Total Polarization Research Articles

Superhydrophobic films-based nonanyl carboxy methylcellulose grafted polyacrylamide for AISI-stainless steel corrosion protection: Empirical explorations and computational models

The current work offers an alternate environmental and facile technique to fabricate a thin coating based on the superhydrophobic film of Nonanyl carboxy methylcellulose grafted polyacrylamide (NCMC-g-PAAm-SB) which could be applied as protective layers for AISI-stainless steel corrosion. FTIR and FESEM apparatuses were used to characterize the synthesized NCMC-g-PAAm-SB. Furthermore, water uptake measurements were tested to prove the hydrophobicity character of NCMCPAAm. The thermal permanence of the NCMC-g-PAAm-SB was detected by thermo-gravimetric examination (TGA) display thermal steadiness up to 250 °C. The anticorrosive performance of the pristine and coated AISI-steel was estimated in a combination of diverse chloride solution, 3.5% NaCl + 1.0 M HCl. PDP, EIS, and potential-time experiments were performed to assess the corrosion protection features. Moreover, LPR corrosion rate tests were completed for the long-term to determine the stability of coating films in the corrosive medium. The impact of the film thickness (number of coating layers) on the corrosion characteristics was inspected. The total polarization resistance increased to 1560.3 Ω cm2 for AISI-steel coated with the NCMC-g-PAAm-SB five layers compared to 55.8 Ω cm2 for pristine AISI-steel, displayed outstanding anticorrosion behavior with 96.4% of protection capacity. FESEM was utilized to describe the surface topology of the uncoated and coated AISI-steel samples before and after exposure in the aggressive medium. The computational models were accomplished to extremely examine the corrosion protection coating mechanism of AISI-steel. Owing to their remarkable physicochemical characteristics, such superhydrophobic films are an economically and innovative accessible substitute to progress the stainless of AISI-steel corrosion resistance and can be utilized in steel protection in acidic chloride environments.

Quantum dynamics of disordered arrays of interacting superconducting qubits: Signatures of quantum collective states

We study theoretically the collective quantum dynamics occurring in various interacting superconducting qubits arrays (SQAs) in the presence of a spread of individual qubit frequencies. The interaction is provided by mutual inductive coupling between adjacent qubits (short-range Ising interaction) or inductive coupling to a low-dissipative resonator (long-range exchange interaction). In the absence of interaction the Fourier transform of temporal correlation function of the total polarization ($z$-projection of the total spin), i.e. the dynamic susceptibility $C(\omega)$, demonstrates a set of sharp small magnitude resonances corresponding to the transitions of individual superconducting qubits. We show that even a weak interaction between qubits can overcome the disorder with a simultaneous formation of the collective excited states. This collective behavior manifests itself by a single large resonance in $C(\omega)$. In the presence of a weak non-resonant microwave photon field in the low-dissipative resonator, the positions of dominant resonances depend on the number of photons, i.e. the collective ac Stark effect. Coupling of an SQA to the transmission line allows a straightforward experimental access of the collective states in microwave transmission experiments and, at the same time, to employ SQAs as sensitive single-photon detectors.

Sr Substituted La2−xSrxNi0.8Co0.2O4+δ (0 ≤ x ≤ 0.8): Impact on Oxygen Stoichiometry and Electrochemical Properties

Lanthanide nickelate Ln2NiO4+δ (Ln = La, Pr, or Nd) based mixed ionic and electronic conducting (MIEC) materials have drawn significant attention as an alternative oxygen electrode for solid oxide cells (SOCs). These nickelates show very high oxygen diffusion coefficient (D*) and surface exchange coefficient (k*) values and hence exhibit good electrocatalytic activity. Earlier reported results show that the partial substitution of Co2+ at B-site in La2Ni1−xCoxO4+δ (LNCO) leads to an enhancement in the transport and electrochemical properties of the material. Herein, we perform the substitution at A-site with Sr, i.e., La2−xSrxNi0.8Co0.2O4+δ, in order to further investigate the structural, physicochemical, and electrochemical properties. The structural characterization of the synthesized powders reveals a decrease in the lattice parameters as well as lattice volume with increasing Sr content. Furthermore, a decrease in the oxygen over stoichiometry is also observed with Sr substitution. The electrochemical measurements are performed with the symmetrical half-cells using impedance spectroscopy in the 700–900 °C temperature range. The total polarization resistance of the cell is increased with Sr substitution. The electrode reaction mechanism is also studied by recording the impedance spectra under different oxygen partial pressures. Finally, the kinetic parameters are investigated by analyzing the impedance spectra under polarization. A decrease in exchange current density (i0) is observed with increasing Sr content.

