Ionic Conductivity of Rubidium Iodide Crystals

1973 ◽  
Vol 51 (3) ◽  
pp. 236-240 ◽  
Author(s):  
Suresh Chandra ◽  
John Rolfe
Keyword(s):  
Ionic Conductivity ◽  
Defect Formation ◽  
Formation Enthalpy ◽  
Negative Ion ◽  
Conductivity Measurements ◽  
Transport Parameters ◽  
Vacancy Migration ◽  
Strontium Ions ◽  
Positive Ion ◽  
Migration Enthalpy

The ionic conductivity of pure and strontium-doped rubidium iodide crystals was measured as a function of temperature. Eight transport parameters were calculated from the conductivity results by a nonlinear regression computation. The values obtained for the transport parameters were: Schottky defect formation enthalpy hs = 2.1 eV, entropy ss = 0.5 × 10−3 eV/deg; positive-ion vacancy migration enthalpy Δh1 = 0.60 eV, entropy Δs1 = 0.14 × 10−3 eV/deg; negative-ion vacancy migration enthalpy Δh2 = 1.6 eV, entropy Δs2 = 0.13 × 10−3 eV/deg; association enthalpy of strontium ions and positive-ion vacancies χ = 0.58 eV, entropy η = 0.22 × 10−3 eV/deg. Rubidium carbonate was found to have a negligible solid solubility in rubidium iodide, so that conductivity measurements could not be made on anion-doped crystals. The negative-ion vacancy migration parameters are thus not as accurately determined as the other transport parameters.

Ionic Conductivity of Potassium Bromide Crystals

1971 ◽  
Vol 49 (16) ◽  
pp. 2098-2105 ◽  
Author(s):  
Suresh Chandra ◽  
John Rolfe
Keyword(s):  
Defect Formation ◽  
Formation Enthalpy ◽  
Potassium Bromide ◽  
Negative Ion ◽  
Coulomb Interactions ◽  
Transport Parameters ◽  
Vacancy Migration ◽  
Charged Defects ◽  
Positive Ion ◽  
Migration Enthalpy

The electrical conductivity of single crystals of potassium bromide was measured as a function of temperature, and as a function of the concentration of calcium bromide or potassium carbonate impurity. The results were analyzed on the assumption that the observed conductivity was due entirely to the motion of separated anion and cation vacancies (Schottky defects), with Coulomb interactions between charged defects. Agreement between measured and calculated conductivities at all temperatures showed that this assumption was reasonable. The values obtained for transport parameters were: Schottky-defect formation enthalpy hs = 2.53 eV, entropy Ss = 10.3k; positive ion vacancy migration enthalpy Δh1 = 0.65 eV, entropy Δs1 = 1.89k; negative ion vacancy migration enthalpy Δh2 = 1.22 eV, entropy Δs2 = 7.30k; association of calcium ions and positive ion vacancies enthalpy x = 0.61 eV, entropy η = 2.23k, where k is Boltzmann's constant.

Ionic conductivity of potassium iodide crystals

1970 ◽  
Vol 48 (4) ◽  
pp. 397-411 ◽  
Author(s):  
Suresh Chandra ◽  
John Rolfe
Keyword(s):  
Coulomb Interaction ◽  
Defect Formation ◽  
Formation Enthalpy ◽  
Negative Ion ◽  
Appreciable Effect ◽  
Transport Parameters ◽  
Intrinsic Conductivity ◽  
Vacancy Migration ◽  
Positive Ion ◽  
Migration Enthalpy

The electrical conductivity of pure KI, KI + SrI2, and KI + K2CO3 single crystals was measured as a function of temperature. A method for calculating ionic transport parameters from these results was developed, assuming that the conductivity was due entirely to the motion of positive and negative ion vacancies, and including the effect of association and Coulomb interaction between oppositely charged defects. It was shown that the Coulomb interaction had an appreciable effect on the high-temperature intrinsic conductivity, and the extrinsic conductivity of heavily doped crystals. Calculation of transport parameters from intrinsic-conductivity measurements alone gave erroneous results. From the agreement (within experimental error) between the experimental and calculated results, it was concluded that the only defects taking part in the conduction process were Schottky defects. The following parameters were calculated: Schottky-defect formation enthalpy hs = 2.21 eV, entropy ss = 0.765 × 10−3 eV/deg; positive ion vacancy migration enthalpy Δh1 = 0.63 eV, entropy Δs1 = 0.136 × 10−3 eV/deg; negative ion vacancy migration enthalpy Δh2 = 1.29 eV, entropy Δs2 = 0.805 × 10−3 eV/deg; association of divalent cations and positive ion vacancies enthalpy χ = 0.54 eV, entropy η = 0.190 × 10−3 eV/deg.

