Raman spectroscopy of bismuth tungstates

The Bi 2 O 3 ‐WO 3 system was examined using Raman spectroscopy. The Raman spectra of bismuth tungstate samples having Bi: W ratios of 2:1, 4:1 and 14:1 were used to identify the bismuth tungstate phases present at these compositions. The bismuth tungstate phases which occur were found to depend on the Bi: W ratio. The 2:1 composition consists of only the Bi 2 WO 6 phase and the 14:1 composition consists almost entirely of the sillenite phase. The 4:1 composition, however, is multi‐phase and consists of Bi 2 WO 6 , the sillenite phase, and another phase referred to as 7Bi 2 O 3 ‐2WO 3 . The Raman spectra were used to determine the coordination of the tungstate species as well as their WO bond lengths in each of these phases.