Electrocaloric effect has attracted considerable attention for providing an eco-friendly and energy-efficient alternative to traditional vapor-compression refrigerators. In this review, we introduce theoretical explan...Electrocaloric effect has attracted considerable attention for providing an eco-friendly and energy-efficient alternative to traditional vapor-compression refrigerators. In this review, we introduce theoretical explanations of positive and negative electrocaloric effects along with their measurements. In particular, we review recent advancements in prototypes of electrocaloric refrigeration and present their current advantages and shortcomings. Finally, we discuss the potential applications of the electrocaloric effect such as clothing and metamaterials to provide insights into future research.展开更多
The reported electrocaloric(EC)effect in ferroelectrics is poised for application in the next generation of solidstate refrigeration technology,exhibiting substantial developmental potential.This study introduces a no...The reported electrocaloric(EC)effect in ferroelectrics is poised for application in the next generation of solidstate refrigeration technology,exhibiting substantial developmental potential.This study introduces a novel and efficient EC effect strategy in(1-x)Pb(Lu_(1/2)Nb_(1/2))O_(3)-xPbTiO_(3)(PLN-xPT)ceramics for low electric-fielddriven devices.Phase-field simulations provide fundamental insights into thermally induced continuous phase transitions,guiding subsequent experimental investigations.A comprehensive composition/temperature-driven phase evolution diagram is constructed,elucidating the sequential transformation from ferroelectric(FE)to antiferroelectric(AFE)and finally to paraelectric(PE)phases for x=0.10-0.18 components.Direct measurements of EC performance highlight x=0.16 as an outstanding performer,exhibiting remarkable properties,including an adiabatic temperature change(ΔT)of 3.03 K,EC strength(ΔT/ΔE)of 0.08 K cm kV-1,and a temperature span(Tspan)of 31℃.The superior EC effect performance is attributed to the temperature-induced FE to AFE transition at low electric fields and diffusion phase transition behavior contributing to the wide Tspan.This work provides valuable insights into developing high-performance EC effect across broad temperature ranges through the strategic design of continuous phase transitions,offering a simplified and economical approach for advancing ecofriendly and efficient solid-state cooling technologies.展开更多
Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small vol...Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small volume without the induced greenhouse effect or serious harm to ozone layer in the exploited refrigerants. However, low electrocaloric strength in nanocomposite dielectric is severely restricting its wide-spread application because of high applied operating voltage to improve electrocaloric effect. After addressing the chosen optimized ferroelectric ceramic and ferroelectric polymer matrix in conjunction with the analysis of crucial parameters, recent progress of electrocaloric effect(ECE) in polymer nanocomposites has been considerably reviewed. Subsequently, prior to proposing the conceptual design and devices/systems in electrocaloric nanocomposites, the existing developed devices/systems are reviewed. Finally, conclusions and prospects are conducted, including the aspects of materials chosen, structural design and key issues to be considered in improving electrocaloric effect of polymer nanocomposite dielectrics for flexible solidstate cooling devices.展开更多
Our societies are highly dependent on reliable cooling for air conditioning(AC)and refrigeration.Currently,modern cooling is supported by a 19th century technology:vapor compression cycle(VCC)-based cooling.Refrigeran...Our societies are highly dependent on reliable cooling for air conditioning(AC)and refrigeration.Currently,modern cooling is supported by a 19th century technology:vapor compression cycle(VCC)-based cooling.Refrigerants used in the VCC cooling are strong greenhouse gases and thus are among the leading causes of global warming.The electrocaloric(EC)cooling is attractive as an alternative to the VCC cooling.EC cooling is environmentally benign,compressor-free,highly scalable,and has the potential of achieving higher efficiency than VCC cooling.The active EC materials research since the late 2000s has created several EC materials that exhibit giant electrocaloric effect(ECE)(by direct measurement).These EC materials have enabled the demonstration of EC cooling devices that exhibit temperature lifts of more than 8 K.These EC materials and device research reveals the promise of fer-roelectric materials in generating giant ECE at low electric fields and EC cooling devices achieving high performance.This review highlights these advances and offers perspectives of the EC cooling technologies.展开更多
