Ternary tungsten oxides with the Mo5O14 structure

Following the discovery of a ternary GeW oxide with the Mo5O14 structure, a large number of ternary MWO systems were surveyed to investigate the frequency of occurrence of this structure type. Samples were prepared by heating tungsten oxides and the appropriate ternary element or a suitable compound of the ternary element in evacuated silica ampoules at 1373°K for 1 week. The compositions investigated were close to M0.02W0.98O2.80. Oxides with the Mo5O14 structure were found in many systems across the whole of the periodic table, from Li to Bi. Some aspects of the formation of these phases and the way in which they could affect the course of reduction of WO3 to W metal are discussed.