A Composite Ionic-Electronic Conductor in the (Ca,Sr,Ba)-Bi Oxide System

ABSTRACTThe rhombohedral alkaline earth-bismuth oxide phase, an oxygen ion conductor, does not coexist stably with electronic conductors in any of the three binary systems, Ca-Bi-O, Sr-Bi-O, Ba-Bi-O. A thermodynamically stable composite of a rhombohedral phase that contains Ba and Sr or Ca or both with the electronic conductor BaBiO3 may be synthesized. The rhombohedral phase appears to have complete mutual miscibility of the alkaline earth elements. The composi- tions of rhombohedral phase that coexist with BaBiO3 in the Sr-Ba-Bi ternary system and the Ca- Sr-Ba-Bi quaternary systems are described. The value of ionic conductivity of the rhombohedral phase (at a constant Bi: [Ca+Sr+Ba]) is not dependent on the relative amounts of Ca, Sr, and Ba. The temperature at which the rhombohedral phase undergoes a polymorphic transformation from a low-temperature (2) form that is a weak ion conductor to a high-temperature (β1) form that is a much better oxygen ion conductor. The temperatures of the polymorphic transformation and of the upper stability limit of the rhombohedral phase both depend strongly on Ca: Sr: Ba. The β1 form develops in the Ba-Bi system at the lowest temperatures and at the highest ones in the Ca- Bi system. On the other hand, the Ca-Bi phase has greater thermal stability than its Ba ana- logues. The temperature range over which a useful composite conductor can operate is, there- fore, strongly dependent upon the bulk composition of the system.

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Transport Properties And Crystal Chemistry Of Ba-Sr-Bi Oxides

MRS Proceedings ◽

10.1557/proc-658-gg4.7 ◽

2000 ◽

Vol 658 ◽

Author(s):

Oya A. Gökçen ◽

James K. Meen ◽

Allan J. Jacobson ◽

Don Elthon

Keyword(s):

Binary Systems ◽

Polymorphic Transition ◽

Conductivity Measurements ◽

Spatial Direction ◽

Ion Conductor ◽

Electronic Conductor ◽

Oxygen Ion ◽

Oxygen Ion Conductor ◽

Conduction Plane ◽

Temperature Ranges

ABSTRACTRhombohedral (R) phases of the binary systems AE-Bi-O (AE = Ca, Sr, Ba) have low temperature (β2) and high temperature (β1) polymorphs and the β1 polymorph is a good oxygen ion conductor. In a previous study, we showed that in the ternary system Ba-Sr-Bi-O, conductivities of polycrystalline R samples are unaffected by Ba:Sr, whereas temperature ranges of the β2↔β1 polymorphic transition are. Recently, we proved that the conductivity of both polycrystalline and single-crystal R samples is sensitive to spatial direction. For single crystals, the conductivity is highest perpendicular to the c-axis. Along the conduction plane, the conductivities are significantly higher than those of polycrystalline R samples; perpendicular to that plane they are significantly lower. The BaBiO3 perovskite (P) phase, predominantly an electronic conductor, has conductivities of 10 to 102 S/cm at 350-800°C in air. Conductivity measurements of the R-P assemblages with different R:P showed that percolation threshold is around 35 volume % P.

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Structure, ionic transport properties and ion dynamics of Ce0.8Y0.2O1.9 oxygen ion conductor: Understanding the impact of sintering temperature

Journal of Solid State Chemistry ◽

10.1016/j.jssc.2021.122451 ◽

2021 ◽

pp. 122451

Author(s):

Sk Anirban ◽

Abhigyan Dutta

Keyword(s):

Transport Properties ◽

Sintering Temperature ◽

Ionic Transport ◽

Ion Dynamics ◽

Ion Conductor ◽

Oxygen Ion ◽

Oxygen Ion Conductor ◽

The Impact

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THERMODYNAMICS AND CATION DIFFUSION IN THE OXYGEN ION CONDUCTOR LSGM

Solid State Ionics ◽

10.1142/9789812702586_0088 ◽

2004 ◽

pp. 787-797 ◽

Cited By ~ 2

Author(s):

M. MARTIN ◽

O. SCHULZ

Keyword(s):

Cation Diffusion ◽

Ion Conductor ◽

Oxygen Ion ◽

Oxygen Ion Conductor

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Recent Advances in Synthesis of Lanthanum Silicate Apatite Powders as New Oxygen-Ion Conductor for IT-SOFCs: A Review

