Properties Of Ferroelectric Materials Research Articles

Ferroelectric Domain Intrinsic Radiation Resistance of Lithium Niobate Ferroelectric Single−Crystal Film

The study of the properties of ferroelectric materials against irradiation has a long history. However, anti−irradiation research on the ferroelectric domain has not been carried out. In this paper, the irradiation of switched domain structure is innovatively proposed. The switched domain of 700 nm lithium niobate (LiNbO3, LN) thin film remains stable after gamma irradiation from 1 krad to 10 Mrad, which was prepared by piezoresponse force microscopy (PFM). In addition, the changing law of domain wall resistivity is explored through different sample voltages, and it is verified that the irradiated domain wall conductivity is still larger than the domain. This domain wall current (DWC) property can be applied to storage, logic, sensing, and other devices. Based on these, a ferroelectric domain irradiation resistance model is established, which explains the reason at an atomic level. The results open a possibility for exploiting ferroelectric materials as the foundation in the application of space and nuclear fields.

Ferro-Electric RAM

Ferroelectric RAM (FRAM) is a promising non-volatile memory technology that combines the advantages of both DRAM and Flash memory. FRAM offers fast read and write speeds, low power consumption, and high endurance, making it suitable for a wide range of applications. It stores data by utilizing the ferroelectric properties of certain materials, which can retain their polarization even when the power is off. This allows FRAM to offer high-speed operation with low power consumption, making it ideal for use in IoT devices, smart cards, and automotive systems

Tuning structural, dielectric, and ferroelectric properties of BTO-based ceramics through dual-site substitution

Different strategies for tuning the properties of ferroelectric materials have been employed for advancing electromechanical applications. Among several material synthesis techniques explored, site substitution is an effective approach. The present work focuses on Ba1-xCaxSnyTi1-yO3 (BCST) ceramics prepared by solid-state sintering route with different substitution levels (x = 0, 0.05 and y = 0, 0.09). The impact of site substitution on the properties of Barium Titanate (BTO), phase purity, structural analysis, chemical composition, dielectric, and ferroelectric properties have been studied. An ionic radii difference at A-site and B-site substitution is a key factor to achieve significant changes in physical and structural properties. X-ray diffraction patterns ensure the formation of pure phase perovskite structure in all the compositions. Raman spectroscopy indicates Ca substitution not only occurs at the A-site but also within the oxygen octahedra, adversely affecting the properties. Ca and Sn act as strong grain growth inhibitors, leading to a fine-grained and dense microstructure in BCST. While Ca substitution has a limited impact on the Curie temperature (TC), Sn substitution lowers TC in BST (54 °C) and BCST (50 °C) compared to BTO (126 °C). The Sn substitution results in the coexistence of multiple phases (rhombohedral, tetragonal and orthorhombic) in BST, enhancing its properties (ε' = 6118 at RT, Pr = 5.50 μC/cm2, Q11 = 0.060 m4/C2, d*33 = 526 pm/V) in comparison to BTO. These results acknowledge the role of substituents in lattice disruption, paving the way for chemistry-based materials design in the field of dielectric, actuator and energy storage applications.

Predicting Dielectric Properties of Ferroelectric Materials with Point Defects by a Phase-Field Model

Predicting Dielectric Properties of Ferroelectric Materials with Point Defects by a Phase-Field Model

Strain tuning on Van der Waals negative capacitance transistors

Negative differential capacitance induced by the energy barrier formed by the nonlinear ferroelectric insulating layer during the phase transition in negative capacitance field effect transistors (NCFETs) can break through the fundamental thermionic limit of the metal-oxide-semiconductor field effect transistors (MOSFETs), which is set at a subthreshold swing (SS) of 60 mV/dec at room temperature for low-power switching. Strain engineering has been shown effective for modulating both intrinsic and coupled properties of ferroelectric materials. However, while the modulation of negative capacitance (NC) by strain primarily remains within theoretical predictions, there is a lack of experimental studies to explore its effect on NCFETs. This study introduces strain to NCFETs by utilizing the magnetostriction of Terfenol-D upon the applied magnetic field. Results reveal a decrease in SSmin from 43.5 mV/dec to 15.2 mV/dec with a compressive strain increase from 0 to −0.005%. Additionally, theoretical results by using time-evolving Ginzburg-Landau equations and Kirchhoff's laws demonstrate that compressive strain enhances both the amplitude and duration of transient NC in CuInP2S6, while vice versa under tensile strain. This work offers valuable insights for the design of NCFET devices.

