ISSN:
1432-2021
Keywords:
Key words Hexacelsian
;
Polymorphism
;
Diffuse distribution
;
Dynamical disorder
;
Correlated tetrahedral rotation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
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 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).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002690050007
