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First part: Schematic illustration of ferroelectric, piezoelectric, and pyroelectric effects in ferroelectrics. Second part: Mapping of piezoelectric coefficient (d33) and Tc relative to some important time frame. Third part: Conventional application of ferroelectrics in dielectrics. Fourth part: Emerging application potential (i.e., energy harvesting and environmental protection).
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In the past century, ferroelectrics are well known in electroceramics and microelectronics for their unique ferroelectric, piezoelectric, pyroelectric, and photovoltaic effects. Nowadays, the advances in understanding and tuning of these properties have greatly promoted a broader application potential especially in energy and environmental fields,...
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The discovery of ferroelectric hafnium oxide revived the research on ferroelectric integrated devices in microelectronics for memory, radio frequency as well as piezoelectric or pyroelectric applications.
In this habilitation thesis we want to cover a broad scope on the research which was undertaken towards application of integrated ferroelectric...
Citations
... On the other hand, sufficient active reaction sites on the surface and large specific areas are also crucial in deciding the catalytic behavior. 13,14 However, the active photogenerated charges can easily recombine, impairing the energy conversion efficiency. ...
The fast recombination of photogenerated electrons and holes remains a major issue in hindering photocatalytic efficiency. Apart from traditional methods, such as rare metal deposition and element doping, the introduction of a built‐in electric field has been proven an efficient way in recent years. Ferroelectrics, which possess spontaneous polarization and associated polarization electric fields, are attracting more attention as photocatalysts. In this study, Bi2MoO6 spheres with different hierarchical upper nanostructures are synthesized through a one‐pot hydrothermal method. With this porous structure and the intrinsic ferroelectricity, BMO spheres present excellent physisorption and photodegradation ability toward dye molecules. After corona poling treatment, the ferroelectric field of the BMO samples was enhanced, and the recombination of charges was suppressed, leading to an obvious increase in photocatalytic rate. The origin BMO‐5 can reach a total degradation of RhB in 20 min, and the polarized BMO‐5 (BMO‐5P) can remove all RhB molecules instantly through the physisorption process. Apart from BMO‐5, other samples also present excellent catalytic behavior. Origin BMO‐2 can fully degrade the RhB in 40 min, and the degradation time of polarized BMO‐2P is 30 min. The hierarchical structure and internal polarized electric field endow BMO spheres with outstanding adsorption purification and photodegradation ability and provide a new comprehensive strategy for the catalyst design.
... Currently, heterostructure construction [16], defect engineering [17], and chemical modification [18] have been used to enhance the catalytic efficacy of piezoelectric materials. It is well known that the design of morphotropic phase boundaries (MPBs) greatly improved the electrical properties of piezoelectric materials [19]. The coexistence of multiple phases provides more directions for polarization, which facilitates polarization rotation. ...
An internal built electric field can suppress the recombination of electron–hole pairs and distinctly enhance the catalytic activity of a photocatalyst. Novel t-Ag/0.95AgNbO3-0.05LiTaO3 heterojunction was prepared by reducing silver nanoparticles (Ag NPs) on the surface of the piezoelectric powder 0.95AgNbO3-0.05LiTaO3 (0.05-ANLT) using a simple mechanical milling method. The effects of milling time and excitation source used for the degradation of organic dye by heterojunction catalysts were investigated. The results demonstrate that the optimized 1.5-Ag/0.05-ANLT heterojunction removes 97% RhB within 40 min, which is 7.8 times higher than that of single piezoelectric catalysis and 25.4 times higher than that of single photocatalysis. The significant enhancement of photocatalytic activity can be attributed to the synergistic coupling of the surface plasmon resonance (SPR) effect and the piezoelectric effect.
... Recently, researchers have reported progress in overcoming the limitations between structure and performance by introducing point defects into ferroelectrics. Their findings indicate that defects can considerably alter material properties, increase piezoelectricity, and enhance piezoelectric catalytic activity [52]. This demonstrates that defects play a crucial role in catalytic systems, not only governing the energy band structure but also serving as charge trapping centers to decrease the electron and hole complexation rate, thereby significantly enhancing the catalytic activity. ...
... By the end of the 21st century, the excessive amount of CO 2 in the atmosphere (the main component of greenhouse gases) is likely to increase global temperature by 2. 3-5.4 ℃ [4], causing climate change and negatively impacting ecological balance. Moreover, the rapid depletion of nonrenewable fossil fuels will eventually lead to a worldwide energy crisis [5]. Hence, it is imperative to explore green energy sources and discover effective and efficient ways to converting CO 2 into high-value fuels and chemicals [6]. ...