The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTi03 thin films at room temper- ature is investigated using the Ginzburg^Landau Devonshire thermodynamic theory. Numerical calculation...The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTi03 thin films at room temper- ature is investigated using the Ginzburg^Landau Devonshire thermodynamic theory. Numerical calculations indicate that the misfit strain has a large impact on the ferroelectric polarization states and the electrocaloric effect. Most importantly, the electrocaloric effect in the polydomain ca1/ca2/ca1/ea2 phase is much larger than that in the mon- odomain c phase and the other polydomain phases. Consequently, a large electrocaloric effect can be obtained by carefully controlling the misfit strain, which may provide potential applications in refrigeration devices.展开更多
The electrocaloric effect of the model ferroelectric BaTiO3was investigated using phenomenological theory. The results indicate that the applied electric field strength is a key factor for the induced electrocaloric r...The electrocaloric effect of the model ferroelectric BaTiO3was investigated using phenomenological theory. The results indicate that the applied electric field strength is a key factor for the induced electrocaloric response and there are two distinguishing electrocaloric responses. When a moderate electric field is applied, the electrocaloric temperature variation is small but the electrocaloric strength is high. In contrast, the electrocaloric temperature variation is large but electrocaloric strength is low when a very high electric field is applied. These results are consistent with the experimental observations on BaTiO3based bulk and thin film ferroelectric materials.展开更多
A Landau-Devonshire thermodynamic theory is employed to investigate the effects of composition and misfit strain on the room-temperature electrocaloric effect of epitaxial Pbl-xSrxTiO3 thin films. The ＂temperature-mi...A Landau-Devonshire thermodynamic theory is employed to investigate the effects of composition and misfit strain on the room-temperature electrocaloric effect of epitaxial Pbl-xSrxTiO3 thin films. The ＂temperature-misfit strain＂ phase diagrams with the Sr composition x of 0.1, 0.3, and 0.5 are constructed. The introduction of Sr composition reduces the Curie temperature greatly, and enhances the electrocaloric effect. Moreover, the electrocaloric effect largely depends on the misfit strain. Therefore, the Sr composition and the misfit strain can be controlled to obtain the giant room-temperature electrocaloric effect.展开更多
The electrocaloric effect in thin films of an electrocaloric material has the potential to be used for efficient cooling systems for high power electronic devices. We numerically calculated the effect of parameters in...The electrocaloric effect in thin films of an electrocaloric material has the potential to be used for efficient cooling systems for high power electronic devices. We numerically calculated the effect of parameters in electrocaloric refrigeration with a thermal switch of fluid motion on the thermal performance. The system of changing air and water flow with the pulse generation of cold energy increased the heat transfer efficiency to 67% at a frequency of 5 Hz. The optimum time delay of water flow to increase the heat transfer efficiency was zero at low frequency and became half of the time period to change heat for a high frequency of 100 Hz. When the heat transfer efficiency was high, the final temperature change in water flow was not the maximum temperature change.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
Composition dependence of electrocaloric effect is investigated in(1- x)Pb(Mg1/3Nb2/3)O3- xP b Ti O3 single crystals by using an eighth-order Landau–Devonshire theory. The applied electric field along [001] direction...Composition dependence of electrocaloric effect is investigated in(1- x)Pb(Mg1/3Nb2/3)O3- xP b Ti O3 single crystals by using an eighth-order Landau–Devonshire theory. The applied electric field along [001] direction reduces the ferroelectric-ferroelectric phase transition temperatures, but increases the Curie temperatures. The electrocaloric coefficients of tetragonal phase are much larger than that of rhombohedral and monoclinic phase. A negative electrocaloric effect is observed near the MC-T phase transition in 0.69Pb(Mg1/3Nb2/3)O3-0.31 Pb Ti O3 single crystal. The application of a strong enough electric field results in a high adiabatic temperature change over a broad range of temperature.Therefore, it would be useful to construct a solid state cooling cycle over a broad temperature range for practical applications.展开更多
The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric cur...The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric current, and heat capacity are used to systematically investigate the electrocaloric performances of EA2CuCl4. The pyroelectric currents are measured under various voltages, and the electrocaloric effect(ECE) is calculated. Its ECE exhibits an isothermal entropy change of 0.0028 J/kg·K under an electric field of 30 kV/cm associated with a relatively broad temperature span. Further, the maximum pyroelectric coefficient(p) is 4× 10^-3 C/m^2·K and the coefficient β for generating ECE from electric displacement D is 1.068× 10^8 J·cm·K^-1·C^-2 at 240 K. Our results indicate that the ECE behavior of organic–inorganic hybrid EA2CuCl4 is in accordance with Jona and Shirane’s opinion in which the ECE should occur both below and above the Curie temperature Tc.展开更多
