This review presents the progress and current status of the investigation on electromechanical deformation and fracture of piezo electric/ferroelectric materials. An attempt is made to summarize a few fundamental aspe...This review presents the progress and current status of the investigation on electromechanical deformation and fracture of piezo electric/ferroelectric materials. An attempt is made to summarize a few fundamental aspects, which include electromechanical constitutive relations, piezoelectric micromechanics and electric fracture and fatigue, instead of describing all technological backgrounds, basic physics, experimental findings, and theoretical developments. A number of open questions and future prospective are presented. It is hoped that this review will encourage people to join the exploration of this important and interesting field.展开更多
Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state refrigeration.The discovery of giant ECE in ferroelectric thin f...Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state refrigeration.The discovery of giant ECE in ferroelectric thin films has greatly renewed the research activities and significantly stimulated experimental and theoretical investigations.In this review,the recent progress on the theoretical modeling of ECE in ferroelectric and antiferroelectric materials are introduced,which mainly focuses on the phase field modeling and first-principles based effective Hamiltonian method.We firstly provide the theoretical foundation and technique details for each method.Then a comprehensive review on the progress in the application of two methods and the strategies to tune the ECE are presented.Finally,we outline the practical procedure on the development of multi-scale computational method without experiemtal parameters for the screening of optimized electrocaloric materials.展开更多
Barium strontium titanate/magnesia （BSTO/MgO） ferroelectric material for phase shift was prepared by traditional solid phase synthesis. The phase distribution, microstructure and electric properties were investigate...Barium strontium titanate/magnesia （BSTO/MgO） ferroelectric material for phase shift was prepared by traditional solid phase synthesis. The phase distribution, microstructure and electric properties were investigated. The results show that no secondary phase appears in the composites and the dimension of grains distributes uniformly. With 50 wt% MgO content, the dielectric tunability reaches 17.5 % in the external DC field of 4 000 Vomm^-1 and the microwave loss at about 2.5 GHz is 8×10^-3. Hence, it can be applied in tunable microwave phase shifters.展开更多
In this big data era, the explosive growth of information puts ultra-high demands on the data storage/computing, such as high computing power, low energy consumption, and excellent stability. However, facing this chal...In this big data era, the explosive growth of information puts ultra-high demands on the data storage/computing, such as high computing power, low energy consumption, and excellent stability. However, facing this challenge, the traditional von Neumann architecture-based computing system is out of its depth owing to the separated memory and data processing unit architecture. One of the most effective ways to solve this challenge is building brain inspired computing system with in-memory computing and parallel processing ability based on neuromorphic devices. Therefore, there is a research trend toward the memristors, that can be applied to build neuromorphic computing systems due to their large switching ratio, high storage density, low power consumption, and high stability. Two-dimensional (2D) ferroelectric materials, as novel types of functional materials, show great potential in the preparations of memristors because of the atomic scale thickness, high carrier mobility, mechanical flexibility, and thermal stability. 2D ferroelectric materials can realize resistive switching (RS) because of the presence of natural dipoles whose direction can be flipped with the change of the applied electric field thus producing different polarizations, therefore, making them powerful candidates for future data storage and computing. In this review article, we introduce the physical mechanisms, characterizations, and synthetic methods of 2D ferroelectric materials, and then summarize the applications of 2D ferroelectric materials in memristors for memory and synaptic devices. At last, we deliberate the advantages and future challenges of 2D ferroelectric materials in the application of memristors devices.展开更多
Energy harvesting is an appealing technology that makes use of the ambient energy which is otherwise wasted. Piezoelectric materials directly convert the elastic energy to the electric energy, and thus have a great ad...Energy harvesting is an appealing technology that makes use of the ambient energy which is otherwise wasted. Piezoelectric materials directly convert the elastic energy to the electric energy, and thus have a great advantage in scavenging vibrational energy for simplicity in device structure with relatively high power density. This paper provides an overview on the research of piezoelectric materials in energy harvesting in recent decades, from basics of piezoelectricity and working principle of energy harvesting with piezoelectric materials, to the progress of development of high-performance piezoelectrics including ceramics, single crystals and polymers, then to experimental attempts on the device fabrication and optimization, finally to perspective applications of piezoelectric energy harvesting(PEH). The criteria for selection of materials for PEH applications are introduced. Not only the figure of merit but also maximum allowable stress of materials are taken into account in the evaluation of their potential in achieving high energy density and output power density. The influence of the device configuration on the performance is also acknowledged and discussed. The magnitude and distribution of induced stress in the piezoelectric unit upon excitation by the vibration source play an important role in determining the output power density and can be tuned via proper design of device configuration without changing its resonant frequency. Approaches to address the issue of frequency match accompanying with the resonant mode are illustrated with literature examples. Usage of PEH devices can be extended to a variety of vibration sources in everyday life as well as in nature. Some appealing applications of PEH, such as in implantable and wearable devices, are reviewed.展开更多
