Showing papers on "Ionic conductivity published in 1971"
TL;DR: The ionic conductivity of the solid electrolyte NaAl11O17 has been measured from − 150 to + 820°C using a novel nonpolarizing solid electrode, reversible to sodium ions as mentioned in this paper.
Abstract: The ionic conductivity of the solid electrolyte NaAl11O17 has been measured from − 150 to + 820°C using a novel nonpolarizing solid electrode, reversible to sodium ions. The resistivity at 25°C was found to be 72 Ω‐cm, the lowest value reported for any ionically conducting oxide ceramic. The enthalpy of motion is 3.79 kcal/mole, and the transport of sodium ions takes place by an interstitialcy mechanism.
288 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 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.
68 citations
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.
57 citations
53 citations
TL;DR: The anodic oxidation of platinum in is studied by using open-circuit transients to determine Tafel slopes and by following film growth optically with an ellipsometer.
Abstract: The anodic oxidation of platinum in is studied by using open‐circuit transients to determine Tafel slopes and by following film growth optically with an ellipsometer. The Tafel slope values are found to be proportional to the film thicknesses measured with the ellipsometer. This result is interpreted in terms of an ionic conduction model in which the overpotential appears across the anodic oxide film, and the logarithm of the ionic current density is proportional to the field in the oxide. The results are compared with the results of similar measurements on iron and tantalum. Although platinum, iron, and tantalum have quite different chemical properties, and their oxides span a thickness range from a monolayer to several thousand angstroms, it is concluded that the same basic process is responsible for the anodic oxidation of the three metals.
53 citations
TL;DR: In this article, the electrical conduction of polyvinyl chloride was measured from low electric field to high field near breakdown below, in, and above a glass transition region, and Ionic conduction was found to hold up to the field near break.
Abstract: The electrical conduction of polyvinyl chloride was measured from low electric field to high field near breakdown below, in, and above a glass transition region. Ionic conduction was found to hold up to the field near breakdown. The estimated jump distance of a charge carrier changes considerably in the glass transition region, while it remains constant (12 A) at a temperature fairly below the glass transition Tg(=87°C) and seems to reach a saturation value (30 A) above Tg. The elongation of substantial jump distance may be explained by the change in the shape and height of potential barriers against ionic migration due to the liberation of micro‐Brownian motion of main chains in the glass transition region.
53 citations
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.
51 citations
TL;DR: In this paper, the ionic conductivity of four relatively pure crystals of potassium chloride has been measured over a wide temperature range, and the defect parameters obtained are used to predict cation and anion diffusion coefficients.
Abstract: The ionic conductivity of four relatively pure crystals of potassium chloride has been measured over a wide temperature range. Precautions were taken to minimize the effects of sublimation at temperatures close to the melting point. The data have been analyzed in terms of the conventional Schottky defect model allowing for transport on both sublattices and for both nearest-neighbor and long-range (Debye-H\"uckel) defect interactions. The defect parameters obtained are used to predict cation and anion diffusion coefficients. The cation diffusion coefficients are in excellent agreement with experiment, but both the enthalpy and entropy of activation for anion diffusion are higher than the values obtained from diffusion experiments by Fuller. Possible reasons for these discrepancies are discussed.
39 citations
TL;DR: The electrical and structural properties of lithium compounds which present predominantly ionic conductivity are reviewed and relationships between structure and electrical properties are, where possible, discussed in this article, where a few results on lithium silico-aluminate glasses are also reported.
Abstract: The electrical and structural properties of lithium compounds which present predominantly ionic conductivity are reviewed and relationships between structure and electrical properties are, where possible, discussed. A few results on lithium silico-aluminate glasses are also reported.
36 citations
TL;DR: In this paper, the authors describe a procedure for maintaining good chemical stability in molten alkali-metal carboxylates, up to about 350 degrees C. Valid physical measurements can be made and the fluids can be used up to this temperature, above which spontaneous decomposition of the anions is difficult to repress.
