Cobalt-doped Ca12Al14O33 mayenite oxide ion conductors: phases, defects, and electrical properties
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Mayenite Ca12Al14O33, as a good oxygen ion conductor with conductivity slightly lower than stabilized ZrO2, has been investigated through doping strategy over the last few decades, but with little success in further improving its oxide ionic conductivity. Here, cobalt-doped Ca12Al14-xCoxO33+δ (0 ≤ x ≤ 1.6) materials were prepared by traditional solid-state reaction method, and then studied by complementary techniques, including X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersion spectrum (EDS) analysis, X-ray photoelectron spectroscopy, and static lattice atomistic simulations. The results showed that these doped materials had much lower Co contents in the crystal structure than their nominal compositions, which was consistent with the high calculated defect formation energy (~ 6.25 eV). The minor divalent Co ions in the crystal structure would reduce the amount of mobile oxide ions and accordingly slightly decreased the bulk conductivities, while most of the Co ions existed in the form of Co2O3 and segregated along grain boundaries in the ceramic samples, which could apparently increase the grain boundary conductions of Ca12Al14O33.
KeywordsOxide ion conductor Ca12Al14O33 mayenite Rietveld refinement Static lattice atomistic simulation
This work was supported by the Guangxi Natural Science Foundation (Nos. 2017GXNSFAA198203, Nos. 2015GXNSFBA139233), National Natural Science Foundation of China (Nos. 21601040), and Guangxi Ministry-Province Jointly-Constructed Cultivation Base for State Key Laboratory of Processing for non-Ferrous Metal and Featured Materials (Nos. 14KF-9).
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Conflict of interest
The authors declare that there are no conflicts of interest.
- 2.Longo S, Cellura M, Guarino F, Ferraro M, Antonucci V, Squadrito G (2017) Life cycle assessment of solid oxide fuel cells and polymer electrolyte membrane fuel cells: a review. In Hydrogen Economy. Academic Press, pp 139–169Google Scholar
- 13.Boysen H, Kaiser-Bischoff I, Lerch M (2008) Anion diffusion processes in O-and N-mayenite investigated by neutron powder diffraction. Diff Fundam 8:2.1–2.8Google Scholar
- 16.Kilo M, Swaroop S, Lerch M (2009) Oxygen uptake and diffusion in mayenite. In defect and diffusion forum. Vol. 289. Trans Tech Publications, pp 511–516Google Scholar
- 23.Coelho A (2007) TOPAS-Academic V4. 1. Coelho Software, BrisbaneGoogle Scholar
- 27.Tosi MP (1964) Cohesion of ionic solids in the Born model. In solid state physics, vol 16. Academic Press, pp 1–120Google Scholar
- 30.Dilks A, Graham SC (1985) Quantitative mineralogical characterization of sandstones by back-scattered electron image analysis. J Sediment Res 55(3):347–355Google Scholar
- 40.Mcdonald JR (1987) Impedance spectroscopy: emphasizing solid materials and systems. Wiley, New York, p 16Google Scholar