Electrochemical Impedance Spectroscopy of PEO-LATP Model Multilayers: Ionic Charge Transport and Transfer.

Solid-state batteries are seen as a possible revolutionary technology, with increased safety and energy density compared to their liquid-electrolyte-based counterparts. Composite polymer/ceramic electrolytes are candidates of interest to develop a reliable solid-state battery due to the potential synergy between the organic (softness ensuring good interfaces) and inorganic (high ionic transport) material properties. Multilayers made of a polymer/ceramic/polymer assembly are model composite electrolytes to investigate ionic charge transport and transfer. Here, multilayer systems are thoroughly studied by electrochemical impedance spectroscopy (EIS) using poly(ethylene oxide) (PEO)-based polymer electrolytes and a NaSICON-based ceramic electrolyte. The EIS methodology allows the decomposition of the total polarization resistance (Rp) of the multilayer cell as being the sum of bulk electrolyte (migration, Rel), interfacial charge transfer (Rct), and diffusion resistance (Rdif), i.e., Rp = Rel + Rct + Rdif. The phenomena associated with Rel, Rct, and Rdif are well decoupled in frequencies, and none of the contributions is blocking for ionic transport. In addition, straightforward models to deduce Rel, Rdif, and t+ (cationic transference number) of the multilayer based on the transport properties of the polymer and ceramic electrolytes are proposed. A kinetic model based on the Butler–Volmer framework is also presented to model Rct and its dependency with the polymer electrolyte salt concentration (CLi+). Interestingly, the polymer/ceramic interfacial capacitance is found to be independent of CLi+.

Using Feature-Assisted Machine Learning Algorithms to Boost Polarity in Lead-Free Multicomponent Niobate Alloys for High-Performance Ferroelectrics.

To expand the unchartered materials space of lead‐free ferroelectrics for smart digital technologies, tuning their compositional complexity via multicomponent alloying allows access to enhanced polar properties. The role of isovalent A‐site in binary potassium niobate alloys, (K,A)NbO3 using first‐principles calculations is investigated. Specifically, various alloy compositions of (K,A)NbO3 are considered and their mixing thermodynamics and associated polar properties are examined. To establish structure‐property design rules for high‐performance ferroelectrics, the sure independence screening sparsifying operator (SISSO) method is employed to extract key features to explain the A‐site driven polarization in (K,A)NbO3. Using a new metric of agreement via feature‐assisted regression and classification, the SISSO model is further extended to predict A‐site driven polarization in multicomponent systems as a function of alloy composition, reducing the prediction errors to less than 1%. With the machine learning model outlined in this work, a polarity‐composition map is established to aid the development of new multicomponent lead‐free polar oxides which can offer up to 25% boosting in A‐site driven polarization and achieving more than 150% of the total polarization in pristine KNbO3. This study offers a design‐based rational route to develop lead‐free multicomponent ferroelectric oxides for niche information technologies.

Symmetry Constraints on Spin Order Transfer in Parahydrogen-Induced Polarization (PHIP)

It is well known that the association of parahydrogen (pH2) with an unsaturated molecule or a transient metalorganic complex can enhance the intensity of NMR signals; the effect is known as parahydrogen-induced polarization (PHIP). During recent decades, numerous methods were proposed for converting pH2-derived nuclear spin order to the observable magnetization of protons or other nuclei of interest, usually 13C or 15N. Here, we analyze the constraints imposed by the topological symmetry of the spin systems on the amplitude of transferred polarization. We find that in asymmetric systems, heteronuclei can be polarized to 100%. However, the amplitude drops to 75% in A2BX systems and further to 50% in A3B2X systems. The latter case is of primary importance for biological applications of PHIP using sidearm hydrogenation (PHIP-SAH). If the polarization is transferred to the same type of nuclei, i.e., 1H, symmetry constraints impose significant boundaries on the spin-order distribution. For AB, A2B, A3B, A2B2, AA’(AA’) systems, the maximum average polarization for each spin is 100%, 50%, 33.3%, 25%, and 0, respectively, (where A and B (or A’) came from pH2). Remarkably, if the polarization of all spins in a molecule is summed up, the total polarization grows asymptotically with ~1.27N and can exceed 2 in the absence of symmetry constraints (where N is the number of spins). We also discuss the effect of dipole–dipole-induced pH2 spin-order distribution in heterogeneous catalysis or nematic liquid crystals. Practical examples from the literature illustrate our theoretical analysis.

