currents is not entirely clear. In this study, during GH3-cell exposure to isoPLB, the peak and sustained components of an erg (ether-à-go-go related gene)-mediated K+ current (IK(erg)) evoked with long-lasting-step hyperpolarization were concentration-dependently decreased, with a concomitant increase in the decaying time constant of the deactivating current. The presence of isoPLB led to a differential reduction in the peak and sustained components of deactivating IK(erg) with effective IC50 values of 18.3 and 2.4 μM, respectively, while the KD value according to the minimum binding scheme was estimated to be 2.58 μM. Inhibition by isoPLB of IK(erg) was not reversed by diazoxide; however, further addition of isoPLB, during the continued exposure to 4,4′-dithiopyridine, did not suppress IK(erg) further. The recovery of IK(erg) by a two-step voltage pulse with a geometric progression was slowed in the presence of isoPLB, and the decaying rate of IK(erg) activated by the envelope-of-tail method was increased in its presence. The strength of the IK(erg) hysteresis in response to an inverted isosceles-triangular ramp pulse was diminished by adding isoPLB. A mild inhibition of the delayed-rectifier K+ current (IK(DR)) produced by the presence of isoPLB was seen in GH3 cells, while minimal changes in the magnitude of the voltage-gated Na+ current were demonstrated in its presence. Moreover, the IK(erg) identified in MA-10 Leydig tumor cells was blocked by adding isoPLB. Therefore, the effects of isoPLB or PLB on ionic currents (e.g., IK(erg) and IK(DR)) demonstrated herein would be upstream of our previously reported perturbations on mitochondrial morphogenesis or respiration. Taken together, the perturbations of ionic currents by isoPLB or PLB demonstrated herein are likely to contribute to the underlying mechanism through which they, or other structurally similar compounds, result in adjustments in the functional activities of different neoplastic cells (e.g., GH3 and MA-10 cells), presuming that similar in vivo observations occur.

The magnetic properties of multiferroic Ba5Fe3F19−δ

In order to break the contradictory requirements of the outer shell electronic structure for multiferroism in oxide perovskites, multiferroic fluorides were selected to be studied, in which the ferroelectricity and ferromagnetism may both come from the same magnetic ions. Pure phase Ba5Fe3F19−δ powders were prepared by solid state reaction. Energy dispersive X-ray spectroscopy results indicate the deficiency of Fe. The mixed valence states of Fe3+ and Fe2+ are confirmed by X-ray photoelectron spectroscopy. The observation of amplitude and phase hysteresis loops measured by piezoresponse force microscopy indicates the ferroelectricity in Ba5Fe3F19−δ. The temperature dependent magnetization curves show a continuous increase with decreasing temperature, without clear phase transition. However, the temperature dependent inverse magnetic susceptibility (χ) follows the Curie–Weiss law above 150 K with Curie–Weiss temperature of −55 K, suggesting predominantly antiferromagnetic interactions between the Fe ions. The χT decreases with the temperature decreasing from 300 K, indicating the onset of weak antiferromagnetic interaction from temperature above 300 K. No hysteresis loop was observed for the magnetic dependent magnetization curves down to 5 K, indicating the lacking of long-range ordering. A peak was observed in the temperature dependent dielectric constant and dielectric loss at around 257 K, which was strongly suppressed by the application of 5 T magnetic field. The observation of magnetocapacitance effect confirms the magnetoelectric coupling, which originates from the magnetic and structural coupling.

Magnetic properties of multiferroic Pb5Fe3F19

Fluoride ferroelectrics containing 3d transition metal ions are potential single-phase multiferroics. Pure phase Pb5Fe3F19 powders are prepared by the solid-state reaction, which is confirmed by the X-ray diffraction with isostructure to Pb5Cr3F19. X-ray photoelectron spectroscopy confirms that Fe ions are in the valence state of +3. Ferroelectricity is confirmed by the observation of amplitude and phase hysteresis loops by piezoresponse force microscopy at room temperature. Two anomalies are observed at TN1 of 78 K and TN2 of 21 K in the temperature dependent magnetization (M−T) curves, which is due to the onset of two antiferromagnetic transitions. The bifurcation between the zero-field cooled and field cooled M−T curves at temperatures below TN1 of 78 K is attributed to competition of the complicated antiferromagnetic exchange coupling between the neighboring Fe3+ ions, leading to the magnetic relaxation. Small hysteresis with negligible coercivity can be observed in the field dependent magnetization curves below TN1. The magnetization and coercivity are significantly enhanced with further decreasing temperature, indicating the weak ferromagnetism. The observed ferromagnetism might be due to the magnetoelectric coupling between the ferroelectric polarization and magnetization, leading to the spin canting of the antiferromagnetic coupling between neighboring Fe3+ ions. The magnetoelectric coupling is confirmed by the observation of magnetodielectric effect, which is due to the strong magnetic and structural coupling.

