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Transmission electron microscopy evidence of spontaneous B-cation layered distribution in NaNb(1-x)Ta(x)O3.
- Source :
-
Journal of the American Chemical Society [J Am Chem Soc] 2010 Jul 21; Vol. 132 (28), pp. 9843-9. - Publication Year :
- 2010
-
Abstract
- A transmission electron microscopy (TEM) study of the complex NaNb(1-x)Ta(x)O(3) (0.4 < or = x < or = 0.6) perovskites, combining high-resolution TEM and high-angle annular dark-field scanning TEM, has revealed the formation of extended areas on the crystals where niobium and tantalum order into layers in a 1:1 ratio. NaNb(1-x)Ta(x)O(3) oxides are stoichiometric, and there is neither charge difference nor significant ionic size discrepancy between Nb(V) and Ta(V) cations. As d(0) octahedrally coordinated cations, they show a propensity to second-order Jahn-Teller distortion. This distortion, however, manifests itself to different extents for the two cations and is considered the driving force for the layered ordered distribution observed. The niobium-tantalum segregation we have found can also be interpreted as a naturally occurring nanometer-scale phase separation. Albeit occurring in wide regions of the crystals and not in the entire grains, it shows a clear trend toward a long-range ordered disposition. This is reminiscent of the more general behavior of a recently documented class of perovskites that suffer spontaneous nanoscale phase separation to form a superlattice.
Details
- Language :
- English
- ISSN :
- 1520-5126
- Volume :
- 132
- Issue :
- 28
- Database :
- MEDLINE
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 20578743
- Full Text :
- https://doi.org/10.1021/ja1031858