A Quantitative Estimation of the Behaviour of Unsaturated Lipid Molecular Species During Their Argentation Liquid Chromatographic Separation

Background: Analysis of experimental retention data upon several variants of argentation liquid chromatographic separations of different mixtures of the same lipid class into their molecular species was made to estimate new parameters of their π-complexes for every unsaturated fatty acid residue as its silver ion cluster. Methods: Planar reversed-phase liquid chromatography, both in the presence and absence of silver ions as well as adsorption argentation liquid chromatography was applied for the separation of complex rac-1,2-diacylglycerol samples from three plant sources (cocoa butter, poppy seed, and linseed oils). Results: Every value of the argentation liquid chromatographic separation selectivity for any lipid molecular species upon both planar and column variants of reversed-phase fractionation of different complex samples from native sources into their molecular components is described by additive relative polarity levels of their fatty acid residues. These levels are always connected with equivalent lipophilicity values for every lipid molecule and its potential chemical variations during all variants of reversed-phase liquid chromatography in the presence of silver ion clusters. Conclusion: New parameters for several fatty acid residues of major native polyunsaturated lipid samples may be reflected by different coordination numbers of single silver atoms of its triangular pyramidal nanoclusters. Both hydrophobicity and total polarity levels of the coordination complexes of different lipid molecular species upon their adsorption argentation liquid chromatography may also be quantitatively estimated by their fixed methylene unit variations of these molecular species for two centigrade lipid scales.

Coronal Cavities in CoMP Observations

Abstract Quiescent coronal cavities can provide insight into solar magnetic fields. They are observed in the coronal emission lines in both polarized and unpolarized light. In the total linear polarization fraction (L/I), they often possess a “lagomorphic,” or “rabbit-shaped,” structure that reflects the underlying magnetic field configuration. We studied quiescent coronal cavities observed between 2012 and 2018 by the Coronal Multichannel Polarimeter (CoMP). The majority of cavities in our study had a characteristic lagomorphic structure in linear polarization. We additionally compared cavity widths as observed in intensity with sizes of their linear polarization signatures for 70 cavities and found that both features are strongly correlated. Our results indicate that chances for observing a lagomorphic structure increase greatly with cavity lifetime, suggesting that the visibility depends on the spatial orientation of the cavity. Forward-modeled observations in linear polarization of flux ropes confirmed this assumption. We conclude that observations of the solar coronal cavities in linear polarization are consistent with the theoretical model of flux rope formation and structure.

Modeling the Spectral Energy Distributions and Spectropolarimetry of Blazars—Application to 4C+01.02 in 2016–2017*

Abstract The optical radiation emitted by blazars contains contributions from synchrotron radiation by relativistic electrons in the jets, as well as thermal radiation emitted mainly by the accretion disk (AD), the broad-line region (BLR), and the host galaxy. The unpolarized radiation components from the AD, BLR, and host galaxy present themselves by decreasing the total polarization in the optical/ultraviolet (UV) spectrum. A combined model for the spectral energy distribution (SED) and degree of optical/UV polarization is constructed, enabling the disentanglement of the synchrotron and AD components. Our model is applied to the multiwavelength SED and spectropolarimetry observations of the flat-spectrum radio quasar 4C+01.02 (z = 2.1) in its 2016 July–August flaring state and 2017 July–August quiescent state, using data from the Fermi Large Area Telescope, the Southern African Large Telescope, and the Las Cumbres Observatory network of telescopes. By constraining the AD component, the mass of the supermassive black hole is obtained as ∼3 × 109 M ⊙. Furthermore, the model retrieves the characteristics of the relativistic electron distribution in the jet and the degree of ordering of the magnetic field. Our results highlight the potential of spectropolarimetry observations for disentangling thermal from nonthermal (jet) emission components, thus revealing the physics of particle acceleration and high-energy emission in active galactic nucleus jets.

