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Ferroelectric tunnel junction (FTJ) is considered one of the promising emerging non-volatile memories. In recent years, the development of freestanding ferroelectric has provided greater freedom for the preparation and performance control of FTJs. In this work, we prepared a series of PbTiO₃ freestanding ferroelectrics with different thicknesses and successfully transferred them to Nb:SrTiO₃ or Si substrates to prepare tunnel junction devices. The structure of the freestanding ferroelectrics was characterized by X-ray diffraction and transmission electron microscopy, confirming the high quality of the ferroelectric before and after the transfer and the existence of structural distortion. Based on piezoelectric force response microscopy and macroscopic electrical measurements, the domain switching and electrical properties of the FTJ were carefully characterized. The ON/OFF ratio of the prepared freestanding FTJ was as high as 10⁸, and it is expected to reach 10⁶ after 10 years of retention. The mechanism behind performance differences between the freestanding FTJ and the traditional tunnel junction is analyzed. In addition, we also studied the effect of light illuminance on the performance of the freestanding FTJ.

Multiferroic Ba(Ti${}_{0.80}$Zr${}_{0.20}$)O₃-0.5(Ba${}_{0.70}$Ca${}_{0.30}$)TiO₃ (BCTZ)@CoFe₂O₄ (CFO) hybrid nanofibers (NFs) were fabricated by a sol–gel electrospinning. The perovskite structure of ferroelectric BCTZ and the spinel structure of ferromagnetic CFO coexist and are homogeneously distributed, and their interface along the perovskite [110] zone axis was directly observed. The indirect magnetoelectric (ME) coupling effect was observed from the magnetization versus temperature (M–T) curves, demonstrating a distinct singularity on the dM/dT curve near the ferroelectric Curie temperature ($T$${}_C$) of 387 K. The piezocatalytic rate of BCTZ@CFO multiferroic hybrid NF (2.6 × 10${}^{-2}$min${}^{-1}$) is higher than NP (1.9 × 10${}^{-2}$min${}^{-1}$) because the piezoelectricity of the one-dimensional (1D) multiferroic NF is higher than that of NPs, beneficial for the mechanical vibration-induced localized built-in electric fields for piezocatalysis under ultrasound.

Rare-earth elements ${\text{Sm}}^{3+}$-, ${\text{Pr}}^{3+}$-, ${\text{Ho}}^{3+}$- and ${\text{Er}}^{3+}$-doped (${\text{K}}_{0.5}$${\text{Na}}_{0.5}$)${}_{0.974}$${\text{La}}_{0.025}$${\text{Nb}}_{0.975}$${\text{Bi}}_{0.025}$O₃ ceramics (abbreviated as KNLNB-0.1%RE) were prepared by conventional solid-phase sintering method. The structure, transparency, energy storage and photoluminescence properties of the samples are investigated. All ceramics have the pseudo-cubic phase structure without the impurity phase at room temperature. KNLNB-0.1%RE ceramics exhibit excellent optical transmittance, with KNLNB-0.1%Ho achieving 71.8% transmittance in the visible wavelength range (780nm) and largest effective energy storage density of 1.45J/cm³. In our experiments, rare-earth-doped KNLNB ceramics exhibit photoluminescence effects. This work facilitates the development of transparent energy storage ceramics with fluorescent effects.

A model of a novel 1–3-type composite containing two ferroelectric components is put forward. In this composite, ferroelectric single crystal (SC) rods and ferroelectric ceramic rods are distributed in a polymer matrix. For a lead-free 1–1–3 composite based on domain-engineered [Li_x(K${}_{1-y}$Na_y)${}_{1-x}$](Nb${}_{1-z}$Ta_z)O₃:Mn SC, effective piezoelectric coefficients $d_{3j}^{\ast }$ and $g_{3j}^{\ast }$ and energy-harvesting figures of merit (FOMs) $d_{3j}^{\ast }{g}_{3j}^{\ast }$ are studied taking an active influence of the ferroelectric components into account. In a new m–$m_c$ diagram, regions of volume fractions of SC (m) and ceramic ($m_c$) are determined where FOM $d_{33}^{\ast }{g}_{33}^{\ast }$ changes from $6\cdot 10^{-11}$ to $9\cdot 10^{-11}$ Pa${}^{-1}$. Effective parameters of the 1–1–3 and related 1–0–3 composites are compared, and consistency is shown. The large longitudinal piezoelectric coefficient $g_{33}^{\ast }$ and FOM $d_{33}^{\ast }{g}_{33}^{\ast }$ of the lead-free 1–1–3 composite are to be of interest in piezoelectric sensorics and energy harvesting.

