Capacitor voltage transformer (CVT), which is with simple structure, convenient maintenance, functional diversity and high impact pressure strength, is widely used. And its capacitance and dielectric loss Angle measur...Capacitor voltage transformer (CVT), which is with simple structure, convenient maintenance, functional diversity and high impact pressure strength, is widely used. And its capacitance and dielectric loss Angle measurement is an important test on testing the insulation of the equipment. This paper is mainly to introduce and discuss one of the CVT test methods——the “self excitation method”, combined with the actual situation encountered in the work, sums up and expounds the maintenance of CVT and preventive test of influence factors.展开更多
Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestab...Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.展开更多
The studied sample is a metallic glass in Fe-Si-B system. It is developed with the nominal composition of Fe735-Cu1-Ta3-Si13.5-B9 by single-roller melt spinning technique in air. The dielectric constant and loss facto...The studied sample is a metallic glass in Fe-Si-B system. It is developed with the nominal composition of Fe735-Cu1-Ta3-Si13.5-B9 by single-roller melt spinning technique in air. The dielectric constant and loss factor have been measured both for as cast and annealed samples using Agilent Impedance analyzer. They are found to decrease with frequency up to 10 MHz and remain constant afterwards. The decrease of dielectric constant and loss factor with frequency is due to ceasing of orientational polarizability. Their constancy is owing to presence of only electronic contribution to its polarizability above 10 MHz. Three distinct regions （1-4 MHz, 4-10 MHz and 10 MHz-1 GHz） also noticed from its frequency dependence, which might make it useful in switching and sensor devices. The temperature dependence of dielectric constant and loss factor maintain inverse relationship： （1） dielectric constant increases, and （2） loss factor decreases with annealing temperature for structural relaxation due to thermal agitation.展开更多
With the interest in using lead-free materials to replace lead-containing materials increasing,the use of Na_（0.5）Bi_（0.5）TiO_3（NBT） has come into our sight.We studied the composition of NBT and found that NaBiT...With the interest in using lead-free materials to replace lead-containing materials increasing,the use of Na_（0.5）Bi_（0.5）TiO_3（NBT） has come into our sight.We studied the composition of NBT and found that NaBiTi_6O_（14） ceramics can be compositionally tuned by Mg-doping on the Ti-site to optimize the dielectric properties.In this study,Mg-doped NaBiTi_6O_（14）（NaBi（Ti_（0.98）Mg_（0.02））_60_（14-d）） ceramics were prepared by a conventional mixed oxide route at different sintering temperatures,and their dielectric properties have been studied at a wide temperature range.X-ray diffraction（XRD） patterns of the NBT-based ceramics indicate that all samples have a pure phase without any secondary impurity phase.The experimental data show that after Mg-doping,the relative permittivity and dielectric loss become lower at 1040,1060,and1080 ℃ except 1020 ℃ and at different frequencies from 10 kHz,100 kHz to 1 MHz.Take 1060 ℃ for example,when the sintering temperature is 1060 ℃ at 1 MHz,the minimum relative permittivity of NaBiTi_6O_（14） is 32.9 and the minimum dielectric loss is 0.01417,the relative permittivity of NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） under the same condition is 25.8 and the dielectric loss is 0.000104.We explored the mechanism of Mg-doping and surprisingly found that the dielectric property of NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） becomes better owing to Mg-doping.Thus,NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） can be used in microwave ceramics and applied to new energy materials.展开更多
文摘Capacitor voltage transformer (CVT), which is with simple structure, convenient maintenance, functional diversity and high impact pressure strength, is widely used. And its capacitance and dielectric loss Angle measurement is an important test on testing the insulation of the equipment. This paper is mainly to introduce and discuss one of the CVT test methods——the “self excitation method”, combined with the actual situation encountered in the work, sums up and expounds the maintenance of CVT and preventive test of influence factors.
基金supported by the Universiti Sains Malaysia(USM) fellowship(APEX 91002/JHEA/ATSG4001)fundamental research grant scheme(FRGS) under grant number of 203/PBAHAN/6071263
文摘Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.
文摘The studied sample is a metallic glass in Fe-Si-B system. It is developed with the nominal composition of Fe735-Cu1-Ta3-Si13.5-B9 by single-roller melt spinning technique in air. The dielectric constant and loss factor have been measured both for as cast and annealed samples using Agilent Impedance analyzer. They are found to decrease with frequency up to 10 MHz and remain constant afterwards. The decrease of dielectric constant and loss factor with frequency is due to ceasing of orientational polarizability. Their constancy is owing to presence of only electronic contribution to its polarizability above 10 MHz. Three distinct regions （1-4 MHz, 4-10 MHz and 10 MHz-1 GHz） also noticed from its frequency dependence, which might make it useful in switching and sensor devices. The temperature dependence of dielectric constant and loss factor maintain inverse relationship： （1） dielectric constant increases, and （2） loss factor decreases with annealing temperature for structural relaxation due to thermal agitation.
基金Project supported by the Fund from the Hubei Provincial Department of Education,China(Grant No.D20161006)
文摘With the interest in using lead-free materials to replace lead-containing materials increasing,the use of Na_（0.5）Bi_（0.5）TiO_3（NBT） has come into our sight.We studied the composition of NBT and found that NaBiTi_6O_（14） ceramics can be compositionally tuned by Mg-doping on the Ti-site to optimize the dielectric properties.In this study,Mg-doped NaBiTi_6O_（14）（NaBi（Ti_（0.98）Mg_（0.02））_60_（14-d）） ceramics were prepared by a conventional mixed oxide route at different sintering temperatures,and their dielectric properties have been studied at a wide temperature range.X-ray diffraction（XRD） patterns of the NBT-based ceramics indicate that all samples have a pure phase without any secondary impurity phase.The experimental data show that after Mg-doping,the relative permittivity and dielectric loss become lower at 1040,1060,and1080 ℃ except 1020 ℃ and at different frequencies from 10 kHz,100 kHz to 1 MHz.Take 1060 ℃ for example,when the sintering temperature is 1060 ℃ at 1 MHz,the minimum relative permittivity of NaBiTi_6O_（14） is 32.9 and the minimum dielectric loss is 0.01417,the relative permittivity of NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） under the same condition is 25.8 and the dielectric loss is 0.000104.We explored the mechanism of Mg-doping and surprisingly found that the dielectric property of NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） becomes better owing to Mg-doping.Thus,NaBi（Ti_（0.98）Mg_（0.02））_60_（14-δ） can be used in microwave ceramics and applied to new energy materials.