Relaxor ferroelectricity and elevated thermal expansion behaviour of (1−x)Bi0.5Na0.5TiO3-xBaSnO3 lead-free piezoelectric ceramics

The study on piezoelectric and ferroelectric properties of sodium bismuth titanate-based materials is essential for piezoelectric electronic components. In this study, a series of lead-free relaxor ferroelectric (1−x)Bi0.5Na0.5TiO3-xBaSnO3 (BNT-xBS) ceramics were prepared by a conventional solid-state reaction method. The phase performance, fracture morphologies, permittivity, ferroelectricity, piezoelectricity, and thermal expansion for various BS contents (x) were systematically studied. With an increase in x, the phase transition from R3c to P4bm, and the grain size marginally decreased from 1.79 to 1.51 μm. Meanwhile, the degree of dielectric relaxor and diffused phase transition improved, and the ferroelectricity and piezoelectricity initially increased and then decreased. The optimal electrical properties of Pr = 41.6 μC/cm2, d33 = 167.8 pC/N, and kp = 0.318 were observed at x = 0.06. The paper discusses how site disorder, long-range electric dipole ordering, and grain size influence various electrical properties. The mechanism of the thermal expansion behaviour was investigated based on Born-Lande theory. This study could serve as a landmark for studying multifunctional BNT-based piezoelectric materials for potential energy-harvesting devices.

Designs where disorder prevails.

A design strategy boosts electrical properties of ferroelectric materials and devices.

Mathematical analysis of the dynamics of solitary wave solutions to the time-fractional thin-film ferroelectric materials model

The thin-film ferroelectric materials equation is a fundamental mathematical model to explain the behavior of polarized electric fields in ferroelectric materials possessing unique properties such as piezoelectricity, pyroelectricity, electrostriction, hysteresis, spontaneous polarization, etc. These significant properties of ferroelectric materials are important in the progress of capacitors, non-volatile memories, electrical sensors, as well as optical and biomedical devices, among other applications. The aim of the present study is to explore applicable soliton solutions to the fractional-order model to the aforementioned equation by addressing the improved F-expansion method. Through analysis and rigorous identification, various radical solutions, including trigonometric, hyperbolic, and rational forms of the model, are established, and significant solitons are restored by setting appropriate parameter values in the analytical solutions obtained, which are demonstrated through 3D, 2D, and contour plots. We also explore the impact of fractional derivative as well as the parameters, like pressure, temperature, and others included in the model to determine the polarization effect in ferroelectric materials. This study uncovers several novel solutions along with their states in response to external or internal field parameters, which might be helpful in understanding the nature of ferroelectric materials.

Enhancing ferroelectric performance in hafnia-based MFIS capacitor through interface passivation and bulk doping

In recent times, there has been a notable surge of interests in hafnia (HfO2)-based ferroelectrics, primarily due to their remarkable ferroelectric properties employed in ultra-thin configurations, alongside their compatibility with the conventional CMOS manufacturing process. In order to harness the full potential of HfO2-based films for high-performance non-volatile memory applications, it is imperative to enhance their ferroelectric characteristics and durability. This study introduces a straightforward approach aimed at augmenting the ferroelectric performance of Hf x Zr1−x O2 (HZO) films deposited on silicon (Si) substrates through the engineering of oxygen vacancies (V O). The results of this endeavor demonstrate a significant enhancement in ferroelectric performance, characterized by a 2Pr value of 47 μC cm−2 and impressive endurance, enduring up to 108 cycles under an 8 MV cm−1 electric field without the need of a wake-up process. This marked improvement can be attributed to a dual-pronged approach, involving the incorporation of an Al2O3 interlayer and the introduction of Al atoms into the HZO film. The Al2O3 interlayer primarily serves to mitigate the presence of oxygen vacancies at the interface, while the introduction of Al dopants elevates the concentration of oxygen vacancies within the bulk material. This modulation of oxygen vacancy concentration proves instrumental in facilitating the formation of a ferroelectric o-III phase within the HZO-based films, thereby further augmenting their ferroelectric performance. This innovative and effective strategy offers an alternative avenue for enhancing the ferroelectric properties of materials characterized by a fluorite crystal structure.

