The multi-layer ceramic capacitor (MLCC) alignment system aims at the inter-process automation between the first and the second plastic processes.As a result of testing performance verification of MLCC alignment syste...The multi-layer ceramic capacitor (MLCC) alignment system aims at the inter-process automation between the first and the second plastic processes.As a result of testing performance verification of MLCC alignment system,the average alignment rates are 95% for 3216 chip,88.5% for 2012 chip and 90.8% for 3818 chip.The MLCC alignment system can be accepted for practical use because the average manual alignment is just 80%.In other words,the developed MLCC alignment system has been upgraded to a great extent,compared with manual alignment.Based on the successfully developed MLCC alignment system,the optimal transfer conditions have been explored by using RSM.The simulations using ADAMS has been performed according to the cube model of CCD.By using MiniTAB,the model of response surface has been established based on the simulation results.The optimal conditions resulted from the response optimization tool of MiniTAB has been verified by being assigned to the prototype of MLCC alignment system.展开更多
To further study the effect of sputtered Au film as transition electrode layer on the electrical properties and interface microstructures of Na20-PbO-Nb2O5-SiO2 multilayer glass-ceramic capacitors, Au films pre-deposi...To further study the effect of sputtered Au film as transition electrode layer on the electrical properties and interface microstructures of Na20-PbO-Nb2O5-SiO2 multilayer glass-ceramic capacitors, Au films pre-deposited at different time were prepared by DC magnetron sputtering. Compared with the single paste electrode structure, samples with Au films pre-deposited from 6 to 18 min have the consistent perfor- mance to effectively improve the electrical properties of the capacitors, resulting in the doubled breakdown strength, an increase of equivalent capacitance by 22% and a decrease of leakage current by an order of magnitude. SEM observations indicate that the Au films with deposition time from 6 to 18 min would all help the formation of a dense electrode/dielectric interface and inhibit the diffusion of Ag. The results reveal that Au film pre-deposited for 6 min as inner electrode was sufficient to improve the interface microstructure and therefore to inhibit the Ag diffusion and enhance the overall performance of the multi-layer glass-ceramic capacitors.展开更多
The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional tec...The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional technology process and orthogonal design experiments. The major secondary influencing factors and the influencing tendency of various factor＇s levels for the dielectric properties of BST ceramics were obtained. The optimum formula for maximum dielectric constant （ε） and for minimum dielectric loss （tanδ） was obtained under the experimental conditions. The BST ceramics with optimum comprehensive properties was obtained by means of orthogonal design experiments, with the sintering temperature at 1200 ℃, the dielectric constant 5239, the dielectric loss 0.0097, withstand electric voltage over 6 MV·m^-1, capacitance temperature changing ence of various components on the providing the basis for preparation rate （△C/C） - 75.67%, and suited for Y5V character. The mechanism of the infludielectric properties of medium temperature sintering BST ceramics was studied, thus of multilayer capacitor ceramics and single-chip capacitor ceramics.展开更多
0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance v...0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance variation limit)at 1 kHZ.The distribution of internal electric field under breakdown voltage was simulated by finite element method(FEM),indicating that the electric field strength increased significantly at the terminal of internal electrode.These areas may become the headstream of breakdown for MLCC-1 due to the shape mutation.In order to improve the breakdown performance of MLCC-1,it was optimized by 12BA5N+2G green sheets(prepared by 12BA5N ceramic powder with 2 wt%B-Al-Si glass additive),then MLCC-2 was obtained which satisfied EIA X8R specification.Its BDS rose from 20 to29.4 kV·mm^(-1),and the electric field distribution of dielectric layer was also analyzed by FEM.Besides,it was also found that the grain size and the dielectric constants of"core"and"shell"parts for the 12BA5N+2G dielectric layer both contributed to the enhanced BDS of MLCC-2according to the simulation results from FEM.展开更多
