Showing papers on "Ionic conductivity published in 1986"
TL;DR: In this paper, the activation energy of ion transport is independent of the anion, and remains mainly constant at 0.7 eV over the concentration range studied for the ion pair formation.
Abstract: systems have been characterized by x‐ray diffraction and optical microscopy, and the resulting phase diagrams are taken into account for the interpretation of ac impedance measurements. Eutectic reactions and multiple‐intermediate‐compound formation are characteristic of most systems. Simple phenomenological models do not explain the overall conductivity behavior. The activation energy of ion transport is independent of the anion, and remains mainly constant at 0.7 eV over the concentration range studied for . Ion‐pair formation seems to occur at low salt concentration.
408 citations
TL;DR: The linear poly[(alkoxy)phosphazene, [NP(OC 2 H 4 OC 2H 4 OCH 3 ) 2 ] n (MEEP) was synthesized and investigated as a polymeric electrolyte host material as mentioned in this paper.
139 citations
TL;DR: In this paper, the defect structure in 3 mol% Y-TZP was studied by correlated internal friction, dielectric loss, and ionic conductivity experiments, and the relaxation parameters were determined as Hm= 90 ± 3 kJ·mol−1, τ∞= (1.0+1.5−0.6) × 10−14 s for the mechanical relaxation.
Abstract: The defect structure in 3 mol% Y-TZP was studied by correlated internal friction, dielectric loss, and ionic conductivity experiments. A prominent mechanical and dielectric loss peak occurs in the temperature range between 380 and 550 K that depends on the frequency of measurement. The relaxation parameters were determined as Hm= 90 ± 3 kJ·mol−1, τ∞= (1.0+1.5−0.6) × 10−14 s for the mechanical relaxation and Hd= 84 ± 3 kJ·mol−1, τ∞= (1.6+1.7−0.9) × 10–13 s for the dielectric relaxation. The ionic conductivity below 790 K is controlled by an activation enthalpy of Hσ= 89 ± 3 kJ·mol−1; at higher temperatures Hσ= 60 ± 3 kJ·mol–1. An atomistic model is presented which assumes that oxygen vacancies are trapped by yttrium ions forming anisotropic complexes which—by reorientation—cause anelastic and dielectric relaxation. At higher temperatures (>790 K) these complexes are dissociated, which leads to the reduced activation enthalpy for ionic conductivity.
130 citations
TL;DR: In this paper, electrical conductivity and relaxation studies have been carried out on Parel 58 elastomer with a variety of lithium salts in vacuum over the temperature range 5-380 K and at pressures up to 0.65 GPa.
Abstract: Audio frequency electrical conductivity and relaxation studies have been carried out on Parel 58 elastomer and Parel 58 elastomer complexed with a variety of lithium salts. The measurements have been carried out in vacuum over the temperature range 5–380 K and at pressures up to 0.65 GPa over the temperature range 230–380 K. Both the electrical conductivity for the complexed material and the electrical relaxation time associated with the α relaxation in the uncomplexed material exhibit VTF or WLF behavior. From a VTF analysis for both the vacuum electrical relaxation time and electrical conductivity, Ea is found to be about 0.09 eV and T0 is found to be about 40 °C below the ‘‘central’’ glass transition temperature. In addition, it is found that the activation volumes for the electrical relaxation time and the electrical conductivity are the same when compared relative to T0. These results imply that the mechanism controlling ionic conductivity is the same as that for the α relaxation, namely large‐scale segmental motions of the polymer chain.
117 citations
TL;DR: In this article, the relation between the orientational disorder of SiO 4 (PO 4 ) tetrahedra and fast sodium diffusion in superionic NASICON has been studied by conductivity (complex impedance method), DSC, X-ray powder difraction and vibrational spectroscopy (IR and Raman).
116 citations
TL;DR: In this paper, the current-voltage relation and charge distribution in mixed ionic electronic solid conductors (MC) for dc steady state conditions are evaluated for two models: (I) for a MC with a large and uniform ion disorder as, e.g., in δ-Bi2O3, doped CeO2−x, stabilized and reduced ZrO2 or α-AgI and (II) for MC with equal concentrations of quasifree electrons and mobile ions as, i.e., in CeO−x.
103 citations
TL;DR: The room temperature modification of LiZr/sub 2/(PO/sub 4/)/sub 3/ is monoclinic as discussed by the authors, where Li(1) sites are fully occupied, whereas Li(2) ones are empty.
103 citations
TL;DR: In this article, the ionic conductivity of hot-pressed samples of undoped Y 2 O 3 has been studied by the emf-method in atmospheres of controlled oxygen and water-vapor pressures.
100 citations
TL;DR: In this article, the electrical conductivity of sintered specimens of (CeO 2 ) 1− x (CaO) x was investigated by employing a standard four-probe dc technique as a function of temperature between 400°C and 900°C, composition from 0.10⩽ x ⩽0.80, and oxygen partial pressure from 10 −18 to 1 atm.