Crystalline texture analyses of sputtered BiFeO3 thick films on Si with a large polarization

In our work last year (H. Zhu et al., Rhombohedral BiFeO 3 thick films integrated on Si with a giant electric polarization and prominent piezoelectricity, Acta Materialia 200 (2020) 305–314), it was demonstrated that the rhombohedral-like, (110)-textured BiFeO 3 thick films (∼2 μm) sputter-deposited at 450 °C and 500 °C exhibited ultrahigh polarizations of P r ∼ 115 μC/cm 2 and 135 μC/cm 2 , respectively. However, it is not sufficient to explain these ultra-high polarizations by a preferential growth mechanism and the effect of a moderate compressive strain. To further clarify the polarization enhancement of the films, the texture characteristics of these BFO thick films were quantitatively analyzed by fitting the rocking curves and pole figures to the March-Dollase model. The results showed that, in addition to the (110)-textured growth of a BFO thick film under a moderate compressive strain, the minority non-(110)-textured grains also contributed to the enhancement of the total polarization. Our study demonstrates that, the ultra-high polarizations of our BFO thick films can be well explained by adding the contribution from non-textured grains to the preferential growth of the film under a compressive strain. • (110)- and (100)-textured BFO thick films were sputtered deposited on platinized Si substrates. • The films’ texture chracteristics were quantitatively analyzed based on the March-Dollase fuction. • The contributions of textured and non-textured grains to polarization enhancement were mainly discussed. • An achievement of unusually large polarization of BFO thick film can be well explained.

Development and application of metamaterial-based half-wave plates for the NIKA and NIKA2 polarimeters

Context.Large field-of-view imaging and polarimetry instruments operating at millimetre and sub-millimetre wavelengths are fundamental tools to understand the role of magnetic fields in channelling filament material into prestellar cores, providing unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarisation observations of Active Galactic Nuclei (AGNs) will allow us to constrain the possible physical conditions of the emitting plasma from the jets and/or explore the physics of dust inside supernova remnants. The kilo-pixel New IRAM KIDs Array 2 (NIKA2) camera, installed today at the Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope, represents one of the best tools available to astronomers to produce simultaneous intensity and polarimetry maps over large fields at 260 GHz (1.15 mm).Aims.The polarisation measurement, in NIKA and NIKA2, is achieved by rapidly modulating the total incoming polarisation. In the end, this allows one to safely isolate the small science signal from the large, un-polarised, and strongly variable, atmospheric background.Methods.The polarisation modulation is achieved by inserting a fast rotating half-wave plate (HWP) in the optical beam. In order to allow wide field-of-view observations, the plate has to be large, with a diameter of 250 mm. The modulation of the polarised signal at 12 Hz also requires the waveplate to be sufficiently light. In addition, this key optical element has to exhibit optimal electromagnetic characteristics in terms of transmission and differential phase-shift. For this purpose, three metamaterial HWPs have been developed using the mesh-filter technology. The knowledge acquired in developing the first two single-band HWPs was used to achieve the more challenging performance requirements of the last dual-band HWP. The first and the third waveplates met the requirements for both the NIKA and NIKA2 instruments.Results.We first illustrate the design, the technical developments, the fabrication, and laboratory characterisation of the three mesh-HWPs. The deployment of two such elements in the NIKA and NIKA2 instruments at the 30-metre telescope is then described. We conclude with representative examples of astrophysical maps integrating polarimetry.

Efficiency and Forward Voltage of Blue and Green Lateral LEDs with V-shaped Defects and Random Alloy Fluctuation in Quantum Wells

For nitride-based blue and green light-emitting diodes (LEDs), the forward voltage $V_\text{for}$ is larger than expected, especially for green LEDs. This is mainly due to the large barriers to vertical carrier transport caused by the total polarization discontinuity at multiple quantum well and quantum barrier interfaces. The natural random alloy fluctuation in QWs has proven to be an important factor reducing $V_\text{for}$. However, this does not suffice in the case of green LEDs because of their larger polarization-induced barrier. V-defects have been proposed as another key factor in reducing $V_\text{for}$ to allow laterally injection into multiple quantum wells (MQWs), thus bypassing the multiple energy barriers incurred by vertical transport. In this paper, to model carrier transport in the whole LED, we consider both random-alloy and V-defect effects. A fully two-dimensional drift-diffusion charge-control solver is used to model both effects. The results indicate that the turn-on voltages for blue and green LEDs are both affected by random alloy fluctuations and V-defect density. For green LEDs, $V_\text{for}$ decreases more due to V-defects, where the smaller polarization barrier at the V-defect sidewall is the major path for lateral carrier injection. Finally, we discuss how V-defect density and size affects the results.