The rapid development of high-power and pulsed-power techniques inspires extensive investigates on high-performance ceramic-based capacitors.However,the low recoverable energy density(Wrec)hampers their wider applicat...The rapid development of high-power and pulsed-power techniques inspires extensive investigates on high-performance ceramic-based capacitors.However,the low recoverable energy density(Wrec)hampers their wider applications.Herein,the non-stoichiometric Bi_(0.5)Na_(0.5)TiO_(3)-based ceramics were designed and studied.The proper introduction of oxygen vacancies facilitated activating defect dipole,giving rise to reduced remanent polarization.Consequently,the optimal composition exhibited an exceptional high Wrec of 8.3 J/cm^(3),a high efficiency of 85%,and excellent anti-fatigue and thermal reliability.This work provides an efficient approach to explore ceramic capacitors with high capacitive energy storage performances.展开更多
Four BT-based ceramic samples were prepared using a grain grading approach.The bigger-grained(~100 nm)and smaller-grained(~70 nm)BaTiO_(3)(BT)powders were mixed.The smaller-grained BT powder controlled the average gra...Four BT-based ceramic samples were prepared using a grain grading approach.The bigger-grained(~100 nm)and smaller-grained(~70 nm)BaTiO_(3)(BT)powders were mixed.The smaller-grained BT powder controlled the average grain size and guaranteed the reliability,while the bigger-grained powder enhanced the dielectric constant.Various percentages of bigger-grained BT powder were introduced to balance the average grain size and the dielectric constant.As the proportion of bigger grains increased,the dielectric constant(εr)improved significantly.The room-temperatureεr of 25%bigger-grain mixed BT(2623)was~50%higher than that of the sample with a similar average grain size without grain grading.The ceramic mixed with 15%bigger-grained BT showed comprehensive dielectric performance,which met the EIA X5R standard and provided a considerableεr of 1841 along with a low dielectric loss of 0.78%.Notably,the average grain size was 90 nm,which favors the applications in ultra-thin multilayer ceramic capacitors.展开更多
The effect of Sm 2O 3 dopant on the sintering characteristics and dielectric properties of barium zirconium titanate ceramics (BaZr x Ti 1- x O 3) was investigated. It is shown that trace amount of Sm ...The effect of Sm 2O 3 dopant on the sintering characteristics and dielectric properties of barium zirconium titanate ceramics (BaZr x Ti 1- x O 3) was investigated. It is shown that trace amount of Sm 2O 3 can greatly affect the grain growth and densification of barium zirconium titanate ceramics during sintering. At the same time, the dielectric peak at high temperature shifts to lower temperature and that at low temperature shifts to higher temperature. The two dielectric peaks overlap with each other when the Sm 2O 3 dopant content varies from 0 25% to 1%, and the maximum relative dielectric constant is greatly enhanced. These effects may be attributed to the substitution actions of the rare earth element in perovskite lattice. At the doping content of 0 75%, the dielectric constant maximum of 23570 can be obtained. By adopting some proper additives, an excellent Y5V dielective material is obtained, and the room temperature properties are as follows: relative dielectric constant ε RT ≥23,000, dielectric loss tgδ≤0 0075 and the breakdown strength under alternating field E b≥5 kV·mm -1 .展开更多
