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Ultra-low hysteresis electric field-induced strain with high electrostrictive coefficient in lead-free Ba(Zr Ti1-)O3 ferroelectrics
摘要： From the application point of view, high electric field-induced strain with ultra-low hysteresis or hysteresis-free characteristic is highly desired in high-precision displacement actuators. In this work, lead-free Ba(ZrxTi1-x)O3 (BZT) ferroelectrics with x in the range between 0.02 and 0.1 were fabricated by a conventional solid state reaction method. The structural evolution and electrical properties were investigated systematically with an emphasis on electrostrictive effect. As x increases from 0.02 to 0.1, the crystal lattice parameters (a and c axes) increase while the tetragonality (c/a-1) goes down. In addition, the Curie temperature (TC) of BZT decreases gradually, while the temperatures corresponding to tetragonal-to-orthorhombic (T-O) and orthorhombic-to-rhombohedral (O-R) phase transitions increase. Ultra-low hysteresis (<8%) and high electric field-induced strains (>0.15% at 60 kV/cm) are observed in all studied compositions. Most importantly, a high longitudinal electrostrictive coefficient Q33 (0.0453 m4/C2) was also identified in x=0.1 composition. This work not only reports high electric field-induced strains with ultra-low hysteresis and high Q33 in lead-free BZT ferroelectrics, but also indicates a potential application for BZT ceramics in high-precision displacement actuators.
关键词： Electrostriction,Ferroelectric,Lead-free,Electric field induced strain,BZT
更新于2025-09-23 15:22:29
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Fabrication, electrical and magnetic properties of 0.7(BiGd <sub/>x</sub> Fe <sub/>1?x</sub> O <sub/>3</sub> )?0.3(PbTiO <sub/>3</sub> ) composites
摘要： The polycrystalline samples having chemical formula 0.7(BiGdxFe1?xO3)?0.3(PbTiO3) (x = 0.0, 0.05, 0.10, 0.15 and 0.20) were fabricated by using high temperature mixed oxide route. The X-ray diffraction spectra suggested rhombohedral (major) symmetry with small impurity phases. The surface microstructure showed a highly dense packing of grains throughout the wider area for all samples. The dielectric permittivity and loss factor of all samples were studied with the help of temperature-dependent dielectric parameters. The relaxation mechanism was suggested from the dielectric and impedance spectroscopy. The conduction mechanism of all samples was investigated. The P–E and M–H loops of all the samples were taken at room temperature showing the multiferroic properties.
关键词： Dielectric,conductivity,magnetic properties,ferroelectric,impedance
更新于2025-09-23 15:22:29
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A non-isothermal phase-field model for piezo–ferroelectric materials
摘要： We propose a model for the study of piezo–ferroelectric materials, based on the Ginzburg–Landau approach to the ferroelectric transition, in which the inelastic deformation is a direct function of the ferroelectric polarization. The non-isothermal effects related to the phase change and other dissipative phenomena are considered by a suitable energy balance equation, according to the restrictions of the second principle. The hysteresis phenomena for polarization and inelastic strain are considered from both the energetic perspective of the vector Ginzburg–Landau equation and the dissipation-dominated perspective of the rate-independent evolutionary equations.
