To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 m...To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 mol%)ceramics were successfully synthesized by traditional solid-state sintering method.The phase structure and microstructure of ceramics were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM)and piezoresponse force microscopyeramics(PFM).The electric properties of ceramics were researched through piezoelectric,dielectric and ferroelectric test instruments.The results show that all samples have pure perovskite structure and favorable electric properties.The optimal electric properties which especially include superior ferroelectric properties are gained when Y_(2)O_(3)content is 0.06 mol%(d_(33)=419 pC/N,k_(p)=52%,T_(c)=89.5℃,ε_(r)=26900,tanδ=2.86%,P_(r)=14.41μC/cm^(2),Ec=1.8 kV/cm).Moreover,the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies.The Curie-Weiss law further proves that all samples are typical relaxor ferroelectrics,and the relaxor degree of samples decreases with increase of Y_(2)O_(3)content.In conclusion,Y_(2)O_(3)plays a significant role in enhancing electric properties of BCTSZ ceramics.展开更多
With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recen...With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.展开更多
The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning elec...The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning electron microscope,electric parameter testing system and ferroelectric tester.It is found that the barium zirconate titanate based ceramics are single-phase perovskites as y increases up to 0.05 and their average grain size decreases with the increase of y.The permittivity maximumεr,max is suppressed from 8948 to 1611 at 1 kHz with increasing y,and the ferroelectric-paraelectric phase transition temperature Tm decreases from 93 to-89℃at 1 kHz as y increases.The composition-induced diffuse phase transition is enhanced with increasingy.The relaxor-like ferroelectric behavior with a strong frequency dispersion of Tm and permittivity at T<Tm accompanied by a strong diffuse phase transition is found for the system with high y value.The remnant polarization decreases with increasing y,while the coercive field decreases remarkably and then increases with the increase of y.展开更多
In the present work, the phase transitions and relaxor behavior of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT, x = 0.2―0.4) ferroelectric ceramics have been investigated by means of X-ray diffraction, di-electric spectros...In the present work, the phase transitions and relaxor behavior of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT, x = 0.2―0.4) ferroelectric ceramics have been investigated by means of X-ray diffraction, di-electric spectroscopy, the P-E hysteresis loop measurements and Raman scattering techniques. Structural analysis revealed that with the increase of PbTiO3 content, PMN-PT ceramics experienced a gradual phase transition process from rhombohedral to tetragonal. It is usually believed that such kinds of phase transitions resulted in the linear decrease of relaxation degree. Surprisingly, our analysis of the dielectric spectra revealed that the indicator of the degree of diffuseness γ reached the maximum value near morphotropic phase boundary (MPB) (x = 0.32), then decreased with the further increase of PbTiO3 content. The large dielectric relaxor feature near MPB may be attributed to the for-mation of ordered nanodomains, resulting from complex coexisting nanostructures. Further, the P-E hysteresis loop measurements and Raman analysis of the B-site cation order correlated well with the dielectric measurement results. It was found that the hysteresis loop squareness Rsq received the minimum value while the inverse of the value of full wide of half maximum (FWHM) of A1g mode reached the maximum value at MPB composition, which showed similar trends to γ.展开更多
多铁性材料同时具有多种铁性(铁电性、铁磁性或铁弹性)的有序,可实现电磁信号的相互控制,成为近年来研究热点。在具有成分无序的复杂体系中,长程铁性有序有可能被打破,材料将表现出弛豫特性。我们将至少存在一种铁性弛豫特性的多铁性材...多铁性材料同时具有多种铁性(铁电性、铁磁性或铁弹性)的有序,可实现电磁信号的相互控制,成为近年来研究热点。在具有成分无序的复杂体系中,长程铁性有序有可能被打破,材料将表现出弛豫特性。我们将至少存在一种铁性弛豫特性的多铁性材料称之为弛豫多铁性材料。这类多铁性材料的极化强度(或磁化强度)在外加电场(或外加磁场)作用下响应更加灵敏,其磁电耦合机制与长程有序的多铁性材料不同。本文结合国内外最新研究成果,首先介绍了和弛豫铁性有序相关的物理概念,重点阐述了多铁性材料在铁电和铁磁双弛豫态下的磁电耦合机制;然后,详细介绍了钙钛矿结构(包括Pb B_1B_2O_3基和Bi Fe O_3基材料)和非钙钛矿结构(包括层状Bi结构和非正常铁电体)弛豫多铁性材料的研究进展;最后,对该领域亟待解决的问题进行了展望。展开更多