Effect of temperature on dislocation-tuned dielectricity and piezoelectricity in single-crystal BaTiO3

The pinning-controlled mobility of ferroelectric/ferroelastic domain walls is an important part of managing polarization switching and determining the final properties of ferroelectric and piezoelectric materials. Here, we assess the impact of temperature on dislocation-induced domain wall pinning as well as on dislocation-tuned dielectric and piezoelectric response in barium titanate single crystals. Our solid-state nuclear magnetic resonance spectroscopy results indicate that the entire sample exclusively permits in-plane domains, with their distribution remaining insensitive to temperature changes below the Curie temperature (TC). The domain wall pinning field monotonically decreases with increasing temperature up to TC, as evidenced by a combination of experimental observations and phase-field simulations. Our work highlights the promising potential of dislocation engineering in controlling domain wall mobility within bulk ferroelectrics.

Two-dimensional Janus AgBiP2X3X[formula omitted] (X, X[formula omitted] = S, Se, Te): Efficient intrinsic electric field regulatory strategy for photocatalytic overall water-splitting

Exploring highly efficient catalysts that utilize visible light for water-splitting shows immense potential in addressing energy and environmental challenges. However, most photocatalysts are faced with challenges such as low carrier migration ability, high carrier recombination rate, and insufficient driving force for water-splitting reactions. Here, based on the two-dimensional (2D) AgBiP2X6 (X = S, Se, Te) structures, we construct Janus AgBiP2X3X3′ (X, X′ = S, Se, Te) monolayers and theoretically investigate their photocatalytic performance. The results indicate that the Janus method effectively regulate the energy band structure and intrinsic electric field (EF) of the materials. The Janus AgBiP2S3Te3 structure possesses an optimal band gap and band edge position in comparison to AgBiP2X6. Among all the investigated materials, AgBiP2S3Te3 possesses the largest intrinsic EF. The vertical intrinsic EF in Janus AgBiP2S3Te3 facilitates spatial separation of photogenerated electrons and holes, allowing hydrogen evolution reaction (HER) to take place on its top surface and oxygen evolution reaction (OER) to occur on its bottom surface, thereby effectively preventing carrier recombination. The limiting potentials for OER and HER reactions are significantly reduced. The OER can proceeds spontaneously under neutral conditions. The Gibbs free energy change (ΔG) of the HER is 0.075 eV under acidic conditions at pH = 0, which closely approaches the optimal value of 0. Simultaneously, the Janus AgBiP2S3Te3 exhibits kinetic and thermal stability, suitable appfavorableropriate electron and hole mobility, and excellent visible light absorption capability. Our work not only predict a series of new 2D materials, but also paves a strategy for improving the photocatalytic properties of 2D ferroelectric materials.

Research progress on photocatalytic reduction of CO2 based on ferroelectric materials.

Transforming CO2 into renewable fuels or valuable carbon compounds could be a practical means to tackle the issues of global warming and energy crisis. Photocatalytic CO2 reduction is more energy-efficient and environmentally friendly, and offers a broader range of potential applications than other CO2 conversion techniques. Ferroelectric materials, which belong to a class of materials with switchable polarization, are attractive candidates as catalysts due to their distinctive and substantial impact on surface physical and chemical characteristics. This review provides a concise overview of the fundamental principles underlying photocatalysis and the mechanism involved in CO2 reduction. Additionally, the composition and properties of ferroelectric materials are introduced. This review expands on the research progress in using ferroelectric materials for photocatalytic reduction of CO2 from three perspectives: directly as a catalyst, by modification, and construction of heterojunctions. Finally, the future potential of ferroelectric materials for photocatalytic CO2 reduction is presented. This review may be a valuable guide for creating reasonable and more effective photocatalysts based on ferroelectric materials.

Ultrafast and accurate prediction of polycrystalline hafnium oxide phase-field ferroelectric hysteresis using graph neural networks.