关键词： Ferroelectric,Phase field,Ferroelastic,Non-isothermal model,Hysteresis
更新于2025-09-23 15:22:29
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Polar metals as electrodes to suppress the critical-thickness limit in ferroelectric nanocapacitors
摘要： Enhancing the performance of nanoscale ferroelectric (FE) field-effect transistors and FE capacitors for memory devices and logic relies on miniaturizing the metal electrode/ferroelectric area and reducing the thickness of the insulator. Although size reductions improve data retention, deliver lower voltage threshold switching, and increase areal density, they also degrade the functional electric polarization. There is a critical nanometer length t(cid:1) FE below which the polarization disappears owing to depolarizing field effects. Here, we show how to overcome the critical thickness limit imposed on ferroelectricity by utilizing electrodes formed from a novel class of materials known as polar metals. Electronic structure calculations on symmetric polar-metal electrode/FE capacitor structures demonstrate that electric polarizations persist to the sub-nanometer scale with t(cid:1) ! 0 FE when a component of the polar axis in the electrode is perpendicular to the electrode/insulator interface, i.e., aligned along the direction of the polar displacements in the ferroelectric. Our results reveal the importance of interfacial dipolar coherency in sustaining the polarization, which provides a platform for in reduced dimensions. Published by AIP Publishing. https://doi.org/10.1063/1.5049607
关键词： polar metals,depolarizing field,critical thickness,ferroelectric,nanocapacitors
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) PHYSICS, TECHNOLOGIES AND INNOVATION (PTI-2018): Proceedings of the V International Young Researchers’ Conference - Ekaterinburg, Russia (14–18 May 2018)] - Synthesis and investigation of functional layers for composite multiferroics
摘要： This article is devoted to the synthesis and investigation of thin ferroelectric and magnetostrictive layers as potential constituents of composite multiferroics. We chose alloy Fe10Ni90 as magnetostrictive medium. The magnetic anisotropy and magnetoelastic properties of films Fe10Ni90 are investigated. It is shown that they can be significantly modified with a variation in the thickness of the samples in the range 40-80 nm. We chose polyvinylidene fluoride(PVDF) as ferroelectric medium. Its films were obtained by spin-coating and had a thickness of ~200 nm. The analysis of the crystallinity and phase composition of the films are completed. It is established that the factors influencing on these properties are the thickness of the films and the conditions for their heat treatment. The magnetic properties of the PVDF / Fe10Ni90 film structures with optimized parameters of layered components are determinate.
关键词： magnetostrictive,PVDF,ferroelectric,composite multiferroics,Fe10Ni90
更新于2025-09-23 15:21:21
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A thermodynamic potential for barium zirconate titanate solid solutions
摘要： Barium zirconate titanate [Ba(ZrxTi1?x)O3] solid solutions are promising lead-free ferroelectric materials that have received substantial interest. Thermodynamic analysis based on phenomenological Landau–Devonshire theory is a powerful method for theoretical investigation of ferroelectric materials, but cannot be applied to Ba(ZrxTi1?x)O3 because there is no thermodynamic potential. In this paper, a thermodynamic potential for Ba(ZrxTi1?x)O3 (0 ≤ x ≤ 0.3) solid solutions is constructed, and then a thermodynamic analysis carried out. The results accurately reproduce known phase structures and their transition temperatures, with good agreement with experimentally measured polarization, dielectric, and piezoelectric constants. It is found that Ba(ZrxTi1?x)O3 solid solutions at room temperature have three phase boundaries, including a tetragonal–orthorhombic phase boundary at x = 0.013, an orthorhombic–rhombohedral phase boundary at x = 0.0798, and a rhombohedral–paraelectric phase boundary at x = 0.2135. The results also indicate that the chemical composition-induced ferroelectric–paraelectric phase boundary has superior electromechanical properties, suggesting a new way to enhance electromechanical coupling in Ba(ZrxTi1?x)O3 solid solutions.
关键词： Landau–Devonshire theory,electromechanical properties,solid solutions,lead-free ferroelectric materials,Barium zirconate titanate,phase boundaries,thermodynamic potential
更新于2025-09-23 15:21:21
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Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets || Modified Spin Coating Method for Coating and Fabricating Ferroelectric Thin Films as Sensors and Solar Cells
摘要： Spin coating process with a modified spin coater is performed well, especially the second generation of modified spin coater, which has a maximum value of 18,000 rpm, is able for manufacturing/coating photonic crystal‐based ferroelectric thin films that require a high angular velocity (rpm). Ferroelectric thin films that use both 3000 and 6000 rpm have given good results in energy gap, electrical conductivity, etc. In addition, the modified spin coater has also produced several applications such as sensors in the device of blood sugar level noninvasively, sensors in the automatic drying system, sensors in the robotic system, and photovoltaic cells in the system of solar cells/panels which are being developed at present. These applications used ferroelectric material such as barium strontium titanate (BST), lithium niobate (LiNbO3), cuprous oxide (CuO), and lithium tantalate (LiTaO3).