87 citations
TL;DR: In this article, a binary phase diagram of a mixture of poly(ethylene oxide) and sodium thiocyanate (PEO-NaSCN) is described.
Abstract: Observed phases and transition temperatures in mixtures of poly(ethylene oxide) and sodium thiocyanate (PEO–NaSCN) are described by a binary phase diagram. The components of this system are semicrystalline PEO which can dissolve salt up to a mole fraction Xs=0.023, and a crystalline complex of composition PEO3.5NaSCN (Xcc=0.22). The salt‐deficient PEO component is normally formed by a eutectic reaction with eutectic temperature Te=63 °C. Conductivity of PEO–NaSCN mixtures is calculated assuming that only ions in the amorphous, liquidlike regions contribute to charge transport. This model predicts a positive discontinuity in conductivity on eutectic melting, and a sharp maximum in conductivity at low salt concentrations, in agreement with observed behavior.
84 citations
TL;DR: In this article, a theoretical analysis on yttria-stabilized zirconia obtained in this paper is compared with those obtained in previous work. And the basic assumptions and limitations of the theoretical model are critically examined.
Abstract: Ionic conductivity data of yttria-stabilized zirconia, Y/sub 4/xZr/sub 1-4/xO/sub 2-2x/, reported in the literature as functions of oxygen vacancy concentration, x, and temperature, T, were analyzed according to a theoretical model developed in a previous paper and applied to calcia stabilized zirconia. Because of the different charge-compensation mechanism in yttria stabilized zirconia, Y/sub 4/xZr/sub 1-4/xO/sub 2-2x/, than that in calcia-stabilized zirconia, Ca/sub 2x/Zr/sub 1-2x/O/sub 2-2x/, the theory predicts the occurrence of a maximum of ionic conductivity at an oxygen vacancy concentration, which is just half the oxygen vacancy concentration at the maximum, x = 0.0625 (= 1/16), in calcia-stabilized zirconia. Results of the theoretical analysis on yttria-stabilized zirconia obtained herein are compared with those on calcia-stabilized zirconia obtained in Paper 1 and are also discussed in relation to the ionic conductivity data of the various rare earth oxide-stabilized zirconia systems. The basic assumptions and limitations of the theoretical model are critically examined, and possible modifications of the theoretical model are suggested.
TL;DR: In this paper, the structure-conductivity relationship of network polymers from poly(ethylene oxide) containing lithium perchlorate (LiClO4), in contrast to the polymer complex formed by linear PEO and LiClO 4, was investigated.
Abstract: The structure-conductivity relationships were investigated on the network polymers from poly(ethylene oxide)(PEO) containing lithium perchlorate (LiClO4), in contrast to the polymer complex formed by linear PEO and LiClO4. The crosslinked structure caused a considerable decrease in the degree of the crystallinity of the resulting PEO–LiClO4 complexes, which contributed to high ionic conductivity. Li+ ions were demonstrated as mobile species in these polymer complexes, while ClO4− ions contributed somewhat to ionic conductivity. The high ionic conductivity of the order of 10−5 Scm1 at 30°C was attained by a crosslinked PEO–LiClO4 complex of [LiClO4]/[EO unit] =0.02.
Journal Article•
TL;DR: In this paper, a complex of poly(ethylene oxide) and having the general formula, with have been prepared, and initial transport number measurements indicate that these materials principally conduct anions.
Abstract: Complexes of poly(ethylene oxide) and having the general formula, with have been prepared. These materials are ionic conductors and electronic insulators. The conductivity of is highest, and is comparable to that of above 80°C. DSC analysis and a study of the temperature dependence of their conductivity indicate that these compositions consist of two crystalline phases, corresponding to pure PEO and the salt‐rich complex, and coexisting elastomeric phases. Initial transport number measurements indicate that these materials principally conduct anions.
TL;DR: In this article, solid state galvanic cells are investigated in view of their application for selective and reversible determination of partial pressures of gaseous species which may not be transferred in the solid electrolyte.
TL;DR: In this paper, the electrical conductivity and thermoelectric power of some lithium-titanium ferrites with small amounts of manganese and zinc have been studied as a function of temperature in the range of 300-550 K.
Abstract: The electrical conductivity and thermoelectric power of some lithium–titanium ferrites with small amounts of manganese and zinc have been studied as a function of temperature in the range of 300–550 K and are reported here. The conductivity variation shows two different regions with a large variation in the activation energies. The possible mechanisms with respect to ionic conduction and electron hopping are discussed with the support of thermoelectric power measurements. Lattice parameters are also calculated from x‐ray diffractograms for confirming the single‐phase nature of the ferrites.