Ionic conductivity of potassium chloride crystals

1970 ◽  
Vol 48 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Suresh Chandra ◽  
John Rolfe
Keyword(s):  
Potassium Chloride ◽  
Defect Formation ◽  
Divalent Cations ◽  
Formation Enthalpy ◽  
Negative Ion ◽  
Strontium Chloride ◽  
Coulomb Interactions ◽  
Vacancy Migration ◽  
Positive Ion ◽  
Migration Enthalpy

The electrical conductivity of single crystals of potassium chloride was measured as a function of temperature, and as a function of the amount of strontium chloride or potassium carbonate impurity. The results were analyzed by using a least-squares curve-fitting computer program in which the basic assumption was that conductivity was due entirely to the motion of separated anion and cation vacancies (Schottky defects). Coulomb interactions between charged defects were allowed for by using Debye–Hückel theory. With the exception of the conductivity of pure crystals very near the melting point, experimental conductivity measurements agreed with values calculated from the following parameters: Schottky-defect formation enthalpy hs = 2.59 eV, entropy ss = 9.61k; positive ion vacancy migration enthalpy Δh1 = 0.73 eV, entropy Δs1 = 2.70k; negative ion vacancy migration enthalpy Δh2 = 0.99 eV, entropy Δs2 = 4.14k; association of divalent cations and positive ion vacancies enthalpy χ = 0.58 eV, entropy η = 1.30k.

IONIC CONDUCTIVITY OF POTASSIUM BROMIDE CRYSTALS

1964 ◽  
Vol 42 (11) ◽  
pp. 2195-2216 ◽  
Author(s):  
J. Rolfe
Keyword(s):  
Ionic Conductivity ◽  
Single Crystals ◽  
High Temperatures ◽  
Potassium Carbonate ◽  
Calcium Ions ◽  
Transport Number ◽  
Potassium Bromide ◽  
Negative Ion ◽  
Conductivity Measurements ◽  
Positive Ion

The conductivity of single crystals of potassium bromide has been measured as a function of temperature. Potassium carbonate was found to be sufficiently soluble at high temperatures in KBr to cause a conductivity due to negative ion vacancies. The ionic conductivity parameters of KBr were calculated from conductivity measurements on crystals containing known concentrations of potassium carbonate and calcium bromide without recourse to transport number experiments. A simple theory of association was found to be adequate to describe the interaction between calcium ions and positive ion vacancies. The solubility of free divalent impurities in KBr was also calculated from conductivity measurements. The following enthalpy values were found: for formation of a pair of Schottky vacancies, 2.53 eV; for the motion of positive ion vacancies, 0.665 eV; for the motion of negative ion vacancies, 0.87 eV; for the association of calcium ions and positive ion vacancies, 0.46 eV.

Characterization of New Ionically Conducting Peo-Based Networks by Diffusion, Elasticity Modulus and Ionic Conductivity Measurements

1992 ◽  
Vol 293 ◽  
Author(s):  
Herve Cheradame ◽  
F. Desbat ◽  
P. Mercier-Niddam ◽  
S. Boileau
Keyword(s):  
Diffusion Coefficient ◽  
Ionic Conductivity ◽  
Elasticity Modulus ◽  
Sol Gel ◽  
Cation Transport ◽  
Lithium Cation ◽  
Conductivity Measurements ◽  
Conducting Materials ◽  
Diffusion Studies