The effect of SiO2 doping on the sintering behavior, microstructure, and dielectric properties of BaTiO3-based ceramics has been investigated. Silica was added to the BaTiO3-based powder prepared by the solid state me...The effect of SiO2 doping on the sintering behavior, microstructure, and dielectric properties of BaTiO3-based ceramics has been investigated. Silica was added to the BaTiO3-based powder prepared by the solid state method with 0.075mol%, 0.15mol%, and 0.3mol%, respectively. The SiO2-doped BaTiO3-based ceramic with high density and uniform grain size were obtained, which were sintered in reducing atmosphere. A scanning electron microscope, X-ray diffraction, and LCR meter were used to determine the microstructure as well as the dielectric properties. SiO2 can form a liquid phase belonging to the ternary system of BaO-TiO2-SiO2, leading to the formation of BaTiO3 ceramics with high density at a lower sintering temperature. The SiO2-doped BaTiO3-based ceramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h. The dielectric constants of the sample with 0.15mol% SiO2 addition sintered at 1220℃ is about 9000. Doping with a small amount of silica can improve the sintering and dielectric properties of BaTiO3-based ceramics.展开更多
The effect of Yb2O3 doping amount on the dielectric properties of (Ba, Sr)TiO3 (BST) series capacitor ceramics prepared using solid state reaction method were studied. With the increasing of Yb2O3 doping amount, the d...The effect of Yb2O3 doping amount on the dielectric properties of (Ba, Sr)TiO3 (BST) series capacitor ceramics prepared using solid state reaction method were studied. With the increasing of Yb2O3 doping amount, the dielectric constant(ε) of materials increased, the dielectric loss(tanδ) of materials decreased to minimum when w(Yb2O3) was 0.9%. The BST ceramics with high ε(10000), low tanδ(0.0213) and high DC breakdown voltage(7.2 kV·mm-1) were obtained. The influence of Yb2O3 doping amount on the structure of BST ceramics was studied by means of X-ray diffraction(XRD) and scanning electron microscope. The influencing mechanism of Yb2O3 on the dielectric properties of BST ceramics was studied. The results showed that Yb2O3 doping influenced the properties and structure of BST ceramics by means of forming defect solid solution, but did not influence crystal grain size,the crystal phase was single perovskite structure, did not influence XRD data of BST and did not improve capacitance temperature property greatly, but increase dielectric constant greatly. These results provided the basis for Yb2O3-doped BST series capacitor ceramics.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
Multilayer ceramic capacitors(MLCCs)play a crucial role in pulsed power applications because of their rapid charge/discharge capabilities.However,the combination of high energy density and high efficiency is the main ...Multilayer ceramic capacitors(MLCCs)play a crucial role in pulsed power applications because of their rapid charge/discharge capabilities.However,the combination of high energy density and high efficiency is the main challenge in practical applications.This study presents barium titanate-based(BaTiO_(3)-)lead-free relaxor ferroelectric(RFE)MLCCs formulated with 0.84BaTiO_(3)–0.16Bi(Mg_(0.2)Ni_(0.2)Zn_(0.2)Zr_(0.2)Nb_(0.2))O_(3)(0.84BT–0.16BMNZZN)and platinum inner electrodes via a tape-casting method.The introduction of the high-entropy component BMNZZN effectively enhances the relaxation behavior and local nanodomains while promoting grain refinement,resulting in a comprehensive improvement in insulation performance and energy storage performance.As a result,MLCCs exhibit excellent recoverable energy density(W_(rec)=15.7 J∙cm^(−3))and ultrahigh efficiency(η)of 96.4%(@1614 kV∙cm−1),simultaneously showing good temperature stability over a range of−120‒100℃(W_(rec)≈8.9 J∙cm^(−3)with a variation of less than±4.85%,@1078 kV∙cm−1)and excellent fatigue resistance(W_(rec)≈9.2 J∙cm^(−3)with a variation of less than±0.82%over 107 cycles,andηgreater than 95%,@1078 kV∙cm−1).These findings indicate that BT–BMNZZN RFE MLCCs offer a viable solution for high-power energy storage capacitors.展开更多
SrTiO 3 capacitor varistor multifunction ceramics is fabricated by a single sintering process. The research is carried out, mainly aimed at the influence of the doped Ag + on multifunction characteristics in SrTiO 3 c...SrTiO 3 capacitor varistor multifunction ceramics is fabricated by a single sintering process. The research is carried out, mainly aimed at the influence of the doped Ag + on multifunction characteristics in SrTiO 3 ceramics and its mechanism. The results show that the density of grain boundary acceptor state increases effectively due to the fact that Sr 2+ on grain surface is substituted by doped Ag distributing at grain boundary in form of Ag + during the course of oxidizing annealing, which is proposed to be the fundamental reason for understanding the significant difference of both the dielectric properties and varistor properties in SrTiO 3 ceramics samples with various Ag + contents.展开更多
