- Tytuł:
- Disorder and Diffusion in Mayenite
- Autorzy:
-
Boysen, H.
Kaiser-Bischoff, I.
Lerch, M.
Berendts, S.
Hoelzel, M.
Senyshyn, A. - Powiązania:
- https://bibliotekanauki.pl/articles/1550024.pdf
- Data publikacji:
- 2010-01
- Wydawca:
- Polska Akademia Nauk. Instytut Fizyki PAN
- Tematy:
-
61.43.-j
61.66.-f
61.05.fm - Opis:
- Mayenite, $Ca_{12}Al_{14}O_{33}$, has attracted enormous attention for novel technological applications after the discovery of its high oxygen ionic conductivity. The crystal structure consists of a calcium-aluminate framework, comprising 32 of the 33 oxygen anions. The remaining oxygen is distributed over 1/6 of large cages within the framework. The true structure is heavily disordered and usually non-stoichiometric due to the presence of extra anions and is presented for four samples: pure oxygen mayenite (O-mayenite), partly (O/N-mayenite) and fully (N-mayenite) exchanged by nitrogen and doped with iron (Fe-mayenite). All samples were investigated by neutron powder diffraction up to 1050°C. Data were analysed by the Rietveld method and by difference Fourier methods. As prepared O-mayenite contains $O_{2}^{-}$ and $OH^{-}$, N- and O/N-mayenite also $NH_{2}^{-}$, $NH^{2-}$ and $N^{3-}$, while Fe-mayenite was free of extra radicals. In O- and N-mayenite the extra species are lost under vacuum conditions above ca. 700°C, whereas O/N-mayenite retained $NH_{2}^{-}$ up to high temperatures. Diffusion of oxygen proceeds via a jump-like interstitialcy process involving exchange of the "free" oxygen with framework oxygen, coupled to relaxations of Ca ions. In O/N-mayenite $NH_{2}^{-}$ diffuses via interstitial process. In Fe-mayenite encaged oxygen is "invisible" due to extreme delocalisation or loss.
- Źródło:
-
Acta Physica Polonica A; 2010, 117, 1; 38-41
0587-4246
1898-794X - Pojawia się w:
- Acta Physica Polonica A
- Dostawca treści:
- Biblioteka Nauki
Artykuł