RAMAN-SPECTROSCOPY OF FERRITUNGSTITE - EXPERIMENTAL AND MODEL SPECTRA

Raman spectra of ferritungstite are interpreted on the basis of model calculations. The presence of two broad vibrational bands in the spect ral range 600-1000 cm-1 is explained through the combination of two fa ctors. Mainly, two principle bands in the spectral ranges 600-750 and 850-1000 cm-1 are characteristic of the pyrochlore-type structure atta ined by ferritungstite and correspond to symmetric and asymmetric stre tching of the W-O bonds, respectively. Also, broadening of the Raman l ines results from structural disorder caused by the presence of iron a toms.