The crystal structure of the mixed-layer Aurivillius phase Bi5Ti1.5W1.5O15

The crystal structure of the 1+2 mixed-layer Aurivillius phase Bi5Ti1.5W1.5O15 (SG I2cm no 46: −cba, Z=4, a=5.4092(3)Å, b=5.3843(3)Å and c=41.529(3)Å) consisting of the ordered intergrowth of one and two octahedra thick perovskite-type blocks separated by [Bi2O2]2+ slabs is reported. Supported by an electron diffraction investigation and, using the Rietveld analysis, it is shown that this compound should be described using a I-centering lattice in agreement with the generalised structural model of the Aurivillius type compounds recently presented by the authors. The structure of this Bi5Ti1.5W1.5O15 phase is analyzed in comparison with the related simple members (Bi2WO6 and Bi3Ti1.5W0.5O9). The crystal structure of Bi3Ti1.5W0.5O9 is also reported.