Showing papers on "Conductivity published in 1971"
TL;DR: In this article, the dielectric constant of saline water was represented by an equation of the Debye form and the parameters for the parameters were given as functions of the water temperature and salinity.
Abstract: The dielectric constant of saline water may be represented by an equation of the Debye form. Equations for the parameters in the Debye expression are given as functions of the water temperature and salinity.
715 citations
TL;DR: In this article, a theory of the a.c. conductivity suitable for hopping conduction in the pseudogap of amorphous semiconductors is developed, and expressions applicable under various conditions are derived.
Abstract: The literature on experiments on a.c. conductivity in various disordered semiconductors is briefly summarized. A theory of the a.c. conductivity, suitable for hopping conduction in the pseudogap of amorphous semiconductors, is developed, and expressions applicable under various conditions are derived. Comparing some of the results with available experimental data, the concentration of localized states in the pseudogap of several materials is estimated.
486 citations
Book•
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01 Jan 1971
TL;DR: In this paper, the International System of Units (SI) fundamental constants conversion factors properties of the elements, conductivities, Radii, Structure Some Crystal Forms Properties of Inorganic Compounds Common Acid-Base Indicators Ionic Properties of Water: Specific Conductivity, Ionic Product Molar Conductivities at Infinite Dilution
Abstract: Periodic Table Electronic Configuration of Elements References to Sources of Chemical Data International System of Units (SI) Fundamental Constants Conversion Factors Properties of the Elements, Conductivities, Radii, Structure Some Crystal Forms Properties of Inorganic Compounds Common Acid-Base Indicators Ionic Properties of Water: Specific Conductivity, Ionic Product Molar Conductivities at Infinite Dilution.
423 citations
TL;DR: In this article, the bulk conductivity of a sheet of colloidal graphite paper with holes randomly punched in it was investigated and the behavior of the conductivity was found to be quite different from that of the percolation probability.
Abstract: We report the results of an experiment to determine the bulk conductivity of a sheet of colloidal graphite paper with holes randomly punched in it. The behavior of the conductivity is found to be quite different from that of the percolation probability.
359 citations
Journal Article•
218 citations
TL;DR: In this article, it was shown that the electrical transport properties of all the three series of rare earth compounds are essentially controlled by the d -electrons of the transition elements which show localized behavior.
201 citations
TL;DR: In this paper, the performance of perovskite-type oxide solid solutions was examined under various conditions to attempt to apply them to the solid electrolyte for high temperature fuel cells operative at 800 ∼ 1000°C.
199 citations
TL;DR: In this paper, the real and imaginary parts of the ac conductivity are shown to increase with frequency according to power law σ=Aωs, where s=0.85 to 0.95, and it is found that the dielectric behavior can be described by a Debye-type relaxation behavior only if a broad distribution of relaxation times exists.
Abstract: Conductivity and dielectric properties of semiconducting glass of composition 80% V2O5:20% P2O5 have been measured as a function of frequency from dc to 3.6 GHz over a temperature range from 77°K to 420°K. A fit of the dc results to a model of polaronic hopping conduction leads to an activation energy due to disorder ΔW=0.09 eV at 77°K and an optical phonon energy of 0.053 eV compared to a calculated Miller‐Abrahams energy of approximately 0.12 eV. The real and imaginary parts of the ac conductivity are shown to increase with frequency according to power law σ=Aωs, where s=0.85 to 0.95, and it is found that the dielectric behavior can be described by a Debye‐type relaxation behavior only if a broad distribution of relaxation times exists. The results are shown to be consistent with a model of ac conduction normally applied to impurity‐doped broad‐band semiconductors, and differences between the temperature dependence of the dc and ac conductivity are attributed to a distribution of site energies in the gl...
158 citations
Patent•
10 May 1971
TL;DR: A REDUCIBLE GAS SENSOR COMPRISING an ELECTROCHEMICAL CELL including a CATHODE, ANODE and an ELECTROLYTE of a rare Earth FLUORIDE is described in this article.
