A Cooperative Disorder Model for the Silver Ion Distribution and Flow in the One-Dimensional Ionic Conductor [(CH3)2N(CH2CH2)2O]Ag4I5
✍ Scribed by John S Rutherford
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 295 KB
- Volume
- 140
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A theoretical model shows that the silver ion distribution observed within the iodide tetrahedra of [(CH 3 ) 2 N(CH 2 CH 2 ) 2 O]Ag 4 I 5 is consistent with their disorder being a cooperative effect. The results indicate that the occurrence of silver ions in neighboring tetrahedra is thus eliminated, and the number of second and third neighbor Coulomb interactions is reduced as far as possible, consistent with a minimum Helmholtz energy for the system. The relative permittivity experienced by the silver ions is calculated to be about 50; the resulting low Coulomb interaction between cations in iodide matrices should facilitate their flow. However, in the title compound a bottleneck will occur in the flow of silver ions between adjacent iodide icosahedra unless some are allowed to temporarily occupy higher energy sites and arrangements, and this is the probable cause of the abnormally high activation energy for electrical conduction observed in this compound.