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 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
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
Pb_(x)Sr_(1-x)TiO_(3)(x=0.30,0.35,0.40,0.45,0.50 and 0.55)ceramics were fabricated by a solid-state reaction route.Xeray diffraction data at room temperature show PST samples shift from cubic to tetragonal phase with ...Pb_(x)Sr_(1-x)TiO_(3)(x=0.30,0.35,0.40,0.45,0.50 and 0.55)ceramics were fabricated by a solid-state reaction route.Xeray diffraction data at room temperature show PST samples shift from cubic to tetragonal phase with the increase of Pb^(2+) content.The microstructures were observed by scanning electron microscopy.Dielectric measurement was employed to investigate the ferroelectriceparaelectric phase transition behavior.Temperature dependent polarizationeelectric field hysteresis loops were conducted to study the electrocaloric effect(ECE)of the ferroelectric ceramics by indirect methods over a wide temperature range.Direct measurement of temperature change(DT)at room temperature for all samples can achieve 0.79e1.86 K.What's more,a giant ECE(△T=2.05 K,EC strength(△T/△E)=0.51×10^(-6) K m/V,under 40 kV/cm)was obtained in the sample of x=0.35 near phase transition temperature.Our results suggest that the ceramics are promising cooling materials with excellent EC properties for energy related applications.展开更多
We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial mult...We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial multilayer capacitor based on doped BaTiO_(3).Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290 K characteristic for the relaxors.Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions.Good agreement was found between the values of△T_(AD) determined by direct and indirect measurements at the electric field up to 15.4 kV/cm.Quasi-isothermal conditions lead,firstly,to decrease of large△T_(AD)≈0.94 K obtained in adiabatic conditions under E=308 kV/cm to 0.87 K,and,secondly,the appearance of a difference between the values of △T^(ON) and△T^(OFF) determined when the electric field is applied and removed.Using this phenomenon and changing the frequency of the periodic electric field,E=15.4 kV/cm,the efect of cooling was obtained equal to[(OT^(ON)+AT^(OFF))/2]_(max)=-0.032 K.The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.展开更多
Ferroelectric(FE)phase transition with a large polarization change benefits to generate large electrocaloric(EC)effect for solid-sate and zero-carbon cooling application.However,most EC studies only focus on the singl...Ferroelectric(FE)phase transition with a large polarization change benefits to generate large electrocaloric(EC)effect for solid-sate and zero-carbon cooling application.However,most EC studies only focus on the single-physical factor associated phase transition.Herein,we initiated a comprehensive discussion on phase transition in Pb_(0.99)Nb_(0.02)[(Zr_(0.6)Sn_(0.4))1−xTix]_(0.98)O_(3)(PNZST100x)antiferroelectric(AFE)ceramic system under the joint action of multi-physical factors,including composition,temperature,and electric field.Due to low energy barrier and enhanced zero-field entropy,the multi-phase coexistence point(x=0.12)in the composition–temperature phase diagram yields a large positive EC peak of maximum temperature change(ΔT_(max))=2.44 K(at 40 kV/cm).Moreover,the electric field–temperature phase diagrams for four representative ceramics provide a more explicit guidance for EC evolution behavior.Besides the positive EC peaks near various phase transition temperatures,giant positive EC effects are also brought out by the electric field-induced phase transition from tetragonal AFE(AFET)to low-temperature rhombohedral FE(FER),which is reflected by a positive-slope boundary in the electric field–temperature phase diagram,while significant negative EC responses are generated by the phase transition from AFET to high-temperature multi-cell cubic paraelectric(PEMCC)with a negative-slope phase boundary.This work emphasizes the importance of phase diagram covering multi-physical factors for high-performance EC material design.展开更多
基于Laudau-Devonshire的热动力学模型,计算了Eu Ti O3铁电薄膜材料的电热效应.结果显示在外加应力的调控下,电极化、电热系数以及绝热温差都会随之变化.外加垂直于表面的张应力加大,薄膜的相变温度升高,绝热温差增加,最大绝热温差所对...基于Laudau-Devonshire的热动力学模型,计算了Eu Ti O3铁电薄膜材料的电热效应.结果显示在外加应力的调控下,电极化、电热系数以及绝热温差都会随之变化.外加垂直于表面的张应力加大,薄膜的相变温度升高,绝热温差增加,最大绝热温差所对应的工作温度向高温区移动.对于二维平面失配应变um-.的薄膜,当外加张应力σ33 GPa时,其最大电热系数为1.75×10-C/m2·K,电场变化200 MV/m时室温下绝热温差T的最大值可达到14 K以上,绝热温差T K的工作温区超过120 K,表明可以通过调控外部应力来获取室温时较大的绝热温差.此结果预示着铁电Eu Ti O3薄膜在室温固态制冷方面可能具有较好的应用前景.展开更多
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. 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.
基金the National Natural Science Foundation of China(Grant Nos.11574057 and 51604087)the Guangdong Provincial Natural Science Foundation of China(Grant No.2016A030313718)the Science and Technology Program of Guangdong Province of China(Grant Nos.2016A010104018,and 2017A010104022).