A thrust for looking multifunctional materials for applications in civil engineering structures has attracted interest among researchers across the globe.Cement based Ba0.85Ca0.15Zr0.1Ti0.88Sn0.02O3(BCZT.Sn)composites...A thrust for looking multifunctional materials for applications in civil engineering structures has attracted interest among researchers across the globe.Cement based Ba0.85Ca0.15Zr0.1Ti0.88Sn0.02O3(BCZT.Sn)composites were prepared for electrocaloric applications with varying BCZT.Sn to cement ratio.Hysteresis loops showed some signature of saturation in cement composites.However,loops of pure sample were saturated due to its ferroelectric nature.Furthermore,these composites were explored for the first time in solid state refrigeration technology namely electrocaloric effect(ECE).Peak electrocaloric performance shows an adiabatic temperature changes of 0.71,0.64 and 0.50 K and isothermal entropy changes of 0.86,0.80 and 0.65 J/(kg.K)for BCZT.Sn,10%and 15%cement composites,respectively,under application of 0-29 kV/cm electric field.The adiabatic temperature change in cement based composites is comparable with that of the BCZT-Sn ferroelectric ceramics.Furthermore,the dielectric constant(εr)of composites with different ceramic contents at room temperature reveals that dielectric constant increases with an increase in BCZT-Sn proportion in composites.These cement based BCZT.Sn composite materials may be used in solid state refrigeration as they are fairly competitive with the pristine sample.展开更多
A phenomenological thermodynamic theory is applied to investigate the effect of misfit strgin and electric field on the electrocaloric effect of P（VDF-TrFN）/SrTiO3 bilayer thin films. Theoretical results indicate th...A phenomenological thermodynamic theory is applied to investigate the effect of misfit strgin and electric field on the electrocaloric effect of P（VDF-TrFN）/SrTiO3 bilayer thin films. Theoretical results indicate that the low electric field results in the decrease of the average polarization with the increase of the relative thickness of SrTi03 layer, and the high electric field has an opposite effect on it. Moreover, the electroealoric effect strongly depends on the electric field. The low electric field and the small field change can lead to a maximum of the electrocaloric effect, meanwhile the high electric field or the large field change results in the opposite trend.展开更多
The electrocaloric effect of ferroelectric ceramics has been studied extensively for solid-state caloric cooling.Generally,most ferroelectric ceramics are poor thermal conductors.In this work,the possibility of enhanc...The electrocaloric effect of ferroelectric ceramics has been studied extensively for solid-state caloric cooling.Generally,most ferroelectric ceramics are poor thermal conductors.In this work,the possibility of enhancing the thermal conduction of ferroelectric ceramics through the electrocaloric effect is studied.A multilayer ceramic structure is proposed and the proper sequential electric field is applied to each ceramic layer.The result shows that the thermal conduction of the multilayer structure is significantly enhanced because of the electrocaloric effect of the ferroelectric ceramics.As a result,the work finds an alternatively way of applying the electrocaloric effect,prompting thermal conduction.展开更多
The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combini...The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that（i） it is reasonable to use zero-field CP,（ii） optimized ？T should be 2 K,（iii） it is better to keep △E 〈 EC, and（iv） E1〈 EC. Here, EC is the coercive field of material.展开更多
The electrocaloric effect (ECE) is defined as the fact that the temperature of dielectric material changes, when an electric field is applied to or removed from the material [1]. It might be a possible solution for th...The electrocaloric effect (ECE) is defined as the fact that the temperature of dielectric material changes, when an electric field is applied to or removed from the material [1]. It might be a possible solution for the increasing energy consumption for thermal management because of its high effectiveness. Previous research on the ECE has investigated several possible methods to build a model based on ECE and feasibilities to increase the efficiency of the model. But there has been no study on all the factors that may affect the performance of the device. Thus, in this paper, we designed a cooling device based on ECE and simulated it by using the control variates method showing that a high efficiency can be reached through stated model.展开更多
