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Cation segregation in Nb16W18O94 using high angle annular dark field scanning transmission electron microscopy and
1Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, UK. aik10@cam.ac.uk
Journal of Microscopy
|May 10, 2002
Summary
We characterized complex oxide Nb16W18O94 using scanning transmission electron microscopy. Results show preferential segregation of tungsten and niobium cations in specific column sites, indicating non-uniform distribution.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Electron Microscopy
Background:
- Complex oxides exhibit diverse properties influenced by cation distribution.
- Understanding cation ordering is crucial for tailoring material functionalities.
- Scanning Transmission Electron Microscopy (STEM) provides atomic-scale insights.
Purpose of the Study:
- To characterize the cation distribution in Nb16W18O94.
- To investigate the non-uniformity of niobium (Nb) and tungsten (W) cations.
- To develop advanced image processing techniques for complex oxide analysis.
Main Methods:
- High Angle Annular Dark Field (HAADF) imaging in a 200 kV Scanning Transmission Electron Microscope (STEM).
- Development of a novel image processing methodology for analyzing experimental data.
- Projection along the [001] crystallographic direction.
Main Results:
- Demonstrated non-uniform distribution of Nb and W cations within projected cation columns.
- Observed preferential segregation of heavier W cations to specific sites.
- Validated the developed image processing technique for motif localization in distorted fields.
Conclusions:
- The cation arrangement in Nb16W18O94 is not random but exhibits site preference.
- The developed image processing methodology is effective for analyzing complex oxide structures.
- This work advances the understanding of cation ordering in complex oxides and analytical techniques.