Synthesis of hydrogen tungsten bronzes HxWO3 by reactive mechanical milling of hexagonal WO3

F. CASTRO; F. TONUS; J.-L. BOBET; G. URRETAVIZCAYA

Buenos Aires, Argentina

Simposio; 15th International Symposium on Metastable, Amorphous and NAnoestructured Materials; 2008

Fernando Audebert (UBA, Conicet), Laura Damonte (UNLP, Conicet), Funprecit

Recently we have reported the formation of hydrogen tungsten bronzes by reactive mechanical alloying monoclinic tungsten (VI) oxide under hydrogen atmosphere. In this work we report the milling of metastable hexagonal WO3 under H2 atmosphere. The characterization of the materials was performed by XRD, DSC, SEM and total hydrogen content determination. Our main result is the formation of different hydrogen tungsten bronzes at distinct milling times. During the first milling times the presence of hexagonal hydrogen tungsten bronze seems to occur. Simultaneously, a fraction of hexagonal oxide experiments a structural transformation to the stable monoclinic structure. After that, the hexagonal bronze disappears and the evolution practically follows the same path than the milling of the monoclinic oxide. Interestingly, the final milling product analyzed immediately after milling shows the presence of cubic hydrogen tungsten bronze with a high hydrogen content, but this structure is rather unstable because after a few days stored in a inert atmosphere it disappears transforming to the stable tetragonal bronze. References: [1]  G. Urretavizcaya, F. Tonus, E. Gaudin, J.-L. Bobet and F. J., J. Solid State Chem. 2785 (2007) 180.