The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTiO 3 thin films at room temperature is investigated using the Ginzburg–Landau–Devonshire thermodynamic theory. Numerical calculatio...The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTiO 3 thin films at room temperature is investigated using the Ginzburg–Landau–Devonshire thermodynamic theory. Numerical calculations indicate that the misfit strain has a large impact on the ferroelectric polarization states and the electrocaloric effect. Most importantly, the electrocaloric effect in the polydomain ca 1 /ca 2 /ca 1 /ca 2 phase is much larger than that in the monodomain c phase and the other polydomain phases. Consequently, a large electrocaloric effect can be obtained by carefully controlling the misfit strain, which may provide potential applications in refrigeration devices.展开更多
Electrocaloric(EC)refrigeration,which employs ferroelectric(FE)ceramics as a working medium,is regarded as a promising green refrigeration technology that could potentially replace vapor-compression refrigeration.One ...Electrocaloric(EC)refrigeration,which employs ferroelectric(FE)ceramics as a working medium,is regarded as a promising green refrigeration technology that could potentially replace vapor-compression refrigeration.One of the principal considerations in EC application is the capacity to attain high EC strength near room temperature.In this work,we investigated the EC effect in Sm/Mn co-doped BaTiO_(3)[(Ba_(1-1.5x)Sm_(x))(Ti_(0.99)Mn_(0.01))O_(3)]ceramics.As the smallest trivalent ion that can totally occupy the A site,Sm^(3+)is not only capable of shifting the Curie temperature but also of optimizing the EC effect.Furthermore,the introduction of the Mn element into the matrix results in the formation of defect dipoles,which also serves to enhance the EC performance.Therefore,large EC strengths of △T/△E=0.49Kmm kV^(-1)(@51℃),0.34Kmm kV^(-1)(@39℃)and 0.21Kmm kV^(-1)(@30℃)were,respectively,achieved in x=0.05-0.07 ceramics,demonstrating the potential for future refrigeration applications.展开更多
The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions....The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions.This research unveils a remarkable ECE in afinely tuned(Ba_(0.86)Ca_(0.14))_(0.98)La_(0.02)Ti_(0.92)Sn_(0.08)O_(3)ceramic,exhibiting a temperature shift(DT)of 1.6 K across more than 85%of the maximumΔT(ΔT_(max))and spanning an exceptionally wide operational range of 92 K.Our investigation on dielectric responses and ferroelectric polarization-electricfield(PeE)loops suggests that the broad operational scope results from the fragmentation of extended ferroelectric domains into smaller domains and polar nano-regions(PNRs)supported by PFM analysis.Furthermore,the introduction of La enhances spontaneous polarization by significantly extending the maximum electricfield that can be applied,facilitating highperformance ECE at ambient temperature.This study positions BaTiO_(3)-based lead-free ceramic as a sustainable alternative for addressing the cooling demands of modern electronic components,marking a significant stride toward next-generation solid-state refrigeration.展开更多
The increasing demand for effective and environmentally compatible cooling technologies has driven significant interest in the development of solid-state cooling materials.Among these,the electrocaloric(EC)system is c...The increasing demand for effective and environmentally compatible cooling technologies has driven significant interest in the development of solid-state cooling materials.Among these,the electrocaloric(EC)system is considered a promising solid-state cooling method,offering advantages over other cooling technologies,such as low environmental impact,cost-effectiveness,high energy efficiency,and compact device size.To fully harness the potential of EC materials,multilayer ceramic capacitors(MLCCs)have emerged as effective and appropriate structures for EC cooling applications.This article provides a comprehensive review of recent advancements and research trends in MLCC-based EC materials,including the fundamentals of the EC effect,the performance of MLCC-based EC materials,EC effect(ECE)measurement,multilayer geometric structure design,and cooling device design based on MLCCs.A comparison of different systems of EC materials,along with an exploration of microstructure improvement,was conducted based on recent studies.A special focus was placed on multilayer structure design for EC performance enhancement,followed by reviewing two types of EC cooling device designs.The review offers insights into the fabrication and characterization of MLCC-based EC materials,offering guidance for future developments in EC material research and practical applications.展开更多
基金funding from the National Natural Science Foundation of China (Grant Nos. 12035004 and 12320101004)the Innovation Program of the Shanghai Municipal Education Commission (Grant No. 2023ZKZD06)。
文摘Electrocaloric effect has attracted considerable attention for providing an eco-friendly and energy-efficient alternative to traditional vapor-compression refrigerators. In this review, we introduce theoretical explanations of positive and negative electrocaloric effects along with their measurements. In particular, we review recent advancements in prototypes of electrocaloric refrigeration and present their current advantages and shortcomings. Finally, we discuss the potential applications of the electrocaloric effect such as clothing and metamaterials to provide insights into future research.