Abstract: Procedures are described for maintaining good chemical stability in molten alkali-metal carboxylates, up to about 350 degrees C. Valid physical measurements can be made and the fluids can be used up to about this temperature, above which spontaneous decomposition of the anions is difficult to repress. Molten sodium propionate has a useful liquid range of about 60 degrees C and sodium isobutyrate of about 90 degrees C. Sodium n-butyrate transforms into a 'liquid crystal' at about 250 degrees C and into the isotropic liquid at 324 degrees C. For sodium isovalerate corresponding transition points are respectively 188 and 280 degrees C. Thermodynamic measurements are reported of volume and enthalpy changes at transition and melting points. Transport parameters measured include the viscosity and the electrical conductivity. The viscosity of these ionic melts undergoes a steep decrease at the transition from mesomorphic to isotropic liquids. Jumps in ionic conductivity are found both at the melting and clearing points. Even for the isotropic liquids, the ratio of viscosity to electrical conductivity is exceptionally high, compared with the other ionic melts. Mechanisms of melting for these ionic solids are discussed.
TL;DR: In this paper, the effects of catalysts on dielectric properties and D. C. Conduction in poly(ethylene terephthalate) were investigated, and the authors concluded that:
Abstract: Effects of Catalysts on Dielectric Properties and D. C. Conduction in Poly(ethylene terephthalate)
TL;DR: A new type of electrochemical cell, Ag/RbAg/sub 4/I/sub 5//..beta.. Ag/sub 2/Te, RbAg-sub 4-I-sub 5/ and graphite, has been proposed, suitable for appreciable miniaturization and can be used in an electronic circuit as a coulometer or memory device.
Abstract: The ionic conductivities of ..beta.. Ag/sub 2/Te have been determined as a function of the metal-to-nonmetal ratio with the help of the cell Ag/RbAg/sub 4/I/sub 5//..beta.. Ag/sub 2/XrbAg/sub 4/I/sub 5//Ag (X = Se or Te), and the concentrations of the ionic defects at the ideal stoichiometric composition of these compounds have been calculated to be 3.5 * 10/sup 17//cm/sup 3/ for ..beta.. Ag/sub 2/Se at 105/sup 0/C and 9.7 * 10/sup 18//cm/sup 3/ for ..beta.. Ag/sub 2/Te at 97/sup 0/C. The coulometric titrations have been studied with the help of the cell Ag/RbAg/sub 4/I/sub 5//..beta.. Ag/sub 2/X/PT to derive the theoretical equation in order to explain the relation between the cell voltage and the deviation from the ideal stoichiometric composition. Based on these studies, a new type of electrochemical cell, Ag/RbAg/sub 4/I/sub 5//..beta.. Ag/sub 2/Te, RbAg/sub 4/I/sub 5/ and graphite, has been proposed. This cell is suitable for appreciable miniaturization and can be used in an electronic circuit as a coulometer or memory device. 22 references.
TL;DR: In this article, the effect of pigmentation with iron oxide on the type of conduction has been examined in the case of films prepared from a pentaerythritol alkyd, a phenolformaldehyde tung oil and an epoxypolyamide varnish.
Abstract: Ionic conduction in continuous polymer films is of two types. Inverse conduction occurs when the resistance of the film runs counter to, and direct conduction when the resistance follows, that of the external solution. The effect of pigmentation with iron oxide on the type of conduction has been examined in the case of films prepared from a pentaerythritol alkyd, a phenolformaldehyde tung oil and an epoxypolyamide varnish. It was found that upon progressive pigmentation the percentage samples showing direct conduction rose and then fell, furthermore no change in glass transition temperature was observed. It is suggested that this may be due to the segregation of low molecular weight material around the pigment particles thus screening them from the main bulk of the polymer.
Patent•
09 Jul 1971
TL;DR: A solid electrolyte material comprises an alkali metal halide solid electrolytte matrix containing an additive therein for introducing defects into the matrix for increasing the ionic conductivity of the material as mentioned in this paper.
Abstract: A solid electrolyte material comprises an alkali metal halide solid electrolyte matrix containing an additive therein for introducing defects into the matrix for increasing the ionic conductivity of the material.
TL;DR: In this paper, the authors measured the conductivity of pure NaI and NaI+CdI2 and the 22Na+ diffusion as a function of temperature and concluded that the point defects in NaI are of the Schottky type.
Abstract: The conductivity of pure NaI and NaI+CdI2 and the 22Na+ diffusion in pure NaI has been measured as a function of temperature. From a comparison of the diffusion results obtained by the two methods it is concluded that the point defects in NaI are of the Schottky type and that the cation selfdiffusion, which is the dominant contribution to the conductivity, occurs via isolated vacancies. The conductivity results for the Cd2+ doped crystals have been analysed in terms of the simple theory of ionic conductance. This analysis gives values of 2.27 eV, 0.47 eV and 0.51 eV for the enthalpies of Schottky defect formation, cation vacancy migration and Cd2+-cation vacancy association respectively.
