Figure 1
Atomic structure and schematics of Aurivillius phases with (a) three (m = 3, Bi4Ti3O12) and (b) four perovskite units (m = 4, Na0.5Bi4.5Ti4O15) between two (Bi2O2)2+ interlayers. The three- and four-unit blocks are denoted further on as A and B units. In the schematic representation, the rhomb symbolizes a perovskite unit and a grey rectangle the (Bi2O2)2+interlayer. (c) Cross-sectional HRTEM image of a layer stack which contains both three and four perovskite units.  [article HTML]

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