基金financially supported by the National Natural Science Foundation of China(Grant No.52261135548)the Key Research and Development Program of Shaanxi(Program No.2022KWZ-22)+2 种基金The research was made possible by Russian Science Foundation(Project No.23-42-00116)The equipment of the Ural Center for Shared Use“Modern nanotechnology”Ural Federal University(Reg.No.2968)which is supported by the Ministry of ScienceHigher Education RF(Project No.075-15-2021-677)was used.
文摘The reported electrocaloric(EC)effect in ferroelectrics is poised for application in the next generation of solidstate refrigeration technology,exhibiting substantial developmental potential.This study introduces a novel and efficient EC effect strategy in(1-x)Pb(Lu_(1/2)Nb_(1/2))O_(3)-xPbTiO_(3)(PLN-xPT)ceramics for low electric-fielddriven devices.Phase-field simulations provide fundamental insights into thermally induced continuous phase transitions,guiding subsequent experimental investigations.A comprehensive composition/temperature-driven phase evolution diagram is constructed,elucidating the sequential transformation from ferroelectric(FE)to antiferroelectric(AFE)and finally to paraelectric(PE)phases for x=0.10-0.18 components.Direct measurements of EC performance highlight x=0.16 as an outstanding performer,exhibiting remarkable properties,including an adiabatic temperature change(ΔT)of 3.03 K,EC strength(ΔT/ΔE)of 0.08 K cm kV-1,and a temperature span(Tspan)of 31℃.The superior EC effect performance is attributed to the temperature-induced FE to AFE transition at low electric fields and diffusion phase transition behavior contributing to the wide Tspan.This work provides valuable insights into developing high-performance EC effect across broad temperature ranges through the strategic design of continuous phase transitions,offering a simplified and economical approach for advancing ecofriendly and efficient solid-state cooling technologies.
基金Project(202045007) supported by the Start-up Funds for Outstanding Talents in Central South University,China。
文摘Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small volume without the induced greenhouse effect or serious harm to ozone layer in the exploited refrigerants. However, low electrocaloric strength in nanocomposite dielectric is severely restricting its wide-spread application because of high applied operating voltage to improve electrocaloric effect. After addressing the chosen optimized ferroelectric ceramic and ferroelectric polymer matrix in conjunction with the analysis of crucial parameters, recent progress of electrocaloric effect(ECE) in polymer nanocomposites has been considerably reviewed. Subsequently, prior to proposing the conceptual design and devices/systems in electrocaloric nanocomposites, the existing developed devices/systems are reviewed. Finally, conclusions and prospects are conducted, including the aspects of materials chosen, structural design and key issues to be considered in improving electrocaloric effect of polymer nanocomposite dielectrics for flexible solidstate cooling devices.
基金supported by the U.S.Office of Naval Research under awards number N00014-19-1-2028 and N00014-23-1-2247.
文摘Our societies are highly dependent on reliable cooling for air conditioning(AC)and refrigeration.Currently,modern cooling is supported by a 19th century technology:vapor compression cycle(VCC)-based cooling.Refrigerants used in the VCC cooling are strong greenhouse gases and thus are among the leading causes of global warming.The electrocaloric(EC)cooling is attractive as an alternative to the VCC cooling.EC cooling is environmentally benign,compressor-free,highly scalable,and has the potential of achieving higher efficiency than VCC cooling.The active EC materials research since the late 2000s has created several EC materials that exhibit giant electrocaloric effect(ECE)(by direct measurement).These EC materials have enabled the demonstration of EC cooling devices that exhibit temperature lifts of more than 8 K.These EC materials and device research reveals the promise of fer-roelectric materials in generating giant ECE at low electric fields and EC cooling devices achieving high performance.This review highlights these advances and offers perspectives of the EC cooling technologies.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10904053)the Jiangsu Provincial Natural Science Foundation for Colleges and Universities, China (Grant No. 09KJB140002)+1 种基金the Priority Academic Development Program of Jiangsu Higher Education InstitutionsQing Lan Project, China
文摘The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTi03 thin films at room temper- ature is investigated using the Ginzburg^Landau Devonshire thermodynamic theory. Numerical calculations indicate that the misfit strain has a large impact on the ferroelectric polarization states and the electrocaloric effect. Most importantly, the electrocaloric effect in the polydomain ca1/ca2/ca1/ea2 phase is much larger than that in the mon- odomain c phase and the other polydomain phases. Consequently, a large electrocaloric effect can be obtained by carefully controlling the misfit strain, which may provide potential applications in refrigeration devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.11704242)the Natural Science Foundation of Shanghai,China(Grant No.17ZR1447200)