RELAXOR ferroelectric ceramics with complex perovskite structure is considered as the first material chosen for multilayer capacitors (MLC) in technology and economy, because of their high permittivity, lower sinterin...RELAXOR ferroelectric ceramics with complex perovskite structure is considered as the first material chosen for multilayer capacitors (MLC) in technology and economy, because of their high permittivity, lower sintering temperature and lower capacitors changing rate with temperature (temperature coefficient) for diffuse phase transition (DPT). Thus, preparations and properties about the materials received more attention. There are many reports about their dielectric properties but there are few about their poled dielectric behavior. In the展开更多
Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses a...Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.展开更多
Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials b...Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials by doping with multiple elements,but the preparation method is complicated because a high maximum polarization(P_(max))is sacrificed,which affects the energy storage properties.In this work,we induced antiferroelectric-like relaxor behavior by replacing Bi^(3+)with the single rare-earth ion Pr^(3+)to obtain highly active polar nanoregions(PNRs)that increase the energy storage efficiency(ƞ).In addition,the 6s^(2)lone pair of electrons of Pr^(3+)can produce large ionic displacements similar to those of Bi^(3+).This could maintain the contribution of the A-site polarization to possess large P_(max).Moreover,the high energy gap(E_(g))and reliability increase the breakdown electric field(E_(b)).Consequently,the ultrahigh recoverable energy storage density(Wrec)of 11.01 J/cm^(3)at 552 kV/cm andηof 86.7%are achieved with(Bi_(0.5−x)Pr_(x)Na_(0.5))TiO_(3)component(BPNT-18),which is superior to many other multielement components.It also has fast charging and discharging speeds(t_(0.9)≈37 ns)and high power densities(P_(D)≈312 MW/cm^(3)).This research proposes a simple and effective approach in which a single element is used to obtain excellent energy storage performance in lead-free dielectric ceramics.展开更多
Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy s...Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy storage properties(ESP)of Bi_(0.5)Na_(0.5)TiO_(3) ceramics using CaTiO_(3) incorporation.The dielectric breakdown strength was effectively enhanced,and simultaneously the relaxor behavior was optimized to lower the remnant polarization,which is resulted from the decreased grains size with the introduction of Ca^(2+)ion.Remarkably,at a CaTiO_(3) doping level of 0.2,a 0.8Bi_(0.5)Na_(0.5)TiO_(3)-0.2CaTiO_(3)(0.8BNT-0.2CT)ceramic obtained both high energy storage density(Wtotal)of~1.38 J/cm^(3) together with excellent efficiency(h)of~91.3%.Furthermore,an ultrafast discharge response speed(t0:9)~94 ns was achieved in 0.8BNT-0.2CT ceramic,as well as tremendous current density(C_(D)~1520 A/cm2)and power density(P_(D)~115 MW/cm^(3)).This study not only revealed the superior ESP mechanism as regards Bi_(0.5)Na_(0.5)TiO_(3) based ceramics but also provided candidate materials in pulse power capacitor devices.展开更多
The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out.We examined the dielectric properties(including behavior in...The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out.We examined the dielectric properties(including behavior in electric fields)of two pyrochlore compounds:BZN(presumably a composition close to Bi_(1.5)Zn_(0.5)Nb_(1.5)O_(6.5))ceramics with chemical disorder in both A and B cation sublattices and Bi_(2)Ti_(2)O_(7)single crystal with fully chemical ordered structure.The fundamental differences between the dielectric properties of the BZN ceramics and Bi_(2)Ti_(2)O_(7)single crystal were shown.In particular,in the dielectric relaxation behavior(which cannot be described via Arrhenius law in the Bi_(2)Ti_(2)O_(7))or in the influence of the electric fields on the dielectric permittivity(split-ting of the field-cooled and zero-field-cooled behaviors was observed for Bi_(2)Ti_(2)O_(7)below estimated freezing temperature).The results of this study highlights the special role of Bi_(2)Ti_(2)O_(7)as a candidate material for studying aspects of geometric frustration related with pyrochlore structure in non-magnetic medium and specifies the future directions of research.展开更多
