Mixed Conductor
Definition and meaning of Mixed Conductor in chemistry.
A mixed conductor is a material that conducts electrical charge through two or more distinct types of charge carriers, typically both electrons and ions. This dual conductivity is essential in electrochemical devices like solid oxide fuel cells.
In more detail
Mixed conductors simultaneously allow electronic conduction (via electrons or holes) and ionic conduction (via cations or anions) within the same solid material. This property is particularly valuable in fuel cell cathodes, where the material must transport oxygen ions from the electrolyte while also transferring electrons to the external circuit. The relative contributions of electronic and ionic conduction vary with temperature, oxygen partial pressure, and dopant concentration. Mixed conductors enable efficient electrochemical reactions that would be impossible with single-type conductors.
Key facts
| Conducts via | Both electrons and ions simultaneously |
|---|---|
| Primary application | Solid oxide fuel cell cathodes |
| Example material | La1-xSrxMnO3 (lanthanum strontium manganite) |
| Field | Inorganic Chemistry |
Lanthanum strontium manganite (La1-xSrxMnO3) is a widely used mixed conductor in solid oxide fuel cell cathodes, simultaneously conducting oxygen ions and electrons to facilitate oxygen reduction.
Frequently asked questions
Why are mixed conductors better than single-type conductors for fuel cells?
Fuel cell cathodes must transport both ionic charge (oxygen ions) and electronic charge (electrons) simultaneously; a mixed conductor enables this dual function in one material, making efficient electrochemical reactions possible.
What determines the balance between electronic and ionic conduction in a mixed conductor?
The balance depends on material composition, temperature, oxygen partial pressure, and the concentration and mobility of dopants and point defects in the solid.