Conductive n type a Si∶H∶Y alloy films with the conductivity as high as 60 S/cm have been deposited on Si substrate by radio frequency sputtering. In the temperature range 20~300 K, for samples with large Y conte...Conductive n type a Si∶H∶Y alloy films with the conductivity as high as 60 S/cm have been deposited on Si substrate by radio frequency sputtering. In the temperature range 20~300 K, for samples with large Y contents, the thermally activated conduction is also observed and the plots of lg σ vs. 1/ T can be fitted by two linear functions with different slopes. The corresponding temperatures of the kinks between the two straight lines depend on the Y contents in the samples. For small Y content films, the conductivities can be fitted to the funciton σ∝ exp (-1/ T 1/4 ). The present results are interpreted using different conduction mechanisms in different temperature ranges for samples with different Y contents.展开更多
The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low...The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low-temperature conductive silver paste.Afterwards,the effect of the conductive organic carrier on the properties of the low-temperature conductive silver paste was determined by IR,DMA and SEM.The results revealed that the prepared conductive paste has good conductivity,film-forming performance,printing performance,low-temperature curing performance,and anti-aging performance.When the mass percentage of the bonding phase/conductive phase was 40/60,the lowest volume resistivity of the conductive silver paste was 4.9×10^(−6)Ω⋅cm,and the conductivity was the best.展开更多
A new numerical technique named interval finite difference method is proposed for the steady-state temperature field prediction with uncertainties in both physical parameters and boundary conditions. Interval variable...A new numerical technique named interval finite difference method is proposed for the steady-state temperature field prediction with uncertainties in both physical parameters and boundary conditions. Interval variables are used to quantitatively describe the uncertain parameters with limited information. Based on different Taylor and Neumann series, two kinds of parameter perturbation methods are presented to approximately yield the ranges of the uncertain temperature field. By comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method for solving steady-state heat conduction problem with uncertain-but-bounded parameters.展开更多
Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows depende...Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K展开更多
The changes of resistivity of conductive asphalt concrete at different temperatures were studied,and positive temperature coefficient(PTC)modelwas established to estimate the influence of temperature on the resistiv...The changes of resistivity of conductive asphalt concrete at different temperatures were studied,and positive temperature coefficient(PTC)modelwas established to estimate the influence of temperature on the resistivity quantitatively,which eliminated the interference with conductivity evaluation brought by temperature variation.Finally,the analysis of temperature cycling test results proves that the changes of percolation network structure caused by temperature variation prompt the emergence of PTC of conductive asphalt concrete.展开更多
This paper presents the substrate temperature dependence of opto-electrical properties for transparent conducting Al-doped ZnO films prepared on polyisocyanate (PI) substrates by r f sputtering. Polycrystalline ZnO:Al...This paper presents the substrate temperature dependence of opto-electrical properties for transparent conducting Al-doped ZnO films prepared on polyisocyanate (PI) substrates by r f sputtering. Polycrystalline ZnO:Al films with good adherence to the substrates having a (002) preferred orientation have been obtained with resistivities in the range from 4.1×10-3to 5.3×104 Ωcm, carrier densities more than 2.6×1020 cm-3 and Hall mobilities between 5.78 and 13.11 cm2/V/s for films. The average transmittance reaches 75% in the visible spectrum. The quality of obtained films depends on substrate temperature during film fabrication.展开更多
Ta-doped titanium dioxide films are deposited on fused quartz substrates using the rf magnetron sputtering technique at different substrate temperatures. After post-annealing at 550℃ in a vacuum, all the films are cr...Ta-doped titanium dioxide films are deposited on fused quartz substrates using the rf magnetron sputtering technique at different substrate temperatures. After post-annealing at 550℃ in a vacuum, all the films are crystallized into the polycrystalline anatase TiO2 structure. The effects of substrate temperature from room temperature up to 350℃ on the structure, morphology, and photoelectric properties of Ta-doped titanium dioxide films are analyzed. The average transmittance in the visible region(400-800 nm) of all films is more than 73%.The resistivity decreases firstly and then increases moderately with the increasing substrate temperature. The polycrystalline film deposited at 150℃ exhibits a lowest resistivity of 7.7 × 10^-4Ω·cm with the highest carrier density of 1.1×10^21 cm^-3 and the Hall mobility of 7.4 cm^2·V^-1s^-1.展开更多
In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the...In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results.展开更多