文摘The electrocaloric effect of the model ferroelectric BaTiO3was investigated using phenomenological theory. The results indicate that the applied electric field strength is a key factor for the induced electrocaloric response and there are two distinguishing electrocaloric responses. When a moderate electric field is applied, the electrocaloric temperature variation is small but the electrocaloric strength is high. In contrast, the electrocaloric temperature variation is large but electrocaloric strength is low when a very high electric field is applied. These results are consistent with the experimental observations on BaTiO3based bulk and thin film ferroelectric materials.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10904053)the Natural Science Foundation for Colleges and Universities of Jiangsu Province, China (Grant No. 09KJB140002)the Priority Academic Program Development of Jiangsu Higher Education Institutions and Qing Lan Project
文摘A Landau-Devonshire thermodynamic theory is employed to investigate the effects of composition and misfit strain on the room-temperature electrocaloric effect of epitaxial Pbl-xSrxTiO3 thin films. The ＂temperature-misfit strain＂ phase diagrams with the Sr composition x of 0.1, 0.3, and 0.5 are constructed. The introduction of Sr composition reduces the Curie temperature greatly, and enhances the electrocaloric effect. Moreover, the electrocaloric effect largely depends on the misfit strain. Therefore, the Sr composition and the misfit strain can be controlled to obtain the giant room-temperature electrocaloric effect.
文摘The electrocaloric effect in thin films of an electrocaloric material has the potential to be used for efficient cooling systems for high power electronic devices. We numerically calculated the effect of parameters in electrocaloric refrigeration with a thermal switch of fluid motion on the thermal performance. The system of changing air and water flow with the pulse generation of cold energy increased the heat transfer efficiency to 67% at a frequency of 5 Hz. The optimum time delay of water flow to increase the heat transfer efficiency was zero at low frequency and became half of the time period to change heat for a high frequency of 100 Hz. When the heat transfer efficiency was high, the final temperature change in water flow was not the maximum temperature change.
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Supported by the State Key Program of National Natural Science of China under Grant No.51335002Changzhou Science and Technology Project under Grant No.CJ20130022the Priority Academic Program Development of Jiangsu Higher Education Institutions on Renewable Energy Material Science and Engineering
文摘Composition dependence of electrocaloric effect is investigated in(1- x)Pb(Mg1/3Nb2/3)O3- xP b Ti O3 single crystals by using an eighth-order Landau–Devonshire theory. The applied electric field along [001] direction reduces the ferroelectric-ferroelectric phase transition temperatures, but increases the Curie temperatures. The electrocaloric coefficients of tetragonal phase are much larger than that of rhombohedral and monoclinic phase. A negative electrocaloric effect is observed near the MC-T phase transition in 0.69Pb(Mg1/3Nb2/3)O3-0.31 Pb Ti O3 single crystal. The application of a strong enough electric field results in a high adiabatic temperature change over a broad range of temperature.Therefore, it would be useful to construct a solid state cooling cycle over a broad temperature range for practical applications.
基金Project supported by the Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No.FJCXY18040303)the Youth Innovation Promotion of the Chinese Academy of Sciences(Grant No.2013004)the National Natural Science Foundation of China(Grant Nos.51676198 and 51771067)
文摘The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric current, and heat capacity are used to systematically investigate the electrocaloric performances of EA2CuCl4. The pyroelectric currents are measured under various voltages, and the electrocaloric effect(ECE) is calculated. Its ECE exhibits an isothermal entropy change of 0.0028 J/kg·K under an electric field of 30 kV/cm associated with a relatively broad temperature span. Further, the maximum pyroelectric coefficient(p) is 4× 10^-3 C/m^2·K and the coefficient β for generating ECE from electric displacement D is 1.068× 10^8 J·cm·K^-1·C^-2 at 240 K. Our results indicate that the ECE behavior of organic–inorganic hybrid EA2CuCl4 is in accordance with Jona and Shirane’s opinion in which the ECE should occur both below and above the Curie temperature Tc.