Electrocatalytic carbon dioxide reduction (CO2RR) is a promising strategy to achieve carbon neutrality. Nevertheless, its practical viability is hindered by the energy-consuming anodic oxygen evolution (OER) process. In recent years, researchers have attempted to break this limitation by some novel anodic OER substitution reactions to improve the overall economic profitability. This article aims to provide a comprehensive review covering the recent development of integrated CO2RR systems with alternative OER oxidation reactions. Starting from the presentation of fundamental considerations of electrolytic configurations, energy efficiency, value-added products and tech-economic analysis for high-performance integrations, the recent innovative anodic reactions are then summarized and thoroughly analyzed including the reactions involving alcohols, biomass, chlorine, water contaminants oxidations and chemicals electrosynthesis, with the focus on electrocatalysts design, electrolyte selection and system configurations. Finally, the current challenges and future perspectives are discussed to achieve the dual goals of sustainability and profitability in an economical and energy-efficient way.
... Since both defects and epitaxial strain can affect the ferroelectricity, we also analyzed the effect of epitaxial strain on the phonon band structures. Fig. 4a, b show that there is no obvious variation in the distribution of the flat polar phonon band Defect-dipolar states in fluorite MO 2 (M = Hf and Zr) Point defects can induce local distortion due to mismatched size relative to host ions 18,29,[53][54][55] . In conventional perovskite metal oxides, point-defect induced defect-dipoles and their correlation with intrinsic polarization are general due to the symmetryconforming property of point defects 56 . ...
The scale-free ferroelectric polarization of fluorite M O 2 ( M = Hf, Zr) due to flat polar phonon bands are promising for nonvolatile memories. Defects are also widely introduced to improve the emergent ferroelectricity. However, their roles are still not fully understood at the atomic-level. Here, we report a significant effect of point-defect-driven flattening of polar phonon bands with more polar modes and polarization contribution in doped M O 2 . The polar phonon bands in La-doped M O 2 ( M = Hf, Zr) can be significantly flattened, compared with pure ones. However, the lower energy barrier with larger polarization of V O -only doped M O 2 compared with La-doped cases suggest that V O and local lattice distortion should be balanced for high-performance fluorite ferroelectricity. The work is believed to bridge the relation between point defects and the generally enhanced induced ferroelectricity in fluorite ferroelectrics at the atomic-level and inspire their further property optimization via defect-engineering.
... It is worth noting that there are two sets of spatially separated surface charge in the FE QL Al 2 S 3 : One is the intrinsic polarization charge and the other is the induced (free) charge. In addition, the induced (free) charge, electron and hole, always accompanies the polarization (positive and negative) charge in FE materials [69,70]. The number of polarization charge is positively correlated with the total electrostatic potential difference ( φ) in 2D ferroelectric materials [56,71]. ...
For two-dimensional (2D) polarized monolayers or type-II heterostructure semiconductors, the semiconductor-to-metal transition (SMT) process usually occurs under doping engineering or external electric field. In this work, we point out that the evolution of band offset, surface charge redistribution, and inner-layer charge transfer are synergetic in polarized monolayer semiconductors. Taking quintuple-layer (QL) Al 2 S 3 as an example, the SMT process occurs by substituting the surface S atom with the O atom and applying external electric field by two methods. Our results reveal that the SMT derives from the increased surface charge on two-surface atoms. The SMT mechanism in polarized QL-Al 2 S 3 is also applicable to other 2D polarized monolayers and heterostructure semiconductors.
... To date, various approaches (doping, 4,5 defect engineering, 6,7 etc., for ceramic materials and ceramic filler inclusion, 8−10 electrospinning, 11,12 etc., for polymer materials) have been utilized to amplify the output properties of PEH. On the other hand, for TEH, output power density, which is a measure of its superiority, mainly depends on the dielectric constant and surface charge density of the triboelectric layers. ...
Here, in this present work, the development of a lightweight,
flexible hybrid energy harvester using a composite BaTi0.89Sn0.11O3 (BTS)/
polydimethylsiloxane (PDMS) has been proposed. A significantly enhanced
output performance of hybrid energy harvester (HEH) was achieved by
strategically coupling the piezoelectric effect with the triboelectric output.
Thus, multiphase coexisted BTS particles as confirmed by the structural and
dielectric properties, with a high value of d33 coefficient ∼412 pC/N, were
used as filler for the functional layer (PDMS) of the device. The hybrid
energy harvesting device can harvest a maximum voltage of ∼358 V with an
instantaneous power density of 1.08 mW/cm2 from human finger imparting
(force ∼ 100 N, frequency ∼ 4 Hz). The fabricated device harvests energy
from handwriting and differentiates fine patterns of different letters by using
it as a writing pad. In addition to that, a wireless system utilizing an
inductor-based resonant coupling mechanism was developed for wireless
power transmission. The easy processability, flexibility, high output performance, and alignment toward a power source for wireless
power transmission make the fabricated HEH device a promising candidate for various applications for portable smart flexi-electronics
... Recently, with the continuous growth of the world population and the acceleration of industrialization, energy consumption has increased significantly, which has led to a high demand for energy storage equipment to compensate for the interruption of renewable energy [1,2]. Considering the limited resources and environmental issues, it is very important to develop lead-free energy storage materials [3]. ...