By X-ray diffraction and dielectric spectroscopy, the crystal structure, phase composition, and properties of Sr${}_{0.6}$Ba${}_{0.4}$Nb₂O₆/Ba₂NdFeNb₄O${}_{15}$/Sr${}_{0.6}$Ba${}_{0.4}$Nb₂O₆/Ba₂NdFeNb₄O${}_{15}$/SrRuO₃/MgO and Ba₂NdFeNb₄O${}_{15}$/Sr${}_{0.6}$Ba${}_{0.4}$Nb₂O₆/Ba₂NdFeNb₄O${}_{15}$/Sr${}_{0.6}$Ba${}_{0.4}$Nb₂O₆/SrRuO₃/MgO multilayer heterostructures were studied. The heterostructures were manufactured under identical conditions but differing in the layer deposition sequence. It is shown that the orientation domains are formed in each Ba₂NdFeNb₄O${}_{15}$ (BNFN) and Sr${}_{0.6}$Ba${}_{0.4}$Nb₂O₆ (SBN) layers. BNFN and SBN layers have tetragonal unit cells with tensile out-of-plane strain and compression in-plane strain. At $T=-100\dots 100^{\circ }$C both heterostructures are characterized by fairly high relative permittivity values. The reasons for the revealed regularities are discussed.

Due to their remarkable mechanical, thermal and electrical characteristics, silicon carbide (SiC) single-walled nanotubes (SWNTs) are an unusual and promising class of materials. Density functional theory (DFT) is used in this study to examine the electrical and structural characteristics of copper-doped SiC armchair SWNTs. It has been discovered that copper doping of SiC armchair SWNTs alters the materials’ electrical characteristics. SiC SWNTs band gap plays a significant role in influencing the electrical conductivity and optical characteristics of the substance. The energy bands i.e., valence band and conduction band of SiC armchair SWNTs overlapped as copper doping concentration increased, altering the materials’ electrical conductivity and optical characteristics. Additionally, a continuous density of states plot and a narrower band gap are frequently employed as markers of ferroelectric behaviour which indicates the existence of a polarizable and highly delocalized electronic system. The significance of copper doping in SiC SWNTs is understood by this study, along with the effects of the doping on the material’s electrical properties.

The tubulin dimers of microtubules are arranged in a crystalline lattice which is wrapped to form a long cylinder. Two different arrangements of monomers within the lattice have been postulated: the A-lattice and the B-lattice. Previous studies have assumed that both lattice types are hexagonal with each dimer surrounded by six nearest-neighbors. Based on recent biochemical studies I argue that both lattice types can also be formed with each dimer having four nearest-neighbors. This has important consequences for the overall behavior of the model. It is generally assumed that tubulin dimers possess a mobile electric dipole which can exist in one of two discrete Ising spin states: -1 (down) or +1 (up). The average of all these states within a microtubule is the mean polarization and is a measure of the dipole ordering within the lattice. Microtubule models with six nearest-neighbors behave like models of ferroelectric substances: at low temperatures the lattice is highly ordered with most (if not all) dipoles pointing in the same direction, but as the temperature increases, the degree of ordering decreases due to random thermal flipping of the dipoles. The mean polarization is particularly erratic at physiological temperatures. In contrast, when the microtubule lattice is modeled with four nearest-neighbors, the mean lattice polarization is quite stable and remains close to zero over a wide temperature range that includes 37°C (310K). This raises new questions about the biophysical role of microtubules.

Materials with batch formula Pb_(1-x-3y/2)R_yBa_xNb₂O₆, where R=Y, (1-x)=0.73, 0.63, 0.53 and y=0.00, 0.02 have been prepared by the double sintering method. Substitution of yttrium (Y) restored tetragonal symmetry of PBN but reduced lattice parameters, cell volume and enhanced the density. Transition temperature of PBN has decreased due to the substitution of Y³⁺. Enhanced room temperature spontaneous polarization (P_s)=149.97 μC/sq. cm has been observed in PBN53, which is above MPB, whereas enhanced value of P_s=112.74 μC/sq. cm is found in Y: PBN63 at MPB region. The room temperature Pyroelectric coefficient (P_RT=1.07) has been observed in the composition where maximum volume of P_s is obtained. Similarly, enhanced values of piezoelectric coefficients K_p=0.244, K_t=0.353, K₃₁=0.131, d₃₁=60, d₃₃=159 and g₃₁=3.65 have also been found in the same material PBN53. Substitution of Yttrium enhanced the stiffness constant 13.59 in PBN 73 to 14.27 of Y: PBN73.