This study aims at evidencing the effects of lime treatment on the microstructure and hydraulic conductivityof a compacted expansive clay, with emphasis put on the effect of lime hydration and modification.For this pu...This study aims at evidencing the effects of lime treatment on the microstructure and hydraulic conductivityof a compacted expansive clay, with emphasis put on the effect of lime hydration and modification.For this purpose, evolutions of hydraulic conductivity were investigated for both lime-treatedand untreated soil specimens over 7 d after full saturation of the specimens and their microstructureswere observed at the end. Note that for the treated specimen, dry clay powder was mixed with quicklimeprior to compaction in order to study the effect of lime hydration. It is observed that lime hydration andmodification did not affect the intra-aggregate pores but increased the inter-aggregates pores size. Thisincrease gave rise to an increase of hydraulic conductivity. More precisely, the hydraulic conductivity oflime-treated specimen increased progressively during the first 3 d of modification phase and stabilisedduring the next 4 d which correspond to a short period prior to the stabilisation phase. The microstructureobservation showed that stabilisation reactions took place after 7 d. Under the effect of stabilisation,a decreasing hydraulic conductivity can be expected in longer time due to the formation ofcementitious compounds. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the or...As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the orthorhombic perovskite GdFeO 3 type. XPS analysis indicates that chrome ions are in different valence state. The introduction of Ca 2+ into the lattice induces the oxidation of Cr 3+ to Cr 6+ . With x increasing, the amount of Cr 6+ increases. The present of the more Cr 6+ is one of the important factors that effect electric conductivity of La 1-x Ca x CrO 3.展开更多
To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a ...To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a frequency range of 100 Hz to 10 k Hz and an interval of 100 Hz are used to measure transmission characteristics of channels with lengths of 300 m, 800 m, 1300 m, and 1800 m. The correctness of the fitted channel characteristics by transmitting square wave, composite waves of different frequencies, and ASK modulation are verified. The results show that when the frequency of the signal is below 1500 Hz, the channel has very little effect on the signal. The signal compensated for amplitude and phase at the receiver is not as good as the uncompensated signal.Alternatively, when the signal frequency is above 1500 Hz, the channel distorts the signal. The quality of signal compensated for amplitude and phase at receiver is better than that of the uncompensated signal. Thus, we can select the appropriate frequency for XCTD system and the appropriate way to process the received signals. Signals below1500 Hz can be directly used at the receiving end. Signals above 1500 Hz are used after amplitude and phase compensation at the receiving end.展开更多
The crystal structure,magnetic and electrical properties of Bi(0.96)Pb(0.04) FeO3 and Bi(0.92)Pb(0.04)RE(0.04)FeO3(RE=La,Sm,Dy and Yb)polycrystalline samples were prepared by the flash autocombustion techn...The crystal structure,magnetic and electrical properties of Bi(0.96)Pb(0.04) FeO3 and Bi(0.92)Pb(0.04)RE(0.04)FeO3(RE=La,Sm,Dy and Yb)polycrystalline samples were prepared by the flash autocombustion technique.X-ray diffraction(XRD)measurements show that the rare-earth doped compositions crystallized in rhombohedral symmetry of space group R3 c.The undoped sample consisted needle shape particles while rare earth substitution preferred platelet like particles as clarified from high resolution transmission electron microscopy(HRTEM).Morphological features were examined using field emission scanning electron microscopy(FESEM).Magnetization measurements showed that Yb^3+ samples possessed the highest room temperature saturation magnetization while when Bi^3+ ions were substituted by La^3+ ions,a smaller MS(0.28 emu/g)was obtained.The coexistence of ferroelectric and magnetic transitions was detected using DSC and χM,indicating the multiferroic characteristics of Bi(0.92)Pb(0.04)RE(0.04)FeO3 crystallites.The Néel temperature shifted upwards with decreasing the ionic radius of rare earth ion.Nice correlation was established between microstructure,morphology and magnetic properties in view of the contribution of magnetocrystalline and shape anisotropy in the magnetic parameters values.展开更多
Understanding the substrate and temperature effect on thermal transport properties of transition metal dichalcogenides(TMDs)monolayers are crucial for their future applications.Herein,a dual-wavelength flash Raman(DF-...Understanding the substrate and temperature effect on thermal transport properties of transition metal dichalcogenides(TMDs)monolayers are crucial for their future applications.Herein,a dual-wavelength flash Raman(DF-Raman)method is used to measure the thermal conductivity of monolayer WS_(2) at a temperature range of 200–400 K.High measurement accuracy can be guaranteed in this method since the influence of both the laser absorption coefficient and temperature-Raman coefficient can be eliminated through normalization.The room-temperature thermal conductivity of suspended and supported WS_(2) are 28.5±2.1(30.3±2.0)and 15.4±1.9(16.9±2.1)W/(m·K),respectively,with a~50%reduction due to substrate effect.Molecular dynamics(MD)simulations reveal that the suppression of acoustic phonons is mainly responsible for the striking reduction.The behaviors of optical phonons are also unambiguously investigated using Raman spectroscopy,and the in-plane optical mode,E(Γ),is surprisingly found to be slightly enhanced while out-of-plane mode,A1g(Γ),is suppressed due to substrate interaction,mutually verified with MD results.Our study provides a solid understanding of the phonon transport behavior of WS_(2) with substrate interaction,which provides guidance for TMDs-based nanodevices.展开更多
文摘Conductive n type a Si∶H∶Y alloy films with the conductivity as high as 60 S/cm have been deposited on Si substrate by radio frequency sputtering. In the temperature range 20~300 K, for samples with large Y contents, the thermally activated conduction is also observed and the plots of lg σ vs. 1/ T can be fitted by two linear functions with different slopes. The corresponding temperatures of the kinks between the two straight lines depend on the Y contents in the samples. For small Y content films, the conductivities can be fitted to the funciton σ∝ exp (-1/ T 1/4 ). The present results are interpreted using different conduction mechanisms in different temperature ranges for samples with different Y contents.