At present,the research on ferroelectric photovoltaic materials mainly focuses on photoelectric detection.In the context of the rapid development of the Internet of Things(IoT),it is particularly important to use smal...At present,the research on ferroelectric photovoltaic materials mainly focuses on photoelectric detection.In the context of the rapid development of the Internet of Things(IoT),it is particularly important to use smaller thin-film devices as sensors.In this work,an indium tin oxide/bismuth ferrite(BFO)/lanthanum nickelate device has been fabricated on an F-doped tin oxide glass substrate using the sol–gel method.The sensor can continuously output photoelectric signals with little environmental impact.Compared to other types of sensors,this photoelectric sensor has an ultra-low response time of 1.25 ms and ultra-high sensitivity.Furthermore,a material recognition system based on a BFO sensor is developed.It can effectively identify eight kinds of materials that are difficult for human eyes to distinguish.This provides new ideas and methods for developing the IoT in material identification.展开更多
In recent years,the emergence of numerous applications of artificial intelligence(AI)has sparked a new technological revolution.These applications include facial recognition,autonomous driving,intelligent robotics,and...In recent years,the emergence of numerous applications of artificial intelligence(AI)has sparked a new technological revolution.These applications include facial recognition,autonomous driving,intelligent robotics,and image restoration.However,the data processing and storage procedures in the conventional von Neumann architecture are discrete,which leads to the“memory wall”problem.As a result,such architecture is incompatible with AI requirements for efficient and sustainable processing.Exploring new computing architectures and material bases is therefore imperative.Inspired by neurobiological systems,in-memory and in-sensor computing techniques provide a new means of overcoming the limitations inherent in the von Neumann architecture.The basis of neural morphological computation is a crossbar array of high-density,high-efficiency non-volatile memory devices.Among the numerous candidate memory devices,ferroelectric memory devices with non-volatile polarization states,low power consumption and strong endurance are expected to be ideal candidates for neuromorphic computing.Further research on the complementary metal-oxide-semiconductor(CMOS)compatibility for these devices is underway and has yielded favorable results.Herein,we first introduce the development of ferroelectric materials as well as their mechanisms of polarization reversal and detail the applications of ferroelectric synaptic devices in artificial neural networks.Subsequently,we introduce the latest developments in ferroelectrics-based in-memory and in-sensor computing.Finally,we review recent works on hafnium-based ferroelectric memory devices with CMOS process compatibility and give a perspective for future developments.展开更多
Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this wor...Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.展开更多
Differential capacitance is derived based upon energy,charge or current considerations,and determined when it may go negative or positive.These alternative views of differential capacitances are analyzed,and the relat...Differential capacitance is derived based upon energy,charge or current considerations,and determined when it may go negative or positive.These alternative views of differential capacitances are analyzed,and the relationships between them are shown.Because of recent interest in obtaining negative capacitance for reducing the subthreshold voltage swing in field effect type of devices,using ferroelectric materials characterized by permittivity,these concepts are now of paramount interest to the research community.For completeness,differential capacitance is related to the static capacitance,and conditions when the differential capacitance may go negative in relation to the static capacitance are shown.展开更多
The development of stable and efficient visible light-absorbing oxide-based semiconductor photocatalysts is a desirable task for solar water splitting applications.Recently,we proposed that the low photocurrent densit...The development of stable and efficient visible light-absorbing oxide-based semiconductor photocatalysts is a desirable task for solar water splitting applications.Recently,we proposed that the low photocurrent density in film-based BiFeO_(3)(BFO)is due to charge recombination at the interface of the domain walls,which could be largely reduced in particulate photocatalyst systems.To demonstrate this hypothesis,in this work we synthesized particulate BFO and Mn-doped BiFeO_(3)(Mn-BFO)by the sol-gel method.Photocatalytic water oxidation tests showed that pure BFO had an intrinsic photocatalytic oxygen evolution reaction(OER)activity of 70μmol h^(-1) g^(-1),while BFO-2,with an optimum amount of Mn doping(0.05%),showed an OER activity of 255μmol h^(-1) g^(-1) under visible light(λ≥420 nm)irradiation.The bandgap of Mn-doped BFO could be reduced from 2.1 to 1.36 eV by varying the amount of Mn doping.Density functional theory(DFT)calculations suggested that surface Fe(rather than Mn)species serve as the active sites for water oxidation,because the overpotential for water oxidation on Fe species after Mn doping is 0.51 V,which is the lowest value measured for the different Fe and Mn species examined in this study.The improved photocatalytic water oxidation activity of Mn-BFO is ascribed to the synergistic effect of the bandgap narrowing,which increases the absorption of visible light,reduces the activation energy of water oxidation,and inhibits the recombination of photogenerated charges.This work demonstrates that Mn doping is an effective strategy to enhance the intrinsic photocatalytic water oxidation activity of particulate ferroelectric BFO photocatalysts.展开更多
