Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and vali...Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H;O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.展开更多
The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain si...The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.展开更多
（Ba（0.6） Sr（0.4））（0.85） Bi（0.1） TiO3 ceramics doped with x wt%CaZrO3（x= 0-10） were synthesized by solid-state reaction method. The effects of CaZrO3 amount on the dielectric properties and structure of（Ba...（Ba（0.6） Sr（0.4））（0.85） Bi（0.1） TiO3 ceramics doped with x wt%CaZrO3（x= 0-10） were synthesized by solid-state reaction method. The effects of CaZrO3 amount on the dielectric properties and structure of（Ba（0.6）Sr（0.4））（0.85） Bi（0.1） TiO3 ceramics were investigated. X-ray diffraction results indicated a pure cubic perovskite structure for all samples and that the lattice parameter increased till x=5 and then slightly decreased. A homogenous microstructure was observed with the addition of CaZrO3. Dielectric measurements revealed a relaxor-like characteristic for all samples and that the diffusivity γ reached the maximum value of 1.78 at x=5. With the addition of CaZrO3, the dielectric constant dependence on electric field was weakened, insulation resistivity enhanced and dielectric breakdown strength improved obviously and reached 19.9 k V/mm at x=7.5. In virtue of low dielectric loss（tan d〈0.001 5）, moderate dielectric constant（er 〉1 500） and high breakdown strength（Eb 〉17.5 k V/mm）, the CaZrO3 doped（Ba（0.6）Sr（0.4））0.85 Bi（0.1） TiO3 ceramic is a potential candidate material for high power electric applications.展开更多
In this paper, the effects of annealing time on the dielectric properties of the Spark Plasma Sintered (SPS) BaMn3Ti4O14.25 pellets were detail studied by the crystal structure analysis, micro structural observation a...In this paper, the effects of annealing time on the dielectric properties of the Spark Plasma Sintered (SPS) BaMn3Ti4O14.25 pellets were detail studied by the crystal structure analysis, micro structural observation and electrical properties research. The results showed that long annealing time was beneficial to the recovery of crystal structure damage caused by SPS, the formation of a reoxidation layer at the surface of grains and decreasing of the electrically insulating phase. All of these resulted in an increase in dielectric constant and loss, and a reduction in breakdown voltage.展开更多
A novel partial silicon-on-insulator （PSOI） high voltage device with a low-k （relative permittivity） dielectric buried layer （LK PSOI） and its breakdown mechanism are presented and investigated by MEDICI. At a l...A novel partial silicon-on-insulator （PSOI） high voltage device with a low-k （relative permittivity） dielectric buried layer （LK PSOI） and its breakdown mechanism are presented and investigated by MEDICI. At a low k value the electric field strength in the dielectric buried layer （EI） is enhanced and a Si window makes the substrate share the vertical drop, resulting in a high vertical breakdown voltage; in the lateral direction, a high electric field peak is introduced at the Si window, which modulates the electric field distribution in the SOI layer; consequently, a high breakdown voltage （BV） is obtained. The values of EI and BV of LK PSOI with ki = 2 on a 2μm thick SOI layer over 1μm thick buried layer are enhanced by 74% and 19%, respectively, compared with those of the conventional PSOI. Furthermore, the Si window also alleviates the self-heating effect.展开更多
Elastomers are widely used in electronics and electrical devices,either as insulators or transducers.The insulation and actuation performance of elastomers are highly suscepti-ble to their dielectric strength.Among th...Elastomers are widely used in electronics and electrical devices,either as insulators or transducers.The insulation and actuation performance of elastomers are highly suscepti-ble to their dielectric strength.Among the factors that influ-encethedielectricstrength ofelastomers,material viscoelasticity is an important factor that needs further inves-tigation.Since the material viscoelasticity is often character-ized by rate-dependent behaviors,we present two different sample configurations to experimentally examine the electrical and mechanical rate dependence of the dielectric strength of VHB 4905 elastomers.At pre-stretch ratio of 4,the improve-ment of the dielectric strength is about 30%from voltage ramp of 50 V/s to 800 V/s.Particularly,with an in-house biaxial test platform,the effect of the stretching rate on the dielectric strength is examined for the first time.The improvement of the dielectric strength is about 35%from stretching rate of 0.1 mm/s to 5 mm/s.Moreover,a dielectric strength predictor based on configurational stress is adopted to describe the experimental data.According to the predictor,the loading rate affects the dielectric strength of the elastomer mainly by influencing the evolution of the inelastic deformation.展开更多
