Cathodic insertion of ions in tungsten(VI) oxide from aqueous media

Electrochemical insertion of ions in monoclinic tungsten(VI) oxide from aqu eous solutions was investigated at room temperature. The solutions were nit ric acid and solutions of Group I and II nitrates. In all the performed ins ertions, except with lithium nitrate, the obtained intercalates had the com position HxWO3 (0.07 <x <0.84). Within this compositional range two types o f hydrogen intercalated materials were obtained, both with tetragonal symme try. For low degrees of insertion (0.07 <x <0.17) the lattice constants wer e a=b=5.225(2) and c=3.884(4) Angstrom. For high degrees of insertion (0.50 <x <0.84) the lattice constants were a=b=5.358(2) and c=3.749(5) Angstrom. With lithium nitrate as electrolyte solution intercalates with composition LixWO3 were obtained. After exposure to air the lithium intercalated compo unds were tetragonal with lattice constants a=b=5.1996(2) and c=3.8402(1) A ngstrom. The processes where barium nitrate was used as electrolyte were st udied in detail, and the electrochemical processes were determined. The int ercalates were characterized using X-ray powder diffraction, and Rietveld r efinements of the structures of H0.12WO3 and LixWO3 were performed.