Piezoelectric Hysteresis Loops Research Articles

Ferroelectric BiFeO3 nanodots formed in non-crystallized BiFeO3 thin-films via a local heating process using a heated atomic force microscope tip

A BiFeO3 thin-film was prepared from a solution by deposition on a Pt/TiO2/SiO2/Si substrate via a spin coating process and was subsequently annealed at 300 °C for 1 h to afford a non-crystallized BiFeO3 thin-film. Locally crystallized BiFeO3 nanodots were formed in the non-crystallized BiFeO3 thin-film via a local crystallization process using an atomic force microscope tip heated to 550 °C. By controlling the local heating time, ferroelectric BiFeO3 nanodots with different diameters ranging from 65 to 120 nm were obtained. The ferroelectric properties of the BiFeO3 nanodots were further investigated by studying the local ferroelectric switching behaviors and local piezoelectric d33 hysteresis loops using a piezoresponse force microscope.

Local ferroelectric polarization switching properties of BiFeO3 nanodots and thin films depending on the ferroelectric polarization nanobit diameter

We investigated the local ferroelectric polarization switching characteristics of an epitaxial (001) BiFeO3 (BFO) thin film and BFO nanodots having 100–300-nm diameters. The 30-nm-thick BFO thin films were deposited on (100) Nb-doped SrTiO3 (Nb:STO) substrates via pulsed laser deposition. This large switching voltage of the BFO thin film originates from the neighboring domains that stabilize the ferroelectric polarization nanobit against the switching electric field induced by the external bias. The coercive voltages of the piezoelectric d33 hysteresis loops, which depend on the diameters of the BFO nanodots, were saturated to that of the BFO thin film, indicating that the influence of the neighboring domains is limited to within a diameter of approximately 300 nm.

Backswitching effect in relaxor SBN crystals, studied by PFM-spectroscopy

ABSTRACTWe present studies of local piezoelectric hysteresis loops Hω-UDC (PFM spectroscopy method) measured in SBN crystals under square pulse trains. The dependences of the loop height, i. e., of the remnant polarization Pr, on the pulse duration tp and spacing Δt were found at tp < 1000 ms. The effects are pronounced at tp/Δt < 1, which permits us to attribute them to backswitching. For the first time, the dependence of coercive fields on Δt was revealed, which as well as the backswitching is caused by Pr instability.

Multiferroic BiFeO3 thin films and nanodots grown on highly oriented pyrolytic graphite substrates

Multiferroic BiFeO3 (BFO) thin films and nanodots are deposited on highly oriented pyrolytic graphite (HOPG) substrates via a pulsed laser deposition technique, where the HOPG surface has a honeycomb lattice structure made of carbon atoms, similar to graphene. A graphene/BFO/HOPG capacitor exhibited multiferroic properties, namely ferroelectricity (a residual polarization of 26.8 μC/cm2) and ferromagnetism (a residual magnetization of 1.1 × 10−5 emu). The BFO thin film had high domain wall energies and demonstrated switching time of approximately 82 ns. An 8-nm BFO nanodot showed a typical piezoelectric hysteresis loop with an effective residual piezoelectric constant of approximately 110 pm/V and exhibited two clearly separated current curves depending on the ferroelectric polarization direction.

Experimental sea wave energy extractor based on piezoelectric Ericsson cycles

Recycling ambient energies with electric generators instead of employing batteries with limited lifespans has motivated a large scientist community over two decades. Sea waves exhibit a large energy density. The amount of energy that could be extracted from the sea waves is very high. This work describes a technique of sea wave energy extraction based on a piezoelectric conversion and an analogy with thermodynamic Ericsson loops. By synchronizing external electric field to the maximum and the minimum of the sea wave mechanical stress excitations, the piezoelectric material dielectric hysteresis loop area is increased corresponding to the maximum of the energy available. In this article, technical solutions are proposed for the in site deployment of the proposed technique (maximum and minimum detection, external electric field source synchronization). Experimental measuring benches have been developed to monitor the sea wave mechanical excitation and to determine precisely the energy-harvesting potential. Adequate dielectric hysteresis model is proposed to numerically determine the best configuration (frequency, amplitude) of electric field to impose. Even if the Ericsson technique requires external electronic devices, the weak consumption of such components allows a large enhancement of the amount of energy extracted compared to a basic piezo element conversion.

