Conductivity and 'negative U' for ionic grain boundaries
Open Access
- 30 July 1983
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 16 (21) , 4087-4092
- https://doi.org/10.1088/0022-3719/16/21/009
Abstract
The authors show that charge-transfer excitations (like 2M2+ to M++M3+) can be lowered greatly in energy near grain boundaries, where sites are no longer equivalent. In special cases the excitations may be exothermic ('negative-U' behaviour); likely cases include (320) and (122) grain boundaries in FeO. Consequences include effects on conductivity, segregation of impurities with different valence, and on other charge-state-dependent properties.Keywords
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