Distributions of charged defects in mixed ionic-electronic conductors. 1: General equations for homogeneous mixed ionic-electronic conductors
- Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering
Mixed ionic-electronic conductors (MIECs) have been widely studied as dense membranes for electrosynthesis (such as partial oxidation of methane and gas separation), as catalytic electrodes for solid-state ionic devices (such as solid oxide fuel cells, batteries, and chemical sensors), and as electrolytes or other components for various devices or systems. General analytical solutions to transport equations are presented for a MIEC subject to various electrical and chemical conditions at the surfaces. The derived general expressions can be used to predict the steady-state distributions of defects and electrical potential within the MIEC as a function of an external stimulus for transport: an electric field, a gradient in chemical potential, or a combination of the two. Also, variations in conductivities, transference numbers, current carried by each type of defect, and chemical potential of oxygen within the MIEC can be readily calculated under different conditions. Analyses indicate that the distribution of mobile defects is approximately linear when the amount of uniformly distributed immobile charges is sufficiently small while the electrical potential distributes nearly linearly when the amount of uniformly distributed immobile charges is sufficiently large. In addition, the derived equations can be used to determine the transport properties of an MIEC from observed steady-state behavior of the MIEC under controlled conditions. Further, and in particular, the derived equations can provide valuable guidance in optimizing performances of devices or systems based on MIECs and in improving or redesigning MIECs for various applications.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States); Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 511957
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 5; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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