Domain-wall conduction in AFM-written domain patterns in ion-sliced LiNbO3 films

We report on the static conduction at domain walls (DWs) in stable domain gratings written by dc-AFM-tip voltages in thin (300–500–nm–thick) ion-sliced LiNbO3 films embedded to SiO2/LiNbO3 substrates. Steady currents were found at DWs by conductive atomic force microscopy. The currents at DWs are larger than those in switched and unswitched domains not less than by five orders of magnitude. The current–voltage characteristics at DWs differ fundamentally from the I-U curves in switched domains. Piezoelectric hysteresis loops Hf(Utip) measured over written gratings indicate that a contribution from the domain motion to the currents at DWs can be neglected. The scope of data obtained permits us to relate these currents unambiguously to the domain-wall conduction (DWC). DWC persists during observation times of about several months, i.e., its steadiness is determined by the stability of written domains.

Research Update: Enhancement of figure of merit for energy-harvesters based on free-standing epitaxial Pb(Zr0.52Ti0.48)0.99Nb0.01O3 thin-film cantilevers

All-oxide free-standing cantilevers were fabricated with epitaxial (001)-oriented Pb(Zr0.52Ti0.48)O3 (PZT) and Pb(Zr0.52Ti0.48)0.99Nb0.01O3 (PNZT) as piezoelectric layers and SrRuO3 electrodes. The ferroelectric and piezoelectric hysteresis loops were measured. From the zero-bias values, the figure-of-merits (FOMs) for piezoelectric energy harvesting systems were calculated. For the PNZT cantilever, an extremely large value FOM = 55 GPa was obtained. This very high value is due to the large shifts of the hysteresis loops such that the zero-bias piezoelectric coefficient e31f is maximum and the zero-bias dielectric constant is strongly reduced compared to the value in the undoped PZT device. The results show that by engineering the self-bias field the energy-harvesting properties of piezoelectric systems can be increased significantly.

Nanoscale investigation of ferroelectric and piezoelectric properties in (Pb,Ca)TiO3 thin films grown on LaNiO3/LaAlO3(1 0 0) and Pt/Si(1 1 1) using piezoresponse force microscopy

Single phase polycrystalline and strong textured Pb0.76Ca0.24TiO3 (PCT24) thin films have been grown on platinum coated silicon and LaAlO3(100) (LAO) substrates using LaNiO3 (LNO) as a buffer layer by chemical solution deposition. X-ray diffraction measurements showed that the PCT24 thin films crystallize in a highly a-oriented single phase on LNO/LAO(100). The effects of the LNO buffer layer, nature of the substrate, and film orientation on the ferroelectric and piezoelectric properties were investigated in the nanoscale range using piezoresponse force microscopy (PFM). Local piezoelectric hysteresis loops for PCT24/LNO/LAO(100) oriented films and PCT24/Pt/Si polycrystalline films were measured on selected grains. From these piezoloops, PCT24/LNO/LAO(100) oriented films show a higher response (maximum relative d33 value) than PCT24/Pt/Si polycrystalline films. Furthermore, the comparison of simultaneously acquired surface morphology and piezoresponse images of the PCT24/Pt/Si films revealed the presence of inactive grain regions. In contrast, highly a-oriented films showed a higher presence of active grains. Our observations suggest that the improvement of ferro/piezoelectric properties is greatly associated with the use of LNO buffer layers and the growth of highly a-oriented films.