Microbial fuel cells(MFCs)are bio-electrochemical systems that can directly convert the chemical energy contained in an effluent into bioelectricity by the action of microorganisms.The performance of these devices is ...Microbial fuel cells(MFCs)are bio-electrochemical systems that can directly convert the chemical energy contained in an effluent into bioelectricity by the action of microorganisms.The performance of these devices is heavily impacted by the choice of the material that forms the cathode.This work focuses on the assessment of ferroelectric and photocatalytic materials as a new class of non-precious catalysts for MFC cathode construction.A series of cathodes based on mixed oxide solid solution of LiTaO_3with WO_3formulated as Li_(1-x)Ta_(1-x)W_xO_3(x=0,0.10,0.20 and0.25),were prepared and investigated in MFCs.The catalyst phases were synthesized,identified and characterized by DRX,PSD,MET and UV–Vis absorption spectroscopy.The cathodes were tested as photoelectrocatalysts in the presence and in the absence of visible light in devices fed with industrial wastewater.The results revealed that the catalytic activity of the cathodes strongly depends on the ratio of substitution of W^(6+)in the LiTaO_3matrix.The maximum power densities generated by the MFC working with this series of cathodes increased from60.45 mW·m^(-3)for x=0.00(LiTaO_3)to 107.2 mW·m^(-3)for x=0.10,showing that insertion of W^(6+)in the tantalate matrix can improve the photocatalytic activity of this material.Moreover,MFCs operating under optimal conditions were capable of reducing the load of chemical oxygen demand by 79%(COD_(initial)=1030 mg·L^(-1)).展开更多
Since the appearance of Rochelle salt,ferroelectrics have received extensive attention from researchers due to they are playing an important role in sensors,memories,mechanical actuation,and so on.In recent years,with...Since the appearance of Rochelle salt,ferroelectrics have received extensive attention from researchers due to they are playing an important role in sensors,memories,mechanical actuation,and so on.In recent years,with the rapid development of molecular ferroelectrics,high-performance molecular ferroelectrics have become effective complement to inorganic ferroelectrics.However,compared with inorganic ferroelectrics,the family of molecular ferroelectrics is relatively scarce,and exploring highperformance ferroelectric materials through new synthesis strategies has become the trend of molecular ferroelectrics.Here,we successfully transformed non-polar material 1(2-H_(2)PCA)_(2)(H_(2)O)CdCl_(6)(2-H_(2)PCA=2-picolylamine cation)into polar material 2(2-H_(2)PCA)2CdCl_(6)by single-crystal to single-crystal transformation(SCSCT).Meanwhile,2 exhibits clear ferroelectricity with a high-temperature Tc of 378 K,a Ps of 1.18μC/cm^(2)at 300 K.This work not only realizes the purpose of synthesizing ferroelectrics by forming polar structures by SCSCT,but also realizes the reversibility of SCSCT,which provides ideas for the construction and exploration of new molecular ferroelectrics.展开更多
BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfacto...BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.展开更多
Perovskite BaTiO3 （BTO） nanocrystals with a size of 150-200 nm have successfully been synthesized via a facile hydrothermal method by employing titanate nanowires as synthetic precursor. Tetragonality and spontaneou...Perovskite BaTiO3 （BTO） nanocrystals with a size of 150-200 nm have successfully been synthesized via a facile hydrothermal method by employing titanate nanowires as synthetic precursor. Tetragonality and spontaneous ferroelectric polarization of BTO nanocrystals have been determined by X-ray diffraction and transmission electron microscopy investigations. BTO nanocrystals loaded with Pt nanoparticles in a size of 2-5 nm have been explored as a catalyst towards CO oxidation to CO2. It is interesting to find that CO catalytic conversion rate over Pt-BTO nanocrystals gradually decreased and further increased near 100 ℃ when the catalytic temperature keeps increasing, whereas the conversion behavior in oxides is expected to be enhanced upon the catalytic temperature grows. Using differential scanning calorimetry and first-principle calculations, the observed catalytic behavior has been discussed on the basis of the ferroelectric polarization effect and the ferroelectric-paraelectric transition of BTO nanocrystals with a Curie temperature of 110 ℃. Below Curie temperature, CO catalytic oxidation could be significantly tailored by ferroelectric polarization of BTO nanocrystals via a promoted dissociation of O2 molecules. The findings suggest that a ferroelectric polarization in perovskite oxides could be an alternative way to modify the CO catalytic oxidation.展开更多
Hybrid organic-inorganic perovskites （e.g. CH;NH;PbI;） have attracted tremendous attention due to their promise for achieving next-generation cost-effective and high performance optoelectronic devices.These hybrid o...Hybrid organic-inorganic perovskites （e.g. CH;NH;PbI;） have attracted tremendous attention due to their promise for achieving next-generation cost-effective and high performance optoelectronic devices.These hybrid organic-inorganic perovskites possess excellent optical and electronic properties, including strong light absorption, high carrier abilities, optimized charge diffusion lengths, and reduced charge recombination etc., leading to their widespread applications in advanced solar energy technologies （e.g.high efficiency perovskite solar cells）. However, there is still a lack of investigations regarding fundamental properties such as ferroelectricity in these perovskites.As conventional ferroelectric ceramics are prepared at high temperature and have no mechanically flexibility,low-temperature proceed and flexible perovskite ferroelectrics have become promising candidates and should be exploited for future flexible ferroelectric applications. Here, ferroelectric properties in hybrid organic-inorganic perovskites and several state-of-the-art perovskite ferroelectrics are reviewed. Novel ferroelectric applications of hybrid organic-inorganic perovskites are discussed as well, providing guideline for realizing future high performance and flexible ferroelectric devices.展开更多