Next generation power system needs dielectrics with increased dielectric energy density.However,the low energy density of dielectrics limits their development.Here,an asymmetric trilayered nanocomposite,with a transit...Next generation power system needs dielectrics with increased dielectric energy density.However,the low energy density of dielectrics limits their development.Here,an asymmetric trilayered nanocomposite,with a transition layer(TL),an insulation layer(IL),and a polarization layer(PL),is designed based on poly(vinylidene fluoride)-polymethyl methacrylate(PVDF-PMMA)matrix using KNbO_(3)(KN)and TiO_(2)(TO)as the nanofillers.The morphology and defect control of the two-dimensional nano KN and nano TO fillers are realized via a hydrothermal method to increase the composite breakdown strength(E_(b))and the composite energy density(U_(e)).The asymmetric trilayered structure leads to a gradient electric field distribution,and the KN and TO nanosheets block charges transfer along z direction.As a result,the development path of the electrical trees is greatly curved,and E_(b) is effectively improved.And the Ue value of the nanocomposites reaches 17.79 J·cm^(-3) at 523 MV·m^(-1).On the basis,the composite Ue is further improved by defect control in TO nanosheets.The nanocomposite KN/TO/PVDF-PMMA containing TO with less oxygen vacancy concentration(calcined at oxygen atmosphere)acquires a high Ue of 21.61 J·cm^(-3) at 548 MV·m^(-1).This study provides an idea for improving the energy storage performance by combining the design of the composite dielectric structure and the control of nanofillers’defect and morphology.展开更多
聚合物纳米复合介质的击穿强度与纳米填充颗粒的质量分数、粒径和表面处理密切相关。以不同表面处理的纳米SiO2颗粒为填料，制备了不同填充质量分数、粒径的纳米SiO2／低密度聚乙烯（low density polyethylene,LDPE）复合介质，测试了...聚合物纳米复合介质的击穿强度与纳米填充颗粒的质量分数、粒径和表面处理密切相关。以不同表面处理的纳米SiO2颗粒为填料，制备了不同填充质量分数、粒径的纳米SiO2／低密度聚乙烯（low density polyethylene,LDPE）复合介质，测试了其在交流、直流正极性和直流负极性3种不同类型电场下的击穿场强。结果表明：在所研究范围内，填充纳米SiO2颗粒可以提高低密度聚乙烯的击穿场强，并且随着填充质量分数的增加，复合介质的击穿场强有升高的趋势。纳米颗粒填充质量分数相同时，在12～16am粒径下，复合介质的击穿场强有随纳米SiO2粒径的升高而降低的趋势；在7nm小粒径下，可能由于纳米颗粒容易团聚，导致击穿场强较粒径大时要低。另外，纳米SiO2颗粒表面经疏水性处理后，能够有效提高复合介质的击穿场强。展开更多
The exploration of high-energy-density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applicati...The exploration of high-energy-density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applications.The energy density of a capacitor is strongly dependent on dielectric constant and breakdown strength of a dielectric material.Here,we demonstrate a class of solution-processable polymer nanocomposites exhibiting a concurrent improvement in dielectric constant and breakdown strength,which typically show a negative correlation in conventional dielectric materials,along with a reduction in dielectric loss.The excellent performance is enabled by the elegant combination of nanostructured barium titanate and boron nitride fillers with complementary functionalities.The ternary polymer nanocomposite with the optimized filler compositions delivers a discharged energy density of 2.92 J cm^−3 and a Weibull breakdown strength of 547 MV m^−1 at 150℃,which are 83%and 25%,respectively,greater than those of the pristine polymer.The conduction behaviors including interfacial barrier and carrier transport process have been investigated to rationalize the energy storage performance of ternary polymer nanocomposite.This contribution provides a new design paradigm for scalable high-temperature polymer film capacitors.展开更多
基金supported by the National Key Basic Research Program of China(973 Program)2015CB251002National Natural Science Foundation of China under Grant 51521065,51577145+1 种基金the Fundamental Research Funds for the Central UniversitiesShaanxi Province Natural Science Foundation 2013JM-7010
文摘Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H;O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.
