Irreversible Domain Wall Motion Research Articles

Rayleigh analysis of domain dynamics across temperature induced polymorphic phase transitions in lead-free piezoceramics (1−x)(BaTi0.88Sn0.12)–x(Ba0.7Ca0.3)TiO3

We carried out a Rayleigh analysis of the dielectric permittivity of a lead-free piezoceramic system (1−x)(BaTi0.88Sn0.12)–x(Ba0.7Ca0.3)TiO3 across the composition and temperature induced polymorphic phase transformations to determine the trend in the reversible and irreversible domain wall motion across the composition and temperature induced structural changes. Experiments were carried out on three representative compositions x = 0.10, 0.2, and 0.25 exhibiting rhombohedral, orthorhombic, and tetragonal phases at room temperature. While confirming that the irreversible Rayleigh parameter is large in the orthorhombic phase, we discuss a correspondence between the reduction in the coercive field and the corresponding increase in the irreversible Rayleigh parameter. We also show how the proximity of the Curie point to the polymorphic phase boundary greatly undermines this correspondence.

Results of magnetometry data processing for non-destructive testing of compressive mechanical stress levels in steels

We plotted the fields of measurement coil signal as functions inversely proportional to reversible magnetisation in low-carbon St20 steel plates subjected to plastic tensile strain. Performing an additional approximation of our experimental data using three pseudo-Voigt functions allowed us to detect the information concerning irreversible motion of the 90-degree domain walls that are most sensitive to mechanical stresses. As a result of performing mathematical processing of experimental data we managed to improve validity of estimating the fields of stress-induced magnetic anisotropy and mechanical stresses.

Evaluation of domain wall motion in Mn-doped PMS-PZT ceramics under various hydrostatic pressures by nonlinear response measurements

The nonlinear dielectric responses of both unpoled and poled Mn-doped PMS-PZT ceramics as a function of hydrostatic pressure were investigated. Based on the application of Rayleigh law analysis, the contribution of irreversible domain wall motion to the dielectric response under hydrostatic pressure was quantitatively evaluated. Initial increased irreversible extrinsic contribution to the dielectric responses were observed in both unpoled and poled samples which can be ascribed to the pressure induced domain wall pinning relaxation effect. In addition, the pressure induced depolarization effect may also facilitate domain related extrinsic contribution to dielectric response in poled samples. The present study may shed further light on understanding the domain wall motion dynamic in piezoelectric ceramics under the application of hydrostatic pressure and is quite helpful for the design and optimization of piezoelectric devices used in underwater areas.

Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

Lead-free Ca, Zr co-doped BaTiO3 (BCZT) single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The <001> oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

Magnetic force microscopy studies in bulk polycrystalline iron

The paper presents magnetic force microscopy (MFM) studies on the effect of crystallographic orientation and external magnetic field on magnetic microstructure in a bulk polycrystalline iron specimen. The magneto crystalline anisotropic effect on the domain structure is characterized with the support of electron backscatter diffraction study. The distinct variations in magnetic domain structure are observed based on the crystallographic orientation of the grain surface normal with respect to the cube axis i.e. the easy axis of magnetization. Further, the local magnetization behavior is studied in-situ by MFM in presence of external magnetic field in the range of −2000 to 2000Oe. Various micro-magnetization phenomena such as reversible and irreversible domain wall movements, expansion and contraction of domains, Barkhausen jump, bowing of a pinned domain wall and nucleation of a spike domain are visualized. The respective changes in the magnetic microstructure are compared with the bulk magnetization obtained using vibrating sample magnetometer. Bowing of a domain wall, pinned at two points, upon application of magnetic field is used to estimate the domain wall energy density. The MFM studies in presence of external field applied in two perpendicular directions are used to reveal the influence of the crystalline anisotropy on the local micro-magnetization.

Electrophysical properties of matrix composites nanocrystalline cellulose – triglycine sulfate

ABSTRACTDielectric dispersion for a composite based on nanocrystalline cellulose with triglycine sulfate in the frequency range from 1 mHz to 1 kHz at different temperatures from room temperature to the phase transition temperature of the composite (∼ +54°C) in a weak measuring field (1 V·cm−1) was investigated. The obtained results showed the presence of two relaxation regions: the characteristic for the bulk of triglycine sulfate linear dielectric dispersion (10 Hz – 1 kHz) associated with the irreversible motion of domain walls and a significant dispersion region at lower frequencies from 1 mHz to 10 Hz related to the Maxwell-Wagner-Sillars interfacial polarization.