After people or vehicles press, piezoelectric ceramics can send a weak and unstable alternating current. According to this characteristic, we made feet pressing energy collection and utilization device based on piezoe...After people or vehicles press, piezoelectric ceramics can send a weak and unstable alternating current. According to this characteristic, we made feet pressing energy collection and utilization device based on piezoelectric ceramics. The two parts of this device includes energy storage and utilization. In terms of storage, the energy collection module, can deposit AC sent by piezoelectric ceramics in the super capacitor after rectification. In terms of utilization of energy, the device achieve a variety of usage： through the USB interface, it can supply power for different equipments, replace the mobile station of train stations and realize the function of saving the electricity as the night corridor induction lamp, combined with vibration module design and programmable timer. The whole structure is supported by an acrylic plate, which saves cost and have good durability. This device implements the storage and usage of idle feet pressing energy. In conclusion, it is helpful to provide a new idea for people＇ s low carbon lives and has a quite broad application prospect.展开更多
电子工业发展使多层陶瓷电容器的需求大增,为降低成本,适用于贱金属电极的介质陶瓷成为研究热点。选择MnO_(2)掺杂0.95Ba Ti O3–0.05Bi Co O3陶瓷,经调整掺杂比例,其抗还原与介电性能大幅提升。结果表明:还原气氛下Mn离子变价使晶胞体...电子工业发展使多层陶瓷电容器的需求大增,为降低成本,适用于贱金属电极的介质陶瓷成为研究热点。选择MnO_(2)掺杂0.95Ba Ti O3–0.05Bi Co O3陶瓷,经调整掺杂比例,其抗还原与介电性能大幅提升。结果表明:还原气氛下Mn离子变价使晶胞体积膨胀,形成不均匀结构使Curie峰分裂并展宽,介温稳定性提高,x=0.5时性能最佳,ε(25℃)=2354,tanδ=0.0075,稳定性符合X8R。同时,元素变价的过程有助于降低电子浓度,电阻率提高至1.84×10~(13)Ω·cm,最大耐压达到210 k V/cm。热激励退极化漏电流测试表明Co、Mn结合氧空位形成缺陷偶极,进一步增强抗还原性能。展开更多
基金supported by the Second Stage of Brain Korea 21 Projectssupported (in part) by the Solomon Mechanics Inc
文摘The multi-layer ceramic capacitor (MLCC) alignment system aims at the inter-process automation between the first and the second plastic processes.As a result of testing performance verification of MLCC alignment system,the average alignment rates are 95% for 3216 chip,88.5% for 2012 chip and 90.8% for 3818 chip.The MLCC alignment system can be accepted for practical use because the average manual alignment is just 80%.In other words,the developed MLCC alignment system has been upgraded to a great extent,compared with manual alignment.Based on the successfully developed MLCC alignment system,the optimal transfer conditions have been explored by using RSM.The simulations using ADAMS has been performed according to the cube model of CCD.By using MiniTAB,the model of response surface has been established based on the simulation results.The optimal conditions resulted from the response optimization tool of MiniTAB has been verified by being assigned to the prototype of MLCC alignment system.
基金financially supported by the National High Technical Research and Development Programme of China (No.2008AA03A236)
文摘To further study the effect of sputtered Au film as transition electrode layer on the electrical properties and interface microstructures of Na20-PbO-Nb2O5-SiO2 multilayer glass-ceramic capacitors, Au films pre-deposited at different time were prepared by DC magnetron sputtering. Compared with the single paste electrode structure, samples with Au films pre-deposited from 6 to 18 min have the consistent perfor- mance to effectively improve the electrical properties of the capacitors, resulting in the doubled breakdown strength, an increase of equivalent capacitance by 22% and a decrease of leakage current by an order of magnitude. SEM observations indicate that the Au films with deposition time from 6 to 18 min would all help the formation of a dense electrode/dielectric interface and inhibit the diffusion of Ag. The results reveal that Au film pre-deposited for 6 min as inner electrode was sufficient to improve the interface microstructure and therefore to inhibit the Ag diffusion and enhance the overall performance of the multi-layer glass-ceramic capacitors.