基金fund for this work was provided by the“Research on Key Technologies of Photosensitive Conductive Silver Paste Based on Domestic Circuit Protection Micro Chip Components”(Project No.BE2020008 and Supporting Author:Chen P).
文摘The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low-temperature conductive silver paste.Afterwards,the effect of the conductive organic carrier on the properties of the low-temperature conductive silver paste was determined by IR,DMA and SEM.The results revealed that the prepared conductive paste has good conductivity,film-forming performance,printing performance,low-temperature curing performance,and anti-aging performance.When the mass percentage of the bonding phase/conductive phase was 40/60,the lowest volume resistivity of the conductive silver paste was 4.9×10^(−6)Ω⋅cm,and the conductivity was the best.
基金supported by the National Special Fund for Major Research Instrument Development(2011YQ140145)111 Project (B07009)+1 种基金the National Natural Science Foundation of China(11002013)Defense Industrial Technology Development Program(A2120110001 and B2120110011)
文摘A new numerical technique named interval finite difference method is proposed for the steady-state temperature field prediction with uncertainties in both physical parameters and boundary conditions. Interval variables are used to quantitatively describe the uncertain parameters with limited information. Based on different Taylor and Neumann series, two kinds of parameter perturbation methods are presented to approximately yield the ranges of the uncertain temperature field. By comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed method for solving steady-state heat conduction problem with uncertain-but-bounded parameters.
文摘Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K
基金Funded by the National Natural Science Foundation of China(No.51178348)
文摘The changes of resistivity of conductive asphalt concrete at different temperatures were studied,and positive temperature coefficient(PTC)modelwas established to estimate the influence of temperature on the resistivity quantitatively,which eliminated the interference with conductivity evaluation brought by temperature variation.Finally,the analysis of temperature cycling test results proves that the changes of percolation network structure caused by temperature variation prompt the emergence of PTC of conductive asphalt concrete.
基金This work is supported by the National Natural Srience Foundation of China(No.69876025 and No.60076006)Science and Technology Committee of Shandong Province and the Natural Science Foundation of Shandong Province.
文摘This paper presents the substrate temperature dependence of opto-electrical properties for transparent conducting Al-doped ZnO films prepared on polyisocyanate (PI) substrates by r f sputtering. Polycrystalline ZnO:Al films with good adherence to the substrates having a (002) preferred orientation have been obtained with resistivities in the range from 4.1×10-3to 5.3×104 Ωcm, carrier densities more than 2.6×1020 cm-3 and Hall mobilities between 5.78 and 13.11 cm2/V/s for films. The average transmittance reaches 75% in the visible spectrum. The quality of obtained films depends on substrate temperature during film fabrication.
基金Supported by the National Natural Science Foundation of China under Grant No 11374114
文摘Ta-doped titanium dioxide films are deposited on fused quartz substrates using the rf magnetron sputtering technique at different substrate temperatures. After post-annealing at 550℃ in a vacuum, all the films are crystallized into the polycrystalline anatase TiO2 structure. The effects of substrate temperature from room temperature up to 350℃ on the structure, morphology, and photoelectric properties of Ta-doped titanium dioxide films are analyzed. The average transmittance in the visible region(400-800 nm) of all films is more than 73%.The resistivity decreases firstly and then increases moderately with the increasing substrate temperature. The polycrystalline film deposited at 150℃ exhibits a lowest resistivity of 7.7 × 10^-4Ω·cm with the highest carrier density of 1.1×10^21 cm^-3 and the Hall mobility of 7.4 cm^2·V^-1s^-1.
文摘In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results.
