STRUCTURAL-ANALYSIS OF MOLYBDENUM BRONZES

Hydrogen molybdenum bronzes, H0.21MoO3 (type I) and H0.91MoO3 (type II ) were characterized by Mo K-edge XAFS spectroscopy. XANES specetra sh owed that type I has an axially symmetric MoO6 unit which is mainly co nncted to each other with vertices sharing and a MoO6 unit in type II are similar to that in MoO2. EXAFS spectra suggested that the MoOx she et in type Iis similar to MoO3 while in type II, a MoOx sheet is simil ar to that in rutile MoO2 in which MoO6 is conneced to form a chain by sharing the edges of opposite sides. The curve fitting analysis of Mo O bonds for type I supported the earlier results obtained from diffrac tion and IR methods; a MoO6 unit has C-4v symmetry. In case of type II , D-4h structure is possible and hydrogen is captured by Mo=O bonds re sulting in the formation of Mo-OH bonds.