文摘The influence of the composition （Yb2O3, MgO, CeO2, Li2CO3） on the dielectric properties of medium temperature sintering （Ba, Sr）TiO3 （BST） series capacitor ceramics was investigated by means of conventional technology process and orthogonal design experiments. The major secondary influencing factors and the influencing tendency of various factor＇s levels for the dielectric properties of BST ceramics were obtained. The optimum formula for maximum dielectric constant （ε） and for minimum dielectric loss （tanδ） was obtained under the experimental conditions. The BST ceramics with optimum comprehensive properties was obtained by means of orthogonal design experiments, with the sintering temperature at 1200 ℃, the dielectric constant 5239, the dielectric loss 0.0097, withstand electric voltage over 6 MV·m^-1, capacitance temperature changing ence of various components on the providing the basis for preparation rate （△C/C） - 75.67%, and suited for Y5V character. The mechanism of the infludielectric properties of medium temperature sintering BST ceramics was studied, thus of multilayer capacitor ceramics and single-chip capacitor ceramics.
基金financially supported by Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(No.XHT2020-011)the Major Program of the Natural Science Foundation of China(No.51790490)+1 种基金Sanya Science and Education Innovation Park of Wuhan University of Technology(No.2020KF0017)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110060)。
文摘0.5 wt%Nb_(2)O_(5)doped 0.12BiAlO_(3)-0.88BaTiO_(3)(12BA5N)multilayer ceramic capacitor(MLCC-1)was prepared,which satisfied EIA X7R specification(where X is the minimum temperature,R is the percentage of capacitance variation limit)at 1 kHZ.The distribution of internal electric field under breakdown voltage was simulated by finite element method(FEM),indicating that the electric field strength increased significantly at the terminal of internal electrode.These areas may become the headstream of breakdown for MLCC-1 due to the shape mutation.In order to improve the breakdown performance of MLCC-1,it was optimized by 12BA5N+2G green sheets(prepared by 12BA5N ceramic powder with 2 wt%B-Al-Si glass additive),then MLCC-2 was obtained which satisfied EIA X8R specification.Its BDS rose from 20 to29.4 kV·mm^(-1),and the electric field distribution of dielectric layer was also analyzed by FEM.Besides,it was also found that the grain size and the dielectric constants of"core"and"shell"parts for the 12BA5N+2G dielectric layer both contributed to the enhanced BDS of MLCC-2according to the simulation results from FEM.
基金supported by the National Natural Science Foundation of China(Nos.12004181,52073144)Natural Science Foundation of Jiangsu Province(Nos.BK20200473,BK20201301)the Fundamental Research Funds for the Central Universities(No.30922010309)。
文摘The rapid development of high-power and pulsed-power techniques inspires extensive investigates on high-performance ceramic-based capacitors.However,the low recoverable energy density(Wrec)hampers their wider applications.Herein,the non-stoichiometric Bi_(0.5)Na_(0.5)TiO_(3)-based ceramics were designed and studied.The proper introduction of oxygen vacancies facilitated activating defect dipole,giving rise to reduced remanent polarization.Consequently,the optimal composition exhibited an exceptional high Wrec of 8.3 J/cm^(3),a high efficiency of 85%,and excellent anti-fatigue and thermal reliability.This work provides an efficient approach to explore ceramic capacitors with high capacitive energy storage performances.
基金supported by Ministry of Science and Technology of China through The Key Area Research Plan of Guangdong(Grant No.2019B010937001)High-end MLCC Key Project supported by Guangdong Fenghua Advanced Technology Holding Co.,Ltd.(No.20212001429)+1 种基金the National Key Research and Development Program of China(No.2017YFB0406302)the National Natural Science Foundation of China(No.52032005).
