Self-assembled monolayers （SAMs） of （3-mercaptopropy） trimethoxysilane （3-MtrF） chemisorbed on silver surfaces were chemically ＂modified by 1-octadecanethiol to form self-assembled mixed-monolayers （SAMM） and...Self-assembled monolayers （SAMs） of （3-mercaptopropy） trimethoxysilane （3-MtrF） chemisorbed on silver surfaces were chemically ＂modified by 1-octadecanethiol to form self-assembled mixed-monolayers （SAMM） and the co-polymer of N-vinylcarbazole and methyl methacrylate ester （to form complex selfassembled film （CSAF））. The oxidation resistance of these barriers on silver surfaces and some influential factors concerned processes were analyzed by electrochemical impedance spectroscopy （EIS） in a 10% NaOH aqueous solution at oxidation potential. X-ray diffraction （XRD） spectroscopy shows that the oxidation occurring on the silver surface may be restrained effectively due to the coating barrier, and CSAF（Ⅱ） is the best one. Studies also reveal that oxide processes of bare silver and a series of modified silver electrodes in a 10% NaOH aqueous solution are of more than two relaxation time constants.展开更多
DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of c...DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of complex converter networks gets complicated.Because the reference frames of different converters might not fully align,depending on the structure.Thus,in order to find an accurate impedance model of a complex network for stability analysis,converting the impedances of different converters into a common reference frame is required.This paper presents a comprehensive investigation on the transformation of dq impedances to a common reference frame in complex converter networks.Four different methods are introduced and analyzed in a systematic way.Moreover,a rigorous comparison among these approaches is carried out,where the method with the simplest transformation procedure is finally suggested for the modeling of complex converter networks.The performed analysis is verified by injecting two independent small-signal perturbations into the d and the q axis,and doing a point-by-point impedance measurement.展开更多
Complex permittivity and electrical impedance have been measured along the c-axis in single crystals BaFe_2 As_2,which are the conductors known as the parent compound of 122-type iron superconductor. The resultant rel...Complex permittivity and electrical impedance have been measured along the c-axis in single crystals BaFe_2 As_2,which are the conductors known as the parent compound of 122-type iron superconductor. The resultant relative errors defined in the study indicate the existence of the transformation between complex permittivity and electrical impedance in the conductors, and these two physics quantities possibly reveal different aspects of the consistent superconductivityrelevant physics picture.展开更多
In this work, the self-assembled monolayer of Schiff base was first investigated using electrochemical impedance spectroscopy (EIS). The complexation Of Cu2+ with the Schiff base: was also detected with EIS method. Th...In this work, the self-assembled monolayer of Schiff base was first investigated using electrochemical impedance spectroscopy (EIS). The complexation Of Cu2+ with the Schiff base: was also detected with EIS method. The approximate linear relationship between Cu2+ and the reaction resistance (R-r) was observed. All the results suggest that the electrochemical property of Schiff base could be studied conveniently by means of forming self-assembled monolayer.展开更多
In this paper, the adsorption process of calmodulin (CaM) on Au substrate was first investigated with electrochemical impedance spectroscopy (EIS) method. The result reveals that the adsorption of the protein-calmodu...In this paper, the adsorption process of calmodulin (CaM) on Au substrate was first investigated with electrochemical impedance spectroscopy (EIS) method. The result reveals that the adsorption of the protein-calmodulin contains two steps, i.e., one short quick step followed by a slow one. The complexation of calmodulin with Ca2+ was also first probed using EIS technique, in which the complexation of CaM with Ca2+ could be reflected by the change of apparent membrane capacitance(Capp) clearly. In all above measurements, a redox couple Fe(CN)63-/ Fe(CN)64- was used as probing-pin to reflect all the changes occurring in the above process. Our work suggests that some biological processes of CaM could be studied using EIS method conveniently.展开更多
Based on the complex effective conductivity method, a closed-form expression for the internal impedance of mixed carbon nanotube （CNT） bundles, in which the number of CNTs for a given diameter follows a Gaussian dis...Based on the complex effective conductivity method, a closed-form expression for the internal impedance of mixed carbon nanotube （CNT） bundles, in which the number of CNTs for a given diameter follows a Gaussian distribution, is proposed in this paper. It can appropriately capture the skin effect as well as the temperature effect of mixed CNT bundles. The results of the closed-form expression and the numerical calculation are compared with various mean diameters, standard deviations, and temperatures. It is shown that the proposed model has very high accuracy in the whole frequency range considered, with maximum errors of 1% and 2.3% for the resistance and the internal inductance, respectively. Moreover, by using the proposed model, the high-frequency electrical characteristics of mixed CNT bundles are deeply analyzed to provide helpful design guidelines for their application in future high-performance three-dimensional integrated circuits.展开更多
