We investigate the Raman scattering and electron diffraction (ED) for the n
ominal composition of Bi1.8Pb0.2Sr2-xCuOy samples. It is found that the Sr
vacancies bring about the distortion of Sr-O bond as well as the reduction
of the incommensurate modulation with decreasing Sr content in Bi1.8Pb0.2Sr
2-xCuOy. samples. Our analysis indicates that the characteristics in Raman
scattering spectra can be explained well by the crystal misfit model. (C) 1
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