Deep ultraviolet spectra from BGaN quantum dot structures

This work theoretically studies boron-containing ternary and quaternary lattice-matched quantum dot (QD) structures that emit ultraviolet (UV) wavelength by varying the boron mole fraction in the QD active region or the barrier. For BGaN and BAlGaN QD structures, matching to AlN, BAlN, AlGaN barriers and also BInGaN/AlN, the wide-bandgap AlN barrier imposes them to emit at 198–202 nm wavelength. For BInGaN QDs matching to the AlGaN, BAlN, the situation is different. They can emit at the range 252−291nm depending on the barrier and the efficiency of boron content in the barrier in redshifting the wavelength is deduced. The TE and TM gain and spontaneous emission spectra are high and increase under increasing boron in the active region or reducing boron content in the barrier region, exceeding its quantum-well counterpart and of central importance in light-emitting diode applications. Ultra-high gain is obtained from BInGaN/BAlN structure. Gain values are arranged according to the bandgap difference (ΔEg). The range of ΔEg is extended, in the studied structures, to ΔEg=1866−2856 meV, which is of practical importance in UV device applications. The total polarization is decreasing for the Al-containing systems, which is preferred.

Ionic Control over Ferroelectricity in 2D Layered van der Waals Capacitors.

The van der Waals layered material CuInP2S6 features interesting functional behavior, including the existence of four uniaxial polarization states, polarization reversal against the electric field through Cu ion migration, a negative-capacitance regime, and reversible extraction of Cu ions. At the heart of these characteristics lies the high mobility of Cu ions, which also determines the spontaneous polarization. Therefore, Cu migration across the lattice results in unusual ferroelectric behavior. Here, we demonstrate how the interplay of polar and ionic properties provides a path to ionically controlled ferroelectric behavior, achieved by applying selected DC voltage pulses and subsequently probing ferroelectric switching during fast triangular voltage sweeps. Using current measurements and theoretical calculations, we observe that increasing DC pulse duration results in higher ionic currents, the buildup of an internal electric field that shifts polarization loops, and an increase in total switchable polarization by ∼50% due to the existence of a high polarization phase which is stabilized by the internal electric field. Apart from tuning ferroelectric behavior by selected square pulses, hysteretic polarization switching can even be entirely deactivated and reactivated, resulting in three-state systems where polarization switching is either inhibited or can be performed in two different directions.

Electrical conduction of PMMA/PLA doped lithium bis(oxalato) borate based hybrid gel polymer electrolyte

The present work highlights the investigation of electrical conduction properties of gel polymer electrolyte (GPE) based poly(methyl) methacrylate (PMMA) and poly(lactic) acid (PLA) blend doped with various compositions of lithium bis(oxalato) borate. The impedance analysis revealed the GPE systems exhibit maximum ionic conductivity of 1.37 × 10−3 S cm−1 for sample PLi20. The electrical properties based on the dielectric permittivity of entire samples decreased with increasing frequency and followed the trend of ionic conductivity. Further analysis was carried out to determine the dielectric response at different temperatures, focusing on the most conducting sample (PLi20). Both dielectric constant and loss increase with the increasing temperature, which suggested that total polarization has occurred. In conclusion, the samples with 20 wt% composition of LiBOB exhibit the highest conducting properties which significantly provides good electrical performance for the application in energy storage devices.

Nano-LaCoO3 infiltrated BaZr0.8Y0.2O3− electrodes for steam splitting in protonic ceramic electrolysis cells

Protonic ceramic electrolysis cell (PCEC) is a promising technology for production of pure dry hydrogen due to the low operating temperature and high efficiency. One of the obstacles for commercialization of PCEC technology is the poor performance and insufficient long-term durability of the oxygen electrode. In this study, we address the above challenge by designing a LaCoO3 (LC) catalyst infiltrated porous BaZr0.8Y0.2O3−δ (BZY20) backbone electrode (LC-BZY20). The performance and durability of the LC-BZY20 electrode are investigated on symmetrical cells using electrochemical impedance spectroscopy (EIS). The total electrode polarization resistance (RP) values of the electrode are 0.56, 1.24, 2.18, and 2.90 Ω cm2 in 3 ​vol% humidified synthetic air at 600, 550, 500, and 450 ​°C, respectively, indicating good electrochemical performance of the LC-BZY20 electrode. Furthermore, the LC-BZY20 electrode displays good stability, without significant performance degradation when tested at 600 ​°C in 10 ​vol% humidified air for 900 ​h. We further study the influence of oxygen partial pressure (Po2) and steam partial pressure (PH2O) on the response of the EIS data, and propose a set of chemical and electrochemical processes involved in the steam splitting reaction in the LC-BZY20 electrode.