Effective Accentuation of Voltage-Gated Sodium Current Caused by Apocynin (4'-Hydroxy-3'-methoxyacetophenone), a Known NADPH-Oxidase Inhibitor.

Apocynin (aPO, 4′-Hydroxy-3′-methoxyacetophenone) is a cell-permeable, anti-inflammatory phenolic compound that acts as an inhibitor of NADPH-dependent oxidase (NOX). However, the mechanisms through which aPO can interact directly with plasmalemmal ionic channels to perturb the amplitude or gating of ionic currents in excitable cells remain incompletely understood. Herein, we aimed to investigate any modifications of aPO on ionic currents in pituitary GH3 cells or murine HL-1 cardiomyocytes. In whole-cell current recordings, GH3-cell exposure to aPO effectively stimulated the peak and late components of voltage-gated Na+ current (INa) with different potencies. The EC50 value of aPO required for its differential increase in peak or late INa in GH3 cells was estimated to be 13.2 or 2.8 μM, respectively, whereas the KD value required for its retardation in the slow component of current inactivation was 3.4 μM. The current–voltage relation of INa was shifted slightly to more negative potential during cell exposure to aPO (10 μM); however, the steady-state inactivation curve of the current was shifted in a rightward direction in its presence. Recovery of peak INa inactivation was increased in the presence of 10 μM aPO. In continued presence of aPO, further application of rufinamide or ranolazine attenuated aPO-stimulated INa. In methylglyoxal- or superoxide dismutase-treated cells, the stimulatory effect of aPO on peak INa remained effective. By using upright isosceles-triangular ramp pulse of varying duration, the amplitude of persistent INa measured at low or high threshold was enhanced by the aPO presence, along with increased hysteretic strength appearing at low or high threshold. The addition of aPO (10 μM) mildly inhibited the amplitude of erg-mediated K+ current. Likewise, in HL-1 murine cardiomyocytes, the aPO presence increased the peak amplitude of INa as well as decreased the inactivation or deactivation rate of the current, and further addition of ranolazine or esaxerenone attenuated aPO-accentuated INa. Altogether, this study provides a distinctive yet unidentified finding that, despite its effectiveness in suppressing NOX activity, aPO may directly and concertedly perturb the amplitude, gating and voltage-dependent hysteresis of INa in electrically excitable cells. The interaction of aPO with ionic currents may, at least in part, contribute to the underlying mechanisms through which it affects neuroendocrine, endocrine or cardiac function.

Amplitude-dependent hysteresis of wave velocity in rocks n wide frequency range: an experimental study

This research belongs to the field of rock physics. In recent years, in solid state physics and materials science, new knowledge has emerged about microplastic strain of various materials, including rocks. These data were obtained using high-precision micro- and nanoscale strain measurements. The very fact of the existence of the poorly studied rock property in the earth sciences requires the study of the possible influence of the rock microplasticity on the propagation of seismic and acoustic waves. The studies were carried out using three alternative methods and under different observation conditions. The field measurements were carried out in the zone of low velocities in crosshole space with transmitted waves of frequency of 240–850 Hz. The laboratory measurements were carried out on sandstone samples with transmitted (6.8 kHz) and reflected (1 MHz) waves at the strain of 10−8–10−6. The manifestations of microplasticity were recorded using high-resolution recording of signals with discretization time tdiscret = 1 μs – 40 μs and 32.5 ns. The wave amplitude variation was provided in a closed cycle: discrete increasing the amplitude from minimum to maximum and return to the initial value (A1+ → A2+ → … Amax … → А2– → A1–). In this amplitude range, an amplitude hysteresis was observed, a sign of which was the inequality of wave velocities on the upward and downward amplitude courses. This effect was recorded for all three measurement methods at different frequencies. However, the amplitude hysteresis of the wave velocity was not observed only in the measurements at full water saturation of loam. The largest amplitude-dependent change in the wave velocity reached 2% (at the accuracy of 0.02%), and the change in the attenuation value amounted to 5%. The reason for this effect could be microplastic inelasticity, which manifested itself by amplitude plateaus located within the waveform. The amplitude microhysteresis forms overall picture of the amplitude dependence of the wave velocity in wide amplitude range. Proposals for the potential use of the obtained data for solving some applied problems have been presented.