基金Project supported by the Guizhou Province Graduate Research Fund(YJSCXJH2020029)Specialized Funds from Industry and Information Technology Department of Guizhou Province(2016056)+1 种基金the National Natural Science Foundation of China(51602066)High-level Innovative Talents Plan of Guizhou Province((2015)4009)。
文摘To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 mol%)ceramics were successfully synthesized by traditional solid-state sintering method.The phase structure and microstructure of ceramics were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM)and piezoresponse force microscopyeramics(PFM).The electric properties of ceramics were researched through piezoelectric,dielectric and ferroelectric test instruments.The results show that all samples have pure perovskite structure and favorable electric properties.The optimal electric properties which especially include superior ferroelectric properties are gained when Y_(2)O_(3)content is 0.06 mol%(d_(33)=419 pC/N,k_(p)=52%,T_(c)=89.5℃,ε_(r)=26900,tanδ=2.86%,P_(r)=14.41μC/cm^(2),Ec=1.8 kV/cm).Moreover,the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies.The Curie-Weiss law further proves that all samples are typical relaxor ferroelectrics,and the relaxor degree of samples decreases with increase of Y_(2)O_(3)content.In conclusion,Y_(2)O_(3)plays a significant role in enhancing electric properties of BCTSZ ceramics.
基金supported by the National Natural Science Foundation of China(Grant No.52072150)the Young Elite Scientists Sponsorship Program of the Chinese Academy of Space Technology(CAST)and Open Foundation of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices(EFMD2021002Z).
文摘With the increasing demand of high-power and pulsed power electronic devices,environmental-friendly potassium sodium niobate((Na_(0.5)K_(0.5))NbO_(3),KNN)ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density(W_(rec)).Nevertheless,the dielectric loss also increases as the external electric field increases,which will generate much dissipated energy and raise the temperature of ceramic capacitors.Thus,an effective strategy is proposed to enhance the energy storage efficiency(η)via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na_(0.5)K_(0.5))-NbO_(3)-0.1Bi(Zn_(2/3)(Nb_(x)Ta_(1−x))1/3)O_(3) ceramics.On the one hand,the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short−range polar nanoregions(PNRs),resulting in the highη.On the other hand,the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the Eb.As a result,high Wrec of 3.29 J/cm^(3) and ultrahighηof 90.1%at the high external electric field of 310 kV/cm are achieved in x=0.5 sample.These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.
基金sponsored by the National Demonstration Center for Experimental Materials Science and Engineering Education (Jiangsu University of Science and Technology, China)the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions, China
文摘The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning electron microscope,electric parameter testing system and ferroelectric tester.It is found that the barium zirconate titanate based ceramics are single-phase perovskites as y increases up to 0.05 and their average grain size decreases with the increase of y.The permittivity maximumεr,max is suppressed from 8948 to 1611 at 1 kHz with increasing y,and the ferroelectric-paraelectric phase transition temperature Tm decreases from 93 to-89℃at 1 kHz as y increases.The composition-induced diffuse phase transition is enhanced with increasingy.The relaxor-like ferroelectric behavior with a strong frequency dispersion of Tm and permittivity at T<Tm accompanied by a strong diffuse phase transition is found for the system with high y value.The remnant polarization decreases with increasing y,while the coercive field decreases remarkably and then increases with the increase of y.
