Design of solid electrolytes for use with dissimilar gas electrodes

Mukhopadhyay, Sukanya; Jacob, Κ. T.

doi:10.1016/0022-0728(95)04103-u

Cited by 6 publications

(5 citation statements)

References 21 publications

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“…Both experiment and theoretical analysis show that the chemical potentials of the neutral form of the mobile species at the electrodes determine the EMF of a cell that incorporates a composition-graded electrolyte, when there is only one mobile ion with transport number close to unity. [29][30][31][32][33] Measurable diffusion potential is not generated by the concentration gradient of relatively immobile ions. The uncertainty limit represents two times the standard deviation.…”

Section: Resultsmentioning

confidence: 99%

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Jacob

Panwar

Gupta

et al. 2014

J. Electrochem. Soc.

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Innovative bi–electrolyte solid-state cells incorporating single crystal CaF2 and composition-graded solid electrolyte (LaF3)y·(CaF2)1-y (y = 0 to 0.32) were used for measurement of the standard Gibbs energy of formation of hexagonal La0.885Al11.782O19 and cubic LaAlO3 from component binary oxides La2O3 and α-Al2O3 in the temperature range from 875 to 1175 K. The cells were designed based on experimentally verified relevant phase relations in the systems La2O3–Al2O3–LaF3 and CaF2–LaF3. The results can be summarized as: 5.891 α-Al2O3 + 0.4425 La2O3 (A-rare earth) → La0.885Al11.782O19 (hex), ΔGof(ox)( ± 2005)/J mol− 1 = −80982 + 7.313(T/K); 1/2 La2O3 (A-rare earth) + 1/2 α-Al2O3 → LaAlO3 (cubic), ΔGof(ox)( ± 2100)/J mol− 1 = −59810 + 4.51(T/K). Electron probe microanalysis was used to ascertain the non-stoichiometric range of the hexaaluminate phase. The results are critically analyzed in the light of earlier electrochemical measurements. Several imperfections in the electrochemical cells used by former investigators are identified. Data obtained in the study for LaAlO3 are consistent with calorimetric enthalpy of formation and entropy derived from heat capacity data. Estimated are the standard entropy and the standard enthalpy of formation from elements of hexagonal La0.885Al11.782O19 and rhombohedral LaAlO3 at 298.15 K.

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Section: Resultsmentioning

confidence: 99%

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Jacob

Panwar

Gupta

et al. 2014

J. Electrochem. Soc.

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“…10 It has been shown both by experiment and theoretical analysis that the EMF of a cell that incorporates a composition-graded electrolyte is determined by the chemical potentials of the neutral form of the mobile species at the electrodes, when there is only one mobile ion with transport number close to unity. [14][15][16][17][18] The concentration gradient of relatively immobile ions does not result in a diffusion potential. [14][15][16][17][18]…”

Section: A Interpretation Of the Emf Of The Solid-state Cellmentioning

confidence: 99%

“…[14][15][16][17][18] The concentration gradient of relatively immobile ions does not result in a diffusion potential. [14][15][16][17][18]…”

Section: A Interpretation Of the Emf Of The Solid-state Cellmentioning

confidence: 99%

Measurement of Gibbs energy of formation of LaGaO₃ using a composition-graded solid electrolyte