Polycrystalline hafnium oxide emerges as a promising material for the future of nanoelectronic devices. While phase-field modeling stands as a primary choice tool for forecasting domain structure evolution and electromechanical properties of ferroelectric materials, it suffers from a high computational cost, which impedes its applicability to real-size systems. Here, we propose a Graph Neural Network (GNN) machine-learning framework to predict the ferroelectric hysteresis of polycrystalline hafnium oxide, with the goal of significantly accelerating computations in contrast to high-fidelity phase-field methods. By leveraging the inherent graph structure of the polycrystalline system and incorporating edge-level feature properties through graph attentional layers, our approach accurately predicts hysteresis behaviors across a broad range of polycrystalline structures, grain numbers, and Landau coefficients. The GNN framework exhibits high accuracy, with an average relative error of ∼4%, and demonstrates remarkable computational efficiency with respect to ground truth phase-field simulations, offering speed-ups exceeding a million-fold. Furthermore, we showcase the transferability of our model to efficiently scale predictions in polycrystals comprising up to a thousand grains, paving the way for effective simulations of real-sized systems. Our approach, by overcoming computational limitations in polycrystalline hafnium oxide, opens doors for accelerating discovery and design in ferroelectric materials.

The unique spontaneous polarization property and application of ferroelectric materials in photocatalysis

The unique spontaneous polarization property and application of ferroelectric materials in photocatalysis

Asymmetric fracture behavior in ferroelectric materials induced by flexoelectric effect

Ferroelectric materials are widely used in actuators, exciters, and memory devices due to their excellent electromechanical properties. However, the instinctive brittleness of ferroelectric materials makes them easy to fracture under external load. Since giant strain gradient can be easily generated near the crack tip, the flexoelectric effect is indispensable in the research of fracture properties of ferroelectric materials. With the combination of time-dependent Ginzburg–Landau theory and phase-field model, the electromechanical behavior of PbTiO3 in the vicinity of the crack tip is determined in this work. The simulation results demonstrate that the domain structure near the crack tip becomes asymmetric with the flexoelectric effect. The polarization switching-induced toughening, which is characterized by the J-integral, depends on the direction of the crack relative to the original polarization orientation. Furthermore, the longitude flexoelectric coefficient f11 has more significant impact on the fracture toughness than that of the transverse flexoelectric coefficient f12 and the shear flexoelectric coefficient f44. The results of the present work suggest that the flexoelectric effect must be considered in the reliable design of ferroelectric devices.

Obtaining and Characterizing the Dielectric and Ferroelectric Properties of the PZT-Pms Complex System Through Solid State Reactions and Spark Plasma Sintering

Abstract In this paper B-oxide sintering process and Spark plasma Sintering (SPS) method is used to synthesize 0.88Pb(Zr0.52Ti0.48)O3 – 0.12Pb(Mn1/3Sb2/3)O3 – x at%Pr complex system where x = 0 and 0.02. The sintering temperature used in the SPS technique is considerably lower than that used in the B-oxide method (200 to 400oC) with significant decrease of the duration of the sintering route, arriving to some minutes instead of some hours. The aim of the study is the investigation of the effect of sintering technique on the dielectric and ferroelectric properties of such piezoelectric materials. The properties of the developed ceramic materials were determined: the development of crystalline phases was investigated by X-ray diffraction technique and the microstructural behavior by scanning electron microscopy was observed. The composition obtained by the SPS technique shows a lower remnant polarization and maximum strain, as well as a higher coercive field, compared to the those obtained using the same composition produced by B-oxide method.

Polar topological superdomain arrays in PMN-PT crystals engineered via a voltage-free method

Domain engineering is an active field of research that aims to enhance the functional properties of ferroelectric materials for various applications. This work presents a voltage-free method for fabricating topological superdomain arrays in 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-28PT) crystals. During the cooling process from high-temperature paraelectric phase to room temperature ferroelectric phase, the out-of-plane polarization of PMN-28PT crystals in contact with aluminum can be fully regulated downward, attributed to the difference in the work function of aluminum and PMN-28PT. In conjunction further with photolithography and ultraviolet light illumination, it is easy to obtain periodic strip domain structures with alternating up and down polarization. Moreover, this method can also control in-plane polarization, resulting in a large-scale central divergent/convergent topological superdomain array. These findings provide insights into ferroelectric domain engineering and have implications for the development of electromechanical, piezoelectronic, and photonic devices.