Sr0.7Bi0.2TiO3-based ceramics with excellent dielectric temperature stability and energy storage efficiency (η) are expected to be applied in dielectric ceramic capacitors. Unfortunately, low breakdown strength (BDS) limits its application. In this work, the new Sr0.7Bi0.2TiO3@xNaNb0.9Ta0.1O3 (x = 5–20 mol%, SBT@xNNT) relaxor ferroelectric ceramics with fine grains were prepared by a two-step sintering process. The introduction of NNT causes the coexistence of multiphase in ceramics, which enhances the relaxation behavior and the temperature stability of energy storage. Meanwhile, the design of core–shell structure also improves the temperature stability of the ceramics. Thus, the energy density (Wrec) of 2.2 J/cm³ and η of 76% are achieved in Sr0.7Bi0.2TiO3@xNaNb0.9Ta0.1O3 ceramics at 249 kV/cm, and Wrec exhibits good temperature stability from 20 to 150 °C. The Sr0.7Bi0.2TiO3@xNaNb0.9Ta0.1O3 ceramics have excellent dielectric temperature stability (|Δε/ε20 °C|≤ 15%) at − 60–120 °C. The as-prepared SBT@10NNT ceramics are suitable for the application in dielectric ceramic capacitors. This study provides SBT-based ceramics for a novel strategy for optimizing the energy storage performance.
... Perovskite ferroelectric materials, including single crystals, ceramics and thin films, are widely used in piezoelectric sensors, actuators and transducers, pyroelectric photodetectors, electrooptic switches, dielectric energy storage devices and other electronic devices [1][2][3][4][5][6][7]. As an important lead-free ferroelectric system, (1-x%)(Na 0.5 Bi 0.5 )TiO 3 -x% BaTiO 3 (NBT-xBT) has been widely studied due to giant electrostrains [8][9][10]. ...
Relaxor ferroelectrics (1-x%)(Na0.5Bi0.5)TiO3-x%BaTiO3 (NBT-xBT) have been widely studied in recent years for the high electrostrains and special structural features. However, there are some structure evolutions still unclear, such as the transition occurring at the temperature of dielectric frequency dispersion vanishes. Here, in-situ polarized Raman scattering was utilized to investigate the evolutions of the lattice structure induced by temperature and electric field. The Raman-active modes for P4bm NBT-8BT were separated and identified under the framework of group theory. By observing A1 modes, it is found that electric field cannot induce ferroelectric state after the frequency dispersion vanishes, demonstrating a competition between relaxor characteristics and long-range ferroelectric order which evolves with temperature. According to B2 modes, the P4bm-P4mm transition was not observed under extra-high electric fields. This work interpretates the Raman scattering and lattice evolutions of NBT-8BT, and proposes a method to analyze Raman spectrum which is generally applicable to other ferroelectrics.
... Since the first mention of the pyrocatalytic concept for water remediation in 2012, it has been extensively studied with the goal of establishing it as an effective advanced oxidation process (AOP) [1][2][3][4]. The unique feature of pyrocatalysis is the possibility to harvest thermal energy from the environment or waste heat from industrial plants [5]. ...
Among the numerous techniques for water remediation, disinfection, and hydrogen generation, only pyrocatalysis has the potential to harvest and utilize energy from the environment as well as industrial processes in the form of temperature differences. In this work, our purpose was to reach a drastic improvement of the pyrocatalytic activity of BaTiO3 powders (BT) by decreasing the particle size in combination with catalyst annealing at temperatures between RT and 1000 °C. In the end, we reached our goal for a BT with a nominal particle diameter of 50 nm via low-temperature annealing at temperatures of only 300 °C. The activity boost was demonstrated for the dichlorofluorescein (DCF) oxidation assay (+585%), the degradation of 4-hexylresorcinol (+1150%) and, for the first time, the successful degradation of the micropollutant bisphenol A (+460%). Using material characterization in combination with in-depth literature comparisons, we elucidated the underlying mechanism. It deviates strongly from our original assumptions as it includes the generation of oxygen vacancies. Based on our findings, several strategies for further improving pyrocatalysis were derived to enable an effective catalyst design. This will help pyrocatalysis to take the next step on its way towards an energy-efficient technique for water remediation.