Frontiers in Ceramic Science ◽

10.2174/9781681084312117010008 ◽

2017 ◽

pp. 42-69

Keyword(s):

Ion Conductor ◽

Oxygen Ion ◽

Recent Advances ◽

Oxygen Ion Conductor ◽

Lanthanum Silicate

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Tetragonal zirconia polycrystals — a high performance solid oxygen ion conductor

Solid State Ionics ◽

10.1016/0167-2738(92)90087-6 ◽

1992 ◽

Vol 52 (1-3) ◽

pp. 15-21 ◽

Cited By ~ 40

Author(s):

W WEPPNER

Keyword(s):

High Performance ◽

Tetragonal Zirconia ◽

Ion Conductor ◽

Oxygen Ion ◽

Solid Oxygen ◽

Oxygen Ion Conductor

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Microstructure and Property Study of La2Mo1.5W0.5O9/Ag Composites

Materials Science Forum ◽

10.4028/www.scientific.net/msf.663-665.620 ◽

2010 ◽

Vol 663-665 ◽

pp. 620-624

Author(s):

Chun Li ◽

Da Li ◽

Qian Feng Fang

Keyword(s):

Solid State Reaction Method ◽

Second Phase ◽

Doping Amount ◽

Conventional Solid State Reaction ◽

Single Phase Sample ◽

Ion Conductor ◽

Oxygen Ion ◽

Direct Current Conductivity ◽

Oxygen Ion Conductor ◽

Sample Density

Based on the oxygen ion conductor La2Mo1.5W0.5O9, a series of Ag2O doped samples La2Mo1.5W0.5O9/Ag were prepared with conventional solid-state reaction method. The effects of Ag2O doping on the microstructure and electrical conductivity have been investigated by XRD, FESEM and direct current conductivity measurements. With the increase of Ag2O doping, the grain was further refined and compacted, meanwhile, Ag diffusion distribution in the form of second-phase appear at grain boundary. The sample density and conductivity also gradually increased with the increasing of doping amount. The conductivity of the composite specimen La2Mo1.5W0.5O9 /Ag has a great enhancement when the concentration of Ag2O is around 27 wt%, which is eight times higher than that of the single-phase sample.

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Oxygen Ion Conductivities of Rhombohedral Phases in the Ba-Sr-Bi Oxide System

MRS Proceedings ◽

10.1557/proc-548-499 ◽

1998 ◽

Vol 548 ◽

Cited By ~ 1

Author(s):

O.A. Gökcen ◽

S. Kim ◽

J.K. Meen ◽

D. Elthon ◽

A.J. Jacobson

Keyword(s):

Rhombohedral Phase ◽

Polymorphic Transition ◽

Oxide System ◽

Sudden Increase ◽

Ion Conductor ◽

Temperature Range ◽

Oxygen Ion ◽

Ion Conductivities ◽

Rhombohedral Unit Cell ◽

Impedance Technique

ABSTRACTThe rhombohedral phase of the Ba-Bi-O system is known to be a good oxygen ion conductor. Previous studies on conductivity of that system have shown that there is a sudden increase in conductivity at the β2-β1 polymorphic transition. Therefore, the high temperature β2 phase is a very good anionic conductor with values up to 10−1-100 S/cm. In the Ba-Sr-Bi-O system, the rhombohedral phase that contains Ba and Sr coexists with BaBiO3. Several specimens of the rhombohedral phase with different [Ba]-[Sr] ratios were synthesized. Electron microprobe analysis was used to determine the chemical composition of each specimen and to ensure that it consisted of a monophasic assemblage. Results of X-ray powder diffraction experiments confirmed that each sample has a rhombohedral unit cell. Oxygen ion conductivities of these materials were measured using the 2-probe AC Impedance technique over the 320-730°C temperature range. In each case, a sudden increase in conductivity indicates temperature range of the polymorphic transition. Exchange of the smaller cation Sr for Ba makes the transition temperature increase almost in a linear manner. Conductivities of all β2 polymorphs at a given temperature are very similar to conductivities of Ba-Bi-O and Sr-Bi-O β2 polymorphs. Conductivities of all β1 polymorphs are also similar. Apparently, the nature of the alkaline earth present has only slight influence on conductivities of these phases.

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