TL;DR: In this article, the nuclear magnetic resonance relaxation times T1, T1p, and T2 made on pure and Cd2+ doped single crystals of NaI, over a temperature range 385 to 900 K, are reported.
Abstract: Measurements of the nuclear magnetic resonance relaxation times T1, T1p, and T2 made on pure and Cd2+ doped single crystals of NaI, over a temperature range 385 to 900 K, are reported. The process responsible for relaxation is Na+ selfdiffusion. The cation migration enthalpy is found to be 0.45+or-0.02 eV, and the activation energy for the intrinsic diffusion process is found to be 1.6+or-0.05 eV, in good agreement with ionic conductivity and tracer selfdiffusion studies. An expression for T1p due to dipolar coupling between unlike spins is obtained, and is used to relate the T1p measurements to the sodium ion jump frequency. A comparison of the sodium ion jump frequency obtained from the relaxation time measurements, and from ionic conductivity measurements is made. This indicates that at high temperatures diffusion takes place predominantly via cation single vacancies. At lower temperatures impurity-vacancy complexes contribute to the relaxation indicating that the free and complexed vacancies have similar diffusion rates. At the lowest temperatures impurity precipitation takes place and the total concentration of Cd2+ as a function of temperature is calculated from the T1p measurements, and is in good agreement with that calculated from conductivity studies.
TL;DR: In this paper, the possibility that electrolytic coloration of alkali halides is due to electron injection from an alkali metal cathode, formed by ionic transport taking place in the sample prior to electrolytic colouration, has been investigated.
Abstract: The possibility that electrolytic coloration of alkali halides be due to electron injection from an alkali metal cathode, formed by ionic transport taking place in the sample prior to electrolytic coloration, has been investigated. The following results have been obtained: On heating the samples from room temperature, the coloration starts at a fixed temperature which is a function of the applied voltage. The relation between that temperature and the applied voltage has been discussed on the light of ionic conductivity mechanisms and it appears to be consistent with the formation of a new alkali metal cathode. The cation vacancy migration seems to play the main role in this process. Furthermore, the increase of the electrical current through the sample at the coloration outset can be explained as due to thermoionic emission from an alkali metal cathode.
TL;DR: In this paper, the d.c.d. conductivity of KBr and NaBr crystals, in pure and BaBr2 doped states, has been measured under 70 mmHg bromine gas in the temperature range between 400° and 540°C.
TL;DR: In this article, the a.c. electrical conductivity of single crystals of potassium thiocyanate in various states of purity between 446 K and room temperature was studied.
Abstract: Studies have been made of the a.c. electrical conductivity of single crystals of potassium thiocyanate in various states of purity between 446 K and room temperature. For all samples there was a marked change in the conductivity on passing through the 'phase' transition at 414 K. The position of this break was independent of the purity of the specimens. A complete analysis of the curves was not possible due to the existence of pronounced pretransitional and prefusional effects. On the assumption that Schottky disorder predominates in both phases it is deduced that the enthalpy of cation migration is 0.49+or-0.02 eV in the low temperature phase and 0.74+or-0.02 eV in the high temperature phase. The enthalpy of formation of Schottky pairs is less than 3.2 eV in the low temperature phase and about 1.8 eV in the high temperature phase. A second transition has been detected at 444 K.
Patent•
25 Feb 1971
TL;DR: An ionically conductive organic solid material which is useful for an electrolyte for electric devices is described in this paper, where the material is a crystalline electron donor-acceptor complex comprising 7,7,8,8tetracyanoquinodimethane and a monovalent cation and a small amount of high molecular weight interstitial inclusion impurities.
Abstract: An ionically conductive organic solid material which is useful for an electrolyte for electric devices. The material is a crystalline electron donor-acceptor complex comprising 7,7,8,8tetracyanoquinodimethane and a monovalent cation and a small amount of high molecular weight interstitial inclusion impurities selected from the group consisting of cyanine and triphenylmethane dyes so that the material has an excellent ionic conductivity suitable for an electrolyte.
