Structural studies by high-resolution electron microscopy: intergrowth of ReO₃ and tetragonal tungsten bronze-type structures in the system Nb₂O₅-WO₃

With high-resolution electron microscopy new crystal structures were found in the binary system of Nb₂O₅WO₃ oxides. The compounds are proposed to have the mole ratios 4Nb₂O₅. 22WO₃ and 4Nb₂O₅. 50WO₃. The crystal structures are ascribed to intimate intergrowths of two known structures, the ReO₃ type and tetragonal tungsten bronze type. The latter grows coherently in the host lattice of the former, forming regularly arranged slabs. The coherent intergrowth of the tetragonal tungsten bronze structures is described as the 'rotation operation' on the ReO₃-type structure.