The ultrafine CexMg0.06Zr1-xO1.94 （ x = 0 16% ） powders were synthesized by a chemical co-precipitated method. The pressed compacts were sintered in air at 1300, 1400, 1500, 1600℃ for 3 h, respectively. The phase o...The ultrafine CexMg0.06Zr1-xO1.94 （ x = 0 16% ） powders were synthesized by a chemical co-precipitated method. The pressed compacts were sintered in air at 1300, 1400, 1500, 1600℃ for 3 h, respectively. The phase of the ceramics was characterized by the X-ray diffraction （XRD） method. The conductivity of the ceramics was measured by the AC complex impedance technique at 700- 1200 ℃. The ratio of the cubic phase in the ceramics improves with increasing CeO2 content, leading to a enlargement of the oxygen ionic migration channel. The contact resistance between conductive phase particles decreases with increasing CeO2 content, leading to a lower migration hindrance of the oxygen ionic. Consequently, the ionic conductivity of the ceramics improves with increas- ing CeO2 content. Additionally, an analysis for this phenomenon was also presented.展开更多
To address the need for the on-site measurement of aging oil, in this paper, we propose an impedance-based microsensor for analyzing the moisture content in engine oil. Using a microfabrication process, we fabricated ...To address the need for the on-site measurement of aging oil, in this paper, we propose an impedance-based microsensor for analyzing the moisture content in engine oil. Using a microfabrication process, we fabricated an interdigitated microelectrode and integrated it with a 3 D-printed microcontainer to produce a microsensor that can detect changes in the permittivity of oil. When the moisture content in oil increases, this sensor can detect the resulting change in the oil impedance, which is related to its permittivity, and then determine the degree to which the oil has aged. The test results show that the proposed microsensor has the advantages of being small and having high sensitivity, good accuracy, and the ability to be combined with hand-held instruments.The proposed method is expected to be used for the rapid, low cost, on-site determination of oil aging.展开更多
A series of compounds Ba5-xSrxGdTi3V7O30 (x = 0 - 5), belonging to tungsten bronze family were prepared by a high-temperature solid-state reaction route. Using X-Ray diffraction technique and Scanning Electron Microgr...A series of compounds Ba5-xSrxGdTi3V7O30 (x = 0 - 5), belonging to tungsten bronze family were prepared by a high-temperature solid-state reaction route. Using X-Ray diffraction technique and Scanning Electron Micrograph, the formation and surface morphology of the compounds were studied. The X-Ray diffraction study informs the formation of single-phase orthorhombic structures. The substitution of Sr ion with increasing concentration in the compounds as per formula resulted in a variation of the electrical properties. Study of electrical properties using impedance analyzer exhibits: 1) the presence of negative temperature coefficients of resistance (NTCR) behavior;2) presence of temperature dependent electrical relaxation phenomena;3) evidences of single electrical relaxation attributed to the presence of bulk contribution to the electrical properties for pure Ba5GdTi3V7O30 compound;4) an enhancement in the barrier to the mobility of charge carriers on Sr-substitution. The effects of Sr on changes in the electrical conductivity as a function of temperature at different frequency are described based on impedance spectrum analysis.展开更多
In this contribution we briefly discuss several analysis techniques for impedance spectroscopy experiments.A number of different approaches,which differ even by the definition of the problem,are used in the literature...In this contribution we briefly discuss several analysis techniques for impedance spectroscopy experiments.A number of different approaches,which differ even by the definition of the problem,are used in the literature.Some aimed towards finding an equivalent circuit.Others aimed towards finding directly dielectric properties of the material under an assumed model.Others towards finding distribution of relaxation times,either parametric or point-by point.No matter what the approach is,this will always be an ill-posed problem in the sense that there exist a large number of possible solutions that solve the problem (mathematically) equally well.Therefore some a-priori knowledge about the system must he used.In addition,we should remember that the ultimate goal is to get physical insight about the system.展开更多