AbstractIonically conducting materials containing PEO were prepared from telechelic di(methyl-diethoxy-silane) PEO, synthesized by the hydrosilylation of telechelic diallyl-PEO with methyldiethoxysilane. The network is obtained by the usual sol-gel chemistry. Then, it is filled with LiClO4 by diffusion of the salt and further drying. A comparison is made with the same kind of materials crosslinked using urethane chemistry. Diffusion studies show that the diffusion coefficient of solvent is similar for both types of materials, whilst the ionic conductivity is higher for the networks crosslinked with siloxane bonds. An experiment of diffusion of LiClO4 without solvent showed that this salt has a diffusion coefficient of the order of 2.10-8 cm2.sec-1 at 34°C. The conductivity calculated from this determination is compatible with the mechanism of lithium cation transport by the diffusion of salt molecules. Elasticity modulus measurements show that the salt aggregates are essentially located within the crosslinks at low concentration, but also in the PEO chains for salt concentrations higher than 1 mol/l.

Hg1-xCdxTe: Defect Structure Overview

1990 ◽  
Vol 216 ◽  
Author(s):  
M.A. Berding ◽  
A. Sher ◽  
A.-B. Chen
Keyword(s):  
Point Defects ◽  
Defect Structure ◽  
Defect Formation ◽  
Activation Energies ◽  
Mass Action ◽  
Native Defect ◽  
Native Point Defects ◽  
Vacancy Migration ◽  
Formation Energies ◽  
Diffusion Activation

ABSTRACTNative point defects play an important role in HgCdTe. Here we discuss some of the relevant mass action equations, and use recently calculated defect formation energies to discuss relative defect concentrations. In agreement with experiment, the Hg vacancy is found to be the dominant native defect to accommodate excess tellurium. Preliminary estimates find the Hg antisite and the Hg interstitial to be of comparable densities. Our calculated defect formation energies are also consistent with measured diffusion activation energies, assuming the interstitial and vacancy migration energies are small.

scholarly journals Ionic Conductivity and Phase Transition Behaviour in 4AgI-(1-)-2CuI System

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Mohammed Hassan ◽  
Rfi Rafiuddin
Keyword(s):  
Phase Transition ◽  
Ionic Conductivity ◽  
Binary System ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Conductivity Measurements ◽  
Temperature Dependent ◽  
X Ray ◽  
Dsc Curves ◽  
Transition Behaviour

Samples of general formula 4AgI-(1-)-2CuI, , have been prepared and investigated by XRD, DSC, and temperature-dependent conductivity studies. X-ray diffractograms showed the presence of binary system consisting of AgI and in the sample . Cu-substituted samples showed very similar diffractograms to that of the pure compound which indicates that no effect for the substitution on the nature of the binary system. DSC curves showed the presence of phase transition whose temperature increased with ratio in the system. Ionic conductivity measurements confirmed the occurrence of the phase transition and showed that the high temperature phase is superionic conducting, whose conductivity increases with the increasing amount in the system.

scholarly journals Structural relaxation in AgPO3 glass followed by in situ ionic conductivity measurements

2016 ◽  
Vol 437 ◽  
pp. 43-47 ◽  
Author(s):  
C.B. Bragatto ◽  
D.R. Cassar ◽  
O. Peitl ◽  
J.-L. Souquet ◽  
A.C.M. Rodrigues
Keyword(s):  
Ionic Conductivity ◽  
Structural Relaxation ◽  
Conductivity Measurements

Note on radiationless transitions involving three-body collisions

1936 ◽  
Vol 32 (3) ◽  
pp. 482-485 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Continuous Spectrum ◽  
Negative Ions ◽  
Bound State ◽  
Excess Energy ◽  
Negative Ion ◽  
Positive Ions ◽  
Continuous State ◽  
Direct Formation ◽  
Three Body ◽  
Positive Ion

When an electron makes a transition from a continuous state to a bound state, for example in the case of neutralization of a positive ion or formation of a negative ion, its excess energy must be disposed of in some way. It is usually given off as radiation. In the case of neutralization of positive ions the radiation forms the well-known continuous spectrum. No such spectrum due to the direct formation of negative ions has, however, been observed. This process has been fully discussed in a recent paper by Massey and Smith. It is shown that in this case the spectrum would be difficult to observe.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

Sign in / Sign up

Export Citation Format

Share Document