Synthesis of new tungsten bronze phases from peroxo-polytungstate precursors
1997; Elsevier BV; Volume: 96; Issue: 1-2 Linguagem: Inglês
10.1016/s0167-2738(97)00009-x
ISSN1872-7689
Autores Tópico(s)Catalysis and Oxidation Reactions
ResumoAn 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 °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 °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 Å, for Pb0.29WO3) was synthesized similarly but at lower temperature (420 °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.
Referência(s)