Sr^2＋ modified polycrystalline PZT-PMN ceramics were synthesized by a semi-wet route. Impedance spectroscopy studies indicate the bulk and grain boundary effects of PZT-PMN material along with the negative temperatur...Sr^2＋ modified polycrystalline PZT-PMN ceramics were synthesized by a semi-wet route. Impedance spectroscopy studies indicate the bulk and grain boundary effects of PZT-PMN material along with the negative temperature coefficient of resistance. The bulk conductiv-ity exhibits an Arrhenius-type thermally activated hopping process which is supported by the AC conductivity behavior as a function of fre-quency and temperature. It is observed that the remnant polarization increases with an increase in the Sr2＋content in PZT-PMN.展开更多
The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study...The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study,we conducted a systematic study on the microstructures and ferroelectric properties of Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with various annealing rates in the rapid thermal annealing.It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size,reduced surface roughness and a higher portion of orthorhombic phase.Moreover,these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates.The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films,which was weakened with decreasing annealing rate.Our findings revealed that this internal stress,along with the stress originating from the top/bottom electrode,plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films.By carefully controlling the annealing rate,we could effectively regulate the tension stress within HZO thin films,thus achieving precise control over their ferroelectric properties.This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.展开更多
A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation in...A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation instability. The problems of mesh sensitivity and convergence, and the efficiency of the proposed nonlinear FE technique have been assessed to illustrate the versatility and potential accuracy of the said technique. The nonlinear electromechanical behavior, such as the hysteresis loops and butterfly curves, of ferroelectric ceramics subjected to both a uniform electric field and a point electric potential has been studied numerically. The results obtained are in good agreement with those of the corresponding theoretical and experimental analyses. Furthermore, the electromechanical coupling fields near （a） the boundary of a circular hole, （b） the boundary of an elliptic hole and （c） the tip of a crack, have been analyzed using the proposed nonlinear finite element method （FEM）. The proposed nonlinear electromechanically coupled FEM is useful for the analysis of domain switching, deformation and fracture of ferroelectric ceramics.展开更多
Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of...Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.展开更多
High-performance ferroelectric materials are widely used in various electronic devices owing to the function of mutual conversion among different energies,which mainly relates to their special structure gene of polari...High-performance ferroelectric materials are widely used in various electronic devices owing to the function of mutual conversion among different energies,which mainly relates to their special structure gene of polarization configuration.Recent researches show that the high-entropy strategy has emerged as an effective and flexible approach for boosting physical properties in high-entropy ferroelectrics via the delicate design of local polarization configurations and other intrinsic effects caused by entropy increment,such as entropy stabilization,lattice disorder,inhibition of grain coarsening,improved mechanical properties,cocktail effect,and so on.In this review,the recent research progress about high-entropy ferroelectrics has been summarized,especially for the directional design of novel local polarization configurations according to the characteristics of different electrical properties such as high piezoelectricity,high-efficiency energy storage,and large electrostriction,providing a guidance for designing and exploring more novel local polarization configurations in high-entropy ferroelectrics for generating higher performance.展开更多
基金The project supported by the National Natural Science Foundation of China (10025209)
文摘This review presents the progress and current status of the investigation on electromechanical deformation and fracture of piezo electric/ferroelectric materials. An attempt is made to summarize a few fundamental aspects, which include electromechanical constitutive relations, piezoelectric micromechanics and electric fracture and fatigue, instead of describing all technological backgrounds, basic physics, experimental findings, and theoretical developments. A number of open questions and future prospective are presented. It is hoped that this review will encourage people to join the exploration of this important and interesting field.
基金the financial support from the National Natural Science Foundation of China(Grant No.11972320)Zhejiang Provincial Natural Science Foundation(Grant No.LZ17A020001).
文摘Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state refrigeration.The discovery of giant ECE in ferroelectric thin films has greatly renewed the research activities and significantly stimulated experimental and theoretical investigations.In this review,the recent progress on the theoretical modeling of ECE in ferroelectric and antiferroelectric materials are introduced,which mainly focuses on the phase field modeling and first-principles based effective Hamiltonian method.We firstly provide the theoretical foundation and technique details for each method.Then a comprehensive review on the progress in the application of two methods and the strategies to tune the ECE are presented.Finally,we outline the practical procedure on the development of multi-scale computational method without experiemtal parameters for the screening of optimized electrocaloric materials.