Abstract: A REDUCIBLE GAS SENSOR COMPRISING AN ELECTROCHEMICAL CELL INCLUDING A CATHODE, AN ANODE AND AN ELECTROLYTE OF A RARE EARTH FLUORIDE. THE CELL PROVIDES ANBIENT REDUCIBLE GAS WITH INGRESS TO THE ELECTROLYTE AND THE CONDUCTIVITY OF THE ELECTROLYTE IS ACCORDINGLY MODIFIED, THUS PROVIDING THE CELL WITH A MEASUREABLE CHARACTERISTIC INDICATIVE OF AMBIENTCONCENTRATION OF THE GAS. A RUGGED MINIATURE SENSOR, ADAPTED FOR USE IN PHYSICALLY DISTRUBED ENVIRONMENTS AND PREFERABLY SELF-POWERED, IS FORMED BY THIN FILM DEPOSITION OF THE CELL ELEMENTS.
126 citations
TL;DR: In this article, electrical conductivity and weight change measurements were made on single crystal and polycrystalline nickel oxide as a function of temperature from 900 to 1400°C and oxygen partial pressure from 1 atm to 10 −4 atm.
115 citations
TL;DR: In this article, the behavior of thermally oxidized Al-2O3 films was investigated using the junction logarithmic conductivity characteristic, and the films were shown to exhibit reasonable agreement with the tunneling theory for approximately trapezoidal potential barriers and nonparabolic energy momentum relation in the forbidden band of the insulator.
TL;DR: In this paper, the relationship between the electrically active arsenic, as calculated from the conductivity, and the total arsenic was shown to be consistent with a model of substitutional arsenic atoms being nonionized when in a cluster or in a complex involving one or more vacancies.
Abstract: Large decreases in the conductivity of arsenic‐doped silicon have been observed during 500–970°C heat treatments. The rate of conductivity change depends upon the prior quenching rate from diffusion temperature to room temperature. These conductivity changes are reversed by higher‐temperature treatments. The relationship between the electrically active arsenic, as calculated from the conductivity, and the total arsenic is shown to be consistent with a model of substitutional arsenic atoms being nonionized when in a cluster or in a complex involving one or more vacancies.
TL;DR: The thermal diffusivity of BN has been measured from 100 K-800 K using a 'flash' method; published specific heat data has been used to evaluate the thermal conductivity as discussed by the authors.
Abstract: The thermal diffusivity of BN has been measured from 100 K-800 K using a 'flash' method; published specific heat data has been used to evaluate the thermal conductivity. Over a limited temperature range the results have been confirmed by steady state measurements. The thermal conductivity parallel to the deposition plane has been found to have a maximum value of about 2.5 W cm-1 K-1 at 235 K, while perpendicular to it the thermal conductivity shows no maximum but decreases from about 2.5*10-2 W cm-1 K-1 at 100 K to 1.7*10-2 W cm-1 K-1 at 800 K. The conductivity parallel to the deposition plane has been analysed using a two dimensional mode in which the vibrations in and out of the plane are independent and the latter depend only upon the resistance of the layer to bending. Characteristic temperatures for the two modes of 2290 K and 1200 K respectively have been estimated. Above 200 K the conductivity can be explained in term of Umklapp processes and boundary scattering from crystallites estimated to have average diameters in the deposition plane of 580 AA and 290 AA for the two samples investigated.
TL;DR: The thermal conductivities of three single crystals of BeO have been measured from 2 to 300 K as discussed by the authors, and the maximum conductivity occurs at 45 K where it is 137 W/cm k, and at temperatures below 10 K the conductivity is limited by boundary scattering.
Abstract: The thermal conductivities of three single crystals of BeO have been measured from 2 to 300 K. Phonons carry the heat at all temperatures. At 300 K the conductivity is 3.7 W/cm K, which is slightly less than that of copper. In the purest sample the maximum conductivity occurs at 45 K where it is 137 W/cm k, and at temperatures below 10 K the conductivity is limited by boundary scattering. The anisotropy in the conductivity of this hexagonal material is 20% or less.
TL;DR: In this article, the ionic conductivity of polycrystalline lithium iodide containing 0 to 3% (mole) calcium iodide was studied at temperatures between −30° and 130°C.