文摘Four BT-based ceramic samples were prepared using a grain grading approach.The bigger-grained(~100 nm)and smaller-grained(~70 nm)BaTiO_(3)(BT)powders were mixed.The smaller-grained BT powder controlled the average grain size and guaranteed the reliability,while the bigger-grained powder enhanced the dielectric constant.Various percentages of bigger-grained BT powder were introduced to balance the average grain size and the dielectric constant.As the proportion of bigger grains increased,the dielectric constant(εr)improved significantly.The room-temperatureεr of 25%bigger-grain mixed BT(2623)was~50%higher than that of the sample with a similar average grain size without grain grading.The ceramic mixed with 15%bigger-grained BT showed comprehensive dielectric performance,which met the EIA X5R standard and provided a considerableεr of 1841 along with a low dielectric loss of 0.78%.Notably,the average grain size was 90 nm,which favors the applications in ultra-thin multilayer ceramic capacitors.
文摘The effect of Sm 2O 3 dopant on the sintering characteristics and dielectric properties of barium zirconium titanate ceramics (BaZr x Ti 1- x O 3) was investigated. It is shown that trace amount of Sm 2O 3 can greatly affect the grain growth and densification of barium zirconium titanate ceramics during sintering. At the same time, the dielectric peak at high temperature shifts to lower temperature and that at low temperature shifts to higher temperature. The two dielectric peaks overlap with each other when the Sm 2O 3 dopant content varies from 0 25% to 1%, and the maximum relative dielectric constant is greatly enhanced. These effects may be attributed to the substitution actions of the rare earth element in perovskite lattice. At the doping content of 0 75%, the dielectric constant maximum of 23570 can be obtained. By adopting some proper additives, an excellent Y5V dielective material is obtained, and the room temperature properties are as follows: relative dielectric constant ε RT ≥23,000, dielectric loss tgδ≤0 0075 and the breakdown strength under alternating field E b≥5 kV·mm -1 .
基金supported by the Found No.NSC96-2218-E-020-004-005
文摘The effect of SiO2 doping on the sintering behavior, microstructure, and dielectric properties of BaTiO3-based ceramics has been investigated. Silica was added to the BaTiO3-based powder prepared by the solid state method with 0.075mol%, 0.15mol%, and 0.3mol%, respectively. The SiO2-doped BaTiO3-based ceramic with high density and uniform grain size were obtained, which were sintered in reducing atmosphere. A scanning electron microscope, X-ray diffraction, and LCR meter were used to determine the microstructure as well as the dielectric properties. SiO2 can form a liquid phase belonging to the ternary system of BaO-TiO2-SiO2, leading to the formation of BaTiO3 ceramics with high density at a lower sintering temperature. The SiO2-doped BaTiO3-based ceramics can be sintered to a theoretical density higher than 95% at 1220℃ with a soaking time of 2 h. The dielectric constants of the sample with 0.15mol% SiO2 addition sintered at 1220℃ is about 9000. Doping with a small amount of silica can improve the sintering and dielectric properties of BaTiO3-based ceramics.
文摘The effect of Yb2O3 doping amount on the dielectric properties of (Ba, Sr)TiO3 (BST) series capacitor ceramics prepared using solid state reaction method were studied. With the increasing of Yb2O3 doping amount, the dielectric constant(ε) of materials increased, the dielectric loss(tanδ) of materials decreased to minimum when w(Yb2O3) was 0.9%. The BST ceramics with high ε(10000), low tanδ(0.0213) and high DC breakdown voltage(7.2 kV·mm-1) were obtained. The influence of Yb2O3 doping amount on the structure of BST ceramics was studied by means of X-ray diffraction(XRD) and scanning electron microscope. The influencing mechanism of Yb2O3 on the dielectric properties of BST ceramics was studied. The results showed that Yb2O3 doping influenced the properties and structure of BST ceramics by means of forming defect solid solution, but did not influence crystal grain size,the crystal phase was single perovskite structure, did not influence XRD data of BST and did not improve capacitance temperature property greatly, but increase dielectric constant greatly. These results provided the basis for Yb2O3-doped BST series capacitor ceramics.