基金Funded by the Commission of Science Technology and Industry for National Defense(No.MKPT-03-155)
文摘Barium strontium titanate/magnesia （BSTO/MgO） ferroelectric material for phase shift was prepared by traditional solid phase synthesis. The phase distribution, microstructure and electric properties were investigated. The results show that no secondary phase appears in the composites and the dimension of grains distributes uniformly. With 50 wt% MgO content, the dielectric tunability reaches 17.5 % in the external DC field of 4 000 Vomm^-1 and the microwave loss at about 2.5 GHz is 8×10^-3. Hence, it can be applied in tunable microwave phase shifters.
基金We acknowledge grants from the National Natural Science Foundation of China(Grant No.61974093)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515012479)+1 种基金the Science and Technology Innovation Commission of Shenzhen(Grant Nos.RCYX20200714114524157 and JCYJ20220818100206013)the NTUT-SZU Joint Research Program(Grant No.NTUT-SZU-112-02).
文摘In this big data era, the explosive growth of information puts ultra-high demands on the data storage/computing, such as high computing power, low energy consumption, and excellent stability. However, facing this challenge, the traditional von Neumann architecture-based computing system is out of its depth owing to the separated memory and data processing unit architecture. One of the most effective ways to solve this challenge is building brain inspired computing system with in-memory computing and parallel processing ability based on neuromorphic devices. Therefore, there is a research trend toward the memristors, that can be applied to build neuromorphic computing systems due to their large switching ratio, high storage density, low power consumption, and high stability. Two-dimensional (2D) ferroelectric materials, as novel types of functional materials, show great potential in the preparations of memristors because of the atomic scale thickness, high carrier mobility, mechanical flexibility, and thermal stability. 2D ferroelectric materials can realize resistive switching (RS) because of the presence of natural dipoles whose direction can be flipped with the change of the applied electric field thus producing different polarizations, therefore, making them powerful candidates for future data storage and computing. In this review article, we introduce the physical mechanisms, characterizations, and synthetic methods of 2D ferroelectric materials, and then summarize the applications of 2D ferroelectric materials in memristors for memory and synaptic devices. At last, we deliberate the advantages and future challenges of 2D ferroelectric materials in the application of memristors devices.
基金supported by the National Natural Science Foundation of China(Grant No.51302143)Shenzhen Special Fund for the Development of Emerging Industries(Grant No.JCYJ20140417115840233)Shenzhen Peacock Plan(Grant No.KQCX20140521161756228)
文摘Energy harvesting is an appealing technology that makes use of the ambient energy which is otherwise wasted. Piezoelectric materials directly convert the elastic energy to the electric energy, and thus have a great advantage in scavenging vibrational energy for simplicity in device structure with relatively high power density. This paper provides an overview on the research of piezoelectric materials in energy harvesting in recent decades, from basics of piezoelectricity and working principle of energy harvesting with piezoelectric materials, to the progress of development of high-performance piezoelectrics including ceramics, single crystals and polymers, then to experimental attempts on the device fabrication and optimization, finally to perspective applications of piezoelectric energy harvesting(PEH). The criteria for selection of materials for PEH applications are introduced. Not only the figure of merit but also maximum allowable stress of materials are taken into account in the evaluation of their potential in achieving high energy density and output power density. The influence of the device configuration on the performance is also acknowledged and discussed. The magnitude and distribution of induced stress in the piezoelectric unit upon excitation by the vibration source play an important role in determining the output power density and can be tuned via proper design of device configuration without changing its resonant frequency. Approaches to address the issue of frequency match accompanying with the resonant mode are illustrated with literature examples. Usage of PEH devices can be extended to a variety of vibration sources in everyday life as well as in nature. Some appealing applications of PEH, such as in implantable and wearable devices, are reviewed.
基金supported by the National Natural Science Foundation of China(Grant No.52072041)the Beijing Natural Science Foundation(Grant No.JQ21007)the University of Chinese Academy of Sciences(Grant No.Y8540XX2D2).
文摘At present,the research on ferroelectric photovoltaic materials mainly focuses on photoelectric detection.In the context of the rapid development of the Internet of Things(IoT),it is particularly important to use smaller thin-film devices as sensors.In this work,an indium tin oxide/bismuth ferrite(BFO)/lanthanum nickelate device has been fabricated on an F-doped tin oxide glass substrate using the sol–gel method.The sensor can continuously output photoelectric signals with little environmental impact.Compared to other types of sensors,this photoelectric sensor has an ultra-low response time of 1.25 ms and ultra-high sensitivity.Furthermore,a material recognition system based on a BFO sensor is developed.It can effectively identify eight kinds of materials that are difficult for human eyes to distinguish.This provides new ideas and methods for developing the IoT in material identification.
