Abstract
The results of a temperature-dependent electron diffraction study of the low frequency modes of distortion of Ba-hexacelsian and their relationship to the α-β polymorphic phase transition therein are presented. Cs- and Rb-doped Ba-hexacelsian specimens are also investigated. An extremely strong and characteristic diffuse intensity distribution in the form of polarized sheets of diffuse intensity perpendicular to the <1 1 0> directions is found for the high temperature polymorph and the doped specimens. The diffuse distribution appears pears to result from coupled tetrahedral rotation of <1 1 0> columns of corner-connected (Al,Si)O4 tetrahedra about the [0 0 1] axis (uncorrelated from column to column as a result of the positioning of the rotation axes).
| Original language | English |
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| Pages (from-to) | 194-202 |
| Number of pages | 9 |
| Journal | Physics and Chemistry of Minerals |
| Volume | 27 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Feb 2000 |