Synthesis of new tungsten bronze phases from peroxo-polytungstate precursors

✍ Scribed by Koichi Tatsumi; Mitsuhiro Hibino; Tetsuichi Kudo

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 485 KB
• Volume: 96
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(97)00009-x

✦ Synopsis

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°C yielded a hexagonal form of barium tungsten bronze, Ba,WO,, in a pure phase with n 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 A, for Pb,,,,WO3) 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.