基金the French National Research Agency for funding the present study within the project-TERDOUEST "Sustainable earthworks involving treated soils"
文摘This study aims at evidencing the effects of lime treatment on the microstructure and hydraulic conductivityof a compacted expansive clay, with emphasis put on the effect of lime hydration and modification.For this purpose, evolutions of hydraulic conductivity were investigated for both lime-treatedand untreated soil specimens over 7 d after full saturation of the specimens and their microstructureswere observed at the end. Note that for the treated specimen, dry clay powder was mixed with quicklimeprior to compaction in order to study the effect of lime hydration. It is observed that lime hydration andmodification did not affect the intra-aggregate pores but increased the inter-aggregates pores size. Thisincrease gave rise to an increase of hydraulic conductivity. More precisely, the hydraulic conductivity oflime-treated specimen increased progressively during the first 3 d of modification phase and stabilisedduring the next 4 d which correspond to a short period prior to the stabilisation phase. The microstructureobservation showed that stabilisation reactions took place after 7 d. Under the effect of stabilisation,a decreasing hydraulic conductivity can be expected in longer time due to the formation ofcementitious compounds. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
文摘As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the orthorhombic perovskite GdFeO 3 type. XPS analysis indicates that chrome ions are in different valence state. The introduction of Ca 2+ into the lattice induces the oxidation of Cr 3+ to Cr 6+ . With x increasing, the amount of Cr 6+ increases. The present of the more Cr 6+ is one of the important factors that effect electric conductivity of La 1-x Ca x CrO 3.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFC1400400)
文摘To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a frequency range of 100 Hz to 10 k Hz and an interval of 100 Hz are used to measure transmission characteristics of channels with lengths of 300 m, 800 m, 1300 m, and 1800 m. The correctness of the fitted channel characteristics by transmitting square wave, composite waves of different frequencies, and ASK modulation are verified. The results show that when the frequency of the signal is below 1500 Hz, the channel has very little effect on the signal. The signal compensated for amplitude and phase at the receiver is not as good as the uncompensated signal.Alternatively, when the signal frequency is above 1500 Hz, the channel distorts the signal. The quality of signal compensated for amplitude and phase at receiver is better than that of the uncompensated signal. Thus, we can select the appropriate frequency for XCTD system and the appropriate way to process the received signals. Signals below1500 Hz can be directly used at the receiving end. Signals above 1500 Hz are used after amplitude and phase compensation at the receiving end.
文摘The crystal structure,magnetic and electrical properties of Bi(0.96)Pb(0.04) FeO3 and Bi(0.92)Pb(0.04)RE(0.04)FeO3(RE=La,Sm,Dy and Yb)polycrystalline samples were prepared by the flash autocombustion technique.X-ray diffraction(XRD)measurements show that the rare-earth doped compositions crystallized in rhombohedral symmetry of space group R3 c.The undoped sample consisted needle shape particles while rare earth substitution preferred platelet like particles as clarified from high resolution transmission electron microscopy(HRTEM).Morphological features were examined using field emission scanning electron microscopy(FESEM).Magnetization measurements showed that Yb^3+ samples possessed the highest room temperature saturation magnetization while when Bi^3+ ions were substituted by La^3+ ions,a smaller MS(0.28 emu/g)was obtained.The coexistence of ferroelectric and magnetic transitions was detected using DSC and χM,indicating the multiferroic characteristics of Bi(0.92)Pb(0.04)RE(0.04)FeO3 crystallites.The Néel temperature shifted upwards with decreasing the ionic radius of rare earth ion.Nice correlation was established between microstructure,morphology and magnetic properties in view of the contribution of magnetocrystalline and shape anisotropy in the magnetic parameters values.
基金supported by the National Natural Science Foundation of China(Nos.51827807,51972191,and 52130602).
文摘Understanding the substrate and temperature effect on thermal transport properties of transition metal dichalcogenides(TMDs)monolayers are crucial for their future applications.Herein,a dual-wavelength flash Raman(DF-Raman)method is used to measure the thermal conductivity of monolayer WS_(2) at a temperature range of 200–400 K.High measurement accuracy can be guaranteed in this method since the influence of both the laser absorption coefficient and temperature-Raman coefficient can be eliminated through normalization.The room-temperature thermal conductivity of suspended and supported WS_(2) are 28.5±2.1(30.3±2.0)and 15.4±1.9(16.9±2.1)W/(m·K),respectively,with a~50%reduction due to substrate effect.Molecular dynamics(MD)simulations reveal that the suppression of acoustic phonons is mainly responsible for the striking reduction.The behaviors of optical phonons are also unambiguously investigated using Raman spectroscopy,and the in-plane optical mode,E(Γ),is surprisingly found to be slightly enhanced while out-of-plane mode,A1g(Γ),is suppressed due to substrate interaction,mutually verified with MD results.Our study provides a solid understanding of the phonon transport behavior of WS_(2) with substrate interaction,which provides guidance for TMDs-based nanodevices.