Structural studies by electron microscopy: coherent intergrowth of the ReO₃ and tetragonal tungsten bronze structure types in the system Nb₂O₅-WO₃

High-resolution lattice images from WO₃-rich compositions in the system Nb₂O₅-WO₃ contain direct evidence for the coherent intergrowth of extensive domains of several orientations of the ReO₃-type structure with the more complex tetragonal tungsten bronze-type structure. A model for the transformation between the two structure types is proposed.