Determination of lead tungstate: Crystalline structure by laser Raman scattering spectra

Two types of structure of lead tungstate scintillating crystals grown from high-temperature melt of the mixed powders of PbO and WO3 have been reporte d in the literatures. One is of space group C-4h(6)-I4(1)/a, i. e. the sche elite structure, and the other D-4h(4)-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 gr oup theory the scheelite structure of the crystals grown from a stoichiomet ric melt was determined in the present paper.