Abstract: The ionic conductivity of polycrystalline lithium iodide containing 0 to 3% (mole) calcium iodide was studied at temperatures between −30° and 130°C.The conductivity increased linearly with the concentration of calcium iodide, and it was concluded that the introduction of calcium ions to the lithium iodide crystals induced Schottky defects. The activation energy for the ionic conduction process of agreed well with the value obtained by other investigators. The electronic conductivity of the calcium doped lithium iodide polycrystals was negligible compared to the ionic conductivity.
TL;DR: In this article, Macedo, Bose, and Litovitz described a study of the recently recognized phenomenon of conductivity relaxation in liquid electrolytes as it is observed in the system LiCl+water.
Abstract: This paper describes a study of the recently recognized phenomenon of conductivity relaxation in liquid electrolytes as it is observed in the system LiCl+water. Advantage has been taken of the supercooling ability of 6–20m solutions in this system to reduce solution temperatures to the vicinity of −100°C and thereby to increase the relaxation time characteristic of the conductance process sufficiently to permit its study with conventional ac conductance bridges operating in the frequency range 0.2–2 000 kHz. Extensive data are presented for four solutions in the concentration range 8.3–11.9m. When the frequency‐dependent conductance and capacitance data are analyzed in the dielectric modulus notation developed by Macedo, Bose, and Litovitz, mean relaxation times for conductance are obtained which have a non‐Arrhenius temperature dependence identical to that of the dc conductivity. Earlier studies of dielectric relaxation in these solutions, carried out at room temperature and gigahertz frequencies, are re...
TL;DR: In this paper, a point defect model incorporating five charged and two neutral species was formulated and solved, and the resulting theoretical carrier concentrations agree well in magnitude as well as temperature and oxygen pressure dependence with conductivity measurements on samples of different purities.
TL;DR: In this paper, the effective thermal conductivities of packed beds with stagnant gas were theoretically computed, and it was found that these are expressed as each conductivity was illustrated in graph; (ke)COND is highly pressure dependent,(ke)RAD is slightly pressure dependent and (k)CONTACT is independent of pressure.
TL;DR: In this paper, the temperature variation of ionic conductivity in single crystals of hexagonal silver iodide was studied and analysis of the measurements for conduction both parallel and normal to the c-axis leads to a formation energy for Frenkel defects of 0·60eV.
TL;DR: In this article, the electrical conductivity of single-crystal V2O5 doped with copper (α phase) has been measured along the c axis from 77°K to 298°K.
TL;DR: In this paper, the theory of injecting contacts on insulating solids containing shallow traps is presented, and the types of contact an injecting electrode can make on a high resistivity solid can be divided into three convenient categories: (a) separated accumulation regions, (b) overlapping accumulation regions; and (c) low space charge condition.
TL;DR: The high oxygen pressure conductivity of high-purity single-crystal magnesium oxide at high temperatures varied as the 1/4 power of the oxygen partial pressure with a 3 eV activation energy as mentioned in this paper.
Abstract: The high oxygen pressure conductivity of high-purity single-crystal magnesium oxide at high temperatures varied as the 1/4 power of the oxygen partial pressure with a 3 eV activation energy; the low pressure conductivity varied as the -1/6 power of the pressure with an activation energy of 4 eV. The predominant defects proposed are (1) holes and singly ionized Mg vacancies at high pressure and (2) electrons and doubly ionized oxygen vacancies at low pressures. The effect of impurities was noted. Changes in the grain boundary conductance relative to the crystal conductance of MgO were observed as a function of temperature and pressure, but not as a function of grain boundary orientation, transport direction, or total impurity content. Increased high pressure ionic conductivity in polycrystalline material offered possible evidence for increased grain boundary diffusion.
TL;DR: In this paper, the excess conductivity due to the thermodynamic fluctuations in aluminum films is experimentally investigated and an empirical formula is found on the relation between the pair-breaking parameter δ(0) in the absence of the magnetic field and the normal-state film resistance.