Leakage current limiting mechanisms and ferroelectric properties of BiAlO3/La0.67Sr0.33MnO3 heterostructure

The BiAlO3/La0.67Sr0.33MnO3 heterostructure was deposited on LaAlO3 (111) substrate by pulse laser deposition technology. X-ray diffraction measurement indicates that BiAlO3 thin films belong to tetragonal phase. Two different leakage current mechanisms, i.e., Space Charge Limited Current and Schottky emission models are observed in J–E characteristics of BiAlO3/La0.67Sr0.33MnO3 heterostructure in different temperature regions, respectively. The ferroelectric hysteresis loops measured by positive-up negative-down method show intrinsic remnant polarization (2Pr = 2.4 μC/cm2) at the applied electric field of 750 kV/cm, with the 80 nm thickness of BiAlO3 thin films at room temperature. The domain imagines and local piezoelectric hysteresis loops obtained by Piezoresponse Force Microscopy technique further reveal the intrinsic ferroelectricity of. BiAlO3 thin films at room temperature.

Annealing temperature dependence of local piezoelectric response of (Pb,Ca)TiO3 ferroelectric thin films

In this work, we have systematically investigated the piezo/ferroelectric response of (Pb, Ca)TiO3 thin films prepared by polymeric precursor method using simultaneously topography, piezoresponse force microscopy (PFM) and local piezoelectric hysteresis loop measurements. The thin films were grown on Pt/Ti/SiO2/Si substrates and annealed at 400, 500 and 600°C and subjected to structural characterization using x-ray diffraction, infrared and micro-Raman spectroscopy. The ferroelectric domains structure and the piezoelectric response evolved as a function of thermal annealing temperature as well as the density of active grains (number of switchable domains) progressively increased. Another important characteristic of these films is the onset of large area showing the coexistence of active (stronger piezoresponse signal) and inactive (weak or non piezoresponse signal) grains embedded in the polycrystalline perovskite matrix. A combination of out-of-plane (OP) and in-plane (IP) PFM images revealed local features of polarization component magnitudes in samples surface. Well-defined local piezoelectric hysteresis loop was achieved on top of individual nanometer-scale grains in both samples annealed at 500 and 600°C, and the switching behavior is evident.

Highly Oriented Growth of Piezoelectric Thin Films on Silicon Using Two-Dimensional Nanosheets as Growth Template Layer.

Ca2Nb3O10 (CNOns) and Ti0.87O2 (TiOns) metal oxide nanosheets (ns) are used as a buffer layer for epitaxial growth of piezoelectric capacitor stacks on Si and Pt/Ti/SiO2/Si (Pt/Si) substrates. Highly (001)- and (110)-oriented Pb(Zr0.52Ti0.48)O3 (PZT) films are achieved by utilizing CNOns and TiOns, respectively. The piezoelectric capacitors are characterized by polarization and piezoelectric hysteresis loops and by fatigue measurements. The devices fabricated with SrRuO3 top and bottom electrodes directly on nanosheets/Si have ferroelectric and piezoelectric properties well comparable with devices that use more conventional oxide buffer layers (stacks) such as YSZ, CeO2/YSZ, or SrTiO3 on Si. The devices grown on nanosheets/Pt/Si with Pt top electrodes show significantly improved polarization fatigue properties over those of similar devices grown directly on Pt/Si. The differences in properties are ascribed to differences in the crystalline structures and the density of the films. These results show a route toward the fabrication of single crystal piezoelectric thin films and devices with high quality, long-lifetime piezoelectric capacitor structures on nonperovskite and even noncrystalline substrates such as glass or polished metal surfaces.

The effect of silicon-substrate orientation on the local piezoelectric characteristics of LiNbO3 films

The domain structure of lithium-niobate thin films grown on Si(111) and Si(100) substrates coated with a native oxide layer with a thickness of no less than 2 nm is investigated by X-ray diffraction, scanning electron microscopy and piezoresponse force microscopy. The films are synthesized by the rf magnetron sputtering of a single-crystal lithium-niobate target. A high degree of grain orientation in the polycrystalline films is demonstrated. The piezoelectric coefficients dzz of the lithium-niobate films on Si(111) and Si(100) substrates are calculated from the measured dependences of the amplitude of the piezoresponse signal on the ac voltage applied between the cantilever tip and the substrate. Piezoelectric hysteresis loops are obtained in the remanent piezoelectric response regime

Ferroelectric and electrical properties of lead-free (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 thin films

