The Stability of Wüstite by Electromotive Force Measurements on All-Solid Electrolytic Cells

Barbi, G

doi:10.1021/j100792a029

Cited by 20 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results reported by Raccah [6][7][8][9][10], strongly suggest a microphase or domain ordering of the oxygen at low temperatures; the ordering is ultimately randomized by thermal energy at the higher temperatures. Note that the suggested microphase ordering involves the oxygen component, whereas the iron.component, by virtue of the Gibbs-Duhem integrations, appears to exhibit a disordering effect.…”

Section: Discussionmentioning

confidence: 99%

A Thermodynamic Study of the Wuestite Phase.

Ackermann¹,

Sandford²

1966

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

A Thermodynamic Study of the Wuestite Phase.

Ackermann¹,

Sandford²

1966

View full text Add to dashboard Cite

“…10. [15,36,37,41,42,45,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67] and calculated lines. The calculated oxygen isobars are shown by the dashed lines.…”

Section: Phase Diagramsmentioning

confidence: 99%

Thermodynamic reevaluation of the Fe–O system

Hidayat

Shishin

Jak

et al. 2015

Calphad

115

View full text Add to dashboard Cite

“…Several emf measurements (1,3,(5)(6)(7)(8) of oxygen activities and phase boundary composition limits for wfistite exhibit rather poor agreement with each other and do not agree with a recent composite analysis of the Fe-O system by the authors (9). Included in this composite were seven independent studies, using either CO2/CO gas equilibration (10)(11)(12)(13) or galvanic cell (3,8) techniques.…”

mentioning

confidence: 84%

“…The rate of cell drift expected when the electronic conductivity is due primarily to electron conduction (e.g., Fe-FexO reference potentials) was given by Eq. [6]. The exponential dependence of the drift rate with oxygen potential gradient (i.e., E) can give significant rates of transfer even at relatively low cell voltages.…”

Section: Js8 = Ka[exp U --I] + Kcp[l --Exp --U] [I]mentioning

confidence: 99%

“…In the present paper, a critical analysis of galvanic cell techniques, which employ calcia-stabilized-zirconia (CSZ) electrolytes, is given to determine the O/Fe) which has been reported in several emf studies on wfistite (1,6,7). Consideration is given to the manner in which the low-level electronic conduction (hole or electron) present in CSZ causes ceil instabilities due to oxygen permeation through the electrolyte.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Solid‐State Coulometric Titration: Critical Analysis and Application to Wüstite

Giddings¹,

Gordon²

1974

J. Electrochem. Soc.

View full text Add to dashboard Cite

A critical analysis was performed on galvanic cell techniques which employ calcia-stabilized zirconia electrolytes. The presence of low-level electron or hole conduction in the ionic conducting range of the electrolyte was found to be responsible for oxygen permeation through the electrolyte which can either oxidize or reduce a single-phase oxide and, hence, lead to drift in the open-circuit emf with time. Taking oxygen permeation into account quantitatively, a series of isothermal titration experiments in wiistite was performed in which the cell emf was found to be linear with composition (i.e., oxygeniron molal ratio). These results are in excellent agreement with a recent composite analysis of all thermodynamic data in the Fe-O system. Previous cell studies in which deviant behavior has been reported are probably due to improper galvanic cell techniques. No evidence was found to support the existence of more than one-phase or second-order transitions within the wiistite phase.Recently, considerable interest has been generated on the use of solid-state galvanic cells which employ oxide electrolytes (e.g. CaO-ZrO2, Y~O~-ThO~) to study the thermodynamic properties of nonstoichiometric oxide systems. Since voltages may be measured with high precision emf measurements should lead to a direct evaluation of oxygen activities with much greater accuracy than is normally possible with conventional gas equilibration techniques. The precision of measurement in combination with the possibility of coulometric titration, which allows the composition of an oxide to be changed in situ, permits not only a continuous determination of oxygen activity as a function of composition, but also the composition limits of the phase itself. In spite of the potential advantages, the use of oxide electrolytes has not always led to increased accuracy in the measurement of oxygen activities. Several workers (1-4) have reported difficulties in operating cells which were stable with time, thereby necessitating the use of empirical correction factors to determine absolute compositions.Several emf measurements (1, 3, 5-8) of oxygen activities and phase boundary composition limits for wfistite exhibit rather poor agreement with each other and do not agree with a recent composite analysis of the Fe-O system by the authors (9). Included in this composite were seven independent studies, using either CO2/CO gas equilibration (10-13) or galvanic cell (3,8) techniques. The composite possessed the following properties: (i) the partial molal free energy of oxygen (aGo) in wfistite varied linearly with composition (O/Fe) 2 and temperature; a (ii) the partial molal enthalpy (~H--o) and entropy (aSo) of oxygen varied linearly with composition and were independent of temperature. EMF or gravimetric data which deviated from this linear behavior were rejected for experimental reasons (9).In the present paper, a critical analysis of galvanic cell techniques, which employ calcia-stabilized-zirconia (CSZ) electrolytes, is given to determine the cause for nonlinear...

show abstract

The Stability of Wüstite by Electromotive Force Measurements on All-Solid Electrolytic Cells

Cited by 20 publications

References 0 publications

A Thermodynamic Study of the Wuestite Phase.

A Thermodynamic Study of the Wuestite Phase.

Thermodynamic reevaluation of the Fe–O system

Solid‐State Coulometric Titration: Critical Analysis and Application to Wüstite

Contact Info

Product

Resources

About