Solid State Ionics, Vol.96, No.1-2, 35-40, 1997
Synthesis of New Tungsten Bronze Phases from Peroxo-Polytungstate Precursors
An amorphous salt was precipitated by reacting barium bromide with a solution of peroxo-polytungstic acid. Heating it in a hydrogen stream at temperature near 550 degrees C yielded a hexagonal form of barium tungsten bronze, BaxWO3, in a pure phase with x being in the range 0.19-0.24. At temperature higher than 620 degrees C, this metastable compound was transformed into the tetragonal bronze phase. An unreported lead tungsten bronze in the hexagonal form (a = 7.407, c = 7.565 Angstrom, for Pb(0.29)WO3) was synthesized similarly but at lower temperature (420 degrees C). Their crystal structures were refined by the Rietveld method. The electric properties of the compounds were also investigated between 4.2 K to room temperature.
Keywords:CHEMISTRY