Correlation between piezoresponse nonlinearity and hysteresis in ferroelectric crystals at the nanoscale

The nonlinear response of a ferroic to external fields has been studied for decades, garnering interest for both understanding fundamental physics, as well as technological applications such as memory devices. Yet, the behavior of ferroelectrics at mesoscopic regimes remains poorly understood, and the scale limits of theories developed for macroscopic regimes are not well tested experimentally. Here, we test the link between piezo-nonlinearity and local piezoelectric strain hysteresis, via AC-field dependent measurements in conjunction with hysteresis measurements with varying voltage windows on (K,Na)NbO3 crystals with band-excitation piezoelectric force microscopy. The correlation coefficient between nonlinearity amplitude and the amplitude during hysteresis loop acquisition shows a clear decrease with increasing AC bias. Further, correlation of polynomial fitting terms from the nonlinear measurements with the hysteresis loop area reveals that the largest correlations are reserved for the quadratic terms, which is expected for irreversible domain wall motion contributions that impact both piezoelectric behavior as well as minor loop formation. This study suggests applicability at local length scales of fundamental principles of Rayleigh behavior, with associated implications for future nanoscale ferroic devices.

Abnormal magnetization behaviors in Sm–Ni–Fe–Cu alloys

The magnetization behaviors in Sm–Ni–Fe–Cu alloys at low temperatures have been investigated. It was found that the hysteresis loops show wasp-waisted character at low temperatures, which has been proved to be related to the existence of multi-phases, the Fe/Ni soft magnetic phases and the CaCu5-type hard magnetic phase. A smooth-jump behavior of the magnetization is observed at T>5K, whereas a step-like magnetization process appears at T<5K. The CaCu5-type phase is responsible for such abnormal magnetization behavior. The magnetic moment reversal model with thermal activation is used to explain the relation of the critical magnetic field (Hcm) to the temperature (T>5K). The reversal of the moment direction has to cross over an energy barrier of about 6.6×10−15erg. The step-like jumps of the magnetization below 5K is proposed to be resulted from a sharp increase of the sample temperature under the heat released by the irreversible domain wall motion.

The Rayleigh law in silicon doped hafnium oxide ferroelectric thin films

A wealth of studies have confirmed that the low‐field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro‐mechanism. Recently, HfO2 thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub‐coercive polarization reversal properties were investigated for 10 nm thick Si‐doped HfO2 thin films. The applicability of the Rayleigh law to ultra‐thin ferroelectric films was first confirmed, indicating the existence of a multi‐domain structure. Since the grain size is about 20–30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (© 2015 WILEY‐VCH Verlag GmbH &amp;Co. KGaA, Weinheim)

Effect of Dy on the dielectric nonlinear behavior of Mn and V-doped BaTiO3multilayer ceramic capacitors

Abstract

PLZT film capacitors for power electronics and energy storage applications

Ceramic film capacitors with high dielectric constant and high breakdown strength hold special promise for applications demanding high power density. By means of chemical solution deposition, we deposited ≈2-μm-thick films of lanthanum-doped lead zirconate titanate (PLZT) on LaNiO3-buffered Ni (LNO/Ni) foils and platinized silicon (PtSi) substrates. The dielectric properties and energy storage performance of the resulting samples were determined under a high level of applied electric field. X-ray diffraction stress analysis revealed that PLZT on LNO/Ni bears a compressive stress of ≈370 MPa while PLZT on PtSi endures a tensile stress of ≈250 MPa. Compressive stress was found to lead to heightened polarization, improved tunability, increased irreversible domain wall motion, and enhanced breakdown strength for PLZT deposited on the LNO/Ni as compared with the PtSi substrate. We observed a tunability of ≈55 and ≈40 % at room temperature under 100 kV/cm applied field, remanent polarization of ≈23.5 and ≈7.4 µC/cm2, coercive electric field of ≈25.6 and ≈21.1 kV/cm, and dielectric breakdown strength of ≈2.6 and ≈1.5 MV/cm for PLZT deposited on LNO/Ni foils and PtSi substrates, respectively. A high recoverable energy density of ≈85 J/cm3 and energy conversion efficiency of ≈65 % were measured on the PLZT film grown on LNO/Ni.