Jacob

Dasgupta

Näfe³

et al. 2000

J. Mater. Res.

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A composition-graded solid electrolyte (LaF3)y · (CaF2)1-y was used for the measurement of the standard Gibbs energy of formation of LaGaO3 from its component oxides. An equimolar mixture of CaO and CaF2 was employed as the reference electrode. The composition of the working electrode depended on temperature. A three-phase mixture of LaGaO3 + Ga2O3 + LaF3 was used in the temperature range from 910 to 1010 K, while a mixture of LaGaO3 + Ga2O3 + LaO1-xF1+2x was employed from 1010 to 1170 K. Both the reference and working electrodes were placed under pure oxygen gas. Because of the high activity of LaF3 at the working electrode, there was significant diffusion of LaF3 into CaF2. The composition-graded electrolyte was designed to minimize the electrode–electrolyte interaction. The concentration of LaF3 varied across the solid electrolyte; from y = 0 near the reference electrode to a maximum value y = 0.32 at the working electrode. For the correct interpretation of the electromotive force at T > 1010 K, it was necessary to use thermodynamic properties of the lanthanum oxyfluoride solid solution. The standard Gibbs energy of formation of LaGaO3 from its component oxides according to the reaction, ½La2O3 (A-rare earth) + ½Ga2O3 (b) → LaGaO3 (rhombohedral) can be represented by the equation: δGo f,(ox) /J mol -1 = –46 230 + 7.75 T/K (±1500).

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“…It has been demonstrated in an earlier study that the EMF of a cell incorporating the composition‐graded solid electrolyte La y Ca 1− y F 2− y obeys the Nernst equation. Both experiment and theoretical analysis show that the chemical potentials of the neutral form of the mobile species at the electrodes determine the EMF of a cell that incorporates a composition‐graded electrolyte, when there is only one mobile ion with transport number close to unity . Measurable diffusion potential is not generated by the concentration gradient of relatively immobile ions.…”

Section: Resultsmentioning

confidence: 99%

“…Both experiment and theoretical analysis show that the chemical potentials of the neutral form of the mobile species at the electrodes determine the EMF of a cell that incorporates a compositiongraded electrolyte, when there is only one mobile ion with transport number close to unity. [29][30][31][32][33] Measurable diffusion potential is not generated by the concentration gradient of relatively immobile ions.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Determination of Gibbs Energy of Formation of LaCrO₃ Using a Composition‐Graded Bielectrolyte

2013

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Presented are new measurements of the standard Gibbs free energy of formation of rhombohedral LaCrO3 from component oxides La2O3 and Cr2O3 in the temperature range from 875 to 1175 K, using a bielectrolyte solid‐state cell incorporating single crystal CaF2 and composition‐graded solid electrolyte (LaF3)y·(CaF2)1−y (y = 0–0.32). The results can be represented analytically as ΔGf(ox) O (±2270)/J·mol−1 = −72329 + 4.932 (T/K). The measurements were undertaken to resolve serious discrepancies in the data reported in the literature. A critical analysis of previous electrochemical measurements indicates several deficiencies that have been rectified in this study. The enthalpy of formation obtained in this study is consistent with calorimetric data. The standard enthalpy of formation of orthorhombic LaCrO3 from elements at 298.15 K computed from the results of this study is ΔHf(298.15) O/kJ·mol−1 = −1536.2 (±7). The standard entropy of orthorhombic LaCrO3 at 298.15 K is estimated as 99.0 (±4.5) J·(mol·K)−1.

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Design of solid electrolytes for use with dissimilar gas electrodes

Cited by 6 publications

References 21 publications

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Measurement of Gibbs energy of formation of LaGaO₃ using a composition-graded solid electrolyte

Electrochemical Determination of Gibbs Energy of Formation of LaCrO₃ Using a Composition‐Graded Bielectrolyte

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Design of solid electrolytes for use with dissimilar gas electrodes

Cited by 6 publications

References 21 publications

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Use of Composition-Graded Bi-Electrolyte Cells for Thermodynamic Studies on Lanthanum Aluminates

Measurement of Gibbs energy of formation of LaGaO3 using a composition-graded solid electrolyte

Electrochemical Determination of Gibbs Energy of Formation of LaCrO3 Using a Composition‐Graded Bielectrolyte

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Measurement of Gibbs energy of formation of LaGaO₃ using a composition-graded solid electrolyte

Electrochemical Determination of Gibbs Energy of Formation of LaCrO₃ Using a Composition‐Graded Bielectrolyte