TL;DR: In this paper, the computer method of Lattice Statics (HADES/CASCADE) was used to calculate anion migration energies for 30 unique local environments involving the distribution of Y 3+ ions in CeO 2.
TL;DR: In this article, the Li 2 SO 4 -Li 2 CO 3 binary system has been studied using DSC, X-ray diffraction and electrical conductivity measurements, and it has been suggested that high conductivity in the interface region between the finely dispersed crystallites in the eutectic mixture.
TL;DR: In this paper, the ionic conductivity of the ceria-strontia system was investigated as a function of temperature, partial pressure of oxygen, and oxide composition, together with its crystal structure, density and microstructure.
TL;DR: In this article, it is shown that most models cannot explain the broad dielectric loss peaks and the correlation between dieletric loss and dc conductivity, which are both universal features of glass ionic conductivity.
Abstract: It is shown that most models cannot explain the broad dielectric loss peaks and the correlation between dieletric loss and dc conductivity, which are both universal features of glass ionic conductivity. However, these features are reproduced by Stevels' and Taylor's old “random potential energy model” as is shown from a recent approximate solution of the model. It is argued that experimental data should preferably be presented in terms of the frequency-dependent conductivity instead of as dielectric loss.
Patent•
11 Jul 1986
TL;DR: In this paper, a polyether chain with an ionic function was used for the production of electrochemical accumulators. But this was only for the case of polyethers with ionic conduction.
Abstract: Macromolecular material with ionic conduction consists of a salt in solution in a polymer. Said salt comprises an anion which is in the form of a polyether chain of which one end carries an anionic function. Application to the production of electrochemical accumulators.
TL;DR: The ion transport and thermal properties of polymer electrolytes formed by poly(ethylene oxide) (PEO) and lithium perchlorate are discussed in this paper, where regions of existence of amorphous and crystalline phases are defined.
TL;DR: In this article, it was shown that the large entropy of activation is a major source of variation in the magnitude of the conductivity preexponential factor for a wide variety of solid electroytes.
TL;DR: In this paper, the authors investigated the effect of dispersions of Al2O3 and CeO2 on the ionic conductivity of CaF2 in biphasic systems.
TL;DR: In this article, the authors investigated the ion conduction mechanism in network polymers from poly(ethylene oxide) and poly(propylene oxide) containing lithium perchlorate in their amorphous and rubbery state.
TL;DR: In this article, the electrical conductivity of the (AgI) 1 − x (Ag 2 MoO 4 ) x system (x = 0.2, 0.25 and 0.3) was measured in both the liquid and the glassy state.
Abstract: The electrical conductivity of the (AgI) 1 − x (Ag 2 MoO 4 ) x system ( x = 0.2, 0.25, 0.3) was measured in both the liquid and the glassy state. The temperature dependence of the observed dc conductivity in the liquid state is well expressed by the Vogel-Tumman-Fulcher (VTF) equation, while in the glassy state it is described by the Arrhenius law. In particular, an abrupt change in the temperature derivative of the conductivity was found at the glass transition temperature T g . the value of which was independently determined by thermal analysis. The frequency dependence of the conductivity in the glassy state was found only at temperatures far below T g , which may be due to the decrease in the transition rate of conducting Ag + cations. The structural relaxation of glasses appears to yield anomalous behavior of the conductivity near T g , such as deviations from the Arrhenius law, annealing and hysteresis effects.
TL;DR: In this article, a critical review of the literature dealing with inorganic oxide glasses with more than one glass former is presented, and the effects of doping lithium and silver borophosphate glasses with LiCl and AgI, respectively, are investigated.
TL;DR: In this paper, a random walk model for describing mixed alkali effects in ionic conductors of the β-alumina type is proposed. But the model is restricted to the case of a tracer ion.
Abstract: We investigate a random walk model for describing mixed alkali effects in ionic conductors of the β‐alumina type. In our model, the observed drastic variation in the transport properties of the mixed crystals is related to critical properties near a percolation threshold, which originates from the blocking of conduction paths by complexes containing the substituted ions. The motion of a tracer ion and the conductivity are obtained by using the Monte Carlo technique and are discussed in relation to experiments. It is pointed out that anomalous diffusion, which occurs near percolation, leads to a characteristic frequency dependence of the dynamic conductivity, which should be experimentally accessible.
TL;DR: Using impedance spectroscopy, the electrical conductivity of polycrystalline samples of the scheelite oxide BiVO 4 was measured in the temperature range 140-550°C and data for the low temperature regime (140-300°C) interpreted in terms of ionic conductivity due to oxygen ion vacancies as discussed by the authors.
TL;DR: In this paper, the ionic conductivity of (1-x) AgPO3·xMX2 (M = Pb, Hg and X = I, Br, Cl) was measured as a function of temperature from 25°C to Tg.