Magnetization dynamics of FeCuNbSiB soft magnetic ribbons and derived powder cores

In this study, the different character of magnetization mechanisms in as-quenched and annealed Fe73Cu1Nb3Si16B7 ribbon and derived nanocrystalline powder cores was studied by using very useful technique known as impedance spectroscopy. We investigated the dynamics and relaxation of the reversible and irreversible domain wall movements, as the dominant magnetization processes in the samples, by means of the effects of the increasing AC magnetic field amplitude on the complex permeability in a wide frequency range. In an amorphous ribbon, which was a precursor for preparation of powder cores, we observed two well-recognizable relaxation-dispersion regions corresponding to the domain wall displacements and bulging, respectively. The similar behavior was found for the annealed ribbon sample. However, in the bulk powder cores, only one dispersion region was present. From obtained complex permeability spectra, the interesting properties of the samples connected to their domain structure, such as relaxation frequencies of stepwise extinct magnetization processes and pinning fields, were extracted. All these phenomena were extensively discussed and the corresponding results for as-quenched and annealed ribbon and prepared bulk powder cores were confront.

Domain Structure of Potassium‐Sodium Niobate Ceramics Before and After Poling

Domain structure and domain wall motion play important roles on the piezoelectric properties of ferroelectric ceramics. In this work, the domain structure of hot‐pressed (K0.50Na0.50)NbO3 (KNN) ceramics before and after poling were studied by observing the domain patterns with an acid‐etching technique, and the extrinsic contribution to the piezoelectric properties were evaluated. It was found that the domain structure of the unpoled KNN ceramic was relatively complicated with many watermark, herringbone and zigzag patterns, while only a single set or few sets of parallel domain stripes were observed in the poled KNN ceramic, due to the domain reorientation and domain wall motion during the poling process. The average domain width changes from 200 (±10) nm before poling to 250 (±10) nm after poling. Domain configurations of “Herringbone‐Zigzag‐Watermark” and “Herringbone‐ Herringbone‐Zigzag” types observed in the unpoled KNN ceramic were then further analyzed. The extrinsic contribution to the piezoelectric properties from the domain reorientation and irreversible domain wall motion in the hot‐pressed KNN ceramic was found to be 71%, slightly higher than that of conventional sintered KNN ceramics ~68%.

Rayleigh Region in Amorphous and Nanocrystaline FINEMET Alloy

Magnetization processes in ferromagnetic materials can be described in four ways, reversible and irreversible domain wall (DW) motion, rotation of the vector of magnetic polarization, and paraprocess in high magnetic elds. The process of reversible DW motion is characteristic for the range of small exciting magnetic elds the Rayleigh region (RR). The dependence of magnetic polarization J in this region, called also the region of initial susceptibility (permeability), on the magnetic eld strength H can be expressed by the following equation

Domain Contribution to Elastic Nonlinearity in Pb(Zr, Ti)O&lt;sub&gt;3&lt;/sub&gt;-Based Piezoelectric Ceramics

In order to clarify the origin of the elastic nonlinearity in piezoelectric ceramics, the effect of Mn substitution into Pb (Zr,Ti)O3-based ceramics on the nonlinear elastic stiffness was investigated by analyzing the transient response after burst excitation. The real part of 3rd-order elastic stiffness drastically decreased with increasing Mn content. It was also found that the appearance of the elastic nonlinearity enhanced the mechanical loss. From the results, the irreversible domain wall motion overcoming the potential barrier due to defect complexes was considered as a possible origin of the elastic nonlinearity.

Effect of Ni Doping on Strength and Damping Capacity of Fe–Al Alloys

Strength and damping capacity of Fe–Al alloys doped with different amounts of Ni were examined. Fe–Al alloys with an appropriate amount of Ni doping exhibited yield stress higher than 1 GPa and internal friction of above 0.032. In these alloys, the NiAl phase with the B2 structure densely precipitated in the Fe–Al matrix, satisfying the cube-on-cube orientation relationship. The precipitation of NiAl resulted in high strength, which was associated with the difference in primary slip systems between the NiAl precipitates and the Fe–Al matrix. Moreover, the internal friction measured under an external magnetic field showed low values, suggesting that Fe–Al alloys with the NiAl precipitates demonstrated magneto-mechanical damping caused by the irreversible motion of magnetic domain walls. The Al concentration in the Fe–Al matrix became appropriate for damping properties by the precipitation of NiAl, resulting in an increase in the internal friction of the alloy.