The Li, Ta, and Sb-substituted lead-free (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNLNTS) thin films were fabricated on Pt(111)/TiO2/SiO2/Si substrates using the radio frequency (RF) magnetron sputtering method. The KNLNTS thin films were annealed at 750 ◦C for 1 h in an oxygen ambient. The film with a thickness of 350 nm exhibited a typical ferroelectric P − E hysteresis loop without fatigue even after 1010 pulses. The KNLNTS thin film exhibited a relatively low leakage current density of ~10 −7 A/cm2 even up to an applied electric field of 142 kV/cm. A well-saturated piezoelectric hysteresis loop was obtained with a piezoelectric coefficient d33 of 21 pm/V.

Domain formation and polarization reversal under atomic force microscopy-tip voltages in ion-sliced LiNbO3 films on SiO2/LiNbO3 substrates

We report on studies on writing of micro- and nanodomains and specified domain patterns by AFM-tip voltages UDC in thin (0.5 μm thick) ion-sliced LiNbO3 films embedded to SiO2/LiNbO3 substrates. A peculiar feature is an overlapping of domains as the distance between them decreases. Piezoelectric hysteresis loops were measured in a wide range of UDC pulse durations. Domain dynamics and characteristics of hysteresis loops reveal marked distinctions from those observed so far in LiNbO3 films and bulk crystals.

Nanoscale Ferroelectric Switchable Polarization and Leakage Current Behavior in (Ba0.50Sr0.50)(Ti0.80Sn0.20)O3Thin Films Prepared Using Chemical Solution Deposition

Nanoscale switchable ferroelectric (Ba0.50Sr0.50)(Ti0.80Sn0.20)O3-BSTS polycrystalline thin films with a perovskite structure were prepared on Pt/TiOx/SiO2/Si substrate by chemical solution deposition. X-ray diffraction (XRD) spectra indicate that a cubic perovskite crystalline structure and Raman spectra revealed that a tetragonal perovskite crystalline structure is present in the thin films. Sr2+and Sn4+cosubstituted film exhibited the lowest leakage current density. Piezoresponse Force Microscopy (PFM) technique has been employed to acquire out-of-plane (OPP) piezoresponse images and local piezoelectric hysteresis loop in polycrystalline BSTS films. PFM phase and amplitude images reveal nanoscale ferroelectric switching behavior at room temperature. Square patterns with dark and bright contrasts were written by local poling and reversible nature of the piezoresponse behavior was established. Local piezoelectric butterfly amplitude and phase hysteresis loops display ferroelectric nature at nanoscale level. The significance of this paper is to present ferroelectric/piezoelectric nature in present BSTS films at nanoscale level and corroborating ferroelectric behavior by utilizing Raman spectroscopy. Thus, further optimizing physical and electrical properties, BSTS films might be useful for practical applications which include nonvolatile ferroelectric memories, data-storage media, piezoelectric actuators, and electric energy storage capacitors.

Structure and ferroelectric studies of (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 piezoelectric ceramics

We have synthesized and studied the structural and ferroelectric properties of lead-free 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.2Ti0.8)O3 ceramics in the temperature region of its ferroelectric transition. The synthesized material showed high dielectric constant, low loss and good pyroelectric figure of merit. From the temperature dependent X-ray diffraction measurements, we determined the tricritical point to be in the temperature range of 303–400K. The dielectric measurements indicate a diffuse ferroelectric phase transition (DPT) around 360K in agreement with the X-ray measurements. We studied the evolution of Raman spectra with temperature to understand the nature of phase transition in BaTiO3 (BTO) and the BCTZO. The results indicates that the transition of ferroelectric–paraelectric state is not sharp as in the case of BTO and the polar state persists through the paraelectric state. In general, our study indicates that there are ferroelectric domains of nanometer size beyond the commonly defined transition temperature. The observation of local piezoelectric hysteresis loop indicated the existence of intrinsic ferroelectric property of the ceramic at the nanoscale. The ceramics exhibited electric field tunable dielectric properties with a tunability of 82% at an applied DC field of 40kVcm−1, low dielectric loss of 0.001 and room temperature pyroelectric coefficient of 6×10−8Ccm−2K−1 and the detectivity of 1.9×10−8Ccm−1J−1; larger than those reported for other BaTiO3-based materials. Overall, our results indicate that BCTZO ceramics with coexistence of rhombohedral–tetragonal phases is a promising candidate for lead-free ferroelectric applications.