文摘A thrust for looking multifunctional materials for applications in civil engineering structures has attracted interest among researchers across the globe.Cement based Ba0.85Ca0.15Zr0.1Ti0.88Sn0.02O3(BCZT.Sn)composites were prepared for electrocaloric applications with varying BCZT.Sn to cement ratio.Hysteresis loops showed some signature of saturation in cement composites.However,loops of pure sample were saturated due to its ferroelectric nature.Furthermore,these composites were explored for the first time in solid state refrigeration technology namely electrocaloric effect(ECE).Peak electrocaloric performance shows an adiabatic temperature changes of 0.71,0.64 and 0.50 K and isothermal entropy changes of 0.86,0.80 and 0.65 J/(kg.K)for BCZT.Sn,10%and 15%cement composites,respectively,under application of 0-29 kV/cm electric field.The adiabatic temperature change in cement based composites is comparable with that of the BCZT-Sn ferroelectric ceramics.Furthermore,the dielectric constant(εr)of composites with different ceramic contents at room temperature reveals that dielectric constant increases with an increase in BCZT-Sn proportion in composites.These cement based BCZT.Sn composite materials may be used in solid state refrigeration as they are fairly competitive with the pristine sample.
基金Supported by the National Natural Science Foundation of China under Grant No. 10904053Sponsored by the Priority Academic Program Development of Jiangsu Higher Education Institutions and Qing Lan Project
文摘A phenomenological thermodynamic theory is applied to investigate the effect of misfit strgin and electric field on the electrocaloric effect of P（VDF-TrFN）/SrTiO3 bilayer thin films. Theoretical results indicate that the low electric field results in the decrease of the average polarization with the increase of the relative thickness of SrTi03 layer, and the high electric field has an opposite effect on it. Moreover, the electroealoric effect strongly depends on the electric field. The low electric field and the small field change can lead to a maximum of the electrocaloric effect, meanwhile the high electric field or the large field change results in the opposite trend.
基金the National Natural Science Foundation of China(Grant No.11704242)the Natural Science Foundation of Shanghai,China(Grant No.17ZR1447200).
文摘The electrocaloric effect of ferroelectric ceramics has been studied extensively for solid-state caloric cooling.Generally,most ferroelectric ceramics are poor thermal conductors.In this work,the possibility of enhancing the thermal conduction of ferroelectric ceramics through the electrocaloric effect is studied.A multilayer ceramic structure is proposed and the proper sequential electric field is applied to each ceramic layer.The result shows that the thermal conduction of the multilayer structure is significantly enhanced because of the electrocaloric effect of the ferroelectric ceramics.As a result,the work finds an alternatively way of applying the electrocaloric effect,prompting thermal conduction.
基金Project supported by the Natural Science Foundation of Shanghai,China(Grant No.17ZR1447200)
文摘The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that（i） it is reasonable to use zero-field CP,（ii） optimized ？T should be 2 K,（iii） it is better to keep △E 〈 EC, and（iv） E1〈 EC. Here, EC is the coercive field of material.
文摘The electrocaloric effect (ECE) is defined as the fact that the temperature of dielectric material changes, when an electric field is applied to or removed from the material [1]. It might be a possible solution for the increasing energy consumption for thermal management because of its high effectiveness. Previous research on the ECE has investigated several possible methods to build a model based on ECE and feasibilities to increase the efficiency of the model. But there has been no study on all the factors that may affect the performance of the device. Thus, in this paper, we designed a cooling device based on ECE and simulated it by using the control variates method showing that a high efficiency can be reached through stated model.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10904053)the Jiangsu Provincial Natural Science Foundation for Colleges and Universities, China (Grant No. 09KJB140002)+1 种基金the Priority Academic Development Program of Jiangsu Higher Education InstitutionsQing Lan Project, China
文摘The effect of misfit strain on the electrocaloric effect in polydomain epitaxial BaTiO 3 thin films at room temperature is investigated using the Ginzburg–Landau–Devonshire thermodynamic theory. Numerical calculations indicate that the misfit strain has a large impact on the ferroelectric polarization states and the electrocaloric effect. Most importantly, the electrocaloric effect in the polydomain ca 1 /ca 2 /ca 1 /ca 2 phase is much larger than that in the monodomain c phase and the other polydomain phases. Consequently, a large electrocaloric effect can be obtained by carefully controlling the misfit strain, which may provide potential applications in refrigeration devices.
基金supported by the Sichuan Science and Technology Program(No.2023NSFSC0975)National Natural Science Foundation of China(Nos.52302134 and 52302135)+1 种基金Scientific Research Foundation of Chengdu University of Information Technology(No.KYTZ202246)open research fund of the Sichuan Province Key Laboratory of Information Materials and Devices Application(No.2023XXCL003).
文摘Electrocaloric(EC)refrigeration,which employs ferroelectric(FE)ceramics as a working medium,is regarded as a promising green refrigeration technology that could potentially replace vapor-compression refrigeration.One of the principal considerations in EC application is the capacity to attain high EC strength near room temperature.In this work,we investigated the EC effect in Sm/Mn co-doped BaTiO_(3)[(Ba_(1-1.5x)Sm_(x))(Ti_(0.99)Mn_(0.01))O_(3)]ceramics.As the smallest trivalent ion that can totally occupy the A site,Sm^(3+)is not only capable of shifting the Curie temperature but also of optimizing the EC effect.Furthermore,the introduction of the Mn element into the matrix results in the formation of defect dipoles,which also serves to enhance the EC performance.Therefore,large EC strengths of △T/△E=0.49Kmm kV^(-1)(@51℃),0.34Kmm kV^(-1)(@39℃)and 0.21Kmm kV^(-1)(@30℃)were,respectively,achieved in x=0.05-0.07 ceramics,demonstrating the potential for future refrigeration applications.
基金the Science and Technology Plan of Guangxi(Nos.AA23023027,AB24010230)the Key Research and Development Program of Shandong Province(2022CXGC020203)+1 种基金the Natural Science Foundation of China(Grant No.12264012,62271362,12304120)the Science and Technology Plan of Guilin(2022H03 and ZY20220101).
文摘The electrocaloric effect(ECE)offers a pathway to environmentally sustainable and easily miniaturized refrigeration technology,positioning it as a front-runner for the next generation of solid-state cooling solutions.This research unveils a remarkable ECE in afinely tuned(Ba_(0.86)Ca_(0.14))_(0.98)La_(0.02)Ti_(0.92)Sn_(0.08)O_(3)ceramic,exhibiting a temperature shift(DT)of 1.6 K across more than 85%of the maximumΔT(ΔT_(max))and spanning an exceptionally wide operational range of 92 K.Our investigation on dielectric responses and ferroelectric polarization-electricfield(PeE)loops suggests that the broad operational scope results from the fragmentation of extended ferroelectric domains into smaller domains and polar nano-regions(PNRs)supported by PFM analysis.Furthermore,the introduction of La enhances spontaneous polarization by significantly extending the maximum electricfield that can be applied,facilitating highperformance ECE at ambient temperature.This study positions BaTiO_(3)-based lead-free ceramic as a sustainable alternative for addressing the cooling demands of modern electronic components,marking a significant stride toward next-generation solid-state refrigeration.
基金supports from the National Natural Science Foundation of China(Grant No.52272131)Fundamental Research Funds for the Central Universities(Grant No.2023JCCXJD04)+4 种基金China Scholarship Council scholarship(Grant No.201906435006)State Key Laboratory of New Ceramics and Fine Processing Tsinghua University(Grant Nos.KFZD201901,KF201910)Open Fund of State Key Laboratory of Coal Resources and Safe Mining(Grant No.SKLCRSM19KFA13)support through NSF I/UCRC:Center for Energy Harvesting Materials and Systems(CEHMS)support through National Science Foundation through the award number DMR-1936432.
文摘The increasing demand for effective and environmentally compatible cooling technologies has driven significant interest in the development of solid-state cooling materials.Among these,the electrocaloric(EC)system is considered a promising solid-state cooling method,offering advantages over other cooling technologies,such as low environmental impact,cost-effectiveness,high energy efficiency,and compact device size.To fully harness the potential of EC materials,multilayer ceramic capacitors(MLCCs)have emerged as effective and appropriate structures for EC cooling applications.This article provides a comprehensive review of recent advancements and research trends in MLCC-based EC materials,including the fundamentals of the EC effect,the performance of MLCC-based EC materials,EC effect(ECE)measurement,multilayer geometric structure design,and cooling device design based on MLCCs.A comparison of different systems of EC materials,along with an exploration of microstructure improvement,was conducted based on recent studies.A special focus was placed on multilayer structure design for EC performance enhancement,followed by reviewing two types of EC cooling device designs.The review offers insights into the fabrication and characterization of MLCC-based EC materials,offering guidance for future developments in EC material research and practical applications.