基金Supported by the National Natural Science Foundation of China (Grant No. 60601020)Project of New Star of Science and Technology of Beijing (Grant No. 2007A014)+1 种基金Natural Science Foundation of Beijing (Grant No. 4072006)Science and Technology Development Project of Beijing Education Committee (Grant No. KM200810005012)
文摘In the present work, the phase transitions and relaxor behavior of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT, x = 0.2―0.4) ferroelectric ceramics have been investigated by means of X-ray diffraction, di-electric spectroscopy, the P-E hysteresis loop measurements and Raman scattering techniques. Structural analysis revealed that with the increase of PbTiO3 content, PMN-PT ceramics experienced a gradual phase transition process from rhombohedral to tetragonal. It is usually believed that such kinds of phase transitions resulted in the linear decrease of relaxation degree. Surprisingly, our analysis of the dielectric spectra revealed that the indicator of the degree of diffuseness γ reached the maximum value near morphotropic phase boundary (MPB) (x = 0.32), then decreased with the further increase of PbTiO3 content. The large dielectric relaxor feature near MPB may be attributed to the for-mation of ordered nanodomains, resulting from complex coexisting nanostructures. Further, the P-E hysteresis loop measurements and Raman analysis of the B-site cation order correlated well with the dielectric measurement results. It was found that the hysteresis loop squareness Rsq received the minimum value while the inverse of the value of full wide of half maximum (FWHM) of A1g mode reached the maximum value at MPB composition, which showed similar trends to γ.
文摘多铁性材料同时具有多种铁性(铁电性、铁磁性或铁弹性)的有序,可实现电磁信号的相互控制,成为近年来研究热点。在具有成分无序的复杂体系中,长程铁性有序有可能被打破,材料将表现出弛豫特性。我们将至少存在一种铁性弛豫特性的多铁性材料称之为弛豫多铁性材料。这类多铁性材料的极化强度(或磁化强度)在外加电场(或外加磁场)作用下响应更加灵敏,其磁电耦合机制与长程有序的多铁性材料不同。本文结合国内外最新研究成果,首先介绍了和弛豫铁性有序相关的物理概念,重点阐述了多铁性材料在铁电和铁磁双弛豫态下的磁电耦合机制;然后,详细介绍了钙钛矿结构(包括Pb B_1B_2O_3基和Bi Fe O_3基材料)和非钙钛矿结构(包括层状Bi结构和非正常铁电体)弛豫多铁性材料的研究进展;最后,对该领域亟待解决的问题进行了展望。
文摘RELAXOR ferroelectric ceramics with complex perovskite structure is considered as the first material chosen for multilayer capacitors (MLC) in technology and economy, because of their high permittivity, lower sintering temperature and lower capacitors changing rate with temperature (temperature coefficient) for diffuse phase transition (DPT). Thus, preparations and properties about the materials received more attention. There are many reports about their dielectric properties but there are few about their poled dielectric behavior. In the
基金supported by the Natural Science Foundation of China(Grant No.51902246,12161141012,and 12174299)the China National Key R&D Program(Grant No.2021YFB3201800 and 2020YFC0122100)+5 种基金the Natural Science Fundamental Research Project of Shaanxi Province of China(No.2019JQ590)the Key R&D Program of Shaanxi Province of China(2020GY-271)the Fundamental Research Funds for the Central Universities(xzd012020059)the“111 Project”of China(B14040)the Natural Sciences&Engineering Research Council of Canada(NSERC,Discovery Grant No.RGPIN-2017-06915)Xijiang Innovation Team Introduction Program of Zhaoqing(Jiecheng).
文摘Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.
基金supported by the Key Deployment Projects of the Chinese Academy of Sciences(No.ZDRW-CN-2021-3-1-18)the National Natural Science Foundation of China(No.61475176)+1 种基金the Major Science and Technology Project of Yunnan Province(Nos.202302AB080023 and 202402AC080002)the Special Project for Provincial and Municipal Integration of Yunnan Province(No.202302AH360002).
