The Crystal Structure of Nb2WO8.

Structural studies by electron microscopy: coherent intergrowth of the ReO3and tetragonal tungsten bronze structure types in the system Nb2O5–WO3

“…As the WO3 content of the product increases, so will the size of the component blocks, until finally the NbzOs-type of structure loses stability, and transformation to WNbzOs occurs. The structure of the latter (Lundberg, 1972) is closely related to that of LiNb6OlsF (Lundberg, 1965), which as Hyde & O'Keeffe (1973) have shown, can be readily derived from the ReOs structure by the periodic application of the rotation operation illustrated in Fig. 6.…”

Na7Nb15W13O80 – A new type of tunnel structure studied by X-ray diffraction and HREM techniques

“…All M atoms are displaced from z = 0, just as in Nb2WO 8 (Lundberg, 1972). On the other hand, the O atoms are less than 3a from z = 0 or z = ½ (see Table 1).…”

“…From high-resolution electron-microscopy (HREM) images recorded with the Siemens microscope it was inferred that the title compound contains structural elements of the type found in LiNb60~5 F (Lundberg, 1965), Nb2WO s (Lundberg, 1972) and NaNb60~5 F (Andersson, 1965). This assumption was supported by the fact that the b axis is, within less than 1%, equal to twice the distance between two pentagonal columns (PC's) joined via a triangular link in these three compounds (for nomenclature see Lundberg, Sundberg & Magn~li, 1982).…”

“…In this way tunnels are formed which are S-shaped in cross section and in which the Na atoms reside. The star-shaped clusters of polyhedra are stacked on top of each other forming pentagonal columns (Lundberg, 1971) running parallel to the c axis. Likewise, the bridging octahedra share corners to form strings running in the same direction.…”

Quaternary Lead–Niobium–Tungsten Oxides Based on the Tetragonal Tungsten Bronze Structure

“…Since PTs and PCs can be arranged in many ways, preparations of this type are typically disordered (14}16). However, at certain compositions ordered structures exist, such as Nb W O (17), Nb W O (18,19), and Nb WO (20). Of these only Nb W O (henceforth referred to as 3-TTB) is based entirely on a TTB framework, possessing a simple three-fold superstructure where 4 out of 12 empty PTs are "lled to produce PCs, as shown in Fig.…”