De-aging of Fe-doped lead-zirconate-titanate ceramics by electric field cycling: 180°- vs. non-180° domain wall processes

Acceptor-doped ferroelectrics tend to show pronounced aging behavior. The microscopic effects of aging are commonly related to oxygen vacancies, however, there are still open questions with respect to their impact on domain wall movements. To elucidate the latter, the reverse process of de-aging by electric field cycling is investigated here on Pb(Zr0.54Ti0.46)O3 doped with iron in different concentrations. Measurements of the hysteretic behavior of large-signal parameters, i.e., polarization and strain, as well as small-signal parameters, i.e., electrical permittivity and piezoelectric coefficient, are used to distinguish between reversible and irreversible movement of 180°- and non-180° domain walls. The results indicate that for low doping concentrations, the de-aging behavior of 180° domain wall motion is governed by irreversible domain wall motion and a coarsening of the domain structure, while for non-180° domain walls the change in reversible domain wall mobility is the dominant de-aging mechanism. For high doping concentrations, an additional clamping effect related to the smaller grain size occurs.

Magnetic hysteresis scaling behavior in terbium and holmium

Hysteresis scaling for magnetic minor loops has been examined in the heavy rare-earth metals Tb and Ho, varying the temperature and magnetic-field amplitudes. In addition to the low-temperature ferromagnetic phase below ${T}_{\mathrm{c}}$, the scaling law between the hysteresis loss and remanent flux density with an exponent of $\ensuremath{\sim}$1.3 was observed in the higher-temperature helical antiferromagnetic phase for both metals. The coefficient which reflects the pinning fields of the domain walls decreases with increasing temperature below ${T}_{\mathrm{c}}$, but it exhibits a sharp increase after the onset of the helical antiferromagnetic phase. The observations above ${T}_{\mathrm{c}}$ were explained as due to the irreversible motion of spiral domain walls, unlike the 180${}^{\ensuremath{\circ}}$ Bloch walls that are typical in the ferromagnetic phase.

Domain size engineering in tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals

The effect of domain size on the dielectric and piezoelectric properties of [111]-oriented tetragonal Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) crystals was investigated. The dielectric permittivity (ɛ(33 ) (T)∕ɛ(0)) and piezoelectric coefficient (d(33)) were found to be on the order of 13 800 and 1630 pC∕N, respectively, for samples with domain size of ∼500 nm, a 3-fold increase to crystals with domain size of ∼50 μm. Rayleigh analysis revealed that the extrinsic contribution to the piezoelectric response increased from ∼8% to 30% with decreasing domain size, due to the increased domain wall density and associated irreversible domain wall motion. The enhanced properties were thought to relate to the fine domain structures, however, showing a poor electric field and temperature stabilities with domain size of 500 nm. Of particular significance is that samples with domain size being on the order of 5 μm exhibit field and temperature stabilities, with yet high piezoelectric properties, make it potential for transducer applications.

Temperature and frequency characteristics of low-loss MnZn ferrite in a wide temperature range

A low-loss Mn0.7Zn0.24Fe2.06O4 ferrite has been prepared by a solid-state reaction method. The MnZn ferrite has a high initial permeability, μi (3097), a high saturation induction, Bs (526 mT), a high Curie temperature, Tc (220 °C), and a low core loss, PL (≤ 415 kW/m3) in a wide temperature (25–120 °C) and frequency (10–100 kHz) range. As the temperature increases, an initial decrease followed by a subsequent increase of hysteresis loss, Ph, and eddy current loss, Pe is observed. Both Ph and Pe increase with increasing frequency. When f ≥ 300 kHz, a residual loss, Pr, appears. Pe increases with increasing temperature and frequency. The temperature and frequency dependence of Ph can be explained by irreversible domain wall movements, Pe by the skin effect, and Pr by domain wall resonance, respectively.