Tungsten bronze type crystals

When 0.4 < x < 0.53, an orthorhombic phase is observed in the AgxNb02+xFi.x system. This phase undergoes a phase transition at 900°C that leads to the formation of a tetragonal phase, which crystallizes in a tetragonal tungsten bronze-type structure with cell parameters a = 12.343 and c = 3.905 A. When 0.82 < x < 1, solid solutions based on AgNb03 were found, which crystallize in a perovskite-type structure. 

LiNbC>3 type crystals and compounds that crystallize in a tungsten bronze-type structure. 

Strontium barium niobate is a single-crystal material with the tungsten bronze type of structure which is made by the Czochralski method but has yet to find a major use. It has relaxor characteristics of the type shown in Fig. 7.1 which give it a high pyroelectric coefficient and detectivity, but its high permittivity lowers the figure of merit l. ... 

Figure 31 (a) Electron micrograph of a crystal of an intergrowth tungsten bronze phase in the K.WOa system. The structure consists of slabs of WOs-like structure five octahedra wide separated by strips of the hexagonal tungsten bronze type, (b) A drawing of the idealized structure of the crystal in (a)... 

Tungsten Bronze-Type Family Ba2NaNb 0i (BNN) (LB Ni/mhcr 66-o7j. This crystal is ferroelectric below about 580 °C. The crystal structure is modulated below 300 °C. This material is utilized for optical second-harmonic generation and in optical parametric osdllators (Fig. 4.5-38). 

M. Leblanc, G. Ferey, P. Chevallier, Y. Calage, R. De Pape, Hexagonal tungsten bronze-type Fe" fluoride - (H20)o.33FeF3 - crystal-structure, magnetic-properties, dehydration to a new form of iron trifluoride, J. Solid State Chem., 47, 53-58 (1983). 

When the B atom sites of perovskites are occupied by atoms of different valences (as in BajUOg) the structure is distorted but with retention of cubic symmetry here the oxygens are closer to U than to Ba. The tungsten bronzes, Na WOj, also crystallize in the perovskite structure when 0.32 < x < 0.93 Na MoOj- and K Mo03-type systems (where 0.9 < x < 0.97) are also perovskites. In these bronzes not all the A sites are fliled. 

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