Patent•
24 Feb 1971
TL;DR: In this article, a method of increasing ionic conductivity of solid electrolytes, such as salts, metal oxides and the like, and an electrochemical galvanic cell utilizing a solid, anhydrous electrolyte which includes a radioactive source for increasing conductivity was discussed.
Abstract: Disclosed is a method of increasing ionic conductivity of solid electrolytes, such as salts, metal oxides and the like, and an electrochemical galvanic cell utilizing a solid, anhydrous electrolyte which includes a radioactive source for increasing conductivity of the solid electrolyte.
01 Jan 1971
TL;DR: In this paper, the effect of aluminosilicates on the properties of dielectrics is investigated in a glassy form and the authors show that the introduction of Al2O3 into alkali silicate glasses is accompanied by a significant increase in the dielectric constant and electrical conductivity.
Abstract: Aluminosilicates in a glassy form are frequently used as materials in the radio and electrical industry and therefore the effect of aluminates on the properties of dielectrics is of interest. The introduction of Al2O3 into alkali silicate glasses is accompanied by a significant increase in the dielectric constant, dielectric loss and electrical conductivity, in contrast to the introduction of borates which leads to a decrease in the conductivity and loss while the dielectric constant is increased [1–6].
01 Jan 1971
TL;DR: In this article, the mechanisms of electrical conduction in single crystal alumina were investigated and an oxygen concentration cell was used to separate the direct current electrical conductivity into its ionic and electronic components over the temperature range 1000-1500°C.
Abstract: The mechanisms of electrical conduction in single crystal alumina were investigated. An oxygen concentration cell was used to separate the direct current electrical conductivity into its ionic and electronic components over the temperature range 1000–1500°C. Transport number and electrical conductivity measurements were made in an oxidizing atmosphere while guarding against both surface and gas phase conduction.
TL;DR: In this paper, the growth of the dendritic structure was controlled by the following factors: 1. Current density and exchange current density2. Ion concentration3. Ionic conductivity.
Abstract: Electrodeposition of metals (such as Ag, Bi, Cd, Co, Cu, Ni, Pb, Pd, Pt, and Zn) from nonaqueous DMF solutions saturated with the corresponding metal salts was investigated under steady-state current with no agitation.Crystals having regular dendritic structure were formed in cases of Co, Ni, Pb, and Zn under current density of 10-64mAmp/cm2. Whereas, less crystalline or amorphous deposits were obtained in case of Pt.The deposits of Bi, Cd, Cu, and Pd were grown up into dendritic or mossy structure, according to the current density.The growth of the dendritic structure was controlled by the following factors:1. Current density and exchange current density2. Ion concentration3. Ionic conductivityThe leading factors for promoting the growth of dendritic structure in D.M.F. solutions were low exchange current density and low ionic conductivity.
01 Jan 1971
TL;DR: Zie et al. as discussed by the authors investigated the B2-BI phase transformation in CsCl and found that the ionic conduction in both phases was studied as a function of temperature in as much detail as possible.
Abstract: This thesis is devoted to three subjects related to the B2—_BI phase transformation in CsCl. i) The ionic conductivity experiments on CsCl up to 1967 did not yield unambiguous results (see section 3.1). Therefore, the ionic conduction in both phases of CsCl was studied as a function of temperature in as much detail as possible. This part of the investigation deals with the properties of cesium choride in the temperature regions outside the transformation region (chapter 3). ii) The influence of addition of CsBr, RbCI of KCI to CsCl on its transition temperature and latent heat has been studied by means of differential thermal analysis (D.T.A.) and ionic conductivity measurements. The purpose was to relate the thermodynamical properties relevant to the temperature induced phase transition in CsCl to those of alkali halides possessing a pressure induced phase change. The study of the CsCI-CsBr system enabled us to make predictions about a possible phase transition in CsBr (Chapter 4). iii) A study of the mechanism of the phase transformation in CsCI, i.e. the kinetics of the process, was carried out because this subject has received too little attention in the literature. Only Gadl et al. [24] (CsCI) and Livshitz et al. [23] (KCI) have reported about kinetic aspects of the B2_BI transition in alkali halides. We have investigated in particular the dependence of the kinetics upon the heating and cooling conditions (chapters 5 and 6). Experimental techniques used include both conductivity and dilatometry measurements. ... Zie: Summary