We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Cooperative mechanisms of fast-ion conduction in gallium-based oxides with tetrahedral moieties.
- Authors
Kendrick, Emma; Kendrick, John; Knight, Kevin S.; Islam, M. Saiful; Slater, Peter R.
- Abstract
The need for greater energy efficiency has garnered increasing support for the use of fuel-cell technology, a prime example being the solid-oxide fuel cell. A crucial requirement for such devices is a good ionic (O2− or H+) conductor as the electrolyte. Traditionally, fluorite- and perovskite-type oxides have been targeted, although there is growing interest in alternative structure types for intermediate-temperature (400–700 ∘C) solid-oxide fuel cells. In particular, structures containing tetrahedral moieties, such as La1−xCaxMO4−x/2(M=Ta,Nb,P) (refs 7,8), La1−xBa1+xGaO4−x/2 (refs 9,10) and La9.33+xSi6O26+3x/2 (ref. 11), have been attracting considerable attention recently. However, an atomic-scale understanding of the conduction mechanisms in these systems is still lacking; such mechanistic detail is important for developing strategies for optimizing the conductivity, as well as identifying next-generation materials. In this context, we report a combined experimental and computational modelling study of the La1−xBa1+xGaO4−x/2 system, which exhibits both proton and oxide-ion conduction. Here we show that oxide-ion conduction proceeds via a cooperative ‘cog-wheel’-type process involving the breaking and re-forming of Ga2O7 units, whereas the rate-limiting step for proton conduction is intra-tetrahedron proton transfer. Both mechanisms are unusual for ceramic oxide materials, and similar cooperative processes may be important in related systems containing tetrahedral moieties.
- Subjects
CONDUCTION electrons; IONS; OXIDES; MOIETIES (Chemistry); FUEL cells
- Publication
Nature Materials, 2007, Vol 6, Issue 11, p871
- ISSN
1476-1122
- Publication type
Article
- DOI
10.1038/nmat2039