Tungsten bronze structure

Figure 4.13 Perovskite tungsten bronze structure (a) idealized structure of W03, composed of comer-linked W06 octahedra and (b) interpolation of large A cations into the cages of the W03 structure generates the perovskite tungsten bronze structures, AxW03.

S.Fabbrici, E.Montanaii, G.Calestani and A. Migliori Charge ordering and tilt modulation in multiferroic KxM"xM "i xF3 (0.4transition metal fluorides with tetragonal tungsten bronze structure Chem. Mater. 2004 16(16) 3007-3019... 

Figure 13 Projections of (a) tetragonal(II), and (b) hexagonal "tungsten bronze" structure. A polyhedral representation showing the large pentagonal and hexagonal tunnels, respectively. From Reference 55.

FIGURE 5.35 (a) The tetragonal tungsten bronze structure (b) the hexagonal tungsten bronze structure. The shaded squares represent WOe octahedra, which are linked to form pentagonal, square and hexagonal tunnels. These are able to contain a variable population of metal atoms, shown as open circles. 

Figure 9.1 Tetragonal tungsten-bronze structure of SiiBai-xNboOf, (Strontium barium nio-bate, SBN). Characteristic are the corner-linked niobium-oxygen-octahedra and 3 types of vacancies A,Bi,2,3 and C. Sr2+-ions are embedded in the A- and B2-positions and Ba2+ in the Bi-positions according to their ionic radii. The C-positions and B3-position remain empty.

M = V. Cr. Fe. Ga. Ti. Nb. or W X = F or F + O x = 0.35—0.55 0 < y < 1) have been obtained by heating mixtures of the corresponding fluorides and oxides. These materials all crystallize with the hexagonal tungsten bronze structure and their lattice constants have been determined.98... 

Fig. 6.16 Projection of the tungsten bronze structure in the c plane. The inset shows the polar directions in orthorhombic PbNb206 =M 0=0 [P.B. Jamieson et al. (1968) J. Chem. Phys. 48, 5048-57],...

A good deal of work is still required to clarify the tetragonal and hexagonal tungsten bronze structures for which only the metal positions are known (32, 34). Superstructures of both have been observed, but little is known about them except in the case of the hexagonal phase at the composition BOs, where they are due to the ordering of molybdenum, an impurity substituent for tungsten (26). 

The conductivity of H—NiF3 is roughly 1 x 10 6(f).cm) 1 in contrast ofR—NiF3 which is an insulator [47], It is assumed that the conductivity associated with H—NiF3 is due to mobility of the K+ ions in the lattice of the hexagonal tungsten bronze structure. 

The preparation under high pressure (65 kbar) of Mo bronzes with tungsten bronze structures has been described for example, cubic Na (Mo03 and K MoOs (x 0-9) and tetragonal K MoOs (x The Mo bronzes prepared by the electrolysis... 

FIGURE 4 12 Tetragonal tungsten bronze structure the circles represent possible metal atom sites and the shaded squares WOs octahedra [4.30]. 

FIGURE 4.14. Intergrowth tungsten bronze structure of the pyrochlore type (single tunnel) [4.30],... 

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