Two types of structure of lead tungstate scintillating crystals grown from high-temperature melt of the mixed powders of PbO and WO3 have been reported in the literatures. One is of space group C64h-I41/a,i.e. the scheelite structure, and the other D4-P4/nnc. It is not easy to determine its exact structure by the X-ray powder diffraction technique. On the bases of measuring its Raman spectra under different geometrical configurations and analyzing its vibration modes in the two different structures by the group theory the scheelite structure of the crystals grown from a stoichiometric melt was determined in the present paper.
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