  Raman spectra of polycrystalline NdFeAsO1-xFx (x=0.0, 0.1, 0.2) compound have
been systematically investigated as functions of temperature and fluorine
concentration. Scanning electron microscopic and Raman microscopic
characterization demonstrates that the polycrystalline samples mainly contain
two phases, i.e. superconductor NdFeAsO1-xFx compound and a MnP-type FeAs
phase, with dissimilar characteristic Raman bands. It was found that fluorine
doping leads to structure disorder in the insulator Nd-O layers and high
temperature coefficient of Fe-As vibrational mode.