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.
基金funding from the Natural Science Foundation of Shanghai(Grant No.21ZR1473100)the National Natural Science Foundation of China(Grant Nos.U2002217,51831010,and 5227130).
文摘Multilayer ceramic capacitors(MLCCs)play a crucial role in pulsed power applications because of their rapid charge/discharge capabilities.However,the combination of high energy density and high efficiency is the main challenge in practical applications.This study presents barium titanate-based(BaTiO_(3)-)lead-free relaxor ferroelectric(RFE)MLCCs formulated with 0.84BaTiO_(3)–0.16Bi(Mg_(0.2)Ni_(0.2)Zn_(0.2)Zr_(0.2)Nb_(0.2))O_(3)(0.84BT–0.16BMNZZN)and platinum inner electrodes via a tape-casting method.The introduction of the high-entropy component BMNZZN effectively enhances the relaxation behavior and local nanodomains while promoting grain refinement,resulting in a comprehensive improvement in insulation performance and energy storage performance.As a result,MLCCs exhibit excellent recoverable energy density(W_(rec)=15.7 J∙cm^(−3))and ultrahigh efficiency(η)of 96.4%(@1614 kV∙cm−1),simultaneously showing good temperature stability over a range of−120‒100℃(W_(rec)≈8.9 J∙cm^(−3)with a variation of less than±4.85%,@1078 kV∙cm−1)and excellent fatigue resistance(W_(rec)≈9.2 J∙cm^(−3)with a variation of less than±0.82%over 107 cycles,andηgreater than 95%,@1078 kV∙cm−1).These findings indicate that BT–BMNZZN RFE MLCCs offer a viable solution for high-power energy storage capacitors.
文摘SrTiO 3 capacitor varistor multifunction ceramics is fabricated by a single sintering process. The research is carried out, mainly aimed at the influence of the doped Ag + on multifunction characteristics in SrTiO 3 ceramics and its mechanism. The results show that the density of grain boundary acceptor state increases effectively due to the fact that Sr 2+ on grain surface is substituted by doped Ag distributing at grain boundary in form of Ag + during the course of oxidizing annealing, which is proposed to be the fundamental reason for understanding the significant difference of both the dielectric properties and varistor properties in SrTiO 3 ceramics samples with various Ag + contents.
文摘After people or vehicles press, piezoelectric ceramics can send a weak and unstable alternating current. According to this characteristic, we made feet pressing energy collection and utilization device based on piezoelectric ceramics. The two parts of this device includes energy storage and utilization. In terms of storage, the energy collection module, can deposit AC sent by piezoelectric ceramics in the super capacitor after rectification. In terms of utilization of energy, the device achieve a variety of usage： through the USB interface, it can supply power for different equipments, replace the mobile station of train stations and realize the function of saving the electricity as the night corridor induction lamp, combined with vibration module design and programmable timer. The whole structure is supported by an acrylic plate, which saves cost and have good durability. This device implements the storage and usage of idle feet pressing energy. In conclusion, it is helpful to provide a new idea for people＇ s low carbon lives and has a quite broad application prospect.
文摘电子工业发展使多层陶瓷电容器的需求大增,为降低成本,适用于贱金属电极的介质陶瓷成为研究热点。选择MnO_(2)掺杂0.95Ba Ti O3–0.05Bi Co O3陶瓷,经调整掺杂比例,其抗还原与介电性能大幅提升。结果表明:还原气氛下Mn离子变价使晶胞体积膨胀,形成不均匀结构使Curie峰分裂并展宽,介温稳定性提高,x=0.5时性能最佳,ε(25℃)=2354,tanδ=0.0075,稳定性符合X8R。同时,元素变价的过程有助于降低电子浓度,电阻率提高至1.84×10~(13)Ω·cm,最大耐压达到210 k V/cm。热激励退极化漏电流测试表明Co、Mn结合氧空位形成缺陷偶极,进一步增强抗还原性能。