Ferroelectric properties of BiFeO3 nanodots shattered by atomic force microscope

Abstract A BiFeO3 (BFO) nanodot was deposited on a Nb-doped SrTiO3 substrate by dip-pen nanolithography. The BFO nanodot had a diameter of about 50 nm after drying and annealing to remove the solvent contained in the nanodot. To make nanoparticles smaller than a few tens of nanometers, the BFO nanodot was then shattered using an atomic force microscope. Ferroelectric BFO nanodots smaller than 20 nm in diameter were successfully fabricated after the annealing process. A ferroelectric BFO nanodot smaller than 15 nm exhibited good ferroelectric properties with a canonical piezoelectric hysteresis loop and tunneling currents depending on ferroelectric polarizations.

Transition from Nanorod to Nanotube of Poly(vinylidene trifluoroethylene) Ferroelectric Nanofiber

The nanorod-to-nanotube transition of a piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) nanofiber inside cylindrical nanopores (CNP) with various pore diameters was precisely determined. After infiltrating the polymer into the CNP, a solid nanorod or hollow nanotube was obtained depending on the relative magnitude of the CNP diameter used compared to the critical pore diameter. The thickness of the lamellae formed inside the solid nanorod was found to be linearly dependent on the diameter of the nanocylinder. In addition, the wall thickness of the polymer nanotube increased with increasing nanocylinder diameter. The dependence of ferroelectric properties of the P(VDF–TrFE) nanofiber on the morphological transition were evaluated by measuring the piezoelectric polarization hysteresis loops. Compared to the hollow nanotube, the solid P(VDF–TrFE) nanorod showed significantly enhanced maximum polarization behavior, which is desirable for ferroelectric applications. These results show...

A Generalized Inertial-Dependent Prandtl-Ishlinskii Model for Wide-Band Frequency Piezoelectric Actuator

Smart materials such as piezoceramics used in industrial applications, are subjected to nonlinear phenomenon of hysteresis which degrades the tracking performance of the actuator in operation. Depending on the operating frequency and input magnitude applied to the piezoelectric actuators (PA), the symmetric and asymmetric hysteresis loops can be observed. A generalized inertial-dependent Prandtl-Ishlinskii (PI) model is proposed in term of the stop operator to compensate the effects of nonlinearity in asymmetric hysteresis loops for PA. A nonlinear envelope function is assigned for the threshold of the stop operator to minimize the error between the model response and the measured response obtained through the experiments at frequency range from 200 Hz to 500 Hz.

Nanoscale piezoresponse and magnetic studies of multiferroic Co and Pr co-substituted BFO thin films

Piezoresponse Force Microscopy (PFM) technique has been employed to acquire out-of-plane (OPP) piezoresponse images and local piezoelectric hysteresis loop in rhombohedrally distorted Bi1−xPrxFe1−yCoyO3 [x=0, 0.05; y=0.05] polycrystalline thin films fabricated via chemical solution deposition method. PFM images revealed that piezoelectric contrast is dependent upon the film composition. Furthermore, negative self-polarization effect was observed in the cobalt substituted BFO film. Well saturated local piezo-hysteresis loops were monitored and an increase was noticed in the piezoelectric coefficient (d33) value with cobalt doping (25.1pm/V) whereas with Pr co-substitution in BFCO film, the piezoelectric behavior was almost suppressed. Pr and cobalt co-substituted film exhibited the lowest leakage current density. Magnetic behavior (M–H curves) exhibited nearly eight times enhancement in the saturation magnetization values in the Co- and Co–Pr substituted films. The present study provides the different elements’ substitution effect on the local piezoelectric and magnetic properties of BiFeO3 multiferroic thin film.