Barium strontium titanate (BST) was produced in a teflon lined pressure vessel using a high temperature hydrothermal technique and controlling the processing parameters of Ba+Sr concentration, Ba and Sr ratio, temperature, reaction period and TiO₂ concentration. It was found that this technique produces BST powders of less than 200 nm particle size with high degree of crystallinity. However, most BST powders tend to be strontium rich. Thus, excess barium in the initial solution was essential in order to produce a high barium content in the final product, which was important to obtain good electrical properties. A high TiO₂ concentration was also crucial in producing BST with a high Ba content, though this parameter was responsible for a multiphase structure. The period of hydrothermal reaction was important for stoichiometric reaction.

Ferroelectric, hysteresis, impedance spectroscopy parameters, AC conductivity, and piezoelectric properties in the ceramics of Pb_0.74K_0.52Nb₂O₆ and Pb_0.74K_0.13Sm_0.13Nb₂O₆ have been studied. X-ray diffraction study reveals single phase with the orthorhombic structure. The samples were characterized for ferroelectric and impedance spectroscopy properties from room temperature to 600°C. Cole–Cole plots (Z″ versus Z′) are drawn at different temperatures. The results obtained are analyzed to understand the conductivity mechanism in both the samples. The piezoelectric constant d₃₃ has been found to be 96 × 10^-12 C/N in PKN.

The basic cytoskeletal transport in cells is achieved by two oppositely directed processive motor proteins, kinesin and dynein, walking along microtubules. Here, we offer a new view of the mechanism of the transport direction regulation by the intrinsic cell's electric fields that interact with kinks elicited in microtubules.

Pr-doped Pb(Zr_0.65Ti_0.35)O₃ (Pb_1-xPr_x(Zr_0.65Ti_0.35)_1-x/4O₃, PPZT) ceramic samples are prepared using conventional solid-state sintering method, and their structural, dielectric, ferroelectric, and piezoelectric properties are investigated, focusing on the effects of Pr-doping. Upon increasing Pr doping level x, a transition of the crystallographic structure from rhombohedral symmetry to tetrahedral and finally to pseudocubic symmetry is observed at x ~ 0.08. The detailed dielectric measurements present a clear indication of relaxor-like behaviors at x = 0.08, while the samples at x < 0.08 offer slightly improved ferroelectric properties compared with pure Pb( Zr_0.65Ti_0.35)O₃. In spite of the dielectric relaxor behaviors induced by Pr-doping, both the ferroelectric and piezoelectric properties of PPZT are degraded at x = 0.08. The physics underlying the Pr-doping induced relaxor behaviors is then discussed.

Ceramic samples of [(Na_1-xK_x)_1/2Bi_1/2 TiO₃] (NKBT) (x = 0.1, 0.15, 0.2, 0.3, 0.45) were prepared by double sintering method. The admittance measurements were carried out in the frequency range of 1 KHz to 10 MHz in the temperature range of 30°C–600°C. The dielectric nature as deduced from admittance data shows a strong temperature and frequency dependence, apart from the relaxor behavior. The admittance data was analyzed by complex plane diagrams i.e., Y′ versus Y′′ at different temperature. The frequency explicit plots of imaginary component of electric modulus (M′′) at various temperatures show peaks shifting to higher frequencies with temperature (> 400°C). The relaxation peaks were effected by the doping. The activation energies are obtained from the data. The electromechanical coefficients K_P, K₃₁ were calculated from the resonant and anti-resonant frequencies obtained from vector admittance plots. The temperature dependence of electromechanical coefficients is studied. The solid solution samples show higher K_P, K₃₁ values as compared to pure sodium bismuth titanate.

Metal-ferroelectric-insulator-semiconductor structure capacitors with a polyvinylidene fluoride trifluoroethylene (75/25) (PVDF-TrFE) ferroelectric and a lanthanum zirconium oxide (LaZrO_x) insulator layers were fabricated on a p-type Si(100) substrate in this work. The thin films were prepared using the spin-coating method. The LaZrO_x thin films were crystallized at 750°C for 30 min in an O₂ ambient. Negligible hysteresis was observed from the C–V (capacitance-voltage) characteristic of the LaZrO_x/Si structure. The equivalent oxide thickness (EOT) was about 8.2 nm. Then the PVDF-TrFE film was spin-coated on the LaZrO_x/Si structure. To crystallize the PVDF-TrFE, the structure was annealed at 165°C for 30 min. The memory window width in the C–V curve of the Au/PVDF-TrFE/LaZrO_x/Si structure was about 4 V for a voltage sweep of ±5 V, and the leakage current density was about 10^-8A/cm² at 35 kV/cm for a 100-nm-thick film.

