HYDROGEN BRONZES OF NEW OXIDES OF THE WO3-MOO3 SYSTEM WITH HEXAGONAL, PYROCHLORE AND REO3-TYPE STRUCTURES

Hydrogen intercalation via a spillover reaction in new metastable oxides of the MoO3-WO3 System leads to the formation of the corresponding hydrogen bronzes. Phase ranges and variation of both lattice cells and parameters with the intercalated hydrogen content have been established for hexagonal HxWO3, pyrochlore HxWO3, HxMo0.44W0.56O3 with hexagonal-type structure, HxMoO3 and HxMo0.72W0.28O3 with ReO3-type structure. The effect of the host lattice crystal structure of the Mo(VI) content of the parent oxide, on hydrogen intercalation content, on the reversibility of the reaction and on the distortions induced by hydrogen intercalation in the parent oxide framework have also been established and discussed. Electrochemical hydrogen intercalation into these oxides has been studied in relation to electrochromic applications.