文摘The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.
基金Funded by the National Natural Science Foundation of China(No.51302093)the Fundamental Research Funds for the Central Universities of China(Nos.2014TS046,2015MS017)
文摘（Ba（0.6） Sr（0.4））（0.85） Bi（0.1） TiO3 ceramics doped with x wt%CaZrO3（x= 0-10） were synthesized by solid-state reaction method. The effects of CaZrO3 amount on the dielectric properties and structure of（Ba（0.6）Sr（0.4））（0.85） Bi（0.1） TiO3 ceramics were investigated. X-ray diffraction results indicated a pure cubic perovskite structure for all samples and that the lattice parameter increased till x=5 and then slightly decreased. A homogenous microstructure was observed with the addition of CaZrO3. Dielectric measurements revealed a relaxor-like characteristic for all samples and that the diffusivity γ reached the maximum value of 1.78 at x=5. With the addition of CaZrO3, the dielectric constant dependence on electric field was weakened, insulation resistivity enhanced and dielectric breakdown strength improved obviously and reached 19.9 k V/mm at x=7.5. In virtue of low dielectric loss（tan d〈0.001 5）, moderate dielectric constant（er 〉1 500） and high breakdown strength（Eb 〉17.5 k V/mm）, the CaZrO3 doped（Ba（0.6）Sr（0.4））0.85 Bi（0.1） TiO3 ceramic is a potential candidate material for high power electric applications.
文摘In this paper, the effects of annealing time on the dielectric properties of the Spark Plasma Sintered (SPS) BaMn3Ti4O14.25 pellets were detail studied by the crystal structure analysis, micro structural observation and electrical properties research. The results showed that long annealing time was beneficial to the recovery of crystal structure damage caused by SPS, the formation of a reoxidation layer at the surface of grains and decreasing of the electrically insulating phase. All of these resulted in an increase in dielectric constant and loss, and a reduction in breakdown voltage.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60806025 and 60976060)the National Laboratory of Analog Integrated Circuit (Grant No. 9140C0903070904)the Youth Teacher Foundation of the University of Electronic Science and Technology of China (Grant No. jx0721)
文摘A novel partial silicon-on-insulator （PSOI） high voltage device with a low-k （relative permittivity） dielectric buried layer （LK PSOI） and its breakdown mechanism are presented and investigated by MEDICI. At a low k value the electric field strength in the dielectric buried layer （EI） is enhanced and a Si window makes the substrate share the vertical drop, resulting in a high vertical breakdown voltage; in the lateral direction, a high electric field peak is introduced at the Si window, which modulates the electric field distribution in the SOI layer; consequently, a high breakdown voltage （BV） is obtained. The values of EI and BV of LK PSOI with ki = 2 on a 2μm thick SOI layer over 1μm thick buried layer are enhanced by 74% and 19%, respectively, compared with those of the conventional PSOI. Furthermore, the Si window also alleviates the self-heating effect.
基金supported by the National Natural Science Foundation of China(Project No.12102108)Guangdong Basic and Applied Basic Research Foundation(Project No.2020A1515111027)+1 种基金Shenzhen Science and Technology Program(Project No.JCYJ20210324120212034)Talent Recruitment Project of Guangdong(Project No.2021QN02G677).
文摘Elastomers are widely used in electronics and electrical devices,either as insulators or transducers.The insulation and actuation performance of elastomers are highly suscepti-ble to their dielectric strength.Among the factors that influ-encethedielectricstrength ofelastomers,material viscoelasticity is an important factor that needs further inves-tigation.Since the material viscoelasticity is often character-ized by rate-dependent behaviors,we present two different sample configurations to experimentally examine the electrical and mechanical rate dependence of the dielectric strength of VHB 4905 elastomers.At pre-stretch ratio of 4,the improve-ment of the dielectric strength is about 30%from voltage ramp of 50 V/s to 800 V/s.Particularly,with an in-house biaxial test platform,the effect of the stretching rate on the dielectric strength is examined for the first time.The improvement of the dielectric strength is about 35%from stretching rate of 0.1 mm/s to 5 mm/s.Moreover,a dielectric strength predictor based on configurational stress is adopted to describe the experimental data.According to the predictor,the loading rate affects the dielectric strength of the elastomer mainly by influencing the evolution of the inelastic deformation.
