How to interpret Onsager cross terms in mixed ionic electronic conductors.

Area of Science:

• Materials Science
• Physical Chemistry
• Solid-State Physics

Background:

• Mixed ionic electronic conductors (MIEC) are crucial materials for electrochemical devices.
• Understanding transport phenomena in MIECs is essential for optimizing device performance.
• Onsager cross transport coefficients have been used to describe coupled transport processes.

Purpose of the Study:

• To re-examine the interpretation of Onsager cross transport coefficients in MIEC oxides.
• To determine if cross terms are fundamental or artifacts in MIEC transport measurements.
• To develop a more accurate model for transport phenomena in MIECs.

Main Methods:

• Analysis of Onsager cross transport coefficients.
• Development and application of a comprehensive defect model for MIEC oxides.
• Theoretical examination of transport mechanisms in MIECs.

Main Results:

• Demonstration that Onsager cross terms are artifacts of measurement analysis.
• Identification of an appropriate, comprehensive defect model for MIECs.
• Elimination of the necessity for cross terms when using the comprehensive defect model.

Conclusions:

• The interpretation of Onsager cross transport coefficients in MIECs requires reevaluation.
• Cross terms in MIEC transport measurements are analytical artifacts, not intrinsic properties.
• A comprehensive defect model provides a more accurate description of transport in MIECs without cross terms.