Abstract: The excess conductivity due to the thermodynamic fluctuations in aluminum films is experimentally investigated. The excess conductivity is described by the sum of the Aslamazov-Larkin and the Maki-Thompson terms. An empirical formula is found on the relation between the pair-breaking parameter δ(0) in the absence of the magnetic field and the normal-state film resistanceR N sq as δ(0)=6×10−4R N sq . This formula might be explained in terms of the localized moments and the proximity effect in films. The result of the magnetic field dependence of the pair-breaking parameter revealed that δ(0) cannot be described by an effective magnetic field. The temperature dependence of the excess conductivity at higher temperatures systematically deviates from the theoretical values due to the breakdown of the mean-field theory.
TL;DR: In this article, the porosity correction factor with temperature and pore shape was studied by using the Fricke equation for the thermal conductivity of a two-phase medium containing the second phase as randomly distributed ellipsoids.
TL;DR: In this article, the frequency-dependent conductivity tensor at finite frequencies for a narrow s -band is investigated on the basis of the Hubbard model, and the spectrum of this optical absorption has some characteristic features different from the ordinary absorption due to interband transition.
Abstract: The conductivity tensor at finite frequencies for a narrow s -band is investigated on the basis of the Hubbard model. The frequency-dependent conductivity is expressed in terms of the Fourier transform of a retarded Green function. The Green function is calculated by the use of the equation of motion method. Like Hubbard's first paper, decoupling approximations are made. The obtained frequency-dependent conductivity tensor expresses the optical absorption due to interband transition of electrons between two subbands split by the correlation effect. The spectrum of this optical absorption has some characteristic features different from the ordinary absorption due to interband transition. It is shown that Reσ(ω) has weak singularities like those for forbidden transitions. To demonstrate the result the expression of the conductivity is applied to the one-dimensional cosineband.
TL;DR: The solid solutions V1−xTixO2 (0·02<-x<-0·4) which are monoclinic at room temperature and transform to rutile structures at Tt, H as well as the conductivity jump decrease with increase in x as mentioned in this paper.
TL;DR: In this paper, a review of hydraulic conductivity in woody-stemmed plants is presented and published determinations collated and statistically analysed. But the relationship between the expressions for conductivity and specific or relative conductivity is not clarified, and their relationship established.
Abstract: Hydraulic conductivity in woody-stemmed plants is reviewed and published determinations collated and statistically analysed. Confusion between the expressions for conductivity and specific or relative conductivity are clarified, and their relationship established. Generalizations from the data are examined and attention drawn to systematic errors present in relative conductivity determinations. Estimates of maximum possible stress in water columns of trees are made from published values of relative conductivity and transpiration stream velocity.
TL;DR: In this article, a concentric cylinder conductivity cell with guard heaters was constructed and used to determine the thermal conductivity of polymer melts, which was found to be a linear function of temperature for the melts studied.
Abstract: A concentric cylinder conductivity cell with guard heaters was constructed and used to determine the thermal conductivity of polymer melts. Thermal conductivity was found to be a linear function of temperature for the melts studied, and the thermal conductivity decreased as the complexity of the polymer chain increased. The polymers studied were a linear polyethylene, branched polyethylene, polypropylene, polystyrene, nylon 6, and nylon 6,10. The measurements are precise to within ±6%.
TL;DR: In this article, the effect of Ga, In and Tl on the conductivity, the photoconductivity, and the kinetics of photoconductivities of glassy arsenic selenide was studied.
Abstract: A study has been made of the effect of Ga, In and Tl on the conductivity, the photoconductivity, and the kinetics of photoconductivity of glassy arsenic selenide. It has been shown that as the content of these elements in As2Se3 increases, the conductivity increases, the activation energy decreases, and the spectral response of photoconductivity shifts to the infrared. The magnitude of the drift mobility and its temperature dependence have been determined for all compositions. As shown by a study of the kinetics of photoconductivity, for all glasses, the existence of trapping centres for the majority and minority current carriers in the band gap is typical. Experimental data were used to determine the depth of these centres. Cross-sections for the capture of the electrons and holes by the minority carriers trapping centres have been calculated.