Our previous study reported the influences of different complexing agents on electroless nickel （EN） by examining the properties of the deposits. In the present work, the effects of four common-used complexing agent...Our previous study reported the influences of different complexing agents on electroless nickel （EN） by examining the properties of the deposits. In the present work, the effects of four common-used complexing agents on EN deposition rate and the stability of solution pH values were examined, either with an acetic pH buffer agent or absent of them. It is indicated that the pH buffeting effect of them is dominative when the EN solution is lack of the pH buffer. Under this situation, the EN deposition rate increases with the concentration of complexing agents increasing. The EN deposition rate decreases with fin＇ther adding the complexing agent when the solution already has enough pH buffer capability. Electrochemical impedance spectroscopy obtained during EN deposition illustrates that, in this case, the enhanced reaction resistance is the main reason for a lower deposition rate. However, the influence of polarization caused by mass transfer is not negligible at high complex ratio for sodium citrate and malic acid EN solutions.展开更多
Unlike the real-valued plane wave reflection coefficient(PRC)at the pre-critical incident angles,the frequency-and depth-dependent spherical-wave reflection coefficient(SRC)is more accurate and always a complex value,...Unlike the real-valued plane wave reflection coefficient(PRC)at the pre-critical incident angles,the frequency-and depth-dependent spherical-wave reflection coefficient(SRC)is more accurate and always a complex value,which contains more reflection amplitude and phase information.In near field,the imaginary part of complex SRC(phase)cannot be ignored,but it is rarely considered in seismic inversion.To promote the practical application of spherical-wave seismic inversion,a novel spherical-wave inversion strategy is implemented.The complex-valued spherical-wave synthetic seismograms can be obtained by using a simple harmonic superposition model.It is assumed that geophone can only record the real part of complex-valued seismogram.The imaginary part can be further obtained by the Hilbert transform operator.We also propose the concept of complex spherical-wave elastic impedance(EI)and the complex spherical-wave EI equation.Finally,a novel complex spherical-wave EI inversion approach is proposed,which can fully use the reflection information of amplitude,phase,and frequency.With the inverted complex spherical-wave EI,the velocities and density can be further extracted.Synthetic data and field data examples show that the elastic parameters can be reasonably estimated,which illustrate the potential of our spherical-wave inversion approach in practical applications.展开更多
The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 ...The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 Hz)at different temperatures(28-500℃).Nyquist plot reveals the presence of bulk effect only.The bulk resistance of the compound decreases with rise in temperature which shows the negative temperature coefficient of resistance(NTCR)like a semiconductor.The ac conductivity spectrum was found to obey Jonscher’s universal power law.DC conductivity(bulk)with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity and the activation energy found to be 0.97 eV.展开更多
基金The National Natural Science Foundation of China(Nos.60371027,60171005).
文摘Self-assembled monolayers （SAMs） of （3-mercaptopropy） trimethoxysilane （3-MtrF） chemisorbed on silver surfaces were chemically ＂modified by 1-octadecanethiol to form self-assembled mixed-monolayers （SAMM） and the co-polymer of N-vinylcarbazole and methyl methacrylate ester （to form complex selfassembled film （CSAF））. The oxidation resistance of these barriers on silver surfaces and some influential factors concerned processes were analyzed by electrochemical impedance spectroscopy （EIS） in a 10% NaOH aqueous solution at oxidation potential. X-ray diffraction （XRD） spectroscopy shows that the oxidation occurring on the silver surface may be restrained effectively due to the coating barrier, and CSAF（Ⅱ） is the best one. Studies also reveal that oxide processes of bare silver and a series of modified silver electrodes in a 10% NaOH aqueous solution are of more than two relaxation time constants.
基金The support of the first and fourth authors is given by National Key R&D Program of China,2018YFB0905200.The support for the second and third authors is coming from BIRD171227/17 project of the University of Padova.
文摘DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of complex converter networks gets complicated.Because the reference frames of different converters might not fully align,depending on the structure.Thus,in order to find an accurate impedance model of a complex network for stability analysis,converting the impedances of different converters into a common reference frame is required.This paper presents a comprehensive investigation on the transformation of dq impedances to a common reference frame in complex converter networks.Four different methods are introduced and analyzed in a systematic way.Moreover,a rigorous comparison among these approaches is carried out,where the method with the simplest transformation procedure is finally suggested for the modeling of complex converter networks.The performed analysis is verified by injecting two independent small-signal perturbations into the d and the q axis,and doing a point-by-point impedance measurement.