Perovskite structured ferroelectric (Na_1/2 Bi_1/2)_0.945Ba_0.055TiO₃ (BNBT-5.5) material has been synthesized by the conventional sintering technique. X-ray analysis on the material showed a single phase compound with rhombohedral structure with lattice parameters a = 3.89 Åand α = 89.893 Å. Frequency and temperature dependence of dielectric permittivity, impedance, modulus and conductivity have been performed in the frequency and temperature range 45 Hz–5 MHz and 35–595^°C, respectively. The observed low frequency dielectric dispersion (LFDD) in the material could be explained by Jonschers power law and evaluated activation energies at different temperature regions. Impedance spectroscopy study showed the presence of both bulk and grain boundary effects in the materials. The ac conductivity spectrum obeyed the Jonscher's power law. Modulus analysis indicated the possibility of hopping mechanism for electrical process in the system.

Au/n-Si metal-semiconductor (MS) and Au/Bi₄Ti₃O₁₂/n-Si metal-ferroelectric-semiconductor (MFS) structures were fabricated and admittance measurements were held between 5 kHz and 1 MHz at room temperature so that dielectric properties of these structures could be investigated. The ferroelectric interfacial layer Bi₄Ti₃O₁₂ decreased the polarization voltage by providing permanent dipoles at metal/semiconductor interface. Depending on different mechanisms, dispersion behavior was observed in dielectric constant, dielectric loss and loss tangent versus bias voltage plots of both MS and MFS structures. The real and imaginary parts of complex modulus of MFS structure take smaller values than those of MS structure, because permanent dipoles in ferroelectric layer cause a large spontaneous polarization mechanism. While the dispersion in AC conductivity versus frequency plots of MS structure was observed at high frequencies, for MFS structure it was observed at lower frequencies.

Crystal structure of ${\mathrm{\text{BaTiO}}}_3$ compound was studied using Atomistix Tool Kit software program at high pressure. It is defined that in this combination, tetragonal–cubic phase transition occurs under high pressure $P\approx 2$ GPa. The character of this phase transition is explained in respect of baric dependence of spontaneous strain. Birch–Murnaghan equation is solved, compression ratio is determined. Results gained by theoretical calculations are compared with experimental values.

Impedance spectroscopic studies on polycrystalline sintered discs of lanthanum doped Na_1/2(La_xBi_1-x)_1/2TiO₃ ceramics with x = 0, 0.1, 0.15 and 0.2, have been carried out in the temperature region ranging from room temperature to 550°C and in the frequency range of 100 Hz to 1 MHz. Impedance data is presented in frequency explicit plots and Cole–Cole plots. The relaxation behavior of the charge entities in the above samples is studied as a function of temperature. The structural phase transitions present in the samples showed interesting changes with composition frequency and temperature. An attempt is made to correlate the results obtained to the phase transitions present in the samples.

We report the comparison of structural, dielectric, ferroelectric and piezoelectric properties of lanthanum-modified lead zirconate titanate (PLZT) ceramics with the substitution of 7 and 8 mol% La³⁺ content in PZT (65/35) by three different formulations. The three formulations are (i) cation compensated at A-site, (ii) valency compensated at A-site and (iii) all sites (A and B) compensated. Samples were prepared by solid-state reaction route. X-ray diffraction (XRD) study shows single-phase formation with rhombohedral structure in all the samples. Scanning electron microscopy (SEM) study shows variation in grain size with different formulations. Dielectric studies for all the PLZT samples have been carried out as a function of temperature (room temperature to 350°C) at few selected frequencies (0.1, 1, 10 and 100 kHz) showing characteristics of diffuse phase transition (DPT). Dielectric properties of the poled and unpoled samples at room temperature have also been compared. All these compositions show well-defined ferroelectric behavior with significant change in the coercive field (Ec). Maximum piezoelectric properties have been obtained for the PLZT system with 8 mol% La³⁺ prepared by formulation (i).

In the present paper, we report the effect of Samarium substitution and Niobium doping on the properties of a PZT(52:48). The properties studied are: structural, dielectric and ferroelectric. The samples with chemical formula Pb_0.99Sm_0.01Zr_0.52Ti_0.48O₃ were prepared by solid-state dry ceramic method. Small amount (0.5 wt%) of Nb₂O₅ was also added. X-ray diffraction (XRD) analysis showed formation of a single phase with tetragonal structure. Dielectric properties were studied as a function of temperature and frequency. Transition temperature, T_c, was determined from dielectric constant versus temperature plot. The material shows well-defined ferroelectric (PE) hysteresis loop.