基金supported by National Key Research and Development Program of China(2021YFA1200700)The National Natural Science Foundation of China(T2222025 and 62174053)+2 种基金Open Research Projects of Zhejiang Lab(2021MD0AB03)Shanghai Science and Technology Innovation Action Plan(21JC1402000 and 21520714100)the Fundamental Research Funds for the Central Universities。
文摘In recent years,the emergence of numerous applications of artificial intelligence(AI)has sparked a new technological revolution.These applications include facial recognition,autonomous driving,intelligent robotics,and image restoration.However,the data processing and storage procedures in the conventional von Neumann architecture are discrete,which leads to the“memory wall”problem.As a result,such architecture is incompatible with AI requirements for efficient and sustainable processing.Exploring new computing architectures and material bases is therefore imperative.Inspired by neurobiological systems,in-memory and in-sensor computing techniques provide a new means of overcoming the limitations inherent in the von Neumann architecture.The basis of neural morphological computation is a crossbar array of high-density,high-efficiency non-volatile memory devices.Among the numerous candidate memory devices,ferroelectric memory devices with non-volatile polarization states,low power consumption and strong endurance are expected to be ideal candidates for neuromorphic computing.Further research on the complementary metal-oxide-semiconductor(CMOS)compatibility for these devices is underway and has yielded favorable results.Herein,we first introduce the development of ferroelectric materials as well as their mechanisms of polarization reversal and detail the applications of ferroelectric synaptic devices in artificial neural networks.Subsequently,we introduce the latest developments in ferroelectrics-based in-memory and in-sensor computing.Finally,we review recent works on hafnium-based ferroelectric memory devices with CMOS process compatibility and give a perspective for future developments.
基金financially supported by the National Key Research and Development Program of China(No.2019YFB1503500)
文摘Ferroelectric materials are widely applied in the ferroelectronic devices,photovoltaics,and so on.Ultrathin ferroelectric thin films are highly desired for their applications,which still remain a challenge.In this work,the ultrathin barium titanate(BaTiO_(3),BTO)films are deposited directly on the fluorine-doped tin oxide glass(SnO_(2):F,FTO)substrates by radio frequency magnetron sputtering method at different temperatures.All BTO ultrathin films exhibit strong ferroelectric properties.Interestingly,BTO thin films deposited at room temperature(RT)also exhibit robust ferroelectricity.The polar domains are switched reversibly with a phase degree of~180°by piezoelectric force microscopy for the BTO thin films deposited at room temperature,attributing to the strain and ion migration.
文摘Differential capacitance is derived based upon energy,charge or current considerations,and determined when it may go negative or positive.These alternative views of differential capacitances are analyzed,and the relationships between them are shown.Because of recent interest in obtaining negative capacitance for reducing the subthreshold voltage swing in field effect type of devices,using ferroelectric materials characterized by permittivity,these concepts are now of paramount interest to the research community.For completeness,differential capacitance is related to the static capacitance,and conditions when the differential capacitance may go negative in relation to the static capacitance are shown.
文摘The development of stable and efficient visible light-absorbing oxide-based semiconductor photocatalysts is a desirable task for solar water splitting applications.Recently,we proposed that the low photocurrent density in film-based BiFeO_(3)(BFO)is due to charge recombination at the interface of the domain walls,which could be largely reduced in particulate photocatalyst systems.To demonstrate this hypothesis,in this work we synthesized particulate BFO and Mn-doped BiFeO_(3)(Mn-BFO)by the sol-gel method.Photocatalytic water oxidation tests showed that pure BFO had an intrinsic photocatalytic oxygen evolution reaction(OER)activity of 70μmol h^(-1) g^(-1),while BFO-2,with an optimum amount of Mn doping(0.05%),showed an OER activity of 255μmol h^(-1) g^(-1) under visible light(λ≥420 nm)irradiation.The bandgap of Mn-doped BFO could be reduced from 2.1 to 1.36 eV by varying the amount of Mn doping.Density functional theory(DFT)calculations suggested that surface Fe(rather than Mn)species serve as the active sites for water oxidation,because the overpotential for water oxidation on Fe species after Mn doping is 0.51 V,which is the lowest value measured for the different Fe and Mn species examined in this study.The improved photocatalytic water oxidation activity of Mn-BFO is ascribed to the synergistic effect of the bandgap narrowing,which increases the absorption of visible light,reduces the activation energy of water oxidation,and inhibits the recombination of photogenerated charges.This work demonstrates that Mn doping is an effective strategy to enhance the intrinsic photocatalytic water oxidation activity of particulate ferroelectric BFO photocatalysts.