文摘Bi_(0.5)Na_(0.5)TiO_(3)(BNT)has received much attention because of its excellent dielectric properties for pulsed power systems.Most of the work has focused on inducing the relaxation behavior of BNT-based materials by doping with multiple elements,but the preparation method is complicated because a high maximum polarization(P_(max))is sacrificed,which affects the energy storage properties.In this work,we induced antiferroelectric-like relaxor behavior by replacing Bi^(3+)with the single rare-earth ion Pr^(3+)to obtain highly active polar nanoregions(PNRs)that increase the energy storage efficiency(ƞ).In addition,the 6s^(2)lone pair of electrons of Pr^(3+)can produce large ionic displacements similar to those of Bi^(3+).This could maintain the contribution of the A-site polarization to possess large P_(max).Moreover,the high energy gap(E_(g))and reliability increase the breakdown electric field(E_(b)).Consequently,the ultrahigh recoverable energy storage density(Wrec)of 11.01 J/cm^(3)at 552 kV/cm andηof 86.7%are achieved with(Bi_(0.5−x)Pr_(x)Na_(0.5))TiO_(3)component(BPNT-18),which is superior to many other multielement components.It also has fast charging and discharging speeds(t_(0.9)≈37 ns)and high power densities(P_(D)≈312 MW/cm^(3)).This research proposes a simple and effective approach in which a single element is used to obtain excellent energy storage performance in lead-free dielectric ceramics.
基金This work was supported by the National Natural Science Foundation of China(Grant NO 51872177)The authors would also like to thank the Natural Science Basic Research Plan in the Shaanxi Province of China(Grant No.2022JQ-338,2021ZDLSF06-03,2021JM-201)+1 种基金Science and Technology Project of Xian,China(Grant No.2020KJRC0014)the Fundamental Research Funds for the Central Universities(Program No.GK202002014).
文摘Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy storage properties(ESP)of Bi_(0.5)Na_(0.5)TiO_(3) ceramics using CaTiO_(3) incorporation.The dielectric breakdown strength was effectively enhanced,and simultaneously the relaxor behavior was optimized to lower the remnant polarization,which is resulted from the decreased grains size with the introduction of Ca^(2+)ion.Remarkably,at a CaTiO_(3) doping level of 0.2,a 0.8Bi_(0.5)Na_(0.5)TiO_(3)-0.2CaTiO_(3)(0.8BNT-0.2CT)ceramic obtained both high energy storage density(Wtotal)of~1.38 J/cm^(3) together with excellent efficiency(h)of~91.3%.Furthermore,an ultrafast discharge response speed(t0:9)~94 ns was achieved in 0.8BNT-0.2CT ceramic,as well as tremendous current density(C_(D)~1520 A/cm2)and power density(P_(D)~115 MW/cm^(3)).This study not only revealed the superior ESP mechanism as regards Bi_(0.5)Na_(0.5)TiO_(3) based ceramics but also provided candidate materials in pulse power capacitor devices.
基金The authors are grateful to L.A.Shilkina for X-ray phase analysis of the BZN samples.The reported study was funded by Russian Science Foundation(RSF)-research projects no.20-72-00086(BZN ceramics preparation,dielectric mea-surements)At RTU MIREA,the work was supported by the Ministry of Science and Higher Education of Russia(project FSFZ 0706-2020-2022,Bi2Ti2O7 single crystal growth),the equipment of the Center for Collective Use of RTU MIREA was used.
文摘The comparative analysis of the dielectric properties of bismuth-containing pyrochlores with different manifestation of atomic order/disorder was carried out.We examined the dielectric properties(including behavior in electric fields)of two pyrochlore compounds:BZN(presumably a composition close to Bi_(1.5)Zn_(0.5)Nb_(1.5)O_(6.5))ceramics with chemical disorder in both A and B cation sublattices and Bi_(2)Ti_(2)O_(7)single crystal with fully chemical ordered structure.The fundamental differences between the dielectric properties of the BZN ceramics and Bi_(2)Ti_(2)O_(7)single crystal were shown.In particular,in the dielectric relaxation behavior(which cannot be described via Arrhenius law in the Bi_(2)Ti_(2)O_(7))or in the influence of the electric fields on the dielectric permittivity(split-ting of the field-cooled and zero-field-cooled behaviors was observed for Bi_(2)Ti_(2)O_(7)below estimated freezing temperature).The results of this study highlights the special role of Bi_(2)Ti_(2)O_(7)as a candidate material for studying aspects of geometric frustration related with pyrochlore structure in non-magnetic medium and specifies the future directions of research.
