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Toward a Unified Approach to the Crystal Chemistry of Aurivillius-Type Compounds.: I. The Structural Model

Abstract A generalized structural model of Aurivillius-type compounds is presented using a 4D superspace group analysis where Aurivillius structures are considered as cation-deficient perovskites with the general formula AB 1− x O 3 . Being essentially composition independent, the model is valid for any Aurivillius-type compounds where x is the only composition-dependent parameter. The atomic domains representing the atoms in superspace are described by means of crenel functions. For any composition, the conventional space groups can be easily derived from a unique superspace group. This work is supported by a TEM investigation where the continuously variable character of the diffraction diagram indicates that the various stacking sequences can be interpreted in terms of a structural modulation over a common average structure.