Tungsten and molybdenum bronzes

Tungsten and molybdenum bronzes, AxW03 and AxMo03 (As k, Rb, Cs) are generally prepared by reaction of the alkali metals with the host oxide. Electrochemical methods are also employed for these preparations. A novel reaction that has been employed to prepare bronzes which are otherwise difficult to obtain involves the reaction of oxide host with anhydrous alkali iodides [49] ... 

Investigations of mobility of protonic species have concentrated primarily on tungsten and molybdenum bronzes. In the case of hydrogen oxide bronzes, apparent inconsistencies can arise in comparing studies of materials prepared chemically (Zn/Ha(aq)) and materials prepared by hydrogen spillover (H2(g)/Pt-catalyst). In phases in which H is present... 

J. Gabel, W. Vonau, P. Shuk, and U. Guth, New reference electrodes based on tungsten-substituted molybdenum bronzes. Solid State Ionics 169, 75-80 (2004). 

Special mention must be given to the numerous studies concerning hydrogen bronze formation induced by spillover. In particular, tungsten and molybdenum oxide hydrogen bronzes have been thoroughly studied since Khoobiar s experiments (4). 

Oxides of the type A O- (A = alkali metal) are known as tungsten oxide bronzes. These are readily prepared by the insertion of the alkali metal into WO3. The corresponding molybdenum bronzes are more difficult to prepare. High pressures and electrochemical methods are generally employed to synthesize some of them. A simple solid-state reaction between an alkali iodide and M0O3 or Moj j Wj 03 (under dry conditions) has been found to yield such molybdenum oxide bronzes [11]. The following reaction represents a simple means of making these bronzes ... 

Molybdenum and Tungsten Bronzes.—The results of the majority of studies of studies of new bronze phases are summarized in Table 9. Sno.2W03 and Sno.3 WO3 have been prepared and their crystal structures determined. Whether they are bronzes is debatable since they do not involve a host lattice of WO ... 

Molybdenum and Tungsten Bronzes. A single-crystal e.s.r. study of the recently discovered triclinic Na0.33WO3 bronze at 15K has provided the first conclusive evidence for the existence of Wv centres in the tungsten bronzes. These centres are present in a concentration approximately equal to that of the alkali metal. Two different Wv resonances have been observed, suggesting two different Wv point... 

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). 

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