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Phase transformation mechanism between γ- and θ-alumina
Please use this identifier to cite or link to this item:
http://hdl.handle.net/1860/1816
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| Title: | Phase transformation mechanism between γ- and θ-alumina |
| Authors: | Cai, Shu-Hui
Rashkeev, Sergey N.
Pantelides, Sokrates T.
Sohlberg, Karl |
| Issue Date: | Jun-2003 |
| Publisher: | American Physical Society |
| Citation: | Physical Review B, 67: pp. 224104-1 - 224104-10. |
| Abstract: | y-alumina transforms to θ-alumina and finally to a-alumina in the sequence of thermal dehydration of
boehmite. We report a detailed theoretical investigation of the y- to θ-alumina transformation based on first principles
density-functional calculations. Although the unit cells of cubic y-alumina and monoclinic
θ-alumina look quite different, we have identified cells for both the polytypes (with the composition Al16O24)
that look very similar and can be continuously transformed one to another. The transformation may be described
by a set of aluminum atom migrations between different interstitials while the oxygen atoms remain
fixed. Total-energy calculations along the paths of the atomic migrations have been used to map out possible
transformation pathways. The calculated conversion rate accurately predicts the experimentally measured
transformation temperature. The deduced orientation relationships between the y- and θ-alumina forms also
agree with experimental observations. The formation of several different interfaces observed in domain boundaries
of u-alumina may correspond to different migration paths of the aluminum atoms in neighboring domains
during the y- to θ-alumina phase transition. |
| URI: | http://dx.doi.org/10.1103/PhysRevB.67.224104
http://hdl.handle.net/1860/1816 |
| Appears in Collections: | Faculty Research and Publications (Chemistry)
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