Flexoelectric and electrostatic effects on mechanical properties of CuInP2S6

Ferroelectric polarization is crucial to the development of modern electronic devices. The mechanical properties of ferroelectric materials are however interlinked with its polarization through piezoelectricity and flexoelectricity, as uniform and non-uniform mechanical deformation can bring about changes of polarization. While the mechanical properties of ferroelectric domains and domain walls of conventional ferroelectric oxides have been investigated widely, the mechanical properties of two-dimensional ferroelectrics (van der Waals ferroelectrics) have barely been studied, although they have drawn significant attention due to the need for miniaturization in new-generation low-energy nanoelectronics. Here, we report on variations in mechanical properties of copper indium thiophosphate (CuInP2S6, CIPS), which shows mechanical softening at 180° domain walls, and we discuss flexoelectric and electrostatic effects on the elastic modulus of its ferroelectric domains. In addition, an inhomogeneous mechanical response in mixed-phase CuInP2S6-In4/3P2S6 heterostructures has also been observed. The ferroelectric CuInP2S6 phase appears to be stiffer than the non-polar In4/3P2S6 phase, while the phase boundaries between the two phases, interestingly, display the lowest elastic modulus. Our findings provide new insight into the mechanical properties of two-dimensional ferroelectrics, which may inspire further investigation and applications of these materials.

Two-Dimensional Ferroelectric C2N/In2Se3 Heterobilayer with Tunable Electronic Property and Photovoltaic Effect.

Two-dimensional ferroelectric monolayer materials with reversible spontaneous polarization provide more regulatory dimensions for their relevant van der Waals heterostructures. Using first-principles calculations, we construct the C2N/In2Se3 bilayer heterostructure and study its physical properties as well as the effects of E-field and strain. The results indicate that the intrinsic polarization of the component In2Se3 monoalyer can significantly adjust the electronic properties of the C2N/In2Se3 heterobilayer. When the polarization of the In2Se3 monolayer points to the interface (up-In2Se3), the C2N/In2Se3 bilayer behaves as the type-I indirect band gap heterostructure, while it transforms to the type-II direct band gap heterostructure after reversing the polarization of the In2Se3 monolayer (dp-In2Se3). Furthermore, the two C2N/In2Se3 heterostructures both have enhanced optical absorption in the visible region than the isolated In2Se3 and C2N monolayers. More importantly, the external electric field and strain can easily regulate the electronic properties of the C2N/In2Se3 heterostructures. The power conversion efficiency (PCE) of the type-II C2N/dp-In2Se3 heterostructure is 8.16%, and the electric field of 0.1 V/Å and the strain of -2% can transform the C2N/up-In2Se3 heterostructure into type-II one, conducive to the high PCE up to 24.03 and 24%, respectively. Our proposed C2N/In2Se3 heterostructure is promising in future luminescent and photovoltaic fields, and our findings also provide a strategy for functionalizing 2D monolayer materials by the intrinsic polarization property of ferroelectric materials.

The unexpected diffuse phase transition in relaxor-PbTiO3 ferroelectrics via acceptor modification

The diffuse phase transition (DPT) and domain structure are essential to the functional properties of relaxor ferroelectrics and are extremely sensitive to the ion doping. The utilization of acceptor doping has been observed to be an effective method in enhancing the high-power properties of relaxor ferroelectric materials. The present study aims to examine the acceptor-doped DPT and domain structure in single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3. An unexpected physical phenomenon was identified in which Mn-doping increased dielectric diffusion and lowered domain size while suppressing dielectric relaxation. Traceability investigations suggest that Mn-doping inhibited the growth of polar nanoregions by enhancing random electric fields, which increases dielectric diffusion while decreasing the domain size. Meanwhile, Mn doping redistributes the relaxation time function, which results in a reduction in dielectric relaxation. The current research deepens the understanding of the physical basis of DPT and can be applied to the development of high-performance piezoelectric materials.