基金supported by the National Natural Science Foundation of China(No.21071115)the Shaanxi Province Natural Science Foundation Research Project(Nos.2020JZ–44 and 2021JZ–44)+1 种基金the Key Science and Technology Innovation Team of Shaanxi Province(No.2019TD–007)Northwest University 2023 college students innovation and entrepreneurship training program project(No.2023354).
文摘Next generation power system needs dielectrics with increased dielectric energy density.However,the low energy density of dielectrics limits their development.Here,an asymmetric trilayered nanocomposite,with a transition layer(TL),an insulation layer(IL),and a polarization layer(PL),is designed based on poly(vinylidene fluoride)-polymethyl methacrylate(PVDF-PMMA)matrix using KNbO_(3)(KN)and TiO_(2)(TO)as the nanofillers.The morphology and defect control of the two-dimensional nano KN and nano TO fillers are realized via a hydrothermal method to increase the composite breakdown strength(E_(b))and the composite energy density(U_(e)).The asymmetric trilayered structure leads to a gradient electric field distribution,and the KN and TO nanosheets block charges transfer along z direction.As a result,the development path of the electrical trees is greatly curved,and E_(b) is effectively improved.And the Ue value of the nanocomposites reaches 17.79 J·cm^(-3) at 523 MV·m^(-1).On the basis,the composite Ue is further improved by defect control in TO nanosheets.The nanocomposite KN/TO/PVDF-PMMA containing TO with less oxygen vacancy concentration(calcined at oxygen atmosphere)acquires a high Ue of 21.61 J·cm^(-3) at 548 MV·m^(-1).This study provides an idea for improving the energy storage performance by combining the design of the composite dielectric structure and the control of nanofillers’defect and morphology.
文摘聚合物纳米复合介质的击穿强度与纳米填充颗粒的质量分数、粒径和表面处理密切相关。以不同表面处理的纳米SiO2颗粒为填料，制备了不同填充质量分数、粒径的纳米SiO2／低密度聚乙烯（low density polyethylene,LDPE）复合介质，测试了其在交流、直流正极性和直流负极性3种不同类型电场下的击穿场强。结果表明：在所研究范围内，填充纳米SiO2颗粒可以提高低密度聚乙烯的击穿场强，并且随着填充质量分数的增加，复合介质的击穿场强有升高的趋势。纳米颗粒填充质量分数相同时，在12～16am粒径下，复合介质的击穿场强有随纳米SiO2粒径的升高而降低的趋势；在7nm小粒径下，可能由于纳米颗粒容易团聚，导致击穿场强较粒径大时要低。另外，纳米SiO2颗粒表面经疏水性处理后，能够有效提高复合介质的击穿场强。
基金H.Li,L.Ren,and D.Ai acknowledge the support from the China Scholarship Council(CSC).
文摘The exploration of high-energy-density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applications.The energy density of a capacitor is strongly dependent on dielectric constant and breakdown strength of a dielectric material.Here,we demonstrate a class of solution-processable polymer nanocomposites exhibiting a concurrent improvement in dielectric constant and breakdown strength,which typically show a negative correlation in conventional dielectric materials,along with a reduction in dielectric loss.The excellent performance is enabled by the elegant combination of nanostructured barium titanate and boron nitride fillers with complementary functionalities.The ternary polymer nanocomposite with the optimized filler compositions delivers a discharged energy density of 2.92 J cm^−3 and a Weibull breakdown strength of 547 MV m^−1 at 150℃,which are 83%and 25%,respectively,greater than those of the pristine polymer.The conduction behaviors including interfacial barrier and carrier transport process have been investigated to rationalize the energy storage performance of ternary polymer nanocomposite.This contribution provides a new design paradigm for scalable high-temperature polymer film capacitors.