Exsolution in La and Ni co-doped strontium titanate: a suitable anode for running SOFCs on ammonia as alternative fuel

Ammonia exhibits interesting features as fuel to feed Solid Oxide Fuel Cell. Herein, Ni and La co-doped strontium titanate was synthetized using wet chemistry route. Ni nanoparticles emerged via exsolution in reducing environment to decorate the surface. X-Ray Diffraction measurements exhibits perovskite structure was also preserved after the exsolution, as expected. H2 – Temperature Programmed Reduction highlights the great resistance of titanates in anode operation condition. Ammonia conversion in nitrogen and hydrogen were investigated by catalytic tests. It begins to decompose at 560°C and the full yield was achieved at 720°C. Electrochemical measurements were recorded at 800°C using 10% of ammonia in Ar. They were analysed though the model of equivalent circuit and two processes were attributed. Results certify Ni exsolution strongly enhances the hydrogen oxidation and the total polarisation resistance in ammonia approaches to the one in hydrogen.

Whither Steady-State Negative Capacitance of a Ferroelectric Film?

We theoretically explore mechanisms that can potentially give rise to steady-state negative capacitance in a uniaxial ferroelectric film stabilized by a dielectric layer. The analytical expressions for the steady-state capacitance of a single-domain state are derived within Landau-Ginzburg-Devonshire approach and used to study the state stability vs. the domain splitting as a function of dielectric layer thickness. Analytical expressions for the critical thickness of the dielectric layer, polarization amplitude, equilibrium domain period and susceptibility are obtained and corroborated by finite element modelling. In the absence of screening charges neither single-domain, nor poly-domain states can exhibit globally-detectable steady-state negative capacitance. We further explore the possible effects of nonlinear screening at the ferroelectric-dielectric interface and show that if at least one of the screening charges is very slow, the total polarization dynamics can exhibit complex time- and voltage dependent behaviors that can be interpreted as a negative capacitance. In this setting, the negative capacitance effect is accompanied by almost zero dielectric susceptibility in a wide voltage range and low frequencies. These results may help to elucidate the fundamental dispute about the possible origin of the quasi-steady-state negative capacitance in thin ferroelectric films, and identify materials systems that can give rise to this behavior.

Domain Dynamics and Local Level Switching Behaviors of Sol–Gel Nanopowder-Derived Lead-Free Piezoelectric Bi0.5(Na0.78K0.22)0.5TiO3 Ceramics

The material properties of sol–gel nanopowder-derived lead-free Bi0.5(Na0.78K0.22)0.5TiO3 (BNKT) ceramics are systematically investigated for high-response piezoelectric device applications. To elucidate the principle of the domain dynamics and local level ferroelectric switching behaviors of environmentally friendly BNKT ceramics, we systematically analyze the Rayleigh parameters and the first-order reversal curve (FORC) of the BNKT ceramics and compare the results with those of the standard measurement method. Based on the characterization of Rayleigh parameters, it is clarified that the contribution of the domain-wall motion of the sol–gel-derived BNKT ceramics is higher than that of solid-state reaction-derived ceramics. We also analyze the FORC distribution diagram-associated hysteron density functions for visualizing reversible and irreversible contributions of domain walls and switching behaviors above the Rayleigh regime. The switching behaviors are explained by considering the defects and microstructural differences of the BNKT ceramics, which are affected by both reversible and irreversible contributions. The sol–gel-derived BNKT ceramics show highly localized and well-defined FORC distribution diagrams with the sharp maximum of the irreversible component and the low reversible contribution, which clearly indicate more homogeneous switching properties and less defects than solid-state reaction-derived ceramics because each switching unit gives almost identical contributions to the total polarization. In this study, the developed technique and gained information are used to explore a fundamental understanding of the domain dynamics and local level switching behaviors of lead-free piezoelectric ceramics. We believe that our investigation certainly positions itself in various multifunctional electronic applications without using toxic lead-based piezoelectrics.

Purity of 3D polarization.

Measures of purity for 3D partially polarized fields, and in particular, the separation into circularly and linearly polarized contributions, are reexamined, and a new degree of total linear polarization introduced. Explicit expressions for the characteristic decomposition in terms of coherency matrix elements are presented, including the special case of an intrinsic coherency matrix. Parameterization of the coherency matrix in terms of ellipticity, and the directions of the ellipse normal and major axis are investigated. Phase consistency is discussed. A comprehensive collection of results regarding intrinsic polarization properties is presented.