基金partially supported by the Spanish Ministry of Science and Innovation(MICINN)by the FEDER(Fondo Europeo de Desarrollo Regional),ref.CICYT ENE2011-25188by the Seneca Foundation 18975/JLI/2013 grants
文摘Microbial fuel cells(MFCs)are bio-electrochemical systems that can directly convert the chemical energy contained in an effluent into bioelectricity by the action of microorganisms.The performance of these devices is heavily impacted by the choice of the material that forms the cathode.This work focuses on the assessment of ferroelectric and photocatalytic materials as a new class of non-precious catalysts for MFC cathode construction.A series of cathodes based on mixed oxide solid solution of LiTaO_3with WO_3formulated as Li_(1-x)Ta_(1-x)W_xO_3(x=0,0.10,0.20 and0.25),were prepared and investigated in MFCs.The catalyst phases were synthesized,identified and characterized by DRX,PSD,MET and UV–Vis absorption spectroscopy.The cathodes were tested as photoelectrocatalysts in the presence and in the absence of visible light in devices fed with industrial wastewater.The results revealed that the catalytic activity of the cathodes strongly depends on the ratio of substitution of W^(6+)in the LiTaO_3matrix.The maximum power densities generated by the MFC working with this series of cathodes increased from60.45 mW·m^(-3)for x=0.00(LiTaO_3)to 107.2 mW·m^(-3)for x=0.10,showing that insertion of W^(6+)in the tantalate matrix can improve the photocatalytic activity of this material.Moreover,MFCs operating under optimal conditions were capable of reducing the load of chemical oxygen demand by 79%(COD_(initial)=1030 mg·L^(-1)).
基金supported by the National Natural Science Foundation of China(Nos.22175079,22205087 and 22275075)Natural Science Foundation of Jiangxi Province(Nos.20225BCJ23006 and 20224ACB204002)Science and Technology Project of Jiangxi Provincial Department of Education(No.GJJ210880)。
文摘Since the appearance of Rochelle salt,ferroelectrics have received extensive attention from researchers due to they are playing an important role in sensors,memories,mechanical actuation,and so on.In recent years,with the rapid development of molecular ferroelectrics,high-performance molecular ferroelectrics have become effective complement to inorganic ferroelectrics.However,compared with inorganic ferroelectrics,the family of molecular ferroelectrics is relatively scarce,and exploring highperformance ferroelectric materials through new synthesis strategies has become the trend of molecular ferroelectrics.Here,we successfully transformed non-polar material 1(2-H_(2)PCA)_(2)(H_(2)O)CdCl_(6)(2-H_(2)PCA=2-picolylamine cation)into polar material 2(2-H_(2)PCA)2CdCl_(6)by single-crystal to single-crystal transformation(SCSCT).Meanwhile,2 exhibits clear ferroelectricity with a high-temperature Tc of 378 K,a Ps of 1.18μC/cm^(2)at 300 K.This work not only realizes the purpose of synthesizing ferroelectrics by forming polar structures by SCSCT,but also realizes the reversibility of SCSCT,which provides ideas for the construction and exploration of new molecular ferroelectrics.
基金supported by the program of Future Hydrogen Original Technology Development(2021M3I3A1084747),through the National Research Foundation of Korea(NRF)funded by the Korean government(Ministry of Science and ICT(MSIT))by the NRF grant funded by the Korea government(MSIT)(No.2020R1A2C1005590)。
文摘BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.
基金financially supported by the National Natural Science Foundation of China(Nos.51602286,51472218,51302247,51232006,and 21102212)the Science Foundation of Zhejiang Sci-Tech University(No.15022084-Y)the Natural Science Foundation of Zhejiang province(No.LY18E010004)
文摘Perovskite BaTiO3 （BTO） nanocrystals with a size of 150-200 nm have successfully been synthesized via a facile hydrothermal method by employing titanate nanowires as synthetic precursor. Tetragonality and spontaneous ferroelectric polarization of BTO nanocrystals have been determined by X-ray diffraction and transmission electron microscopy investigations. BTO nanocrystals loaded with Pt nanoparticles in a size of 2-5 nm have been explored as a catalyst towards CO oxidation to CO2. It is interesting to find that CO catalytic conversion rate over Pt-BTO nanocrystals gradually decreased and further increased near 100 ℃ when the catalytic temperature keeps increasing, whereas the conversion behavior in oxides is expected to be enhanced upon the catalytic temperature grows. Using differential scanning calorimetry and first-principle calculations, the observed catalytic behavior has been discussed on the basis of the ferroelectric polarization effect and the ferroelectric-paraelectric transition of BTO nanocrystals with a Curie temperature of 110 ℃. Below Curie temperature, CO catalytic oxidation could be significantly tailored by ferroelectric polarization of BTO nanocrystals via a promoted dissociation of O2 molecules. The findings suggest that a ferroelectric polarization in perovskite oxides could be an alternative way to modify the CO catalytic oxidation.