基金Project supported by the National Natural Science Foundation of China(Grant No.11004106)the National Basic Research Program of China(Grant No.2015CB946502)+1 种基金the Chinese Academy of Sciences(Grant No.SPRP-B:XDB25000000)the Youth Innovation Promotion Association of Chinese Academy of Sciences
文摘Complex permittivity and electrical impedance have been measured along the c-axis in single crystals BaFe_2 As_2,which are the conductors known as the parent compound of 122-type iron superconductor. The resultant relative errors defined in the study indicate the existence of the transformation between complex permittivity and electrical impedance in the conductors, and these two physics quantities possibly reveal different aspects of the consistent superconductivityrelevant physics picture.
基金the NSFC (29973026) and Beijing Natural Science Foundation (2992007).
文摘In this work, the self-assembled monolayer of Schiff base was first investigated using electrochemical impedance spectroscopy (EIS). The complexation Of Cu2+ with the Schiff base: was also detected with EIS method. The approximate linear relationship between Cu2+ and the reaction resistance (R-r) was observed. All the results suggest that the electrochemical property of Schiff base could be studied conveniently by means of forming self-assembled monolayer.
文摘In this paper, the adsorption process of calmodulin (CaM) on Au substrate was first investigated with electrochemical impedance spectroscopy (EIS) method. The result reveals that the adsorption of the protein-calmodulin contains two steps, i.e., one short quick step followed by a slow one. The complexation of calmodulin with Ca2+ was also first probed using EIS technique, in which the complexation of CaM with Ca2+ could be reflected by the change of apparent membrane capacitance(Capp) clearly. In all above measurements, a redox couple Fe(CN)63-/ Fe(CN)64- was used as probing-pin to reflect all the changes occurring in the above process. Our work suggests that some biological processes of CaM could be studied using EIS method conveniently.
基金Project supported by the National Science and Technology Major Project of China(Grant No.2015ZX03001004)the National Natural Science Foundation of China(Grant Nos.61604113,61625403,61334003,61376039,61574104,and 61474088)
文摘Based on the complex effective conductivity method, a closed-form expression for the internal impedance of mixed carbon nanotube （CNT） bundles, in which the number of CNTs for a given diameter follows a Gaussian distribution, is proposed in this paper. It can appropriately capture the skin effect as well as the temperature effect of mixed CNT bundles. The results of the closed-form expression and the numerical calculation are compared with various mean diameters, standard deviations, and temperatures. It is shown that the proposed model has very high accuracy in the whole frequency range considered, with maximum errors of 1% and 2.3% for the resistance and the internal inductance, respectively. Moreover, by using the proposed model, the high-frequency electrical characteristics of mixed CNT bundles are deeply analyzed to provide helpful design guidelines for their application in future high-performance three-dimensional integrated circuits.
文摘The ultrafine CexMg0.06Zr1-xO1.94 （ x = 0 16% ） powders were synthesized by a chemical co-precipitated method. The pressed compacts were sintered in air at 1300, 1400, 1500, 1600℃ for 3 h, respectively. The phase of the ceramics was characterized by the X-ray diffraction （XRD） method. The conductivity of the ceramics was measured by the AC complex impedance technique at 700- 1200 ℃. The ratio of the cubic phase in the ceramics improves with increasing CeO2 content, leading to a enlargement of the oxygen ionic migration channel. The contact resistance between conductive phase particles decreases with increasing CeO2 content, leading to a lower migration hindrance of the oxygen ionic. Consequently, the ionic conductivity of the ceramics improves with increas- ing CeO2 content. Additionally, an analysis for this phenomenon was also presented.
基金the financial support provided by the National Natural Science Foundation of China (NSFC No. U1733120, 61601469, 61674114, 61701475, 91743110, 21861132001)National Key R&D Program of China (2017YFF0204604, 2018YFE0118700)+4 种基金Tianjin Applied Basic Research and Advanced Technology (17JCJQJC43600)the 111 Project (B07014)the Initial Scientific Research Fund of State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University (No. Pilq1902)the Foundation for Talent Scientists of Nanchang Institute for Micro-technology of Tianjin Universitythe Open Research Fund of Key Laboratory of MEMS of Ministry of Education, Southeast University。
文摘To address the need for the on-site measurement of aging oil, in this paper, we propose an impedance-based microsensor for analyzing the moisture content in engine oil. Using a microfabrication process, we fabricated an interdigitated microelectrode and integrated it with a 3 D-printed microcontainer to produce a microsensor that can detect changes in the permittivity of oil. When the moisture content in oil increases, this sensor can detect the resulting change in the oil impedance, which is related to its permittivity, and then determine the degree to which the oil has aged. The test results show that the proposed microsensor has the advantages of being small and having high sensitivity, good accuracy, and the ability to be combined with hand-held instruments.The proposed method is expected to be used for the rapid, low cost, on-site determination of oil aging.