Multilayered non‐uniform atomic force microscope piezoelectric microcantilever control and vibration analysis considering different excitation based on the modified couple stress theory

Atomic force microscope (AFM) is one of the most powerful tools for surface scanning, force measurement, and nano-manipulation. To improve its performance, vibration and control of AFM micro-cantilever (MC) should be studied. Hysteresis, as an undesired phenomenon affecting vibration amplitude and phase, is also another important issue to be examined. In this paper, vibration analysis and control of a ZnO non-uniform multi-layered piezoelectric MC has been investigated in non-contact mode. A modified couple stress theory has been used to obtain the strain energy for modeling the MC. In order to control the amplitude, a sliding mode controller (SMC) has been utilized on AFM, due to its application in uncertain and nonlinear systems. For applying the control signal, two methods of piezo and base actuation are studied. The results are compared with proportional integral derivative (PID) control method and it is demonstrated that SMC method reduces the control input close to the surface and increases the accuracy near the surface. In addition to MC control, hysteresis amplitude and phase differences are investigated by applying the Prandtl-Ishlinskii model. Also, surface topography is studied with hysteresis. The simulations show backward phase difference and an increase in amplitude, accordingly.

Moisture sorption characteristics of heat desiccated milk sweet ‘Khoa- peda’ prepared from Buffalo milk

Water activity (aw) is a valuable criterion in food processing affecting food product design and in ensuring food safety during storage. Khoa-peda is an indigenous khoa based dairy sweet prepared by mixing khoa and sugar and is popular all over India. It has a maximum shelf life of 15 days at refrigerated temperatures. The moisture sorption parameters of Khoa-peda prepared from buffalo milk were determined at three different temperatures 15, 25 and 35°C using a gravimetric-static method. The moisture sorption isotherms were found to be of sigmoid shape reflecting a Type II isotherm. At all water activities, the equilibrium moisture content was lower at higher temperatures. From amongst the GAB, Modified Mizrahi, Oswin, Caurie and Halsey models applied to the experimental sorption data of khoa-peda, the GAB model best described the sorption isotherm throughout the entire range of aw. Temperature dependence of GAB parameters was determined by using Arrhenius type equation to correlate the GAB constants with temperature. The hysteresis effect was observed at all the temperatures over the entire range of water activities. The hysteresis loop was of Type ‘C’ according to Everett classification. The effect of temperature was found to reduce the hysteresis. The hysteresis amplitude reduced from 0.303 at 15°C to 0.253 at 35°C, total hysteresis units decreased from 1.55 units at 15°C to 1.25 units at 35°C and the hysteresis energy reduced from 67.72 kJ/kg of water at 15°C to 32.25 kJ/kg of water at 35°C.

Investigation into Energy Dissipation During Grouting Uplift

Concrete covering damage is often caused by inadequate control of the grouting process. As such, in this work, a grouting nonlinear dynamic damage model was established to explore the concrete covering damage mechanism, which is crucial to the safety of dam grouting. Specifically, this study was designed to: (1) investigate the hysteresis energy dissipation and hysteresis damage mechanisms during the concrete covering’s dynamic response process and (2) assess the concrete covering’s nonlinear dynamic response and hysteresis energy dissipation under different grouting pressures, joint apertures, cement liquid viscosities, and grouting flows. The results show that the pulsation amplitude and cumulative hysteresis energy dissipation signifcantly affects the concrete covering damage rate, which quickly increases with damage energy dissipation rate in unstable grouting pressure.

Room temperature multiferroism in BaCoF4 films prepared by pulsed laser deposition

The much lower magnetic ordering temperature of multiferroic fluorides strongly limits their practical applications [J. F. Scott and R. Blinc, J. Phys. 23, 113202 (2011)]. In this paper, (010) oriented BaCoF4 films have been prepared on (0001) Al2O3 substrates by pulsed laser deposition. The clear observation of amplitude and phase hysteresis loops by piezoresponse force microscopy confirms the ferroelectricity at room temperature. In contrast to the antiferromagnetism in bulk BaCoF4 with a much lower Néel temperature of 69.6 K [Eibschütz et al., Phys. Rev. B 6, 2677 (1972)], clear magnetic hysteresis loops are observed in BaCoF4 films, indicating the weak room temperature ferromagnetism. The nearly unchanged saturated ferromagnetic magnetization of about 30 emu/cm3 between 5 K and 300 K suggests that the Curie temperature of BaCoF4 films is much higher than room temperature. Exchange bias is clearly observed, with a blocking temperature of 250 K. Magnetoelectric coupling is demonstrated by the observed magnetocapacitance effect at room temperature.

Determination of polarization states in (K,Na)NbO3 lead-free piezoelectric crystal

Polarization switching in lead-free (K0.40Na0.60)NbO3 (KNN) single crystals was studied by switching spectroscopy piezoresponse force microscopy (SS-PFM). Acquisition of multiple hysteresis loops on a closely spaced square grid enables polarization switching parameters to be mapped in real space. Piezoresponse amplitude and phase hysteresis loops show collective symmetric/asymmetric characteristics, affording information regarding the switching behavior of different domains. As such, the out-of-plane polarization states of the domains, including amplitudes and phases can be determined. Our results could contribute to a further understanding of the relationships between polarization switching and polarization vectors at the nanoscale, and provide a feasible method to correlate the polarization hysteresis loops in a domain under an electric field with the polarization vector states.