基金supported by the National Higher Education Institution General Research and Development Funding under Grant No.ZYGX2012J034National Basic Research Program of China(973)under Grants No.2015CB358600 and No.2013CB933801
文摘Hybrid organic-inorganic perovskites （e.g. CH;NH;PbI;） have attracted tremendous attention due to their promise for achieving next-generation cost-effective and high performance optoelectronic devices.These hybrid organic-inorganic perovskites possess excellent optical and electronic properties, including strong light absorption, high carrier abilities, optimized charge diffusion lengths, and reduced charge recombination etc., leading to their widespread applications in advanced solar energy technologies （e.g.high efficiency perovskite solar cells）. However, there is still a lack of investigations regarding fundamental properties such as ferroelectricity in these perovskites.As conventional ferroelectric ceramics are prepared at high temperature and have no mechanically flexibility,low-temperature proceed and flexible perovskite ferroelectrics have become promising candidates and should be exploited for future flexible ferroelectric applications. Here, ferroelectric properties in hybrid organic-inorganic perovskites and several state-of-the-art perovskite ferroelectrics are reviewed. Novel ferroelectric applications of hybrid organic-inorganic perovskites are discussed as well, providing guideline for realizing future high performance and flexible ferroelectric devices.
基金financial support by the Extramural Research and Intellectual Property Rights(ER&IPR),Defence Research and Development Organisation(DRDO),New Delhi,India(No.ERIP/ER/0903830/M/01/1235)
文摘Sr^2＋ modified polycrystalline PZT-PMN ceramics were synthesized by a semi-wet route. Impedance spectroscopy studies indicate the bulk and grain boundary effects of PZT-PMN material along with the negative temperature coefficient of resistance. The bulk conductiv-ity exhibits an Arrhenius-type thermally activated hopping process which is supported by the AC conductivity behavior as a function of fre-quency and temperature. It is observed that the remnant polarization increases with an increase in the Sr2＋content in PZT-PMN.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62174059 and 52250281)the Science and Technology Projects of Guangzhou Province of China (Grant No.202201000008)+1 种基金the Guangdong Science and Technology Project-International Cooperation (Grant No.2021A0505030064)the Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials (Grant No.2020B1212060066)。
文摘The discovery of ferroelectricity in HfO_(2) based materials reactivated the research on ferroelectric memory.However,the complete mechanism underlying its ferroelectricity remains to be fully elucidated.In this study,we conducted a systematic study on the microstructures and ferroelectric properties of Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films with various annealing rates in the rapid thermal annealing.It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size,reduced surface roughness and a higher portion of orthorhombic phase.Moreover,these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates.The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films,which was weakened with decreasing annealing rate.Our findings revealed that this internal stress,along with the stress originating from the top/bottom electrode,plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films.By carefully controlling the annealing rate,we could effectively regulate the tension stress within HZO thin films,thus achieving precise control over their ferroelectric properties.This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.
基金The project supported by the National Natural Science Foundation of China(10025209,10132010 90208002)the Research Grants of the Council of the Hong Kong Special Administrative Region,China(HKU7086/02E)the Key Grant Project of the Chinese Ministr
文摘A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation instability. The problems of mesh sensitivity and convergence, and the efficiency of the proposed nonlinear FE technique have been assessed to illustrate the versatility and potential accuracy of the said technique. The nonlinear electromechanical behavior, such as the hysteresis loops and butterfly curves, of ferroelectric ceramics subjected to both a uniform electric field and a point electric potential has been studied numerically. The results obtained are in good agreement with those of the corresponding theoretical and experimental analyses. Furthermore, the electromechanical coupling fields near （a） the boundary of a circular hole, （b） the boundary of an elliptic hole and （c） the tip of a crack, have been analyzed using the proposed nonlinear finite element method （FEM）. The proposed nonlinear electromechanically coupled FEM is useful for the analysis of domain switching, deformation and fracture of ferroelectric ceramics.
基金the National Natural Science Foundation of China(NSFC)(Grant No.12074126)the Foundation for Innovative Research Groups of NSFC(Grant No.51621001)the Fundamental Research Funds for the Central Universities(Grant No.2020ZYGXZR076).
文摘Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.
基金National Key R&D Program of China,Grant/Award Number:2022YFB3204000National Natural Science Foundation of China,Grant/Award Numbers:21825102,22235002,22161142022Fundamental Research Funds for the Central Universities,Grant/Award Number:FRF-IDRY-21-002。
文摘High-performance ferroelectric materials are widely used in various electronic devices owing to the function of mutual conversion among different energies,which mainly relates to their special structure gene of polarization configuration.Recent researches show that the high-entropy strategy has emerged as an effective and flexible approach for boosting physical properties in high-entropy ferroelectrics via the delicate design of local polarization configurations and other intrinsic effects caused by entropy increment,such as entropy stabilization,lattice disorder,inhibition of grain coarsening,improved mechanical properties,cocktail effect,and so on.In this review,the recent research progress about high-entropy ferroelectrics has been summarized,especially for the directional design of novel local polarization configurations according to the characteristics of different electrical properties such as high piezoelectricity,high-efficiency energy storage,and large electrostriction,providing a guidance for designing and exploring more novel local polarization configurations in high-entropy ferroelectrics for generating higher performance.