文摘Pb_(x)Sr_(1-x)TiO_(3)(x=0.30,0.35,0.40,0.45,0.50 and 0.55)ceramics were fabricated by a solid-state reaction route.Xeray diffraction data at room temperature show PST samples shift from cubic to tetragonal phase with the increase of Pb^(2+) content.The microstructures were observed by scanning electron microscopy.Dielectric measurement was employed to investigate the ferroelectriceparaelectric phase transition behavior.Temperature dependent polarizationeelectric field hysteresis loops were conducted to study the electrocaloric effect(ECE)of the ferroelectric ceramics by indirect methods over a wide temperature range.Direct measurement of temperature change(DT)at room temperature for all samples can achieve 0.79e1.86 K.What's more,a giant ECE(△T=2.05 K,EC strength(△T/△E)=0.51×10^(-6) K m/V,under 40 kV/cm)was obtained in the sample of x=0.35 near phase transition temperature.Our results suggest that the ceramics are promising cooling materials with excellent EC properties for energy related applications.
基金funded by Russian Foundation for Basic Research,Government of Krasnoyarsk Territory,Krasnoyarsk Region Science and Technology Support Fund to the research,project no.16-42-240428 r_apartially financially supported by Government of Russian Federation,Grant 074-U01.
文摘We present the results of studies of thermal expansion,heat capacity,permittivity,polarization and the influence of different thermal conditions on the intensive electrocaloric ffect(ECE),△T_(AD),in a commercial multilayer capacitor based on doped BaTiO_(3).Investigations in a wide temperature range revealed one anomaly in the behavior of the physical properties at about 290 K characteristic for the relaxors.Direct measurements showed a high reversibility of ECE under equilibrium thermal conditions.Good agreement was found between the values of△T_(AD) determined by direct and indirect measurements at the electric field up to 15.4 kV/cm.Quasi-isothermal conditions lead,firstly,to decrease of large△T_(AD)≈0.94 K obtained in adiabatic conditions under E=308 kV/cm to 0.87 K,and,secondly,the appearance of a difference between the values of △T^(ON) and△T^(OFF) determined when the electric field is applied and removed.Using this phenomenon and changing the frequency of the periodic electric field,E=15.4 kV/cm,the efect of cooling was obtained equal to[(OT^(ON)+AT^(OFF))/2]_(max)=-0.032 K.The results obtained are useful for further development of the electrocaloric refrigeration technique without thermal switches.
基金supported by the National Natural Science Foundation of China(52173217)the National Key R&D Program of China(2018YFB0704301),and 111 project(B170003).
文摘Ferroelectric(FE)phase transition with a large polarization change benefits to generate large electrocaloric(EC)effect for solid-sate and zero-carbon cooling application.However,most EC studies only focus on the single-physical factor associated phase transition.Herein,we initiated a comprehensive discussion on phase transition in Pb_(0.99)Nb_(0.02)[(Zr_(0.6)Sn_(0.4))1−xTix]_(0.98)O_(3)(PNZST100x)antiferroelectric(AFE)ceramic system under the joint action of multi-physical factors,including composition,temperature,and electric field.Due to low energy barrier and enhanced zero-field entropy,the multi-phase coexistence point(x=0.12)in the composition–temperature phase diagram yields a large positive EC peak of maximum temperature change(ΔT_(max))=2.44 K(at 40 kV/cm).Moreover,the electric field–temperature phase diagrams for four representative ceramics provide a more explicit guidance for EC evolution behavior.Besides the positive EC peaks near various phase transition temperatures,giant positive EC effects are also brought out by the electric field-induced phase transition from tetragonal AFE(AFET)to low-temperature rhombohedral FE(FER),which is reflected by a positive-slope boundary in the electric field–temperature phase diagram,while significant negative EC responses are generated by the phase transition from AFET to high-temperature multi-cell cubic paraelectric(PEMCC)with a negative-slope phase boundary.This work emphasizes the importance of phase diagram covering multi-physical factors for high-performance EC material design.
基金National Natural Science Foundation of China(11604354,11774366)Chinese Academy of Sciences President’s International Fellowship initiative(2017VEA0002)Research Equipment Program of Chinese Academy of Sciences(YJKYYQ20170018)
文摘基于Laudau-Devonshire的热动力学模型,计算了Eu Ti O3铁电薄膜材料的电热效应.结果显示在外加应力的调控下,电极化、电热系数以及绝热温差都会随之变化.外加垂直于表面的张应力加大,薄膜的相变温度升高,绝热温差增加,最大绝热温差所对应的工作温度向高温区移动.对于二维平面失配应变um-.的薄膜,当外加张应力σ33 GPa时,其最大电热系数为1.75×10-C/m2·K,电场变化200 MV/m时室温下绝热温差T的最大值可达到14 K以上,绝热温差T K的工作温区超过120 K,表明可以通过调控外部应力来获取室温时较大的绝热温差.此结果预示着铁电Eu Ti O3薄膜在室温固态制冷方面可能具有较好的应用前景.