文摘A series of compounds Ba5-xSrxGdTi3V7O30 (x = 0 - 5), belonging to tungsten bronze family were prepared by a high-temperature solid-state reaction route. Using X-Ray diffraction technique and Scanning Electron Micrograph, the formation and surface morphology of the compounds were studied. The X-Ray diffraction study informs the formation of single-phase orthorhombic structures. The substitution of Sr ion with increasing concentration in the compounds as per formula resulted in a variation of the electrical properties. Study of electrical properties using impedance analyzer exhibits: 1) the presence of negative temperature coefficients of resistance (NTCR) behavior;2) presence of temperature dependent electrical relaxation phenomena;3) evidences of single electrical relaxation attributed to the presence of bulk contribution to the electrical properties for pure Ba5GdTi3V7O30 compound;4) an enhancement in the barrier to the mobility of charge carriers on Sr-substitution. The effects of Sr on changes in the electrical conductivity as a function of temperature at different frequency are described based on impedance spectrum analysis.
文摘In this contribution we briefly discuss several analysis techniques for impedance spectroscopy experiments.A number of different approaches,which differ even by the definition of the problem,are used in the literature.Some aimed towards finding an equivalent circuit.Others aimed towards finding directly dielectric properties of the material under an assumed model.Others towards finding distribution of relaxation times,either parametric or point-by point.No matter what the approach is,this will always be an ill-posed problem in the sense that there exist a large number of possible solutions that solve the problem (mathematically) equally well.Therefore some a-priori knowledge about the system must he used.In addition,we should remember that the ultimate goal is to get physical insight about the system.
文摘Our previous study reported the influences of different complexing agents on electroless nickel （EN） by examining the properties of the deposits. In the present work, the effects of four common-used complexing agents on EN deposition rate and the stability of solution pH values were examined, either with an acetic pH buffer agent or absent of them. It is indicated that the pH buffeting effect of them is dominative when the EN solution is lack of the pH buffer. Under this situation, the EN deposition rate increases with the concentration of complexing agents increasing. The EN deposition rate decreases with fin＇ther adding the complexing agent when the solution already has enough pH buffer capability. Electrochemical impedance spectroscopy obtained during EN deposition illustrates that, in this case, the enhanced reaction resistance is the main reason for a lower deposition rate. However, the influence of polarization caused by mass transfer is not negligible at high complex ratio for sodium citrate and malic acid EN solutions.
基金the sponsorship of the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(Grant No.2021QNLM0200016)National Natural Science Foundation of China(42030103,41974119)Science Foundation from Innovation and Technology Support Program for Young Scientists in Colleges of Shandong province and Ministry of Science and Technology of China(2019RA2136)
文摘Unlike the real-valued plane wave reflection coefficient(PRC)at the pre-critical incident angles,the frequency-and depth-dependent spherical-wave reflection coefficient(SRC)is more accurate and always a complex value,which contains more reflection amplitude and phase information.In near field,the imaginary part of complex SRC(phase)cannot be ignored,but it is rarely considered in seismic inversion.To promote the practical application of spherical-wave seismic inversion,a novel spherical-wave inversion strategy is implemented.The complex-valued spherical-wave synthetic seismograms can be obtained by using a simple harmonic superposition model.It is assumed that geophone can only record the real part of complex-valued seismogram.The imaginary part can be further obtained by the Hilbert transform operator.We also propose the concept of complex spherical-wave elastic impedance(EI)and the complex spherical-wave EI equation.Finally,a novel complex spherical-wave EI inversion approach is proposed,which can fully use the reflection information of amplitude,phase,and frequency.With the inverted complex spherical-wave EI,the velocities and density can be further extracted.Synthetic data and field data examples show that the elastic parameters can be reasonably estimated,which illustrate the potential of our spherical-wave inversion approach in practical applications.
基金The authors(PN and BB)acknowledge the financial support through DRS-I under SAP of UGC for the development of research work in the School of Physics,SU.
文摘The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 Hz)at different temperatures(28-500℃).Nyquist plot reveals the presence of bulk effect only.The bulk resistance of the compound decreases with rise in temperature which shows the negative temperature coefficient of resistance(NTCR)like a semiconductor.The ac conductivity spectrum was found to obey Jonscher’s universal power law.DC conductivity(bulk)with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity and the activation energy found to be 0.97 eV.