关键词： ferroelectric thin films,solar cells,modified spin coating,sensors
更新于2025-09-23 15:21:21
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Highly Sensitive Room-Temperature Sensor Based on Nanostructured K2W7O22 for Application in the Non-Invasive Diagnosis of Diabetes
摘要： Diabetes is one of the most rapidly-growing chronic diseases in the world. Acetone, a volatile organic compound in exhaled breath, shows a positive correlation with blood glucose and has proven to be a biomarker for type-1 diabetes. Measuring the level of acetone in exhaled breath can provide a non-invasive, low risk of infection, low cost, and convenient way to monitor the health condition of diabetics. There has been continuous demand for the improvement of this non-invasive, sensitive sensor system to provide a fast and real-time electronic readout of blood glucose levels. A novel nanostructured K2W7O22 has been recently used to test acetone with concentration from 0 parts-per-million (ppm) to 50 ppm at room temperature. The results revealed that a K2W7O22 sensor shows a sensitive response to acetone, but the detection limit is not ideal due to the limitations of the detection system of the device. In this paper, we report a K2W7O22 sensor with an improved sensitivity and detection limit by using an optimized circuit to minimize the electronic noise and increase the signal to noise ratio for the purpose of weak signal detection while the concentration of acetone is very low.
关键词： non-invasive,biomarker,ferroelectric property,blood glucose,volatile organic compound,acetone,nanostructured K2W7O22,diabetes
更新于2025-09-23 15:21:21
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A Robust Artificial Synapse Based on Organic Ferroelectric Polymer
摘要： Memristors with history-dependent resistance are considered as artificial synapses and have potential in mimicking the massive parallelism and low-power operation existing in the human brain. However, the state-of-the-art memristors still suffer from excessive write noise, abrupt resistance variation, inherent stochasticity, poor endurance behavior, and costly energy consumption, which impedes massive neural architecture. A robust and low-energy consumption organic three-terminal memristor based on ferroelectric polymer gate insulator is demonstrated here. The conductance of this memristor can be precisely manipulated to vary between more than 1000 intermediate states with the highest OFF/ON ratio of ≈104. The quasicontinuous resistive switching in the MoS2 channel results from the ferroelectric domain dynamics as confirmed unambiguously by the in situ real-time correlation between dynamic resistive switching and polarization change. Typical synaptic plasticity such as long-term potentiation and depression (LTP/D) and spike-timing dependent plasticity (STDP) are successfully simulated. In addition, the device is expected to experience 1 × 109 synaptic spikes with an ultralow energy consumption for each synaptic operation (less than 1 fJ, compatible with a bio-synaptic event), which highlights its immense potential for the massive neural architecture in bioinspired networks.
关键词： artificial synapses,organic,PVDF,ferroelectric,memristors
更新于2025-09-23 15:21:21
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Ferroelectric random access memory with high electric properties and high production yield realized by employing an AlO <sub/>x</sub> underlying layer of Pt bottom electrode for a La-doped lead zirconate titanate capacitor
摘要： Although ferroelectric random access memory (FRAM) has superior electric properties, its downside is that it has a relatively larger cell area in comparison other non-volatile memories. We tried to apply TiOx, and AlOx to an underlying layer (TiOx-UL, AlOx-UL) instead of our previously used Ti underlying layer (Ti-UL) for the La-doped lead zirconate titanate (PLZT) capacitor to obtain a high polarization value aiming to a lowering cell area. The failed bit ratio of the FRAM with TiOx-UL was found to be higher than that with AlOx-UL even though polarization values of the PLZT capacitor with both underlying layers are almost the same and much higher than that with Ti-UL. It is strongly suggested that the imprint induced in PLZT by charged defect is a main cause of bit failure by fail-bit analysis. X-ray diffraction and atomic force microscopy observations shows that charged defect density in PLZT over TiOx-UL is possibly higher than that in PLZT over AlOx-UL due to surface roughness of underlying layers.
关键词： FRAM,AlOx underlying layer,Ferroelectric random access memory,production yield,polarization,PLZT capacitor